From b21154a9264baf559cfb5762d635828dd5164abb Mon Sep 17 00:00:00 2001
From: Matias Fontanini <matias.fontanini@gmail.com>
Date: Sun, 10 Jan 2016 16:31:48 -0800
Subject: [PATCH] Fix sequence number addition/subtraction when wrapping around

Fixes #115
---
 src/tcp_stream.cpp | 15 +++------------
 1 file changed, 3 insertions(+), 12 deletions(-)

diff --git a/src/tcp_stream.cpp b/src/tcp_stream.cpp
index 40a0d2e..c1895c6 100644
--- a/src/tcp_stream.cpp
+++ b/src/tcp_stream.cpp
@@ -38,24 +38,15 @@ namespace Tins {
 
 // As defined by RFC 1982 - 2 ^ (SERIAL_BITS - 1)
 static const uint32_t seq_number_diff = 2147483648U;
-// As defined by RFC 1982 - 2 ^ (SERIAL_BITS)
-static const uint32_t addition_modulo = numeric_limits<uint32_t>::max();
 
-// Sequence number add as defined by RFC 1982
+// Adds sequence numbers
 uint32_t add_sequence_numbers(uint32_t seq1, uint32_t seq2) {
-    return (static_cast<uint64_t>(seq1) + seq2) % addition_modulo;
+    return seq1 + seq2;
 }
 
 // Subtract sequence numbers
 uint32_t subtract_sequence_numbers(uint32_t seq1, uint32_t seq2) {
-    if (seq1 > seq2) {
-        return seq1 - seq2;
-    }
-    else  {
-        // the numbers between seq2 and the maximum sequence number(including seq1)
-        // + the numbers between 0 and seq1
-        return (numeric_limits<uint32_t>::max() - seq2) + seq1 + 1;
-    }
+    return seq1 - seq2;
 }
 
 // Compares sequence numbers as defined by RFC 1982.