fix cut-n-paste error

[l2tpns.git] / l2tpns.c

diff --git a/l2tpns.c b/l2tpns.c
index 2c3f345..488287f 100644 (file)
--- a/l2tpns.c
+++ b/l2tpns.c
@@ -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 1.60 2004-11-29 02:17:17 bodea Exp $";
+char const *cvs_id_l2tpns = "$Id: l2tpns.c,v 1.61 2004-11-29 03:55:21 bodea Exp $";
 
 #include <arpa/inet.h>
 #include <assert.h>
@@ -4418,18 +4418,17 @@ int ip_filter(u8 *buf, int len, u8 filter)
        if (len < 20) // up to end of destination address
                return 0;
 
-       if (*buf >> 4) // IPv4
+       if ((*buf >> 4) != 4) // IPv4
                return 0;
 
-
-       frag_offset = ntohs(*(u16 *) (buf + 0)) & 0x1fff;
+       frag_offset = ntohs(*(u16 *) (buf + 6)) & 0x1fff;
        proto = buf[9];
        src_ip = *(u32 *) (buf + 12);
        dst_ip = *(u32 *) (buf + 16);
 
        if (frag_offset == 0 && (proto == IPPROTO_TCP || proto == IPPROTO_UDP))
        {
-               int l = buf[0] & 0xf;
+               int l = (buf[0] & 0xf) * 4; // length of IP header
                if (len < l + 4) // ports
                        return 0;
 
@@ -4437,16 +4436,16 @@ int ip_filter(u8 *buf, int len, u8 filter)
                dst_port = ntohs(*(u16 *) (buf + l + 2));
                if (proto == IPPROTO_TCP)
                {
-                       if (len < l + 15) // flags
+                       if (len < l + 14) // flags
                                return 0;
 
-                       flags = buf[l + 14] & 0x3f;
+                       flags = buf[l + 13] & 0x3f;
                }
        }
 
        for (rule = ip_filters[filter].rules; rule->action; rule++)
        {
-               if (proto && proto != rule->proto)
+               if (rule->proto != IPPROTO_IP && proto != rule->proto)
                        continue;
 
                if (rule->src_wild != INADDR_BROADCAST &&