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comparison x11fwd.c @ 4:fe6bca95afa7

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Makefile.in contains updated files required
author Matt Johnston <matt@ucc.asn.au>
date Tue, 01 Jun 2004 02:46:09 +0000
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children 7f77962de998
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-1:000000000000 4:fe6bca95afa7
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 int bindport(int fd);
41 static int send_msg_channel_open_x11(int fd, struct sockaddr_in* addr);
42
43 /* called as a request for a session channel, sets up listening X11 */
44 /* returns DROPBEAR_SUCCESS or DROPBEAR_FAILURE */
45 int x11req(struct ChanSess * chansess) {
46
47 /* we already have an x11 connection */
48 if (chansess->x11fd != -1) {
49 return DROPBEAR_FAILURE;
50 }
51
52 chansess->x11singleconn = buf_getbyte(ses.payload);
53 chansess->x11authprot = buf_getstring(ses.payload, NULL);
54 chansess->x11authcookie = buf_getstring(ses.payload, NULL);
55 chansess->x11screennum = buf_getint(ses.payload);
56
57 /* create listening socket */
58 chansess->x11fd = socket(PF_INET, SOCK_STREAM, 0);
59 if (chansess->x11fd < 0) {
60 goto fail;
61 }
62
63 /* allocate port and bind */
64 chansess->x11port = bindport(chansess->x11fd);
65 if (chansess->x11port < 0) {
66 goto fail;
67 }
68
69 /* listen */
70 if (listen(chansess->x11fd, 20) < 0) {
71 goto fail;
72 }
73
74 /* set non-blocking */
75 if (fcntl(chansess->x11fd, F_SETFL, O_NONBLOCK) < 0) {
76 goto fail;
77 }
78
79 /* channel.c's channel fd code will handle the socket now */
80
81 /* set the maxfd so that select() loop will notice it */
82 ses.maxfd = MAX(ses.maxfd, chansess->x11fd);
83
84 return DROPBEAR_SUCCESS;
85
86 fail:
87 /* cleanup */
88 x11cleanup(chansess);
89
90 return DROPBEAR_FAILURE;
91 }
92
93 /* accepts a new X11 socket */
94 /* returns DROPBEAR_FAILURE or DROPBEAR_SUCCESS */
95 int x11accept(struct ChanSess * chansess) {
96
97 int fd;
98 struct sockaddr_in addr;
99 int len;
100
101 len = sizeof(addr);
102
103 fd = accept(chansess->x11fd, (struct sockaddr*)&addr, &len);
104 if (fd < 0) {
105 return DROPBEAR_FAILURE;
106 }
107
108 /* if single-connection we close it up */
109 if (chansess->x11singleconn) {
110 x11cleanup(chansess);
111 }
112
113 return send_msg_channel_open_x11(fd, &addr);
114 }
115
116 /* This is called after switching to the user, and sets up the xauth
117 * and environment variables. */
118 void x11setauth(struct ChanSess *chansess) {
119
120 char display[20]; /* space for "localhost:12345.123" */
121 FILE * authprog;
122 int val;
123
124 if (chansess->x11fd == -1) {
125 return;
126 }
127
128 /* create the DISPLAY string */
129 val = snprintf(display, sizeof(display), "localhost:%d.%d",
130 chansess->x11port - X11BASEPORT, chansess->x11screennum);
131 if (val < 0 || val >= (int)sizeof(display)) {
132 /* string was truncated */
133 return;
134 }
135
136 addnewvar("DISPLAY", display);
137
138 /* create the xauth string */
139 val = snprintf(display, sizeof(display), "unix:%d.%d",
140 chansess->x11port - X11BASEPORT, chansess->x11screennum);
141 if (val < 0 || val >= (int)sizeof(display)) {
142 /* string was truncated */
143 return;
144 }
145
146 /* popen is a nice function - code is strongly based on OpenSSH's */
147 authprog = popen(XAUTH_COMMAND, "w");
148 if (authprog) {
149 fprintf(authprog, "add %s %s %s\n",
150 display, chansess->x11authprot, chansess->x11authcookie);
151 pclose(authprog);
152 } else {
153 fprintf(stderr, "Failed to run %s\n", XAUTH_COMMAND);
154 }
155 }
156
157 void x11cleanup(struct ChanSess * chansess) {
158
159 if (chansess->x11fd == -1) {
160 return;
161 }
162
163 m_free(chansess->x11authprot);
164 m_free(chansess->x11authcookie);
165 close(chansess->x11fd);
166 chansess->x11fd = -1;
167 }
168
169 static int send_msg_channel_open_x11(int fd, struct sockaddr_in* addr) {
170
171 char* ipstring;
172
173 if (send_msg_channel_open_init(fd, CHANNEL_ID_X11, "x11")
174 == DROPBEAR_SUCCESS) {
175 ipstring = inet_ntoa(addr->sin_addr);
176 buf_putstring(ses.writepayload, ipstring, strlen(ipstring));
177 buf_putint(ses.writepayload, addr->sin_port);
178
179 encrypt_packet();
180 return DROPBEAR_SUCCESS;
181 } else {
182 return DROPBEAR_FAILURE;
183 }
184
185 }
186
187 /* returns the port bound to, or -1 on failure.
188 * Will attempt to bind to a port X11BINDBASE (6010 usually) or upwards */
189 static int bindport(int fd) {
190
191 struct sockaddr_in addr;
192 uint16_t port;
193
194 memset((void*)&addr, 0x0, sizeof(addr));
195 addr.sin_family = AF_INET;
196 addr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
197
198 /* if we can't find one in 2000 ports free, something's wrong */
199 for (port = X11BINDBASE; port < X11BINDBASE + 2000; port++) {
200 addr.sin_port = htons(port);
201 if (bind(fd, (struct sockaddr*)&addr,
202 sizeof(struct sockaddr_in)) == 0) {
203 /* success */
204 return port;
205 }
206 if (errno == EADDRINUSE) {
207 /* try the next port */
208 continue;
209 }
210 /* otherwise it was an error we don't know about */
211 dropbear_log(LOG_DEBUG, "failed to bind x11 socket");
212 break;
213 }
214 return -1;
215 }
216 #endif /* DROPBEAR_X11FWD */