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

   1 #include <stdio.h>
   2 #include <stdlib.h>
   3 #include <winsock.h>
   4
   5 #include "putty.h"
   6
   7 #ifndef FALSE
   8 #define FALSE 0
   9 #endif
  10 #ifndef TRUE
  11 #define TRUE 1
  12 #endif
  13
  14 #include "ssh.h"
  15
  16 /* Coroutine mechanics for the sillier bits of the code */
  17 #define crBegin1        static int crLine = 0;
  18 #define crBegin2        switch(crLine) { case 0:;
  19 #define crBegin         crBegin1; crBegin2;
  20 #define crFinish(z)     } crLine = 0; return (z)
  21 #define crFinishV       } crLine = 0; return
  22 #define crReturn(z)     \
  23         do {\
  24             crLine=__LINE__; return (z); case __LINE__:;\
  25         } while (0)
  26 #define crReturnV       \
  27         do {\
  28             crLine=__LINE__; return; case __LINE__:;\
  29         } while (0)
  30 #define crStop(z)       do{ crLine = 0; return (z); }while(0)
  31 #define crStopV         do{ crLine = 0; return; }while(0)
  32
  33 #ifndef FALSE
  34 #define FALSE 0
  35 #endif
  36 #ifndef TRUE
  37 #define TRUE 1
  38 #endif
  39
  40 static SOCKET s = INVALID_SOCKET;
  41
  42 static unsigned char session_key[32];
  43 static struct ssh_cipher *cipher = NULL;
  44
  45 static char *savedhost;
  46
  47 static enum {
  48     SSH_STATE_BEFORE_SIZE,
  49     SSH_STATE_INTERMED,
  50     SSH_STATE_SESSION,
  51     SSH_STATE_CLOSED
  52 } ssh_state = SSH_STATE_BEFORE_SIZE;
  53
  54 static int size_needed = FALSE;
  55
  56 static void s_write (char *buf, int len) {
  57     while (len > 0) {
  58         int i = send (s, buf, len, 0);
  59         if (i > 0)
  60             len -= i, buf += i;
  61     }
  62 }
  63
  64 static int s_read (char *buf, int len) {
  65     int ret = 0;
  66     while (len > 0) {
  67         int i = recv (s, buf, len, 0);
  68         if (i > 0)
  69             len -= i, buf += i, ret += i;
  70         else
  71             return i;
  72     }
  73     return ret;
  74 }
  75
  76 static void c_write (char *buf, int len) {
  77     while (len--) {
  78         int new_head = (inbuf_head + 1) & INBUF_MASK;
  79         if (new_head != inbuf_reap) {
  80             inbuf[inbuf_head] = *buf++;
  81             inbuf_head = new_head;
  82         }
  83     }
  84 }
  85
  86 struct Packet {
  87     long length;
  88     int type;
  89     unsigned long crc;
  90     unsigned char *data;
  91     unsigned char *body;
  92     long maxlen;
  93 };
  94
  95 static struct Packet pktin = { 0, 0, 0, NULL, 0 };
  96 static struct Packet pktout = { 0, 0, 0, NULL, 0 };
  97
  98 static void ssh_protocol(unsigned char *in, int inlen, int ispkt);
  99 static void ssh_size(void);
 100
 101 static void ssh_gotdata(unsigned char *data, int datalen) {
 102     static long len, biglen, to_read;
 103     static unsigned char *p;
 104     static int i, pad;
 105
 106     crBegin;
 107     while (1) {
 108         for (i = len = 0; i < 4; i++) {
 109             while (datalen == 0)
 110                 crReturnV;
 111             len = (len << 8) + *data;
 112             data++, datalen--;
 113         }
 114
 115 #ifdef FWHACK
 116         if (len == 0x52656d6f) {       /* "Remo"te server has closed ... */
 117             len = 0x300;               /* big enough to carry to end */
 118         }
 119 #endif
 120
 121         pad = 8 - (len%8);
 122
 123         biglen = len + pad;
 124
 125         len -= 5;                      /* type and CRC */
 126
 127         pktin.length = len;
 128         if (pktin.maxlen < biglen) {
 129             pktin.maxlen = biglen;
 130             pktin.data = (pktin.data == NULL ? malloc(biglen) :
 131                         realloc(pktin.data, biglen));
 132             if (!pktin.data)
 133                 fatalbox("Out of memory");
 134         }
 135
 136         p = pktin.data, to_read = biglen;
 137         while (to_read > 0) {
 138             static int chunk;
