git.distorted.org.uk Git - u/mdw/putty/blob - portfwd.c

   1 #include <stdio.h>
   2 #include <stdlib.h>
   3
   4 #include "putty.h"
   5 #include "ssh.h"
   6
   7 #ifndef FALSE
   8 #define FALSE 0
   9 #endif
  10 #ifndef TRUE
  11 #define TRUE 1
  12 #endif
  13
  14 #define GET_32BIT_LSB_FIRST(cp) \
  15   (((unsigned long)(unsigned char)(cp)[0]) | \
  16   ((unsigned long)(unsigned char)(cp)[1] << 8) | \
  17   ((unsigned long)(unsigned char)(cp)[2] << 16) | \
  18   ((unsigned long)(unsigned char)(cp)[3] << 24))
  19
  20 #define PUT_32BIT_LSB_FIRST(cp, value) ( \
  21   (cp)[0] = (value), \
  22   (cp)[1] = (value) >> 8, \
  23   (cp)[2] = (value) >> 16, \
  24   (cp)[3] = (value) >> 24 )
  25
  26 #define GET_16BIT_LSB_FIRST(cp) \
  27   (((unsigned long)(unsigned char)(cp)[0]) | \
  28   ((unsigned long)(unsigned char)(cp)[1] << 8))
  29
  30 #define PUT_16BIT_LSB_FIRST(cp, value) ( \
  31   (cp)[0] = (value), \
  32   (cp)[1] = (value) >> 8 )
  33
  34 #define GET_32BIT_MSB_FIRST(cp) \
  35   (((unsigned long)(unsigned char)(cp)[0] << 24) | \
  36   ((unsigned long)(unsigned char)(cp)[1] << 16) | \
  37   ((unsigned long)(unsigned char)(cp)[2] << 8) | \
  38   ((unsigned long)(unsigned char)(cp)[3]))
  39
  40 #define PUT_32BIT_MSB_FIRST(cp, value) ( \
  41   (cp)[0] = (value) >> 24, \
  42   (cp)[1] = (value) >> 16, \
  43   (cp)[2] = (value) >> 8, \
  44   (cp)[3] = (value) )
  45
  46 #define GET_16BIT_MSB_FIRST(cp) \
  47   (((unsigned long)(unsigned char)(cp)[0] << 8) | \
  48   ((unsigned long)(unsigned char)(cp)[1]))
  49
  50 #define PUT_16BIT_MSB_FIRST(cp, value) ( \
  51   (cp)[0] = (value) >> 8, \
  52   (cp)[1] = (value) )
  53
  54 struct PFwdPrivate {
  55     const struct plug_function_table *fn;
  56     /* the above variable absolutely *must* be the first in this structure */
  57     void *c;                           /* (channel) data used by ssh.c */
  58     void *backhandle;                  /* instance of SSH backend itself */
  59     /* Note that backhandle need not be filled in if c is non-NULL */
  60     Socket s;
  61     int throttled, throttle_override;
  62     int ready;
  63     /*
  64      * `dynamic' does double duty. It's set to 0 for an ordinary
  65      * forwarded port, and nonzero for SOCKS-style dynamic port
  66      * forwarding; but it also represents the state of the SOCKS
  67      * exchange.
  68      */
  69     int dynamic;
  70     /*
  71      * `hostname' and `port' are the real hostname and port, once
  72      * we know what we're connecting to; they're unused for this
  73      * purpose while conducting a local SOCKS exchange, which means
  74      * we can also use them as a buffer and pointer for reading
  75      * data from the SOCKS client.
  76      */
  77     char hostname[256+8];
  78     int port;
  79     /*
  80      * When doing dynamic port forwarding, we can receive
  81      * connection data before we are actually able to send it; so
  82      * we may have to temporarily hold some in a dynamically
  83      * allocated buffer here.
  84      */
  85     void *buffer;
  86     int buflen;
  87 };
  88
  89 static int pfd_closing(Plug plug, char *error_msg, int error_code,
  90                        int calling_back)
  91 {
  92     struct PFwdPrivate *pr = (struct PFwdPrivate *) plug;
  93
  94     /*
  95      * We have no way to communicate down the forwarded connection,
  96      * so if an error occurred on the socket, we just ignore it
  97      * and treat it like a proper close.
