sock 프로그래밍 학습 2

#include "apue.h"
#include <errno.h>
#include <sys/socket.h>

int
initserver(int type, const struct sockaddr *addr, socklen_t alen,
  int qlen)
{
    int fd;
    int err = 0;

    if ((fd = socket(addr->sa_family, type, 0)) < 0)
        return(-1);
    if (bind(fd, addr, alen) < 0) {
        err = errno;
        goto errout;
    }
    if (type == SOCK_STREAM || type == SOCK_SEQPACKET) {
        if (listen(fd, qlen) < 0) {
            err = errno;
            goto errout;
        }
    }
    return(fd);

errout:
    close(fd);
    errno = err;
    return(-1);
}

#ifndef HOST_NAME_MAX
#define HOST_NAME_MAX 256
#endif

extern int initserver(int, const struct sockaddr*, socklen_t, int);
extern void daemonize(const char *cmd);
void serve(int sockfd)
{
	int clfd;
	FILE *fp;
	char buf[BUFLEN];
	while(1)
	{
		clfd = accept(sockfd, NULL, NULL);
		if(clfd < 0)
		{
			syslog(LOG_ERR, "ruptimed: accept error: %s", strerror(errno));
			exit(1);
		}
		if((fp = popen("/usr/bin/uptime", "r")) == NULL)
		{
			sprintf(buf, "error: %s
", strerror(errno));
			send(clfd, buf, strlen(buf), 0);
		}
		else
		{
			while(fgets(buf, BUFLEN, fp)!= NULL)
				send(clfd, buf, strlen(buf), 0);
			pclose(fp);
		}
		close(clfd);
	}
}

int main()
{
	struct addrinfo *ailist, *aip;
	struct addrinfo hint;
	int	   sockfd, err;

	int    n;
	char   *host;

#ifdef _SC_HOST_NAME_MAX
	n = sysconf(_SC_HOST_NAME_MAX);
	if(n < 0)
#endif
	n = HOST_NAME_MAX;
	host = malloc(n);
	if(host == NULL)
	{
		printf("malloc error
");
		exit(-1);
	}
	if(gethostname(host, n) < 0)
	{
		printf("gethostname error
");
		exit(-1);
	}
	daemonize("ruptimed");
	hint.ai_flags = AI_PASSIVE;
	hint.ai_family = 0;
	hint.ai_socktype = SOCK_STREAM;
	hint.ai_protocol = 0;
	hint.ai_addrlen = 0;
	hint.ai_addr = 0;
	hint.ai_canonname = 0;
	hint.ai_next = NULL;

	if((err = getaddrinfo(host, "ruptimed", &hint, &ailist)) != 0)
	{
		syslog(LOG_ERR, "ruptimed: getaddrinfo error: %s", gai_strerror(err));
		exit(1);
	}
	for(aip = ailist; aip != NULL; aip = aip->ai_next)
	{
		if((sockfd = initserver(SOCK_STREAM, aip->ai_addr, aip->ai_addrlen, QLEN)) >= 0)
		{
			serve(sockfd);
			exit(0);
		}
	}
	exit(1);
}

void print_uptime(int sockfd)
{
	int		n;
	char	buf[BUFLEN];

	while((n = recv(sockfd, buf, BUFLEN, 0)) > 0)
	{
		write(STDOUT_FILENO, buf, n);
	}
	if(n < 0)
	{
		printf("recv error
");
		exit(-1);
	}
}

int main(int argc, char *argv[])
{
	struct addrinfo *ailist, *aip;
	struct addrinfo hint;
	int	   sockfd, err;

	if(argc != 2)
	{
		printf("usage: ruptime hostname
");
		exit(-1);
	}

	hint.ai_flags = 0;
	hint.ai_family = 0;
	hint.ai_socktype = SOCK_STREAM;
	hint.ai_protocol = 0;
	hint.ai_addrlen = 0;
	hint.ai_addr = NULL;
	hint.ai_canonname = NULL;
	hint.ai_next = NULL;
	
	if((err =getaddrinfo(argv[1],"ruptimed", &hint, &ailist)) != 0)
	{
		printf("getaddrinfo error: %s 
", gai_strerror(err));
		exit(-1);
	}
	for(aip = ailist; aip != NULL; aip = aip->ai_next)
	{
		if((sockfd = socket(aip->ai_family, SOCK_STREAM, 0)) < 0)
		{
			err = errno;
			continue;
		}
		if(connect_retry(sockfd, aip->ai_addr, aip->ai_addrlen, 1) < 0)
			err = errno;
		else
		{
			print_uptime(sockfd);
			exit(0);
		}
	}
	fprintf(stderr, "can't connect to %s: %s
", argv[1], strerror(err));
	exit(1);
}

serve(int sockfd)
{
    int         n;
    socklen_t   alen;
    FILE        *fp;
    char        buf[BUFLEN];
    char        abuf[MAXADDRLEN];

    for (;;) {
        alen = MAXADDRLEN;
        if ((n = recvfrom(sockfd, buf, BUFLEN, 0,
          (struct sockaddr *)abuf, &alen)) < 0) {
            syslog(LOG_ERR, "ruptimed: recvfrom error: %s",
              strerror(errno));
            exit(1);
        }
        if ((fp = popen("/usr/bin/uptime", "r")) == NULL) {
            sprintf(buf, "error: %s
", strerror(errno));
            sendto(sockfd, buf, strlen(buf), 0,
              (struct sockaddr *)abuf, alen);
        } else {
            if (fgets(buf, BUFLEN, fp) != NULL)
                sendto(sockfd, buf, strlen(buf), 0,

                  (struct sockaddr *)abuf, alen);
            pclose(fp);
        }

    }

}

print_uptime(int sockfd, struct addrinfo *aip)
{
    int     n;
    char    buf[BUFLEN];

    buf[0] = 0;
    if (sendto(sockfd, buf, 1, 0, aip->ai_addr, aip->ai_addrlen) < 0)
        err_sys("sendto error");
    alarm(TIMEOUT);
    if ((n = recvfrom(sockfd, buf, BUFLEN, 0, NULL, NULL)) < 0) {
        if (errno != EINTR)
            alarm(0);
        err_sys("recv error");
    }
    alarm(0);
    write(STDOUT_FILENO, buf, n);
}