 139             chunk = to_read;
 140             while (datalen == 0)
 141                 crReturnV;
 142             if (chunk > datalen)
 143                 chunk = datalen;
 144             memcpy(p, data, chunk);
 145             data += chunk;
 146             datalen -= chunk;
 147             p += chunk;
 148             to_read -= chunk;
 149         }
 150
 151         if (cipher)
 152             cipher->decrypt(pktin.data, biglen);
 153
 154         pktin.type = pktin.data[pad];
 155         pktin.body = pktin.data+pad+1;
 156
 157         if (pktin.type == 36) {        /* SSH_MSG_DEBUG */
 158             /* FIXME: log it */
 159         } else
 160             ssh_protocol(NULL, 0, 1);
 161     }
 162     crFinishV;
 163 }
 164
 165 static void s_wrpkt_start(int type, int len) {
 166     int pad, biglen;
 167
 168     len += 5;                          /* type and CRC */
 169     pad = 8 - (len%8);
 170     biglen = len + pad;
 171
 172     pktout.length = len-5;
 173     if (pktout.maxlen < biglen) {
 174         pktout.maxlen = biglen;
 175         pktout.data = (pktout.data == NULL ? malloc(biglen+4) :
 176                        realloc(pktout.data, biglen+4));
 177         if (!pktout.data)
 178             fatalbox("Out of memory");
 179     }
 180
 181     pktout.type = type;
 182     pktout.body = pktout.data+4+pad+1;
 183 }
 184
 185 static void s_wrpkt(void) {
 186     int pad, len, biglen, i;
 187     unsigned long crc;
 188
 189     len = pktout.length + 5;           /* type and CRC */
 190     pad = 8 - (len%8);
 191     biglen = len + pad;
 192
 193     pktout.body[-1] = pktout.type;
 194     for (i=0; i<pad; i++)
 195         pktout.data[i+4] = random_byte();
 196     crc = crc32(pktout.data+4, biglen-4);
 197
 198     pktout.data[biglen+0] = (unsigned char) ((crc >> 24) & 0xFF);
 199     pktout.data[biglen+1] = (unsigned char) ((crc >> 16) & 0xFF);
 200     pktout.data[biglen+2] = (unsigned char) ((crc >> 8) & 0xFF);
 201     pktout.data[biglen+3] = (unsigned char) (crc & 0xFF);
 202
 203     pktout.data[0] = (len >> 24) & 0xFF;
 204     pktout.data[1] = (len >> 16) & 0xFF;
 205     pktout.data[2] = (len >> 8) & 0xFF;
 206     pktout.data[3] = len & 0xFF;
 207
 208     if (cipher)
 209         cipher->encrypt(pktout.data+4, biglen);
 210
 211     s_write(pktout.data, biglen+4);
 212 }
 213
 214 static int do_ssh_init(void) {
 215     char c;
 216     char version[10];
 217     char vstring[40];
 218     int i;
 219
 220 #ifdef FWHACK
 221     i = 0;
 222     while (s_read(&c, 1) == 1) {
 223         if (c == 'S' && i < 2) i++;
 224         else if (c == 'S' && i == 2) i = 2;
 225         else if (c == 'H' && i == 2) break;
 226         else i = 0;
 227     }
 228 #else
 229     if (s_read(&c,1) != 1 || c != 'S') return 0;
 230     if (s_read(&c,1) != 1 || c != 'S') return 0;
 231     if (s_read(&c,1) != 1 || c != 'H') return 0;
 232 #endif
 233     if (s_read(&c,1) != 1 || c != '-') return 0;
 234     i = 0;
 235     while (1) {
 236         if (s_read(&c,1) != 1)
 237             return 0;
 238         if (i >= 0) {
 239             if (c == '-') {
 240                 version[i] = '\0';
 241                 i = -1;
 242             } else if (i < sizeof(version)-1)
 243                 version[i++] = c;
 244         }
 245         else if (c == '\n')
 246             break;
 247     }
 248
 249     sprintf(vstring, "SSH-%s-7.7.7\n",
 250             (strcmp(version, "1.5") <= 0 ? version : "1.5"));
 251     s_write(vstring, strlen(vstring));
 252     return 1;
 253 }
 254
 255 static void ssh_protocol(unsigned char *in, int inlen, int ispkt) {
 256     int i, j, len;
 257     unsigned char session_id[16];
 258     unsigned char *rsabuf, *keystr1, *keystr2;
 259     unsigned char cookie[8];
 260     struct RSAKey servkey, hostkey;
 261     struct MD5Context md5c;
 262     unsigned long supported_ciphers_mask;
 263     int cipher_type;
 264
 265     extern struct ssh_cipher ssh_3des;
