crypto/openssh-5/readconf.c

   1 /* $OpenBSD: readconf.c,v 1.167 2008/06/26 11:46:31 grunk Exp $ */
   2 /*
   3  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   4  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   5  *                    All rights reserved
   6  * Functions for reading the configuration files.
   7  *
   8  * As far as I am concerned, the code I have written for this software
   9  * can be used freely for any purpose.  Any derived versions of this
  10  * software must be clearly marked as such, and if the derived work is
  11  * incompatible with the protocol description in the RFC file, it must be
  12  * called by a name other than "ssh" or "Secure Shell".
  13  */
  14
  15 #include "includes.h"
  16
  17 #include <sys/types.h>
  18 #include <sys/stat.h>
  19 #include <sys/socket.h>
  20
  21 #include <netinet/in.h>
  22
  23 #include <ctype.h>
  24 #include <errno.h>
  25 #include <netdb.h>
  26 #include <signal.h>
  27 #include <stdarg.h>
  28 #include <stdio.h>
  29 #include <string.h>
  30 #include <unistd.h>
  31
  32 #include "xmalloc.h"
  33 #include "ssh.h"
  34 #include "compat.h"
  35 #include "cipher.h"
  36 #include "pathnames.h"
  37 #include "log.h"
  38 #include "key.h"
  39 #include "readconf.h"
  40 #include "match.h"
  41 #include "misc.h"
  42 #include "buffer.h"
  43 #include "kex.h"
  44 #include "mac.h"
  45
  46 /* Format of the configuration file:
  47
  48    # Configuration data is parsed as follows:
  49    #  1. command line options
  50    #  2. user-specific file
  51    #  3. system-wide file
  52    # Any configuration value is only changed the first time it is set.
  53    # Thus, host-specific definitions should be at the beginning of the
  54    # configuration file, and defaults at the end.
  55
  56    # Host-specific declarations.  These may override anything above.  A single
  57    # host may match multiple declarations; these are processed in the order
  58    # that they are given in.
  59
  60    Host *.ngs.fi ngs.fi
  61      User foo
  62
  63    Host fake.com
  64      HostName another.host.name.real.org
  65      User blaah
  66      Port 34289
  67      ForwardX11 no
  68      ForwardAgent no
  69
  70    Host books.com
  71      RemoteForward 9999 shadows.cs.hut.fi:9999
  72      Cipher 3des
  73
  74    Host fascist.blob.com
  75      Port 23123
  76      User tylonen
  77      PasswordAuthentication no
  78
  79    Host puukko.hut.fi
  80      User t35124p
  81      ProxyCommand ssh-proxy %h %p
  82
  83    Host *.fr
  84      PublicKeyAuthentication no
  85
  86    Host *.su
  87      Cipher none
  88      PasswordAuthentication no
  89
  90    Host vpn.fake.com
  91      Tunnel yes
  92      TunnelDevice 3
  93
  94    # Defaults for various options
  95    Host *
  96      ForwardAgent no
  97      ForwardX11 no
  98      PasswordAuthentication yes
  99      RSAAuthentication yes
 100      RhostsRSAAuthentication yes
 101      StrictHostKeyChecking yes
 102      TcpKeepAlive no
 103      IdentityFile ~/.ssh/identity
 104      Port 22
 105      EscapeChar ~
 106
 107 */
 108
 109 /* Keyword tokens. */
 110
 111 typedef enum {
 112         oBadOption,
 113         oForwardAgent, oForwardX11, oForwardX11Trusted, oGatewayPorts,
 114         oExitOnForwardFailure,
 115         oPasswordAuthentication, oRSAAuthentication,
 116         oChallengeResponseAuthentication, oXAuthLocation,
 117         oIdentityFile, oHostName, oPort, oCipher, oRemoteForward, oLocalForward,
 118         oUser, oHost, oEscapeChar, oRhostsRSAAuthentication, oProxyCommand,
 119         oGlobalKnownHostsFile, oUserKnownHostsFile, oConnectionAttempts,
 120         oBatchMode, oCheckHostIP, oStrictHostKeyChecking, oCompression,
 121         oCompressionLevel, oTCPKeepAlive, oNumberOfPasswordPrompts,
 122         oUsePrivilegedPort, oLogLevel, oCiphers, oProtocol, oMacs,
 123         oGlobalKnownHostsFile2, oUserKnownHostsFile2, oPubkeyAuthentication,
 124         oKbdInteractiveAuthentication, oKbdInteractiveDevices, oHostKeyAlias,
 125         oDynamicForward, oPreferredAuthentications, oHostbasedAuthentication,
 126         oHostKeyAlgorithms, oBindAddress, oSmartcardDevice,
 127         oClearAllForwardings, oNoHostAuthenticationForLocalhost,
 128         oEnableSSHKeysign, oRekeyLimit, oVerifyHostKeyDNS, oConnectTimeout,
 129         oAddressFamily, oGssAuthentication, oGssDelegateCreds,
 130         oServerAliveInterval, oServerAliveCountMax, oIdentitiesOnly,
 131         oSendEnv, oControlPath, oControlMaster, oHashKnownHosts,
 132         oTunnel, oTunnelDevice, oLocalCommand, oPermitLocalCommand,
 133         oVisualHostKey,
 134         oDeprecated, oUnsupported
 135 } OpCodes;
 136
 137 /* Textual representations of the tokens. */
 138
 139 static struct {
 140         const char *name;
 141         OpCodes opcode;
 142 } keywords[] = {
 143         { "forwardagent", oForwardAgent },
 144         { "forwardx11", oForwardX11 },
 145         { "forwardx11trusted", oForwardX11Trusted },
 146         { "exitonforwardfailure", oExitOnForwardFailure },
 147         { "xauthlocation", oXAuthLocation },
 148         { "gatewayports", oGatewayPorts },
 149         { "useprivilegedport", oUsePrivilegedPort },
 150         { "rhostsauthentication", oDeprecated },
 151         { "passwordauthentication", oPasswordAuthentication },
 152         { "kbdinteractiveauthentication", oKbdInteractiveAuthentication },
 153         { "kbdinteractivedevices", oKbdInteractiveDevices },
 154         { "rsaauthentication", oRSAAuthentication },
 155         { "pubkeyauthentication", oPubkeyAuthentication },
 156         { "dsaauthentication", oPubkeyAuthentication },             /* alias */
 157         { "rhostsrsaauthentication", oRhostsRSAAuthentication },
 158         { "hostbasedauthentication", oHostbasedAuthentication },
 159         { "challengeresponseauthentication", oChallengeResponseAuthentication },
 160         { "skeyauthentication", oChallengeResponseAuthentication }, /* alias */
 161         { "tisauthentication", oChallengeResponseAuthentication },  /* alias */
 162         { "kerberosauthentication", oUnsupported },
