chosts.c

linux/unix下c/s形式的资源监视,客户端负责搜集机器,再传送到服务端.

/* 
 * List all the hosts in this cluster with the help of 
 * /proc/cluster directory.
 *
 * Copyright (c) 2004, by:      Jian Shen
 *    All rights reserved.      Peking University, China
 *                             <[e-mail]>
 *
 * This file may be used subject to the terms and conditions of the
 * GNU Library General Public License Version 2, or any later version
 * at your option, as published by the Free Software Foundation.
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Library General Public License for more details.
 *
 */
#include <sys/types.h>
#include <dirent.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <arpa/inet.h>
#include <netdb.h>

void print_host(char* host_ip)
{
    long hostname;
    struct hostent *hinfo;
                       
	hostname = inet_addr(host_ip);
	hinfo = gethostbyaddr((char *)&hostname, sizeof(long), AF_INET);

	if(hinfo != NULL)
		printf("%s\n", hinfo->h_name);
	else
		printf("%s\n", host_ip);
}

void help()
{
	printf("\nCluster load monitor like top.\n");
	printf("no arguments is needed.\n");
	printf("report bugs to <[e-mail]>.\n");
	printf("\n");
}

int main(int argc, char* argv[])
{
	DIR *dp;
	struct dirent *dirp;

	if(argc != 1) {
		help();
		exit(1);
	}

	if((dp = opendir("/proc/cluster")) == NULL) {
		fprintf(stderr, "Failed to open /proc/cluster!\n");
		exit(1);
	}

	printf("current hosts: \n");
	while((dirp = readdir(dp)) != NULL) {
		if(strcmp(dirp->d_name, ".") == 0)
			continue;

		if(strcmp(dirp->d_name, "..") == 0)
			continue;

		print_host(dirp->d_name);
	}

	closedir(dp);
	
	return 0;
}