1 /*
2  * Copyright (c) 2020 Omar Polo <op@omarpolo.com>
3  *
4  * Permission to use, copy, modify, and distribute this software for any
5  * purpose with or without fee is hereby granted, provided that the above
6  * copyright notice and this permission notice appear in all copies.
7  *
8  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
15  */
16 
17 #include "gmid.h"
18 
19 #include <sys/stat.h>
20 
21 #include <errno.h>
22 #include <fcntl.h>
23 #include <limits.h>
24 #include <pwd.h>
25 #include <signal.h>
26 #include <string.h>
27 
28 volatile sig_atomic_t hupped;
29 
30 struct vhost hosts[HOSTSLEN];
31 
32 int exfd, sock4, sock6;
33 
34 const char *config_path, *certs_dir, *hostname;
35 
36 struct conf conf;
37 
38 struct tls_config *tlsconf;
39 struct tls *ctx;
40 
41 void
42 sig_handler(int sig)
43 {
44 	(void)sig;
45 
46 	hupped = sig == SIGHUP;
47 }
48 
49 /* XXX: create recursively */
50 void
51 mkdirs(const char *path)
52 {
53 	if (mkdir(path, 0755) == -1 && errno != EEXIST)
54 		fatal("can't mkdir %s: %s", path, strerror(errno));
55 }
56 
57 /* $XDG_DATA_HOME/gmid */
58 char *
59 data_dir(void)
60 {
61 	const char *home, *xdg;
62 	char *t;
63 
64 	if ((xdg = getenv("XDG_DATA_HOME")) == NULL) {
65 		if ((home = getenv("HOME")) == NULL)
66 			errx(1, "XDG_DATA_HOME and HOME both empty");
67 		if (asprintf(&t, "%s/.local/share/gmid", home) == -1)
68 			err(1, "asprintf");
69 		mkdirs(t);
70 		return t;
71 	}
72 
73 	if (asprintf(&t, "%s/gmid", xdg) == -1)
74 		err(1, "asprintf");
75 	mkdirs(t);
76 	return t;
77 }
78 
79 void
80 load_local_cert(const char *hostname, const char *dir)
81 {
82 	char *cert, *key;
83 
84 	if (asprintf(&cert, "%s/%s.cert.pem", dir, hostname) == -1)
85 		errx(1, "asprintf");
86 	if (asprintf(&key, "%s/%s.key.pem", dir, hostname) == -1)
87 		errx(1, "asprintf");
88 
89 	if (access(cert, R_OK) == -1 || access(key, R_OK) == -1)
90 		gen_certificate(hostname, cert, key);
91 
92 	hosts[0].cert = cert;
93 	hosts[0].key = key;
94 	hosts[0].domain = hostname;
95 }
96 
97 void
98 load_vhosts(void)
99 {
100 	struct vhost *h;
101 
102 	for (h = hosts; h->domain != NULL; ++h) {
103 		if ((h->dirfd = open(h->dir, O_RDONLY | O_DIRECTORY)) == -1)
104 			fatal("open %s for domain %s", h->dir, h->domain);
105 	}
106 }
107 
108 int
109 make_socket(int port, int family)
110 {
111 	int sock, v;
112 	struct sockaddr_in addr4;
113 	struct sockaddr_in6 addr6;
114 	struct sockaddr *addr;
115 	socklen_t len;
116 
117         switch (family) {
118 	case AF_INET:
119 		bzero(&addr4, sizeof(addr4));
120 		addr4.sin_family = family;
121 		addr4.sin_port = htons(port);
122 		addr4.sin_addr.s_addr = INADDR_ANY;
123 		addr = (struct sockaddr*)&addr4;
124 		len = sizeof(addr4);
125 		break;
126 
127 	case AF_INET6:
128 		bzero(&addr6, sizeof(addr6));
129 		addr6.sin6_family = AF_INET6;
130 		addr6.sin6_port = htons(port);
131 		addr6.sin6_addr = in6addr_any;
132 		addr = (struct sockaddr*)&addr6;
133 		len = sizeof(addr6);
134 		break;
135 
136 	default:
137 		/* unreachable */
138 		abort();
139 	}
140 
141 	if ((sock = socket(family, SOCK_STREAM, 0)) == -1)