 163         { "kerberostgtpassing", oUnsupported },
 164         { "afstokenpassing", oUnsupported },
 165 #if defined(GSSAPI)
 166         { "gssapiauthentication", oGssAuthentication },
 167         { "gssapidelegatecredentials", oGssDelegateCreds },
 168 #else
 169         { "gssapiauthentication", oUnsupported },
 170         { "gssapidelegatecredentials", oUnsupported },
 171 #endif
 172         { "fallbacktorsh", oDeprecated },
 173         { "usersh", oDeprecated },
 174         { "identityfile", oIdentityFile },
 175         { "identityfile2", oIdentityFile },                     /* alias */
 176         { "identitiesonly", oIdentitiesOnly },
 177         { "hostname", oHostName },
 178         { "hostkeyalias", oHostKeyAlias },
 179         { "proxycommand", oProxyCommand },
 180         { "port", oPort },
 181         { "cipher", oCipher },
 182         { "ciphers", oCiphers },
 183         { "macs", oMacs },
 184         { "protocol", oProtocol },
 185         { "remoteforward", oRemoteForward },
 186         { "localforward", oLocalForward },
 187         { "user", oUser },
 188         { "host", oHost },
 189         { "escapechar", oEscapeChar },
 190         { "globalknownhostsfile", oGlobalKnownHostsFile },
 191         { "userknownhostsfile", oUserKnownHostsFile },          /* obsolete */
 192         { "globalknownhostsfile2", oGlobalKnownHostsFile2 },
 193         { "userknownhostsfile2", oUserKnownHostsFile2 },        /* obsolete */
 194         { "connectionattempts", oConnectionAttempts },
 195         { "batchmode", oBatchMode },
 196         { "checkhostip", oCheckHostIP },
 197         { "stricthostkeychecking", oStrictHostKeyChecking },
 198         { "compression", oCompression },
 199         { "compressionlevel", oCompressionLevel },
 200         { "tcpkeepalive", oTCPKeepAlive },
 201         { "keepalive", oTCPKeepAlive },                         /* obsolete */
 202         { "numberofpasswordprompts", oNumberOfPasswordPrompts },
 203         { "loglevel", oLogLevel },
 204         { "dynamicforward", oDynamicForward },
 205         { "preferredauthentications", oPreferredAuthentications },
 206         { "hostkeyalgorithms", oHostKeyAlgorithms },
 207         { "bindaddress", oBindAddress },
 208 #ifdef SMARTCARD
 209         { "smartcarddevice", oSmartcardDevice },
 210 #else
 211         { "smartcarddevice", oUnsupported },
 212 #endif
 213         { "clearallforwardings", oClearAllForwardings },
 214         { "enablesshkeysign", oEnableSSHKeysign },
 215         { "verifyhostkeydns", oVerifyHostKeyDNS },
 216         { "nohostauthenticationforlocalhost", oNoHostAuthenticationForLocalhost },
 217         { "rekeylimit", oRekeyLimit },
 218         { "connecttimeout", oConnectTimeout },
 219         { "addressfamily", oAddressFamily },
 220         { "serveraliveinterval", oServerAliveInterval },
 221         { "serveralivecountmax", oServerAliveCountMax },
 222         { "sendenv", oSendEnv },
 223         { "controlpath", oControlPath },
 224         { "controlmaster", oControlMaster },
 225         { "hashknownhosts", oHashKnownHosts },
 226         { "tunnel", oTunnel },
 227         { "tunneldevice", oTunnelDevice },
 228         { "localcommand", oLocalCommand },
 229         { "permitlocalcommand", oPermitLocalCommand },
 230         { "visualhostkey", oVisualHostKey },
 231         { NULL, oBadOption }
 232 };
 233
 234 /*
 235  * Adds a local TCP/IP port forward to options.  Never returns if there is an
 236  * error.
 237  */
 238
 239 void
 240 add_local_forward(Options *options, const Forward *newfwd)
 241 {
 242         Forward *fwd;
 243 #ifndef NO_IPPORT_RESERVED_CONCEPT
 244         extern uid_t original_real_uid;
 245         if (newfwd->listen_port < IPPORT_RESERVED && original_real_uid != 0)
 246                 fatal("Privileged ports can only be forwarded by root.");
 247 #endif
 248         if (options->num_local_forwards >= SSH_MAX_FORWARDS_PER_DIRECTION)
 249                 fatal("Too many local forwards (max %d).", SSH_MAX_FORWARDS_PER_DIRECTION);
 250         fwd = &options->local_forwards[options->num_local_forwards++];
 251
 252         fwd->listen_host = (newfwd->listen_host == NULL) ?
 253             NULL : xstrdup(newfwd->listen_host);
 254         fwd->listen_port = newfwd->listen_port;
 255         fwd->connect_host = xstrdup(newfwd->connect_host);
 256         fwd->connect_port = newfwd->connect_port;
 257 }
 258
 259 /*
 260  * Adds a remote TCP/IP port forward to options.  Never returns if there is
 261  * an error.
 262  */
 263
 264 void
 265 add_remote_forward(Options *options, const Forward *newfwd)
 266 {
 267         Forward *fwd;
 268         if (options->num_remote_forwards >= SSH_MAX_FORWARDS_PER_DIRECTION)
 269                 fatal("Too many remote forwards (max %d).",
 270                     SSH_MAX_FORWARDS_PER_DIRECTION);
 271         fwd = &options->remote_forwards[options->num_remote_forwards++];
 272
 273         fwd->listen_host = (newfwd->listen_host == NULL) ?
 274             NULL : xstrdup(newfwd->listen_host);
 275         fwd->listen_port = newfwd->listen_port;
 276         fwd->connect_host = xstrdup(newfwd->connect_host);
 277         fwd->connect_port = newfwd->connect_port;
 278 }
 279
 280 static void
 281 clear_forwardings(Options *options)
 282 {
 283         int i;
 284
 285         for (i = 0; i < options->num_local_forwards; i++) {
 286                 if (options->local_forwards[i].listen_host != NULL)
 287                         xfree(options->local_forwards[i].listen_host);
 288                 xfree(options->local_forwards[i].connect_host);
 289         }
 290         options->num_local_forwards = 0;
 291         for (i = 0; i < options->num_remote_forwards; i++) {
 292                 if (options->remote_forwards[i].listen_host != NULL)
 293                         xfree(options->remote_forwards[i].listen_host);
 294                 xfree(options->remote_forwards[i].connect_host);
 295         }
 296         options->num_remote_forwards = 0;
 297         options->tun_open = SSH_TUNMODE_NO;
 298 }
 299
 300 /*
 301  * Returns the number of the token pointed to by cp or oBadOption.
