diplodocus.org Git - nmh/blob - uip/popsbr.c

   1 /* popsbr.c -- POP client subroutines
   2  *
   3  * This code is Copyright (c) 2002, by the authors of nmh.  See the
   4  * COPYRIGHT file in the root directory of the nmh distribution for
   5  * complete copyright information.
   6  */
   7
   8 #include "h/mh.h"
   9 #include "sbr/credentials.h"
  10 #include "sbr/client.h"
  11 #include "sbr/error.h"
  12 #include "h/utils.h"
  13 #include "h/oauth.h"
  14 #include "h/netsec.h"
  15
  16 #include "popsbr.h"
  17 #include "h/signals.h"
  18 #include "sbr/base64.h"
  19
  20 #define TRM     "."
  21
  22 static int poprint = 0;
  23
  24 char response[BUFSIZ];
  25 static netsec_context *nsc = NULL;
  26
  27 /*
  28  * static prototypes
  29  */
  30
  31 static int command(const char *, ...) CHECK_PRINTF(1, 2);
  32 static int multiline(void);
  33
  34 static int traverse(int (*)(void *, char *), void *closure,
  35     const char *, ...) CHECK_PRINTF(3, 4);
  36 static int vcommand(const char *, va_list) CHECK_PRINTF(1, 0);
  37 static int pop_getline (char *, int, netsec_context *);
  38 static int pop_sasl_callback(enum sasl_message_type, unsigned const char *,
  39                              unsigned int, unsigned char **, unsigned int *,
  40                              void *, char **);
  41
  42 static int
  43 check_mech(char *server_mechs, size_t server_mechs_size)
  44 {
  45   int status;
  46   bool sasl_capability = false;
  47
  48     /*
  49      * First off, we're going to send the CAPA command to see if we can
  50      * even support the AUTH command, and if we do, then we'll get a
  51      * list of mechanisms the server supports.  If we don't support
  52      * the CAPA command, then it's unlikely that we will support
  53      * SASL
  54      */
  55
  56     if (command("CAPA") == NOTOK) {
  57         snprintf(response, sizeof(response),
  58                  "The POP CAPA command failed; POP server does not "
  59                  "support SASL");
  60         return NOTOK;
  61     }
  62
  63     while ((status = multiline()) != DONE) {
  64         if (status == NOTOK)
  65             return NOTOK;
  66
  67         if (strncasecmp(response, "SASL ", 5) == 0) {
  68             /* We've seen the SASL capability.  Grab the mech list. */
  69             sasl_capability = true;
  70             strncpy(server_mechs, response + 5, server_mechs_size);
  71         }
  72     }
  73
  74     if (!sasl_capability) {
  75         snprintf(response, sizeof(response), "POP server does not support "
  76                  "SASL");
  77         return NOTOK;
  78     }
  79
  80     return OK;
  81 }
  82
  83 /*
  84  * If capable, issue the STLS command and start the TLS negotiation
  85  */
  86
  87 static int
  88 pop_start_tls(void)
  89 {
  90     int status;
  91     bool stls = false;
  92     char *errstr;
  93
  94     /*
  95      * Issue the CAPA command and see if we have the STLS capability
  96      */
  97
  98     if (command("CAPA") == NOTOK) {
  99         snprintf(response, sizeof(response),
 100                  "The POP CAPA command failed; POP server does not "
 101                  "support STLS");
 102         return NOTOK;
 103     }
 104
 105     while ((status = multiline()) != DONE) {
 106         if (status == NOTOK)
 107             return NOTOK;
 108
 109         if (strcasecmp(response, "STLS") == 0)
 110             stls = true;
 111     }
 112
 113     if (!stls) {
 114         snprintf(response, sizeof(response), "POP server does not support "
 115                  "STLS");
 116         return NOTOK;
 117     }
 118
 119     /*
 120      * Issue STLS and then start the actual TLS negotiation
 121      */
 122
 123     if (command("STLS") == NOTOK)
 124         return NOTOK;
 125
 126     if (netsec_negotiate_tls(nsc, &errstr) != OK) {
 127         snprintf(response, sizeof(response), "%s", errstr);
 128         free(errstr);
 129         return NOTOK;
 130     }
 131
 132     return OK;
 133 }
 134
 135 /*
 136  * Split string containing proxy command into an array of arguments
 137  * suitable for passing to exec. Returned array must be freed. Shouldn't
 138  * be possible to call this with host set to NULL.
