passsock.cpp

这是用c++编写的代码,用tcp,udp形式进行网络编程,代码很好.

/* passsock.cpp - passivesock */

#include <stdlib.h>
#include <string.h>
#include <winsock.h>

void	errexit(const char *, ...);

u_short	portbase = 0;		/* port base, for test servers		*/

/*------------------------------------------------------------------------
 * passivesock - allocate & bind a server socket using TCP or UDP
 *------------------------------------------------------------------------
 */
SOCKET
passivesock(const char *service, const char *transport, int qlen)
{
	struct servent	*pse;	/* pointer to service information entry	*/
	struct protoent *ppe;	/* pointer to protocol information entry*/
	struct sockaddr_in sin;	/* an Internet endpoint address		*/
	SOCKET		s;	/* socket descriptor			*/
	int		type;	/* socket type (SOCK_STREAM, SOCK_DGRAM)*/

	memset(&sin, 0, sizeof(sin));
	sin.sin_family = AF_INET;
	sin.sin_addr.s_addr = INADDR_ANY;

    /* Map service name to port number */
	if ( pse = getservbyname(service, transport) )
		sin.sin_port = htons(ntohs((u_short)pse->s_port)
			+ portbase);
	else if ( (sin.sin_port = htons((u_short)atoi(service))) == 0 )
		errexit("can't get \"%s\" service entry\n", service);

    /* Map protocol name to protocol number */
	if ( (ppe = getprotobyname(transport)) == 0)
		errexit("can't get \"%s\" protocol entry\n", transport);

    /* Use protocol to choose a socket type */
	if (strcmp(transport, "udp") == 0)
		type = SOCK_DGRAM;
	else
		type = SOCK_STREAM;

    /* Allocate a socket */
	s = socket(PF_INET, type, ppe->p_proto);
	if (s == INVALID_SOCKET)
		errexit("can't create socket: %d\n", GetLastError());

    /* Bind the socket */
	if (bind(s, (struct sockaddr *)&sin, sizeof(sin)) == SOCKET_ERROR)
		errexit("can't bind to %s port: %d\n", service,
			GetLastError());
	if (type == SOCK_STREAM && listen(s, qlen) == SOCKET_ERROR)
		errexit("can't listen on %s port: %d\n", service,
			GetLastError());
	return s;
}