 302  */
 303
 304 static OpCodes
 305 parse_token(const char *cp, const char *filename, int linenum)
 306 {
 307         u_int i;
 308
 309         for (i = 0; keywords[i].name; i++)
 310                 if (strcasecmp(cp, keywords[i].name) == 0)
 311                         return keywords[i].opcode;
 312
 313         error("%s: line %d: Bad configuration option: %s",
 314             filename, linenum, cp);
 315         return oBadOption;
 316 }
 317
 318 /*
 319  * Processes a single option line as used in the configuration files. This
 320  * only sets those values that have not already been set.
 321  */
 322 #define WHITESPACE " \t\r\n"
 323
 324 int
 325 process_config_line(Options *options, const char *host,
 326                     char *line, const char *filename, int linenum,
 327                     int *activep)
 328 {
 329         char *s, **charptr, *endofnumber, *keyword, *arg, *arg2, fwdarg[256];
 330         int opcode, *intptr, value, value2, scale;
 331         LogLevel *log_level_ptr;
 332         long long orig, val64;
 333         size_t len;
 334         Forward fwd;
 335
 336         /* Strip trailing whitespace */
 337         for (len = strlen(line) - 1; len > 0; len--) {
 338                 if (strchr(WHITESPACE, line[len]) == NULL)
 339                         break;
 340                 line[len] = '\0';
 341         }
 342
 343         s = line;
 344         /* Get the keyword. (Each line is supposed to begin with a keyword). */
 345         if ((keyword = strdelim(&s)) == NULL)
 346                 return 0;
 347         /* Ignore leading whitespace. */
 348         if (*keyword == '\0')
 349                 keyword = strdelim(&s);
 350         if (keyword == NULL || !*keyword || *keyword == '\n' || *keyword == '#')
 351                 return 0;
 352
 353         opcode = parse_token(keyword, filename, linenum);
 354
 355         switch (opcode) {
 356         case oBadOption:
 357                 /* don't panic, but count bad options */
 358                 return -1;
 359                 /* NOTREACHED */
 360         case oConnectTimeout:
 361                 intptr = &options->connection_timeout;
 362 parse_time:
 363                 arg = strdelim(&s);
 364                 if (!arg || *arg == '\0')
 365                         fatal("%s line %d: missing time value.",
 366                             filename, linenum);
 367                 if ((value = convtime(arg)) == -1)
 368                         fatal("%s line %d: invalid time value.",
 369                             filename, linenum);
 370                 if (*activep && *intptr == -1)
 371                         *intptr = value;
 372                 break;
 373
 374         case oForwardAgent:
 375                 intptr = &options->forward_agent;
 376 parse_flag:
 377                 arg = strdelim(&s);
 378                 if (!arg || *arg == '\0')
 379                         fatal("%.200s line %d: Missing yes/no argument.", filename, linenum);
 380                 value = 0;      /* To avoid compiler warning... */
 381                 if (strcmp(arg, "yes") == 0 || strcmp(arg, "true") == 0)
 382                         value = 1;
 383                 else if (strcmp(arg, "no") == 0 || strcmp(arg, "false") == 0)
 384                         value = 0;
 385                 else
 386                         fatal("%.200s line %d: Bad yes/no argument.", filename, linenum);
 387                 if (*activep && *intptr == -1)
 388                         *intptr = value;
 389                 break;
 390
 391         case oForwardX11:
 392                 intptr = &options->forward_x11;
 393                 goto parse_flag;
 394
 395         case oForwardX11Trusted:
 396                 intptr = &options->forward_x11_trusted;
 397                 goto parse_flag;
 398
 399         case oGatewayPorts:
 400                 intptr = &options->gateway_ports;
 401                 goto parse_flag;
 402
 403         case oExitOnForwardFailure:
 404                 intptr = &options->exit_on_forward_failure;
 405                 goto parse_flag;
 406
 407         case oUsePrivilegedPort:
 408                 intptr = &options->use_privileged_port;
 409                 goto parse_flag;
 410
 411         case oPasswordAuthentication:
 412                 intptr = &options->password_authentication;
 413                 goto parse_flag;
 414
 415         case oKbdInteractiveAuthentication:
 416                 intptr = &options->kbd_interactive_authentication;
 417                 goto parse_flag;
 418
 419         case oKbdInteractiveDevices:
 420                 charptr = &options->kbd_interactive_devices;
 421                 goto parse_string;
 422
 423         case oPubkeyAuthentication:
 424                 intptr = &options->pubkey_authentication;
 425                 goto parse_flag;
 426
 427         case oRSAAuthentication:
 428                 intptr = &options->rsa_authentication;
 429                 goto parse_flag;
 430
 431         case oRhostsRSAAuthentication:
 432                 intptr = &options->rhosts_rsa_authentication;
 433                 goto parse_flag;
 434
 435         case oHostbasedAuthentication:
 436                 intptr = &options->hostbased_authentication;
 437                 goto parse_flag;
 438
 439         case oChallengeResponseAuthentication:
 440                 intptr = &options->challenge_response_authentication;
 441                 goto parse_flag;
 442
 443         case oGssAuthentication:
 444                 intptr = &options->gss_authentication;
 445                 goto parse_flag;
 446
 447         case oGssDelegateCreds:
 448                 intptr = &options->gss_deleg_creds;
 449                 goto parse_flag;
 450
 451         case oBatchMode:
 452                 intptr = &options->batch_mode;
 453                 goto parse_flag;
 454
 455         case oCheckHostIP:
 456                 intptr = &options->check_host_ip;
 457                 goto parse_flag;
 458
 459         case oVerifyHostKeyDNS:
 460                 intptr = &options->verify_host_key_dns;
 461                 goto parse_yesnoask;
 462
 463         case oStrictHostKeyChecking:
 464                 intptr = &options->strict_host_key_checking;
 465 parse_yesnoask:
 466                 arg = strdelim(&s);
 467                 if (!arg || *arg == '\0')
 468                         fatal("%.200s line %d: Missing yes/no/ask argument.",
 469                             filename, linenum);
 470                 value = 0;      /* To avoid compiler warning... */
 471                 if (strcmp(arg, "yes") == 0 || strcmp(arg, "true") == 0)
 472                         value = 1;
 473                 else if (strcmp(arg, "no") == 0 || strcmp(arg, "false") == 0)
 474                         value = 0;
 475                 else if (strcmp(arg, "ask") == 0)
 476                         value = 2;
 477                 else
 478                         fatal("%.200s line %d: Bad yes/no/ask argument.", filename, linenum);
 479                 if (*activep && *intptr == -1)
 480                         *intptr = value;
 481                 break;
 482
 483         case oCompression:
 484                 intptr = &options->compression;
 485                 goto parse_flag;
 486
 487         case oTCPKeepAlive:
 488                 intptr = &options->tcp_keep_alive;
 489                 goto parse_flag;
