1 /*
2  * Copyright (c) 2019 Martijn van Duren <martijn@openbsd.org>
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 #include <sys/time.h>
17 #include <sys/socket.h>
18 
19 #include <arpa/inet.h>
20 #include <errno.h>
21 #include <event.h>
22 #include <fcntl.h>
23 #include <inttypes.h>
24 #include <stdarg.h>
25 #include <stdio.h>
26 #include <stdlib.h>
27 #include <string.h>
28 #include <syslog.h>
29 #include <unistd.h>
30 
31 #include "log.h"
32 #include "smtp_proc.h"
33 
34 #define NITEMS(x) (sizeof(x) / sizeof(*x))
35 
36 struct smtp_callback;
37 struct smtp_request;
38 
39 extern struct event_base *current_base;
40 
41 static int smtp_register(char *, char *, char *, void *);
42 static ssize_t smtp_getline(char ** restrict, size_t * restrict);
43 static void smtp_newline(int, short, void *);
44 static void smtp_connect(struct smtp_callback *, int, struct timespec *,
45     uint64_t, uint64_t, char *);
46 static void smtp_noargs(struct smtp_callback *, int, struct timespec *,
47     uint64_t, uint64_t, char *);
48 static void smtp_dataline(struct smtp_callback *, int, struct timespec *,
49     uint64_t, uint64_t, char *);
50 static void smtp_in_link_disconnect(struct smtp_callback *, int, struct timespec *,
51     uint64_t, char *);
52 static void smtp_printf(const char *, ...)
53 	__attribute__((__format__ (printf, 1, 2)));
54 static void smtp_vprintf(const char *, va_list);
55 static void smtp_write(int, short, void *);
56 
57 struct smtp_writebuf {
58 	char *buf;
59 	size_t bufsize;
60 	size_t buflen;
61 };
62 
63 struct smtp_callback {
64 	char *type;
65 	char *phase;
66 	char *direction;
67 	union {
68 		void (*smtp_filter)(struct smtp_callback *, int,
69 		    struct timespec *, uint64_t, uint64_t, char *);
70 		void (*smtp_report)(struct smtp_callback *, int,
71 		    struct timespec *, uint64_t, char *);
72 	};
73 	void *cb;
74 } smtp_callbacks[] = {
75         {"filter", "connect", "smtp-in", .smtp_filter = smtp_connect, NULL},
76         {"filter", "data", "smtp-in", .smtp_filter = smtp_noargs, NULL},
77         {"filter", "data-line", "smtp-in", .smtp_filter = smtp_dataline, NULL},
78         {"filter", "commit", "smtp-in", .smtp_filter = smtp_noargs, NULL},
79 	{"report", "link-disconnect", "smtp-in",
80 	    .smtp_report = smtp_in_link_disconnect, NULL}
81 };
82 
83 static int ready = 0;
84 
85 int
86 smtp_register_filter_connect(void (*cb)(char *, int, struct timespec *, char *,
87     char *, uint64_t, uint64_t, char *, struct inx_addr *))
88 {
89 	return smtp_register("filter", "connect", "smtp-in", (void *)cb);
90 }
91 
92 int
93 smtp_register_filter_data(void (*cb)(char *, int, struct timespec *, char *,
94     char *, uint64_t, uint64_t))
95 {
96 	return smtp_register("filter", "data", "smtp-in", (void *)cb);
97 }
98 
99 int
100 smtp_register_filter_dataline(void (*cb)(char *, int, struct timespec *, char *,
101     char *, uint64_t, uint64_t, char *))
102 {
103 	return smtp_register("filter", "data-line", "smtp-in", (void *)cb);
104 }
105 
106 int
107 smtp_register_filter_commit(void (*cb)(char *, int, struct timespec *, char *,
108     char *, uint64_t, uint64_t))
109 {
110 	return smtp_register("filter", "commit", "smtp-in", (void *)cb);
111 }
112 
113 int
114 smtp_in_register_report_disconnect(void (*cb)(char *, int, struct timespec *,
