To implement Simple Mail Transfer Protocol (SMTP) in ns3, we have to create modules for SMTP client and server applications, define the protocol logic, and integrate it with ns3’s existing network simulation framework.
Here is a complete guide to implement SMTP in ns3.
Prerequisites
- ns3 installation :
make sure that ns3 is installed on your computer.
- C++ Programming :
You should have knowledge in C++.
- Understanding of ns3 :
You should be familiar with ns3 modules and basic simulation scripts.
Steps to implement SMTP in ns3
- Set up your environment
Make sure that ns3 is installed in the computer. If not, install it from the official ns3 website.
- Create a new SMTP module
Go to the src directory in ns3 and create a new directory for your SMTP module.
cd ns-3.XX/src
mkdir smtp
cd smtp
mkdir model helper test
- Define SMTP classes and header files
In the model directory, create header and implementation files for SMTP.
smtp-server.h
#ifndef SMTP_SERVER_H
#define SMTP_SERVER_H
#include “ns3/application.h”
#include “ns3/address.h”
#include “ns3/ptr.h”
#include “ns3/socket.h”
#include “ns3/traced-callback.h”
namespace ns3 {
class SmtpServer : public Application {
public:
static TypeId GetTypeId (void);
SmtpServer ();
virtual ~SmtpServer ();
protected:
virtual void StartApplication (void);
virtual void StopApplication (void);
private:
void HandleRead (Ptr<Socket> socket);
void SendResponse (Ptr<Socket> socket, const std::string &response);
Ptr<Socket> m_socket;
Address m_local;
};
} // namespace ns3
#endif // SMTP_SERVER_H
smtp-server.cc
#include “smtp-server.h”
#include “ns3/log.h”
#include “ns3/simulator.h”
#include “ns3/inet-socket-address.h”
#include “ns3/uinteger.h”
namespace ns3 {
NS_LOG_COMPONENT_DEFINE (“SmtpServer”);
NS_OBJECT_ENSURE_REGISTERED (SmtpServer);
TypeId SmtpServer::GetTypeId (void) {
static TypeId tid = TypeId (“ns3::SmtpServer”)
.SetParent<Application> ()
.SetGroupName (“Applications”)
.AddConstructor<SmtpServer> ()
.AddAttribute (“Local”, “The Address on which to Bind the rx socket.”,
AddressValue (),
MakeAddressAccessor (&SmtpServer::m_local),
MakeAddressChecker ());
return tid;
}
SmtpServer::SmtpServer () {
NS_LOG_FUNCTION (this);
}
SmtpServer::~SmtpServer () {
NS_LOG_FUNCTION (this);
}
void SmtpServer::StartApplication () {
NS_LOG_FUNCTION (this);
if (m_socket == 0) {
m_socket = Socket::CreateSocket (GetNode (), TcpSocketFactory::GetTypeId ());
m_socket->Bind (m_local);
m_socket->Listen ();
m_socket->SetRecvCallback (MakeCallback (&SmtpServer::HandleRead, this));
}
}
void SmtpServer::StopApplication () {
NS_LOG_FUNCTION (this);
if (m_socket) {
m_socket->Close ();
m_socket->SetRecvCallback (MakeNullCallback<void, Ptr<Socket> > ());
}
}
void SmtpServer::HandleRead (Ptr<Socket> socket) {
NS_LOG_FUNCTION (this << socket);
Ptr<Packet> packet;
Address from;
while ((packet = socket->RecvFrom (from))) {
NS_LOG_INFO (“Received request from ” << InetSocketAddress::ConvertFrom (from).GetIpv4 ());
