Two or more implicit connections at the same time

[Suslsuk]

Discussed in #440

^{Originally posted by Suslsuk April 4, 2023}
sample_application.zip
Hello,

I've used the sample application as a template to create two exclusive connections with In/Out/Config assemblies. I am using a rockwell PLC and the Hilscher Ethernet/IP Tool to connect to these two connections. As long as I use just one connection, everything is working fine. But when I try to establish an additional connection ( one is active ) then the already established connection gets disconnected in the CheckAndHandleConsumingUdpSocket function (received_size == 0 or received_size == -1) and the new connection becomes active and exchanges data.

Would be great if some comes up with an idea, Thanks

OS: Windows 10 x64

Log-Messages:

IO Exclusive Owner connection requested
No PIT segment available
networkhandler: UDP socket 536
New highest socket: 536
connection manager: connect succeeded
assembleFWDOpenResponse: sending success response
notifyMR: notify function of class 'connection manager' returned a reply
TCP reply: send 110 bytes on 260
Entering HandleDataOnTcpSocket for socket: 260
Data received on TCP: 24
Handles data for TCP socket: 260
unregister session
encap.c: Unregister Session Command
Closing TCP socket 260
networkhandler: closing socket 260
networkhandler: closing socket done 260
UDP packet to be sent to: 239.192.70.224:2222
UDP packet to be sent to: 239.192.70.224:2222
Processing UDP consuming message
networkhandler: error on recv: 10035 - Ein nicht blockierender Socketvorgang konnte nicht sofort ausgeführt werden.
Exclusive Owner or Input Only connection closed - Instance type: 2
Close all instance type 4 only connections
Closing UDP socket 504
networkhandler: closing socket 504
networkhandler: closing socket done 504
Closing UDP socket 504
networkhandler: closing socket 504
networkhandler: closing socket done 504
cipioconnection: CloseCommunicationChannelsAndRemoveFromActiveConnectionsList
UDP packet to be sent to: 239.192.70.224:2222
Processing UDP consuming message
Starting data length: 38
data length after sequence count: 36
Run/Idle handler: 0x1
Setting extended status: 60

Code:

`void CheckAndHandleConsumingUdpSocket(void) {
DoublyLinkedListNode *iterator = connection_list.first;

CipConnectionObject *current_connection_object = NULL;

/* see a message of the registered UDP socket has been received */
while(NULL != iterator) {
current_connection_object = (CipConnectionObject ) iterator->data;
iterator = iterator->next; / do this at the beginning as the close function may can make the entry invalid */

if( (kEipInvalidSocket !=
     current_connection_object->socket[kUdpCommuncationDirectionConsuming])
    && (true ==
        CheckSocketSet(current_connection_object->socket[
                         kUdpCommuncationDirectionConsuming
                       ]) ) ) {
  OPENER_TRACE_INFO("Processing UDP consuming message\n");
  struct sockaddr_in from_address = { 0 };
  socklen_t from_address_length = sizeof(from_address);
  CipOctet incoming_message[PC_OPENER_ETHERNET_BUFFER_SIZE] = { 0 };

  int received_size = recvfrom(g_network_status.udp_io_messaging, NWBUF_CAST incoming_message, sizeof(incoming_message),
    0, (struct sockaddr*) &from_address, &from_address_length);
  if(**0 == received_size**) {
    int error_code = GetSocketErrorNumber();
    char *error_message = GetErrorMessage(error_code);
    OPENER_TRACE_ERR(
      "networkhandler: socket: %d - connection closed by client: %d - %s\n",
      current_connection_object->socket[
        kUdpCommuncationDirectionConsuming],
      error_code,
      error_message);
    FreeErrorMessage(error_message);
    current_connection_object->connection_close_function(current_connection_object);
    continue;
  }

  if(####0 > received_size#####) {
    int error_code = GetSocketErrorNumber();
    char *error_message = GetErrorMessage(error_code);
    if(OPENER_SOCKET_WOULD_BLOCK == error_code) {
      return; // No fatal error, resume execution
    } OPENER_TRACE_ERR("networkhandler: error on recv: %d - %s\n",
                       error_code,
                       error_message);
    FreeErrorMessage(error_message);
    current_connection_object->connection_close_function(current_connection_object);
    continue;
  }

  HandleReceivedConnectedData(incoming_message, received_size,
                              &from_address);

}

}
}`

[MartinMelikMerkumians]

Your error is rather interesting, as the error seems after sending to a multicast group. A wireshark trace from the problematic message could help to indentify the issue.

Another topic is a different part of your error log

Exclusive Owner or Input Only connection closed - Instance type: 2
Close all instance type 4 only connections

This should read instance type 1 and instance type 3 connection if I am not mistaken. I need to check this too in the code, if this is wrong in the repository

[Suslsuk]

I created a trace at the time of activation of the second connection. Thank you

opener_wireshark_filter.zip