listen(sock, backlog):
In my opinion, the parameter backlog limits the number of connection. Here is my test code:
// server
// initialize the sockaddr of server
server.sin_family = AF_INET;
server.sin_addr.s_addr = INADDR_ANY;
server.sin_port = htons( 8888 );
bind(...);
listen(sock, 1);
while( (client_sock = accept(...)) )
{
// create a thread for one client
if( pthread_create( &sniffer_thread , NULL , connection_handler , (void*) new_sock) < 0)
{
perror("could not create thread");
return 1;
}
}
// client
server.sin_addr.s_addr = inet_addr("127.0.0.1");
server.sin_family = AF_INET;
server.sin_port = htons( 8888 );
connect(...);
while(1)
{
scanf("%s" , message);
//Send some data
if( send(sock , message , strlen(message) , 0) < 0)
{
puts("Send failed");
return 1;
}
//Receive a reply from the server
if( recv(sock , server_reply , 2000 , 0) < 0)
{
puts("recv failed");
break;
}
puts("Server reply :");
puts(server_reply);
}
On my own PC, I execute the server, which is waiting for clients.
Then I execute two clients, both of them can send and receive messages.
Here is what I don't understand:
Why does my server can accept two different clients (two different sockets)?
I set the parameter of backlog as 1 for the listen of the server, why does it can still hold more than one client?