add ipv6 unicast nlri encode and decode basic func

Signed-off-by: Peng Xiao <xiaoquwl@gmail.com>

yabgp/message/attribute/nlri/ipv6_unicast.py

@@ -0,0 +1,58 @@
+# Copyright 2015 Cisco Systems, Inc.
+# All rights reserved.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+""" IPv6 Unicast """
+
+import struct
+import binascii
+import netaddr
+
+
+class IPv6Unicast(object):
+
+    @staticmethod
+    def parse(nlri_data):
+        """
+        decode IPv6 NLRI data
+        :param nlri_data: NLRI raw hex data
+        :return: return the results after decoding.
+        """
+        nlri_list = []
+        while nlri_data:
+            prefix_bit_len = struct.unpack('!B', nlri_data[0])[0]
+            if prefix_bit_len % 8 == 0:
+                prefix_byte_len = prefix_bit_len / 8
+            else:
+                prefix_byte_len = prefix_bit_len / 8 + 1
+            prefix_addr = netaddr.IPAddress(int(binascii.b2a_hex(nlri_data[1:prefix_byte_len + 1]), 16)).__str__() \
+                + '/%s' % prefix_bit_len
+            nlri_list.append(prefix_addr)
+            nlri_data = nlri_data[prefix_byte_len + 1:]
+
+        return nlri_list
+
+    @staticmethod
+    def construct(nlri_list):
+        """
+        Construct NLRI from list to hex data
+        :param nlri_list:
+        :return:
+        """
+        nlri_hex = b''
+        for prefix in nlri_list:
+            prefix = netaddr.IPNetwork(prefix)
+            nlri_hex += struct.pack('!B', prefix.prefixlen)
+            nlri_hex += binascii.unhexlify(hex(prefix.ip)[2:])
+        return nlri_hex

yabgp/tests/unit/message/attribute/nlri/test_ipv6_unicast.py

@@ -0,0 +1,53 @@
+# Copyright 2015 Cisco Systems, Inc.
+# All rights reserved.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+""" Test IPv6 Unicast """
+
+import unittest
+
+from yabgp.message.attribute.nlri.ipv6_unicast import IPv6Unicast
+
+
+class TestIPv6Unicast(unittest.TestCase):
+    def test_parse(self):
+        nlri_data = b'\x80\x20\x01\x32\x32\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01\x40\x20\x01\x32' \
+                    b'\x32\x00\x01\x00\x00\x7f\x20\x01\x48\x37\x16\x32\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02'
+        value_parsed = IPv6Unicast().parse(nlri_data)
+        value_hoped = ['2001:3232::1/128', '::2001:3232:1:0/64', '2001:4837:1632::2/127']
+        self.assertEqual(value_hoped, value_parsed)
+
+    def test_parse_withdraw(self):
+        nlri_data = b'\x40\x20\x01\x0d\xb8\x00\x01\x00\x02\x40\x20\x01\x0d\xb8\x00\x01\x00\x01\x40\x20\x01\x0d' \
+                    b'\xb8\x00\x01\x00\x00'
+        value_parsed = IPv6Unicast.parse(nlri_data)
+        value_hoped = ['::2001:db8:1:2/64', '::2001:db8:1:1/64', '::2001:db8:1:0/64']
+        self.assertEqual(value_hoped, value_parsed)
+
+    def test_construct_nlri(self):
+        nlri_list = ['::2001:db8:1:2/64', '::2001:db8:1:1/64', '::2001:db8:1:0/64']
+        value_hex = IPv6Unicast.construct(nlri_list)
+        value_hoped = b'\x40\x20\x01\x0d\xb8\x00\x01\x00\x02\x40\x20\x01\x0d\xb8\x00\x01\x00\x01\x40\x20\x01\x0d' \
+                      b'\xb8\x00\x01\x00\x00'
+        self.assertEqual(value_hoped, value_hex)
+
+    def test_construct_nlri_2(self):
+        nlri_list = ['2001:3232::1/128', '::2001:3232:1:0/64', '2001:4837:1632::2/127']
+        value_hex = IPv6Unicast.construct(nlri_list)
+        value_hoped = b'\x80\x20\x01\x32\x32\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01\x40\x20\x01\x32' \
+                      b'\x32\x00\x01\x00\x00\x7f\x20\x01\x48\x37\x16\x32\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02'
+        self.assertEqual(value_hoped, value_hex)
+
+if __name__ == '__main__':
+    unittest.main()