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Support for local port forwarding (gliderlabs#38)
* Support local port forwarding * refactor testSession to return ssh client as well * Tests for local port forwarding
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,58 @@ | ||
| package ssh | ||
|
|
||
| import ( | ||
| "fmt" | ||
| "io" | ||
| "net" | ||
|
|
||
| gossh "golang.org/x/crypto/ssh" | ||
| ) | ||
|
|
||
| // direct-tcpip data struct as specified in RFC4254, Section 7.2 | ||
| type forwardData struct { | ||
| DestinationHost string | ||
| DestinationPort uint32 | ||
|
|
||
| OriginatorHost string | ||
| OriginatorPort uint32 | ||
| } | ||
|
|
||
| func directTcpipHandler(srv *Server, conn *gossh.ServerConn, newChan gossh.NewChannel, ctx *sshContext) { | ||
| d := forwardData{} | ||
| if err := gossh.Unmarshal(newChan.ExtraData(), &d); err != nil { | ||
| newChan.Reject(gossh.ConnectionFailed, "error parsing forward data: "+err.Error()) | ||
| return | ||
| } | ||
|
|
||
| if srv.LocalPortForwardingCallback == nil || !srv.LocalPortForwardingCallback(ctx, d.DestinationHost, d.DestinationPort) { | ||
| newChan.Reject(gossh.Prohibited, "port forwarding is disabled") | ||
| return | ||
| } | ||
|
|
||
| dest := fmt.Sprintf("%s:%d", d.DestinationHost, d.DestinationPort) | ||
|
|
||
| var dialer net.Dialer | ||
| dconn, err := dialer.DialContext(ctx, "tcp", dest) | ||
| if err != nil { | ||
| newChan.Reject(gossh.ConnectionFailed, err.Error()) | ||
| return | ||
| } | ||
|
|
||
| ch, reqs, err := newChan.Accept() | ||
| if err != nil { | ||
| dconn.Close() | ||
| return | ||
| } | ||
| go gossh.DiscardRequests(reqs) | ||
|
|
||
| go func() { | ||
| defer ch.Close() | ||
| defer dconn.Close() | ||
| io.Copy(ch, dconn) | ||
| }() | ||
| go func() { | ||
| defer ch.Close() | ||
| defer dconn.Close() | ||
| io.Copy(dconn, ch) | ||
| }() | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,83 @@ | ||
| package ssh | ||
|
|
||
| import ( | ||
| "bytes" | ||
| "fmt" | ||
| "io/ioutil" | ||
| "net" | ||
| "strings" | ||
| "testing" | ||
|
|
||
| gossh "golang.org/x/crypto/ssh" | ||
| ) | ||
|
|
||
| var sampleServerResponse = []byte("Hello world") | ||
|
|
||
| func sampleSocketServer() net.Listener { | ||
| l := newLocalListener() | ||
|
|
||
| go func() { | ||
| conn, err := l.Accept() | ||
| if err != nil { | ||
| return | ||
| } | ||
| conn.Write(sampleServerResponse) | ||
| conn.Close() | ||
| }() | ||
|
|
||
| return l | ||
| } | ||
|
|
||
| func newTestSessionWithForwarding(t *testing.T, forwardingEnabled bool) (net.Listener, *gossh.Client, func()) { | ||
| l := sampleSocketServer() | ||
|
|
||
| _, client, cleanup := newTestSession(t, &Server{ | ||
| Handler: func(s Session) {}, | ||
| LocalPortForwardingCallback: func(ctx Context, destinationHost string, destinationPort uint32) bool { | ||
| addr := fmt.Sprintf("%s:%d", destinationHost, destinationPort) | ||
| if addr != l.Addr().String() { | ||
| panic("unexpected destinationHost: " + addr) | ||
| } | ||
| return forwardingEnabled | ||
| }, | ||
| }, nil) | ||
|
|
||
| return l, client, func() { | ||
| cleanup() | ||
| l.Close() | ||
| } | ||
| } | ||
|
|
||
| func TestLocalPortForwardingWorks(t *testing.T) { | ||
| t.Parallel() | ||
|
|
||
| l, client, cleanup := newTestSessionWithForwarding(t, true) | ||
| defer cleanup() | ||
|
|
||
| conn, err := client.Dial("tcp", l.Addr().String()) | ||
| if err != nil { | ||
| t.Fatalf("Error connecting to %v: %v", l.Addr().String(), err) | ||
| } | ||
| result, err := ioutil.ReadAll(conn) | ||
| if err != nil { | ||
| t.Fatal(err) | ||
| } | ||
| if !bytes.Equal(result, sampleServerResponse) { | ||
| t.Fatalf("result = %#v; want %#v", result, sampleServerResponse) | ||
| } | ||
| } | ||
|
|
||
| func TestLocalPortForwardingRespectsCallback(t *testing.T) { | ||
| t.Parallel() | ||
|
|
||
| l, client, cleanup := newTestSessionWithForwarding(t, false) | ||
| defer cleanup() | ||
|
|
||
| _, err := client.Dial("tcp", l.Addr().String()) | ||
| if err == nil { | ||
| t.Fatalf("Expected error connecting to %v but it succeeded", l.Addr().String()) | ||
| } | ||
| if !strings.Contains(err.Error(), "port forwarding is disabled") { | ||
| t.Fatalf("Expected permission error but got %#v", err) | ||
| } | ||
| } |