 266     extern struct ssh_cipher ssh_blowfish;
 267
 268     crBegin;
 269
 270     random_init();
 271
 272     while (!ispkt)
 273         crReturnV;
 274
 275     if (pktin.type != 2)
 276         fatalbox("Public key packet not received");
 277
 278     memcpy(cookie, pktin.body, 8);
 279
 280     MD5Init(&md5c);
 281
 282     i = makekey(pktin.body+8, &servkey, &keystr1);
 283
 284     j = makekey(pktin.body+8+i, &hostkey, &keystr2);
 285
 286     supported_ciphers_mask = (pktin.body[12+i+j] << 24) |
 287                              (pktin.body[13+i+j] << 16) |
 288                              (pktin.body[14+i+j] << 8) |
 289                              (pktin.body[15+i+j]);
 290
 291     MD5Update(&md5c, keystr2, hostkey.bytes);
 292     MD5Update(&md5c, keystr1, servkey.bytes);
 293     MD5Update(&md5c, pktin.body, 8);
 294
 295     MD5Final(session_id, &md5c);
 296
 297     for (i=0; i<32; i++)
 298         session_key[i] = random_byte();
 299
 300     len = (hostkey.bytes > servkey.bytes ? hostkey.bytes : servkey.bytes);
 301
 302     rsabuf = malloc(len);
 303     if (!rsabuf)
 304         fatalbox("Out of memory");
 305
 306     verify_ssh_host_key(savedhost, &hostkey);
 307
 308     for (i=0; i<32; i++) {
 309         rsabuf[i] = session_key[i];
 310         if (i < 16)
 311             rsabuf[i] ^= session_id[i];
 312     }
 313
 314     if (hostkey.bytes > servkey.bytes) {
 315         rsaencrypt(rsabuf, 32, &servkey);
 316         rsaencrypt(rsabuf, servkey.bytes, &hostkey);
 317     } else {
 318         rsaencrypt(rsabuf, 32, &hostkey);
 319         rsaencrypt(rsabuf, hostkey.bytes, &servkey);
 320     }
 321
 322     cipher_type = cfg.cipher == CIPHER_BLOWFISH ? SSH_CIPHER_BLOWFISH :
 323                   SSH_CIPHER_3DES;
 324     if ((supported_ciphers_mask & (1 << cipher_type)) == 0) {
 325         c_write("Selected cipher not supported, falling back to 3DES\r\n", 53);
 326         cipher_type = SSH_CIPHER_3DES;
 327     }
 328
 329     s_wrpkt_start(3, len+15);
 330     pktout.body[0] = cipher_type;
 331     memcpy(pktout.body+1, cookie, 8);
 332     pktout.body[9] = (len*8) >> 8;
 333     pktout.body[10] = (len*8) & 0xFF;
 334     memcpy(pktout.body+11, rsabuf, len);
 335     pktout.body[len+11] = pktout.body[len+12] = 0;   /* protocol flags */
 336     pktout.body[len+13] = pktout.body[len+14] = 0;
 337     s_wrpkt();
 338
 339     free(rsabuf);
 340
 341     cipher = cipher_type == SSH_CIPHER_BLOWFISH ? &ssh_blowfish :
 342              &ssh_3des;
 343     cipher->sesskey(session_key);
 344
 345     do { crReturnV; } while (!ispkt);
 346
 347     if (pktin.type != 14)
 348         fatalbox("Encryption not successfully enabled");
 349
 350     fflush(stdout);
 351     {
 352         static char username[100];
 353         static int pos = 0;
 354         static char c;
 355         if (!*cfg.username) {
 356             c_write("login as: ", 10);
 357             while (pos >= 0) {
 358                 do { crReturnV; } while (ispkt);
 359                 while (inlen--) switch (c = *in++) {
 360                   case 10: case 13:
 361                     username[pos] = 0;
 362                     pos = -1;
 363                     break;
 364                   case 8: case 127:
 365                     if (pos > 0) {
 366                         c_write("\b \b", 3);
 367                         pos--;
 368                     }
 369                     break;
 370                   case 21: case 27:
 371                     while (pos > 0) {
 372                         c_write("\b \b", 3);
 373                         pos--;
 374                     }
 375                     break;
 376                   case 3: case 4:
 377                     random_save_seed();
 378                     exit(0);
 379                     break;
 380                   default:
 381                     if (c >= ' ' && c <= '~' && pos < 40) {
 382                         username[pos++] = c;
