lib-src/pop.c

   1 /* pop.c: client routines for talking to a POP3-protocol post-office server
   2    Copyright (c) 1991, 1993, 1996 Free Software Foundation, Inc.
   3    Written by Jonathan Kamens, jik@security.ov.com.
   4
   5 This file is part of GNU Emacs.
   6
   7 GNU Emacs is free software; you can redistribute it and/or modify
   8 it under the terms of the GNU General Public License as published by
   9 the Free Software Foundation; either version 2, or (at your option)
  10 any later version.
  11
  12 GNU Emacs is distributed in the hope that it will be useful,
  13 but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 GNU General Public License for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GNU Emacs; see the file COPYING.  If not, write to
  19 the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  20 Boston, MA 02111-1307, USA.  */
  21
  22 #ifdef HAVE_CONFIG_H
  23 #define NO_SHORTNAMES   /* Tell config not to load remap.h */
  24 #include <../src/config.h>
  25 #else
  26 #define MAIL_USE_POP
  27 #endif
  28
  29 #ifdef MAIL_USE_POP
  30
  31 #ifdef HAVE_CONFIG_H
  32 /* Cancel these substitutions made in config.h */
  33 #undef open
  34 #undef read
  35 #undef write
  36 #undef close
  37 #endif
  38
  39 #include <sys/types.h>
  40 #ifdef WINDOWSNT
  41 #include "ntlib.h"
  42 #include <winsock.h>
  43 #undef SOCKET_ERROR
  44 #define RECV(s,buf,len,flags) recv(s,buf,len,flags)
  45 #define SEND(s,buf,len,flags) send(s,buf,len,flags)
  46 #define CLOSESOCKET(s) closesocket(s)
  47 #else
  48 #include <netinet/in.h>
  49 #include <sys/socket.h>
  50 #define RECV(s,buf,len,flags) read(s,buf,len)
  51 #define SEND(s,buf,len,flags) write(s,buf,len)
  52 #define CLOSESOCKET(s) close(s)
  53 #endif
  54 #include <pop.h>
  55
  56 #ifdef sun
  57 #include <malloc.h>
  58 #endif /* sun */
  59
  60 #ifdef HESIOD
  61 #include <hesiod.h>
  62 /*
  63  * It really shouldn't be necessary to put this declaration here, but
  64  * the version of hesiod.h that Athena has installed in release 7.2
  65  * doesn't declare this function; I don't know if the 7.3 version of
  66  * hesiod.h does.
  67  */
  68 extern struct servent *hes_getservbyname (/* char *, char * */);
  69 #endif
  70
  71 #include <pwd.h>
  72 #include <netdb.h>
  73 #include <errno.h>
  74 #include <stdio.h>
  75
  76 #ifdef KERBEROS
  77 #ifndef KRB5
  78 #ifndef SOLARIS2
  79 #include <des.h>
  80 #include <krb.h>
  81 #else /* not SOLARIS2 */
  82 #include <kerberos/des.h>
  83 #include <kerberos/krb.h>
  84 #endif /* not SOLARIS2 */
  85 #else /* KRB5 */
  86 #include <krb5/krb5.h>
  87 #include <krb5/ext-proto.h>
  88 #include <ctype.h>
  89 #endif /* KRB5 */
  90 #endif /* KERBEROS */
  91
  92 extern char *getenv (/* char * */);
  93 extern char *getlogin (/* void */);
  94 extern char *getpass (/* char * */);
  95 extern char *strerror (/* int */);
  96 extern char *index ();
  97
  98 #ifdef KERBEROS
  99 #ifndef KRB5
 100 extern int krb_sendauth (/* long, int, KTEXT, char *, char *, char *,
 101                             u_long, MSG_DAT *, CREDENTIALS *, Key_schedule,
 102                             struct sockaddr_in *, struct sockaddr_in *,
 103                             char * */);
 104 extern char *krb_realmofhost (/* char * */);
 105 #endif /* ! KRB5 */
 106 #endif /* KERBEROS */
 107
 108 #ifndef WINDOWSNT
 109 #if !defined(HAVE_H_ERRNO) || !defined(HAVE_CONFIG_H)
 110 extern int h_errno;
 111 #endif
 112 #endif
 113
 114 static int socket_connection (/* char *, int */);
 115 static char *getline (/* popserver */);
 116 static int sendline (/* popserver, char * */);
 117 static int fullwrite (/* int, char *, int */);
 118 static int getok (/* popserver */);
 119 #if 0
 120 static int gettermination (/* popserver */);
 121 #endif
 122 static void pop_trash (/* popserver */);
 123 static char *find_crlf (/* char * */);
 124
 125 #define ERROR_MAX 80            /* a pretty arbitrary size */
 126 #define POP_PORT 110
 127 #define KPOP_PORT 1109
 128 #ifdef WINDOWSNT
 129 #define POP_SERVICE "pop3"      /* we don't want the POP2 port! */
 130 #else
 131 #define POP_SERVICE "pop"
 132 #endif
 133 #ifdef KERBEROS
 134 #ifdef KRB5
 135 #define KPOP_SERVICE "k5pop";
 136 #else
 137 #define KPOP_SERVICE "kpop"
 138 #endif
 139 #endif
 140
 141 char pop_error[ERROR_MAX];
 142 int pop_debug = 0;
 143
 144 #ifndef min
 145 #define min(a,b) (((a) < (b)) ? (a) : (b))
 146 #endif
 147
 148 /*
 149  * Function: pop_open (char *host, char *username, char *password,
 150  *                     int flags)
 151  *
 152  * Purpose: Establishes a connection with a post-office server, and
 153  *      completes the authorization portion of the session.
 154  *
 155  * Arguments:
 156  *      host    The server host with which the connection should be
 157  *              established.  Optional.  If omitted, internal
 158  *              heuristics will be used to determine the server host,
 159  *              if possible.
