1// Copyright 2013 The Go Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4
5package ssh
6
7import (
8	"fmt"
9	"net"
10)
11
12// OpenChannelError is returned if the other side rejects an
13// OpenChannel request.
14type OpenChannelError struct {
15	Reason  RejectionReason
16	Message string
17}
18
19func (e *OpenChannelError) Error() string {
20	return fmt.Sprintf("ssh: rejected: %s (%s)", e.Reason, e.Message)
21}
22
23// ConnMetadata holds metadata for the connection.
24type ConnMetadata interface {
25	// User returns the user ID for this connection.
26	User() string
27
28	// SessionID returns the session hash, also denoted by H.
29	SessionID() []byte
30
31	// ClientVersion returns the client's version string as hashed
32	// into the session ID.
33	ClientVersion() []byte
34
35	// ServerVersion returns the server's version string as hashed
36	// into the session ID.
37	ServerVersion() []byte
38
39	// RemoteAddr returns the remote address for this connection.
40	RemoteAddr() net.Addr
41
42	// LocalAddr returns the local address for this connection.
43	LocalAddr() net.Addr
44}
45
46// Conn represents an SSH connection for both server and client roles.
47// Conn is the basis for implementing an application layer, such
48// as ClientConn, which implements the traditional shell access for
49// clients.
50type Conn interface {
51	ConnMetadata
52
53	// SendRequest sends a global request, and returns the
54	// reply. If wantReply is true, it returns the response status
55	// and payload. See also RFC4254, section 4.
56	SendRequest(name string, wantReply bool, payload []byte) (bool, []byte, error)
57
58	// OpenChannel tries to open an channel. If the request is
59	// rejected, it returns *OpenChannelError. On success it returns
60	// the SSH Channel and a Go channel for incoming, out-of-band
61	// requests. The Go channel must be serviced, or the
62	// connection will hang.
63	OpenChannel(name string, data []byte) (Channel, <-chan *Request, error)
64
65	// Close closes the underlying network connection
66	Close() error
67
68	// Wait blocks until the connection has shut down, and returns the
69	// error causing the shutdown.
70	Wait() error
71
72	// TODO(hanwen): consider exposing:
73	//   RequestKeyChange
74	//   Disconnect
75}
76
77// DiscardRequests consumes and rejects all requests from the
78// passed-in channel.
79func DiscardRequests(in <-chan *Request) {
80	for req := range in {
81		if req.WantReply {
82			req.Reply(false, nil)
83		}
84	}
85}
86
87// A connection represents an incoming connection.
88type connection struct {
89	transport *handshakeTransport
90	sshConn
91
92	// The connection protocol.
93	*mux
94}
95
96func (c *connection) Close() error {
97	return c.sshConn.conn.Close()
98}
99
100// sshconn provides net.Conn metadata, but disallows direct reads and
101// writes.
102type sshConn struct {
103	conn net.Conn
104
105	user          string
106	sessionID     []byte
107	clientVersion []byte
108	serverVersion []byte
109}
110
111func dup(src []byte) []byte {
112	dst := make([]byte, len(src))
113	copy(dst, src)
114	return dst
115}
116
117func (c *sshConn) User() string {
118	return c.user
119}
120
121func (c *sshConn) RemoteAddr() net.Addr {
122	return c.conn.RemoteAddr()
123}
124
125func (c *sshConn) Close() error {
126	return c.conn.Close()
127}
128
129func (c *sshConn) LocalAddr() net.Addr {
130	return c.conn.LocalAddr()
131}
132
133func (c *sshConn) SessionID() []byte {
134	return dup(c.sessionID)
135}
136
137func (c *sshConn) ClientVersion() []byte {
138	return dup(c.clientVersion)
139}
140
141func (c *sshConn) ServerVersion() []byte {
142	return dup(c.serverVersion)
143}
144