SSH2 transport layer now enables encryption and MAC successfully for 3DES
[u/mdw/putty] / ssh.c
1 #include <stdio.h>
2 #include <stdlib.h>
3 #include <stdarg.h>
4 #include <assert.h>
5 #include <winsock.h>
6
7 #include "putty.h"
8 #include "ssh.h"
9 #include "scp.h"
10
11 #ifndef FALSE
12 #define FALSE 0
13 #endif
14 #ifndef TRUE
15 #define TRUE 1
16 #endif
17
18 #define logevent(s) { logevent(s); \
19 if (IS_SCP && (scp_flags & SCP_VERBOSE) != 0) \
20 fprintf(stderr, "%s\n", s); }
21
22 #define SSH1_MSG_DISCONNECT 1
23 #define SSH1_SMSG_PUBLIC_KEY 2
24 #define SSH1_CMSG_SESSION_KEY 3
25 #define SSH1_CMSG_USER 4
26 #define SSH1_CMSG_AUTH_PASSWORD 9
27 #define SSH1_CMSG_REQUEST_PTY 10
28 #define SSH1_CMSG_WINDOW_SIZE 11
29 #define SSH1_CMSG_EXEC_SHELL 12
30 #define SSH1_CMSG_EXEC_CMD 13
31 #define SSH1_SMSG_SUCCESS 14
32 #define SSH1_SMSG_FAILURE 15
33 #define SSH1_CMSG_STDIN_DATA 16
34 #define SSH1_SMSG_STDOUT_DATA 17
35 #define SSH1_SMSG_STDERR_DATA 18
36 #define SSH1_CMSG_EOF 19
37 #define SSH1_SMSG_EXIT_STATUS 20
38 #define SSH1_CMSG_EXIT_CONFIRMATION 33
39 #define SSH1_MSG_IGNORE 32
40 #define SSH1_MSG_DEBUG 36
41 #define SSH1_CMSG_AUTH_TIS 39
42 #define SSH1_SMSG_AUTH_TIS_CHALLENGE 40
43 #define SSH1_CMSG_AUTH_TIS_RESPONSE 41
44
45 #define SSH1_AUTH_TIS 5
46
47 #define SSH2_MSG_DISCONNECT 1
48 #define SSH2_MSG_IGNORE 2
49 #define SSH2_MSG_UNIMPLEMENTED 3
50 #define SSH2_MSG_DEBUG 4
51 #define SSH2_MSG_SERVICE_REQUEST 5
52 #define SSH2_MSG_SERVICE_ACCEPT 6
53 #define SSH2_MSG_KEXINIT 20
54 #define SSH2_MSG_NEWKEYS 21
55 #define SSH2_MSG_KEXDH_INIT 30
56 #define SSH2_MSG_KEXDH_REPLY 31
57
58 #define GET_32BIT(cp) \
59 (((unsigned long)(unsigned char)(cp)[0] << 24) | \
60 ((unsigned long)(unsigned char)(cp)[1] << 16) | \
61 ((unsigned long)(unsigned char)(cp)[2] << 8) | \
62 ((unsigned long)(unsigned char)(cp)[3]))
63
64 #define PUT_32BIT(cp, value) { \
65 (cp)[0] = (unsigned char)((value) >> 24); \
66 (cp)[1] = (unsigned char)((value) >> 16); \
67 (cp)[2] = (unsigned char)((value) >> 8); \
68 (cp)[3] = (unsigned char)(value); }
69
70 enum { PKT_END, PKT_INT, PKT_CHAR, PKT_DATA, PKT_STR };
71
72 /* Coroutine mechanics for the sillier bits of the code */
73 #define crBegin1 static int crLine = 0;
74 #define crBegin2 switch(crLine) { case 0:;
75 #define crBegin crBegin1; crBegin2;
76 #define crFinish(z) } crLine = 0; return (z)
77 #define crFinishV } crLine = 0; return
78 #define crReturn(z) \
79 do {\
80 crLine=__LINE__; return (z); case __LINE__:;\
81 } while (0)
82 #define crReturnV \
83 do {\
84 crLine=__LINE__; return; case __LINE__:;\
85 } while (0)
86 #define crStop(z) do{ crLine = 0; return (z); }while(0)
87 #define crStopV do{ crLine = 0; return; }while(0)
88 #define crWaitUntil(c) do { crReturn(0); } while (!(c))
89
90 extern struct ssh_cipher ssh_3des;
91 extern struct ssh_cipher ssh_3des_ssh2;
92 extern struct ssh_cipher ssh_des;
93 extern struct ssh_cipher ssh_blowfish;
94
95 /* for ssh 2; we miss out single-DES because it isn't supported */
96 struct ssh_cipher *ciphers[] = { &ssh_3des_ssh2, &ssh_blowfish };
97
98 extern struct ssh_kex ssh_diffiehellman;
99 struct ssh_kex *kex_algs[] = { &ssh_diffiehellman };
100
101 extern struct ssh_hostkey ssh_dss;
102 struct ssh_hostkey *hostkey_algs[] = { &ssh_dss };
103
104 extern struct ssh_mac ssh_sha1;
105
106 SHA_State exhash;
107
108 static void nullmac_key(unsigned char *key) { }
109 static void nullmac_generate(unsigned char *blk, int len, unsigned long seq) { }
110 static int nullmac_verify(unsigned char *blk, int len, unsigned long seq) { return 1; }
111 struct ssh_mac ssh_mac_none = {
112 nullmac_key, nullmac_key, nullmac_generate, nullmac_verify, "none", 0
113 };
114 struct ssh_mac *macs[] = { &ssh_sha1, &ssh_mac_none };
115
116 struct ssh_compress ssh_comp_none = {
117 "none"
118 };
119 struct ssh_compress *compressions[] = { &ssh_comp_none };
120
121 static SOCKET s = INVALID_SOCKET;
122
123 static unsigned char session_key[32];
124 static struct ssh_cipher *cipher = NULL;
125 static struct ssh_cipher *cscipher = NULL;
126 static struct ssh_cipher *sccipher = NULL;
127 static struct ssh_mac *csmac = NULL;
128 static struct ssh_mac *scmac = NULL;
129 static struct ssh_compress *cscomp = NULL;
130 static struct ssh_compress *sccomp = NULL;
131 static struct ssh_kex *kex = NULL;
132 static struct ssh_hostkey *hostkey = NULL;
133 int scp_flags = 0;
134 int (*ssh_get_password)(const char *prompt, char *str, int maxlen) = NULL;
135
136 static char *savedhost;
137
138 static enum {
139 SSH_STATE_BEFORE_SIZE,
140 SSH_STATE_INTERMED,
141 SSH_STATE_SESSION,
142 SSH_STATE_CLOSED
143 } ssh_state = SSH_STATE_BEFORE_SIZE;
144
145 static int size_needed = FALSE;
146
147 static void s_write (char *buf, int len) {
148 while (len > 0) {
149 int i = send (s, buf, len, 0);
150 if (IS_SCP) {
151 noise_ultralight(i);
152 if (i <= 0)
153 fatalbox("Lost connection while sending");
154 }
155 if (i > 0)
156 len -= i, buf += i;
157 }
158 }
159
160 static int s_read (char *buf, int len) {
161 int ret = 0;
162 while (len > 0) {
163 int i = recv (s, buf, len, 0);
164 if (IS_SCP)
165 noise_ultralight(i);
166 if (i > 0)
167 len -= i, buf += i, ret += i;
168 else
169 return i;
170 }
171 return ret;
172 }
173
174 static void c_write (char *buf, int len) {
175 if (IS_SCP) {
176 if (len > 0 && buf[len-1] == '\n') len--;
177 if (len > 0 && buf[len-1] == '\r') len--;
178 if (len > 0) { fwrite(buf, len, 1, stderr); fputc('\n', stderr); }
179 return;
180 }
181 while (len--)
182 c_write1(*buf++);
183 }
184
185 struct Packet {
186 long length;
187 int type;
188 unsigned char *data;
189 unsigned char *body;
190 long savedpos;
191 long maxlen;
192 };
193
194 static struct Packet pktin = { 0, 0, NULL, NULL, 0 };
195 static struct Packet pktout = { 0, 0, NULL, NULL, 0 };
196
197 static void (*ssh_protocol)(unsigned char *in, int inlen, int ispkt);
198 static void ssh1_protocol(unsigned char *in, int inlen, int ispkt);
199 static void ssh2_protocol(unsigned char *in, int inlen, int ispkt);
200 static void ssh_size(void);
201
202 static int (*s_rdpkt)(unsigned char **data, int *datalen);
203
204 /*
205 * Collect incoming data in the incoming packet buffer.
206 * Decipher and verify the packet when it is completely read.
207 * Drop SSH1_MSG_DEBUG and SSH1_MSG_IGNORE packets.
208 * Update the *data and *datalen variables.
209 * Return the additional nr of bytes needed, or 0 when
210 * a complete packet is available.
