1 /* vi: set sw=4 ts=4: */
3 * bare bones sendmail/fetchmail
5 * Copyright (C) 2008 by Vladimir Dronnikov <dronnikov@gmail.com>
7 * Licensed under GPLv2, see file LICENSE in this tarball for details.
11 #define INITIAL_STDIN_FILENO 3
13 static void uuencode(char *fname, const char *text)
16 SRC_BUF_SIZE = 45, /* This *MUST* be a multiple of 3 */
17 DST_BUF_SIZE = 4 * ((SRC_BUF_SIZE + 2) / 3),
23 char dst_buf[DST_BUF_SIZE + 1];
26 fd = INITIAL_STDIN_FILENO;
27 if (NOT_LONE_DASH(fname))
28 fd = xopen(fname, O_RDONLY);
29 src_buf = bb_common_bufsiz1;
30 // N.B. strlen(NULL) segfaults!
32 // though we do not call uuencode(NULL, NULL) explicitly
33 // still we do not want to break things suddenly
38 fflush(stdout); // sync stdio and unistd output
42 size = full_read(fd, (char *)src_buf, SRC_BUF_SIZE);
43 if ((ssize_t)size < 0)
44 bb_perror_msg_and_die(bb_msg_read_error);
47 if (len > SRC_BUF_SIZE)
52 // encode the buffer we just read in
53 bb_uuencode(dst_buf, src_buf, size, bb_uuenc_tbl_base64);
55 xwrite(STDOUT_FILENO, "\r\n", 2);
60 xwrite(STDOUT_FILENO, dst_buf, 4 * ((size + 2) / 3));
71 // arguments for SSL connection helper
73 // arguments for postprocess helper
76 #define G (*ptr_to_globals)
77 #define helper_pid (G.helper_pid)
78 #define timeout (G.timeout )
79 #define xargs (G.xargs )
80 #define fargs (G.fargs )
81 #define INIT_G() do { \
82 SET_PTR_TO_GLOBALS(xzalloc(sizeof(G))); \
83 xargs[0] = "openssl"; \
84 xargs[1] = "s_client"; \
85 xargs[2] = "-quiet"; \
86 xargs[3] = "-connect"; \
87 /*xargs[4] = "localhost";*/ \
89 xargs[6] = "-starttls"; \
94 #define opt_connect (xargs[4])
95 #define opt_after_connect (xargs[5])
96 #define opt_charset (fargs[0])
97 #define opt_subject (fargs[1])
99 static void kill_helper(void)
101 // TODO!!!: is there more elegant way to terminate child on program failure?
103 kill(helper_pid, SIGTERM);
106 // generic signal handler
107 static void signal_handler(int signo)
111 if (SIGALRM == signo) {
113 bb_error_msg_and_die("timed out");
116 // SIGCHLD. reap zombies
117 if (wait_any_nohang(&err) > 0)
118 if (WIFEXITED(err) && WEXITSTATUS(err))
119 bb_error_msg_and_die("child exited (%d)", WEXITSTATUS(err));
123 static void launch_helper(const char **argv)
125 // setup vanilla unidirectional pipes interchange
131 helper_pid = xvfork();
132 idx = (!helper_pid) * 2;
133 xdup2(pipes[idx], STDIN_FILENO);
134 xdup2(pipes[3-idx], STDOUT_FILENO);
135 if (ENABLE_FEATURE_CLEAN_UP)
136 for (int i = 4; --i >= 0; )
137 if (pipes[i] > STDOUT_FILENO)
140 // child: try to execute connection helper
141 BB_EXECVP(*argv, (char **)argv);
144 // parent: check whether child is alive
149 signal_handler(SIGCHLD);
150 // child seems OK -> parent goes on
153 static const char *command(const char *fmt, const char *param)
155 const char *msg = fmt;
158 msg = xasprintf(fmt, param);
159 printf("%s\r\n", msg);
165 static int smtp_checkp(const char *fmt, const char *param, int code)
168 const char *msg = command(fmt, param);
170 // if the string has a form \d\d\d- -- read next string. E.g. EHLO response
171 // parse first bytes to a number
172 // if code = -1 then just return this number
173 // if code != -1 then checks whether the number equals the code
174 // if not equal -> die saying msg
175 while ((answer = xmalloc_fgetline(stdin)) != NULL)
176 if (strlen(answer) <= 3 || '-' != answer[3])
