- djm@cvs.openbsd.org 2009/02/12 03:00:56

     [canohost.c canohost.h channels.c channels.h clientloop.c readconf.c]
     [readconf.h serverloop.c ssh.c]
     support remote port forwarding with a zero listen port (-R0:...) to
     dyamically allocate a listen port at runtime (this is actually
     specified in rfc4254); bz#1003 ok markus@

1 files changed, 44 insertions, 8 deletions

diff --git a/channels.c b/channels.c
index 0b1c34c83..dea60ba24 100644
--- a/channels.c
+++ b/channels.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: channels.c,v 1.294 2009/01/22 09:49:57 djm Exp $ */
+/* $OpenBSD: channels.c,v 1.295 2009/02/12 03:00:56 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -2460,7 +2460,8 @@ channel_set_af(int af)
 }
 
 static int
-channel_setup_fwd_listener(int type, const char *listen_addr, u_short listen_port,
+channel_setup_fwd_listener(int type, const char *listen_addr,
+    u_short listen_port, int *allocated_listen_port,
     const char *host_to_connect, u_short port_to_connect, int gateway_ports)
 {
         Channel *c;
@@ -2468,6 +2469,7 @@ channel_setup_fwd_listener(int type, const char *listen_addr, u_short listen_por
         struct addrinfo hints, *ai, *aitop;
         const char *host, *addr;
         char ntop[NI_MAXHOST], strport[NI_MAXSERV];
+        in_port_t *lport_p;
 
         host = (type == SSH_CHANNEL_RPORT_LISTENER) ?
             listen_addr : host_to_connect;
@@ -2536,10 +2538,29 @@ channel_setup_fwd_listener(int type, const char *listen_addr, u_short listen_por
                 }
                 return 0;
         }
-
+        if (allocated_listen_port != NULL)
+                *allocated_listen_port = 0;
         for (ai = aitop; ai; ai = ai->ai_next) {
-                if (ai->ai_family != AF_INET && ai->ai_family != AF_INET6)
+                switch (ai->ai_family) {
+                case AF_INET:
+                        lport_p = &((struct sockaddr_in *)ai->ai_addr)->
+                            sin_port;
+                        break;
+                case AF_INET6:
+                        lport_p = &((struct sockaddr_in6 *)ai->ai_addr)->
+                            sin6_port;
+                        break;
+                default:
                         continue;
+                }
+                /*
+                 * If allocating a port for -R forwards, then use the
+                 * same port for all address families.
+                 */
+                if (type == SSH_CHANNEL_RPORT_LISTENER && listen_port == 0 &&
+                    allocated_listen_port != NULL && *allocated_listen_port > 0)
+                        *lport_p = htons(*allocated_listen_port);
+
                 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop, sizeof(ntop),
                     strport, sizeof(strport), NI_NUMERICHOST|NI_NUMERICSERV) != 0) {
                         error("channel_setup_fwd_listener: getnameinfo failed");
@@ -2555,7 +2576,8 @@ channel_setup_fwd_listener(int type, const char *listen_addr, u_short listen_por
 
                 channel_set_reuseaddr(sock);
 
-                debug("Local forwarding listening on %s port %s.", ntop, strport);
+                debug("Local forwarding listening on %s port %s.",
+                    ntop, strport);
 
                 /* Bind the socket to the address. */
                 if (bind(sock, ai->ai_addr, ai->ai_addrlen) < 0) {
@@ -2574,6 +2596,19 @@ channel_setup_fwd_listener(int type, const char *listen_addr, u_short listen_por
                         close(sock);
                         continue;
                 }
+
+                /*
+                 * listen_port == 0 requests a dynamically allocated port -
+                 * record what we got.
+                 */
+                if (type == SSH_CHANNEL_RPORT_LISTENER && listen_port == 0 &&
+                    allocated_listen_port != NULL &&
+                    *allocated_listen_port == 0) {
+                        *allocated_listen_port = get_sock_port(sock, 1);
+                        debug("Allocated listen port %d",
+                            *allocated_listen_port);
+                }
+
                 /* Allocate a channel number for the socket. */
                 c = channel_new("port listener", type, sock, sock, -1,
                     CHAN_TCP_WINDOW_DEFAULT, CHAN_TCP_PACKET_DEFAULT,
@@ -2616,17 +2651,18 @@ channel_setup_local_fwd_listener(const char *listen_host, u_short listen_port,
     const char *host_to_connect, u_short port_to_connect, int gateway_ports)
 {
         return channel_setup_fwd_listener(SSH_CHANNEL_PORT_LISTENER,
-            listen_host, listen_port, host_to_connect, port_to_connect,
+            listen_host, listen_port, NULL, host_to_connect, port_to_connect,
             gateway_ports);
 }
 
 /* protocol v2 remote port fwd, used by sshd */
 int
 channel_setup_remote_fwd_listener(const char *listen_address,
-    u_short listen_port, int gateway_ports)
+    u_short listen_port, int *allocated_listen_port, int gateway_ports)
 {
         return channel_setup_fwd_listener(SSH_CHANNEL_RPORT_LISTENER,
-            listen_address, listen_port, NULL, 0, gateway_ports);
+            listen_address, listen_port, allocated_listen_port,
+            NULL, 0, gateway_ports);
 }
 
 /*