  98      */
  99     if (pr->c)
 100         sshfwd_close(pr->c);
 101     pfd_close(pr->s);
 102     return 1;
 103 }
 104
 105 static int pfd_receive(Plug plug, int urgent, char *data, int len)
 106 {
 107     struct PFwdPrivate *pr = (struct PFwdPrivate *) plug;
 108     if (pr->dynamic) {
 109         while (len--) {
 110             if (pr->port >= lenof(pr->hostname)) {
 111                 if ((pr->dynamic >> 12) == 4) {
 112                     /* Send back a SOCKS 4 error before closing. */
 113                     char data[8];
 114                     memset(data, 0, sizeof(data));
 115                     data[1] = 91;      /* generic `request rejected' */
 116                     sk_write(pr->s, data, 8);
 117                 }
 118                 pfd_close(pr->s);
 119                 return 1;
 120             }
 121             pr->hostname[pr->port++] = *data++;
 122
 123             /*
 124              * Now check what's in the buffer to see if it's a
 125              * valid and complete message in the SOCKS exchange.
 126              */
 127             if ((pr->dynamic == 1 || (pr->dynamic >> 12) == 4) &&
 128                 pr->hostname[0] == 4) {
 129                 /*
 130                  * SOCKS 4.
 131                  */
 132                 if (pr->dynamic == 1)
 133                     pr->dynamic = 0x4000;
 134                 if (pr->port < 2) continue;/* don't have command code yet */
 135                 if (pr->hostname[1] != 1) {
 136                     /* Send back a SOCKS 4 error before closing. */
 137                     char data[8];
 138                     memset(data, 0, sizeof(data));
 139                     data[1] = 91;      /* generic `request rejected' */
 140                     sk_write(pr->s, data, 8);
 141                     pfd_close(pr->s);
 142                     return 1;
 143                 }
 144                 if (pr->port < 8) continue;   /* haven't started username */
 145                 if (pr->hostname[pr->port-1] != 0)
 146                     continue;          /* haven't _finished_ username */
 147                 /*
 148                  * Now we have a full SOCKS 4 request. Check it to
 149                  * see if it's a SOCKS 4A request.
 150                  */
 151                 if (pr->hostname[4] == 0 && pr->hostname[5] == 0 &&
 152                     pr->hostname[6] == 0 && pr->hostname[7] != 0) {
 153                     /*
 154                      * It's SOCKS 4A. So if we haven't yet
 155                      * collected the host name, we should continue
 156                      * waiting for data in order to do so; if we
 157                      * have, we can go ahead.
 158                      */
 159                     int len;
 160                     if (pr->dynamic == 0x4000) {
 161                         pr->dynamic = 0x4001;
 162                         pr->port = 8;      /* reset buffer to overwrite name */
 163                         continue;
 164                     }
 165                     pr->hostname[0] = 0;   /* reply version code */
 166                     pr->hostname[1] = 90;   /* request granted */
 167                     sk_write(pr->s, pr->hostname, 8);
 168                     len= pr->port;
 169                     pr->port = GET_16BIT_MSB_FIRST(pr->hostname+2);
 170                     memmove(pr->hostname, pr->hostname + 8, len);
 171                     goto connect;
 172                 } else {
 173                     /*
 174                      * It's SOCKS 4, which means we should format
 175                      * the IP address into the hostname string and
 176                      * then just go.
 177                      */
 178                     pr->hostname[0] = 0;   /* reply version code */
 179                     pr->hostname[1] = 90;   /* request granted */
 180                     sk_write(pr->s, pr->hostname, 8);
 181                     pr->port = GET_16BIT_MSB_FIRST(pr->hostname+2);
 182                     sprintf(pr->hostname, "%d.%d.%d.%d",
 183                             (unsigned char)pr->hostname[4],
 184                             (unsigned char)pr->hostname[5],
 185                             (unsigned char)pr->hostname[6],
 186                             (unsigned char)pr->hostname[7]);
 187                     goto connect;
 188                 }
 189             }
 190
 191             if ((pr->dynamic == 1 || (pr->dynamic >> 12) == 5) &&
 192                 pr->hostname[0] == 5) {
 193                 /*
 194                  * SOCKS 5.
