1 /*
2  * rfcomm_pppd.c
3  */
4 
5 /*-
6  * SPDX-License-Identifier: BSD-2-Clause
7  *
8  * Copyright (c) 2001-2008 Maksim Yevmenkin <m_evmenkin@yahoo.com>
9  * All rights reserved.
10  *
11  * Redistribution and use in source and binary forms, with or without
12  * modification, are permitted provided that the following conditions
13  * are met:
14  * 1. Redistributions of source code must retain the above copyright
15  *    notice, this list of conditions and the following disclaimer.
16  * 2. Redistributions in binary form must reproduce the above copyright
17  *    notice, this list of conditions and the following disclaimer in the
18  *    documentation and/or other materials provided with the distribution.
19  *
20  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23  * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30  * SUCH DAMAGE.
31  *
32  * $Id: rfcomm_pppd.c,v 1.5 2003/09/07 18:32:11 max Exp $
33  */
34 #define L2CAP_SOCKET_CHECKED
35 #include <bluetooth.h>
36 #include <ctype.h>
37 #include <err.h>
38 #include <errno.h>
39 #include <fcntl.h>
40 #include <sdp.h>
41 #include <signal.h>
42 #include <stdarg.h>
43 #include <stdio.h>
44 #include <stdlib.h>
45 #include <string.h>
46 #include <syslog.h>
47 #include <unistd.h>
48 
49 #define RFCOMM_PPPD	"rfcomm_pppd"
50 
51 int		rfcomm_channel_lookup	(bdaddr_t const *local,
52 					 bdaddr_t const *remote,
53 					 int service, int *channel, int *error);
54 
55 static void	exec_ppp	(int s, char *unit, char *label);
56 static void	sighandler	(int s);
57 static void	usage		(void);
58 
59 static int	done;
60 
61 /* Main */
62 int
63 main(int argc, char *argv[])
64 {
65 	struct sockaddr_rfcomm   sock_addr;
66 	char			*label = NULL, *unit = NULL, *ep = NULL;
67 	bdaddr_t		 addr;
68 	int			 s, channel, detach, server, service,
69 				 regdun, regsp;
70 	pid_t			 pid;
71 
72 	memcpy(&addr, NG_HCI_BDADDR_ANY, sizeof(addr));
73 	channel = 0;
74 	detach = 1;
75 	server = 0;
76 	service = 0;
77 	regdun = 0;
78 	regsp = 0;
79 
80 	/* Parse command line arguments */
81 	while ((s = getopt(argc, argv, "a:cC:dDhl:sSu:")) != -1) {
82 		switch (s) {
83 		case 'a': /* BDADDR */
84 			if (!bt_aton(optarg, &addr)) {
85 				struct hostent	*he = NULL;
86 
87 				if ((he = bt_gethostbyname(optarg)) == NULL)
88 					errx(1, "%s: %s", optarg, hstrerror(h_errno));
89 
90 				memcpy(&addr, he->h_addr, sizeof(addr));
91 			}
92 			break;
93 
94 		case 'c': /* client */
95 			server = 0;
96 			break;
97 
98 		case 'C': /* RFCOMM channel */
99 			channel = strtoul(optarg, &ep, 10);
100 			if (*ep != '\0') {
101 				channel = 0;
102 				switch (tolower(optarg[0])) {
103 				case 'd': /* DialUp Networking */
104 					service = SDP_SERVICE_CLASS_DIALUP_NETWORKING;
105 					break;
106 
107 				case 'l': /* LAN Access Using PPP */
108 					service = SDP_SERVICE_CLASS_LAN_ACCESS_USING_PPP;
109 					break;
110 				}
111 			}
112 			break;
113 
114 		case 'd': /* do not detach */
115 			detach = 0;
116 			break;
117 
118 		case 'D': /* Register DUN service as well as LAN service */
119 			regdun = 1;
120 			break;
121 
122 		case 'l': /* PPP label */
123 			label = optarg;
124 			break;
125 
126 		case 's': /* server */
127 			server = 1;
128 			break;
129 
130 		case 'S': /* Register SP service as well as LAN service */
131 			regsp = 1;
132 			break;
133 
134 		case 'u': /* PPP -unit option */
135 			strtoul(optarg, &ep, 10);
136 			if (*ep != '\0')
137 				usage();
