diff -r 4b3238923b01 Lib/test/test_socket.py
--- a/Lib/test/test_socket.py	Fri May 10 19:57:44 2013 -0700
+++ b/Lib/test/test_socket.py	Thu Aug 29 17:29:45 2013 +0200
@@ -761,6 +761,31 @@
         if not fqhn in all_host_names:
             self.fail("Error testing host resolution mechanisms. (fqdn: %s, all: %s)" % (fqhn, repr(all_host_names)))
 
+    def test_hosts_resolution(self):
+        valid_hosts = [support.HOST]
+        valid_hosts_ipv6 = [support.HOSTv6]
+
+        invalid_hosts = ['0.1.1.1.', 'a1.1.1.1', '10.1a.1.1',
+                         '4294967306.4294967296.4294967296.1']
+        invalid_hosts_ipv6 = ['::1q', '::1::2', '1:1:1:1:1:1:1:1:1']
+
+        for host in valid_hosts:
+            self.assertEqual(socket.gethostbyname(host), host)
+
+        for host in invalid_hosts:
+            self.assertRaises(OSError, socket.gethostbyname, host)
+
+        # gethostbyaddr() support IPv6, contrarily to gethosbyname()
+        if support.IPV6_ENABLED:
+            valid_hosts.extend(valid_hosts_ipv6)
+            invalid_hosts.extend(invalid_hosts_ipv6)
+
+        for host in valid_hosts:
+            self.assertIn(host, socket.gethostbyaddr(host)[2])
+
+        for host in invalid_hosts:
+            self.assertRaises(OSError, socket.gethostbyaddr, host)
+
     @unittest.skipUnless(hasattr(socket, 'sethostname'), "test needs socket.sethostname()")
     @unittest.skipUnless(hasattr(socket, 'gethostname'), "test needs socket.gethostname()")
     def test_sethostname(self):
diff -r 4b3238923b01 Modules/socketmodule.c
--- a/Modules/socketmodule.c	Fri May 10 19:57:44 2013 -0700
+++ b/Modules/socketmodule.c	Thu Aug 29 17:29:45 2013 +0200
@@ -442,6 +442,10 @@
 #define INVALID_SOCKET (-1)
 #endif
 
+#ifndef INADDR_NONE
+#define INADDR_NONE (-1)
+#endif
+
 /* XXX There's a problem here: *static* functions are not supposed to have
    a Py prefix (or use CapitalizedWords).  Later... */
 
@@ -799,8 +803,6 @@
 {
     struct addrinfo hints, *res;
     int error;
-    int d1, d2, d3, d4;
-    char ch;
 
     memset((void *) addr_ret, '\0', sizeof(*addr_ret));
     if (name[0] == '\0') {
@@ -849,7 +851,10 @@
         freeaddrinfo(res);
         return siz;
     }
-    if (name[0] == '<' && strcmp(name, "<broadcast>") == 0) {
+    /* special-case broadcast - inet_addr() below can return INADDR_NONE for
+     * this */ 
+    if (strcmp(name, "<broadcast>") == 0 ||
+        strcmp(name, "255.255.255.255") == 0) {
         struct sockaddr_in *sin;
         if (af != AF_INET && af != AF_UNSPEC) {
             PyErr_SetString(PyExc_OSError,
@@ -865,20 +870,52 @@
         sin->sin_addr.s_addr = INADDR_BROADCAST;
         return sizeof(sin->sin_addr);
     }
-    if (sscanf(name, "%d.%d.%d.%d%c", &d1, &d2, &d3, &d4, &ch) == 4 &&
-        0 <= d1 && d1 <= 255 && 0 <= d2 && d2 <= 255 &&
-        0 <= d3 && d3 <= 255 && 0 <= d4 && d4 <= 255) {
-        struct sockaddr_in *sin;
-        sin = (struct sockaddr_in *)addr_ret;
-        sin->sin_addr.s_addr = htonl(
-            ((long) d1 << 24) | ((long) d2 << 16) |
-            ((long) d3 << 8) | ((long) d4 << 0));
-        sin->sin_family = AF_INET;
+
+    /* avoid a name resolution in case of numeric address */
+#ifdef HAVE_INET_PTON
+    /* check for an IPv4 address */
+    if (af == AF_UNSPEC || af == AF_INET) {
+        struct sockaddr_in *sin = (struct sockaddr_in *)addr_ret;
+        if (inet_pton(AF_INET, name, &sin->sin_addr) > 0) {
+            sin->sin_family = AF_INET;
 #ifdef HAVE_SOCKADDR_SA_LEN
-        sin->sin_len = sizeof(*sin);
-#endif
-        return 4;
-    }
+            sin->sin_len = sizeof(*sin);
+#endif
+            return 4;
+        }
+    }
+#ifdef ENABLE_IPV6
+    /* check for an IPv6 address - if the address contains a scope ID, we
+     * fallback to getaddrinfo(), which can handle translation from interface
+     * name to interface index */
+    if ((af == AF_UNSPEC || af == AF_INET6) && !strchr(name, '%')) {
+        struct sockaddr_in6 *sin = (struct sockaddr_in6 *)addr_ret;
+        if (inet_pton(AF_INET6, name, &sin->sin6_addr) > 0) {
+            sin->sin6_family = AF_INET6;
+#ifdef HAVE_SOCKADDR_SA_LEN
+            sin->sin6_len = sizeof(*sin);
+#endif
+            return 16;
+        }
+    }
+#endif /* ENABLE_IPV6 */
+#else /* HAVE_INET_PTON */
+    /* check for an IPv4 address */
+     if (af == AF_INET || af == AF_UNSPEC) {
+        struct sockaddr_in *sin = (struct sockaddr_in *)addr_ret;
+        in_addr_t inaddr;
+        if ((inaddr = inet_addr(name)) != INADDR_NONE) {
+            sin->sin_addr.s_addr = inaddr;
+            sin->sin_family = AF_INET;
+#ifdef HAVE_SOCKADDR_SA_LEN
+            sin->sin_len = sizeof(*sin);
+#endif
+            return 4;
+        }
+    }   
+#endif /* HAVE_INET_PTON */
+
+    /* perform a name resolution */
     memset(&hints, 0, sizeof(hints));
     hints.ai_family = af;
     Py_BEGIN_ALLOW_THREADS
@@ -4711,9 +4748,6 @@
 static PyObject*
 socket_inet_aton(PyObject *self, PyObject *args)
 {
-#ifndef INADDR_NONE
-#define INADDR_NONE (-1)
-#endif
 #ifdef HAVE_INET_ATON
     struct in_addr buf;
 #endif
@@ -4755,7 +4789,7 @@
     /* special-case this address as inet_addr might return INADDR_NONE
      * for this */
     if (strcmp(ip_addr, "255.255.255.255") == 0) {
-        packed_addr = 0xFFFFFFFF;
+        packed_addr = INADDR_BROADCAST;
     } else {
 
         packed_addr = inet_addr(ip_addr);