 139  */
 140 static char **
 141 parse_proxy(char *proxy, char *host)
 142 {
 143     char **pargv, **p;
 144     int pargc = 2;
 145     int hlen = strlen(host);
 146     int plen = 1;
 147     unsigned char *cur, *pro;
 148     char *c;
 149
 150     /* skip any initial space */
 151     for (pro = (unsigned char *) proxy; isspace(*pro); pro++)
 152         continue;
 153
 154     /* calculate required size for argument array */
 155     for (cur = pro; *cur; cur++) {
 156         if (isspace(*cur) && cur[1] && !isspace(cur[1]))
 157             plen++, pargc++;
 158         else if (*cur == '%' && cur[1] == 'h') {
 159             plen += hlen;
 160             cur++;
 161         } else if (!isspace(*cur))
 162             plen++;
 163     }
 164
 165    /* put together list of arguments */
 166     p = pargv = mh_xmalloc(pargc * sizeof(char *));
 167     c = *pargv = mh_xmalloc(plen);
 168     for (cur = pro; *cur; cur++) {
 169         if (isspace(*cur) && cur[1] && !isspace(cur[1])) {
 170             *c++ = '\0';
 171             *++p = c;
 172         } else if (*cur == '%' && cur[1] == 'h') {
 173             strcpy (c, host);
 174             c += hlen;
 175             cur++;
 176         } else if (!isspace(*cur))
 177             *c++ = *cur;
 178     }
 179     *c = '\0';
 180     *++p = NULL;
 181     return pargv;
 182 }
 183
 184 int
 185 pop_init (char *host, char *port, char *user, char *proxy, int snoop,
 186           int sasl, char *mech, int tls, const char *oauth_svc)
 187 {
 188     int fd1, fd2;
 189     char buffer[BUFSIZ];
 190     char *errstr;
 191
 192     nsc = netsec_init();
 193
 194     if (user)
 195         netsec_set_userid(nsc, user);
 196
 197     netsec_set_hostname(nsc, host);
 198
 199     if (oauth_svc != NULL) {
 200         if (netsec_set_oauth_service(nsc, oauth_svc) != OK) {
 201             snprintf(response, sizeof(response), "OAuth2 not supported");
 202             return NOTOK;
 203         }
 204     }
 205
 206     if (proxy && *proxy) {
 207        int pid;
 208        int inpipe[2];     /* for reading from the server */
 209        int outpipe[2];    /* for sending to the server */
 210
 211        if (pipe(inpipe) < 0) {
 212            adios ("inpipe", "pipe");
 213        }
 214        if (pipe(outpipe) < 0) {
 215            adios ("outpipe", "pipe");
 216        }
 217
 218        pid=fork();
 219        if (pid==0) {
 220            char **argv;
 221
 222            /* in child */
 223            close(0);
 224            close(1);
 225            dup2(outpipe[0],0);  /* connect read end of connection */
 226            dup2(inpipe[1], 1);  /* connect write end of connection */
 227            if(inpipe[0]>1) close(inpipe[0]);
 228            if(inpipe[1]>1) close(inpipe[1]);
 229            if(outpipe[0]>1) close(outpipe[0]);
 230            if(outpipe[1]>1) close(outpipe[1]);
 231
 232            /* run the proxy command */
 233            argv=parse_proxy(proxy, host);
 234            execvp(argv[0],argv);
 235
 236            perror(argv[0]);
 237            close(0);
 238            close(1);
 239            free(*argv);
 240            free(argv);
 241            exit(1);
 242        }
 243
 244        /* okay in the parent we do some stuff */
 245        close(inpipe[1]);  /* child uses this */
 246        close(outpipe[0]); /* child uses this */
 247
 248        /* we read on fd1 */
 249        fd1=inpipe[0];
 250        /* and write on fd2 */
 251        fd2=outpipe[1];
 252
 253     } else {
 254         if ((fd1 = client (host, port ? port : "pop3", response,
 255                            sizeof(response), snoop)) == NOTOK) {
 256             return NOTOK;
 257         }
 258         fd2 = fd1;
 259     }
 260
 261     SIGNAL (SIGPIPE, SIG_IGN);
 262
 263     netsec_set_fd(nsc, fd1, fd2);
 264     netsec_set_snoop(nsc, snoop);
 265
