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putty
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putty/ssh.c

723 строки
17 KiB
C
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#include <stdio.h>
#include <stdlib.h>
#include <winsock.h>
#include "putty.h"
#ifndef FALSE
#define FALSE 0
#endif
#ifndef TRUE
#define TRUE 1
#endif
#include "ssh.h"
/* Coroutine mechanics for the sillier bits of the code */
#define crBegin1 static int crLine = 0;
#define crBegin2 switch(crLine) { case 0:;
#define crBegin crBegin1; crBegin2;
#define crFinish(z) } crLine = 0; return (z)
#define crFinishV } crLine = 0; return
#define crReturn(z) \
do {\
crLine=__LINE__; return (z); case __LINE__:;\
} while (0)
#define crReturnV \
do {\
crLine=__LINE__; return; case __LINE__:;\
} while (0)
#define crStop(z) do{ crLine = 0; return (z); }while(0)
#define crStopV do{ crLine = 0; return; }while(0)
#ifndef FALSE
#define FALSE 0
#endif
#ifndef TRUE
#define TRUE 1
#endif
static SOCKET s = INVALID_SOCKET;
static unsigned char session_key[32];
static struct ssh_cipher *cipher = NULL;
static char *savedhost;
static enum {
SSH_STATE_BEFORE_SIZE,
SSH_STATE_INTERMED,
SSH_STATE_SESSION,
SSH_STATE_CLOSED
} ssh_state = SSH_STATE_BEFORE_SIZE;
static int size_needed = FALSE;
static void s_write (char *buf, int len) {
while (len > 0) {
int i = send (s, buf, len, 0);
if (i > 0)
len -= i, buf += i;
}
}
static int s_read (char *buf, int len) {
int ret = 0;
while (len > 0) {
int i = recv (s, buf, len, 0);
if (i > 0)
len -= i, buf += i, ret += i;
else
return i;
}
return ret;
}
static void c_write (char *buf, int len) {
while (len--) {
int new_head = (inbuf_head + 1) & INBUF_MASK;
if (new_head != inbuf_reap) {
inbuf[inbuf_head] = *buf++;
inbuf_head = new_head;
}
}
}
struct Packet {
long length;
int type;
unsigned long crc;
unsigned char *data;
unsigned char *body;
long maxlen;
};
static struct Packet pktin = { 0, 0, 0, NULL, 0 };
static struct Packet pktout = { 0, 0, 0, NULL, 0 };
static void ssh_protocol(unsigned char *in, int inlen, int ispkt);
static void ssh_size(void);
static void ssh_gotdata(unsigned char *data, int datalen) {
static long len, biglen, to_read;
static unsigned char *p;
static int i, pad;
crBegin;
while (1) {
for (i = len = 0; i < 4; i++) {
while (datalen == 0)
crReturnV;
len = (len << 8) + *data;
data++, datalen--;
}
#ifdef FWHACK
if (len == 0x52656d6f) { /* "Remo"te server has closed ... */
len = 0x300; /* big enough to carry to end */
}
#endif
pad = 8 - (len%8);
biglen = len + pad;
len -= 5; /* type and CRC */
pktin.length = len;
if (pktin.maxlen < biglen) {
pktin.maxlen = biglen;
pktin.data = (pktin.data == NULL ? malloc(biglen) :
realloc(pktin.data, biglen));
if (!pktin.data)
fatalbox("Out of memory");
}
p = pktin.data, to_read = biglen;
while (to_read > 0) {
static int chunk;
chunk = to_read;
while (datalen == 0)
crReturnV;
if (chunk > datalen)
chunk = datalen;
memcpy(p, data, chunk);
data += chunk;
datalen -= chunk;
p += chunk;
to_read -= chunk;
}
if (cipher)
cipher->decrypt(pktin.data, biglen);
pktin.type = pktin.data[pad];
pktin.body = pktin.data+pad+1;
if (pktin.type == 36) { /* SSH_MSG_DEBUG */
/* FIXME: log it */
} else
ssh_protocol(NULL, 0, 1);
}
crFinishV;
}
static void s_wrpkt_start(int type, int len) {
int pad, biglen;
len += 5; /* type and CRC */
pad = 8 - (len%8);
biglen = len + pad;
pktout.length = len-5;
if (pktout.maxlen < biglen) {
pktout.maxlen = biglen;
pktout.data = (pktout.data == NULL ? malloc(biglen+4) :
realloc(pktout.data, biglen+4));
if (!pktout.data)
fatalbox("Out of memory");
}
pktout.type = type;
pktout.body = pktout.data+4+pad+1;
}
static void s_wrpkt(void) {
int pad, len, biglen, i;
unsigned long crc;
len = pktout.length + 5; /* type and CRC */
pad = 8 - (len%8);
biglen = len + pad;
pktout.body[-1] = pktout.type;
for (i=0; i<pad; i++)
pktout.data[i+4] = random_byte();
crc = crc32(pktout.data+4, biglen-4);
pktout.data[biglen+0] = (unsigned char) ((crc >> 24) & 0xFF);
pktout.data[biglen+1] = (unsigned char) ((crc >> 16) & 0xFF);
pktout.data[biglen+2] = (unsigned char) ((crc >> 8) & 0xFF);
pktout.data[biglen+3] = (unsigned char) (crc & 0xFF);
pktout.data[0] = (len >> 24) & 0xFF;
pktout.data[1] = (len >> 16) & 0xFF;
pktout.data[2] = (len >> 8) & 0xFF;
pktout.data[3] = len & 0xFF;
if (cipher)
cipher->encrypt(pktout.data+4, biglen);
s_write(pktout.data, biglen+4);
}
static int do_ssh_init(void) {
char c;
char version[10];
char vstring[40];
int i;
#ifdef FWHACK
i = 0;
while (s_read(&c, 1) == 1) {
if (c == 'S' && i < 2) i++;
else if (c == 'S' && i == 2) i = 2;
else if (c == 'H' && i == 2) break;
else i = 0;
}
#else
if (s_read(&c,1) != 1 || c != 'S') return 0;
if (s_read(&c,1) != 1 || c != 'S') return 0;
if (s_read(&c,1) != 1 || c != 'H') return 0;
#endif
if (s_read(&c,1) != 1 || c != '-') return 0;
i = 0;
while (1) {
if (s_read(&c,1) != 1)
return 0;
if (i >= 0) {
if (c == '-') {
version[i] = '\0';
i = -1;
} else if (i < sizeof(version)-1)
version[i++] = c;
}
else if (c == '\n')
break;
}
sprintf(vstring, "SSH-%s-7.7.7\n",
(strcmp(version, "1.5") <= 0 ? version : "1.5"));
s_write(vstring, strlen(vstring));
return 1;
}
static void ssh_protocol(unsigned char *in, int inlen, int ispkt) {
int i, j, len;
unsigned char session_id[16];
unsigned char *rsabuf, *keystr1, *keystr2;
unsigned char cookie[8];
struct RSAKey servkey, hostkey;
struct MD5Context md5c;
unsigned long supported_ciphers_mask;
int cipher_type;
extern struct ssh_cipher ssh_3des;
extern struct ssh_cipher ssh_blowfish;
crBegin;
random_init();
while (!ispkt)
crReturnV;
if (pktin.type != 2)
fatalbox("Public key packet not received");
memcpy(cookie, pktin.body, 8);
MD5Init(&md5c);
i = makekey(pktin.body+8, &servkey, &keystr1);
j = makekey(pktin.body+8+i, &hostkey, &keystr2);
supported_ciphers_mask = (pktin.body[12+i+j] << 24) |
(pktin.body[13+i+j] << 16) |
(pktin.body[14+i+j] << 8) |
(pktin.body[15+i+j]);
MD5Update(&md5c, keystr2, hostkey.bytes);
MD5Update(&md5c, keystr1, servkey.bytes);
MD5Update(&md5c, pktin.body, 8);
MD5Final(session_id, &md5c);
for (i=0; i<32; i++)
session_key[i] = random_byte();
len = (hostkey.bytes > servkey.bytes ? hostkey.bytes : servkey.bytes);
rsabuf = malloc(len);
if (!rsabuf)
fatalbox("Out of memory");
verify_ssh_host_key(savedhost, &hostkey);
for (i=0; i<32; i++) {
rsabuf[i] = session_key[i];
if (i < 16)
rsabuf[i] ^= session_id[i];
}
if (hostkey.bytes > servkey.bytes) {
rsaencrypt(rsabuf, 32, &servkey);
rsaencrypt(rsabuf, servkey.bytes, &hostkey);
} else {
rsaencrypt(rsabuf, 32, &hostkey);
rsaencrypt(rsabuf, hostkey.bytes, &servkey);
}
cipher_type = cfg.cipher == CIPHER_BLOWFISH ? SSH_CIPHER_BLOWFISH :
SSH_CIPHER_3DES;
if ((supported_ciphers_mask & (1 << cipher_type)) == 0) {
c_write("Selected cipher not supported, falling back to 3DES\r\n", 53);
cipher_type = SSH_CIPHER_3DES;
}
s_wrpkt_start(3, len+15);
pktout.body[0] = cipher_type;
memcpy(pktout.body+1, cookie, 8);
pktout.body[9] = (len*8) >> 8;
pktout.body[10] = (len*8) & 0xFF;
memcpy(pktout.body+11, rsabuf, len);
pktout.body[len+11] = pktout.body[len+12] = 0; /* protocol flags */
pktout.body[len+13] = pktout.body[len+14] = 0;
s_wrpkt();
free(rsabuf);
cipher = cipher_type == SSH_CIPHER_BLOWFISH ? &ssh_blowfish :
&ssh_3des;
cipher->sesskey(session_key);
do { crReturnV; } while (!ispkt);
if (pktin.type != 14)
fatalbox("Encryption not successfully enabled");
fflush(stdout);
{
static char username[100];
static int pos = 0;
static char c;
if (!*cfg.username) {
c_write("login as: ", 10);
while (pos >= 0) {
do { crReturnV; } while (ispkt);
while (inlen--) switch (c = *in++) {
case 10: case 13:
username[pos] = 0;
pos = -1;
break;
case 8: case 127:
if (pos > 0) {
c_write("\b \b", 3);
pos--;
}
break;
case 21: case 27:
while (pos > 0) {
c_write("\b \b", 3);
pos--;
}
break;
case 3: case 4:
random_save_seed();
exit(0);
break;
default:
if (c >= ' ' && c <= '~' && pos < 40) {
username[pos++] = c;
c_write(&c, 1);
}
break;
}
}
c_write("\r\n", 2);
username[strcspn(username, "\n\r")] = '\0';
} else {
char stuff[200];
strncpy(username, cfg.username, 99);
username[99] = '\0';
sprintf(stuff, "Sent username \"%s\".\r\n", username);
c_write(stuff, strlen(stuff));
}
s_wrpkt_start(4, 4+strlen(username));
pktout.body[0] = pktout.body[1] = pktout.body[2] = 0;
pktout.body[3] = strlen(username);
memcpy(pktout.body+4, username, strlen(username));
s_wrpkt();
}
do { crReturnV; } while (!ispkt);
while (pktin.type == 15) {
static char password[100];
static int pos;
static char c;
c_write("password: ", 10);
pos = 0;
while (pos >= 0) {
do { crReturnV; } while (ispkt);
while (inlen--) switch (c = *in++) {
case 10: case 13:
password[pos] = 0;
pos = -1;
break;
case 8: case 127:
if (pos > 0)
pos--;
break;
case 21: case 27:
pos = 0;
break;
case 3: case 4:
random_save_seed();
exit(0);
break;
default:
if (c >= ' ' && c <= '~' && pos < 40)
password[pos++] = c;
break;
}
}
c_write("\r\n", 2);
s_wrpkt_start(9, 4+strlen(password));
pktout.body[0] = pktout.body[1] = pktout.body[2] = 0;
pktout.body[3] = strlen(password);
memcpy(pktout.body+4, password, strlen(password));
s_wrpkt();
memset(password, 0, strlen(password));
do { crReturnV; } while (!ispkt);
if (pktin.type == 15) {
c_write("Access denied\r\n", 15);
} else if (pktin.type != 14) {
fatalbox("Strange packet received, type %d", pktin.type);
}
}
if (!cfg.nopty) {
i = strlen(cfg.termtype);
s_wrpkt_start(10, i+5*4+1);
pktout.body[0] = (i >> 24) & 0xFF;
pktout.body[1] = (i >> 16) & 0xFF;
pktout.body[2] = (i >> 8) & 0xFF;
pktout.body[3] = i & 0xFF;
memcpy(pktout.body+4, cfg.termtype, i);
i += 4;
pktout.body[i++] = (rows >> 24) & 0xFF;
pktout.body[i++] = (rows >> 16) & 0xFF;
pktout.body[i++] = (rows >> 8) & 0xFF;
pktout.body[i++] = rows & 0xFF;
pktout.body[i++] = (cols >> 24) & 0xFF;
pktout.body[i++] = (cols >> 16) & 0xFF;
pktout.body[i++] = (cols >> 8) & 0xFF;
pktout.body[i++] = cols & 0xFF;
memset(pktout.body+i, 0, 9); /* 0 pixwidth, 0 pixheight, 0.b endofopt */
s_wrpkt();
ssh_state = SSH_STATE_INTERMED;
do { crReturnV; } while (!ispkt);
if (pktin.type != 14 && pktin.type != 15) {
fatalbox("Protocol confusion");
} else if (pktin.type == 15) {
c_write("Server refused to allocate pty\r\n", 32);
}
}
s_wrpkt_start(12, 0);
s_wrpkt();
ssh_state = SSH_STATE_SESSION;
if (size_needed)
ssh_size();
while (1) {
crReturnV;
if (ispkt) {
if (pktin.type == 17 || pktin.type == 18) {
long len = 0;
for (i = 0; i < 4; i++)
len = (len << 8) + pktin.body[i];
c_write(pktin.body+4, len);
} else if (pktin.type == 1) {
/* SSH_MSG_DISCONNECT */
ssh_state = SSH_STATE_CLOSED;
} else if (pktin.type == 14) {
/* SSH_MSG_SUCCESS: may be from EXEC_SHELL on some servers */
} else if (pktin.type == 15) {
/* SSH_MSG_FAILURE: may be from EXEC_SHELL on some servers
* if no pty is available or in other odd cases. Ignore */
} else if (pktin.type == 20) {
/* EXITSTATUS */
s_wrpkt_start(33, 0);
s_wrpkt();
} else {
fatalbox("Strange packet received: type %d", pktin.type);
}
} else {
s_wrpkt_start(16, 4+inlen);
pktout.body[0] = (inlen >> 24) & 0xFF;
pktout.body[1] = (inlen >> 16) & 0xFF;
pktout.body[2] = (inlen >> 8) & 0xFF;
pktout.body[3] = inlen & 0xFF;
memcpy(pktout.body+4, in, inlen);
s_wrpkt();
}
}
crFinishV;
}
/*
* Called to set up the connection. Will arrange for WM_NETEVENT
* messages to be passed to the specified window, whose window
* procedure should then call telnet_msg().
*
* Returns an error message, or NULL on success.
*
* Also places the canonical host name into `realhost'.
*/
static char *ssh_init (HWND hwnd, char *host, int port, char **realhost) {
SOCKADDR_IN addr;
struct hostent *h;
unsigned long a;
#ifdef FWHACK
char *FWhost;
int FWport;
#endif
savedhost = malloc(1+strlen(host));
if (!savedhost)
fatalbox("Out of memory");
strcpy(savedhost, host);
#ifdef FWHACK
FWhost = host;
FWport = port;
host = FWSTR;
port = 23;
#endif
/*
* Try to find host.
*/
if ( (a = inet_addr(host)) == (unsigned long) INADDR_NONE) {
if ( (h = gethostbyname(host)) == NULL)
switch (WSAGetLastError()) {
case WSAENETDOWN: return "Network is down";
case WSAHOST_NOT_FOUND: case WSANO_DATA:
return "Host does not exist";
case WSATRY_AGAIN: return "Host not found";
default: return "gethostbyname: unknown error";
}
memcpy (&a, h->h_addr, sizeof(a));
*realhost = h->h_name;
} else
*realhost = host;
#ifdef FWHACK
*realhost = FWhost;
#endif
a = ntohl(a);
if (port < 0)
port = 22; /* default ssh port */
/*
* Open socket.
*/
s = socket(AF_INET, SOCK_STREAM, 0);
if (s == INVALID_SOCKET)
switch (WSAGetLastError()) {
case WSAENETDOWN: return "Network is down";
case WSAEAFNOSUPPORT: return "TCP/IP support not present";
default: return "socket(): unknown error";
}
/*
* Bind to local address.
*/
addr.sin_family = AF_INET;
addr.sin_addr.s_addr = htonl(INADDR_ANY);
addr.sin_port = htons(0);
if (bind (s, (struct sockaddr *)&addr, sizeof(addr)) == SOCKET_ERROR)
switch (WSAGetLastError()) {
case WSAENETDOWN: return "Network is down";
default: return "bind(): unknown error";
}
/*
* Connect to remote address.
*/
addr.sin_addr.s_addr = htonl(a);
addr.sin_port = htons((short)port);
if (connect (s, (struct sockaddr *)&addr, sizeof(addr)) == SOCKET_ERROR)
switch (WSAGetLastError()) {
case WSAENETDOWN: return "Network is down";
case WSAECONNREFUSED: return "Connection refused";
case WSAENETUNREACH: return "Network is unreachable";
case WSAEHOSTUNREACH: return "No route to host";
default: return "connect(): unknown error";
}
#ifdef FWHACK
send(s, "connect ", 8, 0);
send(s, FWhost, strlen(FWhost), 0);
{
char buf[20];
sprintf(buf, " %d\n", FWport);
send (s, buf, strlen(buf), 0);
}
#endif
if (!do_ssh_init())
return "Protocol initialisation error";
if (WSAAsyncSelect (s, hwnd, WM_NETEVENT, FD_READ | FD_CLOSE) == SOCKET_ERROR)
switch (WSAGetLastError()) {
case WSAENETDOWN: return "Network is down";
default: return "WSAAsyncSelect(): unknown error";
}
return NULL;
}
/*
* Process a WM_NETEVENT message. Will return 0 if the connection
* has closed, or <0 for a socket error.
*/
static int ssh_msg (WPARAM wParam, LPARAM lParam) {
int ret;
char buf[256];
if (s == INVALID_SOCKET) /* how the hell did we get here?! */
return -5000;
if (WSAGETSELECTERROR(lParam) != 0)
return -WSAGETSELECTERROR(lParam);
switch (WSAGETSELECTEVENT(lParam)) {
case FD_READ:
ret = recv(s, buf, sizeof(buf), 0);
if (ret < 0 && WSAGetLastError() == WSAEWOULDBLOCK)
return 1;
if (ret < 0) /* any _other_ error */
return -10000-WSAGetLastError();
if (ret == 0) {
s = INVALID_SOCKET;
return 0; /* can't happen, in theory */
}
ssh_gotdata (buf, ret);
return 1;
case FD_CLOSE:
s = INVALID_SOCKET;
ssh_state = SSH_STATE_CLOSED;
return 0;
}
return 1; /* shouldn't happen, but WTF */
}
/*
* Called to send data down the Telnet connection.
*/
static void ssh_send (char *buf, int len) {
if (s == INVALID_SOCKET)
return;
ssh_protocol(buf, len, 0);
}
/*
* Called to set the size of the window from Telnet's POV.
*/
static void ssh_size(void) {
switch (ssh_state) {
case SSH_STATE_BEFORE_SIZE:
case SSH_STATE_CLOSED:
break; /* do nothing */
case SSH_STATE_INTERMED:
size_needed = TRUE; /* buffer for later */
break;
case SSH_STATE_SESSION:
if (!cfg.nopty) {
s_wrpkt_start(11, 16);
pktout.body[0] = (rows >> 24) & 0xFF;
pktout.body[1] = (rows >> 16) & 0xFF;
pktout.body[2] = (rows >> 8) & 0xFF;
pktout.body[3] = rows & 0xFF;
pktout.body[4] = (cols >> 24) & 0xFF;
pktout.body[5] = (cols >> 16) & 0xFF;
pktout.body[6] = (cols >> 8) & 0xFF;
pktout.body[7] = cols & 0xFF;
memset(pktout.body+8, 0, 8);
s_wrpkt();
}
}
}
/*
* (Send Telnet special codes)
*/
static void ssh_special (Telnet_Special code) {
/* do nothing */
}
Backend ssh_backend = {
ssh_init,
ssh_msg,
ssh_send,
ssh_size,
ssh_special
};
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