git-svn-id: https://map66.svn.sourceforge.net/svnroot/map66@42 3484d885-4da6-438d-b19d-107d078dd756

1 files changed, 58 insertions, 10 deletions

diff --git a/ip6t_MAP66.c b/ip6t_MAP66.c
index 66f5172..2f880e5 100644
--- a/ip6t_MAP66.c
+++ b/ip6t_MAP66.c
@@ -7,6 +7,7 @@
 #include <linux/module.h>
 #include <linux/version.h>
 #include <linux/netfilter_ipv6/ip6_tables.h>
+#include <linux/dccp.h>
 #include <net/ipv6.h>
 
 #include "ip6t_MAP66.h"
@@ -36,16 +37,31 @@ static inline u_int16_t csum16(const u_int16_t *buf, int len)
 static void map16(
 	struct in6_addr* addr,
 	const struct in6_addr* to,
-	int len,
-	u_int16_t csum)
+	int len_to,
+	u_int16_t csum_to)
 {
-	csum = add16(
-		*((u_int16_t*)addr + len),
-		add16(csum16((const u_int16_t *)addr, len), csum)
+	csum_to = add16(
+		*((u_int16_t*)addr + len_to),
+		add16(csum16((const u_int16_t *)addr, len_to), csum_to)
 	);
-	if (csum == 0xffff) csum = 0x0000;
-	*((u_int16_t *)addr + len) = csum;
-	memcpy(addr, to, sizeof(u_int16_t) * len);
+	if (csum_to == 0xffff) csum_to = 0x0000;
+	*((u_int16_t *)addr + len_to) = csum_to;
+	memcpy(addr, to, sizeof(u_int16_t) * len_to);
+}
+
+/* Perform mapping with csum update */
+static void map_csum(
+	struct in6_addr* addr,
+	const struct in6_addr* to,
+	int len_to,
+	u_int16_t csum_to,
+	u_int16_t* csum_transport)
+{
+	*csum_transport = ~add16(
+		~csum_to,
+		add16(~*csum_transport, ~csum16((u_int16_t *)&addr, len_to))
+	);
+	memcpy(addr, to, sizeof(u_int16_t) * len_to);
 }
 
 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,5,0)
@@ -123,6 +139,7 @@ static unsigned int MAP66_tg6(
 	struct sk_buff *skb,
 	const struct xt_target_param *par)
 {
+	u_int16_t* csum_transport = NULL;
 	struct ipv6hdr *hdr = ipv6_hdr(skb);
 	const struct ip6t_MAP66_info *info = par->targinfo;
 
@@ -151,13 +168,44 @@ static unsigned int MAP66_tg6(
 	hdr = ipv6_hdr(skb);
 #endif
 
+	if (0 != (IP6T_MAP66_OPT_CSUM & info->mapflags)) {
+		u8 nexthdr = hdr->nexthdr;
+		int hoff = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &nexthdr);
+		if (hoff < 0) {
+			pr_devel("MAP66: Unsupported packet dropped\n");
+			return NF_DROP;
+		}
+		switch(nexthdr) {
+			case IPPROTO_TCP:
+				csum_transport = skb_header_pointer(
+					skb, hoff+offsetof(struct tcphdr, check), 0, NULL);
+			break;
+			case IPPROTO_UDP:
+			case IPPROTO_UDPLITE:
+				csum_transport = skb_header_pointer(
+					skb, hoff+offsetof(struct udphdr, check), 0, NULL);
+			break;
+			case IPPROTO_DCCP:
+				csum_transport = skb_header_pointer(
+					skb, hoff+offsetof(struct dccp_hdr, dccph_checksum), 0, NULL);
+			break;
+			case IPPROTO_ICMPV6:
+				csum_transport = skb_header_pointer(
+					skb, hoff+offsetof(struct icmp6hdr, icmp6_cksum), 0, NULL);
+			break;
+			default:
+				pr_devel("MAP66: Unsupported protocol %d\n", nexthdr);
+				return NF_DROP;
+		}
+	}
+
 	if (0 != (IP6T_MAP66_OPT_DST_TO & info->mapflags)) {
 		pr_devel("MAP66: DST_TO, ip_summed=%d\n", skb->ip_summed);
 		if (0 != (IP6T_MAP66_OPT_NOCHECK & info->mapflags) || !is_my_ipv6_addr(
 			NF_INET_PRE_ROUTING == par->hooknum ? par->in : par->out, &hdr->daddr))
 		{
 			if (0 != (IP6T_MAP66_OPT_CSUM & info->mapflags)) {
-				memcpy(&hdr->daddr, &info->pfix_dst_to, sizeof(u_int16_t) * info->pfix_dst_len);
+				map_csum(&hdr->daddr, &info->pfix_dst_to, info->pfix_dst_len, info->pfix_dst_csum, csum_transport);
 			}
 			else {
 				map16(&hdr->daddr, &info->pfix_dst_to, info->pfix_dst_len, info->pfix_dst_csum);
@@ -168,7 +216,7 @@ static unsigned int MAP66_tg6(
 	if (0 != (IP6T_MAP66_OPT_SRC_TO & info->mapflags)) {
 		pr_devel("MAP66: SRC_TO, ip_summed=%d\n", skb->ip_summed);
 		if (0 != (IP6T_MAP66_OPT_CSUM & info->mapflags)) {
-			memcpy(&hdr->saddr, &info->pfix_src_to, sizeof(u_int16_t) * info->pfix_src_len);
+			map_csum(&hdr->saddr, &info->pfix_src_to, info->pfix_src_len, info->pfix_src_csum, csum_transport);
 		}
 		else {
 			map16(&hdr->saddr, &info->pfix_src_to, info->pfix_src_len, info->pfix_src_csum);