 160  *      username
 161  *              The username of the mail-drop to access.  Optional.
 162  *              If omitted, internal heuristics will be used to
 163  *              determine the username, if possible.
 164  *      password
 165  *              The password to use for authorization.  If omitted,
 166  *              internal heuristics will be used to determine the
 167  *              password, if possible.
 168  *      flags   A bit mask containing flags controlling certain
 169  *              functions of the routine.  Valid flags are defined in
 170  *              the file pop.h
 171  *
 172  * Return value: Upon successful establishment of a connection, a
 173  *      non-null popserver will be returned.  Otherwise, null will be
 174  *      returned, and the string variable pop_error will contain an
 175  *      explanation of the error.
 176  */
 177 popserver
 178 pop_open (host, username, password, flags)
 179      char *host;
 180      char *username;
 181      char *password;
 182      int flags;
 183 {
 184   int sock;
 185   popserver server;
 186
 187   /* Determine the user name */
 188   if (! username)
 189     {
 190       username = getenv ("USER");
 191       if (! (username && *username))
 192         {
 193           username = getlogin ();
 194           if (! (username && *username))
 195             {
 196               struct passwd *passwd;
 197               passwd = getpwuid (getuid ());
 198               if (passwd && passwd->pw_name && *passwd->pw_name)
 199                 {
 200                   username = passwd->pw_name;
 201                 }
 202               else
 203                 {
 204                   strcpy (pop_error, "Could not determine username");
 205                   return (0);
 206                 }
 207             }
 208         }
 209     }
 210
 211   /*
 212    *  Determine the mail host.
 213    */
 214
 215   if (! host)
 216     {
 217       host = getenv ("MAILHOST");
 218     }
 219
 220 #ifdef HESIOD
 221   if ((! host) && (! (flags & POP_NO_HESIOD)))
 222     {
 223       struct hes_postoffice *office;
 224       office = hes_getmailhost (username);
 225       if (office && office->po_type && (! strcmp (office->po_type, "POP"))
 226           && office->po_name && *office->po_name && office->po_host
 227           && *office->po_host)
 228         {
 229           host = office->po_host;
 230           username = office->po_name;
 231         }
 232     }
 233 #endif
 234
 235 #ifdef MAILHOST
 236   if (! host)
 237     {
 238       host = MAILHOST;
 239     }
 240 #endif
 241
 242   if (! host)
 243     {
 244       strcpy (pop_error, "Could not determine POP server");
 245       return (0);
 246     }
 247
 248   /* Determine the password */
 249 #ifdef KERBEROS
 250 #define DONT_NEED_PASSWORD (! (flags & POP_NO_KERBEROS))
 251 #else
 252 #define DONT_NEED_PASSWORD 0
 253 #endif
 254
 255   if ((! password) && (! DONT_NEED_PASSWORD))
 256     {
 257       if (! (flags & POP_NO_GETPASS))
 258         {
 259           password = getpass ("Enter POP password:");
 260         }
 261       if (! password)
 262         {
 263           strcpy (pop_error, "Could not determine POP password");
 264           return (0);
 265         }
 266     }
 267   if (password)
 268     flags |= POP_NO_KERBEROS;
 269   else
 270     password = username;
 271
 272   sock = socket_connection (host, flags);
 273   if (sock == -1)
 274     return (0);
 275
 276   server = (popserver) malloc (sizeof (struct _popserver));
 277   if (! server)
 278     {
 279       strcpy (pop_error, "Out of memory in pop_open");
 280       return (0);
 281     }
 282   server->buffer = (char *) malloc (GETLINE_MIN);
 283   if (! server->buffer)
 284     {
 285       strcpy (pop_error, "Out of memory in pop_open");
 286       free ((char *) server);
 287       return (0);
 288     }
 289
 290   server->file = sock;
 291   server->data = 0;
 292   server->buffer_index = 0;
 293   server->buffer_size = GETLINE_MIN;
 294   server->in_multi = 0;
 295   server->trash_started = 0;
 296
 297   if (getok (server))
 298     return (0);
 299
 300   /*
 301    * I really shouldn't use the pop_error variable like this, but....
 302    */
 303   if (strlen (username) > ERROR_MAX - 6)
 304     {
 305       pop_close (server);
 306       strcpy (pop_error,
 307               "Username too long; recompile pop.c with larger ERROR_MAX");
 308       return (0);
 309     }
 310   sprintf (pop_error, "USER %s", username);
 311
 312   if (sendline (server, pop_error) || getok (server))
 313     {
 314       return (0);
 315     }
 316
 317   if (strlen (password) > ERROR_MAX - 6)
 318     {
 319       pop_close (server);
 320       strcpy (pop_error,
 321               "Password too long; recompile pop.c with larger ERROR_MAX");
 322       return (0);
 323     }
 324   sprintf (pop_error, "PASS %s", password);
 325
 326   if (sendline (server, pop_error) || getok (server))
 327     {
 328       return (0);
 329     }
 330
 331   return (server);
 332 }
 333
 334 /*
 335  * Function: pop_stat
 336  *
 337  * Purpose: Issue the STAT command to the server and return (in the
 338  *      value parameters) the number of messages in the maildrop and
 339  *      the total size of the maildrop.
 340  *
 341  * Return value: 0 on success, or non-zero with an error in pop_error
 342  *      in failure.
 343  *
 344  * Side effects: On failure, may make further operations on the
 345  *      connection impossible.
