mirror of https://github.com/docker/cli.git
73 lines
1.8 KiB
Go
73 lines
1.8 KiB
Go
package socket
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import (
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"errors"
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"io"
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"net"
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"os"
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"github.com/docker/distribution/uuid"
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)
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// EnvKey represents the well-known environment variable used to pass the plugin being
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// executed the socket name it should listen on to coordinate with the host CLI.
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const EnvKey = "DOCKER_CLI_PLUGIN_SOCKET"
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// SetupConn sets up a Unix socket listener, establishes a goroutine to handle connections
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// and update the conn pointer, and returns the environment variable to pass to the plugin.
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func SetupConn(conn **net.UnixConn) (string, error) {
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listener, err := listen("docker_cli_" + uuid.Generate().String())
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if err != nil {
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return "", err
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}
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accept(listener, conn)
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return EnvKey + "=" + listener.Addr().String(), nil
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}
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func accept(listener *net.UnixListener, conn **net.UnixConn) {
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defer listener.Close()
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go func() {
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for {
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// ignore error here, if we failed to accept a connection,
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// conn is nil and we fallback to previous behavior
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*conn, _ = listener.AcceptUnix()
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// perform any platform-specific actions on accept (e.g. unlink non-abstract sockets)
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onAccept(*conn, listener)
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}
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}()
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}
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// ConnectAndWait connects to the socket passed via well-known env var,
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// if present, and attempts to read from it until it receives an EOF, at which
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// point cb is called.
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func ConnectAndWait(cb func()) {
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socketAddr, ok := os.LookupEnv(EnvKey)
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if !ok {
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// if a plugin compiled against a more recent version of docker/cli
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// is executed by an older CLI binary, ignore missing environment
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// variable and behave as usual
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return
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}
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addr, err := net.ResolveUnixAddr("unix", socketAddr)
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if err != nil {
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return
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}
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conn, err := net.DialUnix("unix", nil, addr)
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if err != nil {
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return
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}
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go func() {
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b := make([]byte, 1)
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for {
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_, err := conn.Read(b)
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if errors.Is(err, io.EOF) {
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cb()
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}
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}
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}()
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}
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