Implement SSL service

This implements some missing network APIs including a large chunk of the SSL
service, enough for Mario Maker (with an appropriate mod applied) to connect to
the fan server [Open Course World](https://opencourse.world/).

Connecting to first-party servers is out of scope of this PR and is a
minefield I'd rather not step into.

 ## TLS

TLS is implemented with multiple backends depending on the system's 'native'
TLS library.  Currently there are two backends: Schannel for Windows, and
OpenSSL for Linux.  (In reality Linux is a bit of a free-for-all where there's
no one 'native' library, but OpenSSL is the closest it gets.)  On macOS the
'native' library is SecureTransport but that isn't implemented in this PR.
(Instead, all non-Windows OSes will use OpenSSL unless disabled with
`-DENABLE_OPENSSL=OFF`.)

Why have multiple backends instead of just using a single library, especially
given that Yuzu already embeds mbedtls for cryptographic algorithms?  Well, I
tried implementing this on mbedtls first, but the problem is TLS policies -
mainly trusted certificate policies, and to a lesser extent trusted algorithms,
SSL versions, etc.

...In practice, the chance that someone is going to conduct a man-in-the-middle
attack on a third-party game server is pretty low, but I'm a security nerd so I
like to do the right security things.

My base assumption is that we want to use the host system's TLS policies.  An
alternative would be to more closely emulate the Switch's TLS implementation
(which is based on NSS).  But for one thing, I don't feel like reverse
engineering it.  And I'd argue that for third-party servers such as Open Course
World, it's theoretically preferable to use the system's policies rather than
the Switch's, for two reasons

1. Someday the Switch will stop being updated, and the trusted cert list,
   algorithms, etc. will start to go stale, but users will still want to
   connect to third-party servers, and there's no reason they shouldn't have
   up-to-date security when doing so.  At that point, homebrew users on actual
   hardware may patch the TLS implementation, but for emulators it's simpler to
   just use the host's stack.

2. Also, it's good to respect any custom certificate policies the user may have
   added systemwide.  For example, they may have added custom trusted CAs in
   order to use TLS debugging tools or pass through corporate MitM middleboxes.
   Or they may have removed some CAs that are normally trusted out of paranoia.

Note that this policy wouldn't work as-is for connecting to first-party
servers, because some of them serve certificates based on Nintendo's own CA
rather than a publicly trusted one.  However, this could probably be solved
easily by using appropriate APIs to adding Nintendo's CA as an alternate
trusted cert for Yuzu's connections.  That is not implemented in this PR
because, again, first-party servers are out of scope.

(If anything I'd rather have an option to _block_ connections to Nintendo
servers, but that's not implemented here.)

To use the host's TLS policies, there are three theoretical options:

a) Import the host's trusted certificate list into a cross-platform TLS
   library (presumably mbedtls).

b) Use the native TLS library to verify certificates but use a cross-platform
   TLS library for everything else.

c) Use the native TLS library for everything.

Two problems with option a).  First, importing the trusted certificate list at
minimum requires a bunch of platform-specific code, which mbedtls does not have
built in.  Interestingly, OpenSSL recently gained the ability to import the
Windows certificate trust store... but that leads to the second problem, which
is that a list of trusted certificates is [not expressive
enough](https://bugs.archlinux.org/task/41909) to express a modern certificate
trust policy.  For example, Windows has the concept of [explicitly distrusted
certificates](https://learn.microsoft.com/en-us/previous-versions/windows/it-pro/windows-server-2012-r2-and-2012/dn265983(v=ws.11)),
and macOS requires Certificate Transparency validation for some certificates
with complex rules for when it's required.

Option b) (using native library just to verify certs) is probably feasible, but
it would miss aspects of TLS policy other than trusted certs (like allowed
algorithms), and in any case it might well require writing more code, not less,
compared to using the native library for everything.

So I ended up at option c), using the native library for everything.

What I'd *really* prefer would be to use a third-party library that does option
c) for me.  Rust has a good library for this,
[native-tls](https://docs.rs/native-tls/latest/native_tls/).  I did search, but
I couldn't find a good option in the C or C++ ecosystem, at least not any that
wasn't part of some much larger framework.  I was surprised - isn't this a
pretty common use case?  Well, many applications only need TLS for HTTPS, and they can
use libcurl, which has a TLS abstraction layer internally but doesn't expose
it.  Other applications only support a single TLS library, or use one of the
aforementioned larger frameworks, or are platform-specific to begin with, or of
course are written in a non-C/C++ language, most of which have some canonical
choice for TLS.  But there are also many applications that have a set of TLS
backends just like this; it's just that nobody has gone ahead and abstracted
the pattern into a library, at least not a widespread one.

Amusingly, there is one TLS abstraction layer that Yuzu already bundles: the
one in ffmpeg.  But it is missing some features that would be needed to use it
here (like reusing an existing socket rather than managing the socket itself).
Though, that does mean that the wiki's build instructions for Linux (and macOS
for some reason?) already recommend installing OpenSSL, so no need to update
those.

 ## Other APIs implemented

- Sockets:
    - GetSockOpt(`SO_ERROR`)
    - SetSockOpt(`SO_NOSIGPIPE`) (stub, I have no idea what this does on Switch)
    - `DuplicateSocket` (because the SSL sysmodule calls it internally)
    - More `PollEvents` values

- NSD:
    - `Resolve` and `ResolveEx` (stub, good enough for Open Course World and
      probably most third-party servers, but not first-party)

- SFDNSRES:
    - `GetHostByNameRequest` and `GetHostByNameRequestWithOptions`
    - `ResolverSetOptionRequest` (stub)

 ## Fixes

- Parts of the socket code were previously allocating a `sockaddr` object on
  the stack when calling functions that take a `sockaddr*` (e.g. `accept`).
  This might seem like the right thing to do to avoid illegal aliasing, but in
  fact `sockaddr` is not guaranteed to be large enough to hold any particular
  type of address, only the header.  This worked in practice because in
  practice `sockaddr` is the same size as `sockaddr_in`, but it's not how the
  API is meant to be used.  I changed this to allocate an `sockaddr_in` on the
  stack and `reinterpret_cast` it.  I could try to do something cleverer with
  `aligned_storage`, but casting is the idiomatic way to use these particular
  APIs, so it's really the system's responsibility to avoid any aliasing
  issues.

- I rewrote most of the `GetAddrInfoRequest[WithOptions]` implementation.  The
  old implementation invoked the host's getaddrinfo directly from sfdnsres.cpp,
  and directly passed through the host's socket type, protocol, etc. values
  rather than looking up the corresponding constants on the Switch.  To be
  fair, these constants don't tend to actually vary across systems, but
  still... I added a wrapper for `getaddrinfo` in
  `internal_network/network.cpp` similar to the ones for other socket APIs, and
  changed the `GetAddrInfoRequest` implementation to use it.  While I was at
  it, I rewrote the serialization to use the same approach I used to implement
  `GetHostByNameRequest`, because it reduces the number of size calculations.
  While doing so I removed `AF_INET6` support because the Switch doesn't
  support IPv6; it might be nice to support IPv6 anyway, but that would have to
  apply to all of the socket APIs.

  I also corrected the IPC wrappers for `GetAddrInfoRequest` and
  `GetAddrInfoRequestWithOptions` based on reverse engineering and hardware
  testing.  Every call to `GetAddrInfoRequestWithOptions` returns *four*
  different error codes (IPC status, getaddrinfo error code, netdb error code,
  and errno), and `GetAddrInfoRequest` returns three of those but in a
  different order, and it doesn't really matter but the existing implementation
  was a bit off, as I discovered while testing `GetHostByNameRequest`.

  - The new serialization code is based on two simple helper functions:

    ```cpp
    template <typename T> static void Append(std::vector<u8>& vec, T t);
    void AppendNulTerminated(std::vector<u8>& vec, std::string_view str);
    ```

    I was thinking there must be existing functions somewhere that assist with
    serialization/deserialization of binary data, but all I could find was the
    helper methods in `IOFile` and `HLERequestContext`, not anything that could
    be used with a generic byte buffer.  If I'm not missing something, then
    maybe I should move the above functions to a new header in `common`...
    right now they're just sitting in `sfdnsres.cpp` where they're used.

- Not a fix, but `SocketBase::Recv`/`Send` is changed to use `std::span<u8>`
  rather than `std::vector<u8>&` to avoid needing to copy the data to/from a
  vector when those methods are called from the TLS implementation.

CMakeLists.txt

@@ -63,6 +63,8 @@ option(YUZU_DOWNLOAD_TIME_ZONE_DATA "Always download time zone binaries" OFF)
 
 CMAKE_DEPENDENT_OPTION(YUZU_USE_FASTER_LD "Check if a faster linker is available" ON "NOT WIN32" OFF)
 
+CMAKE_DEPENDENT_OPTION(ENABLE_OPENSSL "Enable OpenSSL backend for ISslConnection" ON "NOT WIN32" OFF)
+
 # On Android, fetch and compile libcxx before doing anything else
 if (ANDROID)
     set(CMAKE_SKIP_INSTALL_RULES ON)
@@ -322,6 +324,10 @@ if (MINGW)
     find_library(MSWSOCK_LIBRARY mswsock REQUIRED)
 endif()
 
+if(ENABLE_OPENSSL)
+    find_package(OpenSSL 3.0.0 REQUIRED)
+endif()
+
 # Please consider this as a stub
 if(ENABLE_QT6 AND Qt6_LOCATION)
     list(APPEND CMAKE_PREFIX_PATH "${Qt6_LOCATION}")

src/common/socket_types.h

@@ -5,15 +5,19 @@
 
 #include "common/common_types.h"
 
+#include <optional>
+
 namespace Network {
 
 /// Address families
 enum class Domain : u8 {
-    INET, ///< Address family for IPv4
+    Unspecified, ///< Can be 0 in getaddrinfo hints
+    INET,        ///< Address family for IPv4
 };
 
 /// Socket types
 enum class Type {
+    Unspecified, ///< Can be 0 in getaddrinfo hints
     STREAM,
     DGRAM,
     RAW,
@@ -22,6 +26,7 @@ enum class Type {
 
 /// Protocol values for sockets
 enum class Protocol : u8 {
+    Unspecified,
     ICMP,
     TCP,
     UDP,
@@ -48,4 +53,13 @@ constexpr u32 FLAG_MSG_PEEK = 0x2;
 constexpr u32 FLAG_MSG_DONTWAIT = 0x80;
 constexpr u32 FLAG_O_NONBLOCK = 0x800;
 
+/// Cross-platform addrinfo structure
+struct AddrInfo {
+    Domain family;
+    Type socket_type;
+    Protocol protocol;
+    SockAddrIn addr;
+    std::optional<std::string> canon_name;
+};
+
 } // namespace Network

src/core/CMakeLists.txt

@@ -723,6 +723,7 @@ add_library(core STATIC
     hle/service/spl/spl_types.h
     hle/service/ssl/ssl.cpp
     hle/service/ssl/ssl.h
+    hle/service/ssl/ssl_backend.h
     hle/service/time/clock_types.h
     hle/service/time/ephemeral_network_system_clock_context_writer.h
     hle/service/time/ephemeral_network_system_clock_core.h
@@ -864,6 +865,19 @@ if (ARCHITECTURE_x86_64 OR ARCHITECTURE_arm64)
     target_link_libraries(core PRIVATE dynarmic::dynarmic)
 endif()
 
+if(ENABLE_OPENSSL)
+    target_sources(core PRIVATE
+        hle/service/ssl/ssl_backend_openssl.cpp)
+    target_link_libraries(core PRIVATE OpenSSL::SSL)
+elseif (WIN32)
+    target_sources(core PRIVATE
+        hle/service/ssl/ssl_backend_schannel.cpp)
+    target_link_libraries(core PRIVATE Secur32)
+else()
+    target_sources(core PRIVATE
+        hle/service/ssl/ssl_backend_none.cpp)
+endif()
+
 if (YUZU_USE_PRECOMPILED_HEADERS)
     target_precompile_headers(core PRIVATE precompiled_headers.h)
 endif()

src/core/hle/service/sockets/bsd.cpp

@@ -20,6 +20,9 @@
 #include "core/internal_network/sockets.h"
 #include "network/network.h"
 
+using Common::Expected;
+using Common::Unexpected;
+
 namespace Service::Sockets {
 
 namespace {
@@ -265,16 +268,19 @@ void BSD::GetSockOpt(HLERequestContext& ctx) {
     const u32 level = rp.Pop<u32>();
     const auto optname = static_cast<OptName>(rp.Pop<u32>());
 
-    LOG_WARNING(Service, "(STUBBED) called. fd={} level={} optname=0x{:x}", fd, level, optname);
-
     std::vector<u8> optval(ctx.GetWriteBufferSize());
 
+    LOG_WARNING(Service, "called. fd={} level={} optname=0x{:x} len=0x{:x}", fd, level, optname,
+                optval.size());
+
+    Errno err = GetSockOptImpl(fd, level, optname, optval);
+
     ctx.WriteBuffer(optval);
 
     IPC::ResponseBuilder rb{ctx, 5};
     rb.Push(ResultSuccess);
-    rb.Push<s32>(-1);
+    rb.Push<s32>(err == Errno::SUCCESS ? 0 : -1);
-    rb.PushEnum(Errno::NOTCONN);
+    rb.PushEnum(err);
     rb.Push<u32>(static_cast<u32>(optval.size()));
 }
 
@@ -436,6 +442,18 @@ void BSD::Close(HLERequestContext& ctx) {
     BuildErrnoResponse(ctx, CloseImpl(fd));
 }
 
+void BSD::DuplicateSocket(HLERequestContext& ctx) {
+    IPC::RequestParser rp{ctx};
+    const s32 fd = rp.Pop<s32>();
+    [[maybe_unused]] const u64 unused = rp.Pop<u64>();
+
+    Common::Expected<s32, Errno> res = DuplicateSocketImpl(fd);
+    IPC::ResponseBuilder rb{ctx, 4};
+    rb.Push(ResultSuccess);
+    rb.Push(res.value_or(0));                         // ret
+    rb.Push(res ? 0 : static_cast<s32>(res.error())); // bsd errno
+}
+
 void BSD::EventFd(HLERequestContext& ctx) {
     IPC::RequestParser rp{ctx};
     const u64 initval = rp.Pop<u64>();
@@ -477,12 +495,12 @@ std::pair<s32, Errno> BSD::SocketImpl(Domain domain, Type type, Protocol protoco
 
     auto room_member = room_network.GetRoomMember().lock();
     if (room_member && room_member->IsConnected()) {
-        descriptor.socket = std::make_unique<Network::ProxySocket>(room_network);
+        descriptor.socket = std::make_shared<Network::ProxySocket>(room_network);
     } else {
-        descriptor.socket = std::make_unique<Network::Socket>();
+        descriptor.socket = std::make_shared<Network::Socket>();
     }
 
-    descriptor.socket->Initialize(Translate(domain), Translate(type), Translate(type, protocol));
+    descriptor.socket->Initialize(Translate(domain), Translate(type), Translate(protocol));
     descriptor.is_connection_based = IsConnectionBased(type);
 
     return {fd, Errno::SUCCESS};
@@ -538,7 +556,7 @@ std::pair<s32, Errno> BSD::PollImpl(std::vector<u8>& write_buffer, std::span<con
     std::transform(fds.begin(), fds.end(), host_pollfds.begin(), [this](PollFD pollfd) {
         Network::PollFD result;
         result.socket = file_descriptors[pollfd.fd]->socket.get();
-        result.events = TranslatePollEventsToHost(pollfd.events);
+        result.events = Translate(pollfd.events);
         result.revents = Network::PollEvents{};
         return result;
     });
@@ -547,7 +565,7 @@ std::pair<s32, Errno> BSD::PollImpl(std::vector<u8>& write_buffer, std::span<con
 
     const size_t num = host_pollfds.size();
     for (size_t i = 0; i < num; ++i) {
-        fds[i].revents = TranslatePollEventsToGuest(host_pollfds[i].revents);
+        fds[i].revents = Translate(host_pollfds[i].revents);
     }
     std::memcpy(write_buffer.data(), fds.data(), length);
 
@@ -617,7 +635,8 @@ Errno BSD::GetPeerNameImpl(s32 fd, std::vector<u8>& write_buffer) {
     }
     const SockAddrIn guest_addrin = Translate(addr_in);
 
-    ASSERT(write_buffer.size() == sizeof(guest_addrin));
+    ASSERT(write_buffer.size() >= sizeof(guest_addrin));
+    write_buffer.resize(sizeof(guest_addrin));
     std::memcpy(write_buffer.data(), &guest_addrin, sizeof(guest_addrin));
     return Translate(bsd_errno);
 }
@@ -633,7 +652,8 @@ Errno BSD::GetSockNameImpl(s32 fd, std::vector<u8>& write_buffer) {
     }
     const SockAddrIn guest_addrin = Translate(addr_in);
 
-    ASSERT(write_buffer.size() == sizeof(guest_addrin));
+    ASSERT(write_buffer.size() >= sizeof(guest_addrin));
+    write_buffer.resize(sizeof(guest_addrin));
     std::memcpy(write_buffer.data(), &guest_addrin, sizeof(guest_addrin));
     return Translate(bsd_errno);
 }
@@ -671,13 +691,47 @@ std::pair<s32, Errno> BSD::FcntlImpl(s32 fd, FcntlCmd cmd, s32 arg) {
     }
 }
 
-Errno BSD::SetSockOptImpl(s32 fd, u32 level, OptName optname, size_t optlen, const void* optval) {
+Errno BSD::GetSockOptImpl(s32 fd, u32 level, OptName optname, std::vector<u8>& optval) {
-    UNIMPLEMENTED_IF(level != 0xffff); // SOL_SOCKET
-
     if (!IsFileDescriptorValid(fd)) {
         return Errno::BADF;
     }
 