 346  */
 347 int
 348 pop_stat (server, count, size)
 349      popserver server;
 350      int *count;
 351      int *size;
 352 {
 353   char *fromserver;
 354
 355   if (server->in_multi)
 356     {
 357       strcpy (pop_error, "In multi-line query in pop_stat");
 358       return (-1);
 359     }
 360
 361   if (sendline (server, "STAT") || (! (fromserver = getline (server))))
 362     return (-1);
 363
 364   if (strncmp (fromserver, "+OK ", 4))
 365     {
 366       if (0 == strncmp (fromserver, "-ERR", 4))
 367         {
 368           strncpy (pop_error, fromserver, ERROR_MAX);
 369         }
 370       else
 371         {
 372           strcpy (pop_error,
 373                   "Unexpected response from POP server in pop_stat");
 374           pop_trash (server);
 375         }
 376       return (-1);
 377     }
 378
 379   *count = atoi (&fromserver[4]);
 380
 381   fromserver = index (&fromserver[4], ' ');
 382   if (! fromserver)
 383     {
 384       strcpy (pop_error,
 385               "Badly formatted response from server in pop_stat");
 386       pop_trash (server);
 387       return (-1);
 388     }
 389
 390   *size = atoi (fromserver + 1);
 391
 392   return (0);
 393 }
 394
 395 /*
 396  * Function: pop_list
 397  *
 398  * Purpose: Performs the POP "list" command and returns (in value
 399  *      parameters) two malloc'd zero-terminated arrays -- one of
 400  *      message IDs, and a parallel one of sizes.
 401  *
 402  * Arguments:
 403  *      server  The pop connection to talk to.
 404  *      message The number of the one message about which to get
 405  *              information, or 0 to get information about all
 406  *              messages.
 407  *
 408  * Return value: 0 on success, non-zero with error in pop_error on
 409  *      failure.
 410  *
 411  * Side effects: On failure, may make further operations on the
 412  *      connection impossible.
 413  */
 414 int
 415 pop_list (server, message, IDs, sizes)
 416      popserver server;
 417      int message;
 418      int **IDs;
 419      int **sizes;
 420 {
 421   int how_many, i;
 422   char *fromserver;
 423
 424   if (server->in_multi)
 425     {
 426       strcpy (pop_error, "In multi-line query in pop_list");
 427       return (-1);
 428     }
 429
 430   if (message)
 431     how_many = 1;
 432   else
 433     {
 434       int count, size;
 435       if (pop_stat (server, &count, &size))
 436         return (-1);
 437       how_many = count;
 438     }
 439
 440   *IDs = (int *) malloc ((how_many + 1) * sizeof (int));
 441   *sizes = (int *) malloc ((how_many + 1) * sizeof (int));
 442   if (! (*IDs && *sizes))
 443     {
 444       strcpy (pop_error, "Out of memory in pop_list");
 445       return (-1);
 446     }
 447
 448   if (message)
 449     {
 450       sprintf (pop_error, "LIST %d", message);
 451       if (sendline (server, pop_error))
 452         {
 453           free ((char *) *IDs);
 454           free ((char *) *sizes);
 455           return (-1);
 456         }
 457       if (! (fromserver = getline (server)))
 458         {
 459           free ((char *) *IDs);
 460           free ((char *) *sizes);
 461           return (-1);
 462         }
 463       if (strncmp (fromserver, "+OK ", 4))
 464         {
 465           if (! strncmp (fromserver, "-ERR", 4))
 466             strncpy (pop_error, fromserver, ERROR_MAX);
 467           else
 468             {
 469               strcpy (pop_error,
 470                       "Unexpected response from server in pop_list");
 471               pop_trash (server);
 472             }
 473           free ((char *) *IDs);
 474           free ((char *) *sizes);
 475           return (-1);
 476         }
 477       (*IDs)[0] = atoi (&fromserver[4]);
 478       fromserver = index (&fromserver[4], ' ');
 479       if (! fromserver)
 480         {
 481           strcpy (pop_error,
 482                   "Badly formatted response from server in pop_list");
 483           pop_trash (server);
 484           free ((char *) *IDs);
 485           free ((char *) *sizes);
 486           return (-1);
 487         }
 488       (*sizes)[0] = atoi (fromserver);
 489       (*IDs)[1] = (*sizes)[1] = 0;
 490       return (0);
 491     }
 492   else
 493     {
 494       if (pop_multi_first (server, "LIST", &fromserver))
 495         {
 496           free ((char *) *IDs);
 497           free ((char *) *sizes);
 498           return (-1);
 499         }
 500       for (i = 0; i < how_many; i++)
 501         {
 502           if (pop_multi_next (server, &fromserver))
 503             {
 504               free ((char *) *IDs);
 505               free ((char *) *sizes);
 506               return (-1);
 507             }
 508           (*IDs)[i] = atoi (fromserver);
 509           fromserver = index (fromserver, ' ');
 510           if (! fromserver)
 511             {
 512               strcpy (pop_error,
 513                       "Badly formatted response from server in pop_list");
 514               free ((char *) *IDs);
 515               free ((char *) *sizes);
 516               pop_trash (server);
 517               return (-1);
 518             }
 519           (*sizes)[i] = atoi (fromserver);
 520         }
 521       if (pop_multi_next (server, &fromserver))
 522         {
 523           free ((char *) *IDs);
 524           free ((char *) *sizes);
 525           return (-1);
 526         }
 527       else if (fromserver)
 528         {
 529           strcpy (pop_error,
 530                   "Too many response lines from server in pop_list");
 531           free ((char *) *IDs);
 532           free ((char *) *sizes);
 533           return (-1);
 534         }
 535       (*IDs)[i] = (*sizes)[i] = 0;
 536       return (0);
 537     }
 538 }
 539
 540 /*
 541  * Function: pop_retrieve
 542  *
 543  * Purpose: Retrieve a specified message from the maildrop.
 544  *
 545  * Arguments:
 546  *      server  The server to retrieve from.
 547  *      message The message number to retrieve.
 548  *      markfrom
 549  *              If true, then mark the string "From " at the beginning
 550  *              of lines with '>'.