 490
 491         case oNoHostAuthenticationForLocalhost:
 492                 intptr = &options->no_host_authentication_for_localhost;
 493                 goto parse_flag;
 494
 495         case oNumberOfPasswordPrompts:
 496                 intptr = &options->number_of_password_prompts;
 497                 goto parse_int;
 498
 499         case oCompressionLevel:
 500                 intptr = &options->compression_level;
 501                 goto parse_int;
 502
 503         case oRekeyLimit:
 504                 arg = strdelim(&s);
 505                 if (!arg || *arg == '\0')
 506                         fatal("%.200s line %d: Missing argument.", filename, linenum);
 507                 if (arg[0] < '0' || arg[0] > '9')
 508                         fatal("%.200s line %d: Bad number.", filename, linenum);
 509                 orig = val64 = strtoll(arg, &endofnumber, 10);
 510                 if (arg == endofnumber)
 511                         fatal("%.200s line %d: Bad number.", filename, linenum);
 512                 switch (toupper(*endofnumber)) {
 513                 case '\0':
 514                         scale = 1;
 515                         break;
 516                 case 'K':
 517                         scale = 1<<10;
 518                         break;
 519                 case 'M':
 520                         scale = 1<<20;
 521                         break;
 522                 case 'G':
 523                         scale = 1<<30;
 524                         break;
 525                 default:
 526                         fatal("%.200s line %d: Invalid RekeyLimit suffix",
 527                             filename, linenum);
 528                 }
 529                 val64 *= scale;
 530                 /* detect integer wrap and too-large limits */
 531                 if ((val64 / scale) != orig || val64 > UINT_MAX)
 532                         fatal("%.200s line %d: RekeyLimit too large",
 533                             filename, linenum);
 534                 if (val64 < 16)
 535                         fatal("%.200s line %d: RekeyLimit too small",
 536                             filename, linenum);
 537                 if (*activep && options->rekey_limit == -1)
 538                         options->rekey_limit = (u_int32_t)val64;
 539                 break;
 540
 541         case oIdentityFile:
 542                 arg = strdelim(&s);
 543                 if (!arg || *arg == '\0')
 544                         fatal("%.200s line %d: Missing argument.", filename, linenum);
 545                 if (*activep) {
 546                         intptr = &options->num_identity_files;
 547                         if (*intptr >= SSH_MAX_IDENTITY_FILES)
 548                                 fatal("%.200s line %d: Too many identity files specified (max %d).",
 549                                     filename, linenum, SSH_MAX_IDENTITY_FILES);
 550                         charptr = &options->identity_files[*intptr];
 551                         *charptr = xstrdup(arg);
 552                         *intptr = *intptr + 1;
 553                 }
 554                 break;
 555
 556         case oXAuthLocation:
 557                 charptr=&options->xauth_location;
 558                 goto parse_string;
 559
 560         case oUser:
 561                 charptr = &options->user;
 562 parse_string:
 563                 arg = strdelim(&s);
 564                 if (!arg || *arg == '\0')
 565                         fatal("%.200s line %d: Missing argument.", filename, linenum);
 566                 if (*activep && *charptr == NULL)
 567                         *charptr = xstrdup(arg);
 568                 break;
 569
 570         case oGlobalKnownHostsFile:
 571                 charptr = &options->system_hostfile;
 572                 goto parse_string;
 573
 574         case oUserKnownHostsFile:
 575                 charptr = &options->user_hostfile;
 576                 goto parse_string;
 577
 578         case oGlobalKnownHostsFile2:
 579                 charptr = &options->system_hostfile2;
 580                 goto parse_string;
 581
 582         case oUserKnownHostsFile2:
 583                 charptr = &options->user_hostfile2;
 584                 goto parse_string;
 585
 586         case oHostName:
 587                 charptr = &options->hostname;
 588                 goto parse_string;
 589
 590         case oHostKeyAlias:
 591                 charptr = &options->host_key_alias;
 592                 goto parse_string;
 593
 594         case oPreferredAuthentications:
 595                 charptr = &options->preferred_authentications;
 596                 goto parse_string;
 597
 598         case oBindAddress:
 599                 charptr = &options->bind_address;
 600                 goto parse_string;
 601
 602         case oSmartcardDevice:
 603                 charptr = &options->smartcard_device;
 604                 goto parse_string;
 605
 606         case oProxyCommand:
 607                 charptr = &options->proxy_command;
 608 parse_command:
 609                 if (s == NULL)
 610                         fatal("%.200s line %d: Missing argument.", filename, linenum);
 611                 len = strspn(s, WHITESPACE "=");
 612                 if (*activep && *charptr == NULL)
 613                         *charptr = xstrdup(s + len);
 614                 return 0;
 615
 616         case oPort:
 617                 intptr = &options->port;
 618 parse_int:
 619                 arg = strdelim(&s);
 620                 if (!arg || *arg == '\0')
 621                         fatal("%.200s line %d: Missing argument.", filename, linenum);
 622                 if (arg[0] < '0' || arg[0] > '9')
 623                         fatal("%.200s line %d: Bad number.", filename, linenum);
 624
 625                 /* Octal, decimal, or hex format? */
 626                 value = strtol(arg, &endofnumber, 0);
 627                 if (arg == endofnumber)
 628                         fatal("%.200s line %d: Bad number.", filename, linenum);
 629                 if (*activep && *intptr == -1)
 630                         *intptr = value;
 631                 break;
 632
 633         case oConnectionAttempts:
 634                 intptr = &options->connection_attempts;
 635                 goto parse_int;
 636
 637         case oCipher:
 638                 intptr = &options->cipher;
 639                 arg = strdelim(&s);
 640                 if (!arg || *arg == '\0')
 641                         fatal("%.200s line %d: Missing argument.", filename, linenum);
 642                 value = cipher_number(arg);
 643                 if (value == -1)
 644                         fatal("%.200s line %d: Bad cipher '%s'.",
 645                             filename, linenum, arg ? arg : "<NONE>");
 646                 if (*activep && *intptr == -1)
 647                         *intptr = value;
 648                 break;
 649
 650         case oCiphers:
 651                 arg = strdelim(&s);
 652                 if (!arg || *arg == '\0')
 653                         fatal("%.200s line %d: Missing argument.", filename, linenum);
 654                 if (!ciphers_valid(arg))
 655                         fatal("%.200s line %d: Bad SSH2 cipher spec '%s'.",
 656                             filename, linenum, arg ? arg : "<NONE>");
 657                 if (*activep && options->ciphers == NULL)