+    if (level != static_cast<u32>(SocketLevel::SOCKET)) {
+        UNIMPLEMENTED_MSG("Unknown getsockopt level");
+        return Errno::SUCCESS;
+    }
+
+    Network::SocketBase* const socket = file_descriptors[fd]->socket.get();
+
+    switch (optname) {
+    case OptName::ERROR_: {
+        auto [pending_err, getsockopt_err] = socket->GetPendingError();
+        if (getsockopt_err == Network::Errno::SUCCESS) {
+            Errno translated_pending_err = Translate(pending_err);
+            ASSERT_OR_EXECUTE_MSG(
+                optval.size() == sizeof(Errno), { return Errno::INVAL; },
+                "Incorrect getsockopt option size");
+            optval.resize(sizeof(Errno));
+            memcpy(optval.data(), &translated_pending_err, sizeof(Errno));
+        }
+        return Translate(getsockopt_err);
+    }
+    default:
+        UNIMPLEMENTED_MSG("Unimplemented optname={}", optname);
+        return Errno::SUCCESS;
+    }
+}
+
+Errno BSD::SetSockOptImpl(s32 fd, u32 level, OptName optname, size_t optlen, const void* optval) {
+    if (!IsFileDescriptorValid(fd)) {
+        return Errno::BADF;
+    }
+
+    if (level != static_cast<u32>(SocketLevel::SOCKET)) {
+        UNIMPLEMENTED_MSG("Unknown setsockopt level");
+        return Errno::SUCCESS;
+    }
+
     Network::SocketBase* const socket = file_descriptors[fd]->socket.get();
 
     if (optname == OptName::LINGER) {
@@ -711,6 +765,9 @@ Errno BSD::SetSockOptImpl(s32 fd, u32 level, OptName optname, size_t optlen, con
         return Translate(socket->SetSndTimeo(value));
     case OptName::RCVTIMEO:
         return Translate(socket->SetRcvTimeo(value));
+    case OptName::NOSIGPIPE:
+        LOG_WARNING(Service, "(STUBBED) setting NOSIGPIPE to {}", value);
+        return Errno::SUCCESS;
     default:
         UNIMPLEMENTED_MSG("Unimplemented optname={}", optname);
         return Errno::SUCCESS;
@@ -841,6 +898,28 @@ Errno BSD::CloseImpl(s32 fd) {
     return bsd_errno;
 }
 
+Expected<s32, Errno> BSD::DuplicateSocketImpl(s32 fd) {
+    if (!IsFileDescriptorValid(fd)) {
+        return Unexpected(Errno::BADF);
+    }
+
+    const s32 new_fd = FindFreeFileDescriptorHandle();
+    if (new_fd < 0) {
+        LOG_ERROR(Service, "No more file descriptors available");
+        return Unexpected(Errno::MFILE);
+    }
+
+    file_descriptors[new_fd] = file_descriptors[fd];
+    return new_fd;
+}
+
+std::optional<std::shared_ptr<Network::SocketBase>> BSD::GetSocket(s32 fd) {
+    if (!IsFileDescriptorValid(fd)) {
+        return std::nullopt;
+    }
+    return file_descriptors[fd]->socket;
+}
+
 s32 BSD::FindFreeFileDescriptorHandle() noexcept {
     for (s32 fd = 0; fd < static_cast<s32>(file_descriptors.size()); ++fd) {
         if (!file_descriptors[fd]) {
@@ -911,7 +990,7 @@ BSD::BSD(Core::System& system_, const char* name)
         {24, &BSD::Write, "Write"},
         {25, &BSD::Read, "Read"},
         {26, &BSD::Close, "Close"},
-        {27, nullptr, "DuplicateSocket"},
+        {27, &BSD::DuplicateSocket, "DuplicateSocket"},
         {28, nullptr, "GetResourceStatistics"},
         {29, nullptr, "RecvMMsg"},
         {30, nullptr, "SendMMsg"},

src/core/hle/service/sockets/bsd.h

@@ -8,6 +8,7 @@
 #include <vector>
 
 #include "common/common_types.h"
+#include "common/expected.h"
 #include "common/socket_types.h"
 #include "core/hle/service/service.h"
 #include "core/hle/service/sockets/sockets.h"
@@ -29,12 +30,19 @@ public:
     explicit BSD(Core::System& system_, const char* name);
     ~BSD() override;
 
+    // These methods are called from SSL; the first two are also called from
+    // this class for the corresponding IPC methods.
+    // On the real device, the SSL service makes IPC calls to this service.
+    Common::Expected<s32, Errno> DuplicateSocketImpl(s32 fd);
+    Errno CloseImpl(s32 fd);
+    std::optional<std::shared_ptr<Network::SocketBase>> GetSocket(s32 fd);
+
 private:
     /// Maximum number of file descriptors
     static constexpr size_t MAX_FD = 128;
 
     struct FileDescriptor {
-        std::unique_ptr<Network::SocketBase> socket;
+        std::shared_ptr<Network::SocketBase> socket;
         s32 flags = 0;
         bool is_connection_based = false;
     };
@@ -138,6 +146,7 @@ private:
     void Write(HLERequestContext& ctx);
     void Read(HLERequestContext& ctx);
     void Close(HLERequestContext& ctx);
+    void DuplicateSocket(HLERequestContext& ctx);
     void EventFd(HLERequestContext& ctx);
 
     template <typename Work>
@@ -153,6 +162,7 @@ private:
     Errno GetSockNameImpl(s32 fd, std::vector<u8>& write_buffer);
     Errno ListenImpl(s32 fd, s32 backlog);
     std::pair<s32, Errno> FcntlImpl(s32 fd, FcntlCmd cmd, s32 arg);
+    Errno GetSockOptImpl(s32 fd, u32 level, OptName optname, std::vector<u8>& optval);
     Errno SetSockOptImpl(s32 fd, u32 level, OptName optname, size_t optlen, const void* optval);
     Errno ShutdownImpl(s32 fd, s32 how);
     std::pair<s32, Errno> RecvImpl(s32 fd, u32 flags, std::vector<u8>& message);
@@ -161,7 +171,6 @@ private:
     std::pair<s32, Errno> SendImpl(s32 fd, u32 flags, std::span<const u8> message);
     std::pair<s32, Errno> SendToImpl(s32 fd, u32 flags, std::span<const u8> message,
                                      std::span<const u8> addr);
-    Errno CloseImpl(s32 fd);
 
     s32 FindFreeFileDescriptorHandle() noexcept;
     bool IsFileDescriptorValid(s32 fd) const noexcept;

src/core/hle/service/sockets/nsd.cpp

@@ -1,10 +1,15 @@
 // SPDX-FileCopyrightText: Copyright 2018 yuzu Emulator Project
 // SPDX-License-Identifier: GPL-2.0-or-later
 
+#include "core/hle/service/ipc_helpers.h"
 #include "core/hle/service/sockets/nsd.h"
 
+#include "common/string_util.h"
+
 namespace Service::Sockets {
 
+constexpr Result ResultOverflow{ErrorModule::NSD, 6};
+
 NSD::NSD(Core::System& system_, const char* name) : ServiceFramework{system_, name} {
     // clang-format off
     static const FunctionInfo functions[] = {
@@ -15,8 +20,8 @@ NSD::NSD(Core::System& system_, const char* name) : ServiceFramework{system_, na
         {13, nullptr, "DeleteSettings"},
         {14, nullptr, "ImportSettings"},
         {15, nullptr, "SetChangeEnvironmentIdentifierDisabled"},
-        {20, nullptr, "Resolve"},
+        {20, &NSD::Resolve, "Resolve"},
-        {21, nullptr, "ResolveEx"},
+        {21, &NSD::ResolveEx, "ResolveEx"},
         {30, nullptr, "GetNasServiceSetting"},
         {31, nullptr, "GetNasServiceSettingEx"},
         {40, nullptr, "GetNasRequestFqdn"},
@@ -40,6 +45,55 @@ NSD::NSD(Core::System& system_, const char* name) : ServiceFramework{system_, na
     RegisterHandlers(functions);
 }
 
+static ResultVal<std::string> ResolveImpl(const std::string& fqdn_in) {
+    // The real implementation makes various substitutions.
+    // For now we just return the string as-is, which is good enough when not
+    // connecting to real Nintendo servers.
+    LOG_WARNING(Service, "(STUBBED) called({})", fqdn_in);
+    return fqdn_in;
+}
+
+static Result ResolveCommon(const std::string& fqdn_in, std::array<char, 0x100>& fqdn_out) {
+    const auto res = ResolveImpl(fqdn_in);
+    if (res.Failed()) {
+        return res.Code();
+    }
+    if (res->size() >= fqdn_out.size()) {
+        return ResultOverflow;
+    }
+    std::memcpy(fqdn_out.data(), res->c_str(), res->size() + 1);
+    return ResultSuccess;
+}
+
+void NSD::Resolve(HLERequestContext& ctx) {
+    const std::string fqdn_in = Common::StringFromBuffer(ctx.ReadBuffer(0));
+
+    std::array<char, 0x100> fqdn_out{};
+    Result res = ResolveCommon(fqdn_in, fqdn_out);
+
+    ctx.WriteBuffer(fqdn_out);
+    IPC::ResponseBuilder rb{ctx, 2};
+    rb.Push(res);
+}
+
+void NSD::ResolveEx(HLERequestContext& ctx) {
+    const std::string fqdn_in = Common::StringFromBuffer(ctx.ReadBuffer(0));
+
+    std::array<char, 0x100> fqdn_out;
+    Result res = ResolveCommon(fqdn_in, fqdn_out);
+
+    if (res.IsError()) {
+        IPC::ResponseBuilder rb{ctx, 2};
+        rb.Push(res);
+        return;
+    }
+
+    ctx.WriteBuffer(fqdn_out);
+    IPC::ResponseBuilder rb{ctx, 4};
+    rb.Push(ResultSuccess);
+    rb.Push(ResultSuccess);
+}
+
 NSD::~NSD() = default;
 
 } // namespace Service::Sockets

src/core/hle/service/sockets/nsd.h

@@ -15,6 +15,10 @@ class NSD final : public ServiceFramework<NSD> {
 public:
     explicit NSD(Core::System& system_, const char* name);
     ~NSD() override;
+
+private:
+    void Resolve(HLERequestContext& ctx);
+    void ResolveEx(HLERequestContext& ctx);
 };
 
 } // namespace Service::Sockets

src/core/hle/service/sockets/sfdnsres.cpp

@@ -10,27 +10,18 @@
 #include "core/core.h"
 #include "core/hle/service/ipc_helpers.h"
 #include "core/hle/service/sockets/sfdnsres.h"
+#include "core/hle/service/sockets/sockets.h"
+#include "core/hle/service/sockets/sockets_translate.h"
+#include "core/internal_network/network.h"
 #include "core/memory.h"
 
-#ifdef _WIN32
-#include <ws2tcpip.h>
-#elif YUZU_UNIX
-#include <arpa/inet.h>
-#include <netdb.h>
-#include <netinet/in.h>
-#include <sys/socket.h>
-#ifndef EAI_NODATA
-#define EAI_NODATA EAI_NONAME
-#endif
-#endif
-
 namespace Service::Sockets {
 
 SFDNSRES::SFDNSRES(Core::System& system_) : ServiceFramework{system_, "sfdnsres"} {
     static const FunctionInfo functions[] = {
         {0, nullptr, "SetDnsAddressesPrivateRequest"},
         {1, nullptr, "GetDnsAddressPrivateRequest"},
-        {2, nullptr, "GetHostByNameRequest"},
+        {2, &SFDNSRES::GetHostByNameRequest, "GetHostByNameRequest"},
         {3, nullptr, "GetHostByAddrRequest"},
         {4, nullptr, "GetHostStringErrorRequest"},
         {5, nullptr, "GetGaiStringErrorRequest"},
@@ -38,11 +29,11 @@ SFDNSRES::SFDNSRES(Core::System& system_) : ServiceFramework{system_, "sfdnsres"
         {7, nullptr, "GetNameInfoRequest"},
         {8, nullptr, "RequestCancelHandleRequest"},
         {9, nullptr, "CancelRequest"},
-        {10, nullptr, "GetHostByNameRequestWithOptions"},
+        {10, &SFDNSRES::GetHostByNameRequestWithOptions, "GetHostByNameRequestWithOptions"},
         {11, nullptr, "GetHostByAddrRequestWithOptions"},
         {12, &SFDNSRES::GetAddrInfoRequestWithOptions, "GetAddrInfoRequestWithOptions"},
         {13, nullptr, "GetNameInfoRequestWithOptions"},
-        {14, nullptr, "ResolverSetOptionRequest"},
+        {14, &SFDNSRES::ResolverSetOptionRequest, "ResolverSetOptionRequest"},
         {15, nullptr, "ResolverGetOptionRequest"},
     };
     RegisterHandlers(functions);
@@ -59,188 +50,246 @@ enum class NetDbError : s32 {
     NoData = 4,
 };
 
-static NetDbError AddrInfoErrorToNetDbError(s32 result) {
+static NetDbError GetAddrInfoErrorToNetDbError(GetAddrInfoError result) {
-    // Best effort guess to map errors
+    // These combinations have been verified on console (but are not
+    // exhaustive).
     switch (result) {
-    case 0:
+    case GetAddrInfoError::SUCCESS:
         return NetDbError::Success;
-    case EAI_AGAIN:
+    case GetAddrInfoError::AGAIN:
         return NetDbError::TryAgain;
-    case EAI_NODATA:
+    case GetAddrInfoError::NODATA:
-        return NetDbError::NoData;
+        return NetDbError::HostNotFound;
+    case GetAddrInfoError::SERVICE:
+        return NetDbError::Success;
     default:
         return NetDbError::HostNotFound;
     }
 }
 
-static std::vector<u8> SerializeAddrInfo(const addrinfo* addrinfo, s32 result_code,
+static Errno GetAddrInfoErrorToErrno(GetAddrInfoError result) {
-                                         std::string_view host) {
+    // These combinations have been verified on console (but are not
-    // Adapted from
+    // exhaustive).
-    // https://github.com/switchbrew/libnx/blob/c5a9a909a91657a9818a3b7e18c9b91ff0cbb6e3/nx/source/runtime/resolver.c#L190
+    switch (result) {
-    std::vector<u8> data;
+    case GetAddrInfoError::SUCCESS:
-
+        // Note: Sometimes a successful lookup sets errno to EADDRNOTAVAIL for
-    auto* current = addrinfo;
+        // some reason, but that doesn't seem useful to implement.
-    while (current != nullptr) {
+        return Errno::SUCCESS;
-        struct SerializedResponseHeader {
+    case GetAddrInfoError::AGAIN:
-            u32 magic;
+        return Errno::SUCCESS;
-            s32 flags;
+    case GetAddrInfoError::NODATA:
-            s32 family;
+        return Errno::SUCCESS;
-            s32 socket_type;
+    case GetAddrInfoError::SERVICE:
-            s32 protocol;
+        return Errno::INVAL;
-            u32 address_length;
+    default:
-        };
+        return Errno::SUCCESS;
-        static_assert(sizeof(SerializedResponseHeader) == 0x18,
-                      "Response header size must be 0x18 bytes");
-
-        constexpr auto header_size = sizeof(SerializedResponseHeader);
-        const auto addr_size =
-            current->ai_addr && current->ai_addrlen > 0 ? current->ai_addrlen : 4;
-        const auto canonname_size = current->ai_canonname ? strlen(current->ai_canonname) + 1 : 1;
-
-        const auto last_size = data.size();
-        data.resize(last_size + header_size + addr_size + canonname_size);
-
-        // Header in network byte order
-        SerializedResponseHeader header{};
-
-        constexpr auto HEADER_MAGIC = 0xBEEFCAFE;
-        header.magic = htonl(HEADER_MAGIC);
-        header.family = htonl(current->ai_family);
-        header.flags = htonl(current->ai_flags);
-        header.socket_type = htonl(current->ai_socktype);
-        header.protocol = htonl(current->ai_protocol);
-        header.address_length = current->ai_addr ? htonl((u32)current->ai_addrlen) : 0;
-
-        auto* header_ptr = data.data() + last_size;
-        std::memcpy(header_ptr, &header, header_size);
-
-        if (header.address_length == 0) {
-            std::memset(header_ptr + header_size, 0, 4);
-        } else {
-            switch (current->ai_family) {
-            case AF_INET: {
-                struct SockAddrIn {
-                    s16 sin_family;
-                    u16 sin_port;
-                    u32 sin_addr;
-                    u8 sin_zero[8];
-                };
-
-                SockAddrIn serialized_addr{};
-                const auto addr = *reinterpret_cast<sockaddr_in*>(current->ai_addr);
-                serialized_addr.sin_port = htons(addr.sin_port);
-                serialized_addr.sin_family = htons(addr.sin_family);
-                serialized_addr.sin_addr = htonl(addr.sin_addr.s_addr);
-                std::memcpy(header_ptr + header_size, &serialized_addr, sizeof(SockAddrIn));
-
-                char addr_string_buf[64]{};
-                inet_ntop(AF_INET, &addr.sin_addr, addr_string_buf, std::size(addr_string_buf));
-                LOG_INFO(Service, "Resolved host '{}' to IPv4 address {}", host, addr_string_buf);
-                break;
-            }
-            case AF_INET6: {
-                struct SockAddrIn6 {
-                    s16 sin6_family;
-                    u16 sin6_port;
-                    u32 sin6_flowinfo;
-                    u8 sin6_addr[16];
-                    u32 sin6_scope_id;
-                };
-
-                SockAddrIn6 serialized_addr{};
-                const auto addr = *reinterpret_cast<sockaddr_in6*>(current->ai_addr);
-                serialized_addr.sin6_family = htons(addr.sin6_family);
-                serialized_addr.sin6_port = htons(addr.sin6_port);
-                serialized_addr.sin6_flowinfo = htonl(addr.sin6_flowinfo);
-                serialized_addr.sin6_scope_id = htonl(addr.sin6_scope_id);
-                std::memcpy(serialized_addr.sin6_addr, &addr.sin6_addr,
-                            sizeof(SockAddrIn6::sin6_addr));
-                std::memcpy(header_ptr + header_size, &serialized_addr, sizeof(SockAddrIn6));
-
-                char addr_string_buf[64]{};
-                inet_ntop(AF_INET6, &addr.sin6_addr, addr_string_buf, std::size(addr_string_buf));
-                LOG_INFO(Service, "Resolved host '{}' to IPv6 address {}", host, addr_string_buf);
-                break;
-            }
-            default:
-                std::memcpy(header_ptr + header_size, current->ai_addr, addr_size);
-                break;
-            }
-        }
-        if (current->ai_canonname) {
-            std::memcpy(header_ptr + addr_size, current->ai_canonname, canonname_size);
-        } else {
-            *(header_ptr + header_size + addr_size) = 0;
-        }
-
-        current = current->ai_next;
     }
+}
 
