嵌入式 hi3518平台获取网关

</pre><pre code_snippet_id="495447" snippet_file_name="blog_20141024_1_7065081" name="code" class="html">/********************************** (C) COPYRIGHT *******************************/

 * File Name          : get_gw.c  
 * Author             : skdkjzz  
 * Date               : 2014/08/07  
 * Description        : linux下获取网卡信息  
 *********************************************************************************/  

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <asm/types.h>
#include <netinet/ether.h>
#include <netinet/in.h>
#include <net/if.h>
#include <stdio.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <linux/netlink.h>
#include <linux/rtnetlink.h>
#include <sys/types.h>

#define JSOEPH_NET_RMSG_BUFSIZE 8192

typedef struct route_info{
	u_int dstAddr;
	u_int srcAddr;
	u_int gateWay;
	u_int genmask;
	char ifName[IF_NAMESIZE];
}JOSEPH_ROUTE_INFO;

#ifdef JOSEPH_CAT_ENUM
/* Routing message attributes */
enum rtattr_type_t {
	RTA_UNSPEC,
	RTA_DST,
	RTA_SRC,
	RTA_IIF,
	RTA_OIF,
	RTA_GATEWAY,
	RTA_PRIORITY,
	RTA_PREFSRC,
	RTA_METRICS,
	RTA_MULTIPATH,
	RTA_PROTOINFO, /* no longer used */
	RTA_FLOW,
	RTA_CACHEINFO,
	RTA_SESSION, /* no longer used */
	RTA_MP_ALGO, /* no longer used */
	RTA_TABLE,
	RTA_MARK,
	__RTA_MAX
};
#endif

int Joseph_ReadNlSock(int sockFd, char *bufPtr, int seqNum, int pId)
{
	struct nlmsghdr *nlHdr;
	int readLen = 0, msgLen = 0;

	do
	{
		/* Recieve response from the kernel */
		if((readLen = recv(sockFd, bufPtr, JSOEPH_NET_RMSG_BUFSIZE - msgLen, 0)) < 0){
			printf("SOCK READ Error !\n");
			return -1;
		}

		nlHdr = (struct nlmsghdr *)bufPtr;

		/* Check if the header is valid */
		if((NLMSG_OK(nlHdr, readLen) == 0) || (nlHdr->nlmsg_type == NLMSG_ERROR))
		{
			printf("Error in recieved packet !\n");
			return -1;
		}

		/* Check if the its the last message */
		if(nlHdr->nlmsg_type == NLMSG_DONE) 
		{
			break;
		}
		else
		{
			/* Else move the pointer to buffer appropriately */
			bufPtr += readLen;
			msgLen += readLen;
		}

		/* Check if its a multi part message */
		if((nlHdr->nlmsg_flags & NLM_F_MULTI) == 0) 
		{
			/* return if its not */
			break;
		}
	} while((nlHdr->nlmsg_seq != seqNum) || (nlHdr->nlmsg_pid != pId));
	
	return msgLen;
}


/* For printing the routes. */
void Joseph_PrintRoute(struct route_info *rtInfo,char *if_name_in)
{
	char tempBuf[512];

	if(strcmp(rtInfo->ifName,if_name_in) == 0)
	{
		/* Print Destination address */
		if(rtInfo->dstAddr != 0)
			strcpy(tempBuf, (char *)inet_ntoa(rtInfo->dstAddr));
		else
			sprintf(tempBuf,"0.0.0.0\t");
		fprintf(stdout,"%s\t", tempBuf);

		/* Print Gateway address */
		if(rtInfo->gateWay != 0)
			strcpy(tempBuf, (char *)inet_ntoa(rtInfo->gateWay));
		else
			sprintf(tempBuf,"0.0.0.0\t");
		fprintf(stdout,"%s\t", tempBuf);

		/* Print Interface Name*/
		fprintf(stdout,"%s\t", rtInfo->ifName);
		
		/* Print genmask address */
		if(rtInfo->genmask != 0)
			strcpy(tempBuf, (char *)inet_ntoa(rtInfo->genmask));
		else
			sprintf(tempBuf,"0.0.0.0\t");
		
		fprintf(stdout,"%s\t", tempBuf);

		/* Print Source address */
		if(rtInfo->srcAddr != 0)
			strcpy(tempBuf, (char *)inet_ntoa(rtInfo->srcAddr));
		else
			sprintf(tempBuf,"0.0.0.0\t");
		fprintf(stdout,"%s\n", tempBuf);
	}

}

/* For parsing the route info returned */
int Joseph_ParseRoutes(struct nlmsghdr *nlHdr, struct route_info *rtInfo,char *gateway,char *if_name_in)
{
	struct rtmsg *rtMsg;
	struct rtattr *rtAttr;
	int rtLen;
	char *tempBuf = NULL;

	tempBuf = (char *)malloc(100);
	rtMsg = (struct rtmsg *)NLMSG_DATA(nlHdr);

