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sshnet: implement listen (port forwarding)

--- a/sys/man/4/sshnet

+++ b/sys/man/4/sshnet

@@ -45,8 +45,6 @@

 as is.

 .SH SOURCE

 .B /sys/src/cmd/sshnet.c

-.SH BUGS

-Incoming connections are not supported.

 .SH "SEE ALSO"

 .IR ssh (1),

 .IR ip (3)

--- a/sys/src/cmd/sshnet.c

+++ b/sys/src/cmd/sshnet.c

@@ -26,6 +26,7 @@

 	Qlocal,

 	Qremote,

 	Qstatus,

+	Qlisten,

 };

 #define PATH(type, n)		((type)|((n)<<8))

@@ -44,6 +45,8 @@

 {

 	Closed,

 	Dialing,

+	Announced,

+	Listen,

 	Established,

 	Teardown,

 	Finished,

@@ -52,6 +55,8 @@

 char *statestr[] = {

 	"Closed",

 	"Dialing",

+	"Announced",

+	"Listen",

 	"Established",

 	"Teardown",

 	"Finished",

@@ -63,8 +68,11 @@

 	int state;

 	int num;

 	int servernum;

-	char *connect;

+	int rport, lport;

+	char *rhost;

+	char *lhost;

+

 	int sendpkt;

 	int sendwin;

 	int recvwin;

@@ -83,6 +91,8 @@

 };

 enum {

+	MSG_GLOBAL_REQUEST = 80,

+

 	MSG_CHANNEL_OPEN = 90,

 	MSG_CHANNEL_OPEN_CONFIRMATION,

 	MSG_CHANNEL_OPEN_FAILURE,

@@ -119,8 +129,6 @@

 Client **client;

 char *mtpt;

 int sshfd;

-int localport;

-char localip[] = "::";

 int

 vpack(uchar *p, int n, char *fmt, va_list a)

@@ -301,6 +309,19 @@

 	return client[num];

 }

+Client*

+getlistener(char *host, int port)

+{

+	int i;

+

+	USED(host);

+	for(i = 0; i < nclient; i++){

+		if(client[i]->state == Listen && client[i]->lport == port)

+			return client[i];

+	}

+	return nil;

+}

+

 void

 adjustwin(Client *c, int len)

 {

@@ -472,6 +493,16 @@

 		c->state = Closed;

 		sendmsg(pack(nil, "bu", MSG_CHANNEL_CLOSE, c->servernum));

 		break;

+	case Announced:

+		sendmsg(pack(nil, "bsbsu", MSG_GLOBAL_REQUEST,

+			"cancel-tcpip-forward", 20,

+			0,

+			c->lhost, strlen(c->lhost),

+			c->lport));

+		/* wet floor */

+	case Listen:

+		c->state = Closed;

+		break;

 	}

 	while((m = c->mq) != nil){

 		c->mq = m->link;

@@ -514,6 +545,7 @@

 	"local",	0444,

 	"remote",	0444,

 	"status",	0444,

+	"listen",	0666,

 };

 static void

@@ -768,7 +800,7 @@

 ctlwrite(Req *r, Client *c)

 {

 	char *f[3], *s;

-	int nf;

+	int nf, port;

 	s = emalloc9p(r->ifcall.count+1);

 	r->ofcall.count = r->ifcall.count;

@@ -790,15 +822,18 @@

 		teardownclient(c);

 		respond(r, nil);

 	}else if(strcmp(f[0], "connect") == 0){

-		if(c->state != Closed)

+		if(nf != 2 || c->state != Closed)

 			goto Badarg;

-		if(nf != 2)

+		if(getfields(f[1], f, nelem(f), 0, "!") != 2)

 			goto Badarg;

-		free(c->connect);

-		c->connect = estrdup9p(f[1]);

-		nf = getfields(f[1], f, nelem(f), 0, "!");

-		if(nf != 2)

+		if((port = ndbfindport(f[1])) < 0)

 			goto Badarg;

+		free(c->lhost);

+		c->lhost = estrdup9p("::");

+		c->lport = 0;

+		free(c->rhost);

+		c->rhost = estrdup9p(f[0]);

+		c->rport = port;

 		c->recvwin = WinPackets*MaxPacket;

 		c->recvacc = 0;

 		c->state = Dialing;

@@ -807,8 +842,28 @@

 		sendmsg(pack(nil, "bsuuususu", MSG_CHANNEL_OPEN,

 			"direct-tcpip", 12,

 			c->num, c->recvwin, MaxPacket,

-			f[0], strlen(f[0]), ndbfindport(f[1]),

-			localip, strlen(localip), localport));

+			c->rhost, strlen(c->rhost), c->rport,

+			c->lhost, strlen(c->lhost), c->lport));

+	}else if(strcmp(f[0], "announce") == 0){

+		if(nf != 2 || c->state != Closed)

+			goto Badarg;

+		if(getfields(f[1], f, nelem(f), 0, "!") != 2)