-    // 4-byte sentinel value
+template <typename T>
-    data.push_back(0);
+static void Append(std::vector<u8>& vec, T t) {
-    data.push_back(0);
+    size_t off = vec.size();
-    data.push_back(0);
+    vec.resize(off + sizeof(T));
-    data.push_back(0);
+    std::memcpy(vec.data() + off, &t, sizeof(T));
+}
 
+static void AppendNulTerminated(std::vector<u8>& vec, std::string_view str) {
+    size_t off = vec.size();
+    vec.resize(off + str.size() + 1);
+    std::memcpy(vec.data() + off, str.data(), str.size());
+}
+
+// We implement gethostbyname using the host's getaddrinfo rather than the
+// host's gethostbyname, because it simplifies portability: e.g., getaddrinfo
+// behaves the same on Unix and Windows, unlike gethostbyname where Windows
+// doesn't implement h_errno.
+static std::vector<u8> SerializeAddrInfoAsHostEnt(const std::vector<Network::AddrInfo>& vec,
+                                                  std::string_view host) {
+
+    std::vector<u8> data;
+    // h_name: use the input hostname (append nul-terminated)
+    AppendNulTerminated(data, host);
+    // h_aliases: leave empty
+
+    Append<u32_be>(data, 0); // count of h_aliases
+    // (If the count were nonzero, the aliases would be appended as nul-terminated here.)
+    Append<u16_be>(data, static_cast<u16>(Domain::INET)); // h_addrtype
+    Append<u16_be>(data, sizeof(Network::IPv4Address));   // h_length
+    // h_addr_list:
+    size_t count = vec.size();
+    ASSERT(count <= UINT32_MAX);
+    Append<u32_be>(data, static_cast<uint32_t>(count));
+    for (const Network::AddrInfo& addrinfo : vec) {
+        // On the Switch, this is passed through htonl despite already being
+        // big-endian, so it ends up as little-endian.
+        Append<u32_le>(data, Network::IPv4AddressToInteger(addrinfo.addr.ip));
+
+        LOG_INFO(Service, "Resolved host '{}' to IPv4 address {}", host,
+                 Network::IPv4AddressToString(addrinfo.addr.ip));
+    }
     return data;
 }
 
-static std::pair<u32, s32> GetAddrInfoRequestImpl(HLERequestContext& ctx) {
+static std::pair<u32, GetAddrInfoError> GetHostByNameRequestImpl(HLERequestContext& ctx) {
     struct Parameters {
         u8 use_nsd_resolve;
-        u32 unknown;
+        u32 cancel_handle;
         u64 process_id;
     };
 
     IPC::RequestParser rp{ctx};
     const auto parameters = rp.PopRaw<Parameters>();
 
-    LOG_WARNING(Service,
+    LOG_WARNING(
-                "called with ignored parameters: use_nsd_resolve={}, unknown={}, process_id={}",
+        Service,
-                parameters.use_nsd_resolve, parameters.unknown, parameters.process_id);
+        "called with ignored parameters: use_nsd_resolve={}, cancel_handle={}, process_id={}",
+        parameters.use_nsd_resolve, parameters.cancel_handle, parameters.process_id);
+
+    const auto host_buffer = ctx.ReadBuffer(0);
+    const std::string host = Common::StringFromBuffer(host_buffer);
+    // For now, ignore options, which are in input buffer 1 for GetHostByNameRequestWithOptions.
+
+    auto res = Network::GetAddrInfo(host, /*service*/ std::nullopt);
+    if (!res.has_value()) {
+        return {0, Translate(res.error())};
+    }
+
+    std::vector<u8> data = SerializeAddrInfoAsHostEnt(res.value(), host);
+    u32 data_size = static_cast<u32>(data.size());
+    ctx.WriteBuffer(data, 0);
+
+    return {data_size, GetAddrInfoError::SUCCESS};
+}
+
+void SFDNSRES::GetHostByNameRequest(HLERequestContext& ctx) {
+    auto [data_size, emu_gai_err] = GetHostByNameRequestImpl(ctx);
+
+    IPC::ResponseBuilder rb{ctx, 5};
+    rb.Push(ResultSuccess);
+    rb.Push(static_cast<s32>(GetAddrInfoErrorToNetDbError(emu_gai_err))); // netdb error code
+    rb.Push(static_cast<s32>(GetAddrInfoErrorToErrno(emu_gai_err)));      // errno
+    rb.Push(data_size);                                                   // serialized size
+}
+
+void SFDNSRES::GetHostByNameRequestWithOptions(HLERequestContext& ctx) {
+    auto [data_size, emu_gai_err] = GetHostByNameRequestImpl(ctx);
+
+    IPC::ResponseBuilder rb{ctx, 5};
+    rb.Push(ResultSuccess);
+    rb.Push(data_size);                                                   // serialized size
+    rb.Push(static_cast<s32>(GetAddrInfoErrorToNetDbError(emu_gai_err))); // netdb error code
+    rb.Push(static_cast<s32>(GetAddrInfoErrorToErrno(emu_gai_err)));      // errno
+}
+
+static std::vector<u8> SerializeAddrInfo(const std::vector<Network::AddrInfo>& vec,
+                                         std::string_view host) {
+    // Adapted from
+    // https://github.com/switchbrew/libnx/blob/c5a9a909a91657a9818a3b7e18c9b91ff0cbb6e3/nx/source/runtime/resolver.c#L190
+    std::vector<u8> data;
+
+    for (const Network::AddrInfo& addrinfo : vec) {
+        // serialized addrinfo:
+        Append<u32_be>(data, 0xBEEFCAFE);                                        // magic
+        Append<u32_be>(data, 0);                                                 // ai_flags
+        Append<u32_be>(data, static_cast<u32>(Translate(addrinfo.family)));      // ai_family
+        Append<u32_be>(data, static_cast<u32>(Translate(addrinfo.socket_type))); // ai_socktype
+        Append<u32_be>(data, static_cast<u32>(Translate(addrinfo.protocol)));    // ai_protocol
+        Append<u32_be>(data, sizeof(SockAddrIn));                                // ai_addrlen
+        // ^ *not* sizeof(SerializedSockAddrIn), not that it matters since they're the same size
+
+        // ai_addr:
+        Append<u16_be>(data, static_cast<u16>(Translate(addrinfo.addr.family))); // sin_family
+        // On the Switch, the following fields are passed through htonl despite
+        // already being big-endian, so they end up as little-endian.
+        Append<u16_le>(data, addrinfo.addr.portno);                            // sin_port
+        Append<u32_le>(data, Network::IPv4AddressToInteger(addrinfo.addr.ip)); // sin_addr
+        data.resize(data.size() + 8, 0);                                       // sin_zero
+
+        if (addrinfo.canon_name.has_value()) {
+            AppendNulTerminated(data, *addrinfo.canon_name);
+        } else {
+            data.push_back(0);
+        }
+
+        LOG_INFO(Service, "Resolved host '{}' to IPv4 address {}", host,
+                 Network::IPv4AddressToString(addrinfo.addr.ip));
+    }
+
+    data.resize(data.size() + 4, 0); // 4-byte sentinel value
+
+    return data;
+}
+
+static std::pair<u32, GetAddrInfoError> GetAddrInfoRequestImpl(HLERequestContext& ctx) {
+    struct Parameters {
+        u8 use_nsd_resolve;
+        u32 cancel_handle;
+        u64 process_id;
+    };
+
+    IPC::RequestParser rp{ctx};
+    const auto parameters = rp.PopRaw<Parameters>();
+
+    LOG_WARNING(
+        Service,
+        "called with ignored parameters: use_nsd_resolve={}, cancel_handle={}, process_id={}",
+        parameters.use_nsd_resolve, parameters.cancel_handle, parameters.process_id);
+
+    // TODO: If use_nsd_resolve is true, pass the name through NSD::Resolve
+    // before looking up.
 
     const auto host_buffer = ctx.ReadBuffer(0);
     const std::string host = Common::StringFromBuffer(host_buffer);
 
-    const auto service_buffer = ctx.ReadBuffer(1);
+    std::optional<std::string> service = std::nullopt;
-    const std::string service = Common::StringFromBuffer(service_buffer);
+    if (ctx.CanReadBuffer(1)) {
-
+        std::span<const u8> service_buffer = ctx.ReadBuffer(1);
-    addrinfo* addrinfo;
+        service = Common::StringFromBuffer(service_buffer);
-    // Pass null for hints. Serialized hints are also passed in a buffer, but are ignored for now
-    s32 result_code = getaddrinfo(host.c_str(), service.c_str(), nullptr, &addrinfo);
-
-    u32 data_size = 0;
-    if (result_code == 0 && addrinfo != nullptr) {
-        const std::vector<u8>& data = SerializeAddrInfo(addrinfo, result_code, host);
-        data_size = static_cast<u32>(data.size());
-        freeaddrinfo(addrinfo);
-
-        ctx.WriteBuffer(data, 0);
     }
 
-    return std::make_pair(data_size, result_code);
+    // Serialized hints are also passed in a buffer, but are ignored for now.
+
+    auto res = Network::GetAddrInfo(host, service);
+    if (!res.has_value()) {
+        return {0, Translate(res.error())};
+    }
+
+    std::vector<u8> data = SerializeAddrInfo(res.value(), host);
+    u32 data_size = static_cast<u32>(data.size());
+    ctx.WriteBuffer(data, 0);
+
+    return {data_size, GetAddrInfoError::SUCCESS};
 }
 
 void SFDNSRES::GetAddrInfoRequest(HLERequestContext& ctx) {
-    auto [data_size, result_code] = GetAddrInfoRequestImpl(ctx);
+    auto [data_size, emu_gai_err] = GetAddrInfoRequestImpl(ctx);
 
-    IPC::ResponseBuilder rb{ctx, 4};
+    IPC::ResponseBuilder rb{ctx, 5};
     rb.Push(ResultSuccess);
-    rb.Push(static_cast<s32>(AddrInfoErrorToNetDbError(result_code))); // NetDBErrorCode
+    rb.Push(static_cast<s32>(GetAddrInfoErrorToErrno(emu_gai_err))); // errno
-    rb.Push(result_code);                                              // errno
+    rb.Push(static_cast<s32>(emu_gai_err));                          // getaddrinfo error code
-    rb.Push(data_size);                                                // serialized size
+    rb.Push(data_size);                                              // serialized size
 }
 
 void SFDNSRES::GetAddrInfoRequestWithOptions(HLERequestContext& ctx) {
     // Additional options are ignored
-    auto [data_size, result_code] = GetAddrInfoRequestImpl(ctx);
+    auto [data_size, emu_gai_err] = GetAddrInfoRequestImpl(ctx);
 
-    IPC::ResponseBuilder rb{ctx, 5};
+    IPC::ResponseBuilder rb{ctx, 6};
     rb.Push(ResultSuccess);
-    rb.Push(data_size);                                                // serialized size
+    rb.Push(data_size);                                                   // serialized size
-    rb.Push(result_code);                                              // errno
+    rb.Push(static_cast<s32>(emu_gai_err));                               // getaddrinfo error code
-    rb.Push(static_cast<s32>(AddrInfoErrorToNetDbError(result_code))); // NetDBErrorCode
+    rb.Push(static_cast<s32>(GetAddrInfoErrorToNetDbError(emu_gai_err))); // netdb error code
-    rb.Push(0);
+    rb.Push(static_cast<s32>(GetAddrInfoErrorToErrno(emu_gai_err)));      // errno
+}
+
+void SFDNSRES::ResolverSetOptionRequest(HLERequestContext& ctx) {
+    LOG_WARNING(Service, "(STUBBED) called");
+
+    IPC::ResponseBuilder rb{ctx, 3};
+
+    rb.Push(ResultSuccess);
+    rb.Push<s32>(0); // bsd errno
 }
 
 } // namespace Service::Sockets

src/core/hle/service/sockets/sfdnsres.h

@@ -17,8 +17,11 @@ public:
     ~SFDNSRES() override;
 
 private:
+    void GetHostByNameRequest(HLERequestContext& ctx);
+    void GetHostByNameRequestWithOptions(HLERequestContext& ctx);
     void GetAddrInfoRequest(HLERequestContext& ctx);
     void GetAddrInfoRequestWithOptions(HLERequestContext& ctx);
+    void ResolverSetOptionRequest(HLERequestContext& ctx);
 };
 
 } // namespace Service::Sockets

src/core/hle/service/sockets/sockets.h

@@ -22,13 +22,35 @@ enum class Errno : u32 {
     CONNRESET = 104,
     NOTCONN = 107,
     TIMEDOUT = 110,
+    INPROGRESS = 115,
+};
+
+enum class GetAddrInfoError : s32 {
+    SUCCESS = 0,
+    ADDRFAMILY = 1,
+    AGAIN = 2,
+    BADFLAGS = 3,
+    FAIL = 4,
+    FAMILY = 5,
+    MEMORY = 6,
+    NODATA = 7,
+    NONAME = 8,
+    SERVICE = 9,
+    SOCKTYPE = 10,
+    SYSTEM = 11,
+    BADHINTS = 12,
+    PROTOCOL = 13,
+    OVERFLOW_ = 14, // avoid name collision with Windows macro
+    OTHER = 15,
 };
 
 enum class Domain : u32 {
+    Unspecified = 0,
     INET = 2,
 };
 
 enum class Type : u32 {
+    Unspecified = 0,
     STREAM = 1,
     DGRAM = 2,
     RAW = 3,
@@ -36,12 +58,16 @@ enum class Type : u32 {
 };
 
 enum class Protocol : u32 {
-    UNSPECIFIED = 0,
+    Unspecified = 0,
     ICMP = 1,
     TCP = 6,
     UDP = 17,
 };
 
+enum class SocketLevel : u32 {
+    SOCKET = 0xffff, // i.e. SOL_SOCKET
+};
+
 enum class OptName : u32 {
     REUSEADDR = 0x4,
     KEEPALIVE = 0x8,
@@ -51,6 +77,8 @@ enum class OptName : u32 {
     RCVBUF = 0x1002,
     SNDTIMEO = 0x1005,
     RCVTIMEO = 0x1006,
+    ERROR_ = 0x1007,   // avoid name collision with Windows macro
+    NOSIGPIPE = 0x800, // at least according to libnx
 };
 
 enum class ShutdownHow : s32 {
@@ -80,6 +108,9 @@ enum class PollEvents : u16 {
     Err = 1 << 3,
     Hup = 1 << 4,
     Nval = 1 << 5,
+    RdNorm = 1 << 6,
+    RdBand = 1 << 7,
+    WrBand = 1 << 8,
 };
 
 DECLARE_ENUM_FLAG_OPERATORS(PollEvents);

src/core/hle/service/sockets/sockets_translate.cpp

@@ -29,6 +29,8 @@ Errno Translate(Network::Errno value) {
         return Errno::TIMEDOUT;
     case Network::Errno::CONNRESET:
         return Errno::CONNRESET;
+    case Network::Errno::INPROGRESS:
+        return Errno::INPROGRESS;
     default:
         UNIMPLEMENTED_MSG("Unimplemented errno={}", value);
         return Errno::SUCCESS;
@@ -39,8 +41,50 @@ std::pair<s32, Errno> Translate(std::pair<s32, Network::Errno> value) {
     return {value.first, Translate(value.second)};
 }
 
+GetAddrInfoError Translate(Network::GetAddrInfoError error) {
+    switch (error) {
+    case Network::GetAddrInfoError::SUCCESS:
+        return GetAddrInfoError::SUCCESS;
+    case Network::GetAddrInfoError::ADDRFAMILY:
+        return GetAddrInfoError::ADDRFAMILY;
+    case Network::GetAddrInfoError::AGAIN:
+        return GetAddrInfoError::AGAIN;
+    case Network::GetAddrInfoError::BADFLAGS:
+        return GetAddrInfoError::BADFLAGS;
+    case Network::GetAddrInfoError::FAIL:
+        return GetAddrInfoError::FAIL;
+    case Network::GetAddrInfoError::FAMILY:
+        return GetAddrInfoError::FAMILY;
+    case Network::GetAddrInfoError::MEMORY:
+        return GetAddrInfoError::MEMORY;
+    case Network::GetAddrInfoError::NODATA:
+        return GetAddrInfoError::NODATA;
+    case Network::GetAddrInfoError::NONAME:
+        return GetAddrInfoError::NONAME;
+    case Network::GetAddrInfoError::SERVICE:
+        return GetAddrInfoError::SERVICE;
+    case Network::GetAddrInfoError::SOCKTYPE:
+        return GetAddrInfoError::SOCKTYPE;
+    case Network::GetAddrInfoError::SYSTEM:
+        return GetAddrInfoError::SYSTEM;
+    case Network::GetAddrInfoError::BADHINTS:
+        return GetAddrInfoError::BADHINTS;
+    case Network::GetAddrInfoError::PROTOCOL:
+        return GetAddrInfoError::PROTOCOL;
+    case Network::GetAddrInfoError::OVERFLOW_:
+        return GetAddrInfoError::OVERFLOW_;
+    case Network::GetAddrInfoError::OTHER:
+        return GetAddrInfoError::OTHER;
+    default:
+        UNIMPLEMENTED_MSG("Unimplemented GetAddrInfoError={}", error);
+        return GetAddrInfoError::OTHER;
+    }
+}
+
 Network::Domain Translate(Domain domain) {
     switch (domain) {
+    case Domain::Unspecified:
+        return Network::Domain::Unspecified;
     case Domain::INET:
         return Network::Domain::INET;
     default:
@@ -51,6 +95,8 @@ Network::Domain Translate(Domain domain) {
 
