From eb218ff80b8f6b88ed74249a9c6fecb860454110 Mon Sep 17 00:00:00 2001
From: Tobias Brunner <tobias@strongswan.org>
Date: Wed, 22 Oct 2014 19:41:40 +0200
Subject: [PATCH] chunk: Fix internet checksum calculation on big-endian
 systems

ntohs() might be defined as noop (#define ntohs(x) (x)) so we have
to manually shorten the negated value (gets promoted to an int).

Fixes #747.
---
 src/libstrongswan/utils/chunk.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libstrongswan/utils/chunk.c b/src/libstrongswan/utils/chunk.c
index 4b24b37c2..c4471be70 100644
--- a/src/libstrongswan/utils/chunk.c
+++ b/src/libstrongswan/utils/chunk.c
@@ -992,7 +992,7 @@ u_int32_t chunk_hash_static(chunk_t chunk)
  */
 u_int16_t chunk_internet_checksum_inc(chunk_t data, u_int16_t checksum)
 {
-	u_int32_t sum = ntohs(~checksum);
+	u_int32_t sum = ntohs((u_int16_t)~checksum);
 
 	while (data.len > 1)
 	{