 551  *
 552  * Return value: A string pointing to the message, if successful, or
 553  *      null with pop_error set if not.
 554  *
 555  * Side effects: May kill connection on error.
 556  */
 557 char *
 558 pop_retrieve (server, message, markfrom)
 559      popserver server;
 560      int message;
 561      int markfrom;
 562 {
 563   int *IDs, *sizes, bufsize, fromcount = 0, cp = 0;
 564   char *ptr, *fromserver;
 565   int ret;
 566
 567   if (server->in_multi)
 568     {
 569       strcpy (pop_error, "In multi-line query in pop_retrieve");
 570       return (0);
 571     }
 572
 573   if (pop_list (server, message, &IDs, &sizes))
 574     return (0);
 575
 576   if (pop_retrieve_first (server, message, &fromserver))
 577     {
 578       return (0);
 579     }
 580
 581   /*
 582    * The "5" below is an arbitrary constant -- I assume that if
 583    * there are "From" lines in the text to be marked, there
 584    * probably won't be more than 5 of them.  If there are, I
 585    * allocate more space for them below.
 586    */
 587   bufsize = sizes[0] + (markfrom ? 5 : 0);
 588   ptr = (char *)malloc (bufsize);
 589   free ((char *) IDs);
 590   free ((char *) sizes);
 591
 592   if (! ptr)
 593     {
 594       strcpy (pop_error, "Out of memory in pop_retrieve");
 595       pop_retrieve_flush (server);
 596       return (0);
 597     }
 598
 599   while (! (ret = pop_retrieve_next (server, &fromserver)))
 600     {
 601       int linesize;
 602
 603       if (! fromserver)
 604         {
 605           ptr[cp] = '\0';
 606           return (ptr);
 607         }
 608       if (markfrom && fromserver[0] == 'F' && fromserver[1] == 'r' &&
 609           fromserver[2] == 'o' && fromserver[3] == 'm' &&
 610           fromserver[4] == ' ')
 611         {
 612           if (++fromcount == 5)
 613             {
 614               bufsize += 5;
 615               ptr = (char *)realloc (ptr, bufsize);
 616               if (! ptr)
 617                 {
 618                   strcpy (pop_error, "Out of memory in pop_retrieve");
 619                   pop_retrieve_flush (server);
 620                   return (0);
 621                 }
 622               fromcount = 0;
 623             }
 624           ptr[cp++] = '>';
 625         }
 626       linesize = strlen (fromserver);
 627       bcopy (fromserver, &ptr[cp], linesize);
 628       cp += linesize;
 629       ptr[cp++] = '\n';
 630     }
 631
 632   if (ret)
 633     {
 634       free (ptr);
 635       return (0);
 636     }
 637 }
 638
 639 int
 640 pop_retrieve_first (server, message, response)
 641      popserver server;
 642      int message;
 643      char **response;
 644 {
 645   sprintf (pop_error, "RETR %d", message);
 646   return (pop_multi_first (server, pop_error, response));
 647 }
 648
 649 int
 650 pop_retrieve_next (server, line)
 651      popserver server;
 652      char **line;
 653 {
 654   return (pop_multi_next (server, line));
 655 }
 656
 657 int
 658 pop_retrieve_flush (server)
 659      popserver server;
 660 {
 661   return (pop_multi_flush (server));
 662 }
 663
 664 int
 665 pop_top_first (server, message, lines, response)
 666      popserver server;
 667      int message, lines;
 668      char **response;
 669 {
 670   sprintf (pop_error, "TOP %d %d", message, lines);
 671   return (pop_multi_first (server, pop_error, response));
 672 }
 673
 674 int
 675 pop_top_next (server, line)
 676      popserver server;
 677      char **line;
 678 {
 679   return (pop_multi_next (server, line));
 680 }
 681
 682 int
 683 pop_top_flush (server)
 684      popserver server;
 685 {
 686   return (pop_multi_flush (server));
 687 }
 688
 689 int
 690 pop_multi_first (server, command, response)
 691      popserver server;
 692      char *command;
 693      char **response;
 694 {
 695   if (server->in_multi)
 696     {
 697       strcpy (pop_error,
 698               "Already in multi-line query in pop_multi_first");
 699       return (-1);
 700     }
 701
 702   if (sendline (server, command) || (! (*response = getline (server))))
 703     {
 704       return (-1);
 705     }
 706
 707   if (0 == strncmp (*response, "-ERR", 4))
 708     {
 709       strncpy (pop_error, *response, ERROR_MAX);
 710       return (-1);
 711     }
 712   else if (0 == strncmp (*response, "+OK", 3))
 713     {
 714       for (*response += 3; **response == ' '; (*response)++) /* empty */;
 715       server->in_multi = 1;
 716       return (0);
 717     }
 718   else
 719     {
 720       strcpy (pop_error,
 721               "Unexpected response from server in pop_multi_first");
 722       return (-1);
 723     }
 724 }
 725
 726 int
 727 pop_multi_next (server, line)
 728      popserver server;
 729      char **line;
 730 {
 731   char *fromserver;
 732
 733   if (! server->in_multi)
 734     {
 735       strcpy (pop_error, "Not in multi-line query in pop_multi_next");
 736       return (-1);
 737     }
 738
 739   fromserver = getline (server);
 740   if (! fromserver)
 741     {
 742       return (-1);
 743     }
 744
 745   if (fromserver[0] == '.')