 Domain Translate(Network::Domain domain) {
     switch (domain) {
+    case Network::Domain::Unspecified:
+        return Domain::Unspecified;
     case Network::Domain::INET:
         return Domain::INET;
     default:
@@ -61,39 +107,69 @@ Domain Translate(Network::Domain domain) {
 
 Network::Type Translate(Type type) {
     switch (type) {
+    case Type::Unspecified:
+        return Network::Type::Unspecified;
     case Type::STREAM:
         return Network::Type::STREAM;
     case Type::DGRAM:
         return Network::Type::DGRAM;
+    case Type::RAW:
+        return Network::Type::RAW;
+    case Type::SEQPACKET:
+        return Network::Type::SEQPACKET;
     default:
         UNIMPLEMENTED_MSG("Unimplemented type={}", type);
         return Network::Type{};
     }
 }
 
-Network::Protocol Translate(Type type, Protocol protocol) {
+Type Translate(Network::Type type) {
+    switch (type) {
+    case Network::Type::Unspecified:
+        return Type::Unspecified;
+    case Network::Type::STREAM:
+        return Type::STREAM;
+    case Network::Type::DGRAM:
+        return Type::DGRAM;
+    case Network::Type::RAW:
+        return Type::RAW;
+    case Network::Type::SEQPACKET:
+        return Type::SEQPACKET;
+    default:
+        UNIMPLEMENTED_MSG("Unimplemented type={}", type);
+        return Type{};
+    }
+}
+
+Network::Protocol Translate(Protocol protocol) {
     switch (protocol) {
-    case Protocol::UNSPECIFIED:
+    case Protocol::Unspecified:
-        LOG_WARNING(Service, "Unspecified protocol, assuming protocol from type");
+        return Network::Protocol::Unspecified;
-        switch (type) {
-        case Type::DGRAM:
-            return Network::Protocol::UDP;
-        case Type::STREAM:
-            return Network::Protocol::TCP;
-        default:
-            return Network::Protocol::TCP;
-        }
     case Protocol::TCP:
         return Network::Protocol::TCP;
     case Protocol::UDP:
         return Network::Protocol::UDP;
     default:
         UNIMPLEMENTED_MSG("Unimplemented protocol={}", protocol);
-        return Network::Protocol::TCP;
+        return Network::Protocol::Unspecified;
     }
 }
 
-Network::PollEvents TranslatePollEventsToHost(PollEvents flags) {
+Protocol Translate(Network::Protocol protocol) {
+    switch (protocol) {
+    case Network::Protocol::Unspecified:
+        return Protocol::Unspecified;
+    case Network::Protocol::TCP:
+        return Protocol::TCP;
+    case Network::Protocol::UDP:
+        return Protocol::UDP;
+    default:
+        UNIMPLEMENTED_MSG("Unimplemented protocol={}", protocol);
+        return Protocol::Unspecified;
+    }
+}
+
+Network::PollEvents Translate(PollEvents flags) {
     Network::PollEvents result{};
     const auto translate = [&result, &flags](PollEvents from, Network::PollEvents to) {
         if (True(flags & from)) {
@@ -107,12 +183,15 @@ Network::PollEvents TranslatePollEventsToHost(PollEvents flags) {
     translate(PollEvents::Err, Network::PollEvents::Err);
     translate(PollEvents::Hup, Network::PollEvents::Hup);
     translate(PollEvents::Nval, Network::PollEvents::Nval);
+    translate(PollEvents::RdNorm, Network::PollEvents::RdNorm);
+    translate(PollEvents::RdBand, Network::PollEvents::RdBand);
+    translate(PollEvents::WrBand, Network::PollEvents::WrBand);
 
     UNIMPLEMENTED_IF_MSG((u16)flags != 0, "Unimplemented flags={}", (u16)flags);
     return result;
 }
 
-PollEvents TranslatePollEventsToGuest(Network::PollEvents flags) {
+PollEvents Translate(Network::PollEvents flags) {
     PollEvents result{};
     const auto translate = [&result, &flags](Network::PollEvents from, PollEvents to) {
         if (True(flags & from)) {
@@ -127,13 +206,18 @@ PollEvents TranslatePollEventsToGuest(Network::PollEvents flags) {
     translate(Network::PollEvents::Err, PollEvents::Err);
     translate(Network::PollEvents::Hup, PollEvents::Hup);
     translate(Network::PollEvents::Nval, PollEvents::Nval);
+    translate(Network::PollEvents::RdNorm, PollEvents::RdNorm);
+    translate(Network::PollEvents::RdBand, PollEvents::RdBand);
+    translate(Network::PollEvents::WrBand, PollEvents::WrBand);
 
     UNIMPLEMENTED_IF_MSG((u16)flags != 0, "Unimplemented flags={}", (u16)flags);
     return result;
 }
 
 Network::SockAddrIn Translate(SockAddrIn value) {
-    ASSERT(value.len == 0 || value.len == sizeof(value));
+    // Note: 6 is incorrect, but can be passed by homebrew (because libnx sets
+    // sin_len to 6 when deserializing getaddrinfo results).
+    ASSERT(value.len == 0 || value.len == sizeof(value) || value.len == 6);
 
     return {
         .family = Translate(static_cast<Domain>(value.family)),

src/core/hle/service/sockets/sockets_translate.h

@@ -17,6 +17,9 @@ Errno Translate(Network::Errno value);
 /// Translate abstract return value errno pair to guest return value errno pair
 std::pair<s32, Errno> Translate(std::pair<s32, Network::Errno> value);
 
+/// Translate abstract getaddrinfo error to guest getaddrinfo error
+GetAddrInfoError Translate(Network::GetAddrInfoError value);
+
 /// Translate guest domain to abstract domain
 Network::Domain Translate(Domain domain);
 
@@ -26,14 +29,20 @@ Domain Translate(Network::Domain domain);
 /// Translate guest type to abstract type
 Network::Type Translate(Type type);
 
-/// Translate guest protocol to abstract protocol
+/// Translate abstract type to guest type
-Network::Protocol Translate(Type type, Protocol protocol);
+Type Translate(Network::Type type);
 
-/// Translate abstract poll event flags to guest poll event flags
+/// Translate guest protocol to abstract protocol
-Network::PollEvents TranslatePollEventsToHost(PollEvents flags);
+Network::Protocol Translate(Protocol protocol);
+
+/// Translate abstract protocol to guest protocol
+Protocol Translate(Network::Protocol protocol);
 
 /// Translate guest poll event flags to abstract poll event flags
-PollEvents TranslatePollEventsToGuest(Network::PollEvents flags);
+Network::PollEvents Translate(PollEvents flags);
+
+/// Translate abstract poll event flags to guest poll event flags
+PollEvents Translate(Network::PollEvents flags);
 
 /// Translate guest socket address structure to abstract socket address structure
 Network::SockAddrIn Translate(SockAddrIn value);

src/core/hle/service/ssl/ssl.cpp

@@ -1,10 +1,18 @@
 // SPDX-FileCopyrightText: Copyright 2018 yuzu Emulator Project
 // SPDX-License-Identifier: GPL-2.0-or-later
 
+#include "common/string_util.h"
+
+#include "core/core.h"
 #include "core/hle/service/ipc_helpers.h"
 #include "core/hle/service/server_manager.h"
 #include "core/hle/service/service.h"
+#include "core/hle/service/sm/sm.h"
+#include "core/hle/service/sockets/bsd.h"
 #include "core/hle/service/ssl/ssl.h"
+#include "core/hle/service/ssl/ssl_backend.h"
+#include "core/internal_network/network.h"
+#include "core/internal_network/sockets.h"
 
 namespace Service::SSL {
 
@@ -20,6 +28,18 @@ enum class ContextOption : u32 {
     CrlImportDateCheckEnable = 1,
 };
 
+// This is nn::ssl::Connection::IoMode
+enum class IoMode : u32 {
+    Blocking = 1,
+    NonBlocking = 2,
+};
+
+// This is nn::ssl::sf::OptionType
+enum class OptionType : u32 {
+    DoNotCloseSocket = 0,
+    GetServerCertChain = 1,
+};
+
 // This is nn::ssl::sf::SslVersion
 struct SslVersion {
     union {
@@ -34,35 +54,42 @@ struct SslVersion {
     };
 };
 
+struct SslContextSharedData {
+    u32 connection_count = 0;
+};
+
 class ISslConnection final : public ServiceFramework<ISslConnection> {
 public:
-    explicit ISslConnection(Core::System& system_, SslVersion version)
+    explicit ISslConnection(Core::System& system_, SslVersion version,
-        : ServiceFramework{system_, "ISslConnection"}, ssl_version{version} {
+                            std::shared_ptr<SslContextSharedData>& shared_data,
+                            std::unique_ptr<SSLConnectionBackend>&& backend)
+        : ServiceFramework{system_, "ISslConnection"}, ssl_version{version},
+          shared_data_{shared_data}, backend_{std::move(backend)} {
         // clang-format off
         static const FunctionInfo functions[] = {
-            {0, nullptr, "SetSocketDescriptor"},
+            {0, &ISslConnection::SetSocketDescriptor, "SetSocketDescriptor"},
-            {1, nullptr, "SetHostName"},
+            {1, &ISslConnection::SetHostName, "SetHostName"},
-            {2, nullptr, "SetVerifyOption"},
+            {2, &ISslConnection::SetVerifyOption, "SetVerifyOption"},
-            {3, nullptr, "SetIoMode"},
+            {3, &ISslConnection::SetIoMode, "SetIoMode"},
             {4, nullptr, "GetSocketDescriptor"},
             {5, nullptr, "GetHostName"},
             {6, nullptr, "GetVerifyOption"},
             {7, nullptr, "GetIoMode"},
-            {8, nullptr, "DoHandshake"},
+            {8, &ISslConnection::DoHandshake, "DoHandshake"},
-            {9, nullptr, "DoHandshakeGetServerCert"},
+            {9, &ISslConnection::DoHandshakeGetServerCert, "DoHandshakeGetServerCert"},
-            {10, nullptr, "Read"},
+            {10, &ISslConnection::Read, "Read"},
-            {11, nullptr, "Write"},
+            {11, &ISslConnection::Write, "Write"},
-            {12, nullptr, "Pending"},
+            {12, &ISslConnection::Pending, "Pending"},
             {13, nullptr, "Peek"},
             {14, nullptr, "Poll"},
             {15, nullptr, "GetVerifyCertError"},
             {16, nullptr, "GetNeededServerCertBufferSize"},
-            {17, nullptr, "SetSessionCacheMode"},
+            {17, &ISslConnection::SetSessionCacheMode, "SetSessionCacheMode"},
             {18, nullptr, "GetSessionCacheMode"},
             {19, nullptr, "FlushSessionCache"},
             {20, nullptr, "SetRenegotiationMode"},
             {21, nullptr, "GetRenegotiationMode"},
-            {22, nullptr, "SetOption"},
+            {22, &ISslConnection::SetOption, "SetOption"},
             {23, nullptr, "GetOption"},
             {24, nullptr, "GetVerifyCertErrors"},
             {25, nullptr, "GetCipherInfo"},
@@ -80,21 +107,295 @@ public:
         // clang-format on
 
         RegisterHandlers(functions);
+
+        shared_data->connection_count++;
+    }
+
+    ~ISslConnection() {
+        shared_data_->connection_count--;
+        if (fd_to_close_.has_value()) {
+            s32 fd = *fd_to_close_;
+            if (!do_not_close_socket_) {
+                LOG_ERROR(Service_SSL,
+                          "do_not_close_socket was changed after setting socket; is this right?");
+            } else {
+                auto bsd = system.ServiceManager().GetService<Service::Sockets::BSD>("bsd:u");
+                if (bsd) {
+                    auto err = bsd->CloseImpl(fd);
+                    if (err != Service::Sockets::Errno::SUCCESS) {
+                        LOG_ERROR(Service_SSL, "failed to close duplicated socket: {}", err);
+                    }
+                }
+            }
+        }
     }
 
 private:
     SslVersion ssl_version;
+    std::shared_ptr<SslContextSharedData> shared_data_;
+    std::unique_ptr<SSLConnectionBackend> backend_;
+    std::optional<int> fd_to_close_;
+    bool do_not_close_socket_ = false;
+    bool get_server_cert_chain_ = false;
+    std::shared_ptr<Network::SocketBase> socket_;
+    bool did_set_host_name_ = false;
+    bool did_handshake_ = false;
+
+    ResultVal<s32> SetSocketDescriptorImpl(s32 fd) {
+        LOG_DEBUG(Service_SSL, "called, fd={}", fd);
+        ASSERT(!did_handshake_);
+        auto bsd = system.ServiceManager().GetService<Service::Sockets::BSD>("bsd:u");
+        ASSERT_OR_EXECUTE(bsd, { return ResultInternalError; });
+        s32 ret_fd;
+        // Based on https://switchbrew.org/wiki/SSL_services#SetSocketDescriptor
+        if (do_not_close_socket_) {
+            auto res = bsd->DuplicateSocketImpl(fd);
+            if (!res.has_value()) {
+                LOG_ERROR(Service_SSL, "failed to duplicate socket");
+                return ResultInvalidSocket;
+            }
+            fd = *res;
+            fd_to_close_ = fd;
+            ret_fd = fd;
+        } else {
+            ret_fd = -1;
+        }
+        std::optional<std::shared_ptr<Network::SocketBase>> sock = bsd->GetSocket(fd);
+        if (!sock.has_value()) {
+            LOG_ERROR(Service_SSL, "invalid socket fd {}", fd);
+            return ResultInvalidSocket;
+        }
+        socket_ = std::move(*sock);
+        backend_->SetSocket(socket_);
+        return ret_fd;
+    }
+
+    Result SetHostNameImpl(const std::string& hostname) {
+        LOG_DEBUG(Service_SSL, "SetHostNameImpl({})", hostname);
+        ASSERT(!did_handshake_);
+        Result res = backend_->SetHostName(hostname);
+        if (res == ResultSuccess) {
+            did_set_host_name_ = true;
+        }
+        return res;
+    }
+
+    Result SetVerifyOptionImpl(u32 option) {
+        ASSERT(!did_handshake_);
+        LOG_WARNING(Service_SSL, "(STUBBED) called. option={}", option);
+        return ResultSuccess;
+    }
+
+    Result SetIOModeImpl(u32 _mode) {
+        auto mode = static_cast<IoMode>(_mode);
+        ASSERT(mode == IoMode::Blocking || mode == IoMode::NonBlocking);
+        ASSERT_OR_EXECUTE(socket_, { return ResultNoSocket; });
+
+        bool non_block = mode == IoMode::NonBlocking;
+        Network::Errno e = socket_->SetNonBlock(non_block);
+        if (e != Network::Errno::SUCCESS) {
+            LOG_ERROR(Service_SSL, "Failed to set native socket non-block flag to {}", non_block);
+        }
+        return ResultSuccess;
+    }
+
+    Result SetSessionCacheModeImpl(u32 mode) {
+        ASSERT(!did_handshake_);
+        LOG_WARNING(Service_SSL, "(STUBBED) called. value={}", mode);
+        return ResultSuccess;
+    }
+
+    Result DoHandshakeImpl() {
+        ASSERT_OR_EXECUTE(!did_handshake_ && socket_, { return ResultNoSocket; });
+        ASSERT_OR_EXECUTE_MSG(
+            did_set_host_name_, { return ResultInternalError; },
+            "Expected SetHostName before DoHandshake");
+        Result res = backend_->DoHandshake();
+        did_handshake_ = res.IsSuccess();
+        return res;
+    }
+
+    std::vector<u8> SerializeServerCerts(const std::vector<std::vector<u8>>& certs) {
+        struct Header {
+            u64 magic;
+            u32 count;
+            u32 pad;
+        };
+        struct EntryHeader {
+            u32 size;
+            u32 offset;
+        };
+        if (!get_server_cert_chain_) {
+            // Just return the first one, unencoded.
+            ASSERT_OR_EXECUTE_MSG(
+                !certs.empty(), { return {}; }, "Should be at least one server cert");
+            return certs[0];
+        }
+        std::vector<u8> ret;
+        Header header{0x4E4D684374726543, static_cast<u32>(certs.size()), 0};
+        ret.insert(ret.end(), reinterpret_cast<u8*>(&header), reinterpret_cast<u8*>(&header + 1));
+        size_t data_offset = sizeof(Header) + certs.size() * sizeof(EntryHeader);
+        for (auto& cert : certs) {
+            EntryHeader entry_header{static_cast<u32>(cert.size()), static_cast<u32>(data_offset)};
+            data_offset += cert.size();
+            ret.insert(ret.end(), reinterpret_cast<u8*>(&entry_header),
+                       reinterpret_cast<u8*>(&entry_header + 1));
+        }
+        for (auto& cert : certs) {
+            ret.insert(ret.end(), cert.begin(), cert.end());
+        }
+        return ret;
+    }
+
+    ResultVal<std::vector<u8>> ReadImpl(size_t size) {
+        ASSERT_OR_EXECUTE(did_handshake_, { return ResultInternalError; });
+        std::vector<u8> res(size);
+        ResultVal<size_t> actual = backend_->Read(res);
+        if (actual.Failed()) {
+            return actual.Code();
+        }
+        res.resize(*actual);
+        return res;
+    }
+
+    ResultVal<size_t> WriteImpl(std::span<const u8> data) {
+        ASSERT_OR_EXECUTE(did_handshake_, { return ResultInternalError; });
+        return backend_->Write(data);
+    }
+
+    ResultVal<s32> PendingImpl() {
+        LOG_WARNING(Service_SSL, "(STUBBED) called.");
+        return 0;
+    }
+
+    void SetSocketDescriptor(HLERequestContext& ctx) {
+        IPC::RequestParser rp{ctx};
+        const s32 fd = rp.Pop<s32>();
+        const ResultVal<s32> res = SetSocketDescriptorImpl(fd);
+        IPC::ResponseBuilder rb{ctx, 3};
+        rb.Push(res.Code());
+        rb.Push<s32>(res.ValueOr(-1));
+    }
+
+    void SetHostName(HLERequestContext& ctx) {
+        const std::string hostname = Common::StringFromBuffer(ctx.ReadBuffer());
+        const Result res = SetHostNameImpl(hostname);
+        IPC::ResponseBuilder rb{ctx, 2};
+        rb.Push(res);
+    }
+
+    void SetVerifyOption(HLERequestContext& ctx) {
+        IPC::RequestParser rp{ctx};
+        const u32 option = rp.Pop<u32>();
+        const Result res = SetVerifyOptionImpl(option);
+        IPC::ResponseBuilder rb{ctx, 2};
+        rb.Push(res);
+    }
+
+    void SetIoMode(HLERequestContext& ctx) {
+        IPC::RequestParser rp{ctx};
+        const u32 mode = rp.Pop<u32>();
+        const Result res = SetIOModeImpl(mode);
+        IPC::ResponseBuilder rb{ctx, 2};
+        rb.Push(res);
+    }
+
+    void DoHandshake(HLERequestContext& ctx) {
+        const Result res = DoHandshakeImpl();
+        IPC::ResponseBuilder rb{ctx, 2};
+        rb.Push(res);
+    }
+
+    void DoHandshakeGetServerCert(HLERequestContext& ctx) {
+        Result res = DoHandshakeImpl();
+        u32 certs_count = 0;
+        u32 certs_size = 0;
+        if (res == ResultSuccess) {
+            auto certs = backend_->GetServerCerts();
+            if (certs.Succeeded()) {
+                std::vector<u8> certs_buf = SerializeServerCerts(*certs);
+                ctx.WriteBuffer(certs_buf);
+                certs_count = static_cast<u32>(certs->size());
+                certs_size = static_cast<u32>(certs_buf.size());
+            }
+        }
+        IPC::ResponseBuilder rb{ctx, 4};
+        rb.Push(res);
+        rb.Push(certs_size);
+        rb.Push(certs_count);
+    }
+
+    void Read(HLERequestContext& ctx) {
+        const ResultVal<std::vector<u8>> res = ReadImpl(ctx.GetWriteBufferSize());
+        IPC::ResponseBuilder rb{ctx, 3};
+        rb.Push(res.Code());
+        if (res.Succeeded()) {
+            rb.Push(static_cast<u32>(res->size()));
+            ctx.WriteBuffer(*res);
+        } else {
+            rb.Push(static_cast<u32>(0));
+        }
+    }
+
+    void Write(HLERequestContext& ctx) {
+        const ResultVal<size_t> res = WriteImpl(ctx.ReadBuffer());
+        IPC::ResponseBuilder rb{ctx, 3};
+        rb.Push(res.Code());
+        rb.Push(static_cast<u32>(res.ValueOr(0)));
+    }
+
+    void Pending(HLERequestContext& ctx) {
+        const ResultVal<s32> res = PendingImpl();
+        IPC::ResponseBuilder rb{ctx, 3};
+        rb.Push(res.Code());
+        rb.Push<s32>(res.ValueOr(0));
+    }
+
+    void SetSessionCacheMode(HLERequestContext& ctx) {
+        IPC::RequestParser rp{ctx};
+        const u32 mode = rp.Pop<u32>();
+        const Result res = SetSessionCacheModeImpl(mode);
+        IPC::ResponseBuilder rb{ctx, 2};
+        rb.Push(res);
+    }
+
+    void SetOption(HLERequestContext& ctx) {
+        struct Parameters {
+            OptionType option;
+            s32 value;
+        };
+        static_assert(sizeof(Parameters) == 0x8, "Parameters is an invalid size");
+
+        IPC::RequestParser rp{ctx};
+        const auto parameters = rp.PopRaw<Parameters>();
+
+        switch (parameters.option) {
+        case OptionType::DoNotCloseSocket:
+            do_not_close_socket_ = static_cast<bool>(parameters.value);
+            break;
+        case OptionType::GetServerCertChain:
+            get_server_cert_chain_ = static_cast<bool>(parameters.value);
+            break;
+        default:
+            LOG_WARNING(Service_SSL, "unrecognized option={}, value={}", parameters.option,
+                        parameters.value);
+        }
+
+        IPC::ResponseBuilder rb{ctx, 2};
+        rb.Push(ResultSuccess);
+    }
 };
 