 195                  */
 196                 if (pr->dynamic == 1)
 197                     pr->dynamic = 0x5000;
 198
 199                 if (pr->dynamic == 0x5000) {
 200                     int i, method;
 201                     char data[2];
 202                     /*
 203                      * We're receiving a set of method identifiers.
 204                      */
 205                     if (pr->port < 2) continue;/* no method count yet */
 206                     if (pr->port < 2 + (unsigned char)pr->hostname[1])
 207                         continue;      /* no methods yet */
 208                     method = 0xFF;     /* invalid */
 209                     for (i = 0; i < (unsigned char)pr->hostname[1]; i++)
 210                         if (pr->hostname[2+i] == 0) {
 211                             method = 0;/* no auth */
 212                             break;
 213                         }
 214                     data[0] = 5;
 215                     data[1] = method;
 216                     sk_write(pr->s, data, 2);
 217                     pr->dynamic = 0x5001;
 218                     pr->port = 0;      /* re-empty the buffer */
 219                     continue;
 220                 }
 221
 222                 if (pr->dynamic == 0x5001) {
 223                     int atype, alen;
 224                     if (pr->port < 6) continue;
 225                     atype = (unsigned char)pr->hostname[3];
 226                     if (atype == 1)    /* IPv4 address */
 227                         alen = 4;
 228                     if (atype == 4)    /* IPv6 address */
 229                         alen = 16;
 230                     if (atype == 3)    /* domain name has leading length */
 231                         alen = 1 + (unsigned char)pr->hostname[4];
 232                     if (pr->port < 6 + alen) continue;
 233                     if (pr->hostname[1] != 1 || pr->hostname[2] != 0) {
 234                         pr->hostname[1] = 1;   /* generic failure */
 235                         pr->hostname[2] = 0;   /* reserved */
 236                         sk_write(pr->s, pr->hostname, pr->port);
 237                         pfd_close(pr->s);
 238                         return 1;
 239                     }
 240                     /*
 241                      * Now we have a viable connect request. Switch
 242                      * on atype.
 243                      */
 244                     pr->port = GET_16BIT_MSB_FIRST(pr->hostname+4+alen);
 245                     if (atype == 1) {
 246                         pr->hostname[1] = 0;   /* succeeded */
 247                         sk_write(pr->s, pr->hostname, alen + 6);
 248                         sprintf(pr->hostname, "%d.%d.%d.%d",
 249                                 (unsigned char)pr->hostname[4],
 250                                 (unsigned char)pr->hostname[5],
 251                                 (unsigned char)pr->hostname[6],
 252                                 (unsigned char)pr->hostname[7]);
 253                         goto connect;
 254                     } else if (atype == 3) {
 255                         pr->hostname[1] = 0;   /* succeeded */
 256                         sk_write(pr->s, pr->hostname, alen + 6);
 257                         memmove(pr->hostname, pr->hostname + 5, alen-1);
 258                         pr->hostname[alen-1] = '\0';
 259                         goto connect;
 260                     } else {
 261                         /*
 262                          * Unknown address type. (FIXME: support IPv6!)
 263                          */
 264                         pr->hostname[1] = 8;   /* atype not supported */
 265                         sk_write(pr->s, pr->hostname, pr->port);
 266                         pfd_close(pr->s);
 267                         return 1;
 268                     }
 269                 }
 270             }
 271
 272             /*
 273              * If we get here without either having done `continue'
 274              * or `goto connect', it must be because there is no
 275              * sensible interpretation of what's in our buffer. So
 276              * close the connection rudely.
 277              */
 278             pfd_close(pr->s);
 279             return 1;
 280         }
 281         return 1;
 282
 283         /*
 284          * We come here when we're ready to make an actual
 285          * connection.
