From 9f3fa403ef0d7e42c158280c1821440d9c267a42 Mon Sep 17 00:00:00 2001
From: david <david@e0a8ed71-7df4-0310-8962-fdc924857419>
Date: Tue, 27 Nov 2012 21:47:26 +0000
Subject: [PATCH] Automatically create and delete a source Unix domain DGRAM
 socket.

Patch based on one by Tomas Hozza.
http://seclists.org/nmap-dev/2012/q4/334
---
 ncat/docs/ncat.xml     |  7 +++++--
 ncat/ncat_connect.c    | 21 +++++++++++++++++++--
 ncat/test/ncat-test.pl | 13 +++++++++++++
 3 files changed, 37 insertions(+), 4 deletions(-)

diff --git a/ncat/docs/ncat.xml b/ncat/docs/ncat.xml
index fd8cd8301..7ecb0d659 100644
--- a/ncat/docs/ncat.xml
+++ b/ncat/docs/ncat.xml
@@ -767,8 +767,11 @@
     Both stream and datagram domain sockets are supported. Use
     <option>-U</option> on its own for stream sockets, or
     combine it with <option>--udp</option> for datagram sockets.
-    Datagram sockets require the use of the <option>--source</option>
-    option to specify a source socket to connect from.
+    Datagram sockets require a source socket to connect from. By
+    default, a source socket with a random filename will be created as
+    needed, and deleted when the program ends. Use the
+    <option>--source</option> with a path to use a source socket with a
+    specific name.
     </para>
 
   </refsect1>
diff --git a/ncat/ncat_connect.c b/ncat/ncat_connect.c
index 82cbf8d1a..23cd3ede6 100644
--- a/ncat/ncat_connect.c
+++ b/ncat/ncat_connect.c
@@ -519,10 +519,19 @@ int ncat_connect(void)
         if (o.af == AF_UNIX && o.udp)
         {
             if (srcaddr.storage.ss_family != AF_UNIX) {
-		bye("A source socket filename (--source) is required when using\n"
-		    "Unix domain sockets in --udp mode.");
+                char *tmp_name = NULL;
+                /* If no source socket was specified, we have to create temporary one. */
+                if ((tmp_name = tempnam(NULL, "ncat.")) == NULL)
+                    bye("Failed to create name for temporary DGRAM source Unix domain socket (tempnam).");
+
+                srcaddr.un.sun_family = AF_UNIX;
+                strncpy(srcaddr.un.sun_path, tmp_name, sizeof(srcaddr.un.sun_path));
+                free (tmp_name);
             }
             nsi_set_localaddr(cs.sock_nsi, &srcaddr.storage, SUN_LEN((struct sockaddr_un *)&srcaddr.storage));
+
+            if (o.verbose)
+                loguser("[%s] used as source DGRAM Unix domain socket.\n", srcaddr.un.sun_path);
         }
         else
 #endif
@@ -675,6 +684,14 @@ int ncat_connect(void)
             nsi_get_read_count(cs.sock_nsi), time);
     }
 
+#if HAVE_SYS_UN_H
+    if (o.af == AF_UNIX && o.udp) {
+        if (o.verbose)
+            loguser("Deleting source DGRAM Unix domain socket. [%s]\n", srcaddr.un.sun_path);
+        unlink(srcaddr.un.sun_path);
+    }
+#endif
+
     nsp_delete(mypool);
 
     return rc == NSOCK_LOOP_ERROR ? 1 : 0;
diff --git a/ncat/test/ncat-test.pl b/ncat/test/ncat-test.pl
index 25f1e7481..26970417a 100755
--- a/ncat/test/ncat-test.pl
+++ b/ncat/test/ncat-test.pl
@@ -548,6 +548,19 @@ sub {
 kill_children;
 unlink($UNIXSOCK);
 
+($s_pid, $s_out, $s_in) = ncat("-l", "-U", "--udp", $UNIXSOCK);
+test "Server UNIX socket listen on $UNIXSOCK --udp (DGRAM)",
+sub {
+	my $resp;
+
+	unlink($UNIXSOCK);
+	my ($c_pid, $c_out, $c_in) = ncat("-U", "--udp", $UNIXSOCK);
+	syswrite($c_in, "abc\n");
+	$resp = timeout_read($s_out);
+	$resp eq "abc\n" or die "Server got \"$resp\", not \"abc\\n\" from client";
+};
+kill_children;
+unlink($UNIXSOCK);
 
 server_client_test "Connect success exit code",
 [], ["--send-only"], sub {