211 */
212 static int ssh1_rdpkt(unsigned char **data, int *datalen)
213 {
214 static long len, pad, biglen, to_read;
215 static unsigned long realcrc, gotcrc;
216 static unsigned char *p;
217 static int i;
218
219 crBegin;
220
221 next_packet:
222
223 pktin.type = 0;
224 pktin.length = 0;
225
226 for (i = len = 0; i < 4; i++) {
227 while ((*datalen) == 0)
228 crReturn(4-i);
229 len = (len << 8) + **data;
230 (*data)++, (*datalen)--;
231 }
232
233 #ifdef FWHACK
234 if (len == 0x52656d6f) { /* "Remo"te server has closed ... */
235 len = 0x300; /* big enough to carry to end */
236 }
237 #endif
238
239 pad = 8 - (len % 8);
240 biglen = len + pad;
241 pktin.length = len - 5;
242
243 if (pktin.maxlen < biglen) {
244 pktin.maxlen = biglen;
245 pktin.data = (pktin.data == NULL ? malloc(biglen+APIEXTRA) :
246 realloc(pktin.data, biglen+APIEXTRA));
247 if (!pktin.data)
248 fatalbox("Out of memory");
249 }
250
251 to_read = biglen;
252 p = pktin.data;
253 while (to_read > 0) {
254 static int chunk;
255 chunk = to_read;
256 while ((*datalen) == 0)
257 crReturn(to_read);
258 if (chunk > (*datalen))
259 chunk = (*datalen);
260 memcpy(p, *data, chunk);
261 *data += chunk;
262 *datalen -= chunk;
263 p += chunk;
264 to_read -= chunk;
265 }
266
267 if (cipher)
268 cipher->decrypt(pktin.data, biglen);
269
270 pktin.type = pktin.data[pad];
271 pktin.body = pktin.data + pad + 1;
272
273 realcrc = crc32(pktin.data, biglen-4);
274 gotcrc = GET_32BIT(pktin.data+biglen-4);
275 if (gotcrc != realcrc) {
276 fatalbox("Incorrect CRC received on packet");
277 }
278
279 if (pktin.type == SSH1_SMSG_STDOUT_DATA ||
280 pktin.type == SSH1_SMSG_STDERR_DATA ||
281 pktin.type == SSH1_MSG_DEBUG ||
282 pktin.type == SSH1_SMSG_AUTH_TIS_CHALLENGE) {
283 long strlen = GET_32BIT(pktin.body);
284 if (strlen + 4 != pktin.length)
285 fatalbox("Received data packet with bogus string length");
286 }
287
288 if (pktin.type == SSH1_MSG_DEBUG) {
289 /* log debug message */
290 char buf[80];
291 int strlen = GET_32BIT(pktin.body);
292 strcpy(buf, "Remote: ");
293 if (strlen > 70) strlen = 70;
294 memcpy(buf+8, pktin.body+4, strlen);
295 buf[8+strlen] = '\0';
296 logevent(buf);
297 goto next_packet;
298 } else if (pktin.type == SSH1_MSG_IGNORE) {
299 /* do nothing */
300 goto next_packet;
301 }
302
303 crFinish(0);
304 }
305
306 static int ssh2_rdpkt(unsigned char **data, int *datalen)
307 {
308 static long len, pad, payload, packetlen, maclen;
309 static int i;
310 static int cipherblk;
311 static unsigned long incoming_sequence = 0;
312
313 crBegin;
314
315 next_packet:
316
317 pktin.type = 0;
318 pktin.length = 0;
319
320 if (cipher)
321 cipherblk = cipher->blksize;
322 else
323 cipherblk = 8;
324 if (cipherblk < 8)
325 cipherblk = 8;
326
327 if (pktin.maxlen < cipherblk) {
328 pktin.maxlen = cipherblk;
329 pktin.data = (pktin.data == NULL ? malloc(cipherblk+APIEXTRA) :
330 realloc(pktin.data, cipherblk+APIEXTRA));
331 if (!pktin.data)
332 fatalbox("Out of memory");
333 }
334
335 /*
336 * Acquire and decrypt the first block of the packet. This will
337 * contain the length and padding details.
338 */
339 for (i = len = 0; i < cipherblk; i++) {
340 while ((*datalen) == 0)
341 crReturn(cipherblk-i);
342 pktin.data[i] = *(*data)++;
343 (*datalen)--;
344 }
345 #ifdef FWHACK
346 if (!memcmp(pktin.data, "Remo", 4)) {/* "Remo"te server has closed ... */
347 /* FIXME */
348 }
349 #endif
350 debug(("Got initblk:"));
351 for (i = 0; i < cipherblk; i++)
352 debug((" %02x", (unsigned char)pktin.data[i]));
353 debug(("\r\n"));
354 if (sccipher)
355 sccipher->decrypt(pktin.data, cipherblk);
356 debug(("Decrypted initblk:"));
357 for (i = 0; i < cipherblk; i++)
358 debug((" %02x", (unsigned char)pktin.data[i]));
359 debug(("\r\n"));
360
361 /*
362 * Now get the length and padding figures.
363 */
364 len = GET_32BIT(pktin.data);
365 pad = pktin.data[4];
366
367 /*
368 * This enables us to deduce the payload length.
369 */
370 payload = len - pad - 1;
371
372 pktin.length = payload + 5;
373
374 /*
375 * So now we can work out the total packet length.
376 */
377 packetlen = len + 4;
378 maclen = scmac ? scmac->len : 0;
379
380 /*
381 * Adjust memory allocation if packet is too big.
382 */
383 if (pktin.maxlen < packetlen) {
384 pktin.maxlen = packetlen;
385 pktin.data = (pktin.data == NULL ? malloc(packetlen+APIEXTRA) :
386 realloc(pktin.data, packetlen+APIEXTRA));
387 if (!pktin.data)
388 fatalbox("Out of memory");
389 }
390
391 /*
392 * Read and decrypt the remainder of the packet.
393 */
394 for (i = cipherblk; i < packetlen + maclen; i++) {
395 while ((*datalen) == 0)
396 crReturn(packetlen + maclen - i);
397 pktin.data[i] = *(*data)++;
398 (*datalen)--;
399 }
400 /* Decrypt everything _except_ the MAC. */
401 if (sccipher)
402 sccipher->decrypt(pktin.data + cipherblk, packetlen - cipherblk);
403
404 debug(("Got packet len=%d pad=%d\r\n", len, pad));
405 for (i = 0; i < packetlen; i++)
406 debug((" %02x", (unsigned char)pktin.data[i]));
407 debug(("\r\n"));
408
409 /*
410 * Check the MAC.
411 */
412 if (scmac && !scmac->verify(pktin.data, len+4, incoming_sequence))
413 fatalbox("Incorrect MAC received on packet");
414 incoming_sequence++; /* whether or not we MACed */
415
416 pktin.savedpos = 6;
417 pktin.type = pktin.data[5];
418
419 /*
420 * FIXME: handle IGNORE and DEBUG messages.
421 */
422
423 crFinish(0);
424 }
425
426 static void ssh_gotdata(unsigned char *data, int datalen)
427 {
428 while (datalen > 0) {
429 if ( s_rdpkt(&data, &datalen) == 0 ) {
430 ssh_protocol(NULL, 0, 1);
431 if (ssh_state == SSH_STATE_CLOSED) {
432 return;
433 }
434 }
435 }
436 }
437
438
439 static void s_wrpkt_start(int type, int len) {
440 int pad, biglen;
441
442 len += 5; /* type and CRC */
443 pad = 8 - (len%8);
444 biglen = len + pad;
445
446 pktout.length = len-5;
447 if (pktout.maxlen < biglen) {
448 pktout.maxlen = biglen;
449 #ifdef MSCRYPTOAPI
450 /* Allocate enough buffer space for extra block
451 * for MS CryptEncrypt() */
452 pktout.data = (pktout.data == NULL ? malloc(biglen+12) :
453 realloc(pktout.data, biglen+12));
454 #else
455 pktout.data = (pktout.data == NULL ? malloc(biglen+4) :
456 realloc(pktout.data, biglen+4));
457 #endif
458 if (!pktout.data)
459 fatalbox("Out of memory");
460 }
461
462 pktout.type = type;
463 pktout.body = pktout.data+4+pad+1;
464 }
465
466 static void s_wrpkt(void) {
467 int pad, len, biglen, i;
468 unsigned long crc;
469
470 len = pktout.length + 5; /* type and CRC */
471 pad = 8 - (len%8);
472 biglen = len + pad;
473
474 pktout.body[-1] = pktout.type;
475 for (i=0; i<pad; i++)
476 pktout.data[i+4] = random_byte();
477 crc = crc32(pktout.data+4, biglen-4);
478 PUT_32BIT(pktout.data+biglen, crc);
479 PUT_32BIT(pktout.data, len);
480
481 if (cipher)
482 cipher->encrypt(pktout.data+4, biglen);
483
484 s_write(pktout.data, biglen+4);
485 }
486
487 /*
488 * Construct a packet with the specified contents and
489 * send it to the server.