 746     {
 747       if (! fromserver[1])
 748         {
 749           *line = 0;
 750           server->in_multi = 0;
 751           return (0);
 752         }
 753       else
 754         {
 755           *line = fromserver + 1;
 756           return (0);
 757         }
 758     }
 759   else
 760     {
 761       *line = fromserver;
 762       return (0);
 763     }
 764 }
 765
 766 int
 767 pop_multi_flush (server)
 768      popserver server;
 769 {
 770   char *line;
 771
 772   if (! server->in_multi)
 773     {
 774       return (0);
 775     }
 776
 777   while (! pop_multi_next (server, &line))
 778     {
 779       if (! line)
 780         {
 781           return (0);
 782         }
 783     }
 784
 785   return (-1);
 786 }
 787
 788 /* Function: pop_delete
 789  *
 790  * Purpose: Delete a specified message.
 791  *
 792  * Arguments:
 793  *      server  Server from which to delete the message.
 794  *      message Message to delete.
 795  *
 796  * Return value: 0 on success, non-zero with error in pop_error
 797  *      otherwise.
 798  */
 799 int
 800 pop_delete (server, message)
 801      popserver server;
 802      int message;
 803 {
 804   if (server->in_multi)
 805     {
 806       strcpy (pop_error, "In multi-line query in pop_delete");
 807       return (-1);
 808     }
 809
 810   sprintf (pop_error, "DELE %d", message);
 811
 812   if (sendline (server, pop_error) || getok (server))
 813     return (-1);
 814
 815   return (0);
 816 }
 817
 818 /*
 819  * Function: pop_noop
 820  *
 821  * Purpose: Send a noop command to the server.
 822  *
 823  * Argument:
 824  *      server  The server to send to.
 825  *
 826  * Return value: 0 on success, non-zero with error in pop_error
 827  *      otherwise.
 828  *
 829  * Side effects: Closes connection on error.
 830  */
 831 int
 832 pop_noop (server)
 833      popserver server;
 834 {
 835   if (server->in_multi)
 836     {
 837       strcpy (pop_error, "In multi-line query in pop_noop");
 838       return (-1);
 839     }
 840
 841   if (sendline (server, "NOOP") || getok (server))
 842     return (-1);
 843
 844   return (0);
 845 }
 846
 847 /*
 848  * Function: pop_last
 849  *
 850  * Purpose: Find out the highest seen message from the server.
 851  *
 852  * Arguments:
 853  *      server  The server.
 854  *
 855  * Return value: If successful, the highest seen message, which is
 856  *      greater than or equal to 0.  Otherwise, a negative number with
 857  *      the error explained in pop_error.
 858  *
 859  * Side effects: Closes the connection on error.
 860  */
 861 int
 862 pop_last (server)
 863      popserver server;
 864 {
 865   char *fromserver;
 866
 867   if (server->in_multi)
 868     {
 869       strcpy (pop_error, "In multi-line query in pop_last");
 870       return (-1);
 871     }
 872
 873   if (sendline (server, "LAST"))
 874     return (-1);
 875
 876   if (! (fromserver = getline (server)))
 877     return (-1);
 878
 879   if (! strncmp (fromserver, "-ERR", 4))
 880     {
 881       strncpy (pop_error, fromserver, ERROR_MAX);
 882       return (-1);
 883     }
 884   else if (strncmp (fromserver, "+OK ", 4))
 885     {
 886       strcpy (pop_error, "Unexpected response from server in pop_last");
 887       pop_trash (server);
 888       return (-1);
 889     }
 890   else
 891     {
 892       return (atoi (&fromserver[4]));
 893     }
 894 }
 895
 896 /*
 897  * Function: pop_reset
 898  *
 899  * Purpose: Reset the server to its initial connect state
 900  *
 901  * Arguments:
 902  *      server  The server.
 903  *
 904  * Return value: 0 for success, non-0 with error in pop_error
 905  *      otherwise.
 906  *
 907  * Side effects: Closes the connection on error.
 908  */
 909 int
 910 pop_reset (server)
 911      popserver server;
 912 {
 913   if (pop_retrieve_flush (server))
 914     {
 915       return (-1);
 916     }
 917
 918   if (sendline (server, "RSET") || getok (server))
 919     return (-1);
 920
 921   return (0);
 922 }
 923
 924 /*
 925  * Function: pop_quit
 926  *
 927  * Purpose: Quit the connection to the server,
 928  *
 929  * Arguments:
 930  *      server  The server to quit.
 931  *
 932  * Return value: 0 for success, non-zero otherwise with error in
 933  *      pop_error.
 934  *
 935  * Side Effects: The popserver passed in is unusable after this
 936  *      function is called, even if an error occurs.
 937  */
 938 int
 939 pop_quit (server)
 940      popserver server;
 941 {
 942   int ret = 0;
 943
 944   if (server->file >= 0)
 945     {
 946       if (pop_retrieve_flush (server))
 947         {
 948           ret = -1;
 949         }
 950
 951       if (sendline (server, "QUIT") || getok (server))
 952         {
 953           ret = -1;
 954         }
 955
 956       close (server->file);
 957     }
 958
 959   if (server->buffer)
 960     free (server->buffer);
 961   free ((char *) server);
 962
 963   return (ret);
 964 }
 965
 966 #ifdef WINDOWSNT
 967 static int have_winsock = 0;
 968 #endif
 969
 970 /*
 971  * Function: socket_connection
 972  *
 973  * Purpose: Opens the network connection with the mail host, without
 974  *      doing any sort of I/O with it or anything.
 975  *
 976  * Arguments:
 977  *      host    The host to which to connect.
 978  *      flags   Option flags.
 979  *
 980  * Return value: A file descriptor indicating the connection, or -1
 981  *      indicating failure, in which case an error has been copied
 982  *      into pop_error.
