C++ Creating multiple socket clients - c++

Question

I'm trying to build a simulation for multiple socket clients.
My server has the following code to listen to multiple clients
My socket are from a very simple class drive from CAsyncSocket and my environment is windows MFC.
m_server.Create(....); // with the correct values
if (m_server.Listen()==FALSE)
and later on the OnSocketAccept() function
if (m_server.Accept(tempSock))
{
CSocketThread* pThread = (CSocketThread*)AfxBeginThread(RUNTIME_CLASS(CSocketThread), THREAD_PRIORITY_NORMAL, 0, CREATE_SUSPENDED);
...
My simulation apps has the following code:
for (int i = 0; i < numOfClients; i++)
{
m_sConnected[i].Create();
int rVal = m_sConnected[i].Connect(csIPAddress.GetString(), m_port);
That doesn't work.
In WireShark I can see that my (numOfClients = 10 for example) 10 clients are connected with different client source port.
But each new socket of m_sConnected[i] is becoming NULL after the second connection to all sockets including m_sConnected[0].
Closing the sockets or destroy the simulation app create socket close at the server side for all open threads for the listen sockets.
What is the problem?
Can I use the same process/thread for all my socket clients?
10x
UrAv.

Answer 1

your problem is that you are not using the CSocketThread object the right way.
as mentiend in microsoft documention
after the accept function you need to do the following :
CSockThread* pSockThread = (CSockThread*)AfxBeginThread( RUNTIME_CLASS(CSockThread), THREAD_PRIORITY_NORMAL, 0, CREATE_SUSPENDED);
if (NULL != pSockThread) {
// Detach the newly accepted socket and save
//the SOCKET handle in our new thread object.
//After detaching it, it should no longer be
//used in the context of this thread.
pSockThread->m_hConnected = sConnected.Detach();
pSockThread->ResumeThread();
} }
when you attach your socket to the thread then it will run.
link to microsoft doc:
https://msdn.microsoft.com/en-us/library/wxzt95kb.aspx

Answer 2

your solution has worked for me. I have used multiple threads to stress test the server in c++ under linux. Pasting my code, it will be helpful to somebody...Experts can improve my code, if they find any flaws in my handling of code. I know, I am doing something wrong but no other go to test the server as no one has provided the solution for this till now. I am able to test the server for 100000 clients using this code. - Kranti.
include //for threading , link with lpthread
void *connection_handler(void *);
#define PORT 9998
#define SERVER_IP "127.0.0.1"
#define MAXSZ 100
#define MAXSOCK 70000
int main()
{
int sockfd[MAXSOCK];//to create socket
int socket_desc , new_socket[MAXSOCK], *new_sock;
struct sockaddr_in serverAddress;//client will connect on this
int n;
char msg1[MAXSZ];
char msg2[MAXSZ];
int NoOfClients = MAXSOCK;
memset(msg2,0,100);
void *ret;
for(int i=0;i<NoOfClients;i++){
//create socket
sockfd[i]=socket(AF_INET,SOCK_STREAM,0);
//initialize the socket addresses
memset(&serverAddress,0,sizeof(serverAddress));
serverAddress.sin_family=AF_INET;
serverAddress.sin_addr.s_addr=inet_addr(SERVER_IP);
serverAddress.sin_port=htons(PORT);
//client connect to server on port
new_socket[i] = connect(sockfd[i],(struct sockaddr *)&serverAddress,sizeof(serverAddress));
printf("new socket connected= %d",new_socket[i]);
pthread_t sniffer_thread[MAXSOCK];
new_sock = malloc(sizeof(int));
*new_sock = new_socket[i];
int p=-1;
if( p = pthread_create( &sniffer_thread[i] , NULL , connection_handler , (void*) new_sock) < 0)
{
perror("could not create thread");
return 1;
}
}
return 0;
}
/*
* This will handle connection for each client
* */
void *connection_handler(void *socket_desc)
{
//Get the socket descriptor
int sock = *(int*)socket_desc;
int read_size;
char *message , client_message[50];
printf("we are in connection handler");
//Send some messages to the server
message = "Greetings! I am your connection handler\n";
int wlen = write(sock , message , strlen(message));
printf("write length is %d", wlen);
//Free the socket pointer
//close(sock);
free(sock);
return 0;
}