[lwip-users] TCP server netconn API

[Saket Chawla]

I am trying to build a simple TCP echoserver and client for same using netconn API.

I am sure some might already have tried but i couldn't find any source on internet

My system is running ubuntu 10.10

Directory structure to refer for compile instruction

   /contrib

   /lwip

   /server.c

   /lwipopts.h

File content

    lwipopts.h  [i think there might me more required here that i don't know of]

#define LWIP_SOCKET    0

     server.c  [took the basic code from Design and Implementation of the lwIPTCP/IP Stack]

#include <stdio.h>

#include <lwip/api.h>

int main()

{

struct netconn *conn, *newconn;

err_t err;

/* create a connection structure */

conn = netconn_new(NETCONN_TCP);

/* bind the connection to port 2000 on any local IP address */

netconn_bind(conn, NULL, 7);

printf("Now listening\n");

/* tell the connection to listen for incoming connection requests */

netconn_listen(conn);

/* Grab new connection. */

err = netconn_accept(conn, &newconn);

printf("accepted new connection %p\n", newconn);

/* Process the new connection. */

if (err == ERR_OK) 

{

struct netbuf *buf;

void *data;

u16_t len;

   

while ((err = netconn_recv(newconn, &buf)) == ERR_OK) 

{

printf("Received data\n");

do{

netbuf_data(buf, &data, &len);

err = netconn_write(newconn, data, len, NETCONN_COPY);

if (err != ERR_OK)

printf("tcpecho: netconn_write: error \"%s\"\n", lwip_strerr(err));

}while (netbuf_next(buf) >= 0);

netbuf_delete(buf);

}

/* Close connection and discard connection identifier. */

netconn_close(newconn);

netconn_delete(newconn);

}

}

compile instruction

gcc -I. -I lwip/src/include/ -I contrib/ports/unix/include/ -I lwip/src/include/ipv4/ lwip/src/api/*.c lwip/src/core/*.c lwip/src/core/ipv4/*.c contrib/ports/unix/sys_arch.c lwip/src/netif/etharp.c -lpthread server.c 

Problem

All files are included and no errors / warnings occur for compile

But in netconn_bind I receive an error

Assertion "netconn_bind: invalid conn" failed at line 172 in lwip/src/api/api_lib.c

Aborted

Please let me know if i am missing something obvious

Also i did try to understand the server implementation from simhost but it is too complicated for a basic echoserver application

So any reference manual or if someone has already build such application  for a start then a link to it is deeply appreciated.

--

Thanks
Regards
Saket Chawla