 class ISslContext final : public ServiceFramework<ISslContext> {
 public:
     explicit ISslContext(Core::System& system_, SslVersion version)
-        : ServiceFramework{system_, "ISslContext"}, ssl_version{version} {
+        : ServiceFramework{system_, "ISslContext"}, ssl_version{version},
+          shared_data_{std::make_shared<SslContextSharedData>()} {
         static const FunctionInfo functions[] = {
             {0, &ISslContext::SetOption, "SetOption"},
             {1, nullptr, "GetOption"},
             {2, &ISslContext::CreateConnection, "CreateConnection"},
-            {3, nullptr, "GetConnectionCount"},
+            {3, &ISslContext::GetConnectionCount, "GetConnectionCount"},
             {4, &ISslContext::ImportServerPki, "ImportServerPki"},
             {5, &ISslContext::ImportClientPki, "ImportClientPki"},
             {6, nullptr, "RemoveServerPki"},
@@ -111,6 +412,7 @@ public:
 
 private:
     SslVersion ssl_version;
+    std::shared_ptr<SslContextSharedData> shared_data_;
 
     void SetOption(HLERequestContext& ctx) {
         struct Parameters {
@@ -130,11 +432,24 @@ private:
     }
 
     void CreateConnection(HLERequestContext& ctx) {
-        LOG_WARNING(Service_SSL, "(STUBBED) called");
+        LOG_WARNING(Service_SSL, "called");
+
+        auto backend_res = CreateSSLConnectionBackend();
 
         IPC::ResponseBuilder rb{ctx, 2, 0, 1};
+        rb.Push(backend_res.Code());
+        if (backend_res.Succeeded()) {
+            rb.PushIpcInterface<ISslConnection>(system, ssl_version, shared_data_,
+                                                std::move(*backend_res));
+        }
+    }
+
+    void GetConnectionCount(HLERequestContext& ctx) {
+        LOG_WARNING(Service_SSL, "connection_count={}", shared_data_->connection_count);
+
+        IPC::ResponseBuilder rb{ctx, 3};
         rb.Push(ResultSuccess);
-        rb.PushIpcInterface<ISslConnection>(system, ssl_version);
+        rb.Push(shared_data_->connection_count);
     }
 
     void ImportServerPki(HLERequestContext& ctx) {

src/core/hle/service/ssl/ssl_backend.h

@@ -0,0 +1,44 @@
+// SPDX-FileCopyrightText: Copyright 2023 yuzu Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#pragma once
+
+#include "core/hle/result.h"
+
+#include "common/common_types.h"
+
+#include <memory>
+#include <span>
+#include <string>
+#include <vector>
+
+namespace Network {
+class SocketBase;
+}
+
+namespace Service::SSL {
+
+constexpr Result ResultNoSocket{ErrorModule::SSLSrv, 103};
+constexpr Result ResultInvalidSocket{ErrorModule::SSLSrv, 106};
+constexpr Result ResultTimeout{ErrorModule::SSLSrv, 205};
+constexpr Result ResultInternalError{ErrorModule::SSLSrv, 999}; // made up
+
+constexpr Result ResultWouldBlock{ErrorModule::SSLSrv, 204};
+// ^ ResultWouldBlock is returned from Read and Write, and oddly, DoHandshake,
+// with no way in the latter case to distinguish whether the client should poll
+// for read or write.  The one official client I've seen handles this by always
+// polling for read (with a timeout).
+
+class SSLConnectionBackend {
+public:
+    virtual void SetSocket(std::shared_ptr<Network::SocketBase> socket) = 0;
+    virtual Result SetHostName(const std::string& hostname) = 0;
+    virtual Result DoHandshake() = 0;
+    virtual ResultVal<size_t> Read(std::span<u8> data) = 0;
+    virtual ResultVal<size_t> Write(std::span<const u8> data) = 0;
+    virtual ResultVal<std::vector<std::vector<u8>>> GetServerCerts() = 0;
+};
+
+ResultVal<std::unique_ptr<SSLConnectionBackend>> CreateSSLConnectionBackend();
+
+} // namespace Service::SSL

src/core/hle/service/ssl/ssl_backend_none.cpp

@@ -0,0 +1,15 @@
+// SPDX-FileCopyrightText: Copyright 2023 yuzu Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include "core/hle/service/ssl/ssl_backend.h"
+
+#include "common/logging/log.h"
+
+namespace Service::SSL {
+
+ResultVal<std::unique_ptr<SSLConnectionBackend>> CreateSSLConnectionBackend() {
+    LOG_ERROR(Service_SSL, "No SSL backend on this platform");
+    return ResultInternalError;
+}
+
+} // namespace Service::SSL

src/core/hle/service/ssl/ssl_backend_openssl.cpp

@@ -0,0 +1,342 @@
+// SPDX-FileCopyrightText: Copyright 2023 yuzu Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include "core/hle/service/ssl/ssl_backend.h"
+#include "core/internal_network/network.h"
+#include "core/internal_network/sockets.h"
+
+#include "common/fs/file.h"
+#include "common/hex_util.h"
+#include "common/string_util.h"
+
+#include <mutex>
+
+#include <openssl/bio.h>
+#include <openssl/err.h>
+#include <openssl/ssl.h>
+#include <openssl/x509.h>
+
+using namespace Common::FS;
+
+namespace Service::SSL {
+
+// Import OpenSSL's `SSL` type into the namespace.  This is needed because the
+// namespace is also named `SSL`.
+using ::SSL;
+
+namespace {
+
+std::once_flag one_time_init_flag;
+bool one_time_init_success = false;
+
+SSL_CTX* ssl_ctx;
+IOFile key_log_file; // only open if SSLKEYLOGFILE set in environment
+BIO_METHOD* bio_meth;
+
+Result CheckOpenSSLErrors();
+void OneTimeInit();
+void OneTimeInitLogFile();
+bool OneTimeInitBIO();
+
+} // namespace
+
+class SSLConnectionBackendOpenSSL final : public SSLConnectionBackend {
+public:
+    Result Init() {
+        std::call_once(one_time_init_flag, OneTimeInit);
+
+        if (!one_time_init_success) {
+            LOG_ERROR(Service_SSL,
+                      "Can't create SSL connection because OpenSSL one-time initialization failed");
+            return ResultInternalError;
+        }
+
+        ssl_ = SSL_new(ssl_ctx);
+        if (!ssl_) {
+            LOG_ERROR(Service_SSL, "SSL_new failed");
+            return CheckOpenSSLErrors();
+        }
+
+        SSL_set_connect_state(ssl_);
+
+        bio_ = BIO_new(bio_meth);
+        if (!bio_) {
+            LOG_ERROR(Service_SSL, "BIO_new failed");
+            return CheckOpenSSLErrors();
+        }
+
+        BIO_set_data(bio_, this);
+        BIO_set_init(bio_, 1);
+        SSL_set_bio(ssl_, bio_, bio_);
+
+        return ResultSuccess;
+    }
+
+    void SetSocket(std::shared_ptr<Network::SocketBase> socket) override {
+        socket_ = socket;
+    }
+
+    Result SetHostName(const std::string& hostname) override {
+        if (!SSL_set1_host(ssl_, hostname.c_str())) { // hostname for verification
+            LOG_ERROR(Service_SSL, "SSL_set1_host({}) failed", hostname);
+            return CheckOpenSSLErrors();
+        }
+        if (!SSL_set_tlsext_host_name(ssl_, hostname.c_str())) { // hostname for SNI
+            LOG_ERROR(Service_SSL, "SSL_set_tlsext_host_name({}) failed", hostname);
+            return CheckOpenSSLErrors();
+        }
+        return ResultSuccess;
+    }
+
+    Result DoHandshake() override {
+        SSL_set_verify_result(ssl_, X509_V_OK);
+        int ret = SSL_do_handshake(ssl_);
+        long verify_result = SSL_get_verify_result(ssl_);
+        if (verify_result != X509_V_OK) {
+            LOG_ERROR(Service_SSL, "SSL cert verification failed because: {}",
+                      X509_verify_cert_error_string(verify_result));
+            return CheckOpenSSLErrors();
+        }
+        if (ret <= 0) {
+            int ssl_err = SSL_get_error(ssl_, ret);
+            if (ssl_err == SSL_ERROR_ZERO_RETURN ||
+                (ssl_err == SSL_ERROR_SYSCALL && got_read_eof_)) {
+                LOG_ERROR(Service_SSL, "SSL handshake failed because server hung up");
+                return ResultInternalError;
+            }
+        }
+        return HandleReturn("SSL_do_handshake", 0, ret).Code();
+    }
+
+    ResultVal<size_t> Read(std::span<u8> data) override {
+        size_t actual;
+        int ret = SSL_read_ex(ssl_, data.data(), data.size(), &actual);
+        return HandleReturn("SSL_read_ex", actual, ret);
+    }
+
+    ResultVal<size_t> Write(std::span<const u8> data) override {
+        size_t actual;
+        int ret = SSL_write_ex(ssl_, data.data(), data.size(), &actual);
+        return HandleReturn("SSL_write_ex", actual, ret);
+    }
+
+    ResultVal<size_t> HandleReturn(const char* what, size_t actual, int ret) {
+        int ssl_err = SSL_get_error(ssl_, ret);
+        CheckOpenSSLErrors();
+        switch (ssl_err) {
+        case SSL_ERROR_NONE:
+            return actual;
+        case SSL_ERROR_ZERO_RETURN:
+            LOG_DEBUG(Service_SSL, "{} => SSL_ERROR_ZERO_RETURN", what);
+            // DoHandshake special-cases this, but for Read and Write:
+            return size_t(0);
+        case SSL_ERROR_WANT_READ:
+            LOG_DEBUG(Service_SSL, "{} => SSL_ERROR_WANT_READ", what);
+            return ResultWouldBlock;
+        case SSL_ERROR_WANT_WRITE:
+            LOG_DEBUG(Service_SSL, "{} => SSL_ERROR_WANT_WRITE", what);
+            return ResultWouldBlock;
+        default:
+            if (ssl_err == SSL_ERROR_SYSCALL && got_read_eof_) {
+                LOG_DEBUG(Service_SSL, "{} => SSL_ERROR_SYSCALL because server hung up", what);
+                return size_t(0);
+            }
+            LOG_ERROR(Service_SSL, "{} => other SSL_get_error return value {}", what, ssl_err);
+            return ResultInternalError;
+        }
+    }
+
+    ResultVal<std::vector<std::vector<u8>>> GetServerCerts() override {
+        STACK_OF(X509)* chain = SSL_get_peer_cert_chain(ssl_);
+        if (!chain) {
+            LOG_ERROR(Service_SSL, "SSL_get_peer_cert_chain returned nullptr");
+            return ResultInternalError;
+        }
+        std::vector<std::vector<u8>> ret;
+        int count = sk_X509_num(chain);
+        ASSERT(count >= 0);
+        for (int i = 0; i < count; i++) {
+            X509* x509 = sk_X509_value(chain, i);
+            ASSERT_OR_EXECUTE(x509 != nullptr, { continue; });
+            unsigned char* buf = nullptr;
+            int len = i2d_X509(x509, &buf);
+            ASSERT_OR_EXECUTE(len >= 0 && buf, { continue; });
+            ret.emplace_back(buf, buf + len);
+            OPENSSL_free(buf);
+        }
+        return ret;
+    }
+
+    ~SSLConnectionBackendOpenSSL() {
+        // these are null-tolerant:
+        SSL_free(ssl_);
+        BIO_free(bio_);
+    }
+
+    static void KeyLogCallback(const SSL* ssl, const char* line) {
+        std::string str(line);
+        str.push_back('\n');
+        // Do this in a single WriteString for atomicity if multiple instances
+        // are running on different threads (though that can't currently
+        // happen).
+        if (key_log_file.WriteString(str) != str.size() || !key_log_file.Flush()) {
+            LOG_CRITICAL(Service_SSL, "Failed to write to SSLKEYLOGFILE");
+        }
+        LOG_DEBUG(Service_SSL, "Wrote to SSLKEYLOGFILE: {}", line);
+    }
+
+    static int WriteCallback(BIO* bio, const char* buf, size_t len, size_t* actual_p) {
+        auto self = static_cast<SSLConnectionBackendOpenSSL*>(BIO_get_data(bio));
+        ASSERT_OR_EXECUTE_MSG(
+            self->socket_, { return 0; }, "OpenSSL asked to send but we have no socket");
+        BIO_clear_retry_flags(bio);
+        auto [actual, err] = self->socket_->Send({reinterpret_cast<const u8*>(buf), len}, 0);
+        switch (err) {
+        case Network::Errno::SUCCESS:
+            *actual_p = actual;
+            return 1;
+        case Network::Errno::AGAIN:
+            BIO_set_flags(bio, BIO_FLAGS_WRITE | BIO_FLAGS_SHOULD_RETRY);
+            return 0;
+        default:
+            LOG_ERROR(Service_SSL, "Socket send returned Network::Errno {}", err);
+            return -1;
+        }
+    }
+
+    static int ReadCallback(BIO* bio, char* buf, size_t len, size_t* actual_p) {
+        auto self = static_cast<SSLConnectionBackendOpenSSL*>(BIO_get_data(bio));
+        ASSERT_OR_EXECUTE_MSG(
+            self->socket_, { return 0; }, "OpenSSL asked to recv but we have no socket");
+        BIO_clear_retry_flags(bio);
+        auto [actual, err] = self->socket_->Recv(0, {reinterpret_cast<u8*>(buf), len});
+        switch (err) {
+        case Network::Errno::SUCCESS:
+            *actual_p = actual;
+            if (actual == 0) {
+                self->got_read_eof_ = true;
+            }
+            return actual ? 1 : 0;
+        case Network::Errno::AGAIN:
+            BIO_set_flags(bio, BIO_FLAGS_READ | BIO_FLAGS_SHOULD_RETRY);
+            return 0;
+        default:
+            LOG_ERROR(Service_SSL, "Socket recv returned Network::Errno {}", err);
+            return -1;
+        }
+    }
+
+    static long CtrlCallback(BIO* bio, int cmd, long larg, void* parg) {
+        switch (cmd) {
+        case BIO_CTRL_FLUSH:
+            // Nothing to flush.
+            return 1;
+        case BIO_CTRL_PUSH:
+        case BIO_CTRL_POP:
+        case BIO_CTRL_GET_KTLS_SEND:
+        case BIO_CTRL_GET_KTLS_RECV:
+            // We don't support these operations, but don't bother logging them
+            // as they're nothing unusual.
+            return 0;
+        default:
+            LOG_DEBUG(Service_SSL, "OpenSSL BIO got ctrl({}, {}, {})", cmd, larg, parg);
+            return 0;
+        }
+    }
+
+    SSL* ssl_ = nullptr;
+    BIO* bio_ = nullptr;
+    bool got_read_eof_ = false;
+
+    std::shared_ptr<Network::SocketBase> socket_;
+};
+
+ResultVal<std::unique_ptr<SSLConnectionBackend>> CreateSSLConnectionBackend() {
+    auto conn = std::make_unique<SSLConnectionBackendOpenSSL>();
+    Result res = conn->Init();
+    if (res.IsFailure()) {
+        return res;
+    }
+    return conn;
+}
+
+namespace {
+
+Result CheckOpenSSLErrors() {
+    unsigned long rc;
+    const char* file;
+    int line;
+    const char* func;
+    const char* data;
+    int flags;
+    while ((rc = ERR_get_error_all(&file, &line, &func, &data, &flags))) {
+        std::string msg;
+        msg.resize(1024, '\0');
+        ERR_error_string_n(rc, msg.data(), msg.size());
+        msg.resize(strlen(msg.data()), '\0');
+        if (flags & ERR_TXT_STRING) {
+            msg.append(" | ");
+            msg.append(data);
+        }
+        Common::Log::FmtLogMessage(Common::Log::Class::Service_SSL, Common::Log::Level::Error,
+                                   Common::Log::TrimSourcePath(file), line, func, "OpenSSL: {}",
+                                   msg);
+    }
+    return ResultInternalError;
+}
+
+void OneTimeInit() {
+    ssl_ctx = SSL_CTX_new(TLS_client_method());
+    if (!ssl_ctx) {
+        LOG_ERROR(Service_SSL, "SSL_CTX_new failed");
+        CheckOpenSSLErrors();
+        return;
+    }
+
+    SSL_CTX_set_verify(ssl_ctx, SSL_VERIFY_PEER, nullptr);
+
+    if (!SSL_CTX_set_default_verify_paths(ssl_ctx)) {
+        LOG_ERROR(Service_SSL, "SSL_CTX_set_default_verify_paths failed");
+        CheckOpenSSLErrors();
+        return;
+    }
+
+    OneTimeInitLogFile();
+
+    if (!OneTimeInitBIO()) {
+        return;
+    }
+
+    one_time_init_success = true;
+}
+
+void OneTimeInitLogFile() {
+    const char* logfile = getenv("SSLKEYLOGFILE");
+    if (logfile) {
+        key_log_file.Open(logfile, FileAccessMode::Append, FileType::TextFile,
+                          FileShareFlag::ShareWriteOnly);
+        if (key_log_file.IsOpen()) {
+            SSL_CTX_set_keylog_callback(ssl_ctx, &SSLConnectionBackendOpenSSL::KeyLogCallback);
+        } else {
+            LOG_CRITICAL(Service_SSL,
+                         "SSLKEYLOGFILE was set but file could not be opened; not logging keys!");
+        }
+    }
+}
+
+bool OneTimeInitBIO() {
+    bio_meth =
+        BIO_meth_new(BIO_get_new_index() | BIO_TYPE_SOURCE_SINK, "SSLConnectionBackendOpenSSL");
+    if (!bio_meth ||
+        !BIO_meth_set_write_ex(bio_meth, &SSLConnectionBackendOpenSSL::WriteCallback) ||
+        !BIO_meth_set_read_ex(bio_meth, &SSLConnectionBackendOpenSSL::ReadCallback) ||
+        !BIO_meth_set_ctrl(bio_meth, &SSLConnectionBackendOpenSSL::CtrlCallback)) {
+        LOG_ERROR(Service_SSL, "Failed to create BIO_METHOD");
+        return false;
+    }
+    return true;
+}
+
+} // namespace
+
+} // namespace Service::SSL

