diff -r 84c8127453cf Lib/test/test_socket.py
--- a/Lib/test/test_socket.py	Sat Oct 06 03:40:10 2012 +0200
+++ b/Lib/test/test_socket.py	Sat Oct 13 10:56:09 2012 +0200
@@ -726,6 +726,30 @@
         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_gethostbyname(self):
+        hostnames =  {
+                '0.0.0.0' : '0.0.0.0',
+                '127.0.0.1' : '127.0.0.1',
+                ' 10.0.0.1' : None,
+                '0.1.1.1.' : None,
+                '4294967306.4294967296.4294967296.1' : None,
+                'a1.1.1.1' : None,
+                '10.1a.1.1' : None,
+                '10.0.0.1ù' : None,
+                'thebestipevah' : None,
+        }
+
+        for host, expected_host in hostnames.items():
+            try:
+                hostbyname = socket.gethostbyname(host)
+            except socket.error:
+                if expected_host:
+                    self.fail('Failed to parse {}. Expected: {}'.format(
+                              repr(host), repr(expected_host)))
+            else:
+                self.assertEqual(hostbyname, expected_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 84c8127453cf Modules/socketmodule.c
--- a/Modules/socketmodule.c	Sat Oct 06 03:40:10 2012 +0200
+++ b/Modules/socketmodule.c	Sat Oct 13 10:56:09 2012 +0200
@@ -799,8 +799,10 @@
 {
     struct addrinfo hints, *res;
     int error;
-    int d1, d2, d3, d4;
-    char ch;
+    uint32_t ip;
+    long value;
+    size_t i;
+    char *str, *strend;
 
     memset((void *) addr_ret, '\0', sizeof(*addr_ret));
     if (name[0] == '\0') {
@@ -865,20 +867,37 @@
         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;
+    /* attempt to parse an ip address if of the form %d.%d.%d.%d */
+    str = name;
+    errno = 0;
+    value = ip = 0;
+    if (!isdigit(*str))
+        goto not_ip;
+    for (i = 3; i >= 0; i--) {
+        value = strtol(str, &strend, 10);
+        if (errno != 0 || value < 0 || value > 255) {
+            errno = 0;
+            goto not_ip;
+        }
+        ip |= value << (8 * i);
+        if (*strend == '.')
+            str = strend + 1;
+        else
+            break;
+
+    }
+    if (i > 0 || *strend != '\0')
+        goto not_ip;
+    struct sockaddr_in *sin;
+    sin = (struct sockaddr_in *)addr_ret;
+    sin->sin_addr.s_addr = htonl(ip);
+    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;
+
+not_ip:
     memset(&hints, 0, sizeof(hints));
     hints.ai_family = af;
     Py_BEGIN_ALLOW_THREADS
@@ -1641,7 +1660,7 @@
             return 0;
         }
 #endif
-            
+
 #ifdef PF_SYSTEM
     case PF_SYSTEM:
         switch (s->sock_proto) {
@@ -1649,10 +1668,10 @@
         case SYSPROTO_CONTROL:
         {
             struct sockaddr_ctl *addr;
-            
+
             addr = (struct sockaddr_ctl *)addr_ret;
             addr->sc_family = AF_SYSTEM;
-            addr->ss_sysaddr = AF_SYS_CONTROL; 
+            addr->ss_sysaddr = AF_SYS_CONTROL;
 
             if (PyUnicode_Check(args)) {
                 struct ctl_info info;
@@ -1678,17 +1697,17 @@
                           "cannot find kernel control with provided name");
                     return 0;
                 }
-                
+
                 addr->sc_id = info.ctl_id;
                 addr->sc_unit = 0;
             } else if (!PyArg_ParseTuple(args, "II",
                                          &(addr->sc_id), &(addr->sc_unit))) {
                 PyErr_SetString(PyExc_TypeError, "getsockaddrarg: "
                                 "expected str or tuple of two ints");
-                
+
                 return 0;
             }
-              
+
             *len_ret = sizeof(*addr);
             return 1;
         }
@@ -1805,7 +1824,7 @@
         return 1;
     }
 #endif
-            
+
 #ifdef PF_SYSTEM
     case PF_SYSTEM:
         switch(s->sock_proto) {