1051a0d154
* agent: added agent forwarding support with an example * context: encode session id to hex string * agent: ensure conn doesn't change in closure as loop iterates * tests: use HostKeyCallback in ClientConfig * README: noting examples in _example * agent: documented exported names, added constants for temp file creation Signed-off-by: Jeff Lindsay <progrium@gmail.com>
82 lines
1.9 KiB
Go
82 lines
1.9 KiB
Go
package ssh
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import (
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"io"
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"io/ioutil"
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"net"
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"path"
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"sync"
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gossh "golang.org/x/crypto/ssh"
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)
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const (
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agentRequestType = "auth-agent-req@openssh.com"
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agentChannelType = "auth-agent@openssh.com"
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agentTempDir = "auth-agent"
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agentListenFile = "listener.sock"
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)
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// contextKeyAgentRequest is an internal context key for storing if the
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// client requested agent forwarding
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var contextKeyAgentRequest = &contextKey{"auth-agent-req"}
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func setAgentRequested(sess *session) {
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sess.ctx.SetValue(contextKeyAgentRequest, true)
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}
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// AgentRequested returns true if the client requested agent forwarding.
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func AgentRequested(sess Session) bool {
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return sess.Context().Value(contextKeyAgentRequest) == true
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}
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// NewAgentListener sets up a temporary Unix socket that can be communicated
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// to the session environment and used for forwarding connections.
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func NewAgentListener() (net.Listener, error) {
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dir, err := ioutil.TempDir("", agentTempDir)
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if err != nil {
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return nil, err
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}
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l, err := net.Listen("unix", path.Join(dir, agentListenFile))
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if err != nil {
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return nil, err
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}
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return l, nil
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}
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// ForwardAgentConnections takes connections from a listener to proxy into the
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// session on the OpenSSH channel for agent connections. It blocks and services
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// connections until the listener stop accepting.
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func ForwardAgentConnections(l net.Listener, s Session) {
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sshConn := s.Context().Value(ContextKeyConn).(gossh.Conn)
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for {
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conn, err := l.Accept()
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if err != nil {
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return
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}
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go func(conn net.Conn) {
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defer conn.Close()
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channel, reqs, err := sshConn.OpenChannel(agentChannelType, nil)
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if err != nil {
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return
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}
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defer channel.Close()
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go gossh.DiscardRequests(reqs)
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var wg sync.WaitGroup
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wg.Add(2)
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go func() {
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io.Copy(conn, channel)
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conn.(*net.UnixConn).CloseWrite()
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wg.Done()
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}()
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go func() {
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io.Copy(channel, conn)
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channel.CloseWrite()
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wg.Done()
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}()
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wg.Wait()
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}(conn)
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}
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}
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