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