[pisa-src] r1653 - in trunk/libpisa: checksum.h nat.c
- From: Thomas Jansen <mithi@xxxxxxxxx>
- To: pisa-src@xxxxxxxxxxxxx
- Date: Thu, 12 Nov 2009 13:08:21 +0100
Author: tjansen
Date: Thu Nov 12 13:08:21 2009
New Revision: 1653
Log:
Merged checksum.h into nat.c
checksum.h was only used by nat.c.
Deleted:
trunk/libpisa/checksum.h
Modified:
trunk/libpisa/nat.c
Modified: trunk/libpisa/nat.c
==============================================================================
--- trunk/libpisa/nat.c Thu Nov 12 12:59:29 2009 (r1652)
+++ trunk/libpisa/nat.c Thu Nov 12 13:08:21 2009 (r1653)
@@ -16,10 +16,47 @@
#include <netinet/udp.h>
#include <netinet/tcp.h>
-#include "checksum.h"
#include "nat.h"
/**
+ * Fold a 32-bit checksum into a 16-bit checksum.
+ * @param checksum checksum that will be folded
+ * @return folded checksum (16 bit)
+ */
+static inline uint16_t pisa_csum_fold(uint32_t checksum)
+{
+ while (checksum >> 16)
+ checksum = (checksum & 0xffff) + (checksum >> 16);
+ return checksum;
+}
+
+/**
+ * Unfold a 16-bit checksum into a 32-bit checksum.
+ * @param checksum checksum that will be unfolded
+ * @return unfolded checksum (32 bit)
+ */
+static inline uint32_t pisa_csum_unfold(uint16_t checksum)
+{
+ return (uint32_t) checksum;
+}
+
+/**
+ * Replace 4 bytes in a checksum.
+ * @param addr pointer to the current checksum. Will be updated to the new
+ * checksum when the functions returns.
+ * @param before 4 bytes that were used to calculate the old checksum and
+ * should be replaced.
+ * @param after 4 bytes that will become part of the new checksum.
+ */
+static inline void pisa_csum_replace4(uint16_t *checksum, uint32_t before,
uint32_t after)
+{
+ uint32_t checksum_new = pisa_csum_unfold(~*checksum);
+ checksum_new += ((~before) & 0xffff) + ((~before) >> 16);
+ checksum_new += (after & 0xffff) + (after >> 16);
+ *checksum = ~pisa_csum_fold(checksum_new);
+}
+
+/**
* Apply NAT mapping to a given IPv4 packet.
* @param ip pointer to the IPv4 header of the packet
* @param before pointer to the old IPv4 address in the packet. Can be
Other related posts:
- » [pisa-src] r1653 - in trunk/libpisa: checksum.h nat.c - Thomas Jansen
