From 1c9d2da4cd0fa50842bf3bcf2923fb2df4b86259 Mon Sep 17 00:00:00 2001
From: Jens Ahrensfeld <jens@jayfield.org>
Date: Fri, 26 Nov 2021 14:43:41 +0000
Subject: [PATCH] - fixed checksum calculation

git-svn-id: http://moon:8086/svn/mips@225 a8ebac50-d88d-4704-bea3-6648445a41b3
---
 src/common/network/ipv4.c | 18 +++++++++---------
 src/common/network/udp.c  |  1 +
 2 files changed, 10 insertions(+), 9 deletions(-)

diff --git a/src/common/network/ipv4.c b/src/common/network/ipv4.c
index 141f351..5c9a014 100644
--- a/src/common/network/ipv4.c
+++ b/src/common/network/ipv4.c
@@ -41,26 +41,26 @@ uint8_t *IPV4_create(packet_t *pPacket, uint16_t proto, uint16_t len, uint8_t *i
 }
 
 // -------------------------------------------------------------------------
+uint16_t sumup(uint16_t sum, uint16_t value)
+{
+	uint32_t sum32 = (uint32_t)sum + (uint32_t)value;
+	uint16_t result = (uint16_t)(sum32 >> 16) + (0xFFFF & sum32);
+	return result;
+}
+
 uint16_t IPv4ChkSum(void *pBuf, uint16_t acc, uint16_t len)
 {
 	uint16_t *pBuf16 = (uint16_t*)pBuf;
 	while(len > 1)
 	{
-		acc += *pBuf16;
-		if(acc < *pBuf16)
-			acc++;
-
-	    ++pBuf16;
+		acc = sumup(acc, *(pBuf16++));
 		len -= 2;
 	}
 
 	/* add up any odd byte */
 	if(len == 1)
 	{
-		acc += htons(((uint16_t)(*(uint8_t *)pBuf16)) << 8);
-		if(acc < htons(((uint16_t)(*(uint8_t *)pBuf16)) << 8))
-			acc++;
+		acc = sumup(acc, htons(((uint16_t)(*(uint8_t *)pBuf16)) << 8));
 	}
 	return acc;
 }
-
diff --git a/src/common/network/udp.c b/src/common/network/udp.c
index 78cb79c..2c955af 100644
--- a/src/common/network/udp.c
+++ b/src/common/network/udp.c
@@ -29,6 +29,7 @@ uint8_t *UDP_create(packet_t *pPacket, uint8_t *inet_addr_src, uint16_t port_src
 	// Fill pseudo header
 	memcpy(&pseudo_hdr.inet_addr_src, inet_addr_src, 4);
 	memcpy(&pseudo_hdr.inet_addr_dst, inet_addr_dst, 4);
+	pseudo_hdr.zero = 0;
 	pseudo_hdr.proto = IP_TYPE_UDP;
 	pseudo_hdr.len = len + sizeof(UDP);