142 		fatal("socket: %s", strerror(errno));
143 
144 	v = 1;
145 	if (setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &v, sizeof(v)) == -1)
146 		fatal("setsockopt(SO_REUSEADDR): %s", strerror(errno));
147 
148 	v = 1;
149 	if (setsockopt(sock, SOL_SOCKET, SO_REUSEPORT, &v, sizeof(v)) == -1)
150 		fatal("setsockopt(SO_REUSEPORT): %s", strerror(errno));
151 
152 	mark_nonblock(sock);
153 
154 	if (bind(sock, addr, len) == -1)
155 		fatal("bind: %s", strerror(errno));
156 
157 	if (listen(sock, 16) == -1)
158 		fatal("listen: %s", strerror(errno));
159 
160 	return sock;
161 }
162 
163 void
164 setup_tls(void)
165 {
166 	struct vhost *h;
167 
168 	if ((tlsconf = tls_config_new()) == NULL)
169 		fatal("tls_config_new");
170 
171 	/* optionally accept client certs, but don't try to verify them */
172 	tls_config_verify_client_optional(tlsconf);
173 	tls_config_insecure_noverifycert(tlsconf);
174 
175 	if (tls_config_set_protocols(tlsconf, conf.protos) == -1)
176 		fatal("tls_config_set_protocols");
177 
178 	if ((ctx = tls_server()) == NULL)
179 		fatal("tls_server failure");
180 
181 	/* we need to set something, then we can add how many key we want */
182 	if (tls_config_set_keypair_file(tlsconf, hosts->cert, hosts->key))
183 		fatal("tls_config_set_keypair_file failed for (%s, %s)",
184 		    hosts->cert, hosts->key);
185 
186 	for (h = &hosts[1]; h->domain != NULL; ++h) {
187 		if (tls_config_add_keypair_file(tlsconf, h->cert, h->key) == -1)
188 			fatal("failed to load the keypair (%s, %s)",
189 			    h->cert, h->key);
190 	}
191 
192 	if (tls_configure(ctx, tlsconf) == -1)
193 		fatal("tls_configure: %s", tls_error(ctx));
194 }
195 
196 static int
197 listener_main(void)
198 {
199 	drop_priv();
200 	unblock_signals();
201 	load_default_mime(&conf.mime);
202 	load_vhosts();
203 	loop(ctx, sock4, sock6);
204 	return 0;
205 }
206 
207 void
208 init_config(void)
209 {
210 	size_t i;
211 
212 	bzero(hosts, sizeof(hosts));
213 	for (i = 0; i < HOSTSLEN; ++i)
214 		hosts[i].dirfd = -1;
215 
216 	conf.port = 1965;
217 	conf.ipv6 = 0;
218 	conf.protos = TLS_PROTOCOL_TLSv1_2 | TLS_PROTOCOL_TLSv1_3;
219 
220 	init_mime(&conf.mime);
221 
222 	conf.chroot = NULL;
223 	conf.user = NULL;
224 
225 	/* we'll change this to 0 when running without config. */
226 	conf.prefork = 3;
227 }
228 
229 void
230 free_config(void)
231 {
232 	struct vhost *h;
233 	struct location *l;
234 
235 	free(conf.chroot);
236 	free(conf.user);
237 	memset(&conf, 0, sizeof(conf));
238 
239 	for (h = hosts; h->domain != NULL; ++h) {
240 		free((char*)h->domain);
241 		free((char*)h->cert);
242 		free((char*)h->key);
243 		free((char*)h->dir);
244 		free((char*)h->cgi);
245 		free((char*)h->entrypoint);
246 
247 		for (l = h->locations; l->match != NULL; ++l) {
248 			free((char*)l->match);
249 			free((char*)l->lang);
250 			free((char*)l->default_mime);
251 			free((char*)l->index);
252 			free((char*)l->block_fmt);
253 		}
254 	}
255 	memset(hosts, 0, sizeof(hosts));
256 
257 	tls_free(ctx);
258 	tls_config_free(tlsconf);
259 }
260 
261 static void
262 wait_sighup(void)
263 {
264 	sigset_t mask;
265 	int signo;