179 int n = atoi(answer);
181 if (ENABLE_FEATURE_CLEAN_UP) {
184 if (-1 == code || n == code) {
189 bb_error_msg_and_die("%s failed", msg);
192 static inline int smtp_check(const char *fmt, int code)
194 return smtp_checkp(fmt, NULL, code);
197 // strip argument of bad chars
198 static char *sane(char *str)
203 if (isalnum(*s) || '_' == *s || '-' == *s || '.' == *s || '@' == *s) {
213 static void pop3_checkr(const char *fmt, const char *param, char **ret)
215 const char *msg = command(fmt, param);
216 char *answer = xmalloc_fgetline(stdin);
217 if (answer && '+' == *answer) {
220 *ret = answer+4; // skip "+OK "
221 else if (ENABLE_FEATURE_CLEAN_UP)
226 bb_error_msg_and_die("%s failed", msg);
229 static inline void pop3_check(const char *fmt, const char *param)
231 pop3_checkr(fmt, param, NULL);
234 static void pop3_message(const char *filename)
238 // create and open file filename
239 // read stdin, copy to created file
240 fd = xopen(filename, O_CREAT | O_WRONLY | O_TRUNC | O_EXCL);
241 while ((answer = xmalloc_fgets_str(stdin, "\r\n")) != NULL) {
243 if ('.' == *answer) {
244 if ('.' == answer[1])
246 else if ('\r' == answer[1] && '\n' == answer[2] && '\0' == answer[3])
249 xwrite(fd, s, strlen(s));
256 static char *parse_url(char *url, char **user, char **pass)
258 // parse [user[:pass]@]host
260 char *s = strchr(url, '@');
261 *user = *pass = NULL;
266 s = strchr(*user, ':');
275 int sendgetmail_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
276 int sendgetmail_main(int argc ATTRIBUTE_UNUSED, char **argv)
278 llist_t *opt_recipients = NULL;
279 llist_t *opt_attachments = NULL;
284 OPT_w = 1 << 0, // network timeout
285 OPT_H = 1 << 1, // [user:password@]server[:port]
286 OPT_S = 1 << 2, // connect using openssl s_client helper
288 OPTS_t = 1 << 3, // sendmail: read addresses from body
289 OPTF_t = 1 << 3, // fetchmail: use "TOP" not "RETR"
291 OPTS_s = 1 << 4, // sendmail: subject
292 OPTF_z = 1 << 4, // fetchmail: delete from server
294 OPTS_c = 1 << 5, // sendmail: assumed charset
295 OPTS_a = 1 << 6, // sendmail: attachment(s)
296 OPTS_i = 1 << 7, // sendmail: ignore lone dots in message body (implied)
298 OPTS_N = 1 << 8, // sendmail: request notification
299 OPTS_f = 1 << 9, // sendmail: sender address
304 // init global variables
307 // parse options, different option sets for sendmail and fetchmail
308 // N.B. opt_after_connect hereafter is NULL if we are called as fetchmail
309 // and is NOT NULL if we are called as sendmail
310 if (!ENABLE_FETCHMAIL || 's' == applet_name[0]) {
312 // save initial stdin since body is piped!
313 xdup2(STDIN_FILENO, INITIAL_STDIN_FILENO);
314 opt_complementary = "w+:a::";
315 options = "w:H:St" "s:c:a:iN:f:";
316 // body is pseudo attachment read from stdin
317 llist_add_to_end(&opt_attachments, (char *)"-");
320 opt_after_connect = NULL;
321 opt_complementary = "-1:w+";
322 options = "w:H:St" "z";
324 opts = getopt32(argv, options,
325 &timeout /* -w */, &opt_connect /* -H */,
326 &opt_subject, &opt_charset, &opt_attachments, NULL, &opt_from
332 // host[:port] not specified ? -> use $HOSTNAME. no $HOSTNAME ? -> use localhost
333 if (!(opts & OPT_H)) {
334 opt_connect = getenv("HOSTNAME");
336 opt_connect = "127.0.0.1";
338 // fetch username and password, if any
339 // NB: parse_url modifies opt_connect[] ONLY if '@' is there.