490 */
491 static void send_packet(int pkttype, ...)
492 {
493 va_list args;
494 unsigned char *p, *argp, argchar;
495 unsigned long argint;
496 int pktlen, argtype, arglen;
497
498 pktlen = 0;
499 va_start(args, pkttype);
500 while ((argtype = va_arg(args, int)) != PKT_END) {
501 switch (argtype) {
502 case PKT_INT:
503 (void) va_arg(args, int);
504 pktlen += 4;
505 break;
506 case PKT_CHAR:
507 (void) va_arg(args, char);
508 pktlen++;
509 break;
510 case PKT_DATA:
511 (void) va_arg(args, unsigned char *);
512 arglen = va_arg(args, int);
513 pktlen += arglen;
514 break;
515 case PKT_STR:
516 argp = va_arg(args, unsigned char *);
517 arglen = strlen(argp);
518 pktlen += 4 + arglen;
519 break;
520 default:
521 assert(0);
522 }
523 }
524 va_end(args);
525
526 s_wrpkt_start(pkttype, pktlen);
527 p = pktout.body;
528
529 va_start(args, pkttype);
530 while ((argtype = va_arg(args, int)) != PKT_END) {
531 switch (argtype) {
532 case PKT_INT:
533 argint = va_arg(args, int);
534 PUT_32BIT(p, argint);
535 p += 4;
536 break;
537 case PKT_CHAR:
538 argchar = va_arg(args, unsigned char);
539 *p = argchar;
540 p++;
541 break;
542 case PKT_DATA:
543 argp = va_arg(args, unsigned char *);
544 arglen = va_arg(args, int);
545 memcpy(p, argp, arglen);
546 p += arglen;
547 break;
548 case PKT_STR:
549 argp = va_arg(args, unsigned char *);
550 arglen = strlen(argp);
551 PUT_32BIT(p, arglen);
552 memcpy(p + 4, argp, arglen);
553 p += 4 + arglen;
554 break;
555 }
556 }
557 va_end(args);
558
559 s_wrpkt();
560 }
561
562
563 /*
564 * Connect to specified host and port.
565 * Returns an error message, or NULL on success.
566 * Also places the canonical host name into `realhost'.
567 */
568 static char *connect_to_host(char *host, int port, char **realhost)
569 {
570 SOCKADDR_IN addr;
571 struct hostent *h;
572 unsigned long a;
573 #ifdef FWHACK
574 char *FWhost;
575 int FWport;
576 #endif
577
578 savedhost = malloc(1+strlen(host));
579 if (!savedhost)
580 fatalbox("Out of memory");
581 strcpy(savedhost, host);
582
583 if (port < 0)
584 port = 22; /* default ssh port */
585
586 #ifdef FWHACK
587 FWhost = host;
588 FWport = port;
589 host = FWSTR;
590 port = 23;
591 #endif
592
593 /*
594 * Try to find host.
595 */
596 if ( (a = inet_addr(host)) == (unsigned long) INADDR_NONE) {
597 if ( (h = gethostbyname(host)) == NULL)
598 switch (WSAGetLastError()) {
599 case WSAENETDOWN: return "Network is down";
600 case WSAHOST_NOT_FOUND: case WSANO_DATA:
601 return "Host does not exist";
602 case WSATRY_AGAIN: return "Host not found";
603 default: return "gethostbyname: unknown error";
604 }
605 memcpy (&a, h->h_addr, sizeof(a));
606 *realhost = h->h_name;
607 } else
608 *realhost = host;
609 #ifdef FWHACK
610 *realhost = FWhost;
611 #endif
612 a = ntohl(a);
613
614 /*
615 * Open socket.
616 */
617 s = socket(AF_INET, SOCK_STREAM, 0);
618 if (s == INVALID_SOCKET)
619 switch (WSAGetLastError()) {
620 case WSAENETDOWN: return "Network is down";
621 case WSAEAFNOSUPPORT: return "TCP/IP support not present";
622 default: return "socket(): unknown error";
623 }
624
625 /*
626 * Bind to local address.
627 */
628 addr.sin_family = AF_INET;
629 addr.sin_addr.s_addr = htonl(INADDR_ANY);
630 addr.sin_port = htons(0);
631 if (bind (s, (struct sockaddr *)&addr, sizeof(addr)) == SOCKET_ERROR)
632 switch (WSAGetLastError()) {
633 case WSAENETDOWN: return "Network is down";
634 default: return "bind(): unknown error";
635 }
636
637 /*
638 * Connect to remote address.
639 */
640 addr.sin_addr.s_addr = htonl(a);
641 addr.sin_port = htons((short)port);
642 if (connect (s, (struct sockaddr *)&addr, sizeof(addr)) == SOCKET_ERROR)
643 switch (WSAGetLastError()) {
644 case WSAENETDOWN: return "Network is down";
645 case WSAECONNREFUSED: return "Connection refused";
646 case WSAENETUNREACH: return "Network is unreachable";
647 case WSAEHOSTUNREACH: return "No route to host";
648 default: return "connect(): unknown error";
649 }
650
651 #ifdef FWHACK
652 send(s, "connect ", 8, 0);
653 send(s, FWhost, strlen(FWhost), 0);
654 {
655 char buf[20];
656 sprintf(buf, " %d\n", FWport);
657 send (s, buf, strlen(buf), 0);
658 }
659 #endif
660
661 return NULL;
662 }
663
664 static int ssh_versioncmp(char *a, char *b) {
665 char *ae, *be;
666 unsigned long av, bv;
667
668 av = strtoul(a, &ae, 10);
669 bv = strtoul(b, &be, 10);
670 if (av != bv) return (av < bv ? -1 : +1);
671 if (*ae == '.') ae++;
672 if (*be == '.') be++;
673 av = strtoul(ae, &ae, 10);
674 bv = strtoul(be, &be, 10);
675 if (av != bv) return (av < bv ? -1 : +1);
676 return 0;
677 }
678
679
680 /*
681 * Utility routine for putting an SSH-protocol `string' into a SHA
682 * state.
683 */
684 #include <stdio.h>
685 void sha_string(SHA_State *s, void *str, int len) {
686 unsigned char lenblk[4];
687 static FILE *fp;
688 PUT_32BIT(lenblk, len);
689 if (!fp) fp = fopen("h:\\statham\\windows\\putty\\data","wb");
690 fwrite(lenblk, 4, 1, fp);
691 SHA_Bytes(s, lenblk, 4);
692 fwrite(str, len, 1, fp);
693 fflush(fp);
694 SHA_Bytes(s, str, len);
695 }
696
697 static int do_ssh_init(void) {
698 char c, *vsp;
699 char version[10];
700 char vstring[80];
701 char vlog[sizeof(vstring)+20];
702 int i;
703
704 #ifdef FWHACK
705 i = 0;
706 while (s_read(&c, 1) == 1) {
707 if (c == 'S' && i < 2) i++;
708 else if (c == 'S' && i == 2) i = 2;
709 else if (c == 'H' && i == 2) break;
710 else i = 0;
711 }
712 #else
713 if (s_read(&c,1) != 1 || c != 'S') return 0;
714 if (s_read(&c,1) != 1 || c != 'S') return 0;
715 if (s_read(&c,1) != 1 || c != 'H') return 0;
716 #endif
717 strcpy(vstring, "SSH-");
718 vsp = vstring+4;
719 if (s_read(&c,1) != 1 || c != '-') return 0;
720 i = 0;
721 while (1) {
722 if (s_read(&c,1) != 1)
723 return 0;
724 if (vsp < vstring+sizeof(vstring)-1)
725 *vsp++ = c;
726 if (i >= 0) {
727 if (c == '-') {
728 version[i] = '\0';
729 i = -1;
730 } else if (i < sizeof(version)-1)
731 version[i++] = c;
732 }
733 else if (c == '\n')
734 break;
735 }
736
737 *vsp = 0;
738 sprintf(vlog, "Server version: %s", vstring);
739 vlog[strcspn(vlog, "\r\n")] = '\0';
740 logevent(vlog);
741
742 if (ssh_versioncmp(version, "1.99") >= 0) {
743 /*
744 * This is a v2 server. Begin v2 protocol.
745 */
746 char *verstring = "SSH-2.0-PuTTY";
747 SHA_Init(&exhash);
748 /*
749 * Hash our version string and their version string.
750 */
751 sha_string(&exhash, verstring, strlen(verstring));
752 sha_string(&exhash, vstring, strcspn(vstring, "\r\n"));
753 sprintf(vstring, "%s\n", verstring);
754 sprintf(vlog, "We claim version: %s", verstring);
755 logevent(vlog);
756 logevent("Using SSH protocol version 2");
757 s_write(vstring, strlen(vstring));
758 ssh_protocol = ssh2_protocol;
759 s_rdpkt = ssh2_rdpkt;
760 } else {
761 /*
762 * This is a v1 server. Begin v1 protocol.