266 
267 	sigemptyset(&mask);
268 	sigaddset(&mask, SIGHUP);
269 	sigwait(&mask, &signo);
270 }
271 
272 void
273 drop_priv(void)
274 {
275 	struct passwd *pw = NULL;
276 
277 	if (conf.chroot != NULL && conf.user == NULL)
278 		fatal("can't chroot without an user to switch to after.");
279 
280 	if (conf.user != NULL) {
281 		if ((pw = getpwnam(conf.user)) == NULL)
282 			fatal("can't find user %s", conf.user);
283 	}
284 
285 	if (conf.chroot != NULL) {
286 		if (chroot(conf.chroot) != 0 || chdir("/") != 0)
287 			fatal("%s: %s", conf.chroot, strerror(errno));
288 	}
289 
290 	if (pw != NULL) {
291 		if (setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid) == -1)
292 			fatal("setresuid(%d): %s", pw->pw_uid,
293 			    strerror(errno));
294 	}
295 
296 	if (getuid() == 0)
297 		log_warn(NULL, "not a good idea to run a network daemon as root");
298 }
299 
300 static int
301 spawn_listeners(int *p)
302 {
303 	int i;
304 
305 	close(p[0]);
306 	exfd = p[1];
307 
308 	for (i = 0; i < conf.prefork -1; ++i) {
309 		switch (fork()) {
310 		case -1:
311 			fatal("fork: %s", strerror(errno));
312 		case 0:		/* child */
313 			setproctitle("server(%d)", i+1);
314 			return listener_main();
315 		}
316 	}
317 
318 	if (conf.prefork == 0)
319 		setproctitle("server");
320 	else
321 		setproctitle("server(%d)", conf.prefork);
322 	return listener_main();
323 }
324 
325 static void
326 usage(const char *me)
327 {
328 	fprintf(stderr,
329 	    "USAGE: %s [-fn] [-c config] | [-6h] [-d certs-dir] [-H host]"
330 	    "       [-p port] [-x cgi] [dir]\n",
331 	    me);
332 }
333 
334 static int
335 serve(int argc, char **argv, int *p)
336 {
337 	char path[PATH_MAX];
338 
339 	if (config_path == NULL) {
340 		if (hostname == NULL)
341 			hostname = "localhost";
342 		if (certs_dir == NULL)
343 			certs_dir = data_dir();
344 		load_local_cert(hostname, certs_dir);
345 
346 		hosts[0].domain = "*";
347 		hosts[0].locations[0].auto_index = 1;
348 		hosts[0].locations[0].match = "*";
349 
350 		switch (argc) {
351 		case 0:
352 			hosts[0].dir = getcwd(path, sizeof(path));
353 			break;
354 		case 1:
355 			hosts[0].dir = absolutify_path(argv[0]);
356 			break;
357 		default:
358 			usage(getprogname());
359 			return 1;
360 		}
361 
362 		log_notice(NULL, "serving %s on port %d", hosts[0].dir, conf.port);
363 	}
364 
365 	/* setup tls before dropping privileges: we don't want user
366 	 * to put private certs inside the chroot. */
367 	setup_tls();
368 
369 	switch (fork()) {
370 	case -1:
371 		fatal("fork: %s", strerror(errno));
372 
373 	case 0:			/* child */
374 		return spawn_listeners(p);
375 
376 	default:		/* parent */
377 		setproctitle("executor");
378 		close(p[1]);
379 		exfd = p[0];
380 		drop_priv();
381 		unblock_signals();
382 		return executor_main();
383 	}
384 }
385 
386 int
387 main(int argc, char **argv)
388 {
389 	int ch, p[2];
390 	int conftest = 0, configless = 0;
391 	int old_ipv6, old_port;
392 
393 	init_config();
394 
395 	while ((ch = getopt(argc, argv, "6c:d:fH:hnp:vx:")) != -1) {
396 		switch (ch) {
397 		case '6':
398 			conf.ipv6 = 1;
399 			configless = 1;
