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 <sys/socket.h>
18 #include <sys/stat.h>
19 
20 #include <netinet/in.h>
21 
22 #include <assert.h>
23 #include <err.h>
24 #include <fcntl.h>
25 #include <stdio.h>
26 #include <stdlib.h>
27 #include <string.h>
28 #include <tls.h>
29 #include <unistd.h>
30 
31 #ifndef __OpenBSD__
32 # define pledge(a, b) 0
33 # define unveil(a, b) 0
34 #endif /* __OpenBSD__ */
35 
36 #define GEMINI_URL_LEN (1024+3)	/* URL max len + \r\n + \0 */
37 
38 /* large enough to hold a copy of a gemini URL and still have extra room */
39 #define PATHBUF		2048
40 
41 #define FILEBUF		1024
42 
43 #define SUCCESS		20
44 #define NOT_FOUND	51
45 #define BAD_REQUEST	59
46 
47 int dirfd;
48 
49 char *
50 url_after_proto(char *url)
51 {
52 	char *s;
53 	const char *proto = "gemini";
54 	const char *marker = "://";
55 
56 	if ((s = strstr(url, marker)) == NULL)
57 		return url;
58 
59 	/* not a gemini:// URL */
60 
61 	if (s - strlen(proto) < url)
62 		return NULL;
63 	/* TODO: */
64 	/* if (strcmp(s - strlen(proto), proto)) */
65 	/* 	return NULL; */
66 
67 	/* a valid gemini:// URL */
68 	return s + strlen(marker);
69 }
70 
71 char *
72 url_start_of_request(char *url)
73 {
74 	char *s, *t;
75 
76 	if ((s = url_after_proto(url)) == NULL)
77 		return NULL;
78 
79 	if ((t = strstr(s, "/")) == NULL)
80 		return s + strlen(s);
81 	return t;
82 }
83 
84 int
85 url_trim(char *url)
86 {
87 	const char *e = "\r\n";
88 	char *s;
89 
90 	if ((s = strstr(url, e)) == NULL)
91 		return 0;
92 	s[0] = '\0';
93 	s[1] = '\0';
94 
95 	if (s[2] != '\0') {
96 		fprintf(stderr, "the request was longer than 1024 bytes\n");
97 		return 0;
98 	}
99 
100 	return 1;
101 }
102 
103 void
104 adjust_path(char *path)
105 {
106 	char *s;
107 	size_t len;
108 
109         /* /.. -> / */
110 	len = strlen(path);
111 	if (len >= 3) {
112 		if (!strcmp(&path[len-3], "/..")) {
113 			path[len-2] = '\0';
114 		}
115 	}
116 
117 	/* if the path is only `..` trim out and exit */
118 	if (!strcmp(path, "..")) {
119 		path[0] = '\0';
120 		return;
121 	}
122 
123 	/* remove every ../ in the path */
124 	while (1) {
125 		if ((s = strstr(path, "../")) == NULL)
126 			return;
127 		memmove(s, s+3, strlen(s)+1);	/* copy also the \0 */
128 	}
129 }
130 
131 int
132 path_isdir(char *path)
133 {
134 	if (*path == '\0')
135 		return 1;
136 	return path[strlen(path)-1] == '/';
137 }
138 
139 void
140 start_reply(struct tls *ctx, int code, const char *reason)
141 {
142 	char buf[1030] = {0}; 	/* status + ' ' + max reply len + \r\n\0 */
143 	int len;
144 
145 	len = snprintf(buf, sizeof(buf), "%d %s\r\n", code, reason);
146 	assert(len < (int)sizeof(buf));
147 	tls_write(ctx, buf, len);
148 }
149 
150 int
151 isdir(int fd)
152 {
153 	struct stat sb;
154 
155 	if (fstat(fd, &sb) == -1) {
156 		warn("fstat");
157 		return 1; 	/* we'll probably fail later on anyway */
158 	}
159 
160 	return S_ISDIR(sb.st_mode);
161 }
162 
163 void		 send_dir(char*, struct tls*);
164 
165 void
166 send_file(char *path, struct tls *ctx)
167 {
168 	int fd;
169 	char fpath[PATHBUF];
170 	char buf[FILEBUF];
171 	size_t i;
172 	ssize_t t, w;
173 
174 	bzero(fpath, sizeof(fpath));
175 
176 	if (*path != '.')