763 */
764 sprintf(vstring, "SSH-%s-PuTTY\n",
765 (ssh_versioncmp(version, "1.5") <= 0 ? version : "1.5"));
766 sprintf(vlog, "We claim version: %s", vstring);
767 vlog[strcspn(vlog, "\r\n")] = '\0';
768 logevent(vlog);
769 logevent("Using SSH protocol version 1");
770 s_write(vstring, strlen(vstring));
771 ssh_protocol = ssh1_protocol;
772 s_rdpkt = ssh1_rdpkt;
773 }
774 return 1;
775 }
776
777 /*
778 * Handle the key exchange and user authentication phases.
779 */
780 static int do_ssh1_login(unsigned char *in, int inlen, int ispkt)
781 {
782 int i, j, len;
783 unsigned char session_id[16];
784 unsigned char *rsabuf, *keystr1, *keystr2;
785 unsigned char cookie[8];
786 struct RSAKey servkey, hostkey;
787 struct MD5Context md5c;
788 static unsigned long supported_ciphers_mask, supported_auths_mask;
789 int cipher_type;
790
791 crBegin;
792
793 if (!ispkt) crWaitUntil(ispkt);
794
795 if (pktin.type != SSH1_SMSG_PUBLIC_KEY)
796 fatalbox("Public key packet not received");
797
798 logevent("Received public keys");
799
800 memcpy(cookie, pktin.body, 8);
801
802 i = makekey(pktin.body+8, &servkey, &keystr1);
803 j = makekey(pktin.body+8+i, &hostkey, &keystr2);
804
805 /*
806 * Hash the host key and print the hash in the log box. Just as
807 * a last resort in case the registry's host key checking is
808 * compromised, we'll allow the user some ability to verify
809 * host keys by eye.
810 */
811 MD5Init(&md5c);
812 MD5Update(&md5c, keystr2, hostkey.bytes);
813 MD5Final(session_id, &md5c);
814 {
815 char logmsg[80];
816 int i;
817 logevent("Host key MD5 is:");
818 strcpy(logmsg, " ");
819 for (i = 0; i < 16; i++)
820 sprintf(logmsg+strlen(logmsg), "%02x", session_id[i]);
821 logevent(logmsg);
822 }
823
824 supported_ciphers_mask = GET_32BIT(pktin.body+12+i+j);
825 supported_auths_mask = GET_32BIT(pktin.body+16+i+j);
826
827 MD5Init(&md5c);
828 MD5Update(&md5c, keystr2, hostkey.bytes);
829 MD5Update(&md5c, keystr1, servkey.bytes);
830 MD5Update(&md5c, pktin.body, 8);
831 MD5Final(session_id, &md5c);
832
833 for (i=0; i<32; i++)
834 session_key[i] = random_byte();
835
836 len = (hostkey.bytes > servkey.bytes ? hostkey.bytes : servkey.bytes);
837
838 rsabuf = malloc(len);
839 if (!rsabuf)
840 fatalbox("Out of memory");
841
842 /*
843 * Verify the host key.
844 */
845 {
846 /*
847 * First format the key into a string.
848 */
849 int len = rsastr_len(&hostkey);
850 char *keystr = malloc(len);
851 if (!keystr)
852 fatalbox("Out of memory");
853 rsastr_fmt(keystr, &hostkey);
854 verify_ssh_host_key(savedhost, keystr);
855 free(keystr);
856 }
857
858 for (i=0; i<32; i++) {
859 rsabuf[i] = session_key[i];
860 if (i < 16)
861 rsabuf[i] ^= session_id[i];
862 }
863
864 if (hostkey.bytes > servkey.bytes) {
865 rsaencrypt(rsabuf, 32, &servkey);
866 rsaencrypt(rsabuf, servkey.bytes, &hostkey);
867 } else {
868 rsaencrypt(rsabuf, 32, &hostkey);
869 rsaencrypt(rsabuf, hostkey.bytes, &servkey);
870 }
871
872 logevent("Encrypted session key");
873
874 cipher_type = cfg.cipher == CIPHER_BLOWFISH ? SSH_CIPHER_BLOWFISH :
875 cfg.cipher == CIPHER_DES ? SSH_CIPHER_DES :
876 SSH_CIPHER_3DES;
877 if ((supported_ciphers_mask & (1 << cipher_type)) == 0) {
878 c_write("Selected cipher not supported, falling back to 3DES\r\n", 53);
879 cipher_type = SSH_CIPHER_3DES;
880 }
881 switch (cipher_type) {
882 case SSH_CIPHER_3DES: logevent("Using 3DES encryption"); break;
883 case SSH_CIPHER_DES: logevent("Using single-DES encryption"); break;
884 case SSH_CIPHER_BLOWFISH: logevent("Using Blowfish encryption"); break;
885 }
886
887 send_packet(SSH1_CMSG_SESSION_KEY,
888 PKT_CHAR, cipher_type,
889 PKT_DATA, cookie, 8,
890 PKT_CHAR, (len*8) >> 8, PKT_CHAR, (len*8) & 0xFF,
891 PKT_DATA, rsabuf, len,
892 PKT_INT, 0,
893 PKT_END);
894
895 logevent("Trying to enable encryption...");
896
897 free(rsabuf);
898
899 cipher = cipher_type == SSH_CIPHER_BLOWFISH ? &ssh_blowfish :
900 cipher_type == SSH_CIPHER_DES ? &ssh_des :
901 &ssh_3des;
902 cipher->sesskey(session_key);
903
904 crWaitUntil(ispkt);
905
906 if (pktin.type != SSH1_SMSG_SUCCESS)
907 fatalbox("Encryption not successfully enabled");
908
909 logevent("Successfully started encryption");
910
911 fflush(stdout);
912 {
913 static char username[100];
914 static int pos = 0;
915 static char c;
916 if (!IS_SCP && !*cfg.username) {
917 c_write("login as: ", 10);
918 while (pos >= 0) {
919 crWaitUntil(!ispkt);
920 while (inlen--) switch (c = *in++) {
921 case 10: case 13:
922 username[pos] = 0;
923 pos = -1;
924 break;
925 case 8: case 127:
926 if (pos > 0) {
927 c_write("\b \b", 3);
928 pos--;
929 }
930 break;
931 case 21: case 27:
932 while (pos > 0) {
933 c_write("\b \b", 3);
934 pos--;
935 }
936 break;
937 case 3: case 4:
938 random_save_seed();
939 exit(0);
940 break;
941 default:
942 if (((c >= ' ' && c <= '~') ||
943 ((unsigned char)c >= 160)) && pos < 40) {
944 username[pos++] = c;
945 c_write(&c, 1);
946 }
947 break;
948 }
949 }
950 c_write("\r\n", 2);
951 username[strcspn(username, "\n\r")] = '\0';
952 } else {
953 char stuff[200];
954 strncpy(username, cfg.username, 99);
955 username[99] = '\0';
956 if (!IS_SCP) {
957 sprintf(stuff, "Sent username \"%s\".\r\n", username);
958 c_write(stuff, strlen(stuff));
959 }
960 }
961
962 send_packet(SSH1_CMSG_USER, PKT_STR, username, PKT_END);
963 {
964 char userlog[20+sizeof(username)];
965 sprintf(userlog, "Sent username \"%s\"", username);
966 logevent(userlog);
967 }
968 }
969
970 crWaitUntil(ispkt);
971
972 while (pktin.type == SSH1_SMSG_FAILURE) {
973 static char password[100];
974 static int pos;
975 static char c;
976 static int pwpkt_type;
977
978 /*
979 * Show password prompt, having first obtained it via a TIS
980 * exchange if we're doing TIS authentication.
981 */
982 pwpkt_type = SSH1_CMSG_AUTH_PASSWORD;
983
984 if (IS_SCP) {
985 char prompt[200];
986 sprintf(prompt, "%s@%s's password: ", cfg.username, savedhost);
987 if (!ssh_get_password(prompt, password, sizeof(password))) {
988 /*
989 * get_password failed to get a password (for
990 * example because one was supplied on the command
991 * line which has already failed to work).
992 * Terminate.