138 				/* NOT REACHED */
139 
140 			unit = optarg;
141 			break;
142 
143 		case 'h':
144 		default:
145 			usage();
146 			/* NOT REACHED */
147 		}
148 	}
149 
150 	/* Check if we got everything we wanted */
151 	if (label == NULL)
152                 errx(1, "Must specify PPP label");
153 
154 	if (!server) {
155 		if (memcmp(&addr, NG_HCI_BDADDR_ANY, sizeof(addr)) == 0)
156                 	errx(1, "Must specify server BD_ADDR");
157 
158 		/* Check channel, if was not set then obtain it via SDP */
159 		if (channel == 0 && service != 0)
160 			if (rfcomm_channel_lookup(NULL, &addr, service,
161 							&channel, &s) != 0)
162 				errc(1, s, "Could not obtain RFCOMM channel");
163 	}
164 
165         if (channel <= 0 || channel > 30)
166                 errx(1, "Invalid RFCOMM channel number %d", channel);
167 
168 	openlog(RFCOMM_PPPD, LOG_PID | LOG_PERROR | LOG_NDELAY, LOG_USER);
169 
170 	if (detach && daemon(0, 0) < 0) {
171 		syslog(LOG_ERR, "Could not daemon(0, 0). %s (%d)",
172 			strerror(errno), errno);
173 		exit(1);
174 	}
175 
176 	s = socket(PF_BLUETOOTH, SOCK_STREAM, BLUETOOTH_PROTO_RFCOMM);
177 	if (s < 0) {
178 		syslog(LOG_ERR, "Could not create socket. %s (%d)",
179 			strerror(errno), errno);
180 		exit(1);
181 	}
182 
183 	if (server) {
184 		struct sigaction	 sa;
185 		void			*ss = NULL;
186 		sdp_lan_profile_t	 lan;
187 
188 		/* Install signal handler */
189 		memset(&sa, 0, sizeof(sa));
190 		sa.sa_handler = sighandler;
191 
192 		if (sigaction(SIGTERM, &sa, NULL) < 0) {
193 			syslog(LOG_ERR, "Could not sigaction(SIGTERM). %s (%d)",
194 				strerror(errno), errno);
195 			exit(1);
196 		}
197 
198 		if (sigaction(SIGHUP, &sa, NULL) < 0) {
199 			syslog(LOG_ERR, "Could not sigaction(SIGHUP). %s (%d)",
200 				strerror(errno), errno);
201 			exit(1);
202 		}
203 
204 		if (sigaction(SIGINT, &sa, NULL) < 0) {
205 			syslog(LOG_ERR, "Could not sigaction(SIGINT). %s (%d)",
206 				strerror(errno), errno);
207 			exit(1);
208 		}
209 
210 		sa.sa_handler = SIG_IGN;
211 		sa.sa_flags = SA_NOCLDWAIT;
212 
213 		if (sigaction(SIGCHLD, &sa, NULL) < 0) {
214 			syslog(LOG_ERR, "Could not sigaction(SIGCHLD). %s (%d)",
215 				strerror(errno), errno);
216 			exit(1);
217 		}
218 
219 		/* bind socket and listen for incoming connections */
220 		sock_addr.rfcomm_len = sizeof(sock_addr);
221 		sock_addr.rfcomm_family = AF_BLUETOOTH;
222 		memcpy(&sock_addr.rfcomm_bdaddr, &addr,
223 			sizeof(sock_addr.rfcomm_bdaddr));
224 		sock_addr.rfcomm_channel = channel;
225 
226 		if (bind(s, (struct sockaddr *) &sock_addr,
227 				sizeof(sock_addr)) < 0) {
228 			syslog(LOG_ERR, "Could not bind socket. %s (%d)",
229 				strerror(errno), errno);
230 			exit(1);
231 		}
232 
233 		if (listen(s, 10) < 0) {
234 			syslog(LOG_ERR, "Could not listen on socket. %s (%d)",
235 				strerror(errno), errno);
236 			exit(1);
237 		}
238 
239 		ss = sdp_open_local(NULL);
240 		if (ss == NULL) {
241 			syslog(LOG_ERR, "Unable to create local SDP session");
242 			exit(1);
243 		}
244 
245 		if (sdp_error(ss) != 0) {
246 			syslog(LOG_ERR, "Unable to open local SDP session. " \
247 				"%s (%d)", strerror(sdp_error(ss)),
248 				sdp_error(ss));
249 			exit(1);
250 		}
251 
252 		memset(&lan, 0, sizeof(lan));
253 		lan.server_channel = channel;
254 
255 		if (sdp_register_service(ss,
256 				SDP_SERVICE_CLASS_LAN_ACCESS_USING_PPP,
257 				&addr, (void *) &lan, sizeof(lan), NULL) != 0) {
