vcs.maemo.org Git - busybox4maemo/blob - networking/sendmail.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * bare bones sendmail/fetchmail
   4  *
   5  * Copyright (C) 2008 by Vladimir Dronnikov <dronnikov@gmail.com>
   6  *
   7  * Licensed under GPLv2, see file LICENSE in this tarball for details.
   8  */
   9 #include "libbb.h"
  10
  11 #define INITIAL_STDIN_FILENO 3
  12
  13 static void uuencode(char *fname, const char *text)
  14 {
  15         enum {
  16                 SRC_BUF_SIZE = 45,  /* This *MUST* be a multiple of 3 */
  17                 DST_BUF_SIZE = 4 * ((SRC_BUF_SIZE + 2) / 3),
  18         };
  19
  20 #define src_buf text
  21         int fd;
  22 #define len fd
  23         char dst_buf[DST_BUF_SIZE + 1];
  24
  25         if (fname) {
  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!
  31         } else if (text) {
  32                 // though we do not call uuencode(NULL, NULL) explicitly
  33                 // still we do not want to break things suddenly
  34                 len = strlen(text);
  35         } else
  36                 return;
  37
  38         fflush(stdout); // sync stdio and unistd output
  39         while (1) {
  40                 size_t size;
  41                 if (fname) {
  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);
  45                 } else {
  46                         size = len;
  47                         if (len > SRC_BUF_SIZE)
  48                                 size = SRC_BUF_SIZE;
  49                 }
  50                 if (!size)
  51                         break;
  52                 // encode the buffer we just read in
  53                 bb_uuencode(dst_buf, src_buf, size, bb_uuenc_tbl_base64);
  54                 if (fname) {
  55                         xwrite(STDOUT_FILENO, "\r\n", 2);
  56                 } else {
  57                         src_buf += size;
  58                         len -= size;
  59                 }
  60                 xwrite(STDOUT_FILENO, dst_buf, 4 * ((size + 2) / 3));
  61         }
  62         if (fname)
  63                 close(fd);
  64 }
  65
  66 struct globals {
  67         pid_t helper_pid;
  68         unsigned timeout;
  69         // arguments for SSL connection helper
  70         const char *xargs[9];
  71         // arguments for postprocess helper
  72         const char *fargs[3];
  73 };
  74 #define G (*ptr_to_globals)
  75 #define helper_pid      (G.helper_pid)
  76 #define timeout         (G.timeout   )
  77 #define xargs           (G.xargs     )
  78 #define fargs           (G.fargs     )
  79 #define INIT_G() do { \
  80         SET_PTR_TO_GLOBALS(xzalloc(sizeof(G))); \
  81         xargs[0] = "openssl"; \
  82         xargs[1] = "s_client"; \
  83         xargs[2] = "-quiet"; \
  84         xargs[3] = "-connect"; \
  85         /*xargs[4] = "server[:port]";*/ \
  86         xargs[5] = "-tls1"; \
  87         xargs[6] = "-starttls"; \
  88         xargs[7] = "smtp"; \
  89         fargs[0] = "utf-8"; \
  90 } while (0)
  91
  92 #define opt_connect       (xargs[4])
  93 #define opt_after_connect (xargs[5])
  94 #define opt_charset       (fargs[0])
  95 #define opt_subject       (fargs[1])
  96
  97 static void kill_helper(void)
  98 {
  99         // TODO!!!: is there more elegant way to terminate child on program failure?
