decode_vrrp.c

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/*
 * decode_vrrp.c
 *
 * Virtual Router Redundancy Protocol.
 *
 * Copyright (c) 2000 Eric Jackson <ericj@monkey.org>
 * Copyright (c) 2000 Dug Song <dugsong@monkey.org>
 *
 * $Id: decode_vrrp.c,v 1.5 2001/03/15 08:33:03 dugsong Exp $
 */
 
#include "config.h"
 
#include <sys/types.h>
 
#include <stdio.h>
#include <string.h>
 
#include "buf.h"
#include "decode.h"
 
struct vrrp_header {
    u_char  vr_vers;    /* Version */
    u_char  vr_vrid;    /* Virtual Router ID */
    u_char  vr_prio;    /* Router Priority */
    u_char  vr_naddr;   /* # of addresses */
    u_char  vr_auth;    /* Type of Authentication */
    u_char  vr_advr;    /* ADVERTISEMENT Interval */
    u_short vr_cksum;   /* Checksum */
    /* vr_naddr * 4 # of addresses */
};
#define VRRP_AUTH_NONE      0
#define VRRP_AUTH_SIMPLE    1
#define VRRP_AUTH_AH        2
 
#define VRRP_AUTH_DATA_LEN  8
 
int
decode_vrrp(u_char *buf, int len, u_char *obuf, int olen)
{
    struct buf *b, inbuf, outbuf;
    struct vrrp_header *vrrp;
 
    buf_init(&inbuf, buf, len);
    buf_init(&outbuf, obuf, olen);
    
    vrrp = (struct vrrp_header *)buf_ptr(&inbuf);
    
    if (buf_len(&inbuf) < sizeof(*vrrp))
        return (0);
    
    /* We only care about VRRP_AUTH_SIMPLE */
    if (ntohs(vrrp->vr_auth) != VRRP_AUTH_SIMPLE)
        return (0);
    
    /* XXX - probably want to verify checksum */
    
    /* Forward to Authentication Data */
    buf_skip(&inbuf, sizeof(*vrrp) + 8 + (vrrp->vr_naddr * 4));
 
    if ((b = buf_tok(&inbuf, NULL, VRRP_AUTH_DATA_LEN)) == NULL)
        return (0);
    
    buf_put(&outbuf, buf_ptr(b), buf_len(b));
    buf_put(&outbuf, "\n", 1);
    buf_end(&outbuf);
    
    return (buf_len(&outbuf));
}