GetLocalIP的几种方法

2012-01-05 wcdj

方法1：getaddrinfo

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>// inet_ntop
#include <netdb.h>
#include <string.h>// bzero
#include <errno.h>

void GetSelfServerIP(char *pszIP)
{
	struct addrinfo *answer, hint, *curr;
	//char szIP[16];
	bzero(&hint, sizeof(hint));
	hint.ai_family = AF_INET;
	hint.ai_socktype = SOCK_STREAM;

	int iRet = 0;
	char szHostName[128] = {0};
	iRet = gethostname(szHostName, sizeof(szHostName));
	if (iRet != 0)
	{
		fprintf(stderr, "gethostname error! [%s]\n", strerror(errno));
		exit(1);
	}
	printf("hostname [%s]\n", szHostName);

	iRet = getaddrinfo(szHostName, NULL, &hint, &answer);
	if (iRet != 0)
	{
		fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(iRet));
		exit(1);
	}

	for (curr = answer; curr != NULL; curr = curr->ai_next)
	{
		inet_ntop(AF_INET, &(((struct sockaddr_in *)(curr->ai_addr))->sin_addr), pszIP, 16);
		//printf("%s\n", pszIP);
	}

	freeaddrinfo(answer);
}

int main(int argc, char **argv)
{ 
	char szIP[16] = {0};
	GetSelfServerIP(szIP);
	printf("IP [%s]\n", szIP);

	return 0;
}

方法2：ioctl

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <net/if.h>
#include <netdb.h>
#include <arpa/inet.h>
#include <sys/ioctl.h>


bool GetLocalIP(char * pszIPBuf)
{
	#define MAXINTERFACES 16 

	bool result = false;

	int fd = -1;
	int intrface = 0; 
	struct ifreq buf[MAXINTERFACES]; 
	struct ifconf ifc; 

	if ((fd = socket (AF_INET, SOCK_DGRAM, 0)) >= 0) 
	{ 
		ifc.ifc_len = sizeof buf; 
		ifc.ifc_buf = (caddr_t) buf; 
		if (!ioctl (fd, SIOCGIFCONF, (char *) &ifc)) 
		{ 
			//获取接口信息
			intrface = ifc.ifc_len / sizeof (struct ifreq); 
			//根据借口信息循环获取设备IP和MAC地址
			while (intrface-- > 0) 
			{     
				//获取设备名称
				//printf ("net device %s\n", buf[intrface].ifr_name); 

				if ( strstr(buf[intrface].ifr_name,"eth") != NULL )
				{
					//获取当前网卡的IP地址 
					if (!(ioctl (fd, SIOCGIFADDR, (char *) &buf[intrface]))) 
					{ 
						if ( inet_ntop(AF_INET,
									&(( (struct sockaddr_in*)(& (buf[intrface].ifr_addr) ))->sin_addr),
									pszIPBuf,16) )
						{
							return true;
						}
					}
				}
			}
		}

		close (fd); 
	}

	return result;
}


int main()
{
	char pszIPBuf[20] = {0};
	GetLocalIP(pszIPBuf);
	if (pszIPBuf[0] != '\0')
		printf("local IP [%s]\n", pszIPBuf);
	else
		printf("Get local IP error!\n");

	return 0;
}