 100         if (helper_pid > 0)
 101                 kill(helper_pid, SIGTERM);
 102 }
 103
 104 // generic signal handler
 105 static void signal_handler(int signo)
 106 {
 107 #define err signo
 108
 109         if (SIGALRM == signo) {
 110                 kill_helper();
 111                 bb_error_msg_and_die("timed out");
 112         }
 113
 114         // SIGCHLD. reap zombies
 115         if (wait_any_nohang(&err) > 0)
 116                 if (WIFEXITED(err) && WEXITSTATUS(err))
 117                         bb_error_msg_and_die("child exited (%d)", WEXITSTATUS(err));
 118 }
 119
 120 static void launch_helper(const char **argv)
 121 {
 122         // setup vanilla unidirectional pipes interchange
 123         int idx;
 124         int pipes[4];
 125         xpipe(pipes);
 126         xpipe(pipes+2);
 127         helper_pid = vfork();
 128         if (helper_pid < 0)
 129                 bb_perror_msg_and_die("vfork");
 130         idx = (!helper_pid)*2;
 131         xdup2(pipes[idx], STDIN_FILENO);
 132         xdup2(pipes[3-idx], STDOUT_FILENO);
 133         if (ENABLE_FEATURE_CLEAN_UP)
 134                 for (int i = 4; --i >= 0; )
 135                         if (pipes[i] > STDOUT_FILENO)
 136                                 close(pipes[i]);
 137         if (!helper_pid) {
 138                 // child: try to execute connection helper
 139                 BB_EXECVP(*argv, (char **)argv);
 140                 _exit(127);
 141         }
 142         // parent: check whether child is alive
 143         bb_signals(0
 144                 + (1 << SIGCHLD)
 145                 + (1 << SIGALRM)
 146                 , signal_handler);
 147         signal_handler(SIGCHLD);
 148         // child seems OK -> parent goes on
 149 }
 150
 151 static const char *command(const char *fmt, const char *param)
 152 {
 153         const char *msg = fmt;
 154         alarm(timeout);
 155         if (msg) {
 156                 msg = xasprintf(fmt, param);
 157                 printf("%s\r\n", msg);
 158         }
 159         fflush(stdout);
 160         return msg;
 161 }
 162
 163 static int smtp_checkp(const char *fmt, const char *param, int code)
 164 {
 165         char *answer;
 166         const char *msg = command(fmt, param);
 167         // read stdin
 168         // if the string has a form \d\d\d- -- read next string. E.g. EHLO response
 169         // parse first bytes to a number
 170         // if code = -1 then just return this number
 171         // if code != -1 then checks whether the number equals the code
 172         // if not equal -> die saying msg
 173         while ((answer = xmalloc_getline(stdin)) != NULL)
 174                 if (strlen(answer) <= 3 || '-' != answer[3])
 175                         break;
 176         if (answer) {
 177                 int n = atoi(answer);
 178                 alarm(0);
 179                 if (ENABLE_FEATURE_CLEAN_UP) {
 180                         free(answer);
 181                 }
 182                 if (-1 == code || n == code) {
 183                         return n;
 184                 }
 185         }
 186         kill_helper();
 187         bb_error_msg_and_die("%s failed", msg);
 188 }
 189
 190 static int inline smtp_check(const char *fmt, int code)
 191 {
 192         return smtp_checkp(fmt, NULL, code);
 193 }
 194
 195 // strip argument of bad chars
 196 static char *sane(char *str)
 197 {
 198         char *s = str;
 199         char *p = s;
 200         while (*s) {
 201                 if (isalnum(*s) || '_' == *s || '-' == *s || '.' == *s || '@' == *s) {
 202                         *p++ = *s;
 203                 }
 204                 s++;
 205         }
 206         *p = '\0';
 207         return str;
 208 }
 209
 210 #if ENABLE_FETCHMAIL
 211 static void pop3_checkr(const char *fmt, const char *param, char **ret)
 212 {
 213         const char *msg = command(fmt, param);
 214         char *answer = xmalloc_getline(stdin);
 215         if (answer && '+' == *answer) {
 216                 alarm(0);
 217                 if (ret)
 218                         *ret = answer+4; // skip "+OK "
 219                 else if (ENABLE_FEATURE_CLEAN_UP)
 220                         free(answer);
 221                 return;
 222         }
 223         kill_helper();
 224         bb_error_msg_and_die("%s failed", msg);
 225 }
 226
 227 static void inline pop3_check(const char *fmt, const char *param)
 228 {
 229         pop3_checkr(fmt, param, NULL);
 230 }
 231
 232 static void pop3_message(const char *filename)
 233 {
 234         int fd;
 235         char *answer;
 236         // create and open file filename
 237         // read stdin, copy to created file
 238         fd = xopen(filename, O_CREAT | O_WRONLY | O_TRUNC | O_EXCL);
 239         while ((answer = xmalloc_fgets_str(stdin, "\r\n")) != NULL) {
 240                 char *s = answer;
 241                 if ('.' == *answer) {
