From bd7b0115c11870d3a97b8c0ed25498b6eed2aa8f Mon Sep 17 00:00:00 2001
From: Alin Nastac <alin.nastac@gmail.com>
Date: Tue, 8 Oct 2019 12:54:11 +0200
Subject: checksum: Fix TCP/UDP checksum computation on big endian arches

On big endian arches UDP/TCP checksum is incorrectly computed when
payload length is odd.

Signed-off-by: Alin Nastac <alin.nastac@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 src/extra/checksum.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/src/extra/checksum.c b/src/extra/checksum.c
index 4d52a99..42389aa 100644
--- a/src/extra/checksum.c
+++ b/src/extra/checksum.c
@@ -11,6 +11,7 @@
 
 #include <stdio.h>
 #include <stdbool.h>
+#include <endian.h>
 #include <arpa/inet.h>
 #include <netinet/ip.h>
 #include <netinet/ip6.h>
@@ -26,8 +27,13 @@ uint16_t nfq_checksum(uint32_t sum, uint16_t *buf, int size)
 		sum += *buf++;
 		size -= sizeof(uint16_t);
 	}
-	if (size)
-		sum += *(uint8_t *)buf;
+	if (size) {
+#if __BYTE_ORDER == __BIG_ENDIAN
+		sum += (uint16_t)*(uint8_t *)buf << 8;
+#else
+		sum += (uint16_t)*(uint8_t *)buf;
+#endif
+	}
 
 	sum = (sum >> 16) + (sum & 0xffff);
 	sum += (sum >>16);
-- 
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