 383                         c_write(&c, 1);
 384                     }
 385                     break;
 386                 }
 387             }
 388             c_write("\r\n", 2);
 389             username[strcspn(username, "\n\r")] = '\0';
 390         } else {
 391             char stuff[200];
 392             strncpy(username, cfg.username, 99);
 393             username[99] = '\0';
 394             sprintf(stuff, "Sent username \"%s\".\r\n", username);
 395             c_write(stuff, strlen(stuff));
 396         }
 397         s_wrpkt_start(4, 4+strlen(username));
 398         pktout.body[0] = pktout.body[1] = pktout.body[2] = 0;
 399         pktout.body[3] = strlen(username);
 400         memcpy(pktout.body+4, username, strlen(username));
 401         s_wrpkt();
 402     }
 403
 404     do { crReturnV; } while (!ispkt);
 405
 406     while (pktin.type == 15) {
 407         static char password[100];
 408         static int pos;
 409         static char c;
 410         c_write("password: ", 10);
 411         pos = 0;
 412         while (pos >= 0) {
 413             do { crReturnV; } while (ispkt);
 414             while (inlen--) switch (c = *in++) {
 415               case 10: case 13:
 416                 password[pos] = 0;
 417                 pos = -1;
 418                 break;
 419               case 8: case 127:
 420                 if (pos > 0)
 421                     pos--;
 422                 break;
 423               case 21: case 27:
 424                 pos = 0;
 425                 break;
 426               case 3: case 4:
 427                 random_save_seed();
 428                 exit(0);
 429                 break;
 430               default:
 431                 if (c >= ' ' && c <= '~' && pos < 40)
 432                     password[pos++] = c;
 433                 break;
 434             }
 435         }
 436         c_write("\r\n", 2);
 437         s_wrpkt_start(9, 4+strlen(password));
 438         pktout.body[0] = pktout.body[1] = pktout.body[2] = 0;
 439         pktout.body[3] = strlen(password);
 440         memcpy(pktout.body+4, password, strlen(password));
 441         s_wrpkt();
 442         memset(password, 0, strlen(password));
 443         do { crReturnV; } while (!ispkt);
 444         if (pktin.type == 15) {
 445             c_write("Access denied\r\n", 15);
 446         } else if (pktin.type != 14) {
 447             fatalbox("Strange packet received, type %d", pktin.type);
 448         }
 449     }
 450
 451     if (!cfg.nopty) {
 452         i = strlen(cfg.termtype);
 453         s_wrpkt_start(10, i+5*4+1);
 454         pktout.body[0] = (i >> 24) & 0xFF;
 455         pktout.body[1] = (i >> 16) & 0xFF;
 456         pktout.body[2] = (i >> 8) & 0xFF;
 457         pktout.body[3] = i & 0xFF;
 458         memcpy(pktout.body+4, cfg.termtype, i);
 459         i += 4;
 460         pktout.body[i++] = (rows >> 24) & 0xFF;
 461         pktout.body[i++] = (rows >> 16) & 0xFF;
 462         pktout.body[i++] = (rows >> 8) & 0xFF;
 463         pktout.body[i++] = rows & 0xFF;
 464         pktout.body[i++] = (cols >> 24) & 0xFF;
 465         pktout.body[i++] = (cols >> 16) & 0xFF;
 466         pktout.body[i++] = (cols >> 8) & 0xFF;
 467         pktout.body[i++] = cols & 0xFF;
 468         memset(pktout.body+i, 0, 9);       /* 0 pixwidth, 0 pixheight, 0.b endofopt */
 469         s_wrpkt();
 470         ssh_state = SSH_STATE_INTERMED;
 471         do { crReturnV; } while (!ispkt);
 472         if (pktin.type != 14 && pktin.type != 15) {
 473             fatalbox("Protocol confusion");
 474         } else if (pktin.type == 15) {
 475             c_write("Server refused to allocate pty\r\n", 32);
 476         }
 477     }
 478
 479     s_wrpkt_start(12, 0);
 480     s_wrpkt();
 481
 482     ssh_state = SSH_STATE_SESSION;
 483     if (size_needed)
 484         ssh_size();
 485
 486     while (1) {
 487         crReturnV;
 488         if (ispkt) {
 489             if (pktin.type == 17 || pktin.type == 18) {