// Process SMTP commands and send responses
std::string response = “220 ns-3 SMTP Server Ready\r\n”;
SendResponse (socket, response);
}
}
void SmtpServer::SendResponse (Ptr<Socket> socket, const std::string &response) {
NS_LOG_FUNCTION (this << socket << response);
Ptr<Packet> packet = Create<Packet> ((const uint8_t *)response.c_str (), response.size ());
socket->Send (packet);
NS_LOG_INFO (“Sent response: ” << response);
}
} // namespace ns3
smtp-client.h
#ifndef SMTP_CLIENT_H
#define SMTP_CLIENT_H
#include “ns3/application.h”
#include “ns3/address.h”
#include “ns3/ptr.h”
#include “ns3/socket.h”
#include “ns3/traced-callback.h”
namespace ns3 {
class SmtpClient : public Application {
public:
static TypeId GetTypeId (void);
SmtpClient ();
virtual ~SmtpClient ();
protected:
virtual void StartApplication (void);
virtual void StopApplication (void);
private:
void SendRequest ();
void HandleRead (Ptr<Socket> socket);
Ptr<Socket> m_socket;
Address m_peer;
EventId m_sendEvent;
};
} // namespace ns3
#endif // SMTP_CLIENT_H
smtp-client.cc
#include “smtp-client.h”
#include “ns3/log.h”
#include “ns3/simulator.h”
#include “ns3/inet-socket-address.h”
#include “ns3/uinteger.h”
namespace ns3 {
NS_LOG_COMPONENT_DEFINE (“SmtpClient”);
NS_OBJECT_ENSURE_REGISTERED (SmtpClient);
TypeId SmtpClient::GetTypeId (void) {
static TypeId tid = TypeId (“ns3::SmtpClient”)
.SetParent<Application> ()
.SetGroupName (“Applications”)
.AddConstructor<SmtpClient> ()
.AddAttribute (“Remote”, “The Address of the SMTP server.”,
AddressValue (),
MakeAddressAccessor (&SmtpClient::m_peer),
MakeAddressChecker ());
return tid;
}
SmtpClient::SmtpClient () {
NS_LOG_FUNCTION (this);
}
SmtpClient::~SmtpClient () {
NS_LOG_FUNCTION (this);
}
void SmtpClient::StartApplication () {
NS_LOG_FUNCTION (this);
if (m_socket == 0) {
m_socket = Socket::CreateSocket (GetNode (), TcpSocketFactory::GetTypeId ());
m_socket->Connect (m_peer);
m_socket->SetRecvCallback (MakeCallback (&SmtpClient::HandleRead, this));
m_sendEvent = Simulator::Schedule (Seconds (1.0), &SmtpClient::SendRequest, this);
}
}
void SmtpClient::StopApplication () {
NS_LOG_FUNCTION (this);
if (m_socket) {
m_socket->Close ();
}
Simulator::Cancel (m_sendEvent);
}
void SmtpClient::SendRequest () {
NS_LOG_FUNCTION (this);
std::string request = “HELO ns-3 client\r\n”;
Ptr<Packet> packet = Create<Packet> ((const uint8_t *)request.c_str (), request.size ());
m_socket->Send (packet);
NS_LOG_INFO (“Sent request to server: ” << request);
}
void SmtpClient::HandleRead (Ptr<Socket> socket) {
NS_LOG_FUNCTION (this << socket);
Ptr<Packet> packet;
Address from;
while ((packet = socket->RecvFrom (from))) {
uint8_t *buffer = new uint8_t[packet->GetSize ()];
packet->CopyData (buffer, packet->GetSize ());
std::string response = std::string ((char *)buffer, packet->GetSize ());
NS_LOG_INFO (“Received response from server: ” << response);
delete[] buffer;
}
}
} // namespace ns3
- Create SMTP helper class
To facilitate the use and to test SMTP, create helper classes.
