patch-2.4.20 linux-2.4.20/net/ipv4/netfilter/ipt_DSCP.c

• Lines: 109
• Date: Thu Nov 28 15:53:15 2002
• Orig file: linux-2.4.19/net/ipv4/netfilter/ipt_DSCP.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -urN linux-2.4.19/net/ipv4/netfilter/ipt_DSCP.c linux-2.4.20/net/ipv4/netfilter/ipt_DSCP.c
@@ -0,0 +1,108 @@
+/* iptables module for setting the IPv4 DSCP field, Version 1.8
+ *
+ * (C) 2002 by Harald Welte <laforge@gnumonks.org>
+ * based on ipt_FTOS.c (C) 2000 by Matthew G. Marsh <mgm@paktronix.com>
+ * This software is distributed under GNU GPL v2, 1991
+ * 
+ * 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@gnumonks.org>");
+MODULE_DESCRIPTION("IP tables DSCP modification module");
+MODULE_LICENSE("GPL");
+
+static unsigned int
+target(struct sk_buff **pskb,
+       unsigned int hooknum,
+       const struct net_device *in,
+       const struct net_device *out,
+       const void *targinfo,
+       void *userinfo)
+{
+	struct iphdr *iph = (*pskb)->nh.iph;
+	const struct ipt_DSCP_info *dinfo = targinfo;
+	u_int8_t sh_dscp = ((dinfo->dscp << IPT_DSCP_SHIFT) & IPT_DSCP_MASK);
+
+
+	if ((iph->tos & IPT_DSCP_MASK) != sh_dscp) {
+		u_int16_t diffs[2];
+
+		/* raw socket (tcpdump) may have clone of incoming
+		 * skb: don't disturb it --RR */
+		if (skb_cloned(*pskb) && !(*pskb)->sk) {
+			struct sk_buff *nskb = skb_copy(*pskb, GFP_ATOMIC);
+			if (!nskb)
+				return NF_DROP;
+			kfree_skb(*pskb);
+			*pskb = nskb;
+			iph = (*pskb)->nh.iph;
+		}
+
+		diffs[0] = htons(iph->tos) ^ 0xFFFF;
+		iph->tos = (iph->tos & ~IPT_DSCP_MASK) | sh_dscp;
+		diffs[1] = htons(iph->tos);
+		iph->check = csum_fold(csum_partial((char *)diffs,
+		                                    sizeof(diffs),
+		                                    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
+= { { NULL, NULL }, "DSCP", target, checkentry, NULL, THIS_MODULE };
+
+static int __init init(void)
+{
+	if (ipt_register_target(&ipt_dscp_reg))
+		return -EINVAL;
+
+	return 0;
+}
+
+static void __exit fini(void)
+{
+	ipt_unregister_target(&ipt_dscp_reg);
+}
+
+module_init(init);
+module_exit(fini);