2 * scpssh.c - SSH implementation for PuTTY Secure Copy
3 * Joris van Rantwijk, Aug 1999.
4 * Based on PuTTY ssh.c by Simon Tatham.
16 #define SSH_MSG_DISCONNECT 1
17 #define SSH_SMSG_PUBLIC_KEY 2
18 #define SSH_CMSG_SESSION_KEY 3
19 #define SSH_CMSG_USER 4
20 #define SSH_CMSG_AUTH_PASSWORD 9
21 #define SSH_CMSG_EXEC_CMD 13
22 #define SSH_SMSG_SUCCESS 14
23 #define SSH_SMSG_FAILURE 15
24 #define SSH_CMSG_STDIN_DATA 16
25 #define SSH_SMSG_STDOUT_DATA 17
26 #define SSH_SMSG_STDERR_DATA 18
27 #define SSH_CMSG_EOF 19
28 #define SSH_SMSG_EXIT_STATUS 20
29 #define SSH_CMSG_EXIT_CONFIRMATION 33
30 #define SSH_MSG_IGNORE 32
31 #define SSH_MSG_DEBUG 36
33 #define GET_32BIT(cp) \
34 (((unsigned long)(unsigned char)(cp)[0] << 24) | \
35 ((unsigned long)(unsigned char)(cp)[1] << 16) | \
36 ((unsigned long)(unsigned char)(cp)[2] << 8) | \
37 ((unsigned long)(unsigned char)(cp)[3]))
39 #define PUT_32BIT(cp, value) { \
40 (cp)[0] = (unsigned char)((value) >> 24); \
41 (cp)[1] = (unsigned char)((value) >> 16); \
42 (cp)[2] = (unsigned char)((value) >> 8); \
43 (cp)[3] = (unsigned char)(value); }
45 static SOCKET s = INVALID_SOCKET;
47 static unsigned char session_key[32];
48 static struct ssh_cipher *cipher = NULL;
50 static char *savedhost;
61 static struct Packet pktin = { 0, 0, 0, NULL, 0 };
62 static struct Packet pktout = { 0, 0, 0, NULL, 0 };
65 static void s_write (char *buf, int len) {
67 int i = send (s, buf, len, 0);
70 fatalbox("Lost connection while sending");
75 static int s_read (char *buf, int len) {
78 int i = recv (s, buf, len, 0);
81 len -= i, buf += i, ret += i;
89 * Read and decrypt one incoming SSH packet.
91 static void get_packet(void)
102 ret = s_read(buf, 4);
109 len = GET_32BIT(buf);
112 if (len == 0x52656d6f) {
119 len -= 5; /* type and CRC */
122 if (pktin.maxlen < biglen) {
123 pktin.maxlen = biglen;
124 pktin.data = (pktin.data == NULL) ?
125 smalloc(biglen) : srealloc(pktin.data, biglen);
128 ret = s_read(pktin.data, biglen);
136 cipher->decrypt(pktin.data, biglen);
138 pktin.type = pktin.data[pad];
139 pktin.body = pktin.data + pad + 1;
141 if (pktin.type == SSH_MSG_DEBUG) {
143 int len = GET_32BIT(pktin.body);
144 fprintf(stderr, "Remote: ");
145 fwrite(pktin.body + 4, len, 1, stderr);
146 fprintf(stderr, "\n");
150 if (pktin.type == SSH_MSG_IGNORE) {
155 static void s_wrpkt_start(int type, int len) {
158 len += 5; /* type and CRC */
162 pktout.length = len-5;
163 if (pktout.maxlen < biglen) {
164 pktout.maxlen = biglen;
165 pktout.data = (pktout.data == NULL ? malloc(biglen+4) :
166 realloc(pktout.data, biglen+4));
168 fatalbox("Out of memory");
172 pktout.body = pktout.data+4+pad+1;
175 static void s_wrpkt(void) {
176 int pad, len, biglen, i;
179 len = pktout.length + 5; /* type and CRC */
183 pktout.body[-1] = pktout.type;
184 for (i=0; i<pad; i++)
185 pktout.data[i+4] = random_byte();
186 crc = crc32(pktout.data+4, biglen-4);
187 PUT_32BIT(pktout.data+biglen, crc);
188 PUT_32BIT(pktout.data, len);
191 cipher->encrypt(pktout.data+4, biglen);
193 s_write(pktout.data, biglen+4);
196 static int do_ssh_init(void) {
204 while (s_read(&c, 1) == 1) {
205 if (c == 'S' && i < 2) i++;
206 else if (c == 'S' && i == 2) i = 2;
207 else if (c == 'H' && i == 2) break;
211 if (s_read(&c,1) != 1 || c != 'S') return 0;
212 if (s_read(&c,1) != 1 || c != 'S') return 0;
213 if (s_read(&c,1) != 1 || c != 'H') return 0;
215 if (s_read(&c,1) != 1 || c != '-') return 0;
218 if (s_read(&c,1) != 1)
224 } else if (i < sizeof(version)-1)
231 sprintf(vstring, "SSH-%s-7.7.7\n",
232 (strcmp(version, "1.5") <= 0 ? version : "1.5"));
233 s_write(vstring, strlen(vstring));
239 * Login on the server and request execution of the command.
