From aa4c559a3a7c52cdef8ca52f91e3e557190adee4 Mon Sep 17 00:00:00 2001
From: Baptiste Wicht <baptiste.wicht@gmail.com>
Date: Mon, 26 Sep 2016 11:44:57 +0200
Subject: [PATCH] Safer checksum

---
 kernel/src/net/udp_layer.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/src/net/udp_layer.cpp b/kernel/src/net/udp_layer.cpp
index ca7fb760..cf6be0fe 100644
--- a/kernel/src/net/udp_layer.cpp
+++ b/kernel/src/net/udp_layer.cpp
@@ -36,14 +36,14 @@ network::connection_handler<udp_connection> connections;
 
 void compute_checksum(network::ethernet::packet& packet){
     auto* ip_header = reinterpret_cast<network::ip::header*>(packet.payload + packet.tag(1));
-    auto* udp_header = reinterpret_cast<network::udp::header*>(packet.payload + packet.index);
+    auto* udp_header = reinterpret_cast<network::udp::header*>(packet.payload + packet.tag(2));
 
     udp_header->checksum = 0;
 
     auto length = switch_endian_16(udp_header->length);
 
     // Accumulate the Payload
-    auto sum = network::checksum_add_bytes(packet.payload + packet.index, length);
+    auto sum = network::checksum_add_bytes(packet.payload + packet.tag(2), length);
 
     // Accumulate the IP addresses
     sum += network::checksum_add_bytes(&ip_header->source_ip, 8);