993 */
994 logevent("No more passwords to try");
995 ssh_state = SSH_STATE_CLOSED;
996 crReturn(1);
997 }
998 } else {
999
1000 if (pktin.type == SSH1_SMSG_FAILURE &&
1001 cfg.try_tis_auth &&
1002 (supported_auths_mask & (1<<SSH1_AUTH_TIS))) {
1003 pwpkt_type = SSH1_CMSG_AUTH_TIS_RESPONSE;
1004 logevent("Requested TIS authentication");
1005 send_packet(SSH1_CMSG_AUTH_TIS, PKT_END);
1006 crWaitUntil(ispkt);
1007 if (pktin.type != SSH1_SMSG_AUTH_TIS_CHALLENGE) {
1008 logevent("TIS authentication declined");
1009 c_write("TIS authentication refused.\r\n", 29);
1010 } else {
1011 int challengelen = ((pktin.body[0] << 24) |
1012 (pktin.body[1] << 16) |
1013 (pktin.body[2] << 8) |
1014 (pktin.body[3]));
1015 logevent("Received TIS challenge");
1016 c_write(pktin.body+4, challengelen);
1017 }
1018 }
1019 if (pwpkt_type == SSH1_CMSG_AUTH_PASSWORD)
1020 c_write("password: ", 10);
1021
1022 pos = 0;
1023 while (pos >= 0) {
1024 crWaitUntil(!ispkt);
1025 while (inlen--) switch (c = *in++) {
1026 case 10: case 13:
1027 password[pos] = 0;
1028 pos = -1;
1029 break;
1030 case 8: case 127:
1031 if (pos > 0)
1032 pos--;
1033 break;
1034 case 21: case 27:
1035 pos = 0;
1036 break;
1037 case 3: case 4:
1038 random_save_seed();
1039 exit(0);
1040 break;
1041 default:
1042 if (((c >= ' ' && c <= '~') ||
1043 ((unsigned char)c >= 160)) && pos < 40)
1044 password[pos++] = c;
1045 break;
1046 }
1047 }
1048 c_write("\r\n", 2);
1049
1050 }
1051
1052 send_packet(pwpkt_type, PKT_STR, password, PKT_END);
1053 logevent("Sent password");
1054 memset(password, 0, strlen(password));
1055 crWaitUntil(ispkt);
1056 if (pktin.type == SSH1_SMSG_FAILURE) {
1057 c_write("Access denied\r\n", 15);
1058 logevent("Authentication refused");
1059 } else if (pktin.type == SSH1_MSG_DISCONNECT) {
1060 logevent("Received disconnect request");
1061 ssh_state = SSH_STATE_CLOSED;
1062 crReturn(1);
1063 } else if (pktin.type != SSH1_SMSG_SUCCESS) {
1064 fatalbox("Strange packet received, type %d", pktin.type);
1065 }
1066 }
1067
1068 logevent("Authentication successful");
1069
1070 crFinish(1);
1071 }
1072
1073 static void ssh1_protocol(unsigned char *in, int inlen, int ispkt) {
1074 crBegin;
1075
1076 random_init();
1077
1078 while (!do_ssh1_login(in, inlen, ispkt)) {
1079 crReturnV;
1080 }
1081 if (ssh_state == SSH_STATE_CLOSED)
1082 crReturnV;
1083
1084 if (!cfg.nopty) {
1085 send_packet(SSH1_CMSG_REQUEST_PTY,
1086 PKT_STR, cfg.termtype,
1087 PKT_INT, rows, PKT_INT, cols,
1088 PKT_INT, 0, PKT_INT, 0,
1089 PKT_CHAR, 0,
1090 PKT_END);
1091 ssh_state = SSH_STATE_INTERMED;
1092 do { crReturnV; } while (!ispkt);
1093 if (pktin.type != SSH1_SMSG_SUCCESS && pktin.type != SSH1_SMSG_FAILURE) {
1094 fatalbox("Protocol confusion");
1095 } else if (pktin.type == SSH1_SMSG_FAILURE) {
1096 c_write("Server refused to allocate pty\r\n", 32);
1097 }
1098 logevent("Allocated pty");
1099 }
1100
1101 send_packet(SSH1_CMSG_EXEC_SHELL, PKT_END);
1102 logevent("Started session");
1103
1104 ssh_state = SSH_STATE_SESSION;
1105 if (size_needed)
1106 ssh_size();
1107
1108 while (1) {
1109 crReturnV;
1110 if (ispkt) {
1111 if (pktin.type == SSH1_SMSG_STDOUT_DATA ||
1112 pktin.type == SSH1_SMSG_STDERR_DATA) {
1113 long len = GET_32BIT(pktin.body);
1114 c_write(pktin.body+4, len);
1115 } else if (pktin.type == SSH1_MSG_DISCONNECT) {
1116 ssh_state = SSH_STATE_CLOSED;
1117 logevent("Received disconnect request");
1118 } else if (pktin.type == SSH1_SMSG_SUCCESS) {
1119 /* may be from EXEC_SHELL on some servers */
1120 } else if (pktin.type == SSH1_SMSG_FAILURE) {
1121 /* may be from EXEC_SHELL on some servers
1122 * if no pty is available or in other odd cases. Ignore */
1123 } else if (pktin.type == SSH1_SMSG_EXIT_STATUS) {
1124 send_packet(SSH1_CMSG_EXIT_CONFIRMATION, PKT_END);
1125 } else {
1126 fatalbox("Strange packet received: type %d", pktin.type);
1127 }
1128 } else {
1129 send_packet(SSH1_CMSG_STDIN_DATA,
1130 PKT_INT, inlen, PKT_DATA, in, inlen, PKT_END);
1131 }
1132 }
1133
1134 crFinishV;
1135 }
1136
1137 /*
1138 * SSH2 packet construction functions.
1139 */
1140 void ssh2_pkt_adddata(void *data, int len) {
1141 pktout.length += len;
1142 if (pktout.maxlen < pktout.length) {
1143 pktout.maxlen = pktout.length + 256;
1144 pktout.data = (pktout.data == NULL ? malloc(pktout.maxlen+APIEXTRA) :
1145 realloc(pktout.data, pktout.maxlen+APIEXTRA));
1146 if (!pktout.data)
1147 fatalbox("Out of memory");
1148 }
1149 memcpy(pktout.data+pktout.length-len, data, len);
1150 }
1151 void ssh2_pkt_addbyte(unsigned char byte) {
1152 ssh2_pkt_adddata(&byte, 1);
1153 }
1154 void ssh2_pkt_init(int pkt_type) {
1155 pktout.length = 5;
1156 ssh2_pkt_addbyte((unsigned char)pkt_type);
1157 }
1158 void ssh2_pkt_addbool(unsigned char value) {
1159 ssh2_pkt_adddata(&value, 1);
1160 }
1161 void ssh2_pkt_adduint32(unsigned long value) {
1162 unsigned char x[4];
1163 PUT_32BIT(x, value);
1164 ssh2_pkt_adddata(x, 4);
1165 }
1166 void ssh2_pkt_addstring_start(void) {
1167 ssh2_pkt_adduint32(0);
1168 pktout.savedpos = pktout.length;
1169 }
1170 void ssh2_pkt_addstring_str(char *data) {
1171 ssh2_pkt_adddata(data, strlen(data));
1172 PUT_32BIT(pktout.data + pktout.savedpos - 4,
1173 pktout.length - pktout.savedpos);
1174 }
1175 void ssh2_pkt_addstring_data(char *data, int len) {
1176 ssh2_pkt_adddata(data, len);
1177 PUT_32BIT(pktout.data + pktout.savedpos - 4,
1178 pktout.length - pktout.savedpos);
1179 }
1180 void ssh2_pkt_addstring(char *data) {
1181 ssh2_pkt_addstring_start();
1182 ssh2_pkt_addstring_str(data);
1183 }
1184 char *ssh2_mpint_fmt(Bignum b, int *len) {
1185 unsigned char *p;
1186 int i, n = b[0];
1187 p = malloc(n * 2 + 1);
1188 if (!p)
1189 fatalbox("out of memory");
1190 p[0] = 0;
1191 for (i = 0; i < n; i++) {
1192 p[i*2+1] = (b[n-i] >> 8) & 0xFF;
1193 p[i*2+2] = (b[n-i] ) & 0xFF;
1194 }
1195 i = 0;
1196 while (p[i] == 0 && (p[i+1] & 0x80) == 0)
1197 i++;
1198 memmove(p, p+i, n*2+1-i);
1199 *len = n*2+1-i;
1200 return p;
1201 }
1202 void ssh2_pkt_addmp(Bignum b) {
1203 unsigned char *p;
1204 int len;
1205 p = ssh2_mpint_fmt(b, &len);
1206 ssh2_pkt_addstring_start();
1207 ssh2_pkt_addstring_data(p, len);
1208 free(p);
1209 }
1210 void ssh2_pkt_send(void) {
1211 int cipherblk, maclen, padding, i;
1212 static unsigned long outgoing_sequence = 0;
1213
1214 /*
1215 * Add padding. At least four bytes, and must also bring total
1216 * length (minus MAC) up to a multiple of the block size.
