client makes multiple connections to server - c

Question

I have updated my code to this based on research:
while (number_of_connections--) {
client_sock = socket(AF_INET , SOCK_STREAM , 0);
if (connect(client_sock , (struct sockaddr *)&server , sizeof(server)) < 0)
{
perror("connect failed. Error");
}
printf("socket %d created\n", client_sock);
pthread_t sniffer_thread;
new_sock = malloc(1);
*new_sock = client_sock;
if( pthread_create( &sniffer_thread , NULL , connection_handler , (void*) new_sock) < 0)
{
perror("could not create thread");
return 1;
}
}
Then I'm handling it with this function:
void *connection_handler(void *socket_desc)
{
//Get the socket descriptor
int sock = *(int*)socket_desc;
int read_size, cursor;
char *message , client_message[2000];
//Send some messages to the client
char handshakeBuf[sizeof(handshake)];
memcpy(handshakeBuf, &handshake, sizeof(handshake));
handshake.a++;
handshake.c = 0xac;
handshake.d = 0x0d;
//Send some data
if( send(sock , handshakeBuf , sizeof(handshakeBuf) , 0) < 0)
{
puts("Send failed");
}
//keep communicating with server
while(1)
{
//Receive a reply from the server
if( recv(sock , client_message , 2000 , 0) < 0)
{
puts("recv failed");
break;
}
puts(client_message);
}
close(sock);
return 0;
}
Now my problem is why does it suddenly stop when it reaches the 4th connection?
Original Question
I am trying to write my first C client. I needed to create 4 connections to the server from one client to simulate 4 clients connected where each connection of course has its own handler.
Here is what I have so far:
void connect_to_server(struct sockaddr_in server);
int main(int argc , char *argv[])
{
int number_of_connections, x;
struct sockaddr_in server;
server.sin_addr.s_addr = inet_addr("ipaddress");
server.sin_family = AF_INET;
server.sin_port = htons( port );
number_of_connections = 4;
for ( x = 0; x < number_of_connections; x++ ) {
connect_to_server(server);
}
return 0;
}
void connect_to_server(struct sockaddr_in server) {
int sock;
char message[1000] , server_reply[2000];
sock = socket(AF_INET , SOCK_STREAM , 0);
if (sock == -1)
{
printf("Could not create socket");
}
puts("Socket created");
if (connect(sock , (struct sockaddr *)&server , sizeof(server)) < 0)
{
perror("connect failed. Error");
}
while(1)
{
scanf("%s" , message);
if( send(sock , message , strlen(message) , 0) < 0)
{
puts("Send failed");
}
if( recv(sock , server_reply , 2000 , 0) < 0)
{
puts("recv failed");
break;
}
puts(server_reply);
}
close(sock);
}
Well I'm obviously also new to C. So what is wrong? Should I declare more sockets like: int sockA, sockB, sockC, sockD or I guess its the while loop inside the connect_to_server?

Answer 1

It seems the new version of the implementation uses multithreading: pthread_create(...) function call. But is there an implementation of waiting after the threads are created?
For example, the waiting can be implemented:
by using pthread_join(...) function call;
by waiting for specific key press event using getchar() function call.
Notes
Please be careful with these statements:
if (send(sock, handshakeBuf, sizeof(handshakeBuf), 0) < 0)
if (recv(sock, client_message, 2000 , 0) < 0)
The send() and recv() functions do not guarantee that the entire buffer will be sent/received after one function call. The functions return the actual number of sent/received bytes.
Please introduce analysis of the returned value for send() and recv() function calls: continue sending if not all bytes are sent, continue receiving if "not enough" bytes are received. Also, there is an article related to the some basics of the network programming: TCP/IP client-server application: exchange with string messages.