258 			syslog(LOG_ERR, "Unable to register LAN service with " \
259 				"local SDP daemon. %s (%d)",
260 				strerror(sdp_error(ss)), sdp_error(ss));
261 			exit(1);
262 		}
263 
264 		/*
265 		 * Register DUN (Dial-Up Networking) service on the same
266 		 * RFCOMM channel if requested. There is really no good reason
267 		 * to not to support this. AT-command exchange can be faked
268 		 * with chat script in ppp.conf
269 		 */
270 
271 		if (regdun) {
272 			sdp_dun_profile_t	dun;
273 
274 			memset(&dun, 0, sizeof(dun));
275 			dun.server_channel = channel;
276 
277 			if (sdp_register_service(ss,
278 					SDP_SERVICE_CLASS_DIALUP_NETWORKING,
279 					&addr, (void *) &dun, sizeof(dun),
280 					NULL) != 0) {
281 				syslog(LOG_ERR, "Unable to register DUN " \
282 					"service with local SDP daemon. " \
283 					"%s (%d)", strerror(sdp_error(ss)),
284 					sdp_error(ss));
285 				exit(1);
286 			}
287 		}
288 
289 		/*
290 		 * Register SP (Serial Port) service on the same RFCOMM channel
291 		 * if requested. It appears that some cell phones are using so
292 		 * called "callback mechanism". In this scenario user is trying
293 		 * to connect his cell phone to the Internet, and, user's host
294 		 * computer is acting as the gateway server. It seems that it
295 		 * is not possible to tell the phone to just connect and start
296 		 * using the LAN service. Instead the user's host computer must
297 		 * "jump start" the phone by connecting to the phone's SP
298 		 * service. What happens next is the phone kills the existing
299 		 * connection and opens another connection back to the user's
300 		 * host computer. The phone really wants to use LAN service,
301 		 * but for whatever reason it looks for SP service on the
302 		 * user's host computer. This brain damaged behavior was
303 		 * reported for Nokia 6600 and Sony/Ericsson P900. Both phones
304 		 * are Symbian-based phones. Perhaps this is a Symbian problem?
305 		 */
306 
307 		if (regsp) {
308 			sdp_sp_profile_t	sp;
309 
310 			memset(&sp, 0, sizeof(sp));
311 			sp.server_channel = channel;
312 
313 			if (sdp_register_service(ss,
314 					SDP_SERVICE_CLASS_SERIAL_PORT,
315 					&addr, (void *) &sp, sizeof(sp),
316 					NULL) != 0) {
317 				syslog(LOG_ERR, "Unable to register SP " \
318 					"service with local SDP daemon. " \
319 					"%s (%d)", strerror(sdp_error(ss)),
320 					sdp_error(ss));
321 				exit(1);
322 			}
323 		}
324 
325 		for (done = 0; !done; ) {
326 			socklen_t	len = sizeof(sock_addr);
327 			int		s1 = accept(s, (struct sockaddr *) &sock_addr, &len);
328 
329 			if (s1 < 0) {
330 				syslog(LOG_ERR, "Could not accept connection " \
331 					"on socket. %s (%d)", strerror(errno),
332 					errno);
333 				exit(1);
334 			}
335 
336 			pid = fork();
337 			if (pid == (pid_t) -1) {
338 				syslog(LOG_ERR, "Could not fork(). %s (%d)",
339 					strerror(errno), errno);
340 				exit(1);
341 			}
342 
343 			if (pid == 0) {
344 				sdp_close(ss);
345 				close(s);
346 
347 				/* Reset signal handler */
348 				memset(&sa, 0, sizeof(sa));
349 				sa.sa_handler = SIG_DFL;
350 
351 				sigaction(SIGTERM, &sa, NULL);
352 				sigaction(SIGHUP, &sa, NULL);
353 				sigaction(SIGINT, &sa, NULL);
354 				sigaction(SIGCHLD, &sa, NULL);
355 
356 				/* Become daemon */
357 				daemon(0, 0);
358 
359 				/*
360 				 * XXX Make sure user does not shoot himself
361 				 * in the foot. Do not pass unit option to the
362 				 * PPP when operating in the server mode.