1217 */
1218 cipherblk = cipher ? cipher->blksize : 8; /* block size */
1219 cipherblk = cipherblk < 8 ? 8 : cipherblk; /* or 8 if blksize < 8 */
1220 padding = 4;
1221 padding += (cipherblk - (pktout.length + padding) % cipherblk) % cipherblk;
1222 pktout.data[4] = padding;
1223 for (i = 0; i < padding; i++)
1224 pktout.data[pktout.length + i] = random_byte();
1225 PUT_32BIT(pktout.data, pktout.length + padding - 4);
1226 if (csmac)
1227 csmac->generate(pktout.data, pktout.length + padding,
1228 outgoing_sequence);
1229 outgoing_sequence++; /* whether or not we MACed */
1230 if (cscipher)
1231 cscipher->encrypt(pktout.data, pktout.length + padding);
1232 maclen = csmac ? csmac->len : 0;
1233 #if 0
1234 debug(("Sending packet len=%d\r\n", pktout.length+padding+maclen));
1235 for (i = 0; i < pktout.length+padding+maclen; i++)
1236 debug((" %02x", (unsigned char)pktout.data[i]));
1237 debug(("\r\n"));
1238 #endif
1239 s_write(pktout.data, pktout.length + padding + maclen);
1240 }
1241
1242 void sha_mpint(SHA_State *s, Bignum b) {
1243 unsigned char *p;
1244 int len;
1245 p = ssh2_mpint_fmt(b, &len);
1246 sha_string(s, p, len);
1247 free(p);
1248 }
1249
1250 /*
1251 * SSH2 packet decode functions.
1252 */
1253 void ssh2_pkt_getstring(char **p, int *length) {
1254 *p = NULL;
1255 if (pktin.length - pktin.savedpos < 4)
1256 return;
1257 *length = GET_32BIT(pktin.data+pktin.savedpos);
1258 pktin.savedpos += 4;
1259 if (pktin.length - pktin.savedpos < *length)
1260 return;
1261 *p = pktin.data+pktin.savedpos;
1262 pktin.savedpos += *length;
1263 }
1264 Bignum ssh2_pkt_getmp(void) {
1265 char *p;
1266 int i, j, length;
1267 Bignum b;
1268
1269 ssh2_pkt_getstring(&p, &length);
1270 if (!p)
1271 return NULL;
1272 if (p[0] & 0x80)
1273 fatalbox("internal error: Can't handle negative mpints");
1274 b = newbn((length+1)/2);
1275 for (i = 0; i < length; i++) {
1276 j = length - 1 - i;
1277 if (j & 1)
1278 b[j/2+1] |= ((unsigned char)p[i]) << 8;
1279 else
1280 b[j/2+1] |= ((unsigned char)p[i]);
1281 }
1282 return b;
1283 }
1284
1285 void bndebug(char *string, Bignum b) {
1286 unsigned char *p;
1287 int i, len;
1288 p = ssh2_mpint_fmt(b, &len);
1289 debug(("%s", string));
1290 for (i = 0; i < len; i++)
1291 debug((" %02x", p[i]));
1292 debug(("\r\n"));
1293 free(p);
1294 }
1295
1296 /*
1297 * Utility routine for decoding comma-separated strings in KEXINIT.
1298 */
1299 int in_commasep_string(char *needle, char *haystack, int haylen) {
1300 int needlen = strlen(needle);
1301 while (1) {
1302 /*
1303 * Is it at the start of the string?
1304 */
1305 if (haylen >= needlen && /* haystack is long enough */
1306 !memcmp(needle, haystack, needlen) && /* initial match */
1307 (haylen == needlen || haystack[needlen] == ',')
1308 /* either , or EOS follows */
1309 )
1310 return 1;
1311 /*
1312 * If not, search for the next comma and resume after that.
1313 * If no comma found, terminate.
1314 */
1315 while (haylen > 0 && *haystack != ',')
1316 haylen--, haystack++;
1317 if (haylen == 0)
1318 return 0;
1319 haylen--, haystack++; /* skip over comma itself */
1320 }
1321 }
1322
1323 /*
1324 * SSH2 key creation method.
1325 */
1326 void ssh2_mkkey(Bignum K, char *H, char chr, char *keyspace) {
1327 SHA_State s;
1328 /* First 20 bytes. */
1329 SHA_Init(&s);
1330 sha_mpint(&s, K);
1331 SHA_Bytes(&s, H, 20);
1332 SHA_Bytes(&s, &chr, 1);
1333 SHA_Bytes(&s, H, 20);
1334 SHA_Final(&s, keyspace);
1335 /* Next 20 bytes. */
1336 SHA_Init(&s);
1337 sha_mpint(&s, K);
1338 SHA_Bytes(&s, H, 20);
1339 SHA_Bytes(&s, keyspace, 20);
1340 SHA_Final(&s, keyspace+20);
1341 }
1342
1343 /*
1344 * Handle the SSH2 key exchange phase.
1345 */
1346 static int do_ssh2_kex(unsigned char *in, int inlen, int ispkt)
1347 {
1348 static int i, len;
1349 static char *str;
1350 static Bignum e, f, K;
1351 static struct ssh_cipher *cscipher_tobe = NULL;
1352 static struct ssh_cipher *sccipher_tobe = NULL;
1353 static struct ssh_mac *csmac_tobe = NULL;
1354 static struct ssh_mac *scmac_tobe = NULL;
1355 static struct ssh_compress *cscomp_tobe = NULL;
1356 static struct ssh_compress *sccomp_tobe = NULL;
1357 static char *hostkeydata, *sigdata;
1358 static int hostkeylen, siglen;
1359 static unsigned char exchange_hash[20];
1360 static unsigned char keyspace[40];
1361
1362 crBegin;
1363
1364 /*
1365 * Construct and send our key exchange packet.
1366 */
1367 ssh2_pkt_init(SSH2_MSG_KEXINIT);
1368 for (i = 0; i < 16; i++)
1369 ssh2_pkt_addbyte((unsigned char)random_byte());
1370 /* List key exchange algorithms. */
1371 ssh2_pkt_addstring_start();
1372 for (i = 0; i < lenof(kex_algs); i++) {
1373 ssh2_pkt_addstring_str(kex_algs[i]->name);
1374 if (i < lenof(kex_algs)-1)
1375 ssh2_pkt_addstring_str(",");
1376 }
1377 /* List server host key algorithms. */
1378 ssh2_pkt_addstring_start();
1379 for (i = 0; i < lenof(hostkey_algs); i++) {
1380 ssh2_pkt_addstring_str(hostkey_algs[i]->name);
1381 if (i < lenof(hostkey_algs)-1)
1382 ssh2_pkt_addstring_str(",");
1383 }
1384 /* List client->server encryption algorithms. */
1385 ssh2_pkt_addstring_start();
1386 for (i = 0; i < lenof(ciphers); i++) {
1387 ssh2_pkt_addstring_str(ciphers[i]->name);
1388 if (i < lenof(ciphers)-1)
1389 ssh2_pkt_addstring_str(",");
1390 }
1391 /* List server->client encryption algorithms. */
1392 ssh2_pkt_addstring_start();
1393 for (i = 0; i < lenof(ciphers); i++) {
1394 ssh2_pkt_addstring_str(ciphers[i]->name);
1395 if (i < lenof(ciphers)-1)
1396 ssh2_pkt_addstring_str(",");
1397 }
1398 /* List client->server MAC algorithms. */
1399 ssh2_pkt_addstring_start();
1400 for (i = 0; i < lenof(macs); i++) {
1401 ssh2_pkt_addstring_str(macs[i]->name);
1402 if (i < lenof(macs)-1)
1403 ssh2_pkt_addstring_str(",");
1404 }
1405 /* List server->client MAC algorithms. */
1406 ssh2_pkt_addstring_start();
1407 for (i = 0; i < lenof(macs); i++) {
1408 ssh2_pkt_addstring_str(macs[i]->name);
1409 if (i < lenof(macs)-1)
1410 ssh2_pkt_addstring_str(",");
1411 }
1412 /* List client->server compression algorithms. */
1413 ssh2_pkt_addstring_start();
1414 for (i = 0; i < lenof(compressions); i++) {
1415 ssh2_pkt_addstring_str(compressions[i]->name);
1416 if (i < lenof(compressions)-1)
1417 ssh2_pkt_addstring_str(",");
1418 }
1419 /* List server->client compression algorithms. */
1420 ssh2_pkt_addstring_start();
1421 for (i = 0; i < lenof(compressions); i++) {
1422 ssh2_pkt_addstring_str(compressions[i]->name);
1423 if (i < lenof(compressions)-1)
1424 ssh2_pkt_addstring_str(",");
1425 }
1426 /* List client->server languages. Empty list. */
1427 ssh2_pkt_addstring_start();
1428 /* List server->client languages. Empty list. */
1429 ssh2_pkt_addstring_start();
1430 /* First KEX packet does _not_ follow, because we're not that brave. */
1431 ssh2_pkt_addbool(FALSE);
1432 /* Reserved. */
1433 ssh2_pkt_adduint32(0);
1434 sha_string(&exhash, pktout.data+5, pktout.length-5);
1435 ssh2_pkt_send();
1436
1437 if (!ispkt) crWaitUntil(ispkt);
1438 sha_string(&exhash, pktin.data+5, pktin.length-5);
1439
1440 /*
1441 * Now examine the other side's KEXINIT to see what we're up
1442 * to.
