1 files changed, 75 insertions, 0 deletions
diff --git a/third_party/dnspython/dns/reversename.py b/third_party/dnspython/dns/reversename.py
new file mode 100644
index 0000000000..4925cfd6ff
--- /dev/null
+++ b/third_party/dnspython/dns/reversename.py
@@ -0,0 +1,75 @@
+# Copyright (C) 2006, 2007, 2009-2011 Nominum, Inc.
+#
+# Permission to use, copy, modify, and distribute this software and its
+# documentation for any purpose with or without fee is hereby granted,
+# provided that the above copyright notice and this permission notice
+# appear in all copies.
+#
+# THE SOFTWARE IS PROVIDED "AS IS" AND NOMINUM DISCLAIMS ALL WARRANTIES
+# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL NOMINUM BE LIABLE FOR
+# ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+# ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
+# OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+
+"""DNS Reverse Map Names.
+
+@var ipv4_reverse_domain: The DNS IPv4 reverse-map domain, in-addr.arpa.
+@type ipv4_reverse_domain: dns.name.Name object
+@var ipv6_reverse_domain: The DNS IPv6 reverse-map domain, ip6.arpa.
+@type ipv6_reverse_domain: dns.name.Name object
+"""
+
+import dns.name
+import dns.ipv6
+import dns.ipv4
+
+ipv4_reverse_domain = dns.name.from_text('in-addr.arpa.')
+ipv6_reverse_domain = dns.name.from_text('ip6.arpa.')
+
+def from_address(text):
+    """Convert an IPv4 or IPv6 address in textual form into a Name object whose
+    value is the reverse-map domain name of the address.
+    @param text: an IPv4 or IPv6 address in textual form (e.g. '127.0.0.1',
+    '::1')
+    @type text: str
+    @rtype: dns.name.Name object
+    """
+    try:
+        parts = list(dns.ipv6.inet_aton(text).encode('hex_codec'))
+        origin = ipv6_reverse_domain
+    except:
+        parts = ['%d' % ord(byte) for byte in dns.ipv4.inet_aton(text)]
+        origin = ipv4_reverse_domain
+    parts.reverse()
+    return dns.name.from_text('.'.join(parts), origin=origin)
+
+def to_address(name):
+    """Convert a reverse map domain name into textual address form.
+    @param name: an IPv4 or IPv6 address in reverse-map form.
+    @type name: dns.name.Name object
+    @rtype: str
+    """
+    if name.is_subdomain(ipv4_reverse_domain):
+        name = name.relativize(ipv4_reverse_domain)
+        labels = list(name.labels)
+        labels.reverse()
+        text = '.'.join(labels)
+        # run through inet_aton() to check syntax and make pretty.
+        return dns.ipv4.inet_ntoa(dns.ipv4.inet_aton(text))
+    elif name.is_subdomain(ipv6_reverse_domain):
+        name = name.relativize(ipv6_reverse_domain)
+        labels = list(name.labels)
+        labels.reverse()
+        parts = []
+        i = 0
+        l = len(labels)
+        while i < l:
+            parts.append(''.join(labels[i:i+4]))
+            i += 4
+        text = ':'.join(parts)
+        # run through inet_aton() to check syntax and make pretty.
+        return dns.ipv6.inet_ntoa(dns.ipv6.inet_aton(text))
+    else:
+        raise dns.exception.SyntaxError('unknown reverse-map address family')