From 7eab0b51c9d48395d45d3230ddd0b44b94aefa97 Mon Sep 17 00:00:00 2001
From: Tom Henderson <tomh@tomh.org>
Date: Sat, 3 Jun 2017 08:10:44 -0700
Subject: [PATCH] point-to-point: (fixes #2556) Avoid modification of
 transmitted packets

Packets sent to channel may later be modified by calling device.  Possible
solutions are to copy before or after sending the packet to the channel.
Adopted solution similar to YansWifiChannel; a Ptr<const Packet> is instead
passed to the channel object, and channel object is responsible for copy.
---
 src/point-to-point/model/point-to-point-channel.cc        | 4 ++--
 src/point-to-point/model/point-to-point-channel.h         | 2 +-
 src/point-to-point/model/point-to-point-remote-channel.cc | 4 ++--
 src/point-to-point/model/point-to-point-remote-channel.h  | 2 +-
 4 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/src/point-to-point/model/point-to-point-channel.cc b/src/point-to-point/model/point-to-point-channel.cc
index d59cbd17b..77dd626d5 100644
--- a/src/point-to-point/model/point-to-point-channel.cc
+++ b/src/point-to-point/model/point-to-point-channel.cc
@@ -85,7 +85,7 @@ PointToPointChannel::Attach (Ptr<PointToPointNetDevice> device)
 
 bool
 PointToPointChannel::TransmitStart (
-  Ptr<Packet> p,
+  Ptr<const Packet> p,
   Ptr<PointToPointNetDevice> src,
   Time txTime)
 {
@@ -99,7 +99,7 @@ PointToPointChannel::TransmitStart (
 
   Simulator::ScheduleWithContext (m_link[wire].m_dst->GetNode ()->GetId (),
                                   txTime + m_delay, &PointToPointNetDevice::Receive,
-                                  m_link[wire].m_dst, p);
+                                  m_link[wire].m_dst, p->Copy ());
 
   // Call the tx anim callback on the net device
   m_txrxPointToPoint (p, src, m_link[wire].m_dst, txTime, txTime + m_delay);
diff --git a/src/point-to-point/model/point-to-point-channel.h b/src/point-to-point/model/point-to-point-channel.h
index e53bfe141..732bfca94 100644
--- a/src/point-to-point/model/point-to-point-channel.h
+++ b/src/point-to-point/model/point-to-point-channel.h
@@ -78,7 +78,7 @@ public:
    * \param txTime Transmit time to apply
    * \returns true if successful (currently always true)
    */
-  virtual bool TransmitStart (Ptr<Packet> p, Ptr<PointToPointNetDevice> src, Time txTime);
+  virtual bool TransmitStart (Ptr<const Packet> p, Ptr<PointToPointNetDevice> src, Time txTime);
 
   /**
    * \brief Get number of devices on this channel
diff --git a/src/point-to-point/model/point-to-point-remote-channel.cc b/src/point-to-point/model/point-to-point-remote-channel.cc
index 40f98cecb..46fe81be3 100644
--- a/src/point-to-point/model/point-to-point-remote-channel.cc
+++ b/src/point-to-point/model/point-to-point-remote-channel.cc
@@ -55,7 +55,7 @@ PointToPointRemoteChannel::~PointToPointRemoteChannel ()
 
 bool
 PointToPointRemoteChannel::TransmitStart (
-  Ptr<Packet> p,
+  Ptr<const Packet> p,
   Ptr<PointToPointNetDevice> src,
   Time txTime)
 {
@@ -70,7 +70,7 @@ PointToPointRemoteChannel::TransmitStart (
 #ifdef NS3_MPI
   // Calculate the rxTime (absolute)
   Time rxTime = Simulator::Now () + txTime + GetDelay ();
-  MpiInterface::SendPacket (p, rxTime, dst->GetNode ()->GetId (), dst->GetIfIndex ());
+  MpiInterface::SendPacket (p->Copy (), rxTime, dst->GetNode ()->GetId (), dst->GetIfIndex ());
 #else
   NS_FATAL_ERROR ("Can't use distributed simulator without MPI compiled in");
 #endif
diff --git a/src/point-to-point/model/point-to-point-remote-channel.h b/src/point-to-point/model/point-to-point-remote-channel.h
index fd1a9a8a5..f10b2df91 100644
--- a/src/point-to-point/model/point-to-point-remote-channel.h
+++ b/src/point-to-point/model/point-to-point-remote-channel.h
@@ -66,7 +66,7 @@ public:
    * \param txTime Transmit time to apply
    * \returns true if successful (currently always true)
    */
-  virtual bool TransmitStart (Ptr<Packet> p, Ptr<PointToPointNetDevice> src,
+  virtual bool TransmitStart (Ptr<const Packet> p, Ptr<PointToPointNetDevice> src,
                               Time txTime);
 };