Segmentation Violation

[Muhammad Talha]

Hi, 
Im not that familiar with C programming or socket programming and have been stuck on the issue for the last 2 days.
Im on ns3.42 with python cppyy binding. (which is probably causing the issue)

Ive simplified the script to only be the error part. Its simply 2 sockets on a p2p connection sending a packet from 1 to the other. The receiver just prints that it received the packet.

Im getting a segmentation violation error and it fails on line 90 where is sends the packet. Could anyone guide me as to what the issue could be

[Muhammad Talha]

I've tried to retry from the groud up multiple times but always end up at the same error when using "socket.Send". Do i have to make another cppyy.cppdef function to make sure it sends properly?

ns.cppyy.cppdef("""
namespace ns3
{
    void RecvCallback(Ptr<Socket> socket) {
        if (socket->Recv()) {
            std::cout << "Received one packet!" << std::endl;
        }
    }            
   
    Callback<void, Ptr<Socket>> MakeRecvCallback()
    {
        return MakeCallback(&RecvCallback);
    }
               
}
""")

ns.LogComponentEnable("UdpSocketImpl", ns.LOG_LEVEL_INFO)
ns.LogComponentEnable("Ipv4L3Protocol", ns.LOG_LEVEL_INFO)
ns.LogComponentEnable("ArpL3Protocol", ns.LOG_LEVEL_INFO)

packetsize = 64 #bytes
pktcount = 2
pktinterval = 0.25 #seconds

nodes = ns.NodeContainer()
nodes.Create(2)

p2p = ns.PointToPointHelper()
p2p.SetDeviceAttribute("DataRate", ns.StringValue("5Mbps"))
p2p.SetChannelAttribute("Delay", ns.StringValue("2ms"))
devices = p2p.Install(nodes)

internet = ns.InternetStackHelper()
internet.Install(nodes)

address = ns.Ipv4AddressHelper()
address.SetBase(ns.Ipv4Address("10.1.1.0"), ns.Ipv4Mask("255.255.255.0"))
interfaces = address.Assign(devices)

def RecPkt(socket):
    if socket.Recv():
        print ("Received one packet!")

def SndPkt(socket):
    if pktcount > 0:
        socket.Send(ns.Packet(1024))
        #ns.Simulator.Schedule(pktinterval, SndPkt, socket, packetsize, pktcount-1, pktinterval)
        print ("Sending one packet!")
    else:
        socket.Close()

appSource = nodes.Get(0)
appSink = nodes.Get(1)

remoteAddr = interfaces.GetAddress(1)

sink = ns.Socket.CreateSocket(appSink, ns.TypeId.LookupByName("ns3::UdpSocketFactory"))
sink.Bind(ns.InetSocketAddress(ns.Ipv4Address.GetAny(), 80).ConvertTo())

# Use the C++ MakeRecvCallback function
MakeRecvCallback = ns.MakeRecvCallback
recv_callback = MakeRecvCallback()
sink.SetRecvCallback(recv_callback)

source = ns.Socket.CreateSocket(appSource, ns.TypeId.LookupByName("ns3::UdpSocketFactory"))
source.Connect(ns.InetSocketAddress(remoteAddr, 80).ConvertTo())

ns.Simulator.Schedule(ns.Seconds(30.0), SndPkt(source))

#source.Send(ns.Packet(1))

print ("Run Simulation.")
ns.Simulator.Stop(ns.Seconds(100))
ns.Simulator.Run()
ns.Simulator.Destroy()

[Muhammad Talha]

Sorry for the poor english grammar.

[Muhammad Talha]

Update:

I've attempted to implement the socket binding, connection, and callback part in C directly. However, I'm not very comfortable with C programming. It seems that the StartApplication function is not working because there's no output from NS_LOG_UNCOND("Sender App Start"). Could someone guide me on the issue with either the new code or the previous code? I'm concerned that I might be making a fundamental mistake or missing a concept, as I'm new to socket programming. Any help would be greatly appreciated.

Output:
[runStaticInitializersOnce]: Failed to materialize symbols: { (main, { __cxx_global_var_initcling_module_139_, __orc_init_func.cling-module-139, _GLOBAL__sub_I_cling_module_139, _ZN3ns3L16g_timeInitHelperE, $.cling-module-139.__inits.0 }) }
[runStaticInitializersOnce]: Failed to materialize symbols: { (main, { __orc_init_func.cling-module-139 }) }
Creating nodes
Creating point-to-point link
Device 0 type: ns3::PointToPointNetDevice
Device 1 type: ns3::PointToPointNetDevice
Installing internet stack
Assigning IP addresses
Creating receiver sockets
0x56df135d8300
Creating sender socket
ns3::Socket
Running simulation
looking for ns3::SocketSetDontFragmentTag
looking for ns3::SocketIpTtlTag
found initial merge before tid
tid not found after first merge
looking for ns3::SocketIpTosTag
found initial merge before tid
tid not found after first merge
Sojourn time +0ms
looking for ns3::SocketPriorityTag
found initial merge before tid
tid not found after first merge
looking for ns3::SocketPriorityTag
found initial merge before tid
tid not found after first merge
 The socket was not bound to any group.
 The socket was not bound to any group.
Simulation finished