177 		fpath[0] = '.';
178 	
179 	strlcat(fpath, path, PATHBUF);
180 
181 	if ((fd = openat(dirfd, fpath, O_RDONLY | O_NOFOLLOW)) == -1) {
182 		warn("open: %s", fpath);
183 		start_reply(ctx, NOT_FOUND, "not found");
184 		return;
185 	}
186 
187 	if (isdir(fd)) {
188 		warnx("%s is a directory, trying %s/index.gmi", fpath, fpath);
189 		close(fd);
190 		send_dir(fpath, ctx);
191 		return;
192 	}
193 
194 	/* assume it's a text/gemini file */
195 	start_reply(ctx, SUCCESS, "text/gemini");
196 
197         while (1) {
198 		if ((w = read(fd, buf, sizeof(buf))) == -1) {
199 			warn("read: %s", fpath);
200 			goto exit;
201 		}
202 
203 		if (w == 0)
204 			break;
205 
206 		t = w;
207 		i = 0;
208 
209 		while (w > 0) {
210 			if ((t = tls_write(ctx, buf + i, w)) == -1) {
211 				warnx("tls_write (path=%s) : %s",
212 				    fpath,
213 				    tls_error(ctx));
214 				goto exit;
215 			}
216 			w -= t;
217 			i += t;
218 		}
219 	}
220 
221 exit:
222 	close(fd);
223 }
224 
225 void
226 send_dir(char *path, struct tls *ctx)
227 {
228 	char fpath[PATHBUF];
229 	size_t len;
230 
231 	bzero(fpath, PATHBUF);
232 
233 	if (*path != '.')
234 		fpath[0] = '.';
235 
236 	/* this cannot fail since sizeof(fpath) > maxlen of path */
237 	strlcat(fpath, path, PATHBUF);
238 	len = strlen(fpath);
239 
240 	/* add a trailing / in case. */
241 	if (fpath[len-1] != '/') {
242 		fpath[len] = '/';
243 	}
244 
245 	strlcat(fpath, "index.gmi", sizeof(fpath));
246 
247 	send_file(fpath, ctx);
248 }
249 
250 void
251 handle(char *url, struct tls *ctx)
252 {
253 	char *path;
254 
255 	if (!url_trim(url)) {
256 		start_reply(ctx, BAD_REQUEST, "bad request");
257 		return;
258 	}
259 
260 	if ((path = url_start_of_request(url)) == NULL) {
261 		start_reply(ctx, BAD_REQUEST, "bad request");
262 		return;
263 	}
264 
265 	adjust_path(path);
266 
267 	fprintf(stderr, "requested path: %s\n", path);
268 
269 	if (path_isdir(path))
270 		send_dir(path, ctx);
271 	else
272 		send_file(path, ctx);
273 }
274 
275 int
276 make_socket(int port)
277 {
278 	int sock, v;
279 	struct sockaddr_in addr;
280 
281 	if ((sock = socket(AF_INET, SOCK_STREAM, 0)) == -1)
282                 err(1, "socket");
283 
284 	v = 1;
285 	if (setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &v, sizeof(v)) == -1)
286 		err(1, "setsockopt(SO_REUSEADDR)");
287 
288 	v = 1;
289 	if (setsockopt(sock, SOL_SOCKET, SO_REUSEPORT, &v, sizeof(v)) == -1)
290 		err(1, "setsockopt(SO_REUSEPORT)");
291 
292 	bzero(&addr, sizeof(addr));
293 	addr.sin_family = AF_INET;
294 	addr.sin_port = htons(port);
295 	addr.sin_addr.s_addr = INADDR_ANY;
296 
297 	if (bind(sock, (struct sockaddr*)&addr, sizeof(addr)) == -1)
