嵌入式 hi3518平台获取网关

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</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 !
");
            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 !
");
            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	");
        fprintf(stdout,"%s	", tempBuf);

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

        /* Print Interface Name*/
        fprintf(stdout,"%s	", rtInfo->ifName);

        /* Print genmask address */
        if(rtInfo->genmask != 0)
            strcpy(tempBuf, (char *)inet_ntoa(rtInfo->genmask));
        else
            sprintf(tempBuf,"0.0.0.0	");

        fprintf(stdout,"%s	", tempBuf);

        /* Print Source address */
        if(rtInfo->srcAddr != 0)
            strcpy(tempBuf, (char *)inet_ntoa(rtInfo->srcAddr));
        else
            sprintf(tempBuf,"0.0.0.0	");
        fprintf(stdout,"%s
", 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
", (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 !
");
        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...
");
        close(sock);
        return -1;
    }

    /* Read the response */
    if((len = Joseph_ReadNlSock(sock, msgBuf, msgSeq, getpid())) < 0)
    {
        printf("Read From Socket Failed...
");
        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	Gateway	Interface	Source
");

    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
", gateway);
        sleep(1);
    }

    return 0;
}
</span></span>