Ethernet Gateway DR - Sending but not Receive using Sockets

[tjlarso]

Hello. I have been working on a project that uses our own C++ implementation using the win32 sockets library for transmitting and receiving messages from a pc to a PCAN-Ethernet Gateway DR. Attached is how I have the device configured to connect to the Gateway.

pcan help.PNG (24.65 KiB) Viewed 2874 times

I set it up to where my laptop is the server, with an IP of "192.168.1.20" on port "5001". The client is the gateway and I am having trouble with the "server.accept()" function where it is waiting for a response from the gateway, but it never comes. Here is the code for that.

Code: Select all

bool CANGateway::connect()
{
    #pragma region server_connect

    SocketServer server;
    server.bind("192.168.1.20", "5001");
    SOCKET clientSock;

    while(true)
    {
        clientSock = server.accept();
        if(clientSock != INVALID_SOCKET)
            break;
    }

    cout << "connected and bound to server" << endl;
    SocketServerConn client(clientSock);

    while(true)
    {
        char val;
        int ret = client.recv(&val, 1, VirtualSocket::WAIT);
        if(ret < 0)
        {
            cout<<"Error receiving data: "<<ret<<endl;
            exit(1);
        }
        else if(ret > 0)
        {
            cout<<"got "<<val<<endl;
            client.send(&val, 1);
            if(val == '\n')
            {
                cout<<"Got end of string!"<<endl;
                break;
            }
        }
        else {/*empty*/}
    }
    #pragma endregion server_connect 

    int ret = _txSock.connect("192.168.1.10", "5000"); //PCAN gateway IP/port
    cout << "_txSock connected status: " << ret << endl;
    
    return ret;
}

My main question is what is the behavior of the gateway supposed to do and how can I get the gateway to send a confirmation back to my server confirming that it is connected so that my accept function can go through. Here is the accept function in my sockets library.

Code: Select all

SOCKET SocketServer::accept()
{

    if(_listenSock == INVALID_SOCKET)
    {
        throw runtime_error("Server not bound!");
    }
    // Accept a client socket
    SOCKET clientSock;

    clientSock = ::accept(_listenSock, NULL, NULL);      // stuck here 

    if(clientSock == INVALID_SOCKET)
    {
        cout << "nothing connected" << endl;
    }

    return clientSock;
}

If you can, please help me with this behavior and if applicable point me in the right direction of which documentation covers this, as I have not been able to find anything. Best and thank you!

[M.Heidemann]

Hello,

Seems like you are starting from scratch here,
maybe you want to have a look at our example code (C),
which includes both an RX and TX example.

PCAN_Ethernet_Gateway_DR_RXTX_Sample.zip

(10.45 KiB) Downloaded 1898 times

Best Regards

Marvin

[tjlarso]

Thank you Marvin! I have had the chance to review that code previously, and it has not really guided me in the direction I would like to be in yet.

Alternatively, after looking through more documentation I decided to go into my poi_config for the gateway and for my [rt_1] which is CAN2LAN, I made "invert_socket_mode" true instead of the default of false. This is in hopes that I can get a message back from the gateway in a client -> client manner with no server implimentation needed, which might end up being more simple.

Code: Select all

bool CANGateway::connect()
{

    #pragma region server_connect // it is commented out


    /*
    SocketServer server;
    server.bind("192.168.1.20", "5001");
    SOCKET clientSock;

    while(true)
    {
        clientSock = server.accept();
        if(clientSock != INVALID_SOCKET)
            break;
    }

    cout << "connected and bound to server" << endl;
    SocketServerConn client(clientSock);

    while(true)
    {
        char val;
        int ret = client.recv(&val, 1, VirtualSocket::WAIT);
        if(ret < 0)
        {
            cout<<"Error receiving data: "<<ret<<endl;
            exit(1);
        }
        else if(ret > 0)
        {
            cout<<"got "<<val<<endl;
            client.send(&val, 1);
            if(val == '\n')
            {
                cout<<"Got end of string!"<<endl;
                break;
            }
        }
        else {//empty}
    }
    */
    #pragma endregion server_connect 
    
    int ret = _txSock.connect("192.168.1.10", "5000"); //sends
    cout << "_txSock connected status: " << ret << endl;
    int ret2 = _rxSock.connect("192.168.1.10", "5001"); //receives
    cout<< "_rxSock connected status: " << ret2 << endl;

    char msgData[] = {"connect\n"};
    _rxSock.send(msgData);

    char c;
    bool done = false;
    while(!done)
    {
        int ret = _rxSock.recv(&c, 1, VirtualSocket::WAIT);
        if(ret > 0)
        {
            cout<<"got "<<c<<endl;
        }
        else if(ret == 0)
        {
            cout<<"Done because the server disconnected"<<endl;
            done = true;
        }
        else
        {
            cerr<<"Error in recv: "<<ret<<endl;
            exit(1);
        }
    }
    cout<<"DONE!!"<<endl;

    return ret;
}

With this, I still am getting stuck in my recv -> accept function, however, it is now giving me this information attached below. I have tried researching it but have not had any success in finding a fix for the "IP Errors". This means it knows it is supposed to be getting a message, but is not... do you know any way to fix this or any documentation that covers this? Thank you again and best!

pcan help 2.PNG (147.05 KiB) Viewed 2856 times

[tjlarso]

here is also my poi_config for my gateway to potentially provide a little more context for you.

