1 files changed, 61 insertions, 0 deletions
diff --git a/netaddr/ip/rfc1924.py b/netaddr/ip/rfc1924.py
new file mode 100644
index 0000000..54fb96c
--- /dev/null
+++ b/netaddr/ip/rfc1924.py
@@ -0,0 +1,61 @@
+#-----------------------------------------------------------------------------
+#   Copyright (c) 2008 by David P. D. Moss. All rights reserved.
+#
+#   Released under the BSD license. See the LICENSE file for details.
+#-----------------------------------------------------------------------------
+"""A basic implementation of RFC 1924 ;-)"""
+
+from netaddr.core import AddrFormatError
+from netaddr.ip import IPAddress
+
+from netaddr.compat import _zip
+
+
+def chr_range(low, high):
+    """Returns all characters between low and high chars."""
+    return [chr(i) for i in range(ord(low), ord(high) + 1)]
+
+#: Base 85 integer index to character lookup table.
+BASE_85 = (
+    chr_range('0', '9') + chr_range('A', 'Z') +
+    chr_range('a', 'z') +
+    ['!', '#', '$', '%', '&', '(', ')', '*', '+', '-', ';', '<', '=', '>',
+     '?', '@', '^', '_', '`', '{', '|', '}', '~']
+)
+
+#: Base 85 digit to integer lookup table.
+BASE_85_DICT = dict(_zip(BASE_85, range(0, 86)))
+
+
+def ipv6_to_base85(addr):
+    """Convert a regular IPv6 address to base 85."""
+    ip = IPAddress(addr)
+    int_val = int(ip)
+
+    remainder = []
+    while int_val > 0:
+        remainder.append(int_val % 85)
+        int_val //= 85
+
+    encoded = ''.join([BASE_85[w] for w in reversed(remainder)])
+    leading_zeroes = (20 - len(encoded)) * "0"
+    return leading_zeroes + encoded
+
+
+def base85_to_ipv6(addr):
+    """
+    Convert a base 85 IPv6 address to its hexadecimal format.
+    """
+    tokens = list(addr)
+
+    if len(tokens) != 20:
+        raise AddrFormatError('Invalid base 85 IPv6 address: %r' % (addr,))
+
+    result = 0
+    for i, num in enumerate(reversed(tokens)):
+        num = BASE_85_DICT[num]
+        result += (num * 85 ** i)
+
+    ip = IPAddress(result, 6)
+
+    return str(ip)