+			goto Badarg;

+		if((port = ndbfindport(f[1])) < 0)

+			goto Badarg;

+		if(strcmp(f[0], "*") == 0)

+			f[0] = "";

+		free(c->lhost);

+		c->lhost = estrdup9p(f[0]);

+		c->lport = port;

+		free(c->rhost);

+		c->rhost = estrdup9p("::");

+		c->rport = 0;

+		c->state = Announced;

+		sendmsg(pack(nil, "bsbsu", MSG_GLOBAL_REQUEST,

+			"tcpip-forward", 13, 0,

+			c->lhost, strlen(c->lhost), c->lport));

+		respond(r, nil);

 	}else{

 	Badarg:

 		respond(r, "bad or inappropriate tcp control message");

@@ -844,11 +899,16 @@

 }

 static void

-localread(Req *r)

+localread(Req *r, Client *c)

 {

-	char buf[128];

+	char buf[128], *s;

-	snprint(buf, sizeof buf, "%s!%d\n", localip, localport);

+	s = c->lhost;

+	if(s == nil)

+		s = "::";

+	else if(*s == 0)

+		s = "*";

+	snprint(buf, sizeof buf, "%s!%d\n", s, c->lport);

 	readstr(r, buf);

 	respond(r, nil);

 }

@@ -856,13 +916,12 @@

 static void

 remoteread(Req *r, Client *c)

 {

-	char *s;

-	char buf[128];

+	char buf[128], *s;

-	s = c->connect;

+	s = c->rhost;

 	if(s == nil)

-		s = "::!0";

-	snprint(buf, sizeof buf, "%s\n", s);

+		s = "::";

+	snprint(buf, sizeof buf, "%s!%d\n", s, c->rport);

 	readstr(r, buf);

 	respond(r, nil);

 }

@@ -918,7 +977,7 @@

 		break;

 	case Qlocal:

-		localread(r);

+		localread(r, client[NUM(path)]);

 		break;

 	case Qremote:

@@ -985,6 +1044,22 @@

 		r->fid->aux = cs;

 		respond(r, nil);

 		break;

+	case Qlisten:

+		if(client[NUM(path)]->state != Announced){

+			respond(r, "not announced");

+			break;

+		}

+		n = newclient();

+		free(client[n]->lhost);

+		client[n]->lhost = estrdup9p(client[NUM(path)]->lhost);

+		client[n]->lport = client[NUM(path)]->lport;

+		r->fid->qid.path = PATH(Qctl, n);

+		r->ofcall.qid.path = r->fid->qid.path;

+		r->aux = nil;

+		client[n]->wq = r;

+		client[n]->ref++;

+		client[n]->state = Listen;

+		break;

 	case Qclone:

 		n = newclient();

 		path = PATH(Qctl, n);

@@ -1016,9 +1091,9 @@

 static void

 handlemsg(Msg *m)

 {

-	int chan, win, pkt, n;

+	int chan, win, pkt, lport, rport, n, ln, rn;

+	char *s, *lhost, *rhost;

 	Client *c;

-	char *s;

 	switch(m->rp[0]){

 	case MSG_CHANNEL_WINDOW_ADJUST:

@@ -1108,6 +1183,50 @@

 			hangupclient(c, s);

 		}

 		free(s);

+		break;

+	case MSG_CHANNEL_OPEN:

+		if(unpack(m, "_suuususu", &s, &n, &chan,

+			&win, &pkt,

+			&lhost, &ln, &lport,

+			&rhost, &rn, &rport) < 0)

+			break;

+		if(n != 15 || strncmp(s, "forwarded-tcpip", 15) != 0){

+			n = 3, s = "unknown open type";

+		Reject:

+			sendmsg(pack(nil, "buus", MSG_CHANNEL_OPEN_FAILURE,

+				chan, n, s, strlen(s)));

+			break;

+		}

+		lhost = smprint("%.*s", utfnlen(lhost, ln), lhost);

+		rhost = smprint("%.*s", utfnlen(rhost, rn), rhost);

+		c = getlistener(lhost, lport);

+		if(c == nil){

+			free(lhost);

+			free(rhost);

+			n = 2, s = "connection refused";

+			goto Reject;

+		}

+		free(c->lhost);

+		c->lhost = lhost;

+		c->lport = lport;

+		free(c->rhost);

+		c->rhost = rhost;

+		c->rport = rport;

+		c->servernum = chan;

+		c->recvwin = WinPackets*MaxPacket;

+		c->recvacc = 0;

+		c->eof = 0;

+		c->sendpkt = pkt;

+		c->sendwin = win;

+		c->state = Established;

+		sendmsg(pack(nil, "buuuu", MSG_CHANNEL_OPEN_CONFIRMATION,

+			c->servernum, c->num, c->recvwin, MaxPacket));

+		if(c->wq == nil){

+			teardownclient(c);

+			break;

+		}

+		respond(c->wq, nil);

+		c->wq = nil;

 		break;

 	}

 	free(m);