Implement basic parsing of SOCKS messages with parsley

* Does not parse authenticated messages
* XXX Currently parsing of reply messages and methods is broken because of
https://bugs.launchpad.net/parsley/+bug/1085492

txsocksx/parser.py

@@ -0,0 +1,82 @@
+import parsley
+import struct
+
+socks_grammar = """
+# XXX Is this correct?
+octet = anything
+
+byteToInt = octet:b
+    -> ord(b)
+
+byteToIntStr = octet:b
+    -> str(ord(b))
+
+ver = '\x05' | '\x04'
+
+rsv = '\x00'
+
+IPV4Addr = anything{4}:quads
+    -> '.'.join(str(ord(q)) for q in quads)
+
+IPV6Addr = <anything{16}>
+
+# XXX notes
+# letterOrDigitOrHyphen = letterOrDigit | '-'
+# domainLabel = <(letter letterOrDigitOrHyphen{0, 61} letterOrDigit)>
+# domainName =
+#    < (domainLabel '.'?)* >
+
+# XXX make this stricter
+SOCKSDomainName =
+    byteToInt:len <anything*>
+
+SOCKSAddress = (token('\x01') IPV4Addr:addr
+                    -> addr
+
+                | token('\x03') IPV6Addr:addr
+                    -> addr
+
+                | token('\x04') SOCKSDomainName:domain
+                    -> domain
+                )
+
+port = anything{2}
+
+# The Client version identified/method selection message
+clientVersionMethodMessage =
+    ver octet:nmethods octet{1, 255}:methods
+    -> (ver, nmethods, methods)
+
+methods = tokenize('\x00') -> 'No Authentication Required'
+          | tokenize('\x01') -> 'GSSAPI'
+          | tokenize('\x02') -> 'Username/Password'
+          | tokenize('\xFF') -> 'No Acceptable Methods'
+
+# The Server version identified/method selection message
+serverVersionMethodMessage =
+    ver methods -> (ver, method)
+
+cmd = token('\x01') -> 'Connect'
+      | token('\x02') -> 'Bind'
+      | token('\x03') -> 'UDP Associate'
+
+clientRequestMessage =
+    ver cmd rsv SOCKSAddress port
+
+rep = token('\x00') -> 'Suceeded'
+      | token('\x01') -> 'General SOCKS server failure'
+      | token('\x02') -> 'Connection not allowed'
+      | token('\x03') -> 'Network unreachable'
+      | token('\x04') -> 'Host unreachable'
+      | token('\x05') -> 'Connection refused'
+      | token('\x06') -> 'TTL expired'
+      | token('\x07') -> 'Command not supported'
+      | token('\x08') -> 'Address type not supported'
+
+serverReplyMessage =
+    ver rep:reply rsv SOCKSAddress:address port:port
+    -> (reply, address, port)
+"""
+
+SOCKSGrammar = parsley.makeGrammar(socks_grammar, {})
+

txsocksx/test/test_parser.py

@@ -0,0 +1,59 @@
+import struct
+import parsley
+
+from unittest import TestCase
+
+from txsocksx.parser import SOCKSGrammar
+
+# From https://gist.github.com/1595135
+def IPV4StrToInt(s):
+    """
+    Returns the 32 bits representing an IP address from a string.
+    """
+    return reduce(lambda a,b: a<<8 | b, map(int, s.split(".")))
+
+dummyDomain = 'example.com'
+dummyIPV4Addr = '127.0.0.1'
+dummyIPV4AddrBytes = struct.pack('!i', IPV4StrToInt(dummyIPV4Addr))
+
+dummyPort = 1080
+dummyPortBytes = struct.pack('l', dummyPort)
+
+dummyClientVersionMethodMessageNoAuthV5 = \
+    '\x05\x01\x00'
+
+dummyServerVersionMethodMessageNoAuthV5 = \
+    '\x05\x00'
+
+dummySOCKSAddrIPV4 = '\x01' + dummyIPV4AddrBytes
+dummySOCKSAddrDomain = '\x04' + '\x08' + dummyDomain
+
+dummyClientRequestMessageConnectDomainV5 = \
+        '\x05\x01\x00' + dummySOCKSAddrDomain
+
+dummyServerReplyMessageSuccessIPV4 = \
+        '\x05\x00\x00' + '\x03' + dummyIPV4AddrBytes + dummyPortBytes
+
+
+class TestSOCKSParser(TestCase):
+    def test_parse_socks_domain(self):
+        p = SOCKSGrammar(dummySOCKSAddrDomain)
+        self.assertEqual(p.SOCKSAddress(),
+                'example.com')
+
+    def test_parse_socks_ipv4(self):
+        p = SOCKSGrammar(dummySOCKSAddrIPV4)
+        self.assertEqual(p.SOCKSAddress(),
+                '127.0.0.1')
+
+    def test_parse_client_connect_request_message(self):
+        p = SOCKSGrammar(dummyClientRequestMessageConnectDomainV5)
+        self.assertEqual(p.clientRequestMessage(),
+                    ('Connect', dummyIPV4Addr, dummyPort))
+
+    def test_parse_client_request_message(self):
+        p = SOCKSGrammar(dummyServerReplyMessageSuccessIPV4)
+        self.assertEqual(p.clientRequestMessage(),
+                ('Success', dummyIPV4Addr, dummyPort))
+
+