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Explain the dual use of struct prefix for CIDR prefixes and

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address/netmask pairs, and clarify the two comparison functions.
This commit is contained in:
gdt 2004-01-13 14:55:40 +00:00
parent a27abaa5c2
commit 9d24baaa3d
2 changed files with 27 additions and 3 deletions
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21
lib/prefix.c
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@ -118,7 +118,14 @@ prefix_copy (struct prefix *dest, struct prefix *src)
}
}
/* If both prefix structure is same then return 1 else return 0. */
/*
* Return 1 if the address/netmask contained in the prefix structure
* is the same, and else return 0. For this routine, 'same' requires
* that not only the prefix length and the network part be the same,
* but also the host part. Thus, 10.0.0.1/8 and 10.0.0.2/8 are not
* the same. Note that this routine has the same return value sense
* as '==' (which is different from prefix_cmp).
*/
int
prefix_same (struct prefix *p1, struct prefix *p2)
{
@ -136,8 +143,16 @@ prefix_same (struct prefix *p1, struct prefix *p2)
return 0;
}
/* When both prefix structure is not same, but will be same after
applying mask, return 0. otherwise, return 1 */
/*
* Return 0 if the network prefixes represented by the struct prefix
* arguments are the same prefix, and 1 otherwise. Network prefixes
* are considered the same if the prefix lengths are equal and the
* network parts are the same. Host bits (which are considered masked
* by the prefix length) are not significant. Thus, 10.0.0.1/8 and
* 10.0.0.2/8 are considered equivalent by this routine. Note that
* this routine has the same return sense as strcmp (which is different
* from prefix_same).
*/
int
prefix_cmp (struct prefix *p1, struct prefix *p2)
{

9
lib/prefix.h
View file

@ -23,6 +23,15 @@
#ifndef _ZEBRA_PREFIX_H
#define _ZEBRA_PREFIX_H
/*
* A struct prefix contains an address family, a prefix length, and an
* address. This can represent either a 'network prefix' as defined
* by CIDR, where the 'host bits' of the prefix are 0
* (e.g. AF_INET:10.0.0.0/8), or an address and netmask
* (e.g. AF_INET:10.0.0.9/8), such as might be configured on an
* interface.
*/
/* IPv4 and IPv6 unified prefix structure. */
struct prefix
{