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// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package agent
import (
"errors"
"io"
"net"
"sync"
"golang.org/x/crypto/ssh"
)
// RequestAgentForwarding sets up agent forwarding for the session.
// ForwardToAgent or ForwardToRemote should be called to route
// the authentication requests.
func RequestAgentForwarding(session *ssh.Session) error {
ok, err := session.SendRequest("auth-agent-req@openssh.com", true, nil)
if err != nil {
return err
}
if !ok {
return errors.New("forwarding request denied")
}
return nil
}
// ForwardToAgent routes authentication requests to the given keyring.
func ForwardToAgent(client *ssh.Client, keyring Agent) error {
channels := client.HandleChannelOpen(channelType)
if channels == nil {
return errors.New("agent: already have handler for " + channelType)
}
go func() {
for ch := range channels {
channel, reqs, err := ch.Accept()
if err != nil {
continue
}
go ssh.DiscardRequests(reqs)
go func() {
ServeAgent(keyring, channel)
channel.Close()
}()
}
}()
return nil
}
const channelType = "auth-agent@openssh.com"
// ForwardToRemote routes authentication requests to the ssh-agent
// process serving on the given unix socket.
func ForwardToRemote(client *ssh.Client, addr string) error {
channels := client.HandleChannelOpen(channelType)
if channels == nil {
return errors.New("agent: already have handler for " + channelType)
}
conn, err := net.Dial("unix", addr)
if err != nil {
return err
}
conn.Close()
go func() {
for ch := range channels {
channel, reqs, err := ch.Accept()
if err != nil {
continue
}
go ssh.DiscardRequests(reqs)
go forwardUnixSocket(channel, addr)
}
}()
return nil
}
func forwardUnixSocket(channel ssh.Channel, addr string) {
conn, err := net.Dial("unix", addr)
if err != nil {
return
}
var wg sync.WaitGroup
wg.Add(2)
go func() {
io.Copy(conn, channel)
conn.(*net.UnixConn).CloseWrite()
wg.Done()
}()
go func() {
io.Copy(channel, conn)
channel.CloseWrite()
wg.Done()
}()
wg.Wait()
conn.Close()
channel.Close()
}
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