	/* If the route is not for AF_INET or does not belong to main routing table then return. */
	if((rtMsg->rtm_family != AF_INET) || (rtMsg->rtm_table != RT_TABLE_MAIN))
	{
		free(tempBuf);
		tempBuf = NULL;
		return -1;
	}


	/* get the rtattr field */
	rtAttr = (struct rtattr *)RTM_RTA(rtMsg);
	rtLen = RTM_PAYLOAD(nlHdr);
	
	for(;RTA_OK(rtAttr,rtLen);rtAttr = RTA_NEXT(rtAttr,rtLen))
	{
		switch(rtAttr->rta_type) 
		{
			case RTA_OIF:
				if_indextoname(*(int *)RTA_DATA(rtAttr), rtInfo->ifName);
				break;
			case RTA_GATEWAY:
				rtInfo->gateWay = *(u_int *)RTA_DATA(rtAttr);
				break;
			case RTA_PREFSRC:
				rtInfo->srcAddr = *(u_int *)RTA_DATA(rtAttr);
				break;
			case RTA_DST:
				rtInfo->dstAddr = *(u_int *)RTA_DATA(rtAttr);
				break;
		}
	}
	
	//printf("%s\n", (char *)inet_ntoa(rtInfo->dstAddr));
	//ADDED BY BOB - ALSO COMMENTED Joseph_PrintRoute

	if (strstr((char *)inet_ntoa(rtInfo->dstAddr), "0.0.0.0"))
	{
		sprintf(gateway,"%s",(char *)inet_ntoa(rtInfo->gateWay));		
	}

	Joseph_PrintRoute(rtInfo,if_name_in);

	free(tempBuf);
	tempBuf = NULL;

	return 0;
}

int Joseph_Get_Gateway(char *gateway,char *if_name)
{
	struct nlmsghdr *nlMsg;
	struct rtmsg *rtMsg;
	struct route_info *rtInfo;
	char msgBuf[JSOEPH_NET_RMSG_BUFSIZE];

	int sock, len, msgSeq = 0;
	char buff[1024];

	if(strlen(if_name) == 0 || gateway == NULL)
	{
		return -1;
	}
	
	/* Create Socket */
	if((sock = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_ROUTE)) < 0)
	{
		printf("Socket Creation Error !\n");
		return -1;
	}
		
	/* Initialize the buffer */
	memset(msgBuf, 0, JSOEPH_NET_RMSG_BUFSIZE);

	/* point the header and the msg structure pointers into the buffer */
	nlMsg = (struct nlmsghdr *)msgBuf;
	rtMsg = (struct rtmsg *)NLMSG_DATA(nlMsg);

	/* Fill in the nlmsg header*/
	nlMsg->nlmsg_len = NLMSG_LENGTH(sizeof(struct rtmsg)); // Length of message.
	nlMsg->nlmsg_type = RTM_GETROUTE; // Get the routes from kernel routing table .
	nlMsg->nlmsg_flags = NLM_F_DUMP | NLM_F_REQUEST; // The message is a request for dump.
	nlMsg->nlmsg_seq = msgSeq++; // Sequence of the message packet.
	nlMsg->nlmsg_pid = getpid(); // PID of process sending the request.


	/* Send the request */
	if(send(sock, nlMsg, nlMsg->nlmsg_len, 0) < 0)
	{
		printf("Write To Socket Failed...\n");
		close(sock);
		return -1;
	}

	/* Read the response */
	if((len = Joseph_ReadNlSock(sock, msgBuf, msgSeq, getpid())) < 0) 
	{
		printf("Read From Socket Failed...\n");
		close(sock);
		return -1;
	}
	
	/* Parse and print the response */
	rtInfo = (struct route_info *)malloc(sizeof(struct route_info));
	
	/* THIS IS THE NETTSTAT -RL code I commented out the printing here and in parse routes */
	//fprintf(stdout, "Destination\tGateway\tInterface\tSource\n");

	for( ; NLMSG_OK(nlMsg,len); nlMsg = NLMSG_NEXT(nlMsg,len))
	{
		memset(rtInfo, 0, sizeof(struct route_info));
		Joseph_ParseRoutes(nlMsg,rtInfo,gateway,if_name);
	}
	
	free(rtInfo);
	rtInfo = NULL;
	close(sock);

	return 0;
}


int main(int argc,char *argv[])
{
	int itertion = 0;
	char gateway[16]={0};
	int Qy_Ret = 0;
	
	if(argc != 2)
	{
		return -1;
	}
	
	while(itertion < 30)
	{
	
		Qy_Ret = Joseph_Get_Gateway(gateway,argv[1]);
		if(Qy_Ret <0)
		{
			return -1;
		}
		itertion++;
		printf("Gateway:%s\n", gateway);
		sleep(1);
	}
	
	return 0;
}
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