src/core/hle/service/ssl/ssl_backend_schannel.cpp

@@ -0,0 +1,529 @@
+// SPDX-FileCopyrightText: Copyright 2023 yuzu Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include "core/hle/service/ssl/ssl_backend.h"
+#include "core/internal_network/network.h"
+#include "core/internal_network/sockets.h"
+
+#include "common/error.h"
+#include "common/fs/file.h"
+#include "common/hex_util.h"
+#include "common/string_util.h"
+
+#include <mutex>
+
+#define SECURITY_WIN32
+#include <Security.h>
+#include <schnlsp.h>
+
+namespace {
+
+std::once_flag one_time_init_flag;
+bool one_time_init_success = false;
+
+SCHANNEL_CRED schannel_cred{
+    .dwVersion = SCHANNEL_CRED_VERSION,
+    .dwFlags = SCH_USE_STRONG_CRYPTO |         // don't allow insecure protocols
+               SCH_CRED_AUTO_CRED_VALIDATION | // validate certs
+               SCH_CRED_NO_DEFAULT_CREDS,      // don't automatically present a client certificate
+    // ^ I'm assuming that nobody would want to connect Yuzu to a
+    // service that requires some OS-provided corporate client
+    // certificate, and presenting one to some arbitrary server
+    // might be a privacy concern?  Who knows, though.
+};
+
+CredHandle cred_handle;
+
+static void OneTimeInit() {
+    SECURITY_STATUS ret =
+        AcquireCredentialsHandle(nullptr, const_cast<LPTSTR>(UNISP_NAME), SECPKG_CRED_OUTBOUND,
+                                 nullptr, &schannel_cred, nullptr, nullptr, &cred_handle, nullptr);
+    if (ret != SEC_E_OK) {
+        // SECURITY_STATUS codes are a type of HRESULT and can be used with NativeErrorToString.
+        LOG_ERROR(Service_SSL, "AcquireCredentialsHandle failed: {}",
+                  Common::NativeErrorToString(ret));
+        return;
+    }
+
+    one_time_init_success = true;
+}
+
+} // namespace
+
+namespace Service::SSL {
+
+class SSLConnectionBackendSchannel final : public SSLConnectionBackend {
+public:
+    Result Init() {
+        std::call_once(one_time_init_flag, OneTimeInit);
+
+        if (!one_time_init_success) {
+            LOG_ERROR(
+                Service_SSL,
+                "Can't create SSL connection because Schannel one-time initialization failed");
+            return ResultInternalError;
+        }
+
+        return ResultSuccess;
+    }
+
+    void SetSocket(std::shared_ptr<Network::SocketBase> socket) override {
+        socket_ = socket;
+    }
+
+    Result SetHostName(const std::string& hostname) override {
+        hostname_ = hostname;
+        return ResultSuccess;
+    }
+
+    Result DoHandshake() override {
+        while (1) {
+            Result r;
+            switch (handshake_state_) {
+            case HandshakeState::Initial:
+                if ((r = FlushCiphertextWriteBuf()) != ResultSuccess ||
+                    (r = CallInitializeSecurityContext()) != ResultSuccess) {
+                    return r;
+                }
+                // CallInitializeSecurityContext updated `handshake_state_`.
+                continue;
+            case HandshakeState::ContinueNeeded:
+            case HandshakeState::IncompleteMessage:
+                if ((r = FlushCiphertextWriteBuf()) != ResultSuccess ||
+                    (r = FillCiphertextReadBuf()) != ResultSuccess) {
+                    return r;
+                }
+                if (ciphertext_read_buf_.empty()) {
+                    LOG_ERROR(Service_SSL, "SSL handshake failed because server hung up");
+                    return ResultInternalError;
+                }
+                if ((r = CallInitializeSecurityContext()) != ResultSuccess) {
+                    return r;
+                }
+                // CallInitializeSecurityContext updated `handshake_state_`.
+                continue;
+            case HandshakeState::DoneAfterFlush:
+                if ((r = FlushCiphertextWriteBuf()) != ResultSuccess) {
+                    return r;
+                }
+                handshake_state_ = HandshakeState::Connected;
+                return ResultSuccess;
+            case HandshakeState::Connected:
+                LOG_ERROR(Service_SSL, "Called DoHandshake but we already handshook");
+                return ResultInternalError;
+            case HandshakeState::Error:
+                return ResultInternalError;
+            }
+        }
+    }
+
+    Result FillCiphertextReadBuf() {
+        size_t fill_size = read_buf_fill_size_ ? read_buf_fill_size_ : 4096;
+        read_buf_fill_size_ = 0;
+        // This unnecessarily zeroes the buffer; oh well.
+        size_t offset = ciphertext_read_buf_.size();
+        ASSERT_OR_EXECUTE(offset + fill_size >= offset, { return ResultInternalError; });
+        ciphertext_read_buf_.resize(offset + fill_size, 0);
+        auto read_span = std::span(ciphertext_read_buf_).subspan(offset, fill_size);
+        auto [actual, err] = socket_->Recv(0, read_span);
+        switch (err) {
+        case Network::Errno::SUCCESS:
+            ASSERT(static_cast<size_t>(actual) <= fill_size);
+            ciphertext_read_buf_.resize(offset + actual);
+            return ResultSuccess;
+        case Network::Errno::AGAIN:
+            ciphertext_read_buf_.resize(offset);
+            return ResultWouldBlock;
+        default:
+            ciphertext_read_buf_.resize(offset);
+            LOG_ERROR(Service_SSL, "Socket recv returned Network::Errno {}", err);
+            return ResultInternalError;
+        }
+    }
+
+    // Returns success if the write buffer has been completely emptied.
+    Result FlushCiphertextWriteBuf() {
+        while (!ciphertext_write_buf_.empty()) {
+            auto [actual, err] = socket_->Send(ciphertext_write_buf_, 0);
+            switch (err) {
+            case Network::Errno::SUCCESS:
+                ASSERT(static_cast<size_t>(actual) <= ciphertext_write_buf_.size());
+                ciphertext_write_buf_.erase(ciphertext_write_buf_.begin(),
+                                            ciphertext_write_buf_.begin() + actual);
+                break;
+            case Network::Errno::AGAIN:
+                return ResultWouldBlock;
+            default:
+                LOG_ERROR(Service_SSL, "Socket send returned Network::Errno {}", err);
+                return ResultInternalError;
+            }
+        }
+        return ResultSuccess;
+    }
+
+    Result CallInitializeSecurityContext() {
+        unsigned long req = ISC_REQ_ALLOCATE_MEMORY | ISC_REQ_CONFIDENTIALITY | ISC_REQ_INTEGRITY |
+                            ISC_REQ_REPLAY_DETECT | ISC_REQ_SEQUENCE_DETECT | ISC_REQ_STREAM |
+                            ISC_REQ_USE_SUPPLIED_CREDS;
+        unsigned long attr;
+        // https://learn.microsoft.com/en-us/windows/win32/secauthn/initializesecuritycontext--schannel
+        std::array<SecBuffer, 2> input_buffers{{
+            // only used if `initial_call_done`
+            {
+                // [0]
+                .cbBuffer = static_cast<unsigned long>(ciphertext_read_buf_.size()),
+                .BufferType = SECBUFFER_TOKEN,
+                .pvBuffer = ciphertext_read_buf_.data(),
+            },
+            {
+                // [1] (will be replaced by SECBUFFER_MISSING when SEC_E_INCOMPLETE_MESSAGE is
+                //     returned, or SECBUFFER_EXTRA when SEC_E_CONTINUE_NEEDED is returned if the
+                //     whole buffer wasn't used)
+                .BufferType = SECBUFFER_EMPTY,
+            },
+        }};
+        std::array<SecBuffer, 2> output_buffers{{
+            {
+                .BufferType = SECBUFFER_TOKEN,
+            }, // [0]
+            {
+                .BufferType = SECBUFFER_ALERT,
+            }, // [1]
+        }};
+        SecBufferDesc input_desc{
+            .ulVersion = SECBUFFER_VERSION,
+            .cBuffers = static_cast<unsigned long>(input_buffers.size()),
+            .pBuffers = input_buffers.data(),
+        };
+        SecBufferDesc output_desc{
+            .ulVersion = SECBUFFER_VERSION,
+            .cBuffers = static_cast<unsigned long>(output_buffers.size()),
+            .pBuffers = output_buffers.data(),
+        };
+        ASSERT_OR_EXECUTE_MSG(
+            input_buffers[0].cbBuffer == ciphertext_read_buf_.size(),
+            { return ResultInternalError; }, "read buffer too large");
+
+        bool initial_call_done = handshake_state_ != HandshakeState::Initial;
+        if (initial_call_done) {
+            LOG_DEBUG(Service_SSL, "Passing {} bytes into InitializeSecurityContext",
+                      ciphertext_read_buf_.size());
+        }
+
+        SECURITY_STATUS ret =
+            InitializeSecurityContextA(&cred_handle, initial_call_done ? &ctxt_ : nullptr,
+                                       // Caller ensured we have set a hostname:
+                                       const_cast<char*>(hostname_.value().c_str()), req,
+                                       0, // Reserved1
+                                       0, // TargetDataRep not used with Schannel
+                                       initial_call_done ? &input_desc : nullptr,
+                                       0, // Reserved2
+                                       initial_call_done ? nullptr : &ctxt_, &output_desc, &attr,
+                                       nullptr); // ptsExpiry
+
+        if (output_buffers[0].pvBuffer) {
+            std::span span(static_cast<u8*>(output_buffers[0].pvBuffer),
+                           output_buffers[0].cbBuffer);
+            ciphertext_write_buf_.insert(ciphertext_write_buf_.end(), span.begin(), span.end());
+            FreeContextBuffer(output_buffers[0].pvBuffer);
+        }
+
+        if (output_buffers[1].pvBuffer) {
+            std::span span(static_cast<u8*>(output_buffers[1].pvBuffer),
+                           output_buffers[1].cbBuffer);
+            // The documentation doesn't explain what format this data is in.
+            LOG_DEBUG(Service_SSL, "Got a {}-byte alert buffer: {}", span.size(),
+                      Common::HexToString(span));
+        }
+
+        switch (ret) {
+        case SEC_I_CONTINUE_NEEDED:
+            LOG_DEBUG(Service_SSL, "InitializeSecurityContext => SEC_I_CONTINUE_NEEDED");
+            if (input_buffers[1].BufferType == SECBUFFER_EXTRA) {
+                LOG_DEBUG(Service_SSL, "EXTRA of size {}", input_buffers[1].cbBuffer);
+                ASSERT(input_buffers[1].cbBuffer <= ciphertext_read_buf_.size());
+                ciphertext_read_buf_.erase(ciphertext_read_buf_.begin(),
+                                           ciphertext_read_buf_.end() - input_buffers[1].cbBuffer);
+            } else {
+                ASSERT(input_buffers[1].BufferType == SECBUFFER_EMPTY);
+                ciphertext_read_buf_.clear();
+            }
+            handshake_state_ = HandshakeState::ContinueNeeded;
+            return ResultSuccess;
+        case SEC_E_INCOMPLETE_MESSAGE:
+            LOG_DEBUG(Service_SSL, "InitializeSecurityContext => SEC_E_INCOMPLETE_MESSAGE");
+            ASSERT(input_buffers[1].BufferType == SECBUFFER_MISSING);
+            read_buf_fill_size_ = input_buffers[1].cbBuffer;
+            handshake_state_ = HandshakeState::IncompleteMessage;
+            return ResultSuccess;
+        case SEC_E_OK:
+            LOG_DEBUG(Service_SSL, "InitializeSecurityContext => SEC_E_OK");
+            ciphertext_read_buf_.clear();
+            handshake_state_ = HandshakeState::DoneAfterFlush;
+            return GrabStreamSizes();
+        default:
+            LOG_ERROR(Service_SSL,
+                      "InitializeSecurityContext failed (probably certificate/protocol issue): {}",
+                      Common::NativeErrorToString(ret));
+            handshake_state_ = HandshakeState::Error;
+            return ResultInternalError;
+        }
+    }
+
+    Result GrabStreamSizes() {
+        SECURITY_STATUS ret =
+            QueryContextAttributes(&ctxt_, SECPKG_ATTR_STREAM_SIZES, &stream_sizes_);
+        if (ret != SEC_E_OK) {
+            LOG_ERROR(Service_SSL, "QueryContextAttributes(SECPKG_ATTR_STREAM_SIZES) failed: {}",
+                      Common::NativeErrorToString(ret));
+            handshake_state_ = HandshakeState::Error;
+            return ResultInternalError;
+        }
+        return ResultSuccess;
+    }
+
+    ResultVal<size_t> Read(std::span<u8> data) override {
+        if (handshake_state_ != HandshakeState::Connected) {
+            LOG_ERROR(Service_SSL, "Called Read but we did not successfully handshake");
+            return ResultInternalError;
+        }
+        if (data.size() == 0 || got_read_eof_) {
+            return size_t(0);
+        }
+        while (1) {
+            if (!cleartext_read_buf_.empty()) {
+                size_t read_size = std::min(cleartext_read_buf_.size(), data.size());
+                std::memcpy(data.data(), cleartext_read_buf_.data(), read_size);
+                cleartext_read_buf_.erase(cleartext_read_buf_.begin(),
+                                          cleartext_read_buf_.begin() + read_size);
+                return read_size;
+            }
+            if (!ciphertext_read_buf_.empty()) {
+                std::array<SecBuffer, 5> buffers{{
+                    {
+                        .cbBuffer = static_cast<unsigned long>(ciphertext_read_buf_.size()),
+                        .BufferType = SECBUFFER_DATA,
+                        .pvBuffer = ciphertext_read_buf_.data(),
+                    },
+                    {
+                        .BufferType = SECBUFFER_EMPTY,
+                    },
+                    {
+                        .BufferType = SECBUFFER_EMPTY,
+                    },
+                    {
+                        .BufferType = SECBUFFER_EMPTY,
+                    },
+                }};
+                ASSERT_OR_EXECUTE_MSG(
+                    buffers[0].cbBuffer == ciphertext_read_buf_.size(),
+                    { return ResultInternalError; }, "read buffer too large");
+                SecBufferDesc desc{
+                    .ulVersion = SECBUFFER_VERSION,
+                    .cBuffers = static_cast<unsigned long>(buffers.size()),
+                    .pBuffers = buffers.data(),
+                };
+                SECURITY_STATUS ret =
+                    DecryptMessage(&ctxt_, &desc, /*MessageSeqNo*/ 0, /*pfQOP*/ nullptr);
+                switch (ret) {
+                case SEC_E_OK:
+                    ASSERT_OR_EXECUTE(buffers[0].BufferType == SECBUFFER_STREAM_HEADER,
+                                      { return ResultInternalError; });
+                    ASSERT_OR_EXECUTE(buffers[1].BufferType == SECBUFFER_DATA,
+                                      { return ResultInternalError; });
+                    ASSERT_OR_EXECUTE(buffers[2].BufferType == SECBUFFER_STREAM_TRAILER,
+                                      { return ResultInternalError; });
+                    cleartext_read_buf_.assign(static_cast<u8*>(buffers[1].pvBuffer),
+                                               static_cast<u8*>(buffers[1].pvBuffer) +
+                                                   buffers[1].cbBuffer);
+                    if (buffers[3].BufferType == SECBUFFER_EXTRA) {
+                        ASSERT(buffers[3].cbBuffer <= ciphertext_read_buf_.size());
+                        ciphertext_read_buf_.erase(ciphertext_read_buf_.begin(),
+                                                   ciphertext_read_buf_.end() -
+                                                       buffers[3].cbBuffer);
+                    } else {
+                        ASSERT(buffers[3].BufferType == SECBUFFER_EMPTY);
+                        ciphertext_read_buf_.clear();
+                    }
+                    continue;
+                case SEC_E_INCOMPLETE_MESSAGE:
+                    break;
+                case SEC_I_CONTEXT_EXPIRED:
+                    // Server hung up by sending close_notify.
+                    got_read_eof_ = true;
+                    return size_t(0);
+                default:
+                    LOG_ERROR(Service_SSL, "DecryptMessage failed: {}",
+                              Common::NativeErrorToString(ret));
+                    return ResultInternalError;
+                }
+            }
+            Result r = FillCiphertextReadBuf();
+            if (r != ResultSuccess) {
+                return r;
+            }
+            if (ciphertext_read_buf_.empty()) {
+                got_read_eof_ = true;
+                return size_t(0);
+            }
+        }
+    }
+
+    ResultVal<size_t> Write(std::span<const u8> data) override {
+        if (handshake_state_ != HandshakeState::Connected) {
+            LOG_ERROR(Service_SSL, "Called Write but we did not successfully handshake");
+            return ResultInternalError;
+        }
+        if (data.size() == 0) {
+            return size_t(0);
+        }
+        data = data.subspan(0, std::min<size_t>(data.size(), stream_sizes_.cbMaximumMessage));
+        if (!cleartext_write_buf_.empty()) {
+            // Already in the middle of a write.  It wouldn't make sense to not
+            // finish sending the entire buffer since TLS has
+            // header/MAC/padding/etc.
+            if (data.size() != cleartext_write_buf_.size() ||
+                std::memcmp(data.data(), cleartext_write_buf_.data(), data.size())) {
+                LOG_ERROR(Service_SSL, "Called Write but buffer does not match previous buffer");
+                return ResultInternalError;
+            }
+            return WriteAlreadyEncryptedData();
+        } else {
+            cleartext_write_buf_.assign(data.begin(), data.end());
+        }
+
+        std::vector<u8> header_buf(stream_sizes_.cbHeader, 0);
+        std::vector<u8> tmp_data_buf = cleartext_write_buf_;
+        std::vector<u8> trailer_buf(stream_sizes_.cbTrailer, 0);
+
+        std::array<SecBuffer, 3> buffers{{
+            {
+                .cbBuffer = stream_sizes_.cbHeader,
+                .BufferType = SECBUFFER_STREAM_HEADER,
+                .pvBuffer = header_buf.data(),
+            },
+            {
+                .cbBuffer = static_cast<unsigned long>(tmp_data_buf.size()),
+                .BufferType = SECBUFFER_DATA,
+                .pvBuffer = tmp_data_buf.data(),
+            },
+            {
+                .cbBuffer = stream_sizes_.cbTrailer,
+                .BufferType = SECBUFFER_STREAM_TRAILER,
+                .pvBuffer = trailer_buf.data(),
+            },
+        }};
+        ASSERT_OR_EXECUTE_MSG(
+            buffers[1].cbBuffer == tmp_data_buf.size(), { return ResultInternalError; },
+            "temp buffer too large");
+        SecBufferDesc desc{
+            .ulVersion = SECBUFFER_VERSION,
+            .cBuffers = static_cast<unsigned long>(buffers.size()),
+            .pBuffers = buffers.data(),
+        };
+
+        SECURITY_STATUS ret = EncryptMessage(&ctxt_, /*fQOP*/ 0, &desc, /*MessageSeqNo*/ 0);
+        if (ret != SEC_E_OK) {
+            LOG_ERROR(Service_SSL, "EncryptMessage failed: {}", Common::NativeErrorToString(ret));
+            return ResultInternalError;
+        }
+        ciphertext_write_buf_.insert(ciphertext_write_buf_.end(), header_buf.begin(),
+                                     header_buf.end());
+        ciphertext_write_buf_.insert(ciphertext_write_buf_.end(), tmp_data_buf.begin(),
+                                     tmp_data_buf.end());
+        ciphertext_write_buf_.insert(ciphertext_write_buf_.end(), trailer_buf.begin(),
+                                     trailer_buf.end());
+        return WriteAlreadyEncryptedData();
+    }
+
+    ResultVal<size_t> WriteAlreadyEncryptedData() {
+        Result r = FlushCiphertextWriteBuf();
+        if (r != ResultSuccess) {
+            return r;
+        }
+        // write buf is empty
+        size_t cleartext_bytes_written = cleartext_write_buf_.size();
+        cleartext_write_buf_.clear();
+        return cleartext_bytes_written;
+    }
+
+    ResultVal<std::vector<std::vector<u8>>> GetServerCerts() override {
+        PCCERT_CONTEXT returned_cert = nullptr;
+        SECURITY_STATUS ret =
+            QueryContextAttributes(&ctxt_, SECPKG_ATTR_REMOTE_CERT_CONTEXT, &returned_cert);
+        if (ret != SEC_E_OK) {
+            LOG_ERROR(Service_SSL,
+                      "QueryContextAttributes(SECPKG_ATTR_REMOTE_CERT_CONTEXT) failed: {}",
+                      Common::NativeErrorToString(ret));
+            return ResultInternalError;
+        }
+        PCCERT_CONTEXT some_cert = nullptr;
+        std::vector<std::vector<u8>> certs;
+        while ((some_cert = CertEnumCertificatesInStore(returned_cert->hCertStore, some_cert))) {
+            certs.emplace_back(static_cast<u8*>(some_cert->pbCertEncoded),
+                               static_cast<u8*>(some_cert->pbCertEncoded) +
+                                   some_cert->cbCertEncoded);
+        }
+        std::reverse(certs.begin(),
+                     certs.end()); // Windows returns certs in reverse order from what we want
+        CertFreeCertificateContext(returned_cert);
+        return certs;
+    }
+
+    ~SSLConnectionBackendSchannel() {
+        if (handshake_state_ != HandshakeState::Initial) {
+            DeleteSecurityContext(&ctxt_);
+        }
+    }
+
+    enum class HandshakeState {
+        // Haven't called anything yet.
+        Initial,
+        // `SEC_I_CONTINUE_NEEDED` was returned by
+        // `InitializeSecurityContext`; must finish sending data (if any) in
+        // the write buffer, then read at least one byte before calling
+        // `InitializeSecurityContext` again.
+        ContinueNeeded,
+        // `SEC_E_INCOMPLETE_MESSAGE` was returned by
+        // `InitializeSecurityContext`; hopefully the write buffer is empty;
+        // must read at least one byte before calling
+        // `InitializeSecurityContext` again.
+        IncompleteMessage,
+        // `SEC_E_OK` was returned by `InitializeSecurityContext`; must
+        // finish sending data in the write buffer before having `DoHandshake`
+        // report success.
+        DoneAfterFlush,
+        // We finished the above and are now connected.  At this point, writing
+        // and reading are separate 'state machines' represented by the
+        // nonemptiness of the ciphertext and cleartext read and write buffers.
+        Connected,
+        // Another error was returned and we shouldn't allow initialization
+        // to continue.
+        Error,
+    } handshake_state_ = HandshakeState::Initial;
+
+    CtxtHandle ctxt_;
+    SecPkgContext_StreamSizes stream_sizes_;
+
+    std::shared_ptr<Network::SocketBase> socket_;
+    std::optional<std::string> hostname_;
+
+    std::vector<u8> ciphertext_read_buf_;
+    std::vector<u8> ciphertext_write_buf_;
+    std::vector<u8> cleartext_read_buf_;
+    std::vector<u8> cleartext_write_buf_;
+
+    bool got_read_eof_ = false;
+    size_t read_buf_fill_size_ = 0;
+};
+
+ResultVal<std::unique_ptr<SSLConnectionBackend>> CreateSSLConnectionBackend() {
+    auto conn = std::make_unique<SSLConnectionBackendSchannel>();
+    Result res = conn->Init();
+    if (res.IsFailure()) {
+        return res;
+    }
+    return conn;
+}
+
+} // namespace Service::SSL

