tcp.c

/* tcp.c
 * By Ron
 * Created August, 2008
 *
 * (See LICENSE.txt)
 */

#include <stdio.h>
#include <string.h>

#ifdef WIN32
#include <winsock2.h>
#else
#include <netdb.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <sys/types.h>
#endif

#include "tcp.h"

void winsock_initialize()
{
#ifdef WIN32
	WORD wVersionRequested = MAKEWORD(2, 2);
	WSADATA wsaData;

	int error = WSAStartup(wVersionRequested, &wsaData);

	switch(error)
	{
	case WSASYSNOTREADY:
		fprintf(stderr, "The underlying network subsystem is not ready for network communication.\n");
		exit(1);
		break;

	case WSAVERNOTSUPPORTED:
		fprintf(stderr, "The version of Windows Sockets support requested is not provided by this particular Windows Sockets implementation.\n");
		exit(1);
		break;

	case WSAEINPROGRESS:
		fprintf(stderr, "A blocking Windows Sockets 1.1 operation is in progress.\n");
		exit(1);
		break;

	case WSAEPROCLIM:
		fprintf(stderr, "A limit on the number of tasks supported by the Windows Sockets implementation has been reached.\n");
		exit(1);
		break;

	case WSAEFAULT:
		fprintf(stderr, "The lpWSAData parameter is not a valid pointer.\n");
		exit(1);
		break;
	}
#endif
}

int tcp_connect(char *host, uint16_t port)
{
	struct sockaddr_in serv_addr;
	struct hostent *server;

	/* Create the socket */
	int s = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);

	if (s == -1)
	{
		nbdie("tcp: couldn't create socket");
	}
	else
	{
		/* Look up the host */
		server = gethostbyname(host);
		if(!server)
		{
			s = -1;
			fprintf(stderr, "Couldn't find host %s\n", host);
		}
		else
		{
			/* Set up the server address */
			memset(&serv_addr, '\0', sizeof(serv_addr));
			serv_addr.sin_family = AF_INET;
			serv_addr.sin_port   = htons(port);
			memcpy(&serv_addr.sin_addr, server->h_addr_list[0], server->h_length);

			/* Connect */
			if (connect(s, (struct sockaddr*)&serv_addr, sizeof(serv_addr)) < 0)
			{
				s = -1;
				nberror("tcp: couldn't connect to host");
			}
		}
	}

	return s;
}

int tcp_listen(char *address, uint16_t port)
{
	int s;
	struct sockaddr_in serv_addr;

	/* Get the server address */
	memset((char *) &serv_addr, '\0', sizeof(serv_addr));
	serv_addr.sin_family = AF_INET;
	serv_addr.sin_addr.s_addr = inet_addr(address);
	serv_addr.sin_port = htons(port);

	if(serv_addr.sin_addr.s_addr == INADDR_NONE)
		nbdie("tcp: couldn't parse local address");

	/* Create a socket */
	s = socket(AF_INET, SOCK_STREAM, 0);
	if(s < 0)
	{
		nbdie("tcp: couldn't create socket");
	}
	else
	{
		/* Bind the socket */
		if (bind(s, (struct sockaddr *) &serv_addr, sizeof(serv_addr)) < 0)
			nbdie("tcp: couldn't bind to socket");

		/* Switch the socket to listen mode. TODO: why 20? */
		if(listen(s, 20) < 0)
			nbdie("tcp: couldn't listen on socket");
	}

	return s;
}

int tcp_accept(int listen, char **address, uint16_t *port)
{
	struct sockaddr_in addr;
	socklen_t sockaddr_len = sizeof(struct sockaddr_in);
	int s;

	s = accept(listen, (struct sockaddr *) &addr, &sockaddr_len);

	if(s < 0)
		nbdie("tcp: couldn't accept connection");

	*address = inet_ntoa(addr.sin_addr);
	*port    = ntohs(addr.sin_port);

	return s;
}

size_t tcp_send(int s, void *data, size_t length)
{
	return send(s, data, length, 0);
}

size_t tcp_recv(int s, void *buffer, size_t buffer_length)
{
	return recv(s, buffer, buffer_length, 0);
}

int tcp_close(int s)
{
#ifdef WIN32
	return closesocket(s);
#else
	return close(s);
#endif
}

#if 0
int main(int argc, char *argv[])
{
	char buffer[1024];
	int s;
	int listener;
	struct sockaddr_in addr;
	int port;
	size_t len;

	memset(buffer, 0, 1024);

	winsock_initialize();

	s = tcp_connect("www.google.ca", 80);
	if(s < 0)
		DIE("Fail");
	tcp_send(s, "GET / HTTP/1.0\r\nHost: www.google.com\r\n\r\n", 41);
	tcp_recv(s, buffer, 1024);
	tcp_close(s);

	printf("%s\n", buffer);

	printf("Listening on TCP/6666\n");
	listener = tcp_listen("0.0.0.0", 6666);
	s = tcp_accept(listener, &addr, &port);

	if(s < 0)
		DIE("Fail");

	printf("Connection accepted from %s:%d\n", inet_ntoa(addr.sin_addr), ntohs(addr.sin_port));

	memset(buffer, 0, 1024);
	strcpy(buffer, "HELLO!");
	len = 7;
	while(len > 0 && tcp_send(s, buffer, len) >= 0)
	{
		memset(buffer, 0, 1024);
		len = tcp_recv(s, buffer, 1024);
		printf("Received: %s [%d]\n", buffer, len);
	}

	printf("%s\n", buffer);
	return 0;
}
#endif