#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;} voidusage(void){	fprint(2, "usage: sshserve [-A authlist] [-c cipherlist] client-ip-address\n");	exits("usage");} voidmain(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);} voidfromnet(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;		}	}} voidcopyout(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);} voidstartcmd(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];}