Fix connect/sendto/sendmsg into making sure to ignore bytes beyond sockaddr length

diff --git a/hurd/hurdsocket.h b/hurd/hurdsocket.h
new file mode 100644
index 0000000..fd45f34
--- /dev/null
+++ b/hurd/hurdsocket.h
@@ -0,0 +1,22 @@ 
+/* Hurd-specific socket functions
+   Copyright (C) 2013-2015 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <string.h>
+
+#define _hurd_sun_path_dupa(__addr, __len) \
+  strndupa ((__addr)->sun_path, (__len) - offsetof (struct sockaddr_un, sun_path))
diff --git a/sysdeps/mach/hurd/bind.c b/sysdeps/mach/hurd/bind.c
index 1704e94..908b15c 100644
--- a/sysdeps/mach/hurd/bind.c
+++ b/sysdeps/mach/hurd/bind.c
@@ -25,7 +25,7 @@ 
 #include <stddef.h>
 #include <hurd/ifsock.h>
 #include <sys/un.h>
-#include <string.h>
+#include "hurd/hurdsocket.h"
 
 /* Give the socket FD the local address ADDR (which is LEN bytes long).  */
 int
@@ -37,13 +37,11 @@  __bind  (int fd, __CONST_SOCKADDR_ARG addrarg, socklen_t len)
 
   if (addr->sun_family == AF_LOCAL)
     {
+      char *name = _hurd_sun_path_dupa (addr, len);
       /* For the local domain, we must create a node in the filesystem
 	 using the ifsock translator and then fetch the address from it.  */
       file_t dir, node;
-      char name[len - offsetof (struct sockaddr_un, sun_path) + 1], *n;
-
-      strncpy (name, addr->sun_path, sizeof name - 1);
-      name[sizeof name - 1] = '\0'; /* Make sure */
+      char *n;
 
       dir = __file_name_split (name, &n);
       if (dir == MACH_PORT_NULL)
diff --git a/sysdeps/mach/hurd/connect.c b/sysdeps/mach/hurd/connect.c
index 60856ae..b974b06 100644
--- a/sysdeps/mach/hurd/connect.c
+++ b/sysdeps/mach/hurd/connect.c
@@ -22,6 +22,7 @@ 
 #include <hurd/socket.h>
 #include <sys/un.h>
 #include <hurd/ifsock.h>
+#include "hurd/hurdsocket.h"
 
 /* Open a connection on socket FD to peer at ADDR (which LEN bytes long).
    For connectionless socket types, just set the default address to send to
@@ -36,9 +37,10 @@  __connect (int fd, __CONST_SOCKADDR_ARG addrarg, socklen_t len)
 
   if (addr->sun_family == AF_LOCAL)
     {
+      char *name = _hurd_sun_path_dupa (addr, len);
       /* For the local domain, we must look up the name as a file and talk
 	 to it with the ifsock protocol.  */
-      file_t file = __file_name_lookup (addr->sun_path, 0, 0);
+      file_t file = __file_name_lookup (name, 0, 0);
       if (file == MACH_PORT_NULL)
 	return -1;
       err = __ifsock_getsockaddr (file, &aport);
diff --git a/sysdeps/mach/hurd/sendmsg.c b/sysdeps/mach/hurd/sendmsg.c
index 5a93c63..fee722c 100644
--- a/sysdeps/mach/hurd/sendmsg.c
+++ b/sysdeps/mach/hurd/sendmsg.c
@@ -24,6 +24,7 @@ 
 #include <hurd/fd.h>
 #include <hurd/ifsock.h>
 #include <hurd/socket.h>
+#include "hurd/hurdsocket.h"
 
 /* Send a message described MESSAGE on socket FD.
    Returns the number of bytes sent, or -1 for errors.  */
@@ -104,9 +105,10 @@  __libc_sendmsg (int fd, const struct msghdr *message, int flags)
     {
       if (addr->sun_family == AF_LOCAL)
 	{
+	  char *name = _hurd_sun_path_dupa (addr, addr_len);
 	  /* For the local domain, we must look up the name as a file
 	     and talk to it with the ifsock protocol.  */
-	  file_t file = __file_name_lookup (addr->sun_path, 0, 0);
+	  file_t file = __file_name_lookup (name, 0, 0);
 	  if (file == MACH_PORT_NULL)
 	    {
 	      if (dealloc)
diff --git a/sysdeps/mach/hurd/sendto.c b/sysdeps/mach/hurd/sendto.c
index 72c1d6b..1b5654b 100644
--- a/sysdeps/mach/hurd/sendto.c
+++ b/sysdeps/mach/hurd/sendto.c
@@ -22,6 +22,7 @@ 
 #include <hurd/fd.h>
 #include <hurd/ifsock.h>
 #include <hurd/socket.h>
+#include "hurd/hurdsocket.h"
 
 /* Send N bytes of BUF on socket FD to peer at address ADDR (which is
    ADDR_LEN bytes long).  Returns the number sent, or -1 for errors.  */
@@ -47,9 +48,10 @@  __sendto (int fd,
 
       if (addr->sun_family == AF_LOCAL)
 	{
+	  char *name = _hurd_sun_path_dupa (addr, addr_len);
 	  /* For the local domain, we must look up the name as a file and talk
 	     to it with the ifsock protocol.  */
-	  file_t file = __file_name_lookup (addr->sun_path, 0, 0);
+	  file_t file = __file_name_lookup (name, 0, 0);
 	  if (file == MACH_PORT_NULL)
 	    return errno;
 	  err_port = __ifsock_getsockaddr (file, aport);