Code: Select all

#########################################
# PoI configuration file
# 
# BSP version 2.9.1
######################################### 
[general]
ini_version                    = 2.0.1
description                    = CAN to LAN Gateway in DIN Rail Plastic Casing
kl15_pwdn                      = 0
device_id                      = 2147483647


[host]
devicename                     = PCAN-Ethernet Gateway DR


[lan_0]
if_name                        = eth0
use_dhcp                       = 0
ip_v4                          = 192.168.1.10
subnet_mask                    = 255.255.255.0
ip_v6                          = ::
ip_v4_gw                       = 0.0.0.0
ip_v6_gw                       = ::


[can_0]
if_name                        = First CAN interface
active                         = 1
listen_only                    = 0
auto_resume                    = 1
loop_back                      = 0
one_shot                       = 0
triple_sampling                = 0
br_def                         = 0
core_clock                     = 24000000
bit_rate                       = 500000
sample_point                   = 800
enable_error_counter           = 0
measure_bus_load               = 0


[can_1]
if_name                        = Second CAN interface
active                         = 1
listen_only                    = 0
auto_resume                    = 1
loop_back                      = 0
one_shot                       = 0
triple_sampling                = 0
br_def                         = 0
core_clock                     = 24000000
bit_rate                       = 500000
sample_point                   = 800
enable_error_counter           = 0
measure_bus_load               = 0


[rt_0]
rt_info                        = 
active                         = TRUE
type                           = LAN2CAN
interface_1                    = can0
protocol_2                     = TCP
destination_2                  = 0.0.0.0:5000
fpp                            = 15
tcp_delay                      = TRUE
disp_idx                       = 0
snd_delay_us                   = 1000
snd_max                        = 30
connect_delay_ms               = 500
invert_socket_mode             = FALSE
use_crc_frm                    = FALSE
crc_start_value                = 0x00000000
crc_polynom                    = 0x04C11DB7
no_ctrl                        = TRUE
no_keep_alive                  = FALSE
unify_filters                  = FALSE
join_filters                   = FALSE


[fwd_gen]
count_max                      = 16
count                          = 2


[gui]
show_device_info               = 1
show_can_info                  = 0
show_lan_info                  = 0
show_wlan_info                 = 0
show_bt_info                   = 0
show_routing_info              = 0
show_contact_info              = 1
show_support_info              = 1
show_filter_info               = 1


[json]
enable_json                    = 1
respect_gui_pub                = 1
enable_json_config             = 0
enable_json_shell              = 0


[rt_1]
rt_info                        = 
active                         = TRUE
type                           = CAN2LAN
interface_1                    = can0
protocol_2                     = TCP
destination_2                  = 0.0.0.0:5001
fpp                            = 15
tcp_delay                      = TRUE
disp_idx                       = 0
snd_delay_us                   = 300
snd_max                        = 30
connect_delay_ms               = 500
invert_socket_mode             = TRUE
use_crc_frm                    = FALSE
crc_start_value                = 0x00000000
crc_polynom                    = 0x04C11DB7
no_ctrl                        = TRUE
no_keep_alive                  = FALSE
unify_filters                  = FALSE
join_filters                   = FALSE

[M.Heidemann]

Please have another look at the examples, your code seems to skip crucial steps here:

Code: Select all

	/* Set socket option SO_REUSEADDR
	 * Indicates that the rules used in validating addresses supplied in a bind(2)
	 *  call should allow reuse of local addresses. For PF_INET sockets this means
	 *  that a socket may bind, except when there is an active listening socket bound
	 *  to the address. When the listening socket is bound to INADDR_ANY with a specific
	 *  port then it is not possible to bind to this port for any local address.
	 */
	retVal = setsockopt(sockID, SOL_SOCKET, SO_REUSEADDR, &optval, sizeof(optval));
	if(retVal < 0){
		perror("error using setsockopt (SOL_SOCKET, SO_REUSEADDR)");
		exit(-2);			   				/* Rückkehr bei Fehler */
	}

	// Enable keepalive packets
	retVal = setsockopt(sockID, SOL_SOCKET, SO_KEEPALIVE, &optval, sizeof(optval));
	if(retVal < 0){
		perror("error using setsockopt (SOL_SOCKET, SO_KEEPALIVE)");
		exit(-2);			   				/* Rückkehr bei Fehler */
	}

	retVal = setsockopt(sockID, SOL_IP, IP_RECVERR, &optval, sizeof(int));
	if(retVal < 0){
		perror("error using setsockopt (SOL_IP, IP_RECVERR)");
		exit(-2);			   				/* Rückkehr bei Fehler */
	}

	//Config Socket
	memset((char *) &sockname, 0, sizeof(struct sockaddr_in));	/* unbenutzte Bytes loeschen! */
	sockname.sin_family = AF_INET;	   							/* IP-Adresse aufsetzen */
	sockname.sin_port = htons(port);							/* Portnummer des Services */
	sockname.sin_addr.s_addr = htonl(INADDR_ANY);				/* wildcard */


    if (bind(sockID, (const struct sockaddr*) &sockname, sizeof(sockname)) < 0){	    /* an Adresse binden */
		perror("unable to bind socket");
		exit(-2);			   				/* Rückkehr bei Fehler */
    }

    if (type == SOCK_STREAM){
    	struct sockaddr peer_addr;
    	socklen_t addr_len;

		if (listen(sockID, queue_len) < 0){
			perror("unable to listen to clients");
			exit(-2);			   				/* Rückkehr bei Fehler */
		}

		sockID = accept(sockID, &peer_addr, &addr_len);
    }

	return sockID;
}//priv_openSocketIn()

I don't see much in terms of socket configuration, for example.

Can you tell me, what exactly you are trying to achieve that is not covered by the example?

Best Regards

Marvin

[tjlarso]

No worries Marvin! I have revisited the code since my last comment and it is all working as expected now! I appreciate your help today on this topic and wish you the kindest of regards.

Best and thank you,
TJ

[M.Heidemann]

That's great to hear!

If you have any further questions, feel free to create a new topic!

BR

Marvin

-closed-