daytimetcpcli3.c

来自「Unix网络编程 基于Socket的网络编程」· C语言 代码 · 共 59 行

#include	"unp.h"

int
main(int argc, char **argv)
{
	int					sockfd, n;
	char				recvline[MAXLINE + 1];
	struct sockaddr_in	servaddr;
	struct sockaddr_in6	servaddr6;
	struct sockaddr		*sa;
	socklen_t			salen;
	struct in_addr		**pptr;
	struct hostent		*hp;
	struct servent		*sp;

	if (argc != 3)
		err_quit("usage: daytimetcpcli3 <hostname> <service>");

	if ( (hp = gethostbyname(argv[1])) == NULL)
		err_quit("hostname error for %s: %s", argv[1], hstrerror(h_errno));

	if ( (sp = getservbyname(argv[2], "tcp")) == NULL)
		err_quit("getservbyname error for %s", argv[2]);

	pptr = (struct in_addr **) hp->h_addr_list;
	for ( ; *pptr != NULL; pptr++) {
		sockfd = Socket(hp->h_addrtype, SOCK_STREAM, 0);

		if (hp->h_addrtype == AF_INET) {
			sa = (SA *) &servaddr;
			salen = sizeof(servaddr);
		} else if (hp->h_addrtype == AF_INET6) {
			sa = (SA *) &servaddr6;
			salen = sizeof(servaddr6);
		} else
			err_quit("unknown addrtype %d", hp->h_addrtype);

		bzero(sa, salen);
		sa->sa_family = hp->h_addrtype;
		sock_set_port(sa, salen, sp->s_port);
		sock_set_addr(sa, salen, *pptr);

		printf("trying %s\n", Sock_ntop(sa, salen));

		if (connect(sockfd, sa, salen) == 0)
			break;		/* success */
		err_ret("connect error");
		close(sockfd);
	}
	if (*pptr == NULL)
		err_quit("unable to connect");

	while ( (n = Read(sockfd, recvline, MAXLINE)) > 0) {
		recvline[n] = 0;	/* null terminate */
		Fputs(recvline, stdout);
	}
	exit(0);
}