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 void pfd_log(Plug plug, int type, SockAddr addr, int port,
  90                     const char *error_msg, int error_code)
  91 {
  92     /* we have to dump these since we have no interface to logging.c */
  93 }
  94
  95 static int pfd_closing(Plug plug, const char *error_msg, int error_code,
  96                        int calling_back)
  97 {
  98     struct PFwdPrivate *pr = (struct PFwdPrivate *) plug;
  99
 100     /*
 101      * We have no way to communicate down the forwarded connection,
 102      * so if an error occurred on the socket, we just ignore it
 103      * and treat it like a proper close.
 104      */
 105     if (pr->c)
 106         sshfwd_close(pr->c);
 107     pfd_close(pr->s);
 108     return 1;
 109 }
 110
 111 static int pfd_receive(Plug plug, int urgent, char *data, int len)
 112 {
 113     struct PFwdPrivate *pr = (struct PFwdPrivate *) plug;
 114     if (pr->dynamic) {
 115         while (len--) {
 116             /*
 117              * Throughout SOCKS negotiation, "hostname" is re-used as a
 118              * random protocol buffer with "port" storing the length.
 119              */
 120             if (pr->port >= lenof(pr->hostname)) {
 121                 /* Request too long. */
 122                 if ((pr->dynamic >> 12) == 4) {
 123                     /* Send back a SOCKS 4 error before closing. */
 124                     char data[8];
 125                     memset(data, 0, sizeof(data));
 126                     data[1] = 91;      /* generic `request rejected' */
 127                     sk_write(pr->s, data, 8);
 128                 }
 129                 pfd_close(pr->s);
 130                 return 1;
 131             }
 132             pr->hostname[pr->port++] = *data++;
 133
 134             /*
 135              * Now check what's in the buffer to see if it's a
 136              * valid and complete message in the SOCKS exchange.
 137              */
 138             if ((pr->dynamic == 1 || (pr->dynamic >> 12) == 4) &&
 139                 pr->hostname[0] == 4) {
 140                 /*
 141                  * SOCKS 4.
 142                  */
 143                 if (pr->dynamic == 1)
 144                     pr->dynamic = 0x4000;
 145                 if (pr->port < 2) continue;/* don't have command code yet */
 146                 if (pr->hostname[1] != 1) {
 147                     /* Not CONNECT. */
 148                     /* Send back a SOCKS 4 error before closing. */
 149                     char data[8];
 150                     memset(data, 0, sizeof(data));
 151                     data[1] = 91;      /* generic `request rejected' */
 152                     sk_write(pr->s, data, 8);
 153                     pfd_close(pr->s);
 154                     return 1;
 155                 }
 156                 if (pr->port <= 8) continue; /* haven't started user/hostname */
 157                 if (pr->hostname[pr->port-1] != 0)
 158                     continue;          /* haven't _finished_ user/hostname */
 159                 /*
 160                  * Now we have a full SOCKS 4 request. Check it to
 161                  * see if it's a SOCKS 4A request.
 162                  */
 163                 if (pr->hostname[4] == 0 && pr->hostname[5] == 0 &&
 164                     pr->hostname[6] == 0 && pr->hostname[7] != 0) {
 165                     /*
 166                      * It's SOCKS 4A. So if we haven't yet
 167                      * collected the host name, we should continue
 168                      * waiting for data in order to do so; if we
 169                      * have, we can go ahead.
 170                      */
 171                     int len;
 172                     if (pr->dynamic == 0x4000) {
 173                         pr->dynamic = 0x4001;
 174                         pr->port = 8;      /* reset buffer to overwrite name */
 175                         continue;
 176                     }
 177                     pr->hostname[0] = 0;   /* reply version code */
 178                     pr->hostname[1] = 90;   /* request granted */
 179                     sk_write(pr->s, pr->hostname, 8);
 180                     len= pr->port - 8;
 181                     pr->port = GET_16BIT_MSB_FIRST(pr->hostname+2);
 182                     memmove(pr->hostname, pr->hostname + 8, len);
 183                     goto connect;
 184                 } else {
 185                     /*
 186                      * It's SOCKS 4, which means we should format
 187                      * the IP address into the hostname string and
 188                      * then just go.