115     char *, char *, uint64_t))
116 {
117 	return smtp_register("report", "link-disconnect", "smtp-in", (void *)cb);
118 }
119 
120 void
121 smtp_run(int debug)
122 {
123 	struct event stdinev;
124 
125 	smtp_printf("register|ready\n");
126 	ready = 1;
127 
128 	log_init(debug, LOG_MAIL);
129 	event_set(&stdinev, STDIN_FILENO, EV_READ | EV_PERSIST, smtp_newline,
130 	    &stdinev);
131 	event_add(&stdinev, NULL);
132 
133 	if (fcntl(STDIN_FILENO, F_SETFL, O_NONBLOCK) == -1)
134 		fatal("fcntl");
135 	event_dispatch();
136 }
137 
138 static ssize_t
139 smtp_getline(char ** restrict buf, size_t * restrict size)
140 {
141 	static char *rbuf = NULL;
142 	static size_t rsoff = 0, reoff = 0;
143 	static size_t rbsize = 0;
144 	char *sep;
145 	size_t sepoff;
146 	ssize_t strlen, nread;
147 
148 	do {
149 		if (rsoff != reoff) {
150 			if ((sep = memchr(rbuf + rsoff, '\n', reoff - rsoff))
151 			    != NULL) {
152 				sepoff = sep - rbuf;
153 				if (*buf == NULL)
154 					*size = 0;
155 				if (*size < (sepoff - rsoff + 1)) {
156 					*size = sepoff - rsoff + 1;
157 					*buf = realloc(*buf, sepoff - rsoff + 1);
158 					if (*buf == NULL)
159 						fatal(NULL);
160 				}
161 				sep[0] = '\0';
162 				strlen = strlcpy(*buf, rbuf + rsoff, *size);
163 				if (strlen >= *size)
164 					fatalx("copy buffer too small");
165 				rsoff = sepoff + 1;
166 				return strlen;
167 			}
168 		}
169 		/* If we can't fill at the end, move everything back. */
170 		if (rbsize - reoff < 1500 && rsoff != 0) {
171 			memmove(rbuf, rbuf + rsoff, reoff - rsoff);
172 			reoff -= rsoff;
173 			rsoff = 0;
174 		}
175 		/* If we still can't fill alloc some new memory. */
176 		if (rbsize - reoff < 1500) {
177 			if ((rbuf = realloc(rbuf, rbsize + 4096)) == NULL)
178 				fatal(NULL);
179 			rbsize += 4096;
180 		}
181 		nread = read(STDIN_FILENO, rbuf + reoff, rbsize - reoff);
182 		if (nread <= 0)
183 			return nread;
184 		reoff += nread;
185 	} while (1);
186 }
187 
188 static void
189 smtp_newline(int fd, short event, void *arg)
190 {
191 	struct event *stdinev = (struct event *)arg;
192 	static char *line = NULL, *linedup = NULL;
193 	static size_t linesize = 0;
194 	static size_t dupsize = 0;
195 	ssize_t linelen;
196 	char *start, *end, *type, *direction, *phase, *params;
197 	int version;
198 	struct timespec tm;
199 	uint64_t reqid, token;
200 	int i;
201 
202 	while ((linelen = smtp_getline(&line, &linesize)) > 0) {
203 		if (dupsize < linesize) {
204 			if ((linedup = realloc(linedup, linesize)) == NULL)
205 				fatal(NULL);
206 			dupsize = linesize;
207 		}
208 		strlcpy(linedup, line, dupsize);
209 		type = line;
210 		if ((start = strchr(type, '|')) == NULL)
211 			fatalx("Invalid line received: missing version: %s", linedup);
212 		start++[0] = '\0';
213 		if ((end = strchr(start, '|')) == NULL)
214 			fatalx("Invalid line received: missing time: %s", linedup);
215 		end++[0] = '\0';
216 		if (strcmp(start, "1") != 0)
217 			fatalx("Unsupported protocol received: %s: %s", start, linedup);
218 		version = 1;
219 		start = end;
220 		if ((direction = strchr(start, '|')) == NULL)
221 			fatalx("Invalid line received: missing direction: %s", linedup);
222 		direction++[0] = '\0';
223 		tm.tv_sec = (time_t) strtoull(start, &end, 10);
224 		tm.tv_nsec = 0;
225 		if (start[0] == '\0' || (end[0] != '\0' && end[0] != '.'))