400 			break;
401 
402 		case 'c':
403 			config_path = absolutify_path(optarg);
404 			break;
405 
406 		case 'd':
407 			certs_dir = optarg;
408 			configless = 1;
409 			break;
410 
411 		case 'f':
412 			conf.foreground = 1;
413 			break;
414 
415 		case 'H':
416 			hostname = optarg;
417 			configless = 1;
418 			break;
419 
420 		case 'h':
421 			usage(*argv);
422 			return 0;
423 
424 		case 'n':
425 			conftest = 1;
426 			break;
427 
428 		case 'p':
429 			conf.port = parse_portno(optarg);
430 			configless = 1;
431 			break;
432 
433 		case 'v':
434 			conf.verbose++;
435 			break;
436 
437 		case 'x':
438 			/* drop the starting / (if any) */
439 			if (*optarg == '/')
440 				optarg++;
441 			hosts[0].cgi = optarg;
442 			configless = 1;
443 			break;
444 
445 		default:
446 			usage(*argv);
447 			return 1;
448 		}
449 	}
450 	argc -= optind;
451 	argv += optind;
452 
453 	if (config_path == NULL) {
454 		configless = 1;
455 		conf.foreground = 1;
456 		conf.prefork = 0;
457 		conf.verbose++;
458 	}
459 
460 	if (config_path != NULL && (argc > 0 || configless))
461 		err(1, "can't specify options in config mode.");
462 
463 	if (conftest) {
464 		parse_conf(config_path);
465 		puts("config OK");
466 		return 0;
467 	}
468 
469 	signal(SIGPIPE, SIG_IGN);
470 	signal(SIGCHLD, SIG_IGN);
471 
472 #ifdef SIGINFO
473 	signal(SIGINFO, sig_handler);
474 #endif
475 	signal(SIGUSR2, sig_handler);
476 	signal(SIGHUP, sig_handler);
477 
478 	if (!conf.foreground && !configless) {
479 		if (daemon(1, 1) == -1)
480 			fatal("daemon: %s", strerror(errno));
481 	}
482 
483 	if (socketpair(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC,
484 	    PF_UNSPEC, p) == -1)
485 		fatal("socketpair: %s", strerror(errno));
486 
487 	if (config_path != NULL)
488 		parse_conf(config_path);
489 
490 	sock4 = make_socket(conf.port, AF_INET);
491 	sock6 = -1;
492 	if (conf.ipv6)
493 		sock6 = make_socket(conf.port, AF_INET6);
494 
495 	if (configless)
496 		return serve(argc, argv, p);
497 
498 	/* wait a sighup and reload the daemon */
499 	for (;;) {
500 		block_signals();
501 
502 		hupped = 0;
503 		switch (fork()) {
504 		case -1:
505 			fatal("fork: %s", strerror(errno));
506 		case 0:
507 			return serve(argc, argv, p);
508 		}
509 
510 		close(p[0]);
511 		close(p[1]);
512 
513 		wait_sighup();
514 		unblock_signals();
515 		log_info(NULL, "reloading configuration %s", config_path);
516 
517 		old_ipv6 = conf.ipv6;
518 		old_port = conf.port;
519 
520 		free_config();
521 		init_config();
522 		parse_conf(config_path);
523 
524 		if (old_port != conf.port) {
525 			close(sock4);
526 			close(sock6);
527 			sock4 = -1;
528 			sock6 = -1;
529 		}
530 
531 		if (sock6 != -1 && old_ipv6 != conf.ipv6) {
532 			close(sock6);
533 			sock6 = -1;
534 		}
535 
536 		if (sock4 == -1)
537 			sock4 = make_socket(conf.port, AF_INET);
538 		if (sock6 == -1 && conf.ipv6)
539 			sock6 = make_socket(conf.port, AF_INET6);
540 
541 		if (socketpair(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC,
542 		    PF_UNSPEC, p) == -1)
543 			fatal("socketpair: %s", strerror(errno));
544 	}
545 }