 189                      */
 190                     pr->hostname[0] = 0;   /* reply version code */
 191                     pr->hostname[1] = 90;   /* request granted */
 192                     sk_write(pr->s, pr->hostname, 8);
 193                     pr->port = GET_16BIT_MSB_FIRST(pr->hostname+2);
 194                     sprintf(pr->hostname, "%d.%d.%d.%d",
 195                             (unsigned char)pr->hostname[4],
 196                             (unsigned char)pr->hostname[5],
 197                             (unsigned char)pr->hostname[6],
 198                             (unsigned char)pr->hostname[7]);
 199                     goto connect;
 200                 }
 201             }
 202
 203             if ((pr->dynamic == 1 || (pr->dynamic >> 12) == 5) &&
 204                 pr->hostname[0] == 5) {
 205                 /*
 206                  * SOCKS 5.
 207                  */
 208                 if (pr->dynamic == 1)
 209                     pr->dynamic = 0x5000;
 210
 211                 if (pr->dynamic == 0x5000) {
 212                     int i, method;
 213                     char data[2];
 214                     /*
 215                      * We're receiving a set of method identifiers.
 216                      */
 217                     if (pr->port < 2) continue;/* no method count yet */
 218                     if (pr->port < 2 + (unsigned char)pr->hostname[1])
 219                         continue;      /* no methods yet */
 220                     method = 0xFF;     /* invalid */
 221                     for (i = 0; i < (unsigned char)pr->hostname[1]; i++)
 222                         if (pr->hostname[2+i] == 0) {
 223                             method = 0;/* no auth */
 224                             break;
 225                         }
 226                     data[0] = 5;
 227                     data[1] = method;
 228                     sk_write(pr->s, data, 2);
 229                     pr->dynamic = 0x5001;
 230                     pr->port = 0;      /* re-empty the buffer */
 231                     continue;
 232                 }
 233
 234                 if (pr->dynamic == 0x5001) {
 235                     /*
 236                      * We're receiving a SOCKS request.
 237                      */
 238                     unsigned char reply[10]; /* SOCKS5 atyp=1 reply */
 239                     int atype, alen = 0;
 240
 241                     /*
 242                      * Pre-fill reply packet.
 243                      * In all cases, we set BND.{HOST,ADDR} to 0.0.0.0:0
 244                      * (atyp=1) in the reply; if we succeed, we don't know
 245                      * the right answers, and if we fail, they should be
 246                      * ignored.
 247                      */
 248                     memset(reply, 0, lenof(reply));
 249                     reply[0] = 5; /* VER */
 250                     reply[3] = 1; /* ATYP = 1 (IPv4, 0.0.0.0:0) */
 251
 252                     if (pr->port < 6) continue;
 253                     atype = (unsigned char)pr->hostname[3];
 254                     if (atype == 1)    /* IPv4 address */
 255                         alen = 4;
 256                     if (atype == 4)    /* IPv6 address */
 257                         alen = 16;
 258                     if (atype == 3)    /* domain name has leading length */
 259                         alen = 1 + (unsigned char)pr->hostname[4];
 260                     if (pr->port < 6 + alen) continue;
 261                     if (pr->hostname[1] != 1 || pr->hostname[2] != 0) {
 262                         /* Not CONNECT or reserved field nonzero - error */
 263                         reply[1] = 1;   /* generic failure */
 264                         sk_write(pr->s, (char *) reply, lenof(reply));
 265                         pfd_close(pr->s);
 266                         return 1;
 267                     }
 268                     /*
 269                      * Now we have a viable connect request. Switch
 270                      * on atype.
 271                      */
 272                     pr->port = GET_16BIT_MSB_FIRST(pr->hostname+4+alen);
 273                     if (atype == 1) {
 274                         /* REP=0 (success) already */
 275                         sk_write(pr->s, (char *) reply, lenof(reply));
 276                         sprintf(pr->hostname, "%d.%d.%d.%d",
 277                                 (unsigned char)pr->hostname[4],
 278                                 (unsigned char)pr->hostname[5],
 279                                 (unsigned char)pr->hostname[6],
 280                                 (unsigned char)pr->hostname[7]);
 281                         goto connect;
 282                     } else if (atype == 3) {
 283                         /* REP=0 (success) already */
 284                         sk_write(pr->s, (char *) reply, lenof(reply));
 285                         memmove(pr->hostname, pr->hostname + 5, alen-1);
 286                         pr->hostname[alen-1] = '\0';
 287                         goto connect;
 288                     } else {
 289                         /*
 290                          * Unknown address type. (FIXME: support IPv6!)
 291                          */
 292                         reply[1] = 8;   /* atype not supported */
 293                         sk_write(pr->s, (char *) reply, lenof(reply));
 294                         pfd_close(pr->s);
 295                         return 1;
 296                     }
 297                 }
 298             }
 299
 300             /*
 301              * If we get here without either having done `continue'
 302              * or `goto connect', it must be because there is no
 303              * sensible interpretation of what's in our buffer. So
 304              * close the connection rudely.