340 // Thus "127.0.0.1" won't be modified, an is ok that it is RO.
341 opt_connect = parse_url((char*)opt_connect, &opt_user, &opt_pass);
342 // bb_error_msg("H[%s] U[%s] P[%s]", opt_connect, opt_user, opt_pass);
344 // username must be defined!
346 // N.B. IMHO getenv("USER") can be way easily spoofed!
347 opt_user = bb_getpwuid(NULL, -1, getuid());
352 // ... use openssl helper
353 launch_helper(xargs);
354 // no SSL ordered? ->
356 // ... make plain connect
357 int fd = create_and_connect_stream_or_die(opt_connect, 25);
358 // make ourselves a simple IO filter
359 // from now we know nothing about network :)
360 xmove_fd(fd, STDIN_FILENO);
361 xdup2(STDIN_FILENO, STDOUT_FILENO);
365 if (!ENABLE_FETCHMAIL || opt_after_connect)
366 /***************************************************
368 ***************************************************/
377 // recipients specified as arguments
379 // loose test on email address validity
380 if (strchr(sane(*argv), '@'))
381 llist_add_to_end(&opt_recipients, *argv);
385 // if -t specified or no recipients specified -> enter all-included mode
386 // i.e. scan stdin for To: and Subject: lines ...
387 // ... and then use the rest of stdin as message body
388 // N.B. subject read from body has priority
389 // over that specified on command line.
390 // recipients are merged
391 if (opts & OPTS_t || !opt_recipients) {
392 // fetch recipients and (optionally) subject
394 while ((s = xmalloc_reads(INITIAL_STDIN_FILENO, NULL, NULL)) != NULL) {
395 if (0 == strncmp("To: ", s, 4)) {
396 llist_add_to_end(&opt_recipients, s+4);
397 /* } else if (0 == strncmp("From: ", s, 6)) {
400 */ } else if (0 == strncmp("Subject: ", s, 9)) {
412 // got no sender address? -> use username as a resort
413 if (!(opts & OPTS_f)) {
414 char *domain = safe_getdomainname();
415 opt_from = xasprintf("%s@%s", opt_user, domain);
419 // introduce to server
421 // we didn't use SSL helper? ->
422 if (!(opts & OPT_S)) {
423 // ... wait for initial server OK
424 smtp_check(NULL, 220);
427 // we should start with modern EHLO
428 if (250 != smtp_checkp("EHLO %s", sane(opt_from), -1)) {
429 smtp_checkp("HELO %s", opt_from, 250);
433 // NOTE: if password has not been specified
434 // then no authentication is possible
435 code = (opt_pass) ? -1 : 250;
436 // first try softly without authentication
437 while (250 != smtp_checkp("MAIL FROM:<%s>", opt_from, code)) {
438 // MAIL FROM failed -> authentication needed
439 if (334 == smtp_check("AUTH LOGIN", -1)) {
440 uuencode(NULL, opt_user); // opt_user != NULL
442 uuencode(NULL, opt_pass);
445 // authenticated OK? -> retry to set sender
446 // but this time die on failure!