 266     if (tls & P_TLSENABLEMASK) {
 267         if (netsec_set_tls(nsc, 1, tls & P_NOVERIFY, &errstr) != OK) {
 268             snprintf(response, sizeof(response), "%s", errstr);
 269             free(errstr);
 270             return NOTOK;
 271         }
 272
 273         if (tls & P_INITTLS) {
 274             if (netsec_negotiate_tls(nsc, &errstr) != OK) {
 275                 snprintf(response, sizeof(response), "%s", errstr);
 276                 free(errstr);
 277                 return NOTOK;
 278             }
 279         }
 280     }
 281
 282     if (sasl) {
 283         if (netsec_set_sasl_params(nsc, "pop", mech, pop_sasl_callback,
 284                                    NULL, &errstr) != OK) {
 285             snprintf(response, sizeof(response), "%s", errstr);
 286             free(errstr);
 287             return NOTOK;
 288         }
 289     }
 290
 291     switch (pop_getline (response, sizeof response, nsc)) {
 292         case OK:
 293             if (poprint)
 294                 fprintf (stderr, "<--- %s\n", response);
 295             if (*response == '+') {
 296                 nmh_creds_t creds;
 297
 298                 if (tls & P_STARTTLS)
 299                     if (pop_start_tls() != OK)
 300                         return NOTOK;
 301
 302                 if (sasl) {
 303                     char server_mechs[256];
 304                     if (check_mech(server_mechs, sizeof(server_mechs)) != OK)
 305                         return NOTOK;
 306                     if (netsec_negotiate_sasl(nsc, server_mechs,
 307                                               &errstr) != OK) {
 308                         strncpy(response, errstr, sizeof(response));
 309                         response[sizeof(response) - 1] = '\0';
 310                         free(errstr);
 311                         return NOTOK;
 312                     }
 313                     return OK;
 314                 }
 315
 316                 if (!(creds = nmh_get_credentials(host, user)))
 317                     return NOTOK;
 318                 if (command ("USER %s", nmh_cred_get_user(creds))
 319                                                             != NOTOK) {
 320                     if (command("PASS %s", nmh_cred_get_password(creds))
 321                                                             != NOTOK) {
 322                         nmh_credentials_free(creds);
 323                         return OK;
 324                     }
 325                 }
 326                 nmh_credentials_free(creds);
 327             }
 328             strncpy (buffer, response, sizeof(buffer));
 329             command ("QUIT");
 330             strncpy (response, buffer, sizeof(response));
 331             /* FALLTHRU */
 332
 333         case NOTOK:
 334         case DONE:
 335             if (poprint) {
 336                 fputs(response, stderr);
 337                 putc('\n', stderr);
 338             }
 339             netsec_shutdown(nsc);
 340             nsc = NULL;
 341             return NOTOK;
 342     }
 343
 344     return NOTOK;       /* NOTREACHED */
 345 }
 346
 347
 348 /*
 349  * Our SASL callback; we are given SASL tokens and then have to format
 350  * them according to the protocol requirements, and then process incoming
 351  * messages and feed them back into the SASL library.
 352  */
 353
 354 static int
 355 pop_sasl_callback(enum sasl_message_type mtype, unsigned const char *indata,
 356                   unsigned int indatalen, unsigned char **outdata,
 357                   unsigned int *outdatalen, void *context, char **errstr)
 358 {
 359     int rc, snoopoffset;
 360     char *mech, *line;
 361     size_t len, b64len;
 362     NMH_UNUSED(context);
 363
 364     switch (mtype) {
 365     case NETSEC_SASL_START:
 366         /*
 367          * Generate our AUTH message, but there is a wrinkle.