241 static void ssh_login(char *username, char *cmd)
244 unsigned char session_id[16];
245 unsigned char *rsabuf, *keystr1, *keystr2;
246 unsigned char cookie[8];
247 struct RSAKey servkey, hostkey;
248 struct MD5Context md5c;
249 unsigned long supported_ciphers_mask;
252 extern struct ssh_cipher ssh_3des;
253 extern struct ssh_cipher ssh_blowfish;
257 if (pktin.type != SSH_SMSG_PUBLIC_KEY)
258 fatalbox("Public key packet not received");
260 memcpy(cookie, pktin.body, 8);
264 i = makekey(pktin.body+8, &servkey, &keystr1);
265 j = makekey(pktin.body+8+i, &hostkey, &keystr2);
267 supported_ciphers_mask = GET_32BIT(pktin.body+12+i+j);
269 MD5Update(&md5c, keystr2, hostkey.bytes);
270 MD5Update(&md5c, keystr1, servkey.bytes);
271 MD5Update(&md5c, pktin.body, 8);
273 MD5Final(session_id, &md5c);
276 session_key[i] = random_byte();
278 len = (hostkey.bytes > servkey.bytes ? hostkey.bytes : servkey.bytes);
280 rsabuf = malloc(len);
282 fatalbox("Out of memory");
285 * Verify the host key.
289 * First format the key into a string.
291 int len = rsastr_len(&hostkey);
292 char *keystr = malloc(len);
294 fatalbox("Out of memory");
295 rsastr_fmt(keystr, &hostkey);
296 verify_ssh_host_key(savedhost, keystr);
300 for (i=0; i<32; i++) {
301 rsabuf[i] = session_key[i];
303 rsabuf[i] ^= session_id[i];
306 if (hostkey.bytes > servkey.bytes) {
307 rsaencrypt(rsabuf, 32, &servkey);
308 rsaencrypt(rsabuf, servkey.bytes, &hostkey);
310 rsaencrypt(rsabuf, 32, &hostkey);
311 rsaencrypt(rsabuf, hostkey.bytes, &servkey);
314 cipher_type = cfg.cipher == CIPHER_BLOWFISH ? SSH_CIPHER_BLOWFISH :
316 if ((supported_ciphers_mask & (1 << cipher_type)) == 0) {
317 fprintf(stderr, "Selected cipher not supported, falling back to 3DES\n");
318 cipher_type = SSH_CIPHER_3DES;
321 s_wrpkt_start(SSH_CMSG_SESSION_KEY, len+15);
322 pktout.body[0] = cipher_type;
323 memcpy(pktout.body+1, cookie, 8);
324 pktout.body[9] = (len*8) >> 8;
325 pktout.body[10] = (len*8) & 0xFF;
326 memcpy(pktout.body+11, rsabuf, len);
327 pktout.body[len+11] = pktout.body[len+12] = 0; /* protocol flags */
328 pktout.body[len+13] = pktout.body[len+14] = 0;
333 cipher = cipher_type == SSH_CIPHER_BLOWFISH ? &ssh_blowfish :
335 cipher->sesskey(session_key);
339 if (pktin.type != SSH_SMSG_SUCCESS)
340 fatalbox("Encryption not successfully enabled");
343 fprintf(stderr, "Logging in as \"%s\".\n", username);
344 s_wrpkt_start(SSH_CMSG_USER, 4+strlen(username));
345 pktout.body[0] = pktout.body[1] = pktout.body[2] = 0;
346 pktout.body[3] = strlen(username);
347 memcpy(pktout.body+4, username, strlen(username));
352 while (pktin.type == SSH_SMSG_FAILURE) {
355 sprintf(prompt, "%s@%s's password: ", username, savedhost);
356 ssh_get_password(prompt, password, 100);
357 s_wrpkt_start(SSH_CMSG_AUTH_PASSWORD, 4+strlen(password));
358 pktout.body[0] = pktout.body[1] = pktout.body[2] = 0;
359 pktout.body[3] = strlen(password);
360 memcpy(pktout.body+4, password, strlen(password));
362 memset(password, 0, strlen(password));
364 if (pktin.type == SSH_SMSG_FAILURE) {
365 fprintf(stderr, "Access denied\n");
366 } else if (pktin.type != SSH_SMSG_SUCCESS) {
367 fatalbox("Strange packet received, type %d", pktin.type);
371 /* Execute command */
373 fprintf(stderr, "Sending command: %s\n", cmd);
375 s_wrpkt_start(SSH_CMSG_EXEC_CMD, 4+i);
376 PUT_32BIT(pktout.body, i);
377 memcpy(pktout.body+4, cmd, i);
383 * Receive a block of data over the SSH link. Block until
384 * all data is available. Return nr of bytes read (0 if lost connection).
