From 0190c6f516b9bd9e917f32329853b512b51eb4a2 Mon Sep 17 00:00:00 2001
From: Arnaud Ebalard <arno@natisbad.org>
Date: Mon, 2 Nov 2009 21:03:29 +0100
Subject: [PATCH] Added in6_get_common_plen()
---
scapy/utils6.py | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)
diff --git a/scapy/utils6.py b/scapy/utils6.py
index 1b7a8c0d..17c94b4c 100644
--- a/scapy/utils6.py
+++ b/scapy/utils6.py
@@ -700,3 +700,22 @@ def in6_getscope(addr):
else:
scope = -1
return scope
+
+def in6_get_common_plen(a, b):
+ """
+ Return common prefix length of IPv6 addresses a and b.
+ """
+ def matching_bits(byte1, byte2):
+ for i in range(8):
+ cur_mask = 0x80 >> i
+ if (byte1 & cur_mask) != (byte2 & cur_mask):
+ return i
+ return 8
+
+ tmpA = inet_pton(socket.AF_INET6, a)
+ tmpB = inet_pton(socket.AF_INET6, b)
+ for i in range(16):
+ mbits = matching_bits(ord(tmpA[i]), ord(tmpB[i]))
+ if mbits != 8:
+ return 8*i + mbits
+ return 128
--
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