 368          *
 369          * Technically, according to RFC 5034, if your command INCLUDING
 370          * an initial response exceeds 255 octets (including CRLF), you
 371          * can't issue this all in one go, but have to just issue the
 372          * AUTH command, wait for a blank initial response, and then
 373          * send your data.
 374          */
 375
 376         mech = netsec_get_sasl_mechanism(nsc);
 377
 378         if (indatalen) {
 379             char *b64data;
 380             b64data = mh_xmalloc(BASE64SIZE(indatalen));
 381             writeBase64raw(indata, indatalen, (unsigned char *) b64data);
 382             b64len = strlen(b64data);
 383
 384             /* Formula here is AUTH + SP + mech + SP + out + CR + LF */
 385             len = b64len + 8 + strlen(mech);
 386             if (len > 255) {
 387                 rc = netsec_printf(nsc, errstr, "AUTH %s\r\n", mech);
 388                 if (rc)
 389                     return NOTOK;
 390                 if (netsec_flush(nsc, errstr) != OK)
 391                     return NOTOK;
 392                 line = netsec_readline(nsc, &len, errstr);
 393                 if (! line)
 394                     return NOTOK;
 395                 /*
 396                  * If the protocol is being followed correctly, should just
 397                  * be a "+ ", nothing else.
 398                  */
 399                 if (len != 2 || strcmp(line, "+ ") != 0) {
 400                     netsec_err(errstr, "Did not get expected blank response "
 401                                "for initial challenge response");
 402                     return NOTOK;
 403                 }
 404                 rc = netsec_printf(nsc, errstr, "%s\r\n", b64data);
 405                 free(b64data);
 406                 if (rc != OK)
 407                     return NOTOK;
 408                 netsec_set_snoop_callback(nsc, netsec_b64_snoop_decoder, NULL);
 409                 rc = netsec_flush(nsc, errstr);
 410                 netsec_set_snoop_callback(nsc, NULL, NULL);
 411                 if (rc != OK)
 412                     return NOTOK;
 413             } else {
 414                 rc = netsec_printf(nsc, errstr, "AUTH %s %s\r\n", mech,
 415                                    b64data);
 416                 free(b64data);
 417                 if (rc != OK)
 418                     return NOTOK;
 419                 netsec_set_snoop_callback(nsc, netsec_b64_snoop_decoder,
 420                                           &snoopoffset);
 421                 snoopoffset = 6 + strlen(mech);
 422                 rc = netsec_flush(nsc, errstr);
 423                 netsec_set_snoop_callback(nsc, NULL, NULL);
 424                 if (rc != OK)
 425                     return NOTOK;
 426             }
 427         } else {
 428             if (netsec_printf(nsc, errstr, "AUTH %s\r\n", mech) != OK)
 429                 return NOTOK;
 430             if (netsec_flush(nsc, errstr) != OK)
 431                 return NOTOK;
 432         }
 433
 434         break;
 435
 436         /*
 437          * We should get one line back, with our base64 data.  Decode that
 438          * and feed it back into the SASL library.
 439          */
 440     case NETSEC_SASL_READ:
 441         netsec_set_snoop_callback(nsc, netsec_b64_snoop_decoder, &snoopoffset);
 442         snoopoffset = 2;
 443         line = netsec_readline(nsc, &len, errstr);
 444         netsec_set_snoop_callback(nsc, NULL, NULL);
 445
 446         if (line == NULL)
 447             return NOTOK;
 448         if (len < 2 || (len == 2 && strcmp(line, "+ ") != 0)) {
 449             netsec_err(errstr, "Invalid format for SASL response");
 450             return NOTOK;
 451         }
 452
 453         if (len == 2) {
 454             *outdata = NULL;
 455             *outdatalen = 0;
 456         } else {
 457             rc = decodeBase64(line + 2, outdata, &len, 0);
 458             *outdatalen = len;
 459             if (rc != OK) {
 460                 netsec_err(errstr, "Unable to decode base64 response");
 461                 return NOTOK;
 462             }
 463         }
 464         break;
 465
 466     /*
 467      * Our encoding is pretty simple, so this is easy.