 983  */
 984 static int
 985 socket_connection (host, flags)
 986      char *host;
 987      int flags;
 988 {
 989   struct hostent *hostent;
 990   struct servent *servent;
 991   struct sockaddr_in addr;
 992   char found_port = 0;
 993   char *service;
 994   int sock;
 995 #ifdef KERBEROS
 996 #ifdef KRB5
 997   krb5_error_code rem;
 998   krb5_ccache ccdef;
 999   krb5_principal client, server;
1000   krb5_error *err_ret;
1001   register char *cp;
1002 #else
1003   KTEXT ticket;
1004   MSG_DAT msg_data;
1005   CREDENTIALS cred;
1006   Key_schedule schedule;
1007   int rem;
1008 #endif /* KRB5 */
1009 #endif /* KERBEROS */
1010
1011   int try_count = 0;
1012
1013 #ifdef WINDOWSNT
1014   {
1015     WSADATA winsockData;
1016     if (WSAStartup (0x101, &winsockData) == 0)
1017       have_winsock = 1;
1018   }
1019 #endif
1020
1021   do
1022     {
1023       hostent = gethostbyname (host);
1024       try_count++;
1025       if ((! hostent) && ((h_errno != TRY_AGAIN) || (try_count == 5)))
1026         {
1027           strcpy (pop_error, "Could not determine POP server's address");
1028           return (-1);
1029         }
1030     } while (! hostent);
1031
1032   bzero ((char *) &addr, sizeof (addr));
1033   addr.sin_family = AF_INET;
1034
1035 #ifdef KERBEROS
1036   service = (flags & POP_NO_KERBEROS) ? POP_SERVICE : KPOP_SERVICE;
1037 #else
1038   service = POP_SERVICE;
1039 #endif
1040
1041 #ifdef HESIOD
1042   if (! (flags & POP_NO_HESIOD))
1043     {
1044       servent = hes_getservbyname (service, "tcp");
1045       if (servent)
1046         {
1047           addr.sin_port = servent->s_port;
1048           found_port = 1;
1049         }
1050     }
1051 #endif
1052   if (! found_port)
1053     {
1054       servent = getservbyname (service, "tcp");
1055       if (servent)
1056         {
1057           addr.sin_port = servent->s_port;
1058         }
1059       else
1060         {
1061 #ifdef KERBEROS
1062           addr.sin_port = htons ((flags & POP_NO_KERBEROS) ?
1063                                 POP_PORT : KPOP_PORT);
1064 #else
1065           addr.sin_port = htons (POP_PORT);
1066 #endif
1067         }
1068     }
1069
1070 #define SOCKET_ERROR "Could not create socket for POP connection: "
1071
1072   sock = socket (PF_INET, SOCK_STREAM, 0);
1073   if (sock < 0)
1074     {
1075       strcpy (pop_error, SOCKET_ERROR);
1076       strncat (pop_error, strerror (errno),
1077                ERROR_MAX - sizeof (SOCKET_ERROR));
1078       return (-1);
1079
1080     }
1081
1082   while (*hostent->h_addr_list)
1083     {
1084       bcopy (*hostent->h_addr_list, (char *) &addr.sin_addr,
1085              hostent->h_length);
1086       if (! connect (sock, (struct sockaddr *) &addr, sizeof (addr)))
1087         break;
1088       hostent->h_addr_list++;
1089     }
1090
1091 #define CONNECT_ERROR "Could not connect to POP server: "
1092
1093   if (! *hostent->h_addr_list)
1094     {
1095       CLOSESOCKET (sock);
1096       strcpy (pop_error, CONNECT_ERROR);
1097       strncat (pop_error, strerror (errno),
1098                ERROR_MAX - sizeof (CONNECT_ERROR));
1099       return (-1);
1100
1101     }
1102
1103 #ifdef KERBEROS
1104 #define KRB_ERROR "Kerberos error connecting to POP server: "
1105   if (! (flags & POP_NO_KERBEROS))
1106     {
1107 #ifdef KRB5
1108       krb5_init_ets ();
1109
1110       if (rem = krb5_cc_default (&ccdef))
1111         {
1112         krb5error:
1113           strcpy (pop_error, KRB_ERROR);
1114           strncat (pop_error, error_message (rem),
1115                    ERROR_MAX - sizeof(KRB_ERROR));
1116           CLOSESOCKET (sock);
1117           return (-1);
1118         }
1119
1120       if (rem = krb5_cc_get_principal (ccdef, &client))
1121         {
1122           goto krb5error;
1123         }
1124
1125       for (cp = hostent->h_name; *cp; cp++)
1126         {
1127           if (isupper (*cp))
1128             {
1129               *cp = tolower (*cp);
1130             }
1131         }
1132
1133       if (rem = krb5_sname_to_principal (hostent->h_name, POP_SERVICE,
1134                                          FALSE, &server))
1135         {
1136           goto krb5error;
1137         }
1138
1139       rem = krb5_sendauth ((krb5_pointer) &sock, "KPOPV1.0", client, server,
1140                           AP_OPTS_MUTUAL_REQUIRED,
1141                           0,    /* no checksum */
1142                           0,    /* no creds, use ccache instead */
1143                           ccdef,
1144                           0,    /* don't need seq # */
1145                           0,    /* don't need subsession key */
1146                           &err_ret,
1147                           0);   /* don't need reply */
1148       krb5_free_principal (server);
1149       if (rem)
1150         {
1151           if (err_ret && err_ret->text.length)
1152             {
1153               strcpy (pop_error, KRB_ERROR);
1154               strncat (pop_error, error_message (rem),
1155                        ERROR_MAX - sizeof (KRB_ERROR));
1156               strncat (pop_error, " [server says '",
1157                        ERROR_MAX - strlen (pop_error) - 1);
1158               strncat (pop_error, err_ret->text.data,
1159                        min (ERROR_MAX - strlen (pop_error) - 1,
1160                             err_ret->text.length));
1161               strncat (pop_error, "']",
1162                        ERROR_MAX - strlen (pop_error) - 1);
1163             }
1164           else
1165             {
1166               strcpy (pop_error, KRB_ERROR);
1167               strncat (pop_error, error_message (rem),
1168                        ERROR_MAX - sizeof (KRB_ERROR));
1169             }
1170           if (err_ret)
1171             krb5_free_error (err_ret);
1172
1173           CLOSESOCKET (sock);
1174           return (-1);
1175         }
1176 #else  /* ! KRB5 */
1177       ticket = (KTEXT) malloc (sizeof (KTEXT_ST));
1178       rem = krb_sendauth (0L, sock, ticket, "pop", hostent->h_name,
1179                           (char *) krb_realmofhost (hostent->h_name),
1180                           (unsigned long) 0, &msg_data, &cred, schedule,
1181                           (struct sockaddr_in *) 0,
1182                           (struct sockaddr_in *) 0,
1183                           "KPOPV0.1");
1184       free ((char *) ticket);
1185       if (rem != KSUCCESS)
1186         {
1187           strcpy (pop_error, KRB_ERROR);
1188           strncat (pop_error, krb_err_txt[rem],
1189                    ERROR_MAX - sizeof (KRB_ERROR));
1190           CLOSESOCKET (sock);
1191           return (-1);
1192         }
1193 #endif /* KRB5 */
1194     }
1195 #endif /* KERBEROS */
1196
1197   return (sock);
1198 } /* socket_connection */
1199
1200 /*
1201  * Function: getline
1202  *
1203  * Purpose: Get a line of text from the connection and return a
1204  *      pointer to it.  The carriage return and linefeed at the end of
1205  *      the line are stripped, but periods at the beginnings of lines
1206  *      are NOT dealt with in any special way.
