linux系统下获取IP，MAC，子网掩码，网关

添加对应头文件

#include<stdio.h>
#include <cstdlib>
#include<string.h>
#include<unistd.h>
#include <fstream>
#include<iostream>
#include <net/if.h>
#include <sys/ioctl.h>
#include <arpa/inet.h>
#include <errno.h>
#include <linux/rtnetlink.h>
#include <stdlib.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/utsname.h>
#include <limits.h>
#include <ctype.h>
#include <linux/sockios.h>

获取IP和子网掩码

int getLocalInfo(char IP[],char Mask[])
{
   int fd;
   int interfaceNum = 0;
   struct ifreq buf[16];
   struct ifconf ifc;
   struct ifreq ifrcopy;
   char mac[16] = {0};
   char ip[32] = {0};
   char broadAddr[32] = {0};
   char subnetMask[32] = {0};
   if ((fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0)
   {
      perror("socket");
      close(fd);
      return -1;
   }
   ifc.ifc_len = sizeof(buf);
   ifc.ifc_buf = (caddr_t)buf;
   if (!ioctl(fd, SIOCGIFCONF, (char *)&ifc))
   {
      interfaceNum = ifc.ifc_len / sizeof(struct ifreq);
      printf("interface num = %d\n", interfaceNum);
      while (interfaceNum-- > 0)
      {
             printf("\ndevice name: %s\n", buf[interfaceNum].ifr_name);
             //ignore the interface that not up or not runing
             ifrcopy = buf[interfaceNum];
             if (ioctl(fd, SIOCGIFFLAGS, &ifrcopy))
             {
                printf("ioctl: %s [%s:%d]\n", strerror(errno), __FILE__, __LINE__);
                close(fd);
                return -1;
             }
             //get the mac of this interface
             if (!ioctl(fd, SIOCGIFHWADDR, (char *)(&buf[interfaceNum])))
             {
                memset(mac, 0, sizeof(mac));
                snprintf(mac, sizeof(mac), "%02x%02x%02x%02x%02x%02x",
                                (unsigned char)buf[interfaceNum].ifr_hwaddr.sa_data[0],
                                (unsigned char)buf[interfaceNum].ifr_hwaddr.sa_data[1],
                                (unsigned char)buf[interfaceNum].ifr_hwaddr.sa_data[2],
                                (unsigned char)buf[interfaceNum].ifr_hwaddr.sa_data[3],
                                (unsigned char)buf[interfaceNum].ifr_hwaddr.sa_data[4],
                                (unsigned char)buf[interfaceNum].ifr_hwaddr.sa_data[5]);
                printf("device mac: %s\n", mac);
             }
            else
            {
                printf("ioctl: %s [%s:%d]\n", strerror(errno), __FILE__, __LINE__);
                close(fd);
                return -1;
            }
            //get the IP of this interface
            if (!ioctl(fd, SIOCGIFADDR, (char *)&buf[interfaceNum]))
            {
                snprintf(ip, sizeof(ip), "%s",
                            (char *)inet_ntoa(((struct sockaddr_in *)&(buf[interfaceNum].ifr_addr))->sin_addr));
                printf("device ip: %s\n", ip);
            }
            else
            {
                printf("ioctl: %s [%s:%d]\n", strerror(errno), __FILE__, __LINE__);
                close(fd);
                return -1;
            }
            //get the broad address of this interface
            if (!ioctl(fd, SIOCGIFBRDADDR, &buf[interfaceNum]))
            {
                snprintf(broadAddr, sizeof(broadAddr), "%s",
                            (char *)inet_ntoa(((struct sockaddr_in *)&(buf[interfaceNum].ifr_broadaddr))->sin_addr));
                printf("device broadAddr: %s\n", broadAddr);
            }
            else
            {
                printf("ioctl: %s [%s:%d]\n", strerror(errno), __FILE__, __LINE__);
                close(fd);
                return -1;
            }
            //get the subnet mask of this interface
            if (!ioctl(fd, SIOCGIFNETMASK, &buf[interfaceNum]))
            {
                snprintf(subnetMask, sizeof(subnetMask), "%s",
                            (char *)inet_ntoa(((struct sockaddr_in *)&(buf[interfaceNum].ifr_netmask))->sin_addr));
                printf("device subnetMask: %s\n", subnetMask);
            }
            else
            {
                printf("ioctl: %s [%s:%d]\n", strerror(errno), __FILE__, __LINE__);
                close(fd);
                return -1;
            }
        }
    }
    else
    {
        printf("ioctl: %s [%s:%d]\n", strerror(errno), __FILE__, __LINE__);
        close(fd);
        return -1;
    }
   strcpy(IP,ip);
   //strcpy(broad,broadAddr);
   strcpy(Mask,subnetMask);
   close(fd);
   return 0;
}