 242                         if ('.' == answer[1])
 243                                 s++;
 244                         else if ('\r' == answer[1] && '\n' == answer[2] && '\0' == answer[3])
 245                                 break;
 246                 }
 247                 xwrite(fd, s, strlen(s));
 248                 free(answer);
 249         }
 250         close(fd);
 251 }
 252 #endif
 253
 254 int sendgetmail_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 255 int sendgetmail_main(int argc ATTRIBUTE_UNUSED, char **argv)
 256 {
 257         llist_t *opt_recipients = NULL;
 258
 259         const char *opt_user;
 260         const char *opt_pass;
 261
 262         enum {
 263                 OPT_w = 1 << 0,         // network timeout
 264                 OPT_U = 1 << 1,         // user
 265                 OPT_P = 1 << 2,         // password
 266                 OPT_X = 1 << 3,         // connect using openssl s_client helper
 267
 268                 OPTS_n = 1 << 4,        // sendmail: request notification
 269                 OPTF_t = 1 << 4,        // fetchmail: use "TOP" not "RETR"
 270
 271                 OPTS_s = 1 << 5,        // sendmail: subject
 272                 OPTF_z = 1 << 5,        // fetchmail: delete from server
 273
 274                 OPTS_c = 1 << 6,        // sendmail: assumed charset
 275                 OPTS_t = 1 << 7,        // sendmail: recipient(s)
 276         };
 277
 278         const char *options;
 279         unsigned opts;
 280
 281         // init global variables
 282         INIT_G();
 283
 284         // parse options, different option sets for sendmail and fetchmail
 285         // N.B. opt_after_connect hereafter is NULL if we are called as fetchmail
 286         // and is NOT NULL if we are called as sendmail
 287         if (!ENABLE_FETCHMAIL || 's' == applet_name[0]) {
 288                 // SENDMAIL
 289                 // save initial stdin (body or attachements can be piped!)
 290                 xdup2(STDIN_FILENO, INITIAL_STDIN_FILENO);
 291                 opt_complementary = "-2:w+:t:t::"; // count(-t) > 0
 292                 options = "w:U:P:X" "ns:c:t:";
 293         } else {
 294                 // FETCHMAIL
 295                 opt_after_connect = NULL;
 296                 opt_complementary = "-2:w+:P";
 297                 options = "w:U:P:X" "tz";
 298         }
 299         opts = getopt32(argv, options,
 300                 &timeout, &opt_user, &opt_pass,
 301                 &opt_subject, &opt_charset, &opt_recipients
 302         );
 303         //argc -= optind;
 304         argv += optind;
 305
 306         // first argument is remote server[:port]
 307         opt_connect = *argv++;
 308
 309         // connect to server
 310         // SSL ordered? ->
 311         if (opts & OPT_X) {
 312                 // ... use openssl helper
 313                 launch_helper(xargs);
 314         // no SSL ordered? ->
 315         } else {
 316                 // ... make plain connect
 317                 int fd = create_and_connect_stream_or_die(opt_connect, 25);
 318                 // make ourselves a simple IO filter
 319                 // from now we know nothing about network :)
 320                 xmove_fd(fd, STDIN_FILENO);
 321                 xdup2(STDIN_FILENO, STDOUT_FILENO);
 322         }
 323
 324 #if ENABLE_FETCHMAIL
 325         // we are sendmail?
 326         if (opt_after_connect)
 327 #endif
 328         {
 329 /***************************************************
 330  * SENDMAIL
 331  ***************************************************/
 332
 333                 char *opt_from;
 334                 int code;
 335                 char *boundary;
 336                 const char *fmt;
 337                 const char *p;
 338                 char *q;
 339
 340                 // we didn't use SSL helper? ->
 341                 if (!(opts & OPT_X)) {
 342                         // ... wait for initial server OK
 343                         smtp_check(NULL, 220);
 344                 }
 345
 346                 // get the sender
 347                 opt_from = sane(*argv++);
 348
 349                 // introduce to server
 350                 // we should start with modern EHLO
 351                 if (250 != smtp_checkp("EHLO %s", opt_from, -1)) {
 352                         smtp_checkp("HELO %s", opt_from, 250);
 353                 }
 354
 355                 // set sender
 356                 // NOTE: if password has not been specified
 357                 // then no authentication is possible
 358                 code = (opts & OPT_P) ? -1 : 250;
 359                 // first try softly without authentication
 360                 while (250 != smtp_checkp("MAIL FROM:<%s>", opt_from, code)) {
 361                         // MAIL FROM failed -> authentication needed
 362                         // have we got username?
