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#include "ssh.h"
char *cipherlist = "blowfish rc4 3des";
char *authlist = "tis";
void fromnet(Conn*);
void startcmd(Conn*, char*, int*, int*);
int maxmsg = 256*1024;
Cipher *allcipher[] = {
&cipherrc4,
&cipherblowfish,
&cipher3des,
&cipherdes,
&ciphernone,
&ciphertwiddle,
};
Authsrv *allauthsrv[] = {
&authsrvpassword,
&authsrvtis,
};
Cipher*
findcipher(char *name, Cipher **list, int nlist)
{
int i;
for(i=0; i<nlist; i++)
if(strcmp(name, list[i]->name) == 0)
return list[i];
error("unknown cipher %s", name);
return nil;
}
Authsrv*
findauthsrv(char *name, Authsrv **list, int nlist)
{
int i;
for(i=0; i<nlist; i++)
if(strcmp(name, list[i]->name) == 0)
return list[i];
error("unknown authsrv %s", name);
return nil;
}
void
usage(void)
{
fprint(2, "usage: sshserve [-A authlist] [-c cipherlist] client-ip-address\n");
exits("usage");
}
void
main(int argc, char **argv)
{
char *f[16];
int i;
Conn c;
fmtinstall('B', mpfmt);
fmtinstall('H', encodefmt);
atexit(atexitkiller);
atexitkill(getpid());
memset(&c, 0, sizeof c);
ARGBEGIN{
case 'D':
debuglevel = atoi(EARGF(usage()));
break;
case 'A':
authlist = EARGF(usage());
break;
case 'c':
cipherlist = EARGF(usage());
break;
default:
usage();
}ARGEND
if(argc != 1)
usage();
c.host = argv[0];
sshlog("connect from %s", c.host);
/* limit of 768 bits in remote host key? */
c.serverpriv = rsagen(768, 6, 0);
if(c.serverpriv == nil)
sysfatal("rsagen failed: %r");
c.serverkey = &c.serverpriv->pub;
c.nokcipher = getfields(cipherlist, f, nelem(f), 1, ", ");
c.okcipher = emalloc(sizeof(Cipher*)*c.nokcipher);
for(i=0; i<c.nokcipher; i++)
c.okcipher[i] = findcipher(f[i], allcipher, nelem(allcipher));
c.nokauthsrv = getfields(authlist, f, nelem(f), 1, ", ");
c.okauthsrv = emalloc(sizeof(Authsrv*)*c.nokauthsrv);
for(i=0; i<c.nokauthsrv; i++)
c.okauthsrv[i] = findauthsrv(f[i], allauthsrv, nelem(allauthsrv));
sshserverhandshake(&c);
fromnet(&c);
}
void
fromnet(Conn *c)
{
int infd, kidpid, n;
char *cmd;
Msg *m;
infd = kidpid = -1;
for(;;){
m = recvmsg(c, -1);
if(m == nil)
exits(nil);
switch(m->type){
default:
//badmsg(m, 0);
sendmsg(allocmsg(c, SSH_SMSG_FAILURE, 0));
break;
case SSH_MSG_DISCONNECT:
sysfatal("client disconnected");
case SSH_CMSG_REQUEST_PTY:
sendmsg(allocmsg(c, SSH_SMSG_SUCCESS, 0));
break;
case SSH_CMSG_X11_REQUEST_FORWARDING:
sendmsg(allocmsg(c, SSH_SMSG_FAILURE, 0));
break;
case SSH_CMSG_MAX_PACKET_SIZE:
maxmsg = getlong(m);
sendmsg(allocmsg(c, SSH_SMSG_SUCCESS, 0));
break;
case SSH_CMSG_REQUEST_COMPRESSION:
sendmsg(allocmsg(c, SSH_SMSG_FAILURE, 0));
break;
case SSH_CMSG_EXEC_SHELL:
startcmd(c, nil, &kidpid, &infd);
goto InteractiveMode;
