#include "ssh.h" static voidsend_ssh_smsg_public_key(Conn *c){	int i;	Msg *m; 	m = allocmsg(c, SSH_SMSG_PUBLIC_KEY, 2048);	putbytes(m, c->cookie, COOKIELEN);	putRSApub(m, c->serverkey);	putRSApub(m, c->hostkey);	putlong(m, c->flags); 	for(i=0; i<c->nokcipher; i++)		c->ciphermask |= 1<<c->okcipher[i]->id;	putlong(m, c->ciphermask);	for(i=0; i<c->nokauthsrv; i++)		c->authmask |= 1<<c->okauthsrv[i]->id;	putlong(m, c->authmask); 	sendmsg(m);} static voidrecv_ssh_cmsg_session_key(Conn *c){	int i, id, n, serverkeylen, hostkeylen;	mpint *a, *b;	uchar *buf;	Msg *m;	RSApriv *ksmall, *kbig; 	m = recvmsg(c, SSH_CMSG_SESSION_KEY);	id = getbyte(m);	c->cipher = nil;	for(i=0; i<c->nokcipher; i++)		if(c->okcipher[i]->id == id)			c->cipher = c->okcipher[i];	if(c->cipher == nil)		sysfatal("invalid cipher selected"); 	if(memcmp(getbytes(m, COOKIELEN), c->cookie, COOKIELEN) != 0)		sysfatal("bad cookie"); 	serverkeylen = mpsignif(c->serverkey->n);	hostkeylen = mpsignif(c->hostkey->n);	ksmall = kbig = nil;	if(serverkeylen+128 <= hostkeylen){		ksmall = c->serverpriv;		kbig = c->hostpriv;	}else if(hostkeylen+128 <= serverkeylen){		ksmall = c->hostpriv;		kbig = c->serverpriv;	}else		sysfatal("server session and host keys do not differ by at least 128 bits"); 	b = getmpint(m); 	debug(DBG_CRYPTO, "encrypted with kbig is %B\n", b);	a = rsadecrypt(kbig, b, nil);	mpfree(b);	b = a;	a = rsaunpad(b);	mpfree(b);	b = a; 	debug(DBG_CRYPTO, "encrypted with ksmall is %B\n", b);	a = rsadecrypt(ksmall, b, nil);	mpfree(b);	b = a;	a = rsaunpad(b);	mpfree(b);	b = a; 	debug(DBG_CRYPTO, "munged is %B\n", b); 	n = (mpsignif(b)+7)/8;	if(n > SESSKEYLEN)		sysfatal("client sent short session key"); 	buf = emalloc(SESSKEYLEN);	mptoberjust(b, buf, SESSKEYLEN);	mpfree(b); 	for(i=0; i<SESSIDLEN; i++)		buf[i] ^= c->sessid[i]; 	memmove(c->sesskey, buf, SESSKEYLEN); 	debug(DBG_CRYPTO, "unmunged is %.*H\n", SESSKEYLEN, buf); 	c->flags = getlong(m);	free(m);} static AuthInfo*responselogin(char *user, char *resp){	Chalstate *c;	AuthInfo *ai; 	if((c = auth_challenge("proto=p9cr user=%q role=server", user)) == nil){		sshlog("auth_challenge failed for %s", user);		return nil;	}	c->resp = resp;	c->nresp = strlen(resp);	ai = auth_response(c);	auth_freechal(c);	return ai;} static AuthInfo*authusername(Conn *c){	char *p;	AuthInfo *ai; 	/*	 * hack for sam users: 'name numbers' gets tried as securid login.	 */	if(p = strchr(c->user, ' ')){		*p++ = '\0';		if((ai=responselogin(c->user, p)) != nil)			return ai;		*--p = ' ';		sshlog("bad response: %s", c->user);	}	return nil;} static voidauthsrvuser(Conn *c){	int i;	char *ns, *user;	AuthInfo *ai;	Msg *m; 	m = recvmsg(c, SSH_CMSG_USER);	user = getstring(m);	c->user = emalloc(strlen(user)+1);	strcpy(c->user, user);	free(m); 	ai = authusername(c);	while(ai == nil){		sendmsg(allocmsg(c, SSH_SMSG_FAILURE, 0));		m = recvmsg(c, 0);		if(m == nil)			badmsg(m, 0);		for(i=0; i<c->nokauthsrv; i++)			if(c->okauthsrv[i]->firstmsg == m->type){				ai = (*c->okauthsrv[i]->fn)(c, m);				break;			}		if(i==c->nokauthsrv)			badmsg(m, 0);	}	sendmsg(allocmsg(c, SSH_SMSG_SUCCESS, 0)); 	if(noworld(ai->cuid))		ns = "/lib/namespace.noworld";	else		ns = nil;	if(auth_chuid(ai, ns) < 0){		sshlog("auth_chuid to %s: %r", ai->cuid);		sysfatal("auth_chuid: %r");	}	sshlog("logged in as %s", ai->cuid);	auth_freeAI(ai);} voidsshserverhandshake(Conn *c){	char buf[128], *p;	int i; 	/* send id string */	fprint(c->fd[0], "SSH-1.5-Plan9\n"); 	/* receive id string */	if(readstrnl(c->fd[0], buf, sizeof buf) < 0)		sysfatal("reading server version: %r"); 	/* id string is "SSH-m.n-comment".  We need m=1, n>=5. */	if(strncmp(buf, "SSH-", 4) != 0	|| strtol(buf+4, &p, 10) != 1	|| *p != '.'	|| strtol(p+1, &p, 10) < 5	|| *p != '-')		sysfatal("protocol mismatch; got %s, need SSH-1.x for x>=5", buf); 	for(i=0; i<COOKIELEN; i++)		c->cookie[i] = fastrand();	calcsessid(c);	send_ssh_smsg_public_key(c);	recv_ssh_cmsg_session_key(c); 	c->cstate = (*c->cipher->init)(c, 1);		/* turns on encryption */	sendmsg(allocmsg(c, SSH_SMSG_SUCCESS, 0)); 	authsrvuser(c);}