Mercurial > dropbear

comparison svr-x11fwd.c @ 12:7a37cff27258

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
merge of a585c2284e9ad17bfe6c6fd8f18b1c5042b2df47 and e3f735bb16fbd5cfb6bcad70885550c1b79b874c
author Matt Johnston <matt@ucc.asn.au>
date Thu, 03 Jun 2004 17:29:17 +0000
parents 0f7d69d31b9d
children db2c8e6fb284
comparison
equal deleted inserted replaced
11:f76c9389e9e0 12:7a37cff27258
1 /*
2 * Dropbear - a SSH2 server
3 *
4 * Copyright (c) 2002,2003 Matt Johnston
5 * All rights reserved.
6 *
7 * Permission is hereby granted, free of charge, to any person obtaining a copy
8 * of this software and associated documentation files (the "Software"), to deal
9 * in the Software without restriction, including without limitation the rights
10 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
11 * copies of the Software, and to permit persons to whom the Software is
12 * furnished to do so, subject to the following conditions:
13 *
14 * The above copyright notice and this permission notice shall be included in
15 * all copies or substantial portions of the Software.
16 *
17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
18 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
20 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
21 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
22 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
23 * SOFTWARE. */
24
25 #include "includes.h"
26
27 #ifndef DISABLE_X11FWD
28 #include "x11fwd.h"
29 #include "session.h"
30 #include "ssh.h"
31 #include "dbutil.h"
32 #include "chansession.h"
33 #include "channel.h"
34 #include "packet.h"
35 #include "buffer.h"
36
37 #define X11BASEPORT 6000
38 #define X11BINDBASE 6010
39
40 static void x11accept(struct Listener* listener);
41 static int bindport(int fd);
42 static int send_msg_channel_open_x11(int fd, struct sockaddr_in* addr);
43
44 /* called as a request for a session channel, sets up listening X11 */
45 /* returns DROPBEAR_SUCCESS or DROPBEAR_FAILURE */
46 int x11req(struct ChanSess * chansess) {
47
48 int fd;
49
50 /* we already have an x11 connection */
51 if (chansess->x11listener != NULL) {
52 return DROPBEAR_FAILURE;
53 }
54
55 chansess->x11singleconn = buf_getbyte(ses.payload);
56 chansess->x11authprot = buf_getstring(ses.payload, NULL);
57 chansess->x11authcookie = buf_getstring(ses.payload, NULL);
58 chansess->x11screennum = buf_getint(ses.payload);
59
60 /* create listening socket */
61 fd = socket(PF_INET, SOCK_STREAM, 0);
62 if (fd < 0) {
63 goto fail;
64 }
65
66 /* allocate port and bind */
67 chansess->x11port = bindport(fd);
68 if (chansess->x11port < 0) {
69 goto fail;
70 }
71
72 /* listen */
73 if (listen(fd, 20) < 0) {
74 goto fail;
75 }
76
77 /* set non-blocking */
78 if (fcntl(fd, F_SETFL, O_NONBLOCK) < 0) {
79 goto fail;
80 }
81
82 /* listener code will handle the socket now.