case SSH_CMSG_EXEC_CMD:
cmd = getstring(m);
startcmd(c, cmd, &kidpid, &infd);
goto InteractiveMode;
}
free(m);
}
InteractiveMode:
for(;;){
free(m);
m = recvmsg(c, -1);
if(m == nil)
exits(nil);
switch(m->type){
default:
badmsg(m, 0);
case SSH_MSG_DISCONNECT:
postnote(PNGROUP, kidpid, "hangup");
sysfatal("client disconnected");
case SSH_CMSG_STDIN_DATA:
if(infd != 0){
n = getlong(m);
write(infd, getbytes(m, n), n);
}
break;
case SSH_CMSG_EOF:
close(infd);
infd = -1;
break;
case SSH_CMSG_EXIT_CONFIRMATION:
/* sent by some clients as dying breath */
exits(nil);
case SSH_CMSG_WINDOW_SIZE:
/* we don't care */
break;
}
}
}
void
copyout(Conn *c, int fd, int mtype)
{
char buf[8192];
int n, max, pid;
Msg *m;
max = sizeof buf;
if(max > maxmsg - 32) /* 32 is an overestimate of packet overhead */
max = maxmsg - 32;
if(max <= 0)
sysfatal("maximum message size too small");
switch(pid = rfork(RFPROC|RFMEM|RFNOWAIT)){
case -1:
sysfatal("fork: %r");
case 0:
break;
default:
atexitkill(pid);
return;
}
while((n = read(fd, buf, max)) > 0){
m = allocmsg(c, mtype, 4+n);
putlong(m, n);
putbytes(m, buf, n);
sendmsg(m);
}
exits(nil);
}
void
startcmd(Conn *c, char *cmd, int *kidpid, int *kidin)
{
int i, pid, kpid;
int pfd[3][2];
char *dir;
char *sysname, *tz;
Msg *m;
Waitmsg *w;
for(i=0; i<3; i++)
if(pipe(pfd[i]) < 0)
sysfatal("pipe: %r");
sysname = getenv("sysname");
tz = getenv("timezone");
switch(pid = rfork(RFPROC|RFMEM|RFNOWAIT)){
case -1:
sysfatal("fork: %r");
case 0:
switch(kpid = rfork(RFPROC|RFNOTEG|RFENVG|RFFDG)){
case -1:
sysfatal("fork: %r");
case 0:
for(i=0; i<3; i++){
if(dup(pfd[i][1], i) < 0)
sysfatal("dup: %r");
close(pfd[i][0]);
close(pfd[i][1]);
}
putenv("user", c->user);
if(sysname)
putenv("sysname", sysname);
if(tz)
putenv("tz", tz);
dir = smprint("/usr/%s", c->user);
if(dir == nil || chdir(dir) < 0)
chdir("/");
if(cmd){
putenv("service", "rx");
execl("/bin/rc", "rc", "-lc", cmd, nil);
sysfatal("cannot exec /bin/rc: %r");
}else{
putenv("service", "con");
execl("/bin/ip/telnetd", "telnetd", "-tn", nil);
sysfatal("cannot exec /bin/ip/telnetd: %r");
}
default:
*kidpid = kpid;
rendezvous(kidpid, 0);
for(;;){
if((w = wait()) == nil)
sysfatal("wait: %r");
if(w->pid == kpid)
break;
free(w);
}
if(w->msg[0]){
m = allocmsg(c, SSH_MSG_DISCONNECT, 4+strlen(w->msg));
putstring(m, w->msg);
sendmsg(m);
}else{
m = allocmsg(c, SSH_SMSG_EXITSTATUS, 4);
putlong(m, 0);
sendmsg(m);
}
for(i=0; i<3; i++)
close(pfd[i][0]);
free(w);
exits(nil);
break;
}
default:
atexitkill(pid);
rendezvous(kidpid, 0);
break;
}
for(i=0; i<3; i++)
close(pfd[i][1]);
copyout(c, pfd[1][0], SSH_SMSG_STDOUT_DATA);
copyout(c, pfd[2][0], SSH_SMSG_STDERR_DATA);
*kidin = pfd[0][0];
}