Use detection rather than python version checking.

Try importing from the newest location/name and then fallback if that
fails instead of using python version switches.

Still use version switch for the buffer/bytes to string wrapper
routines since python 2.6 has intermediate support for buffer/bytes
and I want to know if full support (ala python 3.0) is there.

websocket.py

@@ -17,60 +17,54 @@ as taken from http://docs.python.org/dev/library/ssl.html#certificates
 '''
 
 import os, sys, time, errno, signal, socket, traceback, select
-import array
+import array, struct
 from cgi import parse_qsl
 from base64 import b64encode, b64decode
 
 # Imports that vary by python version
+
+# python 3.0 differences
 if sys.hexversion > 0x3000000:
-    # python >= 3.0
-    from io import StringIO
-    from http.server import SimpleHTTPRequestHandler
-    from urllib.parse import urlsplit
     b2s = lambda buf: buf.decode('latin_1')
     s2b = lambda s: s.encode('latin_1')
     s2a = lambda s: s
 else:
-    # python 2.X
+    b2s = lambda buf: buf  # No-op
-    from cStringIO import StringIO
+    s2b = lambda s: s      # No-op
-    from SimpleHTTPServer import SimpleHTTPRequestHandler
-    from urlparse import urlsplit
-    # No-ops
-    b2s = lambda buf: buf
-    s2b = lambda s: s
     s2a = lambda s: [ord(c) for c in s]
+try:    from io import StringIO
+except: from cStringIO import StringIO
+try:    from http.server import SimpleHTTPRequestHandler
+except: from SimpleHTTPServer import SimpleHTTPRequestHandler
+try:    from urllib.parse import urlsplit
+except: from urlparse import urlsplit
 
-if sys.hexversion >= 0x2060000:
+# python 2.6 differences
-    # python >= 2.6
+try:    from hashlib import md5, sha1
-    from multiprocessing import Process
+except: from md5 import md5; from sha import sha as sha1
-    from hashlib import md5, sha1
-else:
-    # python < 2.6
-    Process = None
-    from md5 import md5
-    from sha import sha as sha1
 
-if sys.hexversion >= 0x2050000:
+# python 2.5 differences
-    # python >= 2.5
+try:
-    import struct
+    from struct import pack, unpack_from
-else:
+except:
-    # python < 2.5
+    from struct import pack
-    import struct
+    def unpack_from(fmt, buf, offset=0):
-    # unpack_from was introduced in python 2.5
-    def _unpack_from(fmt, buf, offset=0):
         slice = buffer(buf, offset, struct.calcsize(fmt))
         return struct.unpack(fmt, slice)
-    struct.unpack_from = _unpack_from
 
 # Degraded functionality if these imports are missing
-for mod, sup in [('numpy', 'HyBi protocol'),
+for mod, sup in [('numpy', 'HyBi protocol'), ('ssl', 'TLS/SSL/wss'),
-        ('ssl', 'TLS/SSL/wss'), ('resource', 'daemonizing')]:
+        ('multiprocessing', 'Multi-Processing'),
+        ('resource', 'daemonizing')]:
     try:
         globals()[mod] = __import__(mod)
     except ImportError:
         globals()[mod] = None
-        print("WARNING: no '%s' module, %s decode may be slower" % (
+        print("WARNING: no '%s' module, %s is slower or disabled" % (
             mod, sup))
+if multiprocessing and sys.platform == 'win32':
+    # make sockets pickle-able/inheritable
+    import multiprocessing.reduction
 
 
 class WebSocketServer(object):
@@ -277,11 +271,11 @@ Sec-WebSocket-Accept: %s\r
         b1 = 0x80 | (opcode & 0x0f) # FIN + opcode
         payload_len = len(buf)
         if payload_len <= 125:
-            header = struct.pack('>BB', b1, payload_len)
+            header = pack('>BB', b1, payload_len)
         elif payload_len > 125 and payload_len < 65536:
-            header = struct.pack('>BBH', b1, 126, payload_len)
+            header = pack('>BBH', b1, 126, payload_len)
         elif payload_len >= 65536:
-            header = struct.pack('>BBQ', b1, 127, payload_len)
+            header = pack('>BBQ', b1, 127, payload_len)
 
         #print("Encoded: %s" % repr(header + buf))
 
@@ -318,7 +312,7 @@ Sec-WebSocket-Accept: %s\r
         if blen < f['hlen']:
             return f # Incomplete frame header
 
-        b1, b2 = struct.unpack_from(">BB", buf)
+        b1, b2 = unpack_from(">BB", buf)
         f['opcode'] = b1 & 0x0f
         f['fin'] = (b1 & 0x80) >> 7
         has_mask = (b2 & 0x80) >> 7
@@ -329,12 +323,12 @@ Sec-WebSocket-Accept: %s\r
             f['hlen'] = 4
             if blen < f['hlen']:
                 return f # Incomplete frame header
-            (f['length'],) = struct.unpack_from('>xxH', buf)
+            (f['length'],) = unpack_from('>xxH', buf)
         elif f['length'] == 127:
             f['hlen'] = 10
             if blen < f['hlen']:
                 return f # Incomplete frame header
-            (f['length'],) = struct.unpack_from('>xxQ', buf)
+            (f['length'],) = unpack_from('>xxQ', buf)
 
         full_len = f['hlen'] + has_mask * 4 + f['length']
 
@@ -363,7 +357,7 @@ Sec-WebSocket-Accept: %s\r
 
         if f['opcode'] == 0x08:
             if f['length'] >= 2:
-                f['close_code'] = struct.unpack_from(">H", f['payload'])
+                f['close_code'] = unpack_from(">H", f['payload'])
             if f['length'] > 3:
                 f['close_reason'] = f['payload'][2:]
 
@@ -393,7 +387,7 @@ Sec-WebSocket-Accept: %s\r
         num1 = int("".join([c for c in key1 if c.isdigit()])) / spaces1
         num2 = int("".join([c for c in key2 if c.isdigit()])) / spaces2
 
-        return b2s(md5(struct.pack('>II8s',
+        return b2s(md5(pack('>II8s',
             int(num1), int(num2), key3)).digest())
 
     #
@@ -544,7 +538,7 @@ Sec-WebSocket-Accept: %s\r
         if self.version.startswith("hybi"):
             msg = s2b('')
             if code != None:
-                msg = struct.pack(">H%ds" % (len(reason)), code)
+                msg = pack(">H%ds" % (len(reason)), code)
 
             buf, h, t = self.encode_hybi(msg, opcode=0x08, base64=False)
             self.client.send(buf)
@@ -803,7 +797,7 @@ Sec-WebSocket-Accept: %s\r
 
         # Allow override of SIGINT
         signal.signal(signal.SIGINT, self.do_SIGINT)
-        if not Process:
+        if not multiprocessing:
             # os.fork() (python 2.4) child reaper
             signal.signal(signal.SIGCHLD, self.fallback_SIGCHLD)
 
@@ -849,9 +843,10 @@ Sec-WebSocket-Accept: %s\r
                             self.msg('%s: exiting due to --run-once'
                                     % address[0])
                             break
-                    elif Process:
+                    elif multiprocessing:
                         self.vmsg('%s: new handler Process' % address[0])
-                        p = Process(target=self.top_new_client,
+                        p = multiprocessing.Process(
+                                target=self.top_new_client,
                                 args=(startsock, address))
                         p.start()
                         # child will not return