 658                         options->ciphers = xstrdup(arg);
 659                 break;
 660
 661         case oMacs:
 662                 arg = strdelim(&s);
 663                 if (!arg || *arg == '\0')
 664                         fatal("%.200s line %d: Missing argument.", filename, linenum);
 665                 if (!mac_valid(arg))
 666                         fatal("%.200s line %d: Bad SSH2 Mac spec '%s'.",
 667                             filename, linenum, arg ? arg : "<NONE>");
 668                 if (*activep && options->macs == NULL)
 669                         options->macs = xstrdup(arg);
 670                 break;
 671
 672         case oHostKeyAlgorithms:
 673                 arg = strdelim(&s);
 674                 if (!arg || *arg == '\0')
 675                         fatal("%.200s line %d: Missing argument.", filename, linenum);
 676                 if (!key_names_valid2(arg))
 677                         fatal("%.200s line %d: Bad protocol 2 host key algorithms '%s'.",
 678                             filename, linenum, arg ? arg : "<NONE>");
 679                 if (*activep && options->hostkeyalgorithms == NULL)
 680                         options->hostkeyalgorithms = xstrdup(arg);
 681                 break;
 682
 683         case oProtocol:
 684                 intptr = &options->protocol;
 685                 arg = strdelim(&s);
 686                 if (!arg || *arg == '\0')
 687                         fatal("%.200s line %d: Missing argument.", filename, linenum);
 688                 value = proto_spec(arg);
 689                 if (value == SSH_PROTO_UNKNOWN)
 690                         fatal("%.200s line %d: Bad protocol spec '%s'.",
 691                             filename, linenum, arg ? arg : "<NONE>");
 692                 if (*activep && *intptr == SSH_PROTO_UNKNOWN)
 693                         *intptr = value;
 694                 break;
 695
 696         case oLogLevel:
 697                 log_level_ptr = &options->log_level;
 698                 arg = strdelim(&s);
 699                 value = log_level_number(arg);
 700                 if (value == SYSLOG_LEVEL_NOT_SET)
 701                         fatal("%.200s line %d: unsupported log level '%s'",
 702                             filename, linenum, arg ? arg : "<NONE>");
 703                 if (*activep && *log_level_ptr == SYSLOG_LEVEL_NOT_SET)
 704                         *log_level_ptr = (LogLevel) value;
 705                 break;
 706
 707         case oLocalForward:
 708         case oRemoteForward:
 709                 arg = strdelim(&s);
 710                 if (arg == NULL || *arg == '\0')
 711                         fatal("%.200s line %d: Missing port argument.",
 712                             filename, linenum);
 713                 arg2 = strdelim(&s);
 714                 if (arg2 == NULL || *arg2 == '\0')
 715                         fatal("%.200s line %d: Missing target argument.",
 716                             filename, linenum);
 717
 718                 /* construct a string for parse_forward */
 719                 snprintf(fwdarg, sizeof(fwdarg), "%s:%s", arg, arg2);
 720
 721                 if (parse_forward(&fwd, fwdarg) == 0)
 722                         fatal("%.200s line %d: Bad forwarding specification.",
 723                             filename, linenum);
 724
 725                 if (*activep) {
 726                         if (opcode == oLocalForward)
 727                                 add_local_forward(options, &fwd);
 728                         else if (opcode == oRemoteForward)
 729                                 add_remote_forward(options, &fwd);
 730                 }
 731                 break;
 732
 733         case oDynamicForward:
 734                 arg = strdelim(&s);
 735                 if (!arg || *arg == '\0')
 736                         fatal("%.200s line %d: Missing port argument.",
 737                             filename, linenum);
 738                 memset(&fwd, '\0', sizeof(fwd));
 739                 fwd.connect_host = "socks";
 740                 fwd.listen_host = hpdelim(&arg);
 741                 if (fwd.listen_host == NULL ||
 742                     strlen(fwd.listen_host) >= NI_MAXHOST)
 743                         fatal("%.200s line %d: Bad forwarding specification.",
 744                             filename, linenum);
 745                 if (arg) {
 746                         fwd.listen_port = a2port(arg);
 747                         fwd.listen_host = cleanhostname(fwd.listen_host);
 748                 } else {
 749                         fwd.listen_port = a2port(fwd.listen_host);
 750                         fwd.listen_host = NULL;
 751                 }
 752                 if (fwd.listen_port == 0)
 753                         fatal("%.200s line %d: Badly formatted port number.",
 754                             filename, linenum);
 755                 if (*activep)
 756                         add_local_forward(options, &fwd);
 757                 break;
 758
 759         case oClearAllForwardings:
 760                 intptr = &options->clear_forwardings;
 761                 goto parse_flag;
 762
 763         case oHost:
 764                 *activep = 0;
 765                 while ((arg = strdelim(&s)) != NULL && *arg != '\0')
 766                         if (match_pattern(host, arg)) {
 767                                 debug("Applying options for %.100s", arg);
 768                                 *activep = 1;
 769                                 break;
 770                         }
 771                 /* Avoid garbage check below, as strdelim is done. */
 772                 return 0;
 773
 774         case oEscapeChar:
 775                 intptr = &options->escape_char;
 776                 arg = strdelim(&s);
 777                 if (!arg || *arg == '\0')
 778                         fatal("%.200s line %d: Missing argument.", filename, linenum);
 779                 if (arg[0] == '^' && arg[2] == 0 &&
 780                     (u_char) arg[1] >= 64 && (u_char) arg[1] < 128)
 781                         value = (u_char) arg[1] & 31;
 782                 else if (strlen(arg) == 1)
 783                         value = (u_char) arg[0];
 784                 else if (strcmp(arg, "none") == 0)
 785                         value = SSH_ESCAPECHAR_NONE;
 786                 else {
 787                         fatal("%.200s line %d: Bad escape character.",
 788                             filename, linenum);
 789                         /* NOTREACHED */
 790                         value = 0;      /* Avoid compiler warning. */
 791                 }
 792                 if (*activep && *intptr == -1)
 793                         *intptr = value;
 794                 break;
 795
 796         case oAddressFamily:
 797                 arg = strdelim(&s);
 798                 if (!arg || *arg == '\0')
 799                         fatal("%s line %d: missing address family.",
 800                             filename, linenum);
 801                 intptr = &options->address_family;
 802                 if (strcasecmp(arg, "inet") == 0)
 803                         value = AF_INET;
 804                 else if (strcasecmp(arg, "inet6") == 0)
 805                         value = AF_INET6;
 806                 else if (strcasecmp(arg, "any") == 0)
 807                         value = AF_UNSPEC;