src/core/internal_network/network.cpp

@@ -121,6 +121,8 @@ Errno TranslateNativeError(int e) {
         return Errno::MSGSIZE;
     case WSAETIMEDOUT:
         return Errno::TIMEDOUT;
+    case WSAEINPROGRESS:
+        return Errno::INPROGRESS;
     default:
         UNIMPLEMENTED_MSG("Unimplemented errno={}", e);
         return Errno::OTHER;
@@ -195,6 +197,8 @@ bool EnableNonBlock(int fd, bool enable) {
 
 Errno TranslateNativeError(int e) {
     switch (e) {
+    case 0:
+        return Errno::SUCCESS;
     case EBADF:
         return Errno::BADF;
     case EINVAL:
@@ -219,8 +223,10 @@ Errno TranslateNativeError(int e) {
         return Errno::MSGSIZE;
     case ETIMEDOUT:
         return Errno::TIMEDOUT;
+    case EINPROGRESS:
+        return Errno::INPROGRESS;
     default:
-        UNIMPLEMENTED_MSG("Unimplemented errno={}", e);
+        UNIMPLEMENTED_MSG("Unimplemented errno={} ({})", e, strerror(e));
         return Errno::OTHER;
     }
 }
@@ -234,15 +240,84 @@ Errno GetAndLogLastError() {
     int e = errno;
 #endif
     const Errno err = TranslateNativeError(e);
-    if (err == Errno::AGAIN || err == Errno::TIMEDOUT) {
+    if (err == Errno::AGAIN || err == Errno::TIMEDOUT || err == Errno::INPROGRESS) {
+        // These happen during normal operation, so only log them at debug level.
+        LOG_DEBUG(Network, "Socket operation error: {}", Common::NativeErrorToString(e));
         return err;
     }
     LOG_ERROR(Network, "Socket operation error: {}", Common::NativeErrorToString(e));
     return err;
 }
 
-int TranslateDomain(Domain domain) {
+GetAddrInfoError TranslateGetAddrInfoErrorFromNative(int gai_err) {
+    switch (gai_err) {
+    case 0:
+        return GetAddrInfoError::SUCCESS;
+#ifdef EAI_ADDRFAMILY
+    case EAI_ADDRFAMILY:
+        return GetAddrInfoError::ADDRFAMILY;
+#endif
+    case EAI_AGAIN:
+        return GetAddrInfoError::AGAIN;
+    case EAI_BADFLAGS:
+        return GetAddrInfoError::BADFLAGS;
+    case EAI_FAIL:
+        return GetAddrInfoError::FAIL;
+    case EAI_FAMILY:
+        return GetAddrInfoError::FAMILY;
+    case EAI_MEMORY:
+        return GetAddrInfoError::MEMORY;
+    case EAI_NONAME:
+        return GetAddrInfoError::NONAME;
+    case EAI_SERVICE:
+        return GetAddrInfoError::SERVICE;
+    case EAI_SOCKTYPE:
+        return GetAddrInfoError::SOCKTYPE;
+        // These codes may not be defined on all systems:
+#ifdef EAI_SYSTEM
+    case EAI_SYSTEM:
+        return GetAddrInfoError::SYSTEM;
+#endif
+#ifdef EAI_BADHINTS
+    case EAI_BADHINTS:
+        return GetAddrInfoError::BADHINTS;
+#endif
+#ifdef EAI_PROTOCOL
+    case EAI_PROTOCOL:
+        return GetAddrInfoError::PROTOCOL;
+#endif
+#ifdef EAI_OVERFLOW
+    case EAI_OVERFLOW:
+        return GetAddrInfoError::OVERFLOW_;
+#endif
+    default:
+#ifdef EAI_NODATA
+        // This can't be a case statement because it would create a duplicate
+        // case on Windows where EAI_NODATA is an alias for EAI_NONAME.
+        if (gai_err == EAI_NODATA) {
+            return GetAddrInfoError::NODATA;
+        }
+#endif
+        return GetAddrInfoError::OTHER;
+    }
+}
+
+Domain TranslateDomainFromNative(int domain) {
     switch (domain) {
+    case 0:
+        return Domain::Unspecified;
+    case AF_INET:
+        return Domain::INET;
+    default:
+        UNIMPLEMENTED_MSG("Unhandled domain={}", domain);
+        return Domain::INET;
+    }
+}
+
+int TranslateDomainToNative(Domain domain) {
+    switch (domain) {
+    case Domain::Unspecified:
+        return 0;
     case Domain::INET:
         return AF_INET;
     default:
@@ -251,20 +326,58 @@ int TranslateDomain(Domain domain) {
     }
 }
 
-int TranslateType(Type type) {
+Type TranslateTypeFromNative(int type) {
     switch (type) {
+    case 0:
+        return Type::Unspecified;
+    case SOCK_STREAM:
+        return Type::STREAM;
+    case SOCK_DGRAM:
+        return Type::DGRAM;
+    case SOCK_RAW:
+        return Type::RAW;
+    case SOCK_SEQPACKET:
+        return Type::SEQPACKET;
+    default:
+        UNIMPLEMENTED_MSG("Unimplemented type={}", type);
+        return Type::STREAM;
+    }
+}
+
+int TranslateTypeToNative(Type type) {
+    switch (type) {
+    case Type::Unspecified:
+        return 0;
     case Type::STREAM:
         return SOCK_STREAM;
     case Type::DGRAM:
         return SOCK_DGRAM;
+    case Type::RAW:
+        return SOCK_RAW;
     default:
         UNIMPLEMENTED_MSG("Unimplemented type={}", type);
         return 0;
     }
 }
 
-int TranslateProtocol(Protocol protocol) {
+Protocol TranslateProtocolFromNative(int protocol) {
     switch (protocol) {
+    case 0:
+        return Protocol::Unspecified;
+    case IPPROTO_TCP:
+        return Protocol::TCP;
+    case IPPROTO_UDP:
+        return Protocol::UDP;
+    default:
+        UNIMPLEMENTED_MSG("Unimplemented protocol={}", protocol);
+        return Protocol::Unspecified;
+    }
+}
+
+int TranslateProtocolToNative(Protocol protocol) {
+    switch (protocol) {
+    case Protocol::Unspecified:
+        return 0;
     case Protocol::TCP:
         return IPPROTO_TCP;
     case Protocol::UDP:
@@ -275,21 +388,10 @@ int TranslateProtocol(Protocol protocol) {
     }
 }
 
-SockAddrIn TranslateToSockAddrIn(sockaddr input_) {
+SockAddrIn TranslateToSockAddrIn(sockaddr_in input, size_t input_len) {
-    sockaddr_in input;
-    std::memcpy(&input, &input_, sizeof(input));
-
     SockAddrIn result;
 
-    switch (input.sin_family) {
+    result.family = TranslateDomainFromNative(input.sin_family);
-    case AF_INET:
-        result.family = Domain::INET;
-        break;
-    default:
-        UNIMPLEMENTED_MSG("Unhandled sockaddr family={}", input.sin_family);
-        result.family = Domain::INET;
-        break;
-    }
 
     result.portno = ntohs(input.sin_port);
 
@@ -301,22 +403,28 @@ SockAddrIn TranslateToSockAddrIn(sockaddr input_) {
 short TranslatePollEvents(PollEvents events) {
     short result = 0;
 
-    if (True(events & PollEvents::In)) {
+    const auto translate = [&result, &events](PollEvents guest, short host) {
-        events &= ~PollEvents::In;
+        if (True(events & guest)) {
-        result |= POLLIN;
+            events &= ~guest;
-    }
+            result |= host;
-    if (True(events & PollEvents::Pri)) {
+        }
-        events &= ~PollEvents::Pri;
+    };
+
+    translate(PollEvents::In, POLLIN);
+    translate(PollEvents::Pri, POLLPRI);
+    translate(PollEvents::Out, POLLOUT);
+    translate(PollEvents::Err, POLLERR);
+    translate(PollEvents::Hup, POLLHUP);
+    translate(PollEvents::Nval, POLLNVAL);
+    translate(PollEvents::RdNorm, POLLRDNORM);
+    translate(PollEvents::RdBand, POLLRDBAND);
+    translate(PollEvents::WrBand, POLLWRBAND);
+
 #ifdef _WIN32
+    if (True(events & PollEvents::Pri)) {
         LOG_WARNING(Service, "Winsock doesn't support POLLPRI");
-#else
+    }
-        result |= POLLPRI;
 #endif
-    }
-    if (True(events & PollEvents::Out)) {
-        events &= ~PollEvents::Out;
-        result |= POLLOUT;
-    }
 
     UNIMPLEMENTED_IF_MSG((u16)events != 0, "Unhandled guest events=0x{:x}", (u16)events);
 
