From f004db89cf2b83b8d63ad027efbeb72f985f5f6b Mon Sep 17 00:00:00 2001
From: Asias He <asias@cloudius-systems.com>
Date: Thu, 15 Jan 2015 03:55:49 +0200
Subject: [PATCH] tcp: Make tcp_option get_size and fill more readable

---
 net/tcp.cc | 22 ++++++++++++++--------
 net/tcp.hh | 18 +++++++++---------
 2 files changed, 23 insertions(+), 17 deletions(-)

diff --git a/net/tcp.cc b/net/tcp.cc
index 9b4a7e15e5..3bd7bf858c 100644
--- a/net/tcp.cc
+++ b/net/tcp.cc
@@ -59,16 +59,18 @@ uint8_t tcp_option::fill(tcp_hdr* th, uint8_t options_size) {
     auto hdr = reinterpret_cast<uint8_t*>(th);
     auto off = hdr + sizeof(tcp_hdr);
     uint8_t size = 0;
+    bool syn_on = th->f_syn;
+    bool ack_on = th->f_ack;
 
-    if (th->f_syn) {
-        if (_mss_received || !th->f_ack) {
+    if (syn_on) {
+        if (_mss_received || !ack_on) {
             auto mss = new (off) tcp_option::mss;
             mss->mss = _local_mss;
             off += mss->len;
             size += mss->len;
             *mss = hton(*mss);
         }
-        if (_win_scale_received || !th->f_ack) {
+        if (_win_scale_received || !ack_on) {
             auto win_scale = new (off) tcp_option::win_scale;
             win_scale->shift = _local_win_scale;
             off += win_scale->len;
@@ -91,12 +93,16 @@ uint8_t tcp_option::fill(tcp_hdr* th, uint8_t options_size) {
     return size;
 }
 
-uint8_t tcp_option::get_size(bool foreign_syn_received) {
+uint8_t tcp_option::get_size(bool syn_on, bool ack_on) {
     uint8_t size = 0;
-    if (_mss_received || !foreign_syn_received)
-        size += option_len::mss;
-    if (_win_scale_received || !foreign_syn_received)
-        size += option_len::win_scale;
+    if (syn_on) {
+        if (_mss_received || !ack_on) {
+            size += option_len::mss;
+        }
+        if (_win_scale_received || !ack_on) {
+            size += option_len::win_scale;
+        }
+    }
     if (size > 0) {
         size += option_len::eol;
         // Insert NOP option to align on 32-bit
diff --git a/net/tcp.hh b/net/tcp.hh
index e886642a16..e3e30dfb49 100644
--- a/net/tcp.hh
+++ b/net/tcp.hh
@@ -68,7 +68,7 @@ struct tcp_option {
 
     void parse(uint8_t* beg, uint8_t* end);
     uint8_t fill(tcp_hdr* th, uint8_t option_size);
-    uint8_t get_size(bool foreign_syn_received);
+    uint8_t get_size(bool syn_on, bool ack_on);
 
     // For option negotiattion
     bool _mss_received = false;
@@ -889,21 +889,21 @@ void tcp<InetTraits>::tcb::output_one() {
         return;
     }
 
-    uint8_t options_size = 0;
     packet p = get_transmit_packet();
     uint16_t len = p.len();
+    bool syn_on = !_local_syn_acked;
+    bool ack_on = _foreign_syn_received;
 
-    if (!_local_syn_acked) {
-        options_size = _option.get_size(_foreign_syn_received);
-    }
+    auto options_size = _option.get_size(syn_on, ack_on);
     auto th = p.prepend_header<tcp_hdr>(options_size);
+
     th->src_port = _local_port;
     th->dst_port = _foreign_port;
 
-    th->f_syn = !_local_syn_acked;
-    _local_syn_sent |= th->f_syn;
-    th->f_ack = _foreign_syn_received;
-    if (th->f_ack) {
+    th->f_syn = syn_on;
+    _local_syn_sent |= syn_on;
+    th->f_ack = ack_on;
+    if (ack_on) {
         clear_delayed_ack();
     }
     th->f_urg = false;