 808                 else
 809                         fatal("Unsupported AddressFamily \"%s\"", arg);
 810                 if (*activep && *intptr == -1)
 811                         *intptr = value;
 812                 break;
 813
 814         case oEnableSSHKeysign:
 815                 intptr = &options->enable_ssh_keysign;
 816                 goto parse_flag;
 817
 818         case oIdentitiesOnly:
 819                 intptr = &options->identities_only;
 820                 goto parse_flag;
 821
 822         case oServerAliveInterval:
 823                 intptr = &options->server_alive_interval;
 824                 goto parse_time;
 825
 826         case oServerAliveCountMax:
 827                 intptr = &options->server_alive_count_max;
 828                 goto parse_int;
 829
 830         case oSendEnv:
 831                 while ((arg = strdelim(&s)) != NULL && *arg != '\0') {
 832                         if (strchr(arg, '=') != NULL)
 833                                 fatal("%s line %d: Invalid environment name.",
 834                                     filename, linenum);
 835                         if (!*activep)
 836                                 continue;
 837                         if (options->num_send_env >= MAX_SEND_ENV)
 838                                 fatal("%s line %d: too many send env.",
 839                                     filename, linenum);
 840                         options->send_env[options->num_send_env++] =
 841                             xstrdup(arg);
 842                 }
 843                 break;
 844
 845         case oControlPath:
 846                 charptr = &options->control_path;
 847                 goto parse_string;
 848
 849         case oControlMaster:
 850                 intptr = &options->control_master;
 851                 arg = strdelim(&s);
 852                 if (!arg || *arg == '\0')
 853                         fatal("%.200s line %d: Missing ControlMaster argument.",
 854                             filename, linenum);
 855                 value = 0;      /* To avoid compiler warning... */
 856                 if (strcmp(arg, "yes") == 0 || strcmp(arg, "true") == 0)
 857                         value = SSHCTL_MASTER_YES;
 858                 else if (strcmp(arg, "no") == 0 || strcmp(arg, "false") == 0)
 859                         value = SSHCTL_MASTER_NO;
 860                 else if (strcmp(arg, "auto") == 0)
 861                         value = SSHCTL_MASTER_AUTO;
 862                 else if (strcmp(arg, "ask") == 0)
 863                         value = SSHCTL_MASTER_ASK;
 864                 else if (strcmp(arg, "autoask") == 0)
 865                         value = SSHCTL_MASTER_AUTO_ASK;
 866                 else
 867                         fatal("%.200s line %d: Bad ControlMaster argument.",
 868                             filename, linenum);
 869                 if (*activep && *intptr == -1)
 870                         *intptr = value;
 871                 break;
 872
 873         case oHashKnownHosts:
 874                 intptr = &options->hash_known_hosts;
 875                 goto parse_flag;
 876
 877         case oTunnel:
 878                 intptr = &options->tun_open;
 879                 arg = strdelim(&s);
 880                 if (!arg || *arg == '\0')
 881                         fatal("%s line %d: Missing yes/point-to-point/"
 882                             "ethernet/no argument.", filename, linenum);
 883                 value = 0;      /* silence compiler */
 884                 if (strcasecmp(arg, "ethernet") == 0)
 885                         value = SSH_TUNMODE_ETHERNET;
 886                 else if (strcasecmp(arg, "point-to-point") == 0)
 887                         value = SSH_TUNMODE_POINTOPOINT;
 888                 else if (strcasecmp(arg, "yes") == 0)
 889                         value = SSH_TUNMODE_DEFAULT;
 890                 else if (strcasecmp(arg, "no") == 0)
 891                         value = SSH_TUNMODE_NO;
 892                 else
 893                         fatal("%s line %d: Bad yes/point-to-point/ethernet/"
 894                             "no argument: %s", filename, linenum, arg);
 895                 if (*activep)
 896                         *intptr = value;
 897                 break;
 898
 899         case oTunnelDevice:
 900                 arg = strdelim(&s);
 901                 if (!arg || *arg == '\0')
 902                         fatal("%.200s line %d: Missing argument.", filename, linenum);
 903                 value = a2tun(arg, &value2);
 904                 if (value == SSH_TUNID_ERR)
 905                         fatal("%.200s line %d: Bad tun device.", filename, linenum);
 906                 if (*activep) {
 907                         options->tun_local = value;
 908                         options->tun_remote = value2;
 909                 }
 910                 break;
 911
 912         case oLocalCommand:
 913                 charptr = &options->local_command;
 914                 goto parse_command;
 915
 916         case oPermitLocalCommand:
 917                 intptr = &options->permit_local_command;
 918                 goto parse_flag;
 919
 920         case oVisualHostKey:
 921                 intptr = &options->visual_host_key;
 922                 goto parse_flag;
 923
 924         case oDeprecated:
 925                 debug("%s line %d: Deprecated option \"%s\"",
 926                     filename, linenum, keyword);
 927                 return 0;
 928
 929         case oUnsupported:
 930                 error("%s line %d: Unsupported option \"%s\"",
 931                     filename, linenum, keyword);
 932                 return 0;
 933
 934         default:
 935                 fatal("process_config_line: Unimplemented opcode %d", opcode);
 936         }
 937
 938         /* Check that there is no garbage at end of line. */
 939         if ((arg = strdelim(&s)) != NULL && *arg != '\0') {
 940                 fatal("%.200s line %d: garbage at end of line; \"%.200s\".",
 941                     filename, linenum, arg);
 942         }
 943         return 0;
 944 }
 945
 946
 947 /*
 948  * Reads the config file and modifies the options accordingly.  Options
 949  * should already be initialized before this call.  This never returns if
 950  * there is an error.  If the file does not exist, this returns 0.
 951  */
 952
 953 int
 954 read_config_file(const char *filename, const char *host, Options *options,
 955     int checkperm)
 956 {
 957         FILE *f;
 958         char line[1024];
 959         int active, linenum;
 960         int bad_options = 0;
 961
 962         /* Open the file. */
 963         if ((f = fopen(filename, "r")) == NULL)
 964                 return 0;
 965
 966         if (checkperm) {
 967                 struct stat sb;
 968
 969                 if (fstat(fileno(f), &sb) == -1)
 970                         fatal("fstat %s: %s", filename, strerror(errno));
 971                 if (((sb.st_uid != 0 && sb.st_uid != getuid()) ||
 972                     (sb.st_mode & 022) != 0))
 973                         fatal("Bad owner or permissions on %s", filename);
 974         }
 975
 976         debug("Reading configuration data %.200s", filename);
 977
 978         /*
 979          * Mark that we are now processing the options.  This flag is turned
 980          * on/off by Host specifications.