226 			fatalx("Invalid line received: invalid timestamp: %s", linedup);
227 		if (end[0] == '.') {
228 			start = end + 1;
229 			tm.tv_nsec = strtol(start, &end, 10);
230 			if (start[0] == '\0' || end[0] != '\0')
231 				fatalx("Invalid line received: invalid "
232 				    "timestamp: %s", linedup);
233 			for (i = 9 - (end - start); i > 0; i--)
234 				tm.tv_nsec *= 10;
235 		}
236 		if ((phase = strchr(direction, '|')) == NULL)
237 			fatalx("Invalid line receieved: missing phase: %s", linedup);
238 		phase++[0] = '\0';
239 		if ((start = strchr(phase, '|')) == NULL)
240 			fatalx("Invalid line received: missing reqid: %s", linedup);
241 		start++[0] = '\0';
242 		reqid = strtoull(start, &params, 16);
243 		if (start[0] == '|' || (params[0] != '|' & params[0] != '\0'))
244 			fatalx("Invalid line received: invalid reqid: %s", linedup);
245 		params++;
246 
247 		for (i = 0; i < NITEMS(smtp_callbacks); i++) {
248 			if (strcmp(type, smtp_callbacks[i].type) == 0 &&
249 			    strcmp(phase, smtp_callbacks[i].phase) == 0 &&
250 			    strcmp(direction, smtp_callbacks[i].direction) == 0)
251 				break;
252 		}
253 		if (i == NITEMS(smtp_callbacks)) {
254 			fatalx("Invalid line received: received unregistered "
255 			    "%s: %s: %s", type, phase, linedup);
256 		}
257 		if (strcmp(type, "filter") == 0) {
258 			start = params;
259 			token = strtoull(start, &params, 16);
260 			if (start[0] == '|' || params[0] != '|')
261 				fatalx("Invalid line received: invalid token: %s", linedup);
262 			params++;
263 			smtp_callbacks[i].smtp_filter(&(smtp_callbacks[i]),
264 			    version, &tm, reqid, token, params);
265 		} else
266 			smtp_callbacks[i].smtp_report(&(smtp_callbacks[i]),
267 			    version, &tm, reqid, params);
268 	}
269 	if (linelen == 0 || errno != EAGAIN)
270 		event_del(stdinev);
271 }
272 
273 static void
274 smtp_connect(struct smtp_callback *cb, int version, struct timespec *tm,
275     uint64_t reqid, uint64_t token, char *params)
276 {
277 	struct inx_addr addrx;
278 	char *hostname;
279 	char *address;
280 	int ret;
281 	void (*f)(char *, int, struct timespec *,char *, char *, uint64_t,
282 	    uint64_t, char *, struct inx_addr *);
283 
284 	hostname = params;
285 	if ((address = strchr(params, '|')) == NULL)
286 		fatalx("Invalid line received: missing address: %s", params);
287 	address++[0] = '\0';
288 
289 	addrx.af = AF_INET;
290 	if (strncasecmp(address, "ipv6:", 5) == 0) {
291 		addrx.af = AF_INET6;
292 		address += 5;
293 	}
294 
295 	ret = inet_pton(addrx.af, address, addrx.af == AF_INET ?
296 	    (void *)&(addrx.addr) : (void *)&(addrx.addr6));
297 	if (ret == 0)
298 		fatalx("Invalid line received: Couldn't parse address: %s", params);
299 	if (ret == -1)
300 		fatal("Couldn't convert address: %s", params);
301 
302 	f = cb->cb;
303 	f(cb->type, version, tm, cb->direction, cb->phase, reqid, token,
304 	    hostname, &addrx);
305 }
306 
307 static void
308 smtp_noargs(struct smtp_callback *cb, int version, struct timespec *tm,
309     uint64_t reqid, uint64_t token, char *params)
310 {
311 	void (*f)(char *, int, struct timespec *, char *, char *, uint64_t,
312 	    uint64_t);
313 
314 	f = cb->cb;
315 	f(cb->type, version, tm, cb->direction, cb->phase, reqid, token);
316 }
317 
318 static void
319 smtp_dataline(struct smtp_callback *cb, int version, struct timespec *tm,
320     uint64_t reqid, uint64_t token, char *line)
321 {
322 	void (*f)(char *, int, struct timespec *, char *, char *, uint64_t,
323 	    uint64_t, char *);
324 
325 	f = cb->cb;
326 	f(cb->type, version, tm, cb->direction, cb->phase, reqid, token,
327 	    line);
328 }
329 
330 static void
331 smtp_in_link_disconnect(struct smtp_callback *cb, int version,
332     struct timespec *tm, uint64_t reqid, char *params)
333 {
334 	void (*f)(char *, int, struct timespec *, char *, char *, uint64_t);
335 
336 	f = cb->cb;
337 	f(cb->type, version, tm, cb->direction, cb->phase, reqid);
338 }
339 
340 void
341 smtp_filter_proceed(uint64_t reqid, uint64_t token)
342 {
343 	smtp_printf("filter-result|%016"PRIx64"|%016"PRIx64"|proceed\n", token,
344 	    reqid);
345 }
346 
347 static void
348 smtp_printf(const char *fmt, ...)