 363                         if (!(opts & OPT_U)) {
 364                                 // no! fetch it from "from" option
 365                                 //opts |= OPT_U;
 366                                 opt_user = xstrdup(opt_from);
 367                                 *strchrnul(opt_user, '@') = '\0';
 368                         }
 369                         // now we've got username
 370                         // so try to authenticate
 371                         if (334 == smtp_check("AUTH LOGIN", -1)) {
 372                                 uuencode(NULL, opt_user);
 373                                 smtp_check("", 334);
 374                                 uuencode(NULL, opt_pass);
 375                                 smtp_check("", 235);
 376                         }
 377                         // authenticated OK? -> retry to set sender
 378                         // but this time die on failure!
 379                         code = 250;
 380                 }
 381
 382                 // set recipients
 383                 for (llist_t *to = opt_recipients; to; to = to->link) {
 384                         smtp_checkp("RCPT TO:<%s>", sane(to->data), 250);
 385                 }
 386
 387                 // enter "put message" mode
 388                 smtp_check("DATA", 354);
 389
 390                 // put address headers
 391                 printf("From: %s\r\n", opt_from);
 392                 for (llist_t *to = opt_recipients; to; to = to->link) {
 393                         printf("To: %s\r\n", to->data);
 394                 }
 395
 396                 // put encoded subject
 397                 if (opts & OPTS_c)
 398                         sane((char *)opt_charset);
 399                 if (opts & OPTS_s) {
 400                         printf("Subject: =?%s?B?", opt_charset);
 401                         uuencode(NULL, opt_subject);
 402                         printf("?=\r\n");
 403                 }
 404
 405                 // put notification
 406                 if (opts & OPTS_n)
 407                         printf("Disposition-Notification-To: %s\r\n", opt_from);
 408
 409                 // make a random string -- it will delimit message parts
 410                 srand(monotonic_us());
 411                 boundary = xasprintf("%d-%d-%d", rand(), rand(), rand());
 412
 413                 // put common headers and body start
 414                 printf(
 415                         "Message-ID: <%s>\r\n"
 416                         "Mime-Version: 1.0\r\n"
 417                         "%smultipart/mixed; boundary=\"%s\"\r\n"
 418                         , boundary
 419                         , "Content-Type: "
 420                         , boundary
 421                 );
 422
 423                 // put body + attachment(s)
 424                 // N.B. all these weird things just to be tiny
 425                 // by reusing string patterns!
 426                 fmt =
 427                         "\r\n--%s\r\n"
 428                         "%stext/plain; charset=%s\r\n"
 429                         "%s%s\r\n"
 430                         "%s"
 431                 ;
 432                 p = opt_charset;
 433                 q = (char *)"";
 434                 while (*argv) {
 435                         printf(
 436                                 fmt
 437                                 , boundary
 438                                 , "Content-Type: "
 439                                 , p
 440                                 , "Content-Disposition: inline"
 441                                 , q
 442                                 , "Content-Transfer-Encoding: base64\r\n"
 443                         );
 444                         p = "";
 445                         fmt =
 446                                 "\r\n--%s\r\n"
 447                                 "%sapplication/octet-stream%s\r\n"
 448                                 "%s; filename=\"%s\"\r\n"
 449                                 "%s"
 450                         ;
 451                         uuencode(*argv, NULL);
 452                         if (*(++argv))
 453                                 q = bb_get_last_path_component_strip(*argv);
 454                 }
 455
 456                 // put message terminator
 457                 printf("\r\n--%s--\r\n" "\r\n", boundary);
 458
 459                 // leave "put message" mode
 460                 smtp_check(".", 250);
 461                 // ... and say goodbye
 462                 smtp_check("QUIT", 221);
 463
 464 #if ENABLE_FETCHMAIL
 465         } else {
 466 /***************************************************
 467  * FETCHMAIL
 468  ***************************************************/
 469
 470                 char *buf;
 471                 unsigned nmsg;
 472                 char *hostname;
 473                 pid_t pid;
 474
 475                 // cache fetch command:
 476                 // TOP will return only the headers
 477                 // RETR will dump the whole message
 478                 const char *retr = (opts & OPTF_t) ? "TOP %u 0" : "RETR %u";
 479
 480                 // goto maildir
 481                 xchdir(*argv++);
 482
 483                 // cache postprocess program
 484                 *fargs = *argv;
 485
 486                 // authenticate
 487                 if (!(opts & OPT_U)) {
 488                         //opts |= OPT_U;
 489                         // N.B. IMHO getenv("USER") can be way easily spoofed!