 981          */
 982         active = 1;
 983         linenum = 0;
 984         while (fgets(line, sizeof(line), f)) {
 985                 /* Update line number counter. */
 986                 linenum++;
 987                 if (process_config_line(options, host, line, filename, linenum, &active) != 0)
 988                         bad_options++;
 989         }
 990         fclose(f);
 991         if (bad_options > 0)
 992                 fatal("%s: terminating, %d bad configuration options",
 993                     filename, bad_options);
 994         return 1;
 995 }
 996
 997 /*
 998  * Initializes options to special values that indicate that they have not yet
 999  * been set.  Read_config_file will only set options with this value. Options
1000  * are processed in the following order: command line, user config file,
1001  * system config file.  Last, fill_default_options is called.
1002  */
1003
1004 void
1005 initialize_options(Options * options)
1006 {
1007         memset(options, 'X', sizeof(*options));
1008         options->forward_agent = -1;
1009         options->forward_x11 = -1;
1010         options->forward_x11_trusted = -1;
1011         options->exit_on_forward_failure = -1;
1012         options->xauth_location = NULL;
1013         options->gateway_ports = -1;
1014         options->use_privileged_port = -1;
1015         options->rsa_authentication = -1;
1016         options->pubkey_authentication = -1;
1017         options->challenge_response_authentication = -1;
1018         options->gss_authentication = -1;
1019         options->gss_deleg_creds = -1;
1020         options->password_authentication = -1;
1021         options->kbd_interactive_authentication = -1;
1022         options->kbd_interactive_devices = NULL;
1023         options->rhosts_rsa_authentication = -1;
1024         options->hostbased_authentication = -1;
1025         options->batch_mode = -1;
1026         options->check_host_ip = -1;
1027         options->strict_host_key_checking = -1;
1028         options->compression = -1;
1029         options->tcp_keep_alive = -1;
1030         options->compression_level = -1;
1031         options->port = -1;
1032         options->address_family = -1;
1033         options->connection_attempts = -1;
1034         options->connection_timeout = -1;
1035         options->number_of_password_prompts = -1;
1036         options->cipher = -1;
1037         options->ciphers = NULL;
1038         options->macs = NULL;
1039         options->hostkeyalgorithms = NULL;
1040         options->protocol = SSH_PROTO_UNKNOWN;
1041         options->num_identity_files = 0;
1042         options->hostname = NULL;
1043         options->host_key_alias = NULL;
1044         options->proxy_command = NULL;
1045         options->user = NULL;
1046         options->escape_char = -1;
1047         options->system_hostfile = NULL;
1048         options->user_hostfile = NULL;
1049         options->system_hostfile2 = NULL;
1050         options->user_hostfile2 = NULL;
1051         options->num_local_forwards = 0;
1052         options->num_remote_forwards = 0;
1053         options->clear_forwardings = -1;
1054         options->log_level = SYSLOG_LEVEL_NOT_SET;
1055         options->preferred_authentications = NULL;
1056         options->bind_address = NULL;
1057         options->smartcard_device = NULL;
1058         options->enable_ssh_keysign = - 1;
1059         options->no_host_authentication_for_localhost = - 1;
1060         options->identities_only = - 1;
1061         options->rekey_limit = - 1;
1062         options->verify_host_key_dns = -1;
1063         options->server_alive_interval = -1;
1064         options->server_alive_count_max = -1;
1065         options->num_send_env = 0;
1066         options->control_path = NULL;
1067         options->control_master = -1;
1068         options->hash_known_hosts = -1;
1069         options->tun_open = -1;
1070         options->tun_local = -1;
1071         options->tun_remote = -1;
1072         options->local_command = NULL;
1073         options->permit_local_command = -1;
1074         options->visual_host_key = -1;
1075 }
1076
1077 /*
1078  * Called after processing other sources of option data, this fills those
1079  * options for which no value has been specified with their default values.
1080  */
1081
1082 void
1083 fill_default_options(Options * options)
1084 {
1085         int len;
1086
1087         if (options->forward_agent == -1)
1088                 options->forward_agent = 0;
1089         if (options->forward_x11 == -1)
1090                 options->forward_x11 = 0;
1091         if (options->forward_x11_trusted == -1)
1092                 options->forward_x11_trusted = 0;
1093         if (options->exit_on_forward_failure == -1)
1094                 options->exit_on_forward_failure = 0;
1095         if (options->xauth_location == NULL)
1096                 options->xauth_location = _PATH_XAUTH;
1097         if (options->gateway_ports == -1)
1098                 options->gateway_ports = 0;
1099         if (options->use_privileged_port == -1)
1100                 options->use_privileged_port = 0;
1101         if (options->rsa_authentication == -1)
1102                 options->rsa_authentication = 1;
1103         if (options->pubkey_authentication == -1)
1104                 options->pubkey_authentication = 1;
1105         if (options->challenge_response_authentication == -1)
1106                 options->challenge_response_authentication = 1;
1107         if (options->gss_authentication == -1)
1108                 options->gss_authentication = 0;
1109         if (options->gss_deleg_creds == -1)
1110                 options->gss_deleg_creds = 0;
1111         if (options->password_authentication == -1)
1112                 options->password_authentication = 1;
1113         if (options->kbd_interactive_authentication == -1)
1114                 options->kbd_interactive_authentication = 1;
1115         if (options->rhosts_rsa_authentication == -1)
1116                 options->rhosts_rsa_authentication = 0;
1117         if (options->hostbased_authentication == -1)
1118                 options->hostbased_authentication = 0;
1119         if (options->batch_mode == -1)
1120                 options->batch_mode = 0;
1121         if (options->check_host_ip == -1)
1122                 options->check_host_ip = 1;
1123         if (options->strict_host_key_checking == -1)
1124                 options->strict_host_key_checking = 2;  /* 2 is default */
1125         if (options->compression == -1)
1126                 options->compression = 0;
1127         if (options->tcp_keep_alive == -1)
1128                 options->tcp_keep_alive = 1;
1129         if (options->compression_level == -1)
1130                 options->compression_level = 6;
1131         if (options->port == -1)
1132                 options->port = 0;      /* Filled in ssh_connect. */
1133         if (options->address_family == -1)
1134                 options->address_family = AF_UNSPEC;