 286          */
 287         connect:
 288
 289         pr->c = new_sock_channel(pr->backhandle, pr->s);
 290         if (pr->c == NULL) {
 291             pfd_close(pr->s);
 292             return 1;
 293         } else {
 294             /* asks to forward to the specified host/port for this */
 295             ssh_send_port_open(pr->c, pr->hostname, pr->port, "forwarding");
 296         }
 297         pr->dynamic = 0;
 298
 299         /*
 300          * Now freeze the socket until the SSH server confirms the
 301          * connection.
 302          */
 303         sk_set_frozen(pr->s, 1);
 304         /*
 305          * If there's any data remaining in our current buffer,
 306          * save it to be sent on pfd_confirm().
 307          */
 308         if (len > 0) {
 309             pr->buffer = snewn(len, char);
 310             memcpy(pr->buffer, data, len);
 311             pr->buflen = len;
 312         }
 313     }
 314     if (pr->ready) {
 315         if (sshfwd_write(pr->c, data, len) > 0) {
 316             pr->throttled = 1;
 317             sk_set_frozen(pr->s, 1);
 318         }
 319     }
 320     return 1;
 321 }
 322
 323 static void pfd_sent(Plug plug, int bufsize)
 324 {
 325     struct PFwdPrivate *pr = (struct PFwdPrivate *) plug;
 326
 327     if (pr->c)
 328         sshfwd_unthrottle(pr->c, bufsize);
 329 }
 330
 331 /*
 332  * Called when receiving a PORT OPEN from the server
 333  */
 334 char *pfd_newconnect(Socket *s, char *hostname, int port, void *c,
 335                      const Config *cfg)
 336 {
 337     static const struct plug_function_table fn_table = {
 338         pfd_closing,
 339         pfd_receive,
 340         pfd_sent,
 341         NULL
 342     };
 343
 344     SockAddr addr;
 345     char *err, *dummy_realhost;
 346     struct PFwdPrivate *pr;
 347
 348     /*
 349      * Try to find host.
 350      */
 351     addr = name_lookup(hostname, port, &dummy_realhost, cfg);
 352     if ((err = sk_addr_error(addr)) != NULL)
 353         return err;
 354
 355     /*
 356      * Open socket.
 357      */
 358     pr = snew(struct PFwdPrivate);
 359     pr->buffer = NULL;
 360     pr->fn = &fn_table;
 361     pr->throttled = pr->throttle_override = 0;
 362     pr->ready = 1;
 363     pr->c = c;
 364     pr->backhandle = NULL;             /* we shouldn't need this */
 365     pr->dynamic = 0;
 366
 367     pr->s = *s = new_connection(addr, dummy_realhost, port,
 368                                 0, 1, 0, (Plug) pr, cfg);
 369     if ((err = sk_socket_error(*s)) != NULL) {
 370         sfree(pr);
 371         return err;
 372     }
 373
 374     sk_set_private_ptr(*s, pr);
 375     sk_addr_free(addr);
 376     return NULL;
 377 }
 378
 379 /*
 380  called when someone connects to the local port
 381  */
 382
 383 static int pfd_accepting(Plug p, void *sock)
 384 {
 385     static const struct plug_function_table fn_table = {
 386         pfd_closing,
 387         pfd_receive,
 388         pfd_sent,
 389         NULL
 390     };
 391     struct PFwdPrivate *pr, *org;
 392     Socket s;
 393     char *err;
 394
 395     org = (struct PFwdPrivate *)p;
 396     pr = snew(struct PFwdPrivate);
 397     pr->buffer = NULL;
 398     pr->fn = &fn_table;
 399
 400     pr->c = NULL;
 401     pr->backhandle = org->backhandle;
 402
 403     pr->s = s = sk_register(sock, (Plug) pr);
 404     if ((err = sk_socket_error(s)) != NULL) {
 405         sfree(pr);
 406         return err != NULL;
 407     }
 408
 409     sk_set_private_ptr(s, pr);
 410
 411     pr->throttled = pr->throttle_override = 0;
 412     pr->ready = 0;
 413
 414     if (org->dynamic) {
 415         pr->dynamic = 1;