 305              */
 306             pfd_close(pr->s);
 307             return 1;
 308         }
 309         return 1;
 310
 311         /*
 312          * We come here when we're ready to make an actual
 313          * connection.
 314          */
 315         connect:
 316
 317         pr->c = new_sock_channel(pr->backhandle, pr->s);
 318         if (pr->c == NULL) {
 319             pfd_close(pr->s);
 320             return 1;
 321         } else {
 322             /* asks to forward to the specified host/port for this */
 323             ssh_send_port_open(pr->c, pr->hostname, pr->port, "forwarding");
 324         }
 325         pr->dynamic = 0;
 326
 327         /*
 328          * Now freeze the socket until the SSH server confirms the
 329          * connection.
 330          */
 331         sk_set_frozen(pr->s, 1);
 332         /*
 333          * If there's any data remaining in our current buffer,
 334          * save it to be sent on pfd_confirm().
 335          */
 336         if (len > 0) {
 337             pr->buffer = snewn(len, char);
 338             memcpy(pr->buffer, data, len);
 339             pr->buflen = len;
 340         }
 341     }
 342     if (pr->ready) {
 343         if (sshfwd_write(pr->c, data, len) > 0) {
 344             pr->throttled = 1;
 345             sk_set_frozen(pr->s, 1);
 346         }
 347     }
 348     return 1;
 349 }
 350
 351 static void pfd_sent(Plug plug, int bufsize)
 352 {
 353     struct PFwdPrivate *pr = (struct PFwdPrivate *) plug;
 354
 355     if (pr->c)
 356         sshfwd_unthrottle(pr->c, bufsize);
 357 }
 358
 359 /*
 360  * Called when receiving a PORT OPEN from the server
 361  */
 362 const char *pfd_newconnect(Socket *s, char *hostname, int port,
 363                            void *c, const Config *cfg, int addressfamily)
 364 {
 365     static const struct plug_function_table fn_table = {
 366         pfd_log,
 367         pfd_closing,
 368         pfd_receive,
 369         pfd_sent,
 370         NULL
 371     };
 372
 373     SockAddr addr;
 374     const char *err;
 375     char *dummy_realhost;
 376     struct PFwdPrivate *pr;
 377
 378     /*
 379      * Try to find host.
 380      */
 381     addr = name_lookup(hostname, port, &dummy_realhost, cfg, addressfamily);
 382     if ((err = sk_addr_error(addr)) != NULL) {
 383         sk_addr_free(addr);
 384         return err;
 385     }
 386
 387     /*
 388      * Open socket.
 389      */
 390     pr = snew(struct PFwdPrivate);
 391     pr->buffer = NULL;
 392     pr->fn = &fn_table;
 393     pr->throttled = pr->throttle_override = 0;
 394     pr->ready = 1;
 395     pr->c = c;
 396     pr->backhandle = NULL;             /* we shouldn't need this */
 397     pr->dynamic = 0;
 398
 399     pr->s = *s = new_connection(addr, dummy_realhost, port,
 400                                 0, 1, 0, 0, (Plug) pr, cfg);
 401     if ((err = sk_socket_error(*s)) != NULL) {
 402         sfree(pr);
 403         return err;
 404     }
 405
 406     sk_set_private_ptr(*s, pr);
 407     return NULL;
 408 }
 409
 410 /*
 411  called when someone connects to the local port
 412  */
 413
 414 static int pfd_accepting(Plug p, OSSocket sock)
 415 {
 416     static const struct plug_function_table fn_table = {
 417         pfd_log,
 418         pfd_closing,
 419         pfd_receive,
 420         pfd_sent,
 421         NULL
 422     };
 423     struct PFwdPrivate *pr, *org;
 424     Socket s;
 425     const char *err;
 426
 427     org = (struct PFwdPrivate *)p;
 428     pr = snew(struct PFwdPrivate);
 429     pr->buffer = NULL;
 430     pr->fn = &fn_table;
 431
 432     pr->c = NULL;
 433     pr->backhandle = org->backhandle;
 434
 435     pr->s = s = sk_register(sock, (Plug) pr);
 436     if ((err = sk_socket_error(s)) != NULL) {
 437         sfree(pr);
 438         return err != NULL;
 439     }
 440
 441     sk_set_private_ptr(s, pr);
 442
 443     pr->throttled = pr->throttle_override = 0;
 444     pr->ready = 0;
 445