1135         if (options->connection_attempts == -1)
1136                 options->connection_attempts = 1;
1137         if (options->number_of_password_prompts == -1)
1138                 options->number_of_password_prompts = 3;
1139         /* Selected in ssh_login(). */
1140         if (options->cipher == -1)
1141                 options->cipher = SSH_CIPHER_NOT_SET;
1142         /* options->ciphers, default set in myproposals.h */
1143         /* options->macs, default set in myproposals.h */
1144         /* options->hostkeyalgorithms, default set in myproposals.h */
1145         if (options->protocol == SSH_PROTO_UNKNOWN)
1146                 options->protocol = SSH_PROTO_1|SSH_PROTO_2;
1147         if (options->num_identity_files == 0) {
1148                 if (options->protocol & SSH_PROTO_1) {
1149                         len = 2 + strlen(_PATH_SSH_CLIENT_IDENTITY) + 1;
1150                         options->identity_files[options->num_identity_files] =
1151                             xmalloc(len);
1152                         snprintf(options->identity_files[options->num_identity_files++],
1153                             len, "~/%.100s", _PATH_SSH_CLIENT_IDENTITY);
1154                 }
1155                 if (options->protocol & SSH_PROTO_2) {
1156                         len = 2 + strlen(_PATH_SSH_CLIENT_ID_RSA) + 1;
1157                         options->identity_files[options->num_identity_files] =
1158                             xmalloc(len);
1159                         snprintf(options->identity_files[options->num_identity_files++],
1160                             len, "~/%.100s", _PATH_SSH_CLIENT_ID_RSA);
1161
1162                         len = 2 + strlen(_PATH_SSH_CLIENT_ID_DSA) + 1;
1163                         options->identity_files[options->num_identity_files] =
1164                             xmalloc(len);
1165                         snprintf(options->identity_files[options->num_identity_files++],
1166                             len, "~/%.100s", _PATH_SSH_CLIENT_ID_DSA);
1167                 }
1168         }
1169         if (options->escape_char == -1)
1170                 options->escape_char = '~';
1171         if (options->system_hostfile == NULL)
1172                 options->system_hostfile = _PATH_SSH_SYSTEM_HOSTFILE;
1173         if (options->user_hostfile == NULL)
1174                 options->user_hostfile = _PATH_SSH_USER_HOSTFILE;
1175         if (options->system_hostfile2 == NULL)
1176                 options->system_hostfile2 = _PATH_SSH_SYSTEM_HOSTFILE2;
1177         if (options->user_hostfile2 == NULL)
1178                 options->user_hostfile2 = _PATH_SSH_USER_HOSTFILE2;
1179         if (options->log_level == SYSLOG_LEVEL_NOT_SET)
1180                 options->log_level = SYSLOG_LEVEL_INFO;
1181         if (options->clear_forwardings == 1)
1182                 clear_forwardings(options);
1183         if (options->no_host_authentication_for_localhost == - 1)
1184                 options->no_host_authentication_for_localhost = 0;
1185         if (options->identities_only == -1)
1186                 options->identities_only = 0;
1187         if (options->enable_ssh_keysign == -1)
1188                 options->enable_ssh_keysign = 0;
1189         if (options->rekey_limit == -1)
1190                 options->rekey_limit = 0;
1191         if (options->verify_host_key_dns == -1)
1192                 options->verify_host_key_dns = 0;
1193         if (options->server_alive_interval == -1)
1194                 options->server_alive_interval = 0;
1195         if (options->server_alive_count_max == -1)
1196                 options->server_alive_count_max = 3;
1197         if (options->control_master == -1)
1198                 options->control_master = 0;
1199         if (options->hash_known_hosts == -1)
1200                 options->hash_known_hosts = 0;
1201         if (options->tun_open == -1)
1202                 options->tun_open = SSH_TUNMODE_NO;
1203         if (options->tun_local == -1)
1204                 options->tun_local = SSH_TUNID_ANY;
1205         if (options->tun_remote == -1)
1206                 options->tun_remote = SSH_TUNID_ANY;
1207         if (options->permit_local_command == -1)
1208                 options->permit_local_command = 0;
1209         if (options->visual_host_key == -1)
1210                 options->visual_host_key = 0;
1211         /* options->local_command should not be set by default */
1212         /* options->proxy_command should not be set by default */
1213         /* options->user will be set in the main program if appropriate */
1214         /* options->hostname will be set in the main program if appropriate */
1215         /* options->host_key_alias should not be set by default */
1216         /* options->preferred_authentications will be set in ssh */
1217 }
1218
1219 /*
1220  * parse_forward
1221  * parses a string containing a port forwarding specification of the form:
1222  *      [listenhost:]listenport:connecthost:connectport
1223  * returns number of arguments parsed or zero on error
1224  */
1225 int
1226 parse_forward(Forward *fwd, const char *fwdspec)
1227 {
1228         int i;
1229         char *p, *cp, *fwdarg[4];
1230
1231         memset(fwd, '\0', sizeof(*fwd));
1232
1233         cp = p = xstrdup(fwdspec);
1234
1235         /* skip leading spaces */
1236         while (isspace(*cp))
1237                 cp++;
1238
1239         for (i = 0; i < 4; ++i)
1240                 if ((fwdarg[i] = hpdelim(&cp)) == NULL)
1241                         break;
1242
1243         /* Check for trailing garbage in 4-arg case*/
1244         if (cp != NULL)
1245                 i = 0;  /* failure */
1246
1247         switch (i) {
1248         case 3:
1249                 fwd->listen_host = NULL;
1250                 fwd->listen_port = a2port(fwdarg[0]);
1251                 fwd->connect_host = xstrdup(cleanhostname(fwdarg[1]));
1252                 fwd->connect_port = a2port(fwdarg[2]);
1253                 break;
1254
1255         case 4:
1256                 fwd->listen_host = xstrdup(cleanhostname(fwdarg[0]));
1257                 fwd->listen_port = a2port(fwdarg[1]);
1258                 fwd->connect_host = xstrdup(cleanhostname(fwdarg[2]));
1259                 fwd->connect_port = a2port(fwdarg[3]);
1260                 break;
1261         default:
1262                 i = 0; /* failure */
1263         }
1264
1265         xfree(p);
1266
1267         if (fwd->listen_port == 0 || fwd->connect_port == 0)
1268                 goto fail_free;
1269
1270         if (fwd->connect_host != NULL &&
1271             strlen(fwd->connect_host) >= NI_MAXHOST)
1272                 goto fail_free;
1273
1274         return (i);
1275
1276  fail_free:
1277         if (fwd->connect_host != NULL)
1278                 xfree(fwd->connect_host);
1279         if (fwd->listen_host != NULL)
1280                 xfree(fwd->listen_host);
1281         return (0);
1282 }