 416         pr->port = 0;                  /* hostname buffer is so far empty */
 417         sk_set_frozen(s, 0);           /* we want to receive SOCKS _now_! */
 418     } else {
 419         pr->dynamic = 0;
 420         strcpy(pr->hostname, org->hostname);
 421         pr->port = org->port;
 422         pr->c = new_sock_channel(org->backhandle, s);
 423
 424         if (pr->c == NULL) {
 425             sfree(pr);
 426             return 1;
 427         } else {
 428             /* asks to forward to the specified host/port for this */
 429             ssh_send_port_open(pr->c, pr->hostname, pr->port, "forwarding");
 430         }
 431     }
 432
 433     return 0;
 434 }
 435
 436
 437 /* Add a new forwarding from port -> desthost:destport
 438  sets up a listener on the local machine on (srcaddr:)port
 439  */
 440 char *pfd_addforward(char *desthost, int destport, char *srcaddr, int port,
 441                      void *backhandle, const Config *cfg)
 442 {
 443     static const struct plug_function_table fn_table = {
 444         pfd_closing,
 445         pfd_receive,                   /* should not happen... */
 446         pfd_sent,                      /* also should not happen */
 447         pfd_accepting
 448     };
 449
 450     char *err;
 451     struct PFwdPrivate *pr;
 452     Socket s;
 453
 454     /*
 455      * Open socket.
 456      */
 457     pr = snew(struct PFwdPrivate);
 458     pr->buffer = NULL;
 459     pr->fn = &fn_table;
 460     pr->c = NULL;
 461     if (desthost) {
 462         strcpy(pr->hostname, desthost);
 463         pr->port = destport;
 464         pr->dynamic = 0;
 465     } else
 466         pr->dynamic = 1;
 467     pr->throttled = pr->throttle_override = 0;
 468     pr->ready = 0;
 469     pr->backhandle = backhandle;
 470
 471     pr->s = s = new_listener(srcaddr, port, (Plug) pr,
 472                              !cfg->lport_acceptall, cfg);
 473     if ((err = sk_socket_error(s)) != NULL) {
 474         sfree(pr);
 475         return err;
 476     }
 477
 478     sk_set_private_ptr(s, pr);
 479
 480     return NULL;
 481 }
 482
 483 void pfd_close(Socket s)
 484 {
 485     struct PFwdPrivate *pr;
 486
 487     if (!s)
 488         return;
 489
 490     pr = (struct PFwdPrivate *) sk_get_private_ptr(s);
 491
 492     sfree(pr->buffer);
 493     sfree(pr);
 494
 495     sk_close(s);
 496 }
 497
 498 void pfd_unthrottle(Socket s)
 499 {
 500     struct PFwdPrivate *pr;
 501     if (!s)
 502         return;
 503     pr = (struct PFwdPrivate *) sk_get_private_ptr(s);
 504
 505     pr->throttled = 0;
 506     sk_set_frozen(s, pr->throttled || pr->throttle_override);
 507 }
 508
 509 void pfd_override_throttle(Socket s, int enable)
 510 {
 511     struct PFwdPrivate *pr;
 512     if (!s)
 513         return;
 514     pr = (struct PFwdPrivate *) sk_get_private_ptr(s);
 515
 516     pr->throttle_override = enable;
 517     sk_set_frozen(s, pr->throttled || pr->throttle_override);
 518 }
 519
 520 /*
 521  * Called to send data down the raw connection.
 522  */
 523 int pfd_send(Socket s, char *data, int len)
 524 {
 525     if (s == NULL)
 526         return 0;
 527     return sk_write(s, data, len);
 528 }
 529
 530
 531 void pfd_confirm(Socket s)
 532 {
 533     struct PFwdPrivate *pr;
 534
 535     if (s == NULL)
 536         return;
 537
 538     pr = (struct PFwdPrivate *) sk_get_private_ptr(s);
 539     pr->ready = 1;
 540     sk_set_frozen(s, 0);
 541     sk_write(s, NULL, 0);
 542     if (pr->buffer) {
 543         sshfwd_write(pr->c, pr->buffer, pr->buflen);
 544         sfree(pr->buffer);
 545         pr->buffer = NULL;
 546     }
 547 }