386 int ssh_recv(unsigned char *buf, int len)
388 static int pending_input_len = 0;
389 static unsigned char *pending_input_ptr;
392 if (pending_input_len >= to_read) {
393 memcpy(buf, pending_input_ptr, to_read);
394 pending_input_ptr += to_read;
395 pending_input_len -= to_read;
399 if (pending_input_len > 0) {
400 memcpy(buf, pending_input_ptr, pending_input_len);
401 buf += pending_input_len;
402 to_read -= pending_input_len;
403 pending_input_len = 0;
406 if (s == INVALID_SOCKET)
408 while (to_read > 0) {
410 if (s == INVALID_SOCKET)
412 if (pktin.type == SSH_SMSG_STDOUT_DATA) {
413 int plen = GET_32BIT(pktin.body);
414 if (plen <= to_read) {
415 memcpy(buf, pktin.body + 4, plen);
419 memcpy(buf, pktin.body + 4, to_read);
420 pending_input_len = plen - to_read;
421 pending_input_ptr = pktin.body + 4 + to_read;
424 } else if (pktin.type == SSH_SMSG_STDERR_DATA) {
425 int plen = GET_32BIT(pktin.body);
426 fwrite(pktin.body + 4, plen, 1, stderr);
427 } else if (pktin.type == SSH_MSG_DISCONNECT) {
428 } else if (pktin.type == SSH_SMSG_SUCCESS ||
429 pktin.type == SSH_SMSG_FAILURE) {
430 } else if (pktin.type == SSH_SMSG_EXIT_STATUS) {
432 fprintf(stderr, "Remote exit status %d\n",
433 GET_32BIT(pktin.body));
434 s_wrpkt_start(SSH_CMSG_EXIT_CONFIRMATION, 0);
437 fprintf(stderr, "Closing connection\n");
448 * Send a block of data over the SSH link.
449 * Block until all data is sent.
451 void ssh_send(unsigned char *buf, int len)
453 if (s == INVALID_SOCKET)
455 s_wrpkt_start(SSH_CMSG_STDIN_DATA, 4 + len);
456 PUT_32BIT(pktout.body, len);
457 memcpy(pktout.body + 4, buf, len);
463 * Send an EOF notification to the server.
465 void ssh_send_eof(void)
467 if (s == INVALID_SOCKET)
469 s_wrpkt_start(SSH_CMSG_EOF, 0);
475 * Set up the connection, login on the remote host and
476 * start execution of a command.
478 * Returns an error message, or NULL on success.
480 * Also places the canonical host name into `realhost'.
482 char *ssh_init(char *host, int port, char *cmd, char **realhost) {
491 savedhost = malloc(1+strlen(host));
493 fatalbox("Out of memory");
494 strcpy(savedhost, host);
506 if ( (a = inet_addr(host)) == (unsigned long) INADDR_NONE) {
507 if ( (h = gethostbyname(host)) == NULL)
508 switch (WSAGetLastError()) {
509 case WSAENETDOWN: return "Network is down";
510 case WSAHOST_NOT_FOUND: case WSANO_DATA:
511 return "Host does not exist";
512 case WSATRY_AGAIN: return "Host not found";
513 default: return "gethostbyname: unknown error";
515 memcpy (&a, h->h_addr, sizeof(a));
516 *realhost = h->h_name;
525 port = 22; /* default ssh port */
530 s = socket(AF_INET, SOCK_STREAM, 0);
531 if (s == INVALID_SOCKET)
532 switch (WSAGetLastError()) {
533 case WSAENETDOWN: return "Network is down";
534 case WSAEAFNOSUPPORT: return "TCP/IP support not present";
535 default: return "socket(): unknown error";
539 * Bind to local address.
541 addr.sin_family = AF_INET;
542 addr.sin_addr.s_addr = htonl(INADDR_ANY);
543 addr.sin_port = htons(0);
544 if (bind (s, (struct sockaddr *)&addr, sizeof(addr)) == SOCKET_ERROR)
545 switch (WSAGetLastError()) {
546 case WSAENETDOWN: return "Network is down";
547 default: return "bind(): unknown error";
551 * Connect to remote address.
553 addr.sin_addr.s_addr = htonl(a);
554 addr.sin_port = htons((short)port);
555 if (connect (s, (struct sockaddr *)&addr, sizeof(addr)) == SOCKET_ERROR)
556 switch (WSAGetLastError()) {
557 case WSAENETDOWN: return "Network is down";
558 case WSAECONNREFUSED: return "Connection refused";
559 case WSAENETUNREACH: return "Network is unreachable";
560 case WSAEHOSTUNREACH: return "No route to host";
561 default: return "connect(): unknown error";
565 send(s, "connect ", 8, 0);
566 send(s, FWhost, strlen(FWhost), 0);
569 sprintf(buf, " %d\n", FWport);
570 send (s, buf, strlen(buf), 0);
577 return "Protocol initialisation error";
579 ssh_login(cfg.username, cmd);