1443 */
1444 if (pktin.type != SSH2_MSG_KEXINIT)
1445 fatalbox("expected key exchange packet from server");
1446 kex = NULL; hostkey = NULL; cscipher_tobe = NULL; sccipher_tobe = NULL;
1447 csmac_tobe = NULL; scmac_tobe = NULL; cscomp_tobe = NULL; sccomp_tobe = NULL;
1448 pktin.savedpos += 16; /* skip garbage cookie */
1449 ssh2_pkt_getstring(&str, &len); /* key exchange algorithms */
1450 for (i = 0; i < lenof(kex_algs); i++) {
1451 if (in_commasep_string(kex_algs[i]->name, str, len)) {
1452 kex = kex_algs[i];
1453 break;
1454 }
1455 }
1456 ssh2_pkt_getstring(&str, &len); /* host key algorithms */
1457 for (i = 0; i < lenof(hostkey_algs); i++) {
1458 if (in_commasep_string(hostkey_algs[i]->name, str, len)) {
1459 hostkey = hostkey_algs[i];
1460 break;
1461 }
1462 }
1463 ssh2_pkt_getstring(&str, &len); /* client->server cipher */
1464 for (i = 0; i < lenof(ciphers); i++) {
1465 if (in_commasep_string(ciphers[i]->name, str, len)) {
1466 cscipher_tobe = ciphers[i];
1467 break;
1468 }
1469 }
1470 ssh2_pkt_getstring(&str, &len); /* server->client cipher */
1471 for (i = 0; i < lenof(ciphers); i++) {
1472 if (in_commasep_string(ciphers[i]->name, str, len)) {
1473 sccipher_tobe = ciphers[i];
1474 break;
1475 }
1476 }
1477 ssh2_pkt_getstring(&str, &len); /* client->server mac */
1478 for (i = 0; i < lenof(macs); i++) {
1479 if (in_commasep_string(macs[i]->name, str, len)) {
1480 csmac_tobe = macs[i];
1481 break;
1482 }
1483 }
1484 ssh2_pkt_getstring(&str, &len); /* server->client mac */
1485 for (i = 0; i < lenof(macs); i++) {
1486 if (in_commasep_string(macs[i]->name, str, len)) {
1487 scmac_tobe = macs[i];
1488 break;
1489 }
1490 }
1491 ssh2_pkt_getstring(&str, &len); /* client->server compression */
1492 for (i = 0; i < lenof(compressions); i++) {
1493 if (in_commasep_string(compressions[i]->name, str, len)) {
1494 cscomp_tobe = compressions[i];
1495 break;
1496 }
1497 }
1498 ssh2_pkt_getstring(&str, &len); /* server->client compression */
1499 for (i = 0; i < lenof(compressions); i++) {
1500 if (in_commasep_string(compressions[i]->name, str, len)) {
1501 sccomp_tobe = compressions[i];
1502 break;
1503 }
1504 }
1505 debug(("key exchange is %s\r\n", kex ? kex->name : NULL));
1506 debug(("host key alg is %s\r\n", hostkey ? hostkey->name : NULL));
1507 debug(("cscipher alg is %s\r\n", cscipher_tobe ? cscipher_tobe->name : NULL));
1508 debug(("sccipher alg is %s\r\n", sccipher_tobe ? sccipher_tobe->name : NULL));
1509 debug(("csmac alg is %s\r\n", csmac_tobe ? csmac_tobe->name : NULL));
1510 debug(("scmac alg is %s\r\n", scmac_tobe ? scmac_tobe->name : NULL));
1511 debug(("cscomp alg is %s\r\n", cscomp_tobe ? cscomp_tobe->name : NULL));
1512 debug(("sccomp alg is %s\r\n", sccomp_tobe ? sccomp_tobe->name : NULL));
1513
1514 /*
1515 * Currently we only support Diffie-Hellman and DSS, so let's
1516 * bomb out if those aren't selected.
1517 */
1518 if (kex != &ssh_diffiehellman || hostkey != &ssh_dss)
1519 fatalbox("internal fault: chaos in SSH 2 transport layer");
1520
1521 /*
1522 * Now we begin the fun. Generate and send e for Diffie-Hellman.
1523 */
1524 e = dh_create_e();
1525 bndebug("e=", e);
1526 ssh2_pkt_init(SSH2_MSG_KEXDH_INIT);
1527 ssh2_pkt_addmp(e);
1528 ssh2_pkt_send();
1529
1530 crWaitUntil(ispkt);
1531 if (pktin.type != SSH2_MSG_KEXDH_REPLY)
1532 fatalbox("expected key exchange packet from server");
1533 ssh2_pkt_getstring(&hostkeydata, &hostkeylen);
1534 f = ssh2_pkt_getmp();
1535 bndebug("f=", f);
1536 ssh2_pkt_getstring(&sigdata, &siglen);
1537
1538 K = dh_find_K(f);
1539 bndebug("K=", K);
1540
1541 sha_string(&exhash, hostkeydata, hostkeylen);
1542 sha_mpint(&exhash, e);
1543 sha_mpint(&exhash, f);
1544 sha_mpint(&exhash, K);
1545 SHA_Final(&exhash, exchange_hash);
1546
1547 debug(("Exchange hash is:\r\n"));
1548 for (i = 0; i < 20; i++)
1549 debug((" %02x", exchange_hash[i]));
1550 debug(("\r\n"));
1551
1552 /*
1553 * FIXME: verify host key. This bit will be moderately
1554 * unpleasant, because of having to rewrite it to work
1555 * alongside the old scheme.
1556 */
1557
1558 /*
1559 * FIXME: verify signature of exchange hash.
1560 */
1561
1562 /*
1563 * Send SSH2_MSG_NEWKEYS. Expect it from server.
1564 */
1565 ssh2_pkt_init(SSH2_MSG_NEWKEYS);
1566 ssh2_pkt_send();
1567 crWaitUntil(ispkt);
1568 if (pktin.type != SSH2_MSG_NEWKEYS)
1569 fatalbox("expected new-keys packet from server");
1570
1571 /*
1572 * Create and initialise session keys.
1573 */
1574 cscipher = cscipher_tobe;
1575 sccipher = sccipher_tobe;
1576 csmac = csmac_tobe;
1577 scmac = scmac_tobe;
1578 cscomp = cscomp_tobe;
1579 sccomp = sccomp_tobe;
1580 /*
1581 * Set IVs after keys.
1582 */
1583 ssh2_mkkey(K, exchange_hash, 'C', keyspace); cscipher->setcskey(keyspace);
1584 ssh2_mkkey(K, exchange_hash, 'D', keyspace); cscipher->setsckey(keyspace);
1585 ssh2_mkkey(K, exchange_hash, 'A', keyspace); cscipher->setcsiv(keyspace);
1586 ssh2_mkkey(K, exchange_hash, 'B', keyspace); sccipher->setsciv(keyspace);
1587 ssh2_mkkey(K, exchange_hash, 'E', keyspace); csmac->setcskey(keyspace);
1588 ssh2_mkkey(K, exchange_hash, 'F', keyspace); scmac->setsckey(keyspace);
1589
1590 /*
1591 * Now we're encrypting. Send a test packet (FIXME).
1592 */
1593 crWaitUntil(!ispkt);
1594 ssh2_pkt_init(SSH2_MSG_IGNORE);
1595 ssh2_pkt_addstring("oo-er");
1596 ssh2_pkt_send();
1597
1598 crWaitUntil(0);
1599
1600 crFinish(1);
1601 }
1602
1603 static void ssh2_protocol(unsigned char *in, int inlen, int ispkt) {
1604 crBegin;
1605
1606 random_init();
1607
1608 while (!do_ssh2_kex(in, inlen, ispkt)) {
1609 crReturnV;
1610 }
1611
1612 crFinishV;
1613 }
1614
1615 /*
1616 * Called to set up the connection. Will arrange for WM_NETEVENT
1617 * messages to be passed to the specified window, whose window
1618 * procedure should then call telnet_msg().
1619 *
1620 * Returns an error message, or NULL on success.
1621 */
1622 static char *ssh_init (HWND hwnd, char *host, int port, char **realhost) {
1623 char *p;
1624
1625 #ifdef MSCRYPTOAPI
1626 if(crypto_startup() == 0)
1627 return "Microsoft high encryption pack not installed!";
1628 #endif
1629
1630 p = connect_to_host(host, port, realhost);
1631 if (p != NULL)
1632 return p;
1633
1634 if (!do_ssh_init())
1635 return "Protocol initialisation error";
1636
1637 if (WSAAsyncSelect (s, hwnd, WM_NETEVENT, FD_READ | FD_CLOSE) == SOCKET_ERROR)
1638 switch (WSAGetLastError()) {
1639 case WSAENETDOWN: return "Network is down";
1640 default: return "WSAAsyncSelect(): unknown error";
1641 }
1642
1643 return NULL;
1644 }
1645
1646 /*
1647 * Process a WM_NETEVENT message. Will return 0 if the connection
1648 * has closed, or <0 for a socket error.