1207  *
1208  * Arguments:
1209  *      server  The server from which to get the line of text.
1210  *
1211  * Returns: A non-null pointer if successful, or a null pointer on any
1212  *      error, with an error message copied into pop_error.
1213  *
1214  * Notes: The line returned is overwritten with each call to getline.
1215  *
1216  * Side effects: Closes the connection on error.
1217  */
1218 static char *
1219 getline (server)
1220      popserver server;
1221 {
1222 #define GETLINE_ERROR "Error reading from server: "
1223
1224   int ret;
1225   int search_offset = 0;
1226
1227   if (server->data)
1228     {
1229       char *cp = find_crlf (server->buffer + server->buffer_index);
1230       if (cp)
1231         {
1232           int found;
1233           int data_used;
1234
1235           found = server->buffer_index;
1236           data_used = (cp + 2) - server->buffer - found;
1237
1238           *cp = '\0';           /* terminate the string to be returned */
1239           server->data -= data_used;
1240           server->buffer_index += data_used;
1241
1242           if (pop_debug)
1243             fprintf (stderr, "<<< %s\n", server->buffer + found);
1244           return (server->buffer + found);
1245         }
1246       else
1247         {
1248           bcopy (server->buffer + server->buffer_index,
1249                  server->buffer, server->data);
1250           /* Record the fact that we've searched the data already in
1251              the buffer for a CRLF, so that when we search below, we
1252              don't have to search the same data twice.  There's a "-
1253              1" here to account for the fact that the last character
1254              of the data we have may be the CR of a CRLF pair, of
1255              which we haven't read the second half yet, so we may have
1256              to search it again when we read more data. */
1257           search_offset = server->data - 1;
1258           server->buffer_index = 0;
1259         }
1260     }
1261   else
1262     {
1263       server->buffer_index = 0;
1264     }
1265
1266   while (1)
1267     {
1268       /* There's a "- 1" here to leave room for the null that we put
1269          at the end of the read data below.  We put the null there so
1270          that find_crlf knows where to stop when we call it. */
1271       if (server->data == server->buffer_size - 1)
1272         {
1273           server->buffer_size += GETLINE_INCR;
1274           server->buffer = (char *)realloc (server->buffer, server->buffer_size);
1275           if (! server->buffer)
1276             {
1277               strcpy (pop_error, "Out of memory in getline");
1278               pop_trash (server);
1279               return (0);
1280             }
1281         }
1282       ret = RECV (server->file, server->buffer + server->data,
1283                   server->buffer_size - server->data - 1, 0);
1284       if (ret < 0)
1285         {
1286           strcpy (pop_error, GETLINE_ERROR);
1287           strncat (pop_error, strerror (errno),
1288                    ERROR_MAX - sizeof (GETLINE_ERROR));
1289           pop_trash (server);
1290           return (0);
1291         }
1292       else if (ret == 0)
1293         {
1294           strcpy (pop_error, "Unexpected EOF from server in getline");
1295           pop_trash (server);
1296           return (0);
1297         }
1298       else
1299         {
1300           char *cp;
1301           server->data += ret;
1302           server->buffer[server->data] = '\0';
1303
1304           cp = find_crlf (server->buffer + search_offset);
1305           if (cp)
1306             {
1307               int data_used = (cp + 2) - server->buffer;
1308               *cp = '\0';
1309               server->data -= data_used;
1310               server->buffer_index = data_used;
1311
1312               if (pop_debug)
1313                 fprintf (stderr, "<<< %s\n", server->buffer);
1314               return (server->buffer);
1315             }
1316           search_offset += ret;
1317         }
1318     }
1319
1320   /* NOTREACHED */
1321 }
1322
1323 /*
1324  * Function: sendline
1325  *
1326  * Purpose: Sends a line of text to the POP server.  The line of text
1327  *      passed into this function should NOT have the carriage return
1328  *      and linefeed on the end of it.  Periods at beginnings of lines
1329  *      will NOT be treated specially by this function.
1330  *
1331  * Arguments:
1332  *      server  The server to which to send the text.
1333  *      line    The line of text to send.
1334  *
1335  * Return value: Upon successful completion, a value of 0 will be
1336  *      returned.  Otherwise, a non-zero value will be returned, and
1337  *      an error will be copied into pop_error.
1338  *
1339  * Side effects: Closes the connection on error.
