X-Git-Url: http://git.sameswireless.fr/l2tpns.git/blobdiff_plain/786a8c4546c4a28f21d8995567e6f8f28f2eb053..b3f40f41f7de7a383c6f1170e546d0b09cc57338:/ipv6_u.c

diff --git a/ipv6_u.c b/ipv6_u.c
new file mode 100644
index 0000000..3c8ff12
--- /dev/null
+++ b/ipv6_u.c
@@ -0,0 +1,48 @@
+/*
+ * Fernando ALVES 2014
+ * GPL licenced
+ */
+
+#include <arpa/inet.h>
+
+#include "ipv6_u.h"
+
+uint16_t ipv6_checksum(struct ipv6_pseudo_hdr *p_pshdr, uint8_t *buff, int lenbuff)
+{
+	uint32_t sum = 0;
+	uint16_t *ptrw = (uint16_t *) p_pshdr;
+	uint16_t word16;
+	int i;
+
+	// Size pseudo header 40 byte (20 word)
+	for (i = 0; i < (sizeof(*p_pshdr)/2); i++)
+	{
+		word16 = ntohs(*((uint16_t *)ptrw));
+		sum += word16;
+		++ptrw;
+	}
+
+	ptrw = (uint16_t *) buff;
+	while (lenbuff > 1)
+	{
+		word16 = ntohs(*((uint16_t *) ptrw));
+		sum += word16;
+		++ptrw;
+		lenbuff -= 2;
+	}
+
+	if (lenbuff > 0)
+	{
+		word16 = ntohs(*((uint8_t *) ptrw));
+		sum += word16;
+	}
+
+	// take only 16 bits out of the 32 bit sum and add up the carries
+	while (sum >> 16)
+		sum = (sum & 0xFFFF) + (sum >> 16);
+
+	// one's complement the result
+	sum = ~sum;
+
+	return htons((uint16_t) sum);
+}