@@ -337,6 +445,10 @@ PollEvents TranslatePollRevents(short revents) {
     translate(POLLOUT, PollEvents::Out);
     translate(POLLERR, PollEvents::Err);
     translate(POLLHUP, PollEvents::Hup);
+    translate(POLLNVAL, PollEvents::Nval);
+    translate(POLLRDNORM, PollEvents::RdNorm);
+    translate(POLLRDBAND, PollEvents::RdBand);
+    translate(POLLWRBAND, PollEvents::WrBand);
 
     UNIMPLEMENTED_IF_MSG(revents != 0, "Unhandled host revents=0x{:x}", revents);
 
@@ -360,12 +472,53 @@ std::optional<IPv4Address> GetHostIPv4Address() {
         return {};
     }
 
-    std::array<char, 16> ip_addr = {};
-    ASSERT(inet_ntop(AF_INET, &network_interface->ip_address, ip_addr.data(), sizeof(ip_addr)) !=
-           nullptr);
     return TranslateIPv4(network_interface->ip_address);
 }
 
+std::string IPv4AddressToString(IPv4Address ip_addr) {
+    std::array<char, INET_ADDRSTRLEN> buf = {};
+    ASSERT(inet_ntop(AF_INET, &ip_addr, buf.data(), sizeof(buf)) == buf.data());
+    return std::string(buf.data());
+}
+
+u32 IPv4AddressToInteger(IPv4Address ip_addr) {
+    return static_cast<u32>(ip_addr[0]) << 24 | static_cast<u32>(ip_addr[1]) << 16 |
+           static_cast<u32>(ip_addr[2]) << 8 | static_cast<u32>(ip_addr[3]);
+}
+
+#undef GetAddrInfo // Windows defines it as a macro
+
+Common::Expected<std::vector<AddrInfo>, GetAddrInfoError> GetAddrInfo(
+    const std::string& host, const std::optional<std::string>& service) {
+    addrinfo hints{};
+    hints.ai_family = AF_INET; // Switch only supports IPv4.
+    addrinfo* addrinfo;
+    s32 gai_err = getaddrinfo(host.c_str(), service.has_value() ? service->c_str() : nullptr,
+                              &hints, &addrinfo);
+    if (gai_err != 0) {
+        return Common::Unexpected(TranslateGetAddrInfoErrorFromNative(gai_err));
+    }
+    std::vector<AddrInfo> ret;
+    for (auto* current = addrinfo; current; current = current->ai_next) {
+        // We should only get AF_INET results due to the hints value.
+        ASSERT_OR_EXECUTE(addrinfo->ai_family == AF_INET &&
+                              addrinfo->ai_addrlen == sizeof(sockaddr_in),
+                          continue;);
+
+        AddrInfo& out = ret.emplace_back();
+        out.family = TranslateDomainFromNative(current->ai_family);
+        out.socket_type = TranslateTypeFromNative(current->ai_socktype);
+        out.protocol = TranslateProtocolFromNative(current->ai_protocol);
+        out.addr = TranslateToSockAddrIn(*reinterpret_cast<sockaddr_in*>(current->ai_addr),
+                                         current->ai_addrlen);
+        if (current->ai_canonname != nullptr) {
+            out.canon_name = current->ai_canonname;
+        }
+    }
+    freeaddrinfo(addrinfo);
+    return ret;
+}
+
 std::pair<s32, Errno> Poll(std::vector<PollFD>& pollfds, s32 timeout) {
     const size_t num = pollfds.size();
 
@@ -410,6 +563,18 @@ Socket::Socket(Socket&& rhs) noexcept {
     fd = std::exchange(rhs.fd, INVALID_SOCKET);
 }
 
+template <typename T>
+std::pair<T, Errno> Socket::GetSockOpt(SOCKET fd_, int option) {
+    T value{};
+    socklen_t len = sizeof(value);
+    const int result = getsockopt(fd_, SOL_SOCKET, option, reinterpret_cast<char*>(&value), &len);
+    if (result != SOCKET_ERROR) {
+        ASSERT(len == sizeof(value));
+        return {value, Errno::SUCCESS};
+    }
+    return {value, GetAndLogLastError()};
+}
+
 template <typename T>
 Errno Socket::SetSockOpt(SOCKET fd_, int option, T value) {
     const int result =
@@ -421,7 +586,8 @@ Errno Socket::SetSockOpt(SOCKET fd_, int option, T value) {
 }
 
 Errno Socket::Initialize(Domain domain, Type type, Protocol protocol) {
-    fd = socket(TranslateDomain(domain), TranslateType(type), TranslateProtocol(protocol));
+    fd = socket(TranslateDomainToNative(domain), TranslateTypeToNative(type),
+                TranslateProtocolToNative(protocol));
     if (fd != INVALID_SOCKET) {
         return Errno::SUCCESS;
     }
@@ -430,19 +596,17 @@ Errno Socket::Initialize(Domain domain, Type type, Protocol protocol) {
 }
 
 std::pair<SocketBase::AcceptResult, Errno> Socket::Accept() {
-    sockaddr addr;
+    sockaddr_in addr;
     socklen_t addrlen = sizeof(addr);
-    const SOCKET new_socket = accept(fd, &addr, &addrlen);
+    const SOCKET new_socket = accept(fd, reinterpret_cast<sockaddr*>(&addr), &addrlen);
 
     if (new_socket == INVALID_SOCKET) {
         return {AcceptResult{}, GetAndLogLastError()};
     }
 
-    ASSERT(addrlen == sizeof(sockaddr_in));
-
     AcceptResult result{
         .socket = std::make_unique<Socket>(new_socket),
-        .sockaddr_in = TranslateToSockAddrIn(addr),
+        .sockaddr_in = TranslateToSockAddrIn(addr, addrlen),
     };
 
     return {std::move(result), Errno::SUCCESS};
@@ -458,25 +622,23 @@ Errno Socket::Connect(SockAddrIn addr_in) {
 }
 
 std::pair<SockAddrIn, Errno> Socket::GetPeerName() {
-    sockaddr addr;
+    sockaddr_in addr;
     socklen_t addrlen = sizeof(addr);
-    if (getpeername(fd, &addr, &addrlen) == SOCKET_ERROR) {
+    if (getpeername(fd, reinterpret_cast<sockaddr*>(&addr), &addrlen) == SOCKET_ERROR) {
         return {SockAddrIn{}, GetAndLogLastError()};
     }
 
-    ASSERT(addrlen == sizeof(sockaddr_in));
+    return {TranslateToSockAddrIn(addr, addrlen), Errno::SUCCESS};
-    return {TranslateToSockAddrIn(addr), Errno::SUCCESS};
 }
 
 std::pair<SockAddrIn, Errno> Socket::GetSockName() {
-    sockaddr addr;
+    sockaddr_in addr;
     socklen_t addrlen = sizeof(addr);
-    if (getsockname(fd, &addr, &addrlen) == SOCKET_ERROR) {
+    if (getsockname(fd, reinterpret_cast<sockaddr*>(&addr), &addrlen) == SOCKET_ERROR) {
         return {SockAddrIn{}, GetAndLogLastError()};
     }
 
-    ASSERT(addrlen == sizeof(sockaddr_in));
+    return {TranslateToSockAddrIn(addr, addrlen), Errno::SUCCESS};
-    return {TranslateToSockAddrIn(addr), Errno::SUCCESS};
 }
 
 Errno Socket::Bind(SockAddrIn addr) {
@@ -519,7 +681,7 @@ Errno Socket::Shutdown(ShutdownHow how) {
     return GetAndLogLastError();
 }
 
-std::pair<s32, Errno> Socket::Recv(int flags, std::vector<u8>& message) {
+std::pair<s32, Errno> Socket::Recv(int flags, std::span<u8> message) {
     ASSERT(flags == 0);
     ASSERT(message.size() < static_cast<size_t>(std::numeric_limits<int>::max()));
 
@@ -532,21 +694,20 @@ std::pair<s32, Errno> Socket::Recv(int flags, std::vector<u8>& message) {
     return {-1, GetAndLogLastError()};
 }
 
-std::pair<s32, Errno> Socket::RecvFrom(int flags, std::vector<u8>& message, SockAddrIn* addr) {
+std::pair<s32, Errno> Socket::RecvFrom(int flags, std::span<u8> message, SockAddrIn* addr) {
     ASSERT(flags == 0);
     ASSERT(message.size() < static_cast<size_t>(std::numeric_limits<int>::max()));
 
-    sockaddr addr_in{};
+    sockaddr_in addr_in{};
     socklen_t addrlen = sizeof(addr_in);
     socklen_t* const p_addrlen = addr ? &addrlen : nullptr;
-    sockaddr* const p_addr_in = addr ? &addr_in : nullptr;
+    sockaddr* const p_addr_in = addr ? reinterpret_cast<sockaddr*>(&addr_in) : nullptr;
 
     const auto result = recvfrom(fd, reinterpret_cast<char*>(message.data()),
                                  static_cast<int>(message.size()), 0, p_addr_in, p_addrlen);
     if (result != SOCKET_ERROR) {
         if (addr) {
-            ASSERT(addrlen == sizeof(addr_in));
+            *addr = TranslateToSockAddrIn(addr_in, addrlen);
-            *addr = TranslateToSockAddrIn(addr_in);
         }
         return {static_cast<s32>(result), Errno::SUCCESS};
     }
@@ -597,6 +758,11 @@ Errno Socket::Close() {
     return Errno::SUCCESS;
 }
 
+std::pair<Errno, Errno> Socket::GetPendingError() {
+    auto [pending_err, getsockopt_err] = GetSockOpt<int>(fd, SO_ERROR);
+    return {TranslateNativeError(pending_err), getsockopt_err};
+}
+
 Errno Socket::SetLinger(bool enable, u32 linger) {
     return SetSockOpt(fd, SO_LINGER, MakeLinger(enable, linger));
 }

src/core/internal_network/network.h

@@ -16,6 +16,11 @@
 #include <netinet/in.h>
 #endif
 
+namespace Common {
+template <typename T, typename E>
+class Expected;
+}
+
 namespace Network {
 
 class SocketBase;
@@ -36,6 +41,26 @@ enum class Errno {
     NETUNREACH,
     TIMEDOUT,
     MSGSIZE,
+    INPROGRESS,
+    OTHER,
+};
+
+enum class GetAddrInfoError {
+    SUCCESS,
+    ADDRFAMILY,
+    AGAIN,
+    BADFLAGS,
+    FAIL,
+    FAMILY,
+    MEMORY,
+    NODATA,
+    NONAME,
+    SERVICE,
+    SOCKTYPE,
+    SYSTEM,
+    BADHINTS,
+    PROTOCOL,
+    OVERFLOW_,
     OTHER,
 };
 
@@ -49,6 +74,9 @@ enum class PollEvents : u16 {
     Err = 1 << 3,
     Hup = 1 << 4,
     Nval = 1 << 5,
+    RdNorm = 1 << 6,
+    RdBand = 1 << 7,
+    WrBand = 1 << 8,
 };
 
 DECLARE_ENUM_FLAG_OPERATORS(PollEvents);
@@ -82,4 +110,10 @@ constexpr IPv4Address TranslateIPv4(in_addr addr) {
 /// @return human ordered IPv4 address (e.g. 192.168.0.1) as an array
 std::optional<IPv4Address> GetHostIPv4Address();
 
+std::string IPv4AddressToString(IPv4Address ip_addr);
+u32 IPv4AddressToInteger(IPv4Address ip_addr);
+
+Common::Expected<std::vector<AddrInfo>, GetAddrInfoError> GetAddrInfo(
+    const std::string& host, const std::optional<std::string>& service);
+
 } // namespace Network

src/core/internal_network/socket_proxy.cpp

@@ -98,7 +98,7 @@ Errno ProxySocket::Shutdown(ShutdownHow how) {
     return Errno::SUCCESS;
 }
 
-std::pair<s32, Errno> ProxySocket::Recv(int flags, std::vector<u8>& message) {
+std::pair<s32, Errno> ProxySocket::Recv(int flags, std::span<u8> message) {
     LOG_WARNING(Network, "(STUBBED) called");
     ASSERT(flags == 0);
     ASSERT(message.size() < static_cast<size_t>(std::numeric_limits<int>::max()));
@@ -106,7 +106,7 @@ std::pair<s32, Errno> ProxySocket::Recv(int flags, std::vector<u8>& message) {
     return {static_cast<s32>(0), Errno::SUCCESS};
 }
 
-std::pair<s32, Errno> ProxySocket::RecvFrom(int flags, std::vector<u8>& message, SockAddrIn* addr) {
+std::pair<s32, Errno> ProxySocket::RecvFrom(int flags, std::span<u8> message, SockAddrIn* addr) {
     ASSERT(flags == 0);
     ASSERT(message.size() < static_cast<size_t>(std::numeric_limits<int>::max()));
 
@@ -140,8 +140,8 @@ std::pair<s32, Errno> ProxySocket::RecvFrom(int flags, std::vector<u8>& message,
     }
 }
 
-std::pair<s32, Errno> ProxySocket::ReceivePacket(int flags, std::vector<u8>& message,
+std::pair<s32, Errno> ProxySocket::ReceivePacket(int flags, std::span<u8> message, SockAddrIn* addr,
-                                                 SockAddrIn* addr, std::size_t max_length) {
+                                                 std::size_t max_length) {
     ProxyPacket& packet = received_packets.front();
     if (addr) {
         addr->family = Domain::INET;
@@ -153,10 +153,7 @@ std::pair<s32, Errno> ProxySocket::ReceivePacket(int flags, std::vector<u8>& mes
     std::size_t read_bytes;
     if (packet.data.size() > max_length) {
         read_bytes = max_length;
-        message.clear();
+        memcpy(message.data(), packet.data.data(), max_length);
-        std::copy(packet.data.begin(), packet.data.begin() + read_bytes,
-                  std::back_inserter(message));
-        message.resize(max_length);
 
         if (protocol == Protocol::UDP) {
             if (!peek) {
@@ -171,9 +168,7 @@ std::pair<s32, Errno> ProxySocket::ReceivePacket(int flags, std::vector<u8>& mes
         }
     } else {
         read_bytes = packet.data.size();
-        message.clear();
+        memcpy(message.data(), packet.data.data(), read_bytes);
-        std::copy(packet.data.begin(), packet.data.end(), std::back_inserter(message));
-        message.resize(max_length);
         if (!peek) {
             received_packets.pop();
         }
@@ -293,6 +288,11 @@ Errno ProxySocket::SetNonBlock(bool enable) {
     return Errno::SUCCESS;
 }
 
+std::pair<Errno, Errno> ProxySocket::GetPendingError() {
+    LOG_DEBUG(Network, "(STUBBED) called");
+    return {Errno::SUCCESS, Errno::SUCCESS};
+}
+
 bool ProxySocket::IsOpened() const {
     return fd != INVALID_SOCKET;
 }

src/core/internal_network/socket_proxy.h

@@ -39,11 +39,11 @@ public:
 
     Errno Shutdown(ShutdownHow how) override;
 
-    std::pair<s32, Errno> Recv(int flags, std::vector<u8>& message) override;
+    std::pair<s32, Errno> Recv(int flags, std::span<u8> message) override;
 
-    std::pair<s32, Errno> RecvFrom(int flags, std::vector<u8>& message, SockAddrIn* addr) override;
+    std::pair<s32, Errno> RecvFrom(int flags, std::span<u8> message, SockAddrIn* addr) override;
 
-    std::pair<s32, Errno> ReceivePacket(int flags, std::vector<u8>& message, SockAddrIn* addr,
+    std::pair<s32, Errno> ReceivePacket(int flags, std::span<u8> message, SockAddrIn* addr,
                                         std::size_t max_length);
 
     std::pair<s32, Errno> Send(std::span<const u8> message, int flags) override;
@@ -74,6 +74,8 @@ public:
     template <typename T>
     Errno SetSockOpt(SOCKET fd, int option, T value);
 
+    std::pair<Errno, Errno> GetPendingError() override;
+
     bool IsOpened() const override;
 
 private:

src/core/internal_network/sockets.h

@@ -59,10 +59,9 @@ public:
 
     virtual Errno Shutdown(ShutdownHow how) = 0;
 
-    virtual std::pair<s32, Errno> Recv(int flags, std::vector<u8>& message) = 0;
+    virtual std::pair<s32, Errno> Recv(int flags, std::span<u8> message) = 0;
 
-    virtual std::pair<s32, Errno> RecvFrom(int flags, std::vector<u8>& message,
+    virtual std::pair<s32, Errno> RecvFrom(int flags, std::span<u8> message, SockAddrIn* addr) = 0;
-                                           SockAddrIn* addr) = 0;
 
     virtual std::pair<s32, Errno> Send(std::span<const u8> message, int flags) = 0;
 
@@ -87,6 +86,8 @@ public:
 
     virtual Errno SetNonBlock(bool enable) = 0;
 
+    virtual std::pair<Errno, Errno> GetPendingError() = 0;
+
     virtual bool IsOpened() const = 0;
 
     virtual void HandleProxyPacket(const ProxyPacket& packet) = 0;
@@ -126,9 +127,9 @@ public:
 
     Errno Shutdown(ShutdownHow how) override;
 
-    std::pair<s32, Errno> Recv(int flags, std::vector<u8>& message) override;
+    std::pair<s32, Errno> Recv(int flags, std::span<u8> message) override;
 
-    std::pair<s32, Errno> RecvFrom(int flags, std::vector<u8>& message, SockAddrIn* addr) override;
+    std::pair<s32, Errno> RecvFrom(int flags, std::span<u8> message, SockAddrIn* addr) override;
 
     std::pair<s32, Errno> Send(std::span<const u8> message, int flags) override;
 
@@ -156,6 +157,11 @@ public:
     template <typename T>
     Errno SetSockOpt(SOCKET fd, int option, T value);
 
+    std::pair<Errno, Errno> GetPendingError() override;
+
+    template <typename T>
+    std::pair<T, Errno> GetSockOpt(SOCKET fd, int option);
+
     bool IsOpened() const override;
 
     void HandleProxyPacket(const ProxyPacket& packet) override;