Support unix domain sockets in nc(1) with -Uu.

Previously, using -U with -u was an error that was not documented
in the man page.  Now it will use a unix socket in datagram mode.

Bidirectional unix datagram communication requires a socket at
both ends, so in client mode (without -l), a temporary socket is
created so that responses from the server can be received.
If -s is specified with -U and -u, it specifies the location of
the temporary socket to create.

This was mostly written way back in 2007.  Since then, various
improvements implemented based on suggestions from guenther@,
tedu@, and nicm@. Man page help from nicm@ and jmc@.

Unix datagram support requires a small change to atomicio.c
in order to function correctly, this will be committed separately
shortly.

OK nicm@

2 files changed, 83 insertions, 25 deletions

diff --git a/src/usr.bin/nc/nc.1 b/src/usr.bin/nc/nc.1
index c2599ce3f1..8745528040 100644
--- a/src/usr.bin/nc/nc.1
+++ b/src/usr.bin/nc/nc.1
@@ -1,4 +1,4 @@
-.\"     $OpenBSD: nc.1,v 1.55 2010/07/25 07:51:39 guenther Exp $
+.\"     $OpenBSD: nc.1,v 1.56 2011/01/08 00:44:19 jeremy Exp $
 .\"
 .\" Copyright (c) 1996 David Sacerdote
 .\" All rights reserved.
@@ -25,7 +25,7 @@
 .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 .\"
-.Dd $Mdocdate: July 25 2010 $
+.Dd $Mdocdate: January 8 2011 $
 .Dt NC 1
 .Os
 .Sh NAME
@@ -155,6 +155,10 @@ assigns them.
 Enables the RFC 2385 TCP MD5 signature option.
 .It Fl s Ar source_ip_address
 Specifies the IP of the interface which is used to send the packets.
+For
+.Ux Ns -domain
+datagram sockets, specifies the local temporary socket file
+to create and use so that datagrams can be received.
 It is an error to use this option in conjunction with the
 .Fl l
 option.
@@ -179,6 +183,16 @@ Specifies to use
 sockets.
 .It Fl u
 Use UDP instead of the default option of TCP.
+For
+.Ux Ns -domain
+sockets, use a datagram socket instead of a stream socket.
+If a
+.Ux Ns -domain
+socket is used, a temporary receiving socket is created in
+.Pa /tmp
+unless the
+.Fl s
+flag is given.
 .It Fl V Ar rtable
 Set the routing table to be used.
 The default is 0.
diff --git a/src/usr.bin/nc/netcat.c b/src/usr.bin/nc/netcat.c
index e471182b2a..7b9fe41ba4 100644
--- a/src/usr.bin/nc/netcat.c
+++ b/src/usr.bin/nc/netcat.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: netcat.c,v 1.98 2010/07/03 04:44:51 guenther Exp $ */
+/* $OpenBSD: netcat.c,v 1.99 2011/01/08 00:44:19 jeremy Exp $ */
 /*
  * Copyright (c) 2001 Eric Jackson <ericj@monkey.org>
  *
@@ -62,6 +62,7 @@
 
 #define PORT_MAX        65535
 #define PORT_MAX_LEN    6
+#define UNIX_DG_TMP_SOCKET_SIZE 19
 
 /* Command Line Options */
 int     dflag;                                  /* detached, no stdin */
@@ -89,6 +90,7 @@ u_int	rtableid;
 int timeout = -1;
 int family = AF_UNSPEC;
 char *portlist[PORT_MAX+1];
+char *unix_dg_tmp_socket;
 
 void    atelnet(int, unsigned char *, unsigned int);
 void    build_ports(char *);
@@ -99,6 +101,7 @@ int	remote_connect(const char *, const char *, struct addrinfo);
 int     socks_connect(const char *, const char *, struct addrinfo,
             const char *, const char *, struct addrinfo, int, const char *);
 int     udptest(int);
+int     unix_bind(char *);
 int     unix_connect(char *);
 int     unix_listen(char *);
 void    set_common_sockopts(int);
@@ -117,6 +120,7 @@ main(int argc, char *argv[])
         char *proxy;
         const char *errstr, *proxyhost = "", *proxyport = NULL;
         struct addrinfo proxyhints;
+        char unix_dg_tmp_socket_buf[UNIX_DG_TMP_SOCKET_SIZE];
 
         ret = 1;
         s = 0;
@@ -241,8 +245,6 @@ main(int argc, char *argv[])
 
         /* Cruft to make sure options are clean, and used properly. */
         if (argv[0] && !argv[1] && family == AF_UNIX) {
-                if (uflag)
-                        errx(1, "cannot use -u and -U");
                 host = argv[0];
                 uport = NULL;
         } else if (argv[0] && !argv[1]) {
@@ -265,6 +267,19 @@ main(int argc, char *argv[])
         if (!lflag && kflag)
                 errx(1, "must use -l with -k");
 
