File content as of revision 0:724a1b7b59ca:

#include "mbed.h"
#include "EthernetInterface.h"
Serial pc(USBTX, USBRX);

#define SERVER_PORT   1234
#define BUFFLEN 100

int bufsize=1024;      //Size of the shared memory
char *buffer;   //This is the shared memory between the child threads

void Handle_client(void const *socket_data) {
   int socket; 
   socket = (int)socket_data;
   pc.printf("Socket connected #%d\n",socket); 
  // pthread_mutex_lock (&mutex);
   pc.printf("Shared memory message is %s\n",buffer); 
   lwip_recv(socket,buffer,bufsize,0); 


   if (lwip_send(socket,buffer,strlen(buffer),0)!=strlen(buffer)) //send the content of the shared memory back to the socket 
   {
        pc.printf("failed send\n");
   }
  
   pc.printf("Message sent successfully to socket %d\n",socket);

}

int main (void) {

    EthernetInterface eth;
    eth.init(); //Use DHCP
    eth.connect();
    pc.printf("IP Address is %s\n", eth.getIPAddress());
    int socket_server;
    struct sockaddr_in localHost;
    memset(&localHost, 0, sizeof(localHost));
    int new_socket;
    
    if( (socket_server= lwip_socket(AF_INET, SOCK_STREAM, 0))<0)
    {
        pc.printf("failed socket init\n");
        return -1;
    }
    localHost.sin_family = AF_INET;
    localHost.sin_port = htons(SERVER_PORT);
    localHost.sin_addr.s_addr = INADDR_ANY;
    
    if (lwip_bind(socket_server, (const struct sockaddr *) &localHost, sizeof(localHost)) < 0) {
        pc.printf("failed socket bind init\n");
        return -1;
    }
      if (lwip_listen(socket_server,3)<0)
  {
    perror("listen");
    exit(EXIT_FAILURE);
  }
  socklen_t newSockRemoteHostLen = sizeof(localHost);
  int tid;
  
  for(tid=0;tid<=2;tid++) 
  {
    new_socket = lwip_accept(socket_server, (struct sockaddr*) &localHost, &newSockRemoteHostLen);
    if (new_socket < 0)
    {
    pc.printf("failed socket accept\n");
        return -1;
     }

       Thread t(Handle_client, (void *) new_socket);
   }
 
}