| /* iptables module for setting the IPv4 DSCP field, Version 1.8 |
| * |
| * (C) 2002 by Harald Welte <laforge@netfilter.org> |
| * based on ipt_FTOS.c (C) 2000 by Matthew G. Marsh <mgm@paktronix.com> |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License version 2 as |
| * published by the Free Software Foundation. |
| * |
| * See RFC2474 for a description of the DSCP field within the IP Header. |
| * |
| * ipt_DSCP.c,v 1.8 2002/08/06 18:41:57 laforge Exp |
| */ |
| |
| #include <linux/module.h> |
| #include <linux/skbuff.h> |
| #include <linux/ip.h> |
| #include <net/checksum.h> |
| |
| #include <linux/netfilter_ipv4/ip_tables.h> |
| #include <linux/netfilter_ipv4/ipt_DSCP.h> |
| |
| MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>"); |
| MODULE_DESCRIPTION("iptables DSCP modification module"); |
| MODULE_LICENSE("GPL"); |
| |
| static unsigned int |
| target(struct sk_buff **pskb, |
| const struct net_device *in, |
| const struct net_device *out, |
| unsigned int hooknum, |
| const void *targinfo, |
| void *userinfo) |
| { |
| const struct ipt_DSCP_info *dinfo = targinfo; |
| u_int8_t sh_dscp = ((dinfo->dscp << IPT_DSCP_SHIFT) & IPT_DSCP_MASK); |
| |
| |
| if (((*pskb)->nh.iph->tos & IPT_DSCP_MASK) != sh_dscp) { |
| u_int16_t diffs[2]; |
| |
| if (!skb_ip_make_writable(pskb, sizeof(struct iphdr))) |
| return NF_DROP; |
| |
| diffs[0] = htons((*pskb)->nh.iph->tos) ^ 0xFFFF; |
| (*pskb)->nh.iph->tos = ((*pskb)->nh.iph->tos & ~IPT_DSCP_MASK) |
| | sh_dscp; |
| diffs[1] = htons((*pskb)->nh.iph->tos); |
| (*pskb)->nh.iph->check |
| = csum_fold(csum_partial((char *)diffs, |
| sizeof(diffs), |
| (*pskb)->nh.iph->check |
| ^ 0xFFFF)); |
| (*pskb)->nfcache |= NFC_ALTERED; |
| } |
| return IPT_CONTINUE; |
| } |
| |
| static int |
| checkentry(const char *tablename, |
| const struct ipt_entry *e, |
| void *targinfo, |
| unsigned int targinfosize, |
| unsigned int hook_mask) |
| { |
| const u_int8_t dscp = ((struct ipt_DSCP_info *)targinfo)->dscp; |
| |
| if (targinfosize != IPT_ALIGN(sizeof(struct ipt_DSCP_info))) { |
| printk(KERN_WARNING "DSCP: targinfosize %u != %Zu\n", |
| targinfosize, |
| IPT_ALIGN(sizeof(struct ipt_DSCP_info))); |
| return 0; |
| } |
| |
| if (strcmp(tablename, "mangle") != 0) { |
| printk(KERN_WARNING "DSCP: can only be called from \"mangle\" table, not \"%s\"\n", tablename); |
| return 0; |
| } |
| |
| if ((dscp > IPT_DSCP_MAX)) { |
| printk(KERN_WARNING "DSCP: dscp %x out of range\n", dscp); |
| return 0; |
| } |
| |
| return 1; |
| } |
| |
| static struct ipt_target ipt_dscp_reg = { |
| .name = "DSCP", |
| .target = target, |
| .checkentry = checkentry, |
| .me = THIS_MODULE, |
| }; |
| |
| static int __init init(void) |
| { |
| return ipt_register_target(&ipt_dscp_reg); |
| } |
| |
| static void __exit fini(void) |
| { |
| ipt_unregister_target(&ipt_dscp_reg); |
| } |
| |
| module_init(init); |
| module_exit(fini); |