+        /* Get name of temporary socket for unix datagram client */
+        if ((family == AF_UNIX) && uflag && !lflag) {
+                if (sflag) {
+                        unix_dg_tmp_socket = sflag;
+                } else {
+                        strlcpy(unix_dg_tmp_socket_buf, "/tmp/nc.XXXXXXXXXX",
+                                UNIX_DG_TMP_SOCKET_SIZE);
+                        if (mktemp(unix_dg_tmp_socket_buf) == NULL)
+                                err(1, "mktemp");
+                        unix_dg_tmp_socket = unix_dg_tmp_socket_buf;
+                }
+        }
+
         /* Initialize addrinfo structure. */
         if (family != AF_UNIX) {
                 memset(&hints, 0, sizeof(struct addrinfo));
@@ -307,8 +322,12 @@ main(int argc, char *argv[])
                 int connfd;
                 ret = 0;
 
-                if (family == AF_UNIX)
-                        s = unix_listen(host);
+                if (family == AF_UNIX) {
+                        if (uflag)
+                                s = unix_bind(host);
+                        else
+                                s = unix_listen(host);
+                }
 
                 /* Allow only one connection at a time, but stay alive. */
                 for (;;) {
@@ -337,17 +356,21 @@ main(int argc, char *argv[])
                                 if (rv < 0)
                                         err(1, "connect");
 
-                                connfd = s;
+                                readwrite(s);
                         } else {
                                 len = sizeof(cliaddr);
                                 connfd = accept(s, (struct sockaddr *)&cliaddr,
                                     &len);
+                                readwrite(connfd);
+                                close(connfd);
                         }
 
-                        readwrite(connfd);
-                        close(connfd);
                         if (family != AF_UNIX)
                                 close(s);
+                        else if (uflag) {
+                                if (connect(s, NULL, 0) < 0)
+                                        err(1, "connect");
+                        }
 
                         if (!kflag)
                                 break;
@@ -361,6 +384,8 @@ main(int argc, char *argv[])
                 } else
                         ret = 1;
 
+                if (uflag)
+                        unlink(unix_dg_tmp_socket);
                 exit(ret);
 
         } else {
@@ -421,18 +446,19 @@ main(int argc, char *argv[])
 }
 
 /*
- * unix_connect()
- * Returns a socket connected to a local unix socket. Returns -1 on failure.
+ * unix_bind()
+ * Returns a unix socket bound to the given path
  */
 int
-unix_connect(char *path)
+unix_bind(char *path)
 {
         struct sockaddr_un sun;
         int s;
 
-        if ((s = socket(AF_UNIX, SOCK_STREAM, 0)) < 0)
+        /* Create unix domain socket. */
+        if ((s = socket(AF_UNIX, uflag ? SOCK_DGRAM : SOCK_STREAM,
+             0)) < 0)
                 return (-1);
-        (void)fcntl(s, F_SETFD, 1);
 
         memset(&sun, 0, sizeof(struct sockaddr_un));
         sun.sun_family = AF_UNIX;
@@ -443,27 +469,32 @@ unix_connect(char *path)
                 errno = ENAMETOOLONG;
                 return (-1);
         }
-        if (connect(s, (struct sockaddr *)&sun, SUN_LEN(&sun)) < 0) {
+
+        if (bind(s, (struct sockaddr *)&sun, SUN_LEN(&sun)) < 0) {
                 close(s);
                 return (-1);
         }
         return (s);
-
 }
 
 /*
- * unix_listen()
- * Create a unix domain socket, and listen on it.
+ * unix_connect()
+ * Returns a socket connected to a local unix socket. Returns -1 on failure.
  */
 int
-unix_listen(char *path)
+unix_connect(char *path)
 {
         struct sockaddr_un sun;
         int s;
 
-        /* Create unix domain socket. */
-        if ((s = socket(AF_UNIX, SOCK_STREAM, 0)) < 0)
-                return (-1);
+        if (uflag) {
+                if ((s = unix_bind(unix_dg_tmp_socket)) < 0)
+                        return (-1);
+        } else {
+                if ((s = socket(AF_UNIX, SOCK_STREAM, 0)) < 0)
+                        return (-1);
+        }
+        (void)fcntl(s, F_SETFD, 1);
 
         memset(&sun, 0, sizeof(struct sockaddr_un));
         sun.sun_family = AF_UNIX;
@@ -474,11 +505,24 @@ unix_listen(char *path)
                 errno = ENAMETOOLONG;
                 return (-1);
         }
-
-        if (bind(s, (struct sockaddr *)&sun, SUN_LEN(&sun)) < 0) {
+        if (connect(s, (struct sockaddr *)&sun, SUN_LEN(&sun)) < 0) {
                 close(s);
                 return (-1);
         }
+        return (s);
+
+}
+
+/*
+ * unix_listen()
+ * Create a unix domain socket, and listen on it.
+ */
+int
+unix_listen(char *path)
+{
+        int s;
+        if ((s = unix_bind(path)) < 0)
+                return (-1);
 
         if (listen(s, 5) < 0) {
                 close(s);