83 * No cleanup handler needed, since listener_remove only happens
84 * from our cleanup anyway */
85 chansess->x11listener = new_listener( fd, 0, chansess, x11accept, NULL);
86 if (chansess->x11listener == NULL) {
87 goto fail;
88 }
89
90 return DROPBEAR_SUCCESS;
91
92 fail:
93 /* cleanup */
94 m_free(chansess->x11authprot);
95 m_free(chansess->x11authcookie);
96 close(fd);
97
98 return DROPBEAR_FAILURE;
99 }
100
101 /* accepts a new X11 socket */
102 /* returns DROPBEAR_FAILURE or DROPBEAR_SUCCESS */
103 static void x11accept(struct Listener* listener) {
104
105 int fd;
106 struct sockaddr_in addr;
107 int len;
108 int ret;
109
110 len = sizeof(addr);
111
112 fd = accept(listener->sock, (struct sockaddr*)&addr, &len);
113 if (fd < 0) {
114 return;
115 }
116
117 /* if single-connection we close it up */
118 if (((struct ChanSess *)(listener->typedata))->x11singleconn) {
119 x11cleanup(listener);
120 }
121
122 ret = send_msg_channel_open_x11(fd, &addr);
123 if (ret == DROPBEAR_FAILURE) {
124 close(fd);
125 }
126 }
127
128 /* This is called after switching to the user, and sets up the xauth
129 * and environment variables. */
130 void x11setauth(struct ChanSess *chansess) {
131
132 char display[20]; /* space for "localhost:12345.123" */
133 FILE * authprog;
134 int val;
135
136 if (chansess->x11listener == NULL) {
137 return;
138 }
139
140 /* create the DISPLAY string */
141 val = snprintf(display, sizeof(display), "localhost:%d.%d",
142 chansess->x11port - X11BASEPORT, chansess->x11screennum);
143 if (val < 0 || val >= (int)sizeof(display)) {
144 /* string was truncated */
145 return;
146 }
147
148 addnewvar("DISPLAY", display);
149
150 /* create the xauth string */
151 val = snprintf(display, sizeof(display), "unix:%d.%d",
152 chansess->x11port - X11BASEPORT, chansess->x11screennum);
153 if (val < 0 || val >= (int)sizeof(display)) {
154 /* string was truncated */
155 return;
156 }
157
158 /* popen is a nice function - code is strongly based on OpenSSH's */
159 authprog = popen(XAUTH_COMMAND, "w");
160 if (authprog) {
161 fprintf(authprog, "add %s %s %s\n",
162 display, chansess->x11authprot, chansess->x11authcookie);
163 pclose(authprog);
164 } else {
165 fprintf(stderr, "Failed to run %s\n", XAUTH_COMMAND);
166 }
167 }
168
169 void x11cleanup(struct Listener *listener) {
170
171 struct ChanSess *chansess = (struct ChanSess*)listener->typedata;
172
173 m_free(chansess->x11authprot);
174 m_free(chansess->x11authcookie);
175 remove_listener(listener);
176 chansess->x11listener = NULL;
177 }
178
179 static const struct ChanType chan_x11 = {
180 0, /* sepfds */
181 "x11",
182 NULL, /* inithandler */
183 NULL, /* checkclose */
184 NULL, /* reqhandler */
185 NULL /* closehandler */
186 };
187
188
189 static int send_msg_channel_open_x11(int fd, struct sockaddr_in* addr) {
190
191 char* ipstring;
192
193 if (send_msg_channel_open_init(fd, &chan_x11) == DROPBEAR_SUCCESS) {
194 ipstring = inet_ntoa(addr->sin_addr);
195 buf_putstring(ses.writepayload, ipstring, strlen(ipstring));
196 buf_putint(ses.writepayload, addr->sin_port);
197
198 encrypt_packet();
199 return DROPBEAR_SUCCESS;
200 } else {
201 return DROPBEAR_FAILURE;
202 }
203
204 }
205
206 /* returns the port bound to, or -1 on failure.
207 * Will attempt to bind to a port X11BINDBASE (6010 usually) or upwards */
208 static int bindport(int fd) {
209
210 struct sockaddr_in addr;
211 uint16_t port;
212
213 memset((void*)&addr, 0x0, sizeof(addr));
214 addr.sin_family = AF_INET;
215 addr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
216
217 /* if we can't find one in 2000 ports free, something's wrong */
218 for (port = X11BINDBASE; port < X11BINDBASE + 2000; port++) {
219 addr.sin_port = htons(port);
220 if (bind(fd, (struct sockaddr*)&addr,
221 sizeof(struct sockaddr_in)) == 0) {
222 /* success */
223 return port;
224 }
225 if (errno == EADDRINUSE) {
226 /* try the next port */
227 continue;
228 }
229 /* otherwise it was an error we don't know about */
230 dropbear_log(LOG_DEBUG, "failed to bind x11 socket");
231 break;
232 }
233 return -1;
234 }
235 #endif /* DROPBEAR_X11FWD */