From 27a73b89f087fb13cecc21784551a89e9827b101 Mon Sep 17 00:00:00 2001
From: Johannes Schlatow <schlatow@ida.ing.tu-bs.de>
Date: Fri, 18 Mar 2016 19:41:00 +0100
Subject: [PATCH] net: write accessors for Ipv4_packet

Also adds header-checksum calculation function.

Fixes #1915
---
 repos/os/include/net/ipv4.h  | 16 ++++++++++++++++
 repos/os/src/lib/net/ipv4.cc | 15 +++++++++++++++
 2 files changed, 31 insertions(+)

diff --git a/repos/os/include/net/ipv4.h b/repos/os/include/net/ipv4.h
index 87ff71821f..a735f05d17 100644
--- a/repos/os/include/net/ipv4.h
+++ b/repos/os/include/net/ipv4.h
@@ -60,6 +60,8 @@ class Net::Ipv4_packet
 
 		static Ipv4_address ip_from_string(const char *ip);
 
+		static Genode::uint16_t calculate_checksum(Ipv4_packet const &packet);
+
 	private:
 
 		/************************
@@ -161,6 +163,20 @@ class Net::Ipv4_packet
 		template <typename T> T *       data()         { return (T *)(_data); }
 		template <typename T> T const * data()   const { return (T const *)(_data); }
 
+		/********************************
+		 ** IPv4 field write-accessors **
+		 ********************************/
+
+		void version(Genode::size_t version)    { _version = version; }
+		void header_length(Genode::size_t len)  { _header_length = len; }
+
+		void total_length(Genode::uint16_t len) { _total_length = host_to_big_endian(len); }
+		void time_to_live(Genode::uint8_t ttl)  { _time_to_live = ttl; }
+
+		void checksum(Genode::uint16_t checksum) { _header_checksum = host_to_big_endian(checksum); }
+
+		void dst(Ipv4_address ip) { ip.copy(&_dst_addr); }
+		void src(Ipv4_address ip) { ip.copy(&_src_addr); }
 
 		/***************
 		 ** Operators **
diff --git a/repos/os/src/lib/net/ipv4.cc b/repos/os/src/lib/net/ipv4.cc
index 092ace537f..fdb98a897e 100644
--- a/repos/os/src/lib/net/ipv4.cc
+++ b/repos/os/src/lib/net/ipv4.cc
@@ -62,6 +62,21 @@ Ipv4_packet::Ipv4_address Ipv4_packet::ip_from_string(const char *ip)
 	return ip_addr;
 }
 
+Genode::uint16_t Ipv4_packet::calculate_checksum(Ipv4_packet const &packet)
+{
+	Genode::uint16_t const *data = packet.header<Genode::uint16_t>();
+	Genode::uint32_t const sum = host_to_big_endian(data[0])
+	                           + host_to_big_endian(data[1])
+	                           + host_to_big_endian(data[2])
+	                           + host_to_big_endian(data[3])
+	                           + host_to_big_endian(data[4])
+	                           + host_to_big_endian(data[6])
+	                           + host_to_big_endian(data[7])
+	                           + host_to_big_endian(data[8])
+	                           + host_to_big_endian(data[9]);
+	return ~((0xFFFF & sum) + (sum >> 16));
+}
+
 
 const Ipv4_packet::Ipv4_address Ipv4_packet::CURRENT((Genode::uint8_t)0x00);
 const Ipv4_packet::Ipv4_address Ipv4_packet::BROADCAST((Genode::uint8_t)0xFF);