获取网关

int readNlSock(int sockFd, char *bufPtr, int seqNum, int pId)
{
	  struct nlmsghdr *nlHdr;
	  int readLen = 0, msgLen = 0;
	  do{
			if((readLen = recv(sockFd, bufPtr, BUFSIZE - msgLen, 0)) < 0)
			{
			  perror("SOCK READ: ");
			  return -1;
			}

			nlHdr = (struct nlmsghdr *)bufPtr;
			if((NLMSG_OK(nlHdr, readLen) == 0) || (nlHdr->nlmsg_type == NLMSG_ERROR))
			{
			  perror("Error in recieved packet");
			  return -1;
			}
			if(nlHdr->nlmsg_type == NLMSG_DONE)
			{
			  break;
			}
			else
			{

			  bufPtr += readLen;
			  msgLen += readLen;
			}
			if((nlHdr->nlmsg_flags & NLM_F_MULTI) == 0)
			{

			 break;
			}
	  } while((nlHdr->nlmsg_seq != seqNum) || (nlHdr->nlmsg_pid != pId));
	  return msgLen;
}

void parseRoutes(struct nlmsghdr *nlHdr, struct route_info *rtInfo,char gateway[])
{
	  struct rtmsg *rtMsg;
	  struct rtattr *rtAttr;
	  int rtLen;
	  char *tempBuf = NULL;
	  struct in_addr dst;
	  struct in_addr gate;
	  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))
	  return;

	  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;
	   }
	  }
	  dst.s_addr = rtInfo->dstAddr;
	  if (strstr((char *)inet_ntoa(dst), "0.0.0.0"))
	  {
		printf("oif:%s",rtInfo->ifName);
		gate.s_addr = rtInfo->gateWay;
		sprintf(gateway, (char *)inet_ntoa(gate));
		printf("%s\n",gateway);
		gate.s_addr = rtInfo->srcAddr;
		printf("src:%s\n",(char *)inet_ntoa(gate));
		gate.s_addr = rtInfo->dstAddr;
		printf("dst:%s\n",(char *)inet_ntoa(gate));
	  }
	  free(tempBuf);
	  return;
}

int get_gateway(char gateway[])
{
	 struct nlmsghdr *nlMsg;
	 struct rtmsg *rtMsg;
	 struct route_info *rtInfo;
	 char msgBuf[BUFSIZE];

	 int sock, len, msgSeq = 0;

	 if((sock = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_ROUTE)) < 0)
	 {
	  perror("Socket Creation: ");
	  return -1;
	 }
	 memset(msgBuf, 0, BUFSIZE);
	 nlMsg = (struct nlmsghdr *)msgBuf;
	 rtMsg = (struct rtmsg *)NLMSG_DATA(nlMsg);
	 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.
	 if(send(sock, nlMsg, nlMsg->nlmsg_len, 0) < 0){
	  printf("Write To Socket Failed…\n");
	  return -1;
	 }
	 if((len = readNlSock(sock, msgBuf, msgSeq, getpid())) < 0) {
	  printf("Read From Socket Failed…\n");
	  return -1;
	 }

	 rtInfo = (struct route_info *)malloc(sizeof(struct route_info));
	 for(;NLMSG_OK(nlMsg,len);nlMsg = NLMSG_NEXT(nlMsg,len)){
	  memset(rtInfo, 0, sizeof(struct route_info));
	  parseRoutes(nlMsg, rtInfo,gateway);
	 }
	 free(rtInfo);
	 close(sock);
	 return 0;
}