Thread: Help with multithreaded sockets program

Hello.

I'm trying to learn how to use threads and sockets in C. To do this, I've written a program that does the following:
1) Spawns a thread, which then starts listening on a server socket
2) Opens a client socket, and sends a message through
3) On the server side, reads the message and prints it out

Here's my code:

Code:

#include <sys/socket.h>
#include <netinet/in.h>
#include <stdio.h>
#include <pthread.h>
#include <unistd.h>
#include <errno.h>

#define PORT_NO 1234
	
typedef int Socket;
typedef pthread_t Thread;

void* do_server(void*);
void* do_client(void*);
			
int main(void) {
	
	Thread other_thread;
	int ret = pthread_create(&other_thread, NULL, do_server, NULL);
	if(ret < 0)
		printf("Trouble creating thread in main...\n");
	
//	printf("%s", "Going to sleep...\n");
	sched_yield();
	sleep(2);
//	printf("%s", "Waking up...\n");
	
	do_client(NULL);
	
	pthread_exit(NULL);
	
    return 0;
				
}

void* do_server(void* param) {
	
	printf("%s", "In server code...\n");
	
	Socket my_socket = socket( PF_INET , SOCK_STREAM , 0 );
	if(my_socket < 0)
		printf("%s", "Socket creation failed in server...\n");
	struct sockaddr_in address;
	address.sin_family = AF_INET;
	address.sin_addr.s_addr = htonl(INADDR_ANY);
	address.sin_port = htons(PORT_NO);
						
	int res = bind( my_socket, (struct sockaddr*) &address, sizeof(struct sockaddr_in));
	
	if(res < 0)
		printf("Trouble binding socket...\n");
	
	res = listen( my_socket, 5 );
	if(res < 0)
		printf("Couldn't listen to socket...\n");
	
	struct sockaddr_in remote_address;
	socklen_t remote_address_len;
	Socket new_socket;
	
	printf("Accepting...\n");
	new_socket = 
		accept( my_socket,  (struct sockaddr*) &remote_address,
							&remote_address_len);
	
	
	if(new_socket < 0) {
		printf("Couldn't accept connection...");
		switch(errno) {
		case EBADF:
			printf("Bad file descriptor\n");
			break;
		case ENOTSOCK:
			printf("Descriptor is not a socket\n");
			break;
		case EOPNOTSUPP:
			printf("Operation not supported\n");	
			break;
		case EWOULDBLOCK:
			printf("Would block\n");
			break;
		default:
			printf("Unknown error code: %d\n", errno);
			break;
		}
	}
	
	void* data = malloc(0x0400); /* 1k */
	res = recv(new_socket, data, 1024, 0);
	printf("%d bytes received", res);
	
	printf("%s\n", (char*) data);
	free(data);
	
	shutdown(my_socket, 2);
	shutdown(new_socket, 2);
	
	printf("Exiting server code...\n");
	pthread_exit(NULL);
}

void* do_client(void* param) {
	
	printf("%s", "Running client code...\n");
	
	Socket my_socket = socket( PF_INET , SOCK_STREAM , 0 );
	if(my_socket < 0)
		printf("%s", "Socket creation failed in client...\n");
	struct sockaddr_in address;
	address.sin_family = AF_INET;
	address.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
	address.sin_port = htons(PORT_NO);
	
	int res = connect( my_socket, (struct sockaddr*) &address, sizeof(struct sockaddr));
	if(res < 0)
		printf("Trouble connecting...\n");
	
	const char MSSG[] = "Hello, there!";
	
	res = send( my_socket, MSSG, sizeof(MSSG), 0);
	printf("%d bytes sent\n", res);
	
	printf("%s", "Going to sleep in client code...\n");
	sched_yield();
	sleep(2);
	
	shutdown(my_socket, 2);
	printf("Client thread exiting...\n");
	pthread_exit(NULL);
	
}

This has *occasionally* worked, leading me to believe that I'm on the right track, but this is the output I'm getting now:

Code:

In server code...
Accepting...
Running client code...
14 bytes sent
Going to sleep in client code...
Couldn't accept connection...Unknown error code: 22
-1 bytes received
Exiting server code...
Client thread exiting...

Does anyone know what I'm doing wrong? Thanks.
Cooper

Thanks, that fixed it. I was using the GNU C Standard Library manual, which (oddly) doesn't mention this.