udpserv04.c

《Unix网络编程》的源代码的advio部分

#include	"unpifi.h"

void	mydg_echo(int, SA *, socklen_t);

int
main(int argc, char **argv)
{
	int					sockfd, family, port;
	const int			on = 1;
	pid_t				pid;
	socklen_t			salen;
	struct sockaddr		*sa, *wild;
	struct ifi_info		*ifi, *ifihead;

	if (argc == 2)
		sockfd = Udp_client(NULL, argv[1], (void **) &sa, &salen);
	else if (argc == 3)
		sockfd = Udp_client(argv[1], argv[2], (void **) &sa, &salen);
	else
		err_quit("usage: udpserv04 [ <host> ] <service or port>");
	family = sa->sa_family;
	port = sock_get_port(sa, salen);
	Close(sockfd);		/* we just want family, port, salen */

	for (ifihead = ifi = Get_ifi_info(family, 1);
		 ifi != NULL; ifi = ifi->ifi_next) {

			/*4bind unicast address */
		sockfd = Socket(family, SOCK_DGRAM, 0);
		Setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on));

		sock_set_port(ifi->ifi_addr, salen, port);
		Bind(sockfd, ifi->ifi_addr, salen);
		printf("bound %s\n", Sock_ntop(ifi->ifi_addr, salen));

		if ( (pid = Fork()) == 0) {		/* child */
			mydg_echo(sockfd, ifi->ifi_addr, salen);
			exit(0);		/* never executed */
		}

		if (ifi->ifi_flags & IFF_BROADCAST) {
				/* 4try to bind broadcast address */
			sockfd = Socket(family, SOCK_DGRAM, 0);
			Setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on));

			sock_set_port(ifi->ifi_brdaddr, salen, port);
			if (bind(sockfd, ifi->ifi_brdaddr, salen) < 0) {
				if (errno == EADDRINUSE) {
					printf("EADDRINUSE: %s\n",
						   Sock_ntop(ifi->ifi_brdaddr, salen));
					continue;
				} else
					err_sys("bind error for %s",
							Sock_ntop(ifi->ifi_brdaddr, salen));
			}
			printf("bound %s\n", Sock_ntop(ifi->ifi_brdaddr, salen));

			if ( (pid = Fork()) == 0) {		/* child */
				mydg_echo(sockfd, ifi->ifi_brdaddr, salen);
				exit(0);		/* never executed */
			}
		}
	}

		/* 4bind wildcard address */
	sockfd = Socket(family, SOCK_DGRAM, 0);
	Setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on));

	wild = Malloc(salen);
	memcpy(wild, sa, salen);	/* copy family and port */
	sock_set_wild(wild, salen);

	Bind(sockfd, wild, salen);
	printf("bound %s\n", Sock_ntop(wild, salen));

	if ( (pid = Fork()) == 0) {		/* child */
		mydg_echo(sockfd, wild, salen);
		exit(0);		/* never executed */
	}
	exit(0);
}

void
mydg_echo(int sockfd, SA *myaddr, socklen_t salen)
{
	int			n;
	char		mesg[MAXLINE];
	socklen_t	len;
	struct sockaddr *cli;

	cli = Malloc(salen);

	for ( ; ; ) {
		len = salen;
		n = Recvfrom(sockfd, mesg, MAXLINE, 0, cli, &len);
		printf("child %d, datagram from %s",
			   getpid(), Sock_ntop(cli, len));
		printf(", to %s\n", Sock_ntop(myaddr, salen));

		Sendto(sockfd, mesg, n, 0, cli, salen);
	}
}