 490                 long len = 0;
 491                 for (i = 0; i < 4; i++)
 492                     len = (len << 8) + pktin.body[i];
 493                 c_write(pktin.body+4, len);
 494             } else if (pktin.type == 1) {
 495                 /* SSH_MSG_DISCONNECT */
 496                 ssh_state = SSH_STATE_CLOSED;
 497             } else if (pktin.type == 14) {
 498                 /* SSH_MSG_SUCCESS: may be from EXEC_SHELL on some servers */
 499             } else if (pktin.type == 15) {
 500                 /* SSH_MSG_FAILURE: may be from EXEC_SHELL on some servers
 501                  * if no pty is available or in other odd cases. Ignore */
 502             } else if (pktin.type == 20) {
 503                 /* EXITSTATUS */
 504                 s_wrpkt_start(33, 0);
 505                 s_wrpkt();
 506             } else {
 507                 fatalbox("Strange packet received: type %d", pktin.type);
 508             }
 509         } else {
 510             s_wrpkt_start(16, 4+inlen);
 511             pktout.body[0] = (inlen >> 24) & 0xFF;
 512             pktout.body[1] = (inlen >> 16) & 0xFF;
 513             pktout.body[2] = (inlen >> 8) & 0xFF;
 514             pktout.body[3] = inlen & 0xFF;
 515             memcpy(pktout.body+4, in, inlen);
 516             s_wrpkt();
 517         }
 518     }
 519
 520     crFinishV;
 521 }
 522
 523 /*
 524  * Called to set up the connection. Will arrange for WM_NETEVENT
 525  * messages to be passed to the specified window, whose window
 526  * procedure should then call telnet_msg().
 527  *
 528  * Returns an error message, or NULL on success.
 529  *
 530  * Also places the canonical host name into `realhost'.
 531  */
 532 static char *ssh_init (HWND hwnd, char *host, int port, char **realhost) {
 533     SOCKADDR_IN addr;
 534     struct hostent *h;
 535     unsigned long a;
 536 #ifdef FWHACK
 537     char *FWhost;
 538     int FWport;
 539 #endif
 540
 541     savedhost = malloc(1+strlen(host));
 542     if (!savedhost)
 543         fatalbox("Out of memory");
 544     strcpy(savedhost, host);
 545
 546 #ifdef FWHACK
 547     FWhost = host;
 548     FWport = port;
 549     host = FWSTR;
 550     port = 23;
 551 #endif
 552
 553     /*
 554      * Try to find host.
 555      */
 556     if ( (a = inet_addr(host)) == (unsigned long) INADDR_NONE) {
 557         if ( (h = gethostbyname(host)) == NULL)
 558             switch (WSAGetLastError()) {
 559               case WSAENETDOWN: return "Network is down";
 560               case WSAHOST_NOT_FOUND: case WSANO_DATA:
 561                 return "Host does not exist";
 562               case WSATRY_AGAIN: return "Host not found";
 563               default: return "gethostbyname: unknown error";
 564             }
 565         memcpy (&a, h->h_addr, sizeof(a));
 566         *realhost = h->h_name;
 567     } else
 568         *realhost = host;
 569 #ifdef FWHACK
 570     *realhost = FWhost;
 571 #endif
 572     a = ntohl(a);
 573
 574     if (port < 0)
 575         port = 22;                     /* default ssh port */
 576
 577     /*
 578      * Open socket.
 579      */
 580     s = socket(AF_INET, SOCK_STREAM, 0);
 581     if (s == INVALID_SOCKET)
 582         switch (WSAGetLastError()) {
 583           case WSAENETDOWN: return "Network is down";
 584           case WSAEAFNOSUPPORT: return "TCP/IP support not present";
 585           default: return "socket(): unknown error";
 586         }
 587
 588     /*
 589      * Bind to local address.
 590      */
 591     addr.sin_family = AF_INET;
 592     addr.sin_addr.s_addr = htonl(INADDR_ANY);
 593     addr.sin_port = htons(0);
 594     if (bind (s, (struct sockaddr *)&addr, sizeof(addr)) == SOCKET_ERROR)
 595         switch (WSAGetLastError()) {
 596           case WSAENETDOWN: return "Network is down";
 597           default: return "bind(): unknown error";
 598         }
 599
 600     /*
 601      * Connect to remote address.
