udp_connect.h

linux 高级编程的例子源码,包括了本书上的所有代码

#ifndef UDP_CONNECT_H
#define UDP_CONNECT_H
#include "ourhead.h"

int udp_connect(const char *host,const char *service)
{
	struct hostent *phe;
	struct servent *pse;
	struct sockaddr_in sin;
	int s;
	memset(&sin,0,sizeof(sin));
	sin.sin_family=AF_INET;

	if (pse=getservbyname(service,NULL))
		sin.sin_port=pse->s_port;
	else if ((sin.sin_port=htons((u_short)atoi(service)))==0)
		return -4;

	if (phe=gethostbyname(host))
		memcpy(&sin.sin_addr,phe->h_addr,phe->h_length);
	else if ((sin.sin_addr.s_addr=inet_addr(host))==INADDR_NONE)
		return -3;

	s=socket(AF_INET,SOCK_DGRAM,0);
	if (s<0)
		return -2;

	if (connect(s,(struct sockaddr*)&sin,sizeof(sin))<0)
		return -1;
	return s;
}
#endif