1 files changed, 31 insertions, 48 deletions

diff --git a/ip6t_MAP66.c b/ip6t_MAP66.c
index ea04c7d..b863c1c 100644
--- a/ip6t_MAP66.c
+++ b/ip6t_MAP66.c
@@ -39,38 +39,25 @@ static inline u_int16_t csum16(const u_int16_t *buf, int len)
 	return csum;
 }
 
-/* Perform checksum neutral mapping */
-static void map16(
-	struct in6_addr* addr,
-	const struct in6_addr* to,
-	int len_to,
-	u_int16_t csum_to)
-{
-	csum_to = add16(
-		*((u_int16_t*)addr + len_to),
-		add16(csum16((const u_int16_t *)addr, len_to), csum_to)
-	);
-	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, see RFC 1624 */
-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)
+static void map16(
+	u_int16_t *dest,
+	const u_int16_t *source,
+	int len,
+	u_int16_t csum,
+	u_int16_t* pcsum)
 {
-	*csum_transport = ~add16(
+	if (NULL == pcsum) {
+		pcsum = dest + len;
+	}
+	*pcsum = ~add16(
 		add16(
-			~(*csum_transport),
-			~csum16((u_int16_t *)addr, len_to)
+			~(*pcsum),
+			~csum16(dest, len)
 		),
-		~csum_to
+		csum
 	);
-	memcpy(addr, to, len_to * 2);
+	memcpy(dest, source, len * sizeof(u_int16_t));
 }
 
 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,5,0)
@@ -146,7 +133,7 @@ static unsigned int MAP66_tg6(
 	struct sk_buff *skb,
 	const struct xt_target_param *par)
 {
-	u_int16_t* csum_transport = NULL;
+	u_int16_t* pcsum = NULL;
 	struct ipv6hdr *hdr = ipv6_hdr(skb);
 	const struct ip6t_MAP66_info *info = par->targinfo;
 
@@ -192,21 +179,21 @@ static unsigned int MAP66_tg6(
 		}
 		switch(nexthdr) {
 			case IPPROTO_TCP:
-				csum_transport = &((struct tcphdr*)transport)->check;
+				pcsum = &((struct tcphdr*)transport)->check;
 			break;
 			case IPPROTO_UDP:
 #if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,20)
 			case IPPROTO_UDPLITE:
 #endif
-				csum_transport = &((struct udphdr*)transport)->check;
+				pcsum = &((struct udphdr*)transport)->check;
 			break;
 #if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,14)
 			case IPPROTO_DCCP:
-				csum_transport = &((struct dccp_hdr*)transport)->dccph_checksum;
+				pcsum = &((struct dccp_hdr*)transport)->dccph_checksum;
 			break;
 #endif
 			case IPPROTO_ICMPV6:
-				csum_transport = &((struct icmp6hdr*)transport)->icmp6_cksum;
+				pcsum = &((struct icmp6hdr*)transport)->icmp6_cksum;
 			break;
 			default:
 				pr_devel("MAP66: Unsupported protocol %d dropped\n", nexthdr);
@@ -218,22 +205,14 @@ static unsigned int MAP66_tg6(
 		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)) {
-				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);
-			}
+			map16((u_int16_t *)&hdr->daddr, (u_int16_t *)&info->pfix_dst_to,
+				info->pfix_dst_len, info->pfix_dst_csum, pcsum);
 		}
 	}
 	
 	if (0 != (IP6T_MAP66_OPT_SRC_TO & info->mapflags)) {
-		if (0 != (IP6T_MAP66_OPT_CSUM & info->mapflags)) {
-			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);
-		}
+		map16((u_int16_t *)&hdr->saddr, (u_int16_t *)&info->pfix_src_to,
+			info->pfix_src_len, info->pfix_src_csum, pcsum);
 		if (0 == (IP6T_MAP66_OPT_NOCHECK & info->mapflags) && is_my_ipv6_addr(
 			NF_INET_PRE_ROUTING == par->hooknum ? par->in : par->out, &hdr->saddr))
 		{
@@ -263,10 +242,12 @@ static bool MAP66_tg6_check(
 	   (0 != (IP6T_MAP66_OPT_CSUM & info->mapflags) ? 8 : 7) < info->pfix_dst_len))
 	{
 		if (8 == info->pfix_dst_len) {
-			printk("MAP66: --" IP6T_MAP66_DST_TO " prefix length /%d only possible with --csum\n", 16 * info->pfix_dst_len);
+			printk("MAP66: --" IP6T_MAP66_DST_TO " prefix length /%d only "
+				"possible with --csum\n", 16 * info->pfix_dst_len);
 		}
 		else {
-			printk("MAP66: Unsupported --" IP6T_MAP66_DST_TO " prefix length /%d\n", 16 * info->pfix_dst_len);
+			printk("MAP66: Unsupported --" IP6T_MAP66_DST_TO " prefix "
+				"length /%d\n", 16 * info->pfix_dst_len);
 		}
 		return false;
 	}
@@ -275,10 +256,12 @@ static bool MAP66_tg6_check(
 	   (0 != (IP6T_MAP66_OPT_CSUM & info->mapflags) ? 8 : 7) < info->pfix_src_len))
 	{
 		if (8 == info->pfix_src_len) {
-			printk("MAP66: --" IP6T_MAP66_SRC_TO " prefix length /%d only possible with --csum\n", 16 * info->pfix_src_len);
+			printk("MAP66: --" IP6T_MAP66_SRC_TO " prefix length /%d only "
+				"possible with --csum\n", 16 * info->pfix_src_len);
 		}
 		else {
-			printk("MAP66: Unsupported --" IP6T_MAP66_SRC_TO " prefix length /%d\n", 16 * info->pfix_src_len);
+			printk("MAP66: Unsupported --" IP6T_MAP66_SRC_TO " prefix "
+				"length /%d\n", 16 * info->pfix_src_len);
 		}
 		return false;
 	}