 602      */
 603     addr.sin_addr.s_addr = htonl(a);
 604     addr.sin_port = htons((short)port);
 605     if (connect (s, (struct sockaddr *)&addr, sizeof(addr)) == SOCKET_ERROR)
 606         switch (WSAGetLastError()) {
 607           case WSAENETDOWN: return "Network is down";
 608           case WSAECONNREFUSED: return "Connection refused";
 609           case WSAENETUNREACH: return "Network is unreachable";
 610           case WSAEHOSTUNREACH: return "No route to host";
 611           default: return "connect(): unknown error";
 612         }
 613
 614 #ifdef FWHACK
 615     send(s, "connect ", 8, 0);
 616     send(s, FWhost, strlen(FWhost), 0);
 617     {
 618         char buf[20];
 619         sprintf(buf, " %d\n", FWport);
 620         send (s, buf, strlen(buf), 0);
 621     }
 622 #endif
 623
 624     if (!do_ssh_init())
 625         return "Protocol initialisation error";
 626
 627     if (WSAAsyncSelect (s, hwnd, WM_NETEVENT, FD_READ | FD_CLOSE) == SOCKET_ERROR)
 628         switch (WSAGetLastError()) {
 629           case WSAENETDOWN: return "Network is down";
 630           default: return "WSAAsyncSelect(): unknown error";
 631         }
 632
 633     return NULL;
 634 }
 635
 636 /*
 637  * Process a WM_NETEVENT message. Will return 0 if the connection
 638  * has closed, or <0 for a socket error.
 639  */
 640 static int ssh_msg (WPARAM wParam, LPARAM lParam) {
 641     int ret;
 642     char buf[256];
 643
 644     if (s == INVALID_SOCKET)           /* how the hell did we get here?! */
 645         return -5000;
 646
 647     if (WSAGETSELECTERROR(lParam) != 0)
 648         return -WSAGETSELECTERROR(lParam);
 649
 650     switch (WSAGETSELECTEVENT(lParam)) {
 651       case FD_READ:
 652         ret = recv(s, buf, sizeof(buf), 0);
 653         if (ret < 0 && WSAGetLastError() == WSAEWOULDBLOCK)
 654             return 1;
 655         if (ret < 0)                   /* any _other_ error */
 656             return -10000-WSAGetLastError();
 657         if (ret == 0) {
 658             s = INVALID_SOCKET;
 659             return 0;                  /* can't happen, in theory */
 660         }
 661         ssh_gotdata (buf, ret);
 662         return 1;
 663       case FD_CLOSE:
 664         s = INVALID_SOCKET;
 665         ssh_state = SSH_STATE_CLOSED;
 666         return 0;
 667     }
 668     return 1;                          /* shouldn't happen, but WTF */
 669 }
 670
 671 /*
 672  * Called to send data down the Telnet connection.
 673  */
 674 static void ssh_send (char *buf, int len) {
 675     if (s == INVALID_SOCKET)
 676         return;
 677
 678     ssh_protocol(buf, len, 0);
 679 }
 680
 681 /*
 682  * Called to set the size of the window from Telnet's POV.
 683  */
 684 static void ssh_size(void) {
 685     switch (ssh_state) {
 686       case SSH_STATE_BEFORE_SIZE:
 687       case SSH_STATE_CLOSED:
 688         break;                         /* do nothing */
 689       case SSH_STATE_INTERMED:
 690         size_needed = TRUE;            /* buffer for later */
 691         break;
 692       case SSH_STATE_SESSION:
 693         if (!cfg.nopty) {
 694             s_wrpkt_start(11, 16);
 695             pktout.body[0] = (rows >> 24) & 0xFF;
 696             pktout.body[1] = (rows >> 16) & 0xFF;
 697             pktout.body[2] = (rows >> 8) & 0xFF;
 698             pktout.body[3] = rows & 0xFF;
 699             pktout.body[4] = (cols >> 24) & 0xFF;
 700             pktout.body[5] = (cols >> 16) & 0xFF;
 701             pktout.body[6] = (cols >> 8) & 0xFF;
 702             pktout.body[7] = cols & 0xFF;
 703             memset(pktout.body+8, 0, 8);
 704             s_wrpkt();
 705         }
 706     }
 707 }
 708
 709 /*
 710  * (Send Telnet special codes)
 711  */
 712 static void ssh_special (Telnet_Special code) {
 713     /* do nothing */
 714 }
 715
 716 Backend ssh_backend = {
 717     ssh_init,
 718     ssh_msg,
 719     ssh_send,
 720     ssh_size,
 721     ssh_special
 722 };