1 files changed, 78 insertions, 0 deletions
diff --git a/src/extra/checksum.c b/src/extra/checksum.c
new file mode 100644
index 0000000..d0c4167
--- /dev/null
+++ b/src/extra/checksum.c
@@ -0,0 +1,78 @@
+/*
+ * (C) 2012 by Pablo Neira Ayuso <pablo@netfilter.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This code has been sponsored by Vyatta Inc. <http://www.vyatta.com>
+ */
+
+#include <stdio.h>
+#include <arpa/inet.h>
+#include <netinet/ip.h>
+#include <netinet/ip6.h>
+#include <netinet/tcp.h>
+
+#include <libnetfilter_queue/libnetfilter_queue.h>
+
+#include "internal.h"
+
+uint16_t checksum(uint32_t sum, uint16_t *buf, int size)
+{
+	while (size > 1) {
+		sum += *buf++;
+		size -= sizeof(uint16_t);
+	}
+	if (size)
+		sum += *(uint8_t *)buf;
+
+	sum = (sum >> 16) + (sum & 0xffff);
+	sum += (sum >>16);
+
+	return (uint16_t)(~sum);
+}
+
+uint16_t checksum_tcpudp_ipv4(struct iphdr *iph)
+{
+	uint32_t sum = 0;
+	uint32_t iph_len = iph->ihl*4;
+	uint32_t len = ntohs(iph->tot_len) - iph_len;
+	uint8_t *payload = (uint8_t *)iph + iph_len;
+
+	sum += (iph->saddr >> 16) & 0xFFFF;
+	sum += (iph->saddr) & 0xFFFF;
+	sum += (iph->daddr >> 16) & 0xFFFF;
+	sum += (iph->daddr) & 0xFFFF;
+	sum += htons(IPPROTO_TCP);
+	sum += htons(len);
+
+	return checksum(sum, (uint16_t *)payload, len);
+}
+
+uint16_t checksum_tcpudp_ipv6(struct ip6_hdr *ip6h, void *transport_hdr)
+{
+	uint32_t sum = 0;
+	uint32_t hdr_len = (uint32_t *)transport_hdr - (uint32_t *)ip6h;
+	uint32_t len = ip6h->ip6_plen - hdr_len;
+	uint8_t *payload = (uint8_t *)ip6h + hdr_len;
+	int i;
+
+	for (i=0; i<8; i++) {
+		sum += (ip6h->ip6_src.s6_addr16[i] >> 16) & 0xFFFF;
+		sum += (ip6h->ip6_src.s6_addr16[i]) & 0xFFFF;
+	}
+	for (i=0; i<8; i++) {
+		sum += (ip6h->ip6_dst.s6_addr16[i] >> 16) & 0xFFFF;
+		sum += (ip6h->ip6_dst.s6_addr16[i]) & 0xFFFF;
+	}
+	sum += htons(IPPROTO_TCP);
+	sum += htons(ip6h->ip6_plen);
+
+	return checksum(sum, (uint16_t *)payload, len);
+}
+
+/**
+ * @}
+ */