From d5f9dc201b9d74ba86ffce24694c5190d57f32f0 Mon Sep 17 00:00:00 2001
From: Stefano Avallone <stavallo@unina.it>
Date: Sun, 26 Nov 2023 18:59:37 +0100
Subject: [PATCH] internet: Set the TOS for ICMP Echo Requests/Replies

---
 src/internet-apps/model/ping.cc          | 11 +++++++++--
 src/internet-apps/model/ping.h           |  2 ++
 src/internet/model/icmpv4-l4-protocol.cc | 10 +++++++---
 src/internet/model/icmpv4-l4-protocol.h  |  4 +++-
 4 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/src/internet-apps/model/ping.cc b/src/internet-apps/model/ping.cc
index 96af7c094..05cb2a069 100644
--- a/src/internet-apps/model/ping.cc
+++ b/src/internet-apps/model/ping.cc
@@ -103,6 +103,12 @@ Ping::GetTypeId()
                           TimeValue(Seconds(1)),
                           MakeTimeAccessor(&Ping::m_timeout),
                           MakeTimeChecker())
+            .AddAttribute("Tos",
+                          "The Type of Service used to send the ICMP Echo Requests. "
+                          "All 8 bits of the TOS byte are set (including ECN bits).",
+                          UintegerValue(0),
+                          MakeUintegerAccessor(&Ping::m_tos),
+                          MakeUintegerChecker<uint8_t>())
             .AddTraceSource("Tx",
                             "The sequence number and ICMP echo response packet.",
                             MakeTraceSourceAccessor(&Ping::m_txTrace),
@@ -455,8 +461,9 @@ Ping::Send()
             header.EnableChecksum();
         }
         p->AddHeader(header);
-        returnValue =
-            m_socket->SendTo(p, 0, InetSocketAddress(Ipv4Address::ConvertFrom(m_destination), 0));
+        auto dest = InetSocketAddress(Ipv4Address::ConvertFrom(m_destination), 0);
+        dest.SetTos(m_tos);
+        returnValue = m_socket->SendTo(p, 0, dest);
     }
     else
     {
diff --git a/src/internet-apps/model/ping.h b/src/internet-apps/model/ping.h
index aaf80ea72..e6d23cf36 100644
--- a/src/internet-apps/model/ping.h
+++ b/src/internet-apps/model/ping.h
@@ -213,6 +213,8 @@ class Ping : public Application
     uint32_t m_size{56};
     /// The socket we send packets from
     Ptr<Socket> m_socket;
+    /// The Type of Service carried by ICMP ECHOs
+    uint8_t m_tos;
     /// ICMP ECHO sequence number
     uint16_t m_seq{0};
     /// Callbacks for tracing the packet Tx events
diff --git a/src/internet/model/icmpv4-l4-protocol.cc b/src/internet/model/icmpv4-l4-protocol.cc
index db64443a1..8f823b795 100644
--- a/src/internet/model/icmpv4-l4-protocol.cc
+++ b/src/internet/model/icmpv4-l4-protocol.cc
@@ -222,14 +222,18 @@ void
 Icmpv4L4Protocol::HandleEcho(Ptr<Packet> p,
                              Icmpv4Header header,
                              Ipv4Address source,
-                             Ipv4Address destination)
+                             Ipv4Address destination,
+                             uint8_t tos)
 {
-    NS_LOG_FUNCTION(this << p << header << source << destination);
+    NS_LOG_FUNCTION(this << p << header << source << destination << tos);
 
     Ptr<Packet> reply = Create<Packet>();
     Icmpv4Echo echo;
     p->RemoveHeader(echo);
     reply->AddHeader(echo);
+    SocketIpTosTag ipTosTag;
+    ipTosTag.SetTos(tos);
+    reply->ReplacePacketTag(ipTosTag);
     SendMessage(reply, destination, source, Icmpv4Header::ICMPV4_ECHO_REPLY, 0, nullptr);
 }
 
@@ -327,7 +331,7 @@ Icmpv4L4Protocol::Receive(Ptr<Packet> p,
                 }
             }
         }
-        HandleEcho(p, icmp, header.GetSource(), dst);
+        HandleEcho(p, icmp, header.GetSource(), dst, header.GetTos());
         break;
     }
     case Icmpv4Header::ICMPV4_DEST_UNREACH:
diff --git a/src/internet/model/icmpv4-l4-protocol.h b/src/internet/model/icmpv4-l4-protocol.h
index 18a3439f6..6f558bb0b 100644
--- a/src/internet/model/icmpv4-l4-protocol.h
+++ b/src/internet/model/icmpv4-l4-protocol.h
@@ -143,11 +143,13 @@ class Icmpv4L4Protocol : public IpL4Protocol
      * \param header the IP header
      * \param source the source address
      * \param destination the destination address
+     * \param tos the type of service
      */
     void HandleEcho(Ptr<Packet> p,
                     Icmpv4Header header,
                     Ipv4Address source,
-                    Ipv4Address destination);
+                    Ipv4Address destination,
+                    uint8_t tos);
     /**
      * \brief Handles an incoming ICMP Destination Unreachable packet
      * \param p the packet