1340  */
1341 static int
1342 sendline (server, line)
1343      popserver server;
1344      char *line;
1345 {
1346 #define SENDLINE_ERROR "Error writing to POP server: "
1347   int ret;
1348
1349   ret = fullwrite (server->file, line, strlen (line));
1350   if (ret >= 0)
1351     {                           /* 0 indicates that a blank line was written */
1352       ret = fullwrite (server->file, "\r\n", 2);
1353     }
1354
1355   if (ret < 0)
1356     {
1357       pop_trash (server);
1358       strcpy (pop_error, SENDLINE_ERROR);
1359       strncat (pop_error, strerror (errno),
1360                ERROR_MAX - sizeof (SENDLINE_ERROR));
1361       return (ret);
1362     }
1363
1364   if (pop_debug)
1365     fprintf (stderr, ">>> %s\n", line);
1366
1367   return (0);
1368 }
1369
1370 /*
1371  * Procedure: fullwrite
1372  *
1373  * Purpose: Just like write, but keeps trying until the entire string
1374  *      has been written.
1375  *
1376  * Return value: Same as write.  Pop_error is not set.
1377  */
1378 static int
1379 fullwrite (fd, buf, nbytes)
1380      int fd;
1381      char *buf;
1382      int nbytes;
1383 {
1384   char *cp;
1385   int ret;
1386
1387   cp = buf;
1388   while ((ret = SEND (fd, cp, nbytes, 0)) > 0)
1389     {
1390       cp += ret;
1391       nbytes -= ret;
1392     }
1393
1394   return (ret);
1395 }
1396
1397 /*
1398  * Procedure getok
1399  *
1400  * Purpose: Reads a line from the server.  If the return indicator is
1401  *      positive, return with a zero exit status.  If not, return with
1402  *      a negative exit status.
1403  *
1404  * Arguments:
1405  *      server  The server to read from.
1406  *
1407  * Returns: 0 for success, else for failure and puts error in pop_error.
1408  *
1409  * Side effects: On failure, may make the connection unusable.
1410  */
1411 static int
1412 getok (server)
1413      popserver server;
1414 {
1415   char *fromline;
1416
1417   if (! (fromline = getline (server)))
1418     {
1419       return (-1);
1420     }
1421
1422   if (! strncmp (fromline, "+OK", 3))
1423     return (0);
1424   else if (! strncmp (fromline, "-ERR", 4))
1425     {
1426       strncpy (pop_error, fromline, ERROR_MAX);
1427       pop_error[ERROR_MAX-1] = '\0';
1428       return (-1);
1429     }
1430   else
1431     {
1432       strcpy (pop_error,
1433               "Unexpected response from server; expecting +OK or -ERR");
1434       pop_trash (server);
1435       return (-1);
1436     }
1437 }
1438
1439 #if 0
1440 /*
1441  * Function: gettermination
1442  *
1443  * Purpose: Gets the next line and verifies that it is a termination
1444  *      line (nothing but a dot).
1445  *
1446  * Return value: 0 on success, non-zero with pop_error set on error.
1447  *
1448  * Side effects: Closes the connection on error.
1449  */
1450 static int
1451 gettermination (server)
1452      popserver server;
1453 {
1454   char *fromserver;
1455
1456   fromserver = getline (server);
1457   if (! fromserver)
1458     return (-1);
1459
1460   if (strcmp (fromserver, "."))
1461     {
1462       strcpy (pop_error,
1463               "Unexpected response from server in gettermination");
1464       pop_trash (server);
1465       return (-1);
1466     }
1467
1468   return (0);
1469 }
1470 #endif
1471
1472 /*
1473  * Function pop_close
1474  *
1475  * Purpose: Close a pop connection, sending a "RSET" command to try to
1476  *      preserve any changes that were made and a "QUIT" command to
1477  *      try to get the server to quit, but ignoring any responses that
1478  *      are received.
1479  *
1480  * Side effects: The server is unusable after this function returns.
1481  *      Changes made to the maildrop since the session was started (or
1482  *      since the last pop_reset) may be lost.
1483  */
1484 void
1485 pop_close (server)
1486      popserver server;
1487 {
1488   pop_trash (server);
1489   free ((char *) server);
1490
1491   return;
1492 }
1493
1494 /*
1495  * Function: pop_trash
1496  *
1497  * Purpose: Like pop_close or pop_quit, but doesn't deallocate the
1498  *      memory associated with the server.  It is legal to call
1499  *      pop_close or pop_quit after this function has been called.
1500  */
1501 static void
1502 pop_trash (server)
1503      popserver server;
1504 {
1505   if (server->file >= 0)
1506     {
1507       /* avoid recursion; sendline can call pop_trash */
1508       if (server->trash_started)
1509         return;
1510       server->trash_started = 1;
1511
1512       sendline (server, "RSET");
1513       sendline (server, "QUIT");
1514
1515       CLOSESOCKET (server->file);
1516       server->file = -1;
1517       if (server->buffer)
1518         {
1519           free (server->buffer);
1520           server->buffer = 0;
1521         }
1522     }
1523
1524 #ifdef WINDOWSNT
1525   if (have_winsock)
1526     WSACleanup ();
1527 #endif
1528 }
1529
1530 /* Return a pointer to the first CRLF in IN_STRING,
1531    or 0 if it does not contain one.  */
1532
1533 static char *
1534 find_crlf (in_string)
1535      char *in_string;
1536 {
1537   while (1)
1538     {
1539       if (! *in_string)
1540         return (0);
1541       else if (*in_string == '\r')
1542         {
1543           if (*++in_string == '\n')
1544             return (in_string - 1);
1545         }
1546       else
1547         in_string++;
1548     }
1549   /* NOTREACHED */
1550 }
1551
1552 #endif /* MAIL_USE_POP */