298                 err(1, "bind");
299 
300 	if (listen(sock, 16) == -1)
301                 err(1, "listen");
302 
303 	return sock;
304 }
305 
306 void
307 loop(struct tls *ctx, int sock)
308 {
309 	int fd;
310 	struct sockaddr_in client;
311 	socklen_t len;
312 	struct tls *clientctx;
313 	char buf[GEMINI_URL_LEN];
314 
315 	for (;;) {
316 		len = sizeof(client);
317 		if ((fd = accept(sock, (struct sockaddr*)&client, &len)) == -1)
318                         err(1, "accept");
319 
320 		if (tls_accept_socket(ctx, &clientctx, fd) == -1) {
321 			warnx("tls_accept_socket: %s", tls_error(ctx));
322 			continue;
323 		}
324 
325 		bzero(buf, GEMINI_URL_LEN);
326 		if (tls_read(clientctx, buf, sizeof(buf)-1) == -1) {
327 			warnx("tls_read: %s", tls_error(clientctx));
328 			goto clientend;
329 		}
330 
331 		handle(buf, clientctx);
332 
333 	clientend:
334 		if (tls_close(clientctx) == -1)
335 			warn("tls_close: client");
336 		tls_free(clientctx);
337 		close(fd);
338 	}
339 }
340 
341 void
342 usage(const char *me)
343 {
344 	fprintf(stderr,
345 	    "USAGE: %s [-h] [-c cert.pem] [-d docs] [-k key.pem]\n",
346 	    me);
347 }
348 
349 int
350 main(int argc, char **argv)
351 {
352 	const char *cert = "cert.pem", *key = "key.pem", *dir = "docs";
353 	struct tls *ctx = NULL;
354 	struct tls_config *conf;
355 	int sock, ch;
356 
357 	while ((ch = getopt(argc, argv, "c:d:hk:")) != -1) {
358 		switch (ch) {
359 		case 'c':
360 			cert = optarg;
361 			break;
362 
363 		case 'd':
364 			dir = optarg;
365 			break;
366 
367 		case 'h':
368 			usage(*argv);
369 			return 0;
370 
371 		case 'k':
372 			key = optarg;
373 			break;
374 
375 		default:
376 			usage(*argv);
377 			return 1;
378 		}
379 	}
380 
381 	if ((conf = tls_config_new()) == NULL)
382 		err(1, "tls_config_new");
383 
384 	if (tls_config_set_protocols(conf,
385 	    TLS_PROTOCOL_TLSv1_2 | TLS_PROTOCOL_TLSv1_3) == -1)
386 		err(1, "tls_config_set_protocols");
387 
388 	if (tls_config_set_cert_file(conf, cert) == -1)
389 		err(1, "tls_config_set_cert_file: %s", cert);
390 
391 	if (tls_config_set_key_file(conf, key) == -1)
392 		err(1, "tls_config_set_key_file: %s", key);
393 
394 	if ((ctx = tls_server()) == NULL)
395 		err(1, "tls_server");
396 
397 	if (tls_configure(ctx, conf) == -1)
398 		errx(1, "tls_configure: %s", tls_error(ctx));
399 
400 	sock = make_socket(1965);
401 
402 	if ((dirfd = open(dir, O_RDONLY | O_DIRECTORY)) == -1)
403 		err(1, "open: %s", dir);
404 
405 	if (unveil(dir, "r") == -1)
406 		err(1, "unveil");
407 
408 	if (pledge("stdio rpath inet", "") == -1)
409 		err(1, "pledge");
410 
411 	loop(ctx, sock);
412 
413 	close(sock);
414 	tls_free(ctx);
415 	tls_config_free(conf);
416 }