From: Bob Halley <halley@dnspython.org>
Date: Mon, 1 Sep 2014 00:29:41 +0000 (-0700)
Subject: Add dns.ipv6.is_mapped(); Reverse IPv6 mapped IPv4 into v4 space.
X-Git-Tag: v1.12.0-py3~4
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=889e1e7342b54687f491c4521c4329ef1feb8b8f;p=thirdparty%2Fdnspython.git

Add dns.ipv6.is_mapped(); Reverse IPv6 mapped IPv4 into v4 space.
---

diff --git a/dns/ipv6.py b/dns/ipv6.py
index 73f62320..e2c01640 100644
--- a/dns/ipv6.py
+++ b/dns/ipv6.py
@@ -155,3 +155,8 @@ def inet_aton(text):
         return bytes.fromhex(text)
     except:
         raise dns.exception.SyntaxError
+
+_mapped_prefix = b'\x00' * 10 + b'\xff\xff'
+
+def is_mapped(address):
+    return address.startswith(_mapped_prefix)
diff --git a/dns/reversename.py b/dns/reversename.py
index f8bd9e0f..276393c2 100644
--- a/dns/reversename.py
+++ b/dns/reversename.py
@@ -39,8 +39,13 @@ def from_address(text):
     @rtype: dns.name.Name object
     """
     try:
-        parts = ['%x.%x' % (byte & 0x0f, byte >> 4) for byte in dns.ipv6.inet_aton(text)]
-        origin = ipv6_reverse_domain
+        v6 = dns.ipv6.inet_aton(text)
+        if dns.ipv6.is_mapped(v6):
+            parts = ['%d' % byte for byte in v6[12:]]
+            origin = ipv4_reverse_domain
+        else:
+            parts = ['%x.%x' % (byte & 0x0f, byte >> 4) for byte in v6]
+            origin = ipv6_reverse_domain
     except:
         parts = ['%d' % byte for byte in dns.ipv4.inet_aton(text)]
         origin = ipv4_reverse_domain
diff --git a/tests/name.py b/tests/name.py
index 21394093..c125a156 100644
--- a/tests/name.py
+++ b/tests/name.py
@@ -660,6 +660,11 @@ class NameTestCase(unittest.TestCase):
         n = dns.reversename.from_address('::1')
         self.assertTrue(e == n)
 
+    def testReverseIPv6MappedIpv4(self):
+        e = dns.name.from_text('1.0.0.127.in-addr.arpa.')
+        n = dns.reversename.from_address('::ffff:127.0.0.1')
+        self.assertTrue(e == n)
+
     def testBadReverseIPv4(self):
         def bad():
             n = dns.reversename.from_address('127.0.foo.1')
diff --git a/tests/ntoaaton.py b/tests/ntoaaton.py
index bef83f37..92ccc817 100644
--- a/tests/ntoaaton.py
+++ b/tests/ntoaaton.py
@@ -199,5 +199,13 @@ class NtoAAtoNTestCase(unittest.TestCase):
         t1 = ntoa6(b1)
         self.assertTrue(t1 == addr)
 
+    def test_is_mapped(self):
+        t1 = '2001:db8:0:1:1:1:1:1'
+        t2 = '::ffff:127.0.0.1'
+        t3 = '1::ffff:127.0.0.1'
+        self.assertFalse(dns.ipv6.is_mapped(aton6(t1)))
+        self.assertTrue(dns.ipv6.is_mapped(aton6(t2)))
+        self.assertFalse(dns.ipv6.is_mapped(aton6(t3)))
+
 if __name__ == '__main__':
     unittest.main()