 490                         opt_user = bb_getpwuid(NULL, -1, getuid());
 491                 }
 492
 493                 // get server greeting
 494                 pop3_checkr(NULL, NULL, &buf);
 495
 496                 // server supports APOP?
 497                 if ('<' == *buf) {
 498                         md5_ctx_t md5;
 499                         // yes! compose <stamp><password>
 500                         char *s = strchr(buf, '>');
 501                         if (s)
 502                                 strcpy(s+1, opt_pass);
 503                         s = buf;
 504                         // get md5 sum of <stamp><password>
 505                         md5_begin(&md5);
 506                         md5_hash(s, strlen(s), &md5);
 507                         md5_end(s, &md5);
 508                         // NOTE: md5 struct contains enough space
 509                         // so we reuse md5 space instead of xzalloc(16*2+1)
 510 #define md5_hex ((uint8_t *)&md5)
 511 //                      uint8_t *md5_hex = (uint8_t *)&md5;
 512                         *bin2hex(md5_hex, s, 16) = '\0';
 513                         // APOP
 514                         s = xasprintf("%s %s", opt_user, md5_hex);
 515 #undef md5_hex
 516                         pop3_check("APOP %s", s);
 517                         if (ENABLE_FEATURE_CLEAN_UP) {
 518                                 free(s);
 519                                 free(buf-4); // buf is "+OK " away from malloc'ed string
 520                         }
 521                 // server ignores APOP -> use simple text authentication
 522                 } else {
 523                         // USER
 524                         pop3_check("USER %s", opt_user);
 525                         // PASS
 526                         pop3_check("PASS %s", opt_pass);
 527                 }
 528
 529                 // get mailbox statistics
 530                 pop3_checkr("STAT", NULL, &buf);
 531
 532                 // prepare message filename suffix
 533                 hostname = safe_gethostname();
 534                 pid = getpid();
 535
 536                 // get messages counter
 537                 // NOTE: we don't use xatou(buf) since buf is "nmsg nbytes"
 538                 // we only need nmsg and atoi is just exactly what we need
 539                 // if atoi fails to convert buf into number it returns 0
 540                 // in this case the following loop simply will not be executed
 541                 nmsg = atoi(buf);
 542                 if (ENABLE_FEATURE_CLEAN_UP)
 543                         free(buf-4); // buf is "+OK " away from malloc'ed string
 544
 545                 // loop through messages
 546                 for (; nmsg; nmsg--) {
 547
 548                         // generate unique filename
 549                         char *filename = xasprintf("tmp/%llu.%u.%s", monotonic_us(), pid, hostname);
 550                         char *target;
 551                         int rc;
 552
 553                         // retrieve message in ./tmp/
 554                         pop3_check(retr, (const char *)(ptrdiff_t)nmsg);
 555                         pop3_message(filename);
 556                         // delete message from server
 557                         if (opts & OPTF_z)
 558                                 pop3_check("DELE %u", (const char*)(ptrdiff_t)nmsg);
 559
 560                         // run postprocessing program
 561                         if (*fargs) {
 562                                 fargs[1] = filename;
 563                                 rc = wait4pid(spawn((char **)fargs));
 564                                 if (99 == rc)
 565                                         break;
 566                                 if (1 == rc)
 567                                         goto skip;
 568                         }
 569
 570                         // atomically move message to ./new/
 571                         target = xstrdup(filename);
 572                         strncpy(target, "new", 3);
 573                         // ... or just stop receiving on error
 574                         if (rename_or_warn(filename, target))
 575                                 break;
 576                         free(target);
 577  skip:
 578                         free(filename);
 579                 }
 580
 581                 // Bye
 582                 pop3_check("QUIT", NULL);
 583 #endif // ENABLE_FETCHMAIL
 584         }
 585
 586         return 0;
 587 }