Add simple python tool to use Tor for DNS lookups

svn:r1977

contrib/tor_resolve

@@ -0,0 +1,122 @@
+#!/usr/bin/python
+#$Id$
+
+import socket
+import struct
+import sys
+
+def socks4AResolveRequest(hostname):
+    version = 4
+    command = 0xF0
+    port = 0
+    addr = 0x0000001
+    username = ""
+    reqheader = struct.pack("!BBHL", version, command, port, addr)
+    return "%s%s\x00%s\x00"%(reqheader,username,hostname)
+
+def socks4AParseResponse(response):
+    RESPONSE_LEN = 8
+    if len(response) < RESPONSE_LEN:
+        print "return none", len(response)
+        return None
+    assert len(response) >= RESPONSE_LEN
+    version,status,port = struct.unpack("!BBH",response[:4])
+    assert version == 0
+    assert port == 0
+    if status == 90:
+        return "%d.%d.%d.%d"%tuple(map(ord, response[4:]))
+    else:
+        return "ERROR (status %d)"%status
+
+def socks5Hello():
+    return "\x05\x01\x00"
+def socks5ParseHello(response):
+    if response != "\x05\x00":
+        raise ValueError("Bizarre socks5 response")
+def socks5ResolveRequest(hostname):
+    version = 5
+    command = 0xF0
+    rsv = 0
+    port = 0
+    atype = 0x03
+    reqheader = struct.pack("!BBBB",version, command, rsv, atype)
+    portstr = struct.pach("!H",port)
+    return "%s%s\0%s"%(reqheader,hostname,port)
+def socks5ParseResponse(r):
+    if len(r)<8: return None
+    version, reply, rsv, atype = struct.unpack("!BBBB",r[:4])
+    assert version==5
+    assert rsv==0
+    if reply != 0x00:
+        return "ERROR"
+    assert atype in (0x01,0x04)
+    expected_len = 4 + ({1:4,4:16}[atype]) + 2
+    if len(r) < expected_len:
+        return None
+    elif len(r) > expected_len:
+        raise ValueError("Overlong socks5 reply!")
+    addr = r[4:-2]
+    if atype == 0x01:
+        return "%d.%d.%d.%d"%tuple(map(ord,addr))
+    else:
+        # not really the right way to format IPv6
+        return "IPv6: %s"%(":".join([hex(ord(c)) for c in addr]))
+
+def parseHostAndPort(h):
+    host, port = "localhost", 9050
+    if ":" in h:
+        i = h.index(":")
+        host = h[:i]
+        try:
+            port = int(h[i+1:])
+        except ValueError:
+            print "Bad hostname %r"%h
+            sys.exit(1)
+    elif h:
+        try:
+            port = int(h)
+        except ValueError:
+            host = h
+
+    return host, port
+
+def resolve(hostname, sockshost, socksport, socksver=4):
+    assert socksver in (4,5)
+    if socksver == 4:
+        fmt = socks4AResolveRequest
+        parse = socks4AParseResponse
+    else:
+        fmt = socks5ResolveRequest
+        parse = socks5ParseResponse
+    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+    s.connect((sockshost,socksport))
+    if socksver == 5:
+        s.send(socks5Hello())
+        socksParseHello(s.recv(2))
+    s.send(fmt(hostname))
+    answer = s.recv(8)
+    result = parse(answer)
+    while result is None:
+        answer += s.recv(1)
+        result = parse(answer)
+    print "Got answer",result
+    m = s.recv(1)
+    if m:
+        print "Got extra data too! Ick."
+    return result
+
+if __name__ == '__main__':
+    if len(sys.argv) not in (2,3,4):
+        print "Syntax: resolve.py [-4|-5] hostname [sockshost:socksport]"
+        sys.exit(0)
+    if sys.argv[1] in ("-4", "-5"):
+        socksver = int(sys.argv[1][1])
+        del sys.argv[1]
+    if len(sys.argv) == 4:
+        print "Syntax: resolve.py [-4|-5] hostname [sockshost:socksport]"
+        sys.exit(0)
+    if len(sys.argv) == 3:
+        sh,sp = parseHostAndPort(sys.argv[2])
+    else:
+        sh,sp = parseHostAndPort("")
+    resolve(sys.argv[1], sh, sp)