Linux下通過ioctl系統調用來擷取和設定網絡資訊

#include <stdio.h> 

#include <stdlib.h> 

#include <string.h> 

#include <unistd.h> 

#include <sys/ioctl.h> 

#include <net/if.h> 

#include <arpa/inet.h> 

#include <linux/netlink.h> 

#include <linux/rtnetlink.h> 

// 擷取IP位址，子網路遮罩，MAC位址 

int GetLocalNetInfo( 

    const char* lpszEth, 

    char* szIpAddr, 

    char* szNetmask, 

    char* szMacAddr 

) 

{ 

    int ret = 0; 

    struct ifreq req; 

    struct sockaddr_in* host = NULL; 

    int sockfd = socket(AF_INET, SOCK_DGRAM, 0); 

    if ( -1 == sockfd ) 

    { 

        return -1; 

    } 

    bzero(&req, sizeof(struct ifreq)); 

    strcpy(req.ifr_name, lpszEth); 

    if ( ioctl(sockfd, SIOCGIFADDR, &req) >= 0 ) 

        host = (struct sockaddr_in*)&req.ifr_addr; 

        strcpy(szIpAddr, inet_ntoa(host->sin_addr)); 

    else 

        ret = -1; 

    if ( ioctl(sockfd, SIOCGIFNETMASK, &req) >= 0 ) 

        strcpy(szNetmask, inet_ntoa(host->sin_addr)); 

    if ( ioctl(sockfd, SIOCGIFHWADDR, &req) >= 0 ) 

        sprintf( 

            szMacAddr, "%02x:%02x:%02x:%02x:%02x:%02x", 

            (unsigned char)req.ifr_hwaddr.sa_data[0], 

            (unsigned char)req.ifr_hwaddr.sa_data[1], 

            (unsigned char)req.ifr_hwaddr.sa_data[2], 

            (unsigned char)req.ifr_hwaddr.sa_data[3], 

            (unsigned char)req.ifr_hwaddr.sa_data[4], 

            (unsigned char)req.ifr_hwaddr.sa_data[5] 

        ); 

    if ( sockfd != -1 ) 

        close(sockfd); 

        sockfd = -1; 

    return ret; 

} 

// ------------------------------------------------------ 

#define BUFSIZE 8192 

struct route_info  

    char ifName[IF_NAMESIZE]; 

    u_int gateWay; 

    u_int srcAddr; 

    u_int dstAddr; 

}; 

static int ReadNlSock( 

    int sockFd, 

    char* bufPtr, 

    int seqNum, 

    int pId 

    struct nlmsghdr* nlHdr = NULL; 

    int readLen = 0, msgLen = 0; 

    while (true) 

        if ( (readLen = recv(sockFd, bufPtr, BUFSIZE - msgLen, 0)) < 0 ) 

        { 

            return -1; 

        } 

        nlHdr = (struct nlmsghdr *)bufPtr; 

        if ( (NLMSG_OK(nlHdr, (unsigned int)readLen) == 0) 

                || (nlHdr->nlmsg_type == NLMSG_ERROR) ) 

        if ( nlHdr->nlmsg_type == