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- #include "ssh.h"
- static ulong sum32(ulong, void*, int);
- char *msgnames[] =
- {
- /* 0 */
- "SSH_MSG_NONE",
- "SSH_MSG_DISCONNECT",
- "SSH_SMSG_PUBLIC_KEY",
- "SSH_CMSG_SESSION_KEY",
- "SSH_CMSG_USER",
- "SSH_CMSG_AUTH_RHOSTS",
- "SSH_CMSG_AUTH_RSA",
- "SSH_SMSG_AUTH_RSA_CHALLENGE",
- "SSH_CMSG_AUTH_RSA_RESPONSE",
- "SSH_CMSG_AUTH_PASSWORD",
- /* 10 */
- "SSH_CMSG_REQUEST_PTY",
- "SSH_CMSG_WINDOW_SIZE",
- "SSH_CMSG_EXEC_SHELL",
- "SSH_CMSG_EXEC_CMD",
- "SSH_SMSG_SUCCESS",
- "SSH_SMSG_FAILURE",
- "SSH_CMSG_STDIN_DATA",
- "SSH_SMSG_STDOUT_DATA",
- "SSH_SMSG_STDERR_DATA",
- "SSH_CMSG_EOF",
- /* 20 */
- "SSH_SMSG_EXITSTATUS",
- "SSH_MSG_CHANNEL_OPEN_CONFIRMATION",
- "SSH_MSG_CHANNEL_OPEN_FAILURE",
- "SSH_MSG_CHANNEL_DATA",
- "SSH_MSG_CHANNEL_INPUT_EOF",
- "SSH_MSG_CHANNEL_OUTPUT_CLOSED",
- "SSH_MSG_UNIX_DOMAIN_X11_FORWARDING (obsolete)",
- "SSH_SMSG_X11_OPEN",
- "SSH_CMSG_PORT_FORWARD_REQUEST",
- "SSH_MSG_PORT_OPEN",
- /* 30 */
- "SSH_CMSG_AGENT_REQUEST_FORWARDING",
- "SSH_SMSG_AGENT_OPEN",
- "SSH_MSG_IGNORE",
- "SSH_CMSG_EXIT_CONFIRMATION",
- "SSH_CMSG_X11_REQUEST_FORWARDING",
- "SSH_CMSG_AUTH_RHOSTS_RSA",
- "SSH_MSG_DEBUG",
- "SSH_CMSG_REQUEST_COMPRESSION",
- "SSH_CMSG_MAX_PACKET_SIZE",
- "SSH_CMSG_AUTH_TIS",
- /* 40 */
- "SSH_SMSG_AUTH_TIS_CHALLENGE",
- "SSH_CMSG_AUTH_TIS_RESPONSE",
- "SSH_CMSG_AUTH_KERBEROS",
- "SSH_SMSG_AUTH_KERBEROS_RESPONSE",
- "SSH_CMSG_HAVE_KERBEROS_TGT"
- };
- void
- badmsg(Msg *m, int want)
- {
- char *s, buf[20+ERRMAX];
- if(m==nil){
- snprint(buf, sizeof buf, "<early eof: %r>");
- s = buf;
- }else{
- snprint(buf, sizeof buf, "<unknown type %d>", m->type);
- s = buf;
- if(0 <= m->type && m->type < nelem(msgnames))
- s = msgnames[m->type];
- }
- if(want)
- error("got %s message expecting %s", s, msgnames[want]);
- error("got unexpected %s message", s);
- }
- Msg*
- allocmsg(Conn *c, int type, int len)
- {
- uchar *p;
- Msg *m;
- if(len > 256*1024)
- abort();
- m = (Msg*)emalloc(sizeof(Msg)+4+8+1+len+4);
- setmalloctag(m, getcallerpc(&c));
- p = (uchar*)&m[1];
- m->c = c;
- m->bp = p;
- m->ep = p+len;
- m->wp = p;
- m->type = type;
- return m;
- }
- static Msg*
- recvmsg0(Conn *c)
- {
- int pad;
- uchar *p, buf[4];
- ulong crc, crc0, len;
- Msg *m;
- if(readn(c->fd[0], buf, 4) != 4){
- werrstr("short net read: %r");
- return nil;
- }
- len = LONG(buf);
- if(len > 256*1024){
- werrstr("packet size far too big: %.8lux", len);
- return nil;
- }
- pad = 8 - len%8;
- m = (Msg*)emalloc(sizeof(Msg)+pad+len);
- setmalloctag(m, getcallerpc(&c));
- m->c = c;
- m->bp = (uchar*)&m[1];
- m->ep = m->bp + pad+len-4; /* -4: don't include crc */
- m->rp = m->bp;
- if(readn(c->fd[0], m->bp, pad+len) != pad+len){
- werrstr("short net read: %r");
- free(m);
- return nil;
- }
- if(c->cipher)
- c->cipher->decrypt(c->cstate, m->bp, len+pad);
- crc = sum32(0, m->bp, pad+len-4);
- p = m->bp + pad+len-4;
- crc0 = LONG(p);
- if(crc != crc0){
- werrstr("bad crc %#lux != %#lux (packet length %lud)", crc, crc0, len);
- free(m);
- return nil;
- }
- m->rp += pad;
- m->type = *m->rp++;
- return m;
- }
- Msg*
- recvmsg(Conn *c, int type)
- {
- Msg *m;
- while((m = recvmsg0(c)) != nil){
- debug(DBG_PROTO, "received %s len %d\n", msgnames[m->type], m->ep - m->rp);
- if(m->type != SSH_MSG_DEBUG && m->type != SSH_MSG_IGNORE)
- break;
- if(m->type == SSH_MSG_DEBUG)
- debug(DBG_PROTO, "remote DEBUG: %s\n", getstring(m));
- free(m);
- }
- if(type && (m==nil || m->type!=type))
- badmsg(m, type);
- setmalloctag(m, getcallerpc(&c));
- return m;
- }
- int
- sendmsg(Msg *m)
- {
- int i, pad;
- uchar *p;
- ulong datalen, len, crc;
- Conn *c;
- datalen = m->wp - m->bp;
- len = datalen + 5;
- pad = 8 - len%8;
- debug(DBG_PROTO, "sending %s len %d\n", msgnames[m->type], datalen);
- p = m->bp;
- memmove(m->bp+4+pad+1, m->bp, datalen); /* slide data to correct position */
- PLONG(p, len);
- p += 4;
- if(m->c->cstate){
- for(i=0; i<pad; i++)
- *p++ = fastrand();
- }else{
- memset(p, 0, pad);
- p += pad;
- }
- *p++ = m->type;
- /* data already in position */
- p += datalen;
- crc = sum32(0, m->bp+4, pad+1+datalen);
- PLONG(p, crc);
- p += 4;
- c = m->c;
- qlock(c);
- if(c->cstate)
- c->cipher->encrypt(c->cstate, m->bp+4, len+pad);
- if(write(c->fd[1], m->bp, p - m->bp) != p-m->bp){
- qunlock(c);
- free(m);
- return -1;
- }
- qunlock(c);
- free(m);
- return 0;
- }
- uchar
- getbyte(Msg *m)
- {
- if(m->rp >= m->ep)
- error(Edecode);
- return *m->rp++;
- }
- ushort
- getshort(Msg *m)
- {
- ushort x;
- if(m->rp+2 > m->ep)
- error(Edecode);
- x = SHORT(m->rp);
- m->rp += 2;
- return x;
- }
- ulong
- getlong(Msg *m)
- {
- ulong x;
- if(m->rp+4 > m->ep)
- error(Edecode);
- x = LONG(m->rp);
- m->rp += 4;
- return x;
- }
- char*
- getstring(Msg *m)
- {
- char *p;
- ulong len;
- /* overwrites length to make room for NUL */
- len = getlong(m);
- if(m->rp+len > m->ep)
- error(Edecode);
- p = (char*)m->rp-1;
- memmove(p, m->rp, len);
- p[len] = '\0';
- return p;
- }
- void*
- getbytes(Msg *m, int n)
- {
- uchar *p;
- if(m->rp+n > m->ep)
- error(Edecode);
- p = m->rp;
- m->rp += n;
- return p;
- }
- mpint*
- getmpint(Msg *m)
- {
- int n;
- n = (getshort(m)+7)/8; /* getshort returns # bits */
- return betomp(getbytes(m, n), n, nil);
- }
- RSApub*
- getRSApub(Msg *m)
- {
- RSApub *key;
- getlong(m);
- key = rsapuballoc();
- if(key == nil)
- error(Ememory);
- key->ek = getmpint(m);
- key->n = getmpint(m);
- setmalloctag(key, getcallerpc(&m));
- return key;
- }
- void
- putbyte(Msg *m, uchar x)
- {
- if(m->wp >= m->ep)
- error(Eencode);
- *m->wp++ = x;
- }
- void
- putshort(Msg *m, ushort x)
- {
- if(m->wp+2 > m->ep)
- error(Eencode);
- PSHORT(m->wp, x);
- m->wp += 2;
- }
- void
- putlong(Msg *m, ulong x)
- {
- if(m->wp+4 > m->ep)
- error(Eencode);
- PLONG(m->wp, x);
- m->wp += 4;
- }
- void
- putstring(Msg *m, char *s)
- {
- int len;
- len = strlen(s);
- putlong(m, len);
- putbytes(m, s, len);
- }
- void
- putbytes(Msg *m, void *a, long n)
- {
- if(m->wp+n > m->ep)
- error(Eencode);
- memmove(m->wp, a, n);
- m->wp += n;
- }
- void
- putmpint(Msg *m, mpint *b)
- {
- int bits, n;
- bits = mpsignif(b);
- putshort(m, bits);
- n = (bits+7)/8;
- if(m->wp+n > m->ep)
- error(Eencode);
- mptobe(b, m->wp, n, nil);
- m->wp += n;
- }
- void
- putRSApub(Msg *m, RSApub *key)
- {
- putlong(m, mpsignif(key->n));
- putmpint(m, key->ek);
- putmpint(m, key->n);
- }
- static ulong crctab[256];
- static void
- initsum32(void)
- {
- ulong crc, poly;
- int i, j;
- poly = 0xEDB88320;
- for(i = 0; i < 256; i++){
- crc = i;
- for(j = 0; j < 8; j++){
- if(crc & 1)
- crc = (crc >> 1) ^ poly;
- else
- crc >>= 1;
- }
- crctab[i] = crc;
- }
- }
- static ulong
- sum32(ulong lcrc, void *buf, int n)
- {
- static int first=1;
- uchar *s = buf;
- ulong crc = lcrc;
- if(first){
- first=0;
- initsum32();
- }
- while(n-- > 0)
- crc = crctab[(crc^*s++)&0xff] ^ (crc>>8);
- return crc;
- }
- mpint*
- rsapad(mpint *b, int n)
- {
- int i, pad, nbuf;
- uchar buf[256];
- mpint *c;
- if(n > sizeof buf)
- error("buffer too small in rsapad");
- nbuf = (mpsignif(b)+7)/8;
- pad = n - nbuf;
- assert(pad >= 3);
- mptobe(b, buf, nbuf, nil);
- memmove(buf+pad, buf, nbuf);
- buf[0] = 0;
- buf[1] = 2;
- for(i=2; i<pad-1; i++)
- buf[i]=1+fastrand()%255;
- buf[pad-1] = 0;
- c = betomp(buf, n, nil);
- memset(buf, 0, sizeof buf);
- return c;
- }
- mpint*
- rsaunpad(mpint *b)
- {
- int i, n;
- uchar buf[256];
- n = (mpsignif(b)+7)/8;
- if(n > sizeof buf)
- error("buffer too small in rsaunpad");
- mptobe(b, buf, n, nil);
- /* the initial zero has been eaten by the betomp -> mptobe sequence */
- if(buf[0] != 2)
- error("bad data in rsaunpad");
- for(i=1; i<n; i++)
- if(buf[i]==0)
- break;
- return betomp(buf+i, n-i, nil);
- }
- void
- mptoberjust(mpint *b, uchar *buf, int len)
- {
- int n;
- n = mptobe(b, buf, len, nil);
- assert(n >= 0);
- if(n < len){
- len -= n;
- memmove(buf+len, buf, n);
- memset(buf, 0, len);
- }
- }
- mpint*
- rsaencryptbuf(RSApub *key, uchar *buf, int nbuf)
- {
- int n;
- mpint *a, *b, *c;
- n = (mpsignif(key->n)+7)/8;
- a = betomp(buf, nbuf, nil);
- b = rsapad(a, n);
- mpfree(a);
- c = rsaencrypt(key, b, nil);
- mpfree(b);
- return c;
- }
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