 468      */
 469
 470     case NETSEC_SASL_WRITE:
 471         if (indatalen == 0) {
 472             rc = netsec_printf(nsc, errstr, "\r\n");
 473         } else {
 474             unsigned char *b64data;
 475             b64data = mh_xmalloc(BASE64SIZE(indatalen));
 476             writeBase64raw(indata, indatalen, b64data);
 477             rc = netsec_printf(nsc, errstr, "%s\r\n", b64data);
 478             free(b64data);
 479         }
 480
 481         if (rc != OK)
 482             return NOTOK;
 483
 484         if (indatalen > 0)
 485             netsec_set_snoop_callback(nsc, netsec_b64_snoop_decoder, NULL);
 486         rc = netsec_flush(nsc, errstr);
 487         netsec_set_snoop_callback(nsc, NULL, NULL);
 488         if (rc != OK)
 489             return NOTOK;
 490         break;
 491
 492     /*
 493      * Finish the protocol; we're looking for an +OK
 494      */
 495
 496     case NETSEC_SASL_FINISH:
 497         line = netsec_readline(nsc, &len, errstr);
 498         if (line == NULL)
 499             return NOTOK;
 500
 501         if (!has_prefix(line, "+OK")) {
 502             netsec_err(errstr, "Authentication failed: %s", line);
 503             return NOTOK;
 504         }
 505         break;
 506
 507     /*
 508      * Cancel the SASL exchange in the middle of the commands; for
 509      * POP, that's a single "*".
 510      *
 511      * It's unclear to me if I should be returning errors up; I finally
 512      * decided the answer should be "yes", and if the upper layer wants to
 513      * ignore them that's their choice.
 514      */
 515
 516     case NETSEC_SASL_CANCEL:
 517         rc = netsec_printf(nsc, errstr, "*\r\n");
 518         if (rc == OK)
 519             rc = netsec_flush(nsc, errstr);
 520         if (rc != OK)
 521             return NOTOK;
 522         break;
 523     }
 524
 525     return OK;
 526 }
 527
 528 /*
 529  * Find out number of messages available
 530  * and their total size.
 531  */
 532
 533 int
 534 pop_stat (int *nmsgs, int *nbytes)
 535 {
 536
 537     if (command ("STAT") == NOTOK)
 538         return NOTOK;
 539
 540     *nmsgs = *nbytes = 0;
 541     sscanf (response, "+OK %d %d", nmsgs, nbytes);
 542
 543     return OK;
 544 }
 545
 546
 547 int
 548 pop_retr (int msgno, int (*action)(void *, char *), void *closure)
 549 {
 550     return traverse (action, closure, "RETR %d", msgno);
 551 }
 552
 553
 554 static int
 555 traverse (int (*action)(void *, char *), void *closure, const char *fmt, ...)
 556 {
 557     int result, snoopstate;
 558     va_list ap;
 559     char buffer[sizeof(response)];
 560
 561     va_start(ap, fmt);
 562     result = vcommand (fmt, ap);
 563     va_end(ap);
 564
 565     if (result == NOTOK)
 566         return NOTOK;
 567     strncpy (buffer, response, sizeof(buffer));
 568
 569     if ((snoopstate = netsec_get_snoop(nsc)))
 570         netsec_set_snoop(nsc, 0);
 571
 572     for (;;) {
 573         result = multiline();
 574         if (result == OK) {
 575             result = (*action)(closure, response);
 576             if (result == OK)
 577                 continue;
 578         } else if (result == DONE) {
 579             strncpy(response, buffer, sizeof(response));
 580             result = OK;
 581         }
 582         break;
 583     }
 584
 585     netsec_set_snoop(nsc, snoopstate);
 586     return result;
 587 }
 588
 589
 590 int
 591 pop_dele (int msgno)
 592 {
 593     return command ("DELE %d", msgno);
 594 }
 595
 596
 597 int
 598 pop_quit (void)
 599 {
 600     int i;
 601
 602     i = command ("QUIT");
 603     pop_done ();
 604
 605     return i;
 606 }
 607
 608
 609 int
 610 pop_done (void)
 611 {
 612     if (nsc)
 613         netsec_shutdown(nsc);
 614
 615     return OK;
 616 }
 617
 618
 619 static int
 620 command(const char *fmt, ...)