 446     if (org->dynamic) {
 447         pr->dynamic = 1;
 448         pr->port = 0;                  /* "hostname" buffer is so far empty */
 449         sk_set_frozen(s, 0);           /* we want to receive SOCKS _now_! */
 450     } else {
 451         pr->dynamic = 0;
 452         strcpy(pr->hostname, org->hostname);
 453         pr->port = org->port;
 454         pr->c = new_sock_channel(org->backhandle, s);
 455
 456         if (pr->c == NULL) {
 457             sfree(pr);
 458             return 1;
 459         } else {
 460             /* asks to forward to the specified host/port for this */
 461             ssh_send_port_open(pr->c, pr->hostname, pr->port, "forwarding");
 462         }
 463     }
 464
 465     return 0;
 466 }
 467
 468
 469 /* Add a new forwarding from port -> desthost:destport
 470  sets up a listener on the local machine on (srcaddr:)port
 471  */
 472 const char *pfd_addforward(char *desthost, int destport, char *srcaddr,
 473                            int port, void *backhandle, const Config *cfg,
 474                            void **sockdata, int address_family)
 475 {
 476     static const struct plug_function_table fn_table = {
 477         pfd_log,
 478         pfd_closing,
 479         pfd_receive,                   /* should not happen... */
 480         pfd_sent,                      /* also should not happen */
 481         pfd_accepting
 482     };
 483
 484     const char *err;
 485     struct PFwdPrivate *pr;
 486     Socket s;
 487
 488     /*
 489      * Open socket.
 490      */
 491     pr = snew(struct PFwdPrivate);
 492     pr->buffer = NULL;
 493     pr->fn = &fn_table;
 494     pr->c = NULL;
 495     if (desthost) {
 496         strcpy(pr->hostname, desthost);
 497         pr->port = destport;
 498         pr->dynamic = 0;
 499     } else
 500         pr->dynamic = 1;
 501     pr->throttled = pr->throttle_override = 0;
 502     pr->ready = 0;
 503     pr->backhandle = backhandle;
 504
 505     pr->s = s = new_listener(srcaddr, port, (Plug) pr,
 506                              !cfg->lport_acceptall, cfg, address_family);
 507     if ((err = sk_socket_error(s)) != NULL) {
 508         sfree(pr);
 509         return err;
 510     }
 511
 512     sk_set_private_ptr(s, pr);
 513
 514     *sockdata = (void *)s;
 515
 516     return NULL;
 517 }
 518
 519 void pfd_close(Socket s)
 520 {
 521     struct PFwdPrivate *pr;
 522
 523     if (!s)
 524         return;
 525
 526     pr = (struct PFwdPrivate *) sk_get_private_ptr(s);
 527
 528     sfree(pr->buffer);
 529     sfree(pr);
 530
 531     sk_close(s);
 532 }
 533
 534 /*
 535  * Terminate a listener.
 536  */
 537 void pfd_terminate(void *sv)
 538 {
 539     pfd_close((Socket)sv);
 540 }
 541
 542 void pfd_unthrottle(Socket s)
 543 {
 544     struct PFwdPrivate *pr;
 545     if (!s)
 546         return;
 547     pr = (struct PFwdPrivate *) sk_get_private_ptr(s);
 548
 549     pr->throttled = 0;
 550     sk_set_frozen(s, pr->throttled || pr->throttle_override);
 551 }
 552
 553 void pfd_override_throttle(Socket s, int enable)
 554 {
 555     struct PFwdPrivate *pr;
 556     if (!s)
 557         return;
 558     pr = (struct PFwdPrivate *) sk_get_private_ptr(s);
 559
 560     pr->throttle_override = enable;
 561     sk_set_frozen(s, pr->throttled || pr->throttle_override);
 562 }
 563
 564 /*
 565  * Called to send data down the raw connection.
 566  */
 567 int pfd_send(Socket s, char *data, int len)
 568 {
 569     if (s == NULL)
 570         return 0;
 571     return sk_write(s, data, len);
 572 }
 573
 574
 575 void pfd_confirm(Socket s)
 576 {
 577     struct PFwdPrivate *pr;
 578
 579     if (s == NULL)
 580         return;
 581
 582     pr = (struct PFwdPrivate *) sk_get_private_ptr(s);
 583     pr->ready = 1;
 584     sk_set_frozen(s, 0);
 585     sk_write(s, NULL, 0);
 586     if (pr->buffer) {
 587         sshfwd_write(pr->c, pr->buffer, pr->buflen);
 588         sfree(pr->buffer);
 589         pr->buffer = NULL;
 590     }
 591 }