1649 */
1650 static int ssh_msg (WPARAM wParam, LPARAM lParam) {
1651 int ret;
1652 char buf[256];
1653
1654 /*
1655 * Because reading less than the whole of the available pending
1656 * data can generate an FD_READ event, we need to allow for the
1657 * possibility that FD_READ may arrive with FD_CLOSE already in
1658 * the queue; so it's possible that we can get here even with s
1659 * invalid. If so, we return 1 and don't worry about it.
1660 */
1661 if (s == INVALID_SOCKET)
1662 return 1;
1663
1664 if (WSAGETSELECTERROR(lParam) != 0)
1665 return -WSAGETSELECTERROR(lParam);
1666
1667 switch (WSAGETSELECTEVENT(lParam)) {
1668 case FD_READ:
1669 case FD_CLOSE:
1670 ret = recv(s, buf, sizeof(buf), 0);
1671 if (ret < 0 && WSAGetLastError() == WSAEWOULDBLOCK)
1672 return 1;
1673 if (ret < 0) /* any _other_ error */
1674 return -10000-WSAGetLastError();
1675 if (ret == 0) {
1676 s = INVALID_SOCKET;
1677 return 0;
1678 }
1679 ssh_gotdata (buf, ret);
1680 if (ssh_state == SSH_STATE_CLOSED) {
1681 closesocket(s);
1682 s = INVALID_SOCKET;
1683 return 0;
1684 }
1685 return 1;
1686 }
1687 return 1; /* shouldn't happen, but WTF */
1688 }
1689
1690 /*
1691 * Called to send data down the Telnet connection.
1692 */
1693 static void ssh_send (char *buf, int len) {
1694 if (s == INVALID_SOCKET)
1695 return;
1696
1697 ssh_protocol(buf, len, 0);
1698 }
1699
1700 /*
1701 * Called to set the size of the window from Telnet's POV.
1702 */
1703 static void ssh_size(void) {
1704 switch (ssh_state) {
1705 case SSH_STATE_BEFORE_SIZE:
1706 case SSH_STATE_CLOSED:
1707 break; /* do nothing */
1708 case SSH_STATE_INTERMED:
1709 size_needed = TRUE; /* buffer for later */
1710 break;
1711 case SSH_STATE_SESSION:
1712 if (!cfg.nopty) {
1713 send_packet(SSH1_CMSG_WINDOW_SIZE,
1714 PKT_INT, rows, PKT_INT, cols,
1715 PKT_INT, 0, PKT_INT, 0, PKT_END);
1716 }
1717 }
1718 }
1719
1720 /*
1721 * (Send Telnet special codes)
1722 */
1723 static void ssh_special (Telnet_Special code) {
1724 /* do nothing */
1725 }
1726
1727
1728 /*
1729 * Read and decrypt one incoming SSH packet.
1730 * (only used by pSCP)
1731 */
1732 static void get_packet(void)
1733 {
1734 unsigned char buf[4096], *p;
1735 long to_read;
1736 int len;
1737
1738 assert(IS_SCP);
1739
1740 p = NULL;
1741 len = 0;
1742
1743 while ((to_read = s_rdpkt(&p, &len)) > 0) {
1744 if (to_read > sizeof(buf)) to_read = sizeof(buf);
1745 len = s_read(buf, to_read);
1746 if (len != to_read) {
1747 closesocket(s);
1748 s = INVALID_SOCKET;
1749 return;
1750 }
1751 p = buf;
1752 }
1753
1754 assert(len == 0);
1755 }
1756
1757 /*
1758 * Receive a block of data over the SSH link. Block until
1759 * all data is available. Return nr of bytes read (0 if lost connection).
1760 * (only used by pSCP)
1761 */
1762 int ssh_scp_recv(unsigned char *buf, int len)
1763 {
1764 static int pending_input_len = 0;
1765 static unsigned char *pending_input_ptr;
1766 int to_read = len;
1767
1768 assert(IS_SCP);
1769
1770 if (pending_input_len >= to_read) {
1771 memcpy(buf, pending_input_ptr, to_read);
1772 pending_input_ptr += to_read;
1773 pending_input_len -= to_read;
1774 return len;
1775 }
1776
1777 if (pending_input_len > 0) {
1778 memcpy(buf, pending_input_ptr, pending_input_len);
1779 buf += pending_input_len;
1780 to_read -= pending_input_len;
1781 pending_input_len = 0;
1782 }
1783
1784 if (s == INVALID_SOCKET)
1785 return 0;
1786 while (to_read > 0) {
1787 get_packet();
1788 if (s == INVALID_SOCKET)
1789 return 0;
1790 if (pktin.type == SSH1_SMSG_STDOUT_DATA) {
1791 int plen = GET_32BIT(pktin.body);
1792 if (plen <= to_read) {
1793 memcpy(buf, pktin.body + 4, plen);
1794 buf += plen;
1795 to_read -= plen;
1796 } else {
1797 memcpy(buf, pktin.body + 4, to_read);
1798 pending_input_len = plen - to_read;
1799 pending_input_ptr = pktin.body + 4 + to_read;
1800 to_read = 0;
1801 }
1802 } else if (pktin.type == SSH1_SMSG_STDERR_DATA) {
1803 int plen = GET_32BIT(pktin.body);
1804 fwrite(pktin.body + 4, plen, 1, stderr);
1805 } else if (pktin.type == SSH1_MSG_DISCONNECT) {
1806 logevent("Received disconnect request");
1807 } else if (pktin.type == SSH1_SMSG_SUCCESS ||
1808 pktin.type == SSH1_SMSG_FAILURE) {
1809 /* ignore */
1810 } else if (pktin.type == SSH1_SMSG_EXIT_STATUS) {
1811 char logbuf[100];
1812 sprintf(logbuf, "Remote exit status: %d", GET_32BIT(pktin.body));
1813 logevent(logbuf);
1814 send_packet(SSH1_CMSG_EXIT_CONFIRMATION, PKT_END);
1815 logevent("Closing connection");
1816 closesocket(s);
1817 s = INVALID_SOCKET;
1818 } else {
1819 fatalbox("Strange packet received: type %d", pktin.type);
1820 }
1821 }
1822
1823 return len;
1824 }
1825
1826 /*
1827 * Send a block of data over the SSH link.
1828 * Block until all data is sent.
1829 * (only used by pSCP)
1830 */
1831 void ssh_scp_send(unsigned char *buf, int len)
1832 {
1833 assert(IS_SCP);
1834 if (s == INVALID_SOCKET)
1835 return;
1836 send_packet(SSH1_CMSG_STDIN_DATA,
1837 PKT_INT, len, PKT_DATA, buf, len, PKT_END);
1838 }
1839
1840 /*
1841 * Send an EOF notification to the server.
1842 * (only used by pSCP)
1843 */
1844 void ssh_scp_send_eof(void)
1845 {
1846 assert(IS_SCP);
1847 if (s == INVALID_SOCKET)
1848 return;
1849 send_packet(SSH1_CMSG_EOF, PKT_END);
1850 }
1851
1852 /*
1853 * Set up the connection, login on the remote host and
1854 * start execution of a command.
1855 * Returns an error message, or NULL on success.
1856 * (only used by pSCP)
1857 */
1858 char *ssh_scp_init(char *host, int port, char *cmd, char **realhost)
1859 {
1860 char buf[160], *p;
1861
1862 assert(IS_SCP);
1863
1864 #ifdef MSCRYPTOAPI
1865 if (crypto_startup() == 0)
1866 return "Microsoft high encryption pack not installed!";
1867 #endif
1868
1869 p = connect_to_host(host, port, realhost);
1870 if (p != NULL)
1871 return p;
1872
1873 random_init();
1874
1875 if (!do_ssh_init())
1876 return "Protocol initialisation error";
1877
1878 /* Exchange keys and login */
1879 do {
1880 get_packet();
1881 if (s == INVALID_SOCKET)
1882 return "Connection closed by remote host";
1883 } while (!do_ssh1_login(NULL, 0, 1));
1884
1885 if (ssh_state == SSH_STATE_CLOSED) {
1886 closesocket(s);
1887 s = INVALID_SOCKET;
1888 return "Session initialisation error";
1889 }
1890
1891 /* Execute command */
1892 sprintf(buf, "Sending command: %.100s", cmd);
1893 logevent(buf);
1894 send_packet(SSH1_CMSG_EXEC_CMD, PKT_STR, cmd, PKT_END);
1895
1896 return NULL;
1897 }
1898
1899
1900 Backend ssh_backend = {
1901 ssh_init,
1902 ssh_msg,
1903 ssh_send,
1904 ssh_size,
1905 ssh_special
1906 };
1907