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Add note about ::/96 being deprecated. 

svn path=/trunk/; revision=37008
This commit is contained in:
Jakub Zawadzki 2011-05-06 11:39:11 +00:00
parent 02d50e354b
commit 4194ee7f89
1 changed files with 23 additions and 0 deletions
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23
epan/address_to_str.c
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@ -197,6 +197,29 @@ ip6_to_str_buf_len(const guchar* src, char *buf, size_t buf_len)
best.base = -1;
/* Is this address an encapsulated IPv4? */
/* XXX,
* Orginal code dated 1996 uses ::/96 as a valid IPv4-compatible addresses
* but since Feb 2006 ::/96 is deprecated one.
* Quoting wikipedia [0]:
* > The 96-bit zero-value prefix ::/96, originally known as IPv4-compatible
* > addresses, was mentioned in 1995[35] but first described in 1998.[41]
* > This class of addresses was used to represent IPv4 addresses within
* > an IPv6 transition technology. Such an IPv6 address has its first
* > (most significant) 96 bits set to zero, while its last 32 bits are the
* > IPv4 address that is represented.
* > In February 2006 the Internet Engineering Task Force (IETF) has deprecated
* > the use of IPv4-compatible addresses.[1] The only remaining use of this address
* > format is to represent an IPv4 address in a table or database with fixed size
* > members that must also be able to store an IPv6 address.
*
* If needed it can be fixed by changing next line:
* if (best.base == 0 && (best.len == 6 || (best.len == 5 && words[5] == 0xffff)))
* to:
* if (best.base == 0 && best.len == 5 && words[5] == 0xffff)
*
* [0] http://en.wikipedia.org/wiki/IPv6_address#Historical_notes
*/
if (best.base == 0 && (best.len == 6 || (best.len == 5 && words[5] == 0xffff)))
{
/* best.len == 6 -> ::IPv4; 5 -> ::ffff:IPv4 */