smtp-helper.h
#ifndef SMTP_HELPER_H
#define SMTP_HELPER_H
#include “ns3/application-container.h”
#include “ns3/node-container.h”
#include “ns3/smtp-server.h”
#include “ns3/smtp-client.h”
namespace ns3 {
class SmtpServerHelper {
public:
SmtpServerHelper (Address address);
ApplicationContainer Install (NodeContainer c);
private:
Ptr<Application> InstallPriv (Ptr<Node> node);
Address m_address;
};
class SmtpClientHelper {
public:
SmtpClientHelper (Address address);
ApplicationContainer Install (NodeContainer c);
private:
Ptr<Application> InstallPriv (Ptr<Node> node);
Address m_address;
};
} // namespace ns3
#endif // SMTP_HELPER_H
smtp-helper.cc
#include “smtp-helper.h”
#include “ns3/uinteger.h”
#include “ns3/names.h”
namespace ns3 {
SmtpServerHelper::SmtpServerHelper (Address address)
: m_address (address) {
}
ApplicationContainer SmtpServerHelper::Install (NodeContainer c) {
ApplicationContainer apps;
for (NodeContainer::Iterator i = c.Begin (); i != c.End (); ++i) {
Ptr<Node> node = *i;
Ptr<Application> app = InstallPriv (node);
apps.Add (app);
}
return apps;
}
Ptr<Application> SmtpServerHelper::InstallPriv (Ptr<Node> node) {
Ptr<SmtpServer> server = CreateObject<SmtpServer> ();
server->SetAttribute (“Local”, AddressValue (m_address));
node->AddApplication (server);
return server;
}
SmtpClientHelper::SmtpClientHelper (Address address)
: m_address (address) {
}
ApplicationContainer SmtpClientHelper::Install (NodeContainer c) {
ApplicationContainer apps;
for (NodeContainer::Iterator i = c.Begin (); i != c.End (); ++i) {
Ptr<Node> node = *i;
Ptr<Application> app = InstallPriv (node);
apps.Add (app);
}
return apps;
}
Ptr<Application> SmtpClientHelper::InstallPriv (Ptr<Node> node) {
Ptr<SmtpClient> client = CreateObject<SmtpClient> ();
client->SetAttribute (“Remote”, AddressValue (m_address));
node->AddApplication (client);
return client;
}
} // namespace ns3
- Integrate SMTP with ns3 build system
To include your new SMTP module, update the wscript file in the src directory.
src/smtp/wscript
def build(bld):
module = bld.create_ns3_module(‘smtp’, [‘core’, ‘network’, ‘internet’, ‘applications’])
module.source = [
‘model/smtp-server.cc’,
‘model/smtp-client.cc’,
‘helper/smtp-helper.cc’,
]
headers = bld(features=’ns3header’)
headers.module = ‘smtp’
headers.source = [
‘model/smtp-server.h’,
‘model/smtp-client.h’,
‘helper/smtp-helper.h’,
]
- Build and test
Rebuild ns3 to include your new SMTP module.
./waf configure
./waf build
Create test scripts to verify the implementation of your SMTP protocol.
scratch/test-smtp.cc
#include “ns3/core-module.h”
#include “ns3/network-module.h”
#include “ns3/internet-module.h”
#include “ns3/point-to-point-module.h”
#include “ns3/smtp-helper.h”
using namespace ns3;
int main (int argc, char *argv[])
{
CommandLine cmd;
cmd.Parse (argc, argv);
NodeContainer nodes;
nodes.Create (2);
PointToPointHelper pointToPoint;
pointToPoint.SetDeviceAttribute (“DataRate”, StringValue (“5Mbps”));
pointToPoint.SetChannelAttribute (“Delay”, StringValue (“2ms”));
NetDeviceContainer devices;
devices = pointToPoint.Install (nodes);
InternetStackHelper stack;
stack.Install (nodes);
Ipv4AddressHelper address;
address.SetBase (“10.1.1.0”, “255.255.255.0”);
Ipv4InterfaceContainer interfaces = address.Assign (devices);
SmtpServerHelper smtpServer (InetSocketAddress (Ipv4Address::GetAny (), 25));
ApplicationContainer serverApps = smtpServer.Install (nodes.Get (1));
serverApps.Start (Seconds (1.0));
serverApps.Stop (Seconds (10.0));
SmtpClientHelper smtpClient (InetSocketAddress (interfaces.GetAddress (1), 25));
ApplicationContainer clientApps = smtpClient.Install (nodes.Get (0));
clientApps.Start (Seconds (2.0));
clientApps.Stop (Seconds (10.0));
Simulator::Run ();
Simulator::Destroy ();
return 0;
}
- Run and debug
Run your test script and debug any issues that arise.
./waf –run scratch/test-smtp
Overall, we had successfully implemented the Simple Mail Transfer Protocol (SMTP) in ns3 by creating modules for SMTP client and server applications, defining the protocol logic, and integrating it with ns3’s existing network simulation framework.
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