add udp source port test

tests/test_udp_src.py

@@ -0,0 +1,31 @@
+#!/usr/bin/python
+
+import socket
+import socks
+
+if __name__ == '__main__':
+    sock_out = socks.socksocket(socket.AF_INET, socket.SOCK_DGRAM,
+                                socket.SOL_UDP)
+    sock_out.set_proxy(socks.SOCKS5, '127.0.0.1', 1081)
+    sock_out.bind(('127.0.0.1', 9000))
+
+    sock_in1 = socket.socket(socket.AF_INET, socket.SOCK_DGRAM,
+                             socket.SOL_UDP)
+    sock_in2 = socket.socket(socket.AF_INET, socket.SOCK_DGRAM,
+                             socket.SOL_UDP)
+
+    sock_in1.bind(('127.0.0.1', 9001))
+    sock_in2.bind(('127.0.0.1', 9002))
+
+    sock_out.sendto('data', ('127.0.0.1', 9001))
+    result1 = sock_in1.recvfrom(8)
+
+    sock_out.sendto('data', ('127.0.0.1', 9002))
+    result2 = sock_in2.recvfrom(8)
+
+    sock_out.close()
+    sock_in1.close()
+    sock_in2.close()
+
+    # make sure they're from the same source port
+    assert result1 == result2