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