363 				 */
364 
365 				exec_ppp(s1, NULL, label);
366 			} else
367 				close(s1);
368 		}
369 	} else {
370 		sock_addr.rfcomm_len = sizeof(sock_addr);
371 		sock_addr.rfcomm_family = AF_BLUETOOTH;
372 		memcpy(&sock_addr.rfcomm_bdaddr, NG_HCI_BDADDR_ANY,
373 			sizeof(sock_addr.rfcomm_bdaddr));
374 		sock_addr.rfcomm_channel = 0;
375 
376 		if (bind(s, (struct sockaddr *) &sock_addr,
377 				sizeof(sock_addr)) < 0) {
378 			syslog(LOG_ERR, "Could not bind socket. %s (%d)",
379 				strerror(errno), errno);
380 			exit(1);
381 		}
382 
383 		memcpy(&sock_addr.rfcomm_bdaddr, &addr,
384 			sizeof(sock_addr.rfcomm_bdaddr));
385 		sock_addr.rfcomm_channel = channel;
386 
387 		if (connect(s, (struct sockaddr *) &sock_addr,
388 				sizeof(sock_addr)) < 0) {
389 			syslog(LOG_ERR, "Could not connect socket. %s (%d)",
390 				strerror(errno), errno);
391 			exit(1);
392 		}
393 
394 		exec_ppp(s, unit, label);
395 	}
396 
397 	exit(0);
398 } /* main */
399 
400 /*
401  * Redirects stdin/stdout to s, stderr to /dev/null and exec
402  * 'ppp -direct -quiet [-unit N] label'. Never returns.
403  */
404 
405 static void
406 exec_ppp(int s, char *unit, char *label)
407 {
408 	char	 ppp[] = "/usr/sbin/ppp";
409 	char	*ppp_args[] = { ppp,  "-direct", "-quiet",
410 				NULL, NULL,      NULL,     NULL };
411 
412 	close(0);
413 	if (dup(s) < 0) {
414 		syslog(LOG_ERR, "Could not dup(0). %s (%d)",
415 			strerror(errno), errno);
416 		exit(1);
417 	}
418 
419 	close(1);
420 	if (dup(s) < 0) {
421 		syslog(LOG_ERR, "Could not dup(1). %s (%d)",
422 			strerror(errno), errno);
423 		exit(1);
424 	}
425 
426 	close(2);
427 	open("/dev/null", O_RDWR);
428 
429 	if (unit != NULL) {
430 		ppp_args[3] = "-unit";
431 		ppp_args[4] = unit;
432 		ppp_args[5] = label;
433 	} else
434 		ppp_args[3] = label;
435 
436 	if (execv(ppp, ppp_args) < 0) {
437 		syslog(LOG_ERR, "Could not exec(%s -direct -quiet%s%s %s). " \
438 			"%s (%d)", ppp, (unit != NULL)? " -unit " : "",
439 			(unit != NULL)? unit : "", label,
440 			strerror(errno), errno);
441 		exit(1);
442 	}
443 } /* run_ppp */
444 
445 /* Signal handler */
446 static void
447 sighandler(int s)
448 {
449 	done = 1;
450 } /* sighandler */
451 
452 /* Display usage and exit */
453 static void
454 usage(void)
455 {
456 	fprintf(stdout,
457 "Usage: %s options\n" \
458 "Where options are:\n" \
459 "\t-a address   Address to listen on or connect to (required for client)\n" \
460 "\t-c           Act as a clinet (default)\n" \
461 "\t-C channel   RFCOMM channel to listen on or connect to (required)\n" \
462 "\t-d           Run in foreground\n" \
463 "\t-D           Register Dial-Up Networking service (server mode only)\n" \
464 "\t-l label     Use PPP label (required)\n" \
465 "\t-s           Act as a server\n" \
466 "\t-S           Register Serial Port service (server mode only)\n" \
467 "\t-u N         Tell PPP to operate on /dev/tunN (client mode only)\n" \
468 "\t-h           Display this message\n", RFCOMM_PPPD);
469 
470 	exit(255);
471 } /* usage */
472 
473