349 {
350 	va_list ap;
351 
352 	va_start(ap, fmt);
353 	smtp_vprintf(fmt, ap);
354 	va_end(ap);
355 }
356 
357 static void
358 smtp_vprintf(const char *fmt, va_list ap)
359 {
360 	va_list cap;
361 	static struct smtp_writebuf buf = {NULL, 0, 0};
362 	int fmtlen;
363 
364 	va_copy(cap, ap);
365 	fmtlen = vsnprintf(buf.buf + buf.buflen, buf.bufsize - buf.buflen, fmt,
366 	    ap);
367 	if (fmtlen == -1)
368 		fatal("vsnprintf");
369 	if (fmtlen >= buf.bufsize - buf.buflen) {
370 		buf.bufsize = buf.buflen + fmtlen + 1;
371 		buf.buf = reallocarray(buf.buf, buf.bufsize,
372 		    sizeof(*(buf.buf)));
373 		if (buf.buf == NULL)
374 			fatal(NULL);
375 		fmtlen = vsnprintf(buf.buf + buf.buflen,
376 		    buf.bufsize - buf.buflen, fmt, cap);
377 		if (fmtlen == -1)
378 			fatal("vsnprintf");
379 	}
380 	va_end(cap);
381 	buf.buflen += fmtlen;
382 
383 	if (strchr(buf.buf, '\n') != NULL)
384 		smtp_write(STDOUT_FILENO, EV_WRITE, &buf);
385 }
386 
387 static void
388 smtp_write(int fd, short event, void *arg)
389 {
390 	struct smtp_writebuf *buf = arg;
391 	static struct event stdoutev;
392 	static int evset = 0;
393 	ssize_t wlen;
394 
395 	if (buf->buflen == 0)
396 		return;
397 	if (!evset) {
398 		event_set(&stdoutev, fd, EV_WRITE, smtp_write, buf);
399 		evset = 1;
400 	}
401 	wlen = write(fd, buf->buf, buf->buflen);
402 	if (wlen == -1) {
403 		if (errno != EAGAIN && errno != EINTR)
404 			fatal("Failed to write to smtpd");
405 		event_add(&stdoutev, NULL);
406 		return;
407 	}
408 	if (wlen < buf->buflen) {
409 		memmove(buf->buf, buf->buf + wlen, buf->buflen - wlen);
410 		event_add(&stdoutev, NULL);
411 	}
412 	buf->buflen -= wlen;
413 	if (buf->buflen == 0 && event_pending(&stdoutev, EV_WRITE, NULL))
414 		event_del(&stdoutev);
415 }
416 
417 void
418 smtp_filter_reject(uint64_t reqid, uint64_t token, int code,
419     const char *reason, ...)
420 {
421 	va_list ap;
422 
423 	if (code < 200 || code > 599)
424 		fatalx("Invalid reject code");
425 
426 	smtp_printf("filter-result|%016"PRIx64"|%016"PRIx64"|reject|%d ", token,
427 	    reqid, code);
428 	va_start(ap, reason);
429 	smtp_vprintf(reason, ap);
430 	va_end(ap);
431 	smtp_printf("\n");
432 }
433 
434 void
435 smtp_filter_disconnect(uint64_t reqid, uint64_t token, const char *reason, ...)
436 {
437 	va_list ap;
438 
439 	smtp_printf("filter-result|%016"PRIx64"|%016"PRIx64"|disconnect|421 ",
440 	    token, reqid);
441 	va_start(ap, reason);
442 	smtp_vprintf(reason, ap);
443 	va_end(ap);
444 	smtp_printf("\n");
445 }
446 
447 void
448 smtp_filter_dataline(uint64_t reqid, uint64_t token, const char *line, ...)
449 {
450 	va_list ap;
451 
452 	smtp_printf("filter-dataline|%016"PRIx64"|%016"PRIx64"|", token, reqid);
453 	va_start(ap, line);
454 	smtp_vprintf(line, ap);
455 	va_end(ap);
456 	smtp_printf("\n");
457 }
458 
459 static int
460 smtp_register(char *type, char *phase, char *direction, void *cb)
461 {
462 	int i;
463 	static int evinit = 0;
464 
465 	if (ready)
466 		fatalx("Can't register when proc is running");
467 
468 	if (!evinit) {
469 		event_init();
470 		evinit = 1;
471 	}
472 
473 	for (i = 0; i < NITEMS(smtp_callbacks); i++) {
474 		if (strcmp(type, smtp_callbacks[i].type) == 0 &&
475 		    strcmp(phase, smtp_callbacks[i].phase) == 0 &&
476 		    strcmp(direction, smtp_callbacks[i].direction) == 0) {
477 			if (smtp_callbacks[i].cb != NULL) {
478 				errno = EALREADY;
479 				return -1;
480 			}
481 			smtp_callbacks[i].cb = cb;
482 			smtp_printf("register|%s|%s|%s\n", type, direction,
483 			    phase);
484 			return 0;
485 		}
486 	}
487 	errno = EINVAL;
488 	return -1;
489 }