451 for (l = opt_recipients; l; l = l->link) {
452 smtp_checkp("RCPT TO:<%s>", sane(l->data), 250);
455 // enter "put message" mode
456 smtp_check("DATA", 354);
458 // put address headers
459 printf("From: %s\r\n", opt_from);
460 for (l = opt_recipients; l; l = l->link) {
461 printf("To: %s\r\n", l->data);
464 // put encoded subject
466 sane((char *)opt_charset);
468 printf("Subject: =?%s?B?", opt_charset);
469 uuencode(NULL, opt_subject);
475 printf("Disposition-Notification-To: %s\r\n", opt_from);
477 // make a random string -- it will delimit message parts
478 srand(monotonic_us());
479 boundary = xasprintf("%d-%d-%d", rand(), rand(), rand());
481 // put common headers and body start
483 "Message-ID: <%s>\r\n"
484 "Mime-Version: 1.0\r\n"
485 "%smultipart/mixed; boundary=\"%s\"\r\n"
491 // put body + attachment(s)
492 // N.B. all these weird things just to be tiny
493 // by reusing string patterns!
496 "%stext/plain; charset=%s\r\n"
509 , "Content-Disposition: inline"
511 , "Content-Transfer-Encoding: base64\r\n"
516 "%sapplication/octet-stream%s\r\n"
517 "%s; filename=\"%s\"\r\n"
520 uuencode(l->data, NULL);
523 q = bb_get_last_path_component_strip(l->data);
526 // put message terminator
527 printf("\r\n--%s--\r\n" "\r\n", boundary);
529 // leave "put message" mode
530 smtp_check(".", 250);
531 // ... and say goodbye
532 smtp_check("QUIT", 221);
535 /***************************************************
537 ***************************************************/
544 // cache fetch command:
545 // TOP will return only the headers
546 // RETR will dump the whole message
547 const char *retr = (opts & OPTF_t) ? "TOP %u 0" : "RETR %u";
552 // cache postprocess program
557 // password is mandatory
559 bb_error_msg_and_die("no password");
562 // get server greeting
563 pop3_checkr(NULL, NULL, &buf);
565 // server supports APOP?
568 // yes! compose <stamp><password>
569 char *s = strchr(buf, '>');
571 strcpy(s+1, opt_pass);
573 // get md5 sum of <stamp><password>
575 md5_hash(s, strlen(s), &md5);
577 // NOTE: md5 struct contains enough space
578 // so we reuse md5 space instead of xzalloc(16*2+1)
579 #define md5_hex ((uint8_t *)&md5)
580 // uint8_t *md5_hex = (uint8_t *)&md5;
581 *bin2hex((char *)md5_hex, s, 16) = '\0';
583 s = xasprintf("%s %s", opt_user, md5_hex);
585 pop3_check("APOP %s", s);
586 if (ENABLE_FEATURE_CLEAN_UP) {
588 free(buf-4); // buf is "+OK " away from malloc'ed string
590 // server ignores APOP -> use simple text authentication
593 pop3_check("USER %s", opt_user);
595 pop3_check("PASS %s", opt_pass);
598 // get mailbox statistics
599 pop3_checkr("STAT", NULL, &buf);
601 // prepare message filename suffix
602 hostname = safe_gethostname();
605 // get messages counter
606 // NOTE: we don't use xatou(buf) since buf is "nmsg nbytes"
607 // we only need nmsg and atoi is just exactly what we need
608 // if atoi fails to convert buf into number it returns 0
609 // in this case the following loop simply will not be executed
611 if (ENABLE_FEATURE_CLEAN_UP)
612 free(buf-4); // buf is "+OK " away from malloc'ed string
614 // loop through messages
615 for (; nmsg; nmsg--) {
617 // generate unique filename
618 char *filename = xasprintf("tmp/%llu.%u.%s",
619 monotonic_us(), (unsigned)pid, hostname);
623 // retrieve message in ./tmp/
624 pop3_check(retr, (const char *)(ptrdiff_t)nmsg);
625 pop3_message(filename);
626 // delete message from server
628 pop3_check("DELE %u", (const char*)(ptrdiff_t)nmsg);
630 // run postprocessing program
633 rc = wait4pid(spawn((char **)fargs));
640 // atomically move message to ./new/
641 target = xstrdup(filename);
642 strncpy(target, "new", 3);
643 // ... or just stop receiving on error
644 if (rename_or_warn(filename, target))
652 pop3_check("QUIT", NULL);
654 #endif // ENABLE_FETCHMAIL