 621 {
 622     va_list ap;
 623     int result;
 624
 625     va_start(ap, fmt);
 626     result = vcommand(fmt, ap);
 627     va_end(ap);
 628
 629     return result;
 630 }
 631
 632
 633 static int
 634 vcommand (const char *fmt, va_list ap)
 635 {
 636     /* char *cp; */
 637     char *errstr;
 638
 639     if (netsec_vprintf(nsc, &errstr, fmt, ap) != OK) {
 640         strncpy(response, errstr, sizeof(response));
 641         response[sizeof(response) - 1] = '\0';
 642         free(errstr);
 643         return NOTOK;
 644     }
 645
 646     if (netsec_printf(nsc, &errstr, "\r\n") != OK) {
 647         strncpy(response, errstr, sizeof(response));
 648         response[sizeof(response) - 1] = '\0';
 649         free(errstr);
 650         return NOTOK;
 651     }
 652
 653     if (netsec_flush(nsc, &errstr) != OK) {
 654         strncpy(response, errstr, sizeof(response));
 655         response[sizeof(response) - 1] = '\0';
 656         free(errstr);
 657         return NOTOK;
 658     }
 659
 660     switch (pop_getline (response, sizeof response, nsc)) {
 661         case OK:
 662             if (poprint)
 663                 fprintf (stderr, "<--- %s\n", response);
 664             return *response == '+' ? OK : NOTOK;
 665
 666         case NOTOK:
 667         case DONE:
 668             if (poprint) {
 669                 fputs(response, stderr);
 670                 putc('\n', stderr);
 671             }
 672             return NOTOK;
 673     }
 674
 675     return NOTOK;       /* NOTREACHED */
 676 }
 677
 678
 679 static int
 680 multiline (void)
 681 {
 682     char buffer[BUFSIZ + LEN(TRM)];
 683
 684     if (pop_getline (buffer, sizeof buffer, nsc) != OK)
 685         return NOTOK;
 686     if (has_prefix(buffer, TRM)) {
 687         if (buffer[LEN(TRM)] == 0)
 688             return DONE;
 689         strncpy (response, buffer + LEN(TRM), sizeof(response));
 690     }
 691     else
 692         strncpy (response, buffer, sizeof(response));
 693
 694     return OK;
 695 }
 696
 697 /*
 698  * This is now just a thin wrapper around netsec_readline().
 699  */
 700
 701 static int
 702 pop_getline (char *s, int n, netsec_context *ns)
 703 {
 704     /* int c = -2; */
 705     char *p;
 706     size_t len, destlen;
 707     /* int rc; */
 708     char *errstr;
 709
 710     p = netsec_readline(ns, &len, &errstr);
 711
 712     if (p == NULL) {
 713         strncpy(response, errstr, sizeof(response));
 714         response[sizeof(response) - 1] = '\0';
 715         free(errstr);
 716         return NOTOK;
 717     }
 718
 719     /*
 720      * If we had an error, it should have been returned already.  Since
 721      * netsec_readline() strips off the CR-LF ending, just copy the existing
 722      * buffer into response now.
 723      *
 724      * We get a length back from netsec_readline, but the rest of the POP
 725      * code doesn't handle it; the assumptions are that everything from
 726      * the network can be represented as C strings.  That should get fixed
 727      * someday.
 728      */
 729
 730     destlen = min(len, (size_t)(n - 1));
 731
 732     memcpy(s, p, destlen);
 733     s[destlen] = '\0';
 734
 735     return OK;
 736 }