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add length checks and comments to proxy LCP parsing

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This commit is contained in:
Brendan O'Dea 2004-11-05 02:25:25 +00:00
parent 0ac369f083
commit 4da9597503
1 changed files with 7 additions and 23 deletions
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30
l2tpns.c
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@ -4,7 +4,7 @@
// Copyright (c) 2002 FireBrick (Andrews & Arnold Ltd / Watchfront Ltd) - GPL licenced
// vim: sw=8 ts=8
char const *cvs_id_l2tpns = "$Id: l2tpns.c,v 1.41 2004-11-04 06:05:55 bodea Exp $";
char const *cvs_id_l2tpns = "$Id: l2tpns.c,v 1.42 2004-11-05 02:25:25 bodea Exp $";
#include <arpa/inet.h>
#include <assert.h>
@ -1668,39 +1668,23 @@ void processudp(u8 * buf, int len, struct sockaddr_in *addr)
case 27: // last send lcp
{ // find magic number
u8 *p = b, *e = p + n;
while (p < e && p[1])
while (p + 1 < e && p[1] && p + p[1] <= e)
{
if (*p == 5 && p[1] == 6)
if (*p == 5 && p[1] == 6) // Magic-Number
amagic = ntohl(*(u32 *) (p + 2));
else if (*p == 3 && p[1] == 5 && *(u16 *) (p + 2) == htons(PPPCHAP) && p[4] == 5)
else if (*p == 3 && p[1] == 5 && *(u16 *) (p + 2) == htons(PPPCHAP) && p[4] == 5) // Authentication-Protocol
chap = 1;
else if (*p == 7)
else if (*p == 7) // Protocol-Field-Compression
aflags |= SESSIONPFC;
else if (*p == 8)
else if (*p == 8) // Address-and-Control-Field-Compression
aflags |= SESSIONACFC;
p += p[1];
}
{
char tmp[500] = {0};
tmp[0] = ConfigReq;
memcpy((tmp + 1), b, n);
}
}
break;
case 28: // last recv lcp confreq
{
char tmp[500] = {0};
tmp[0] = ConfigReq;
memcpy((tmp + 1), b, n);
break;
}
break;
case 26: // Initial Received LCP CONFREQ
{
char tmp[500] = {0};
tmp[0] = ConfigReq;
memcpy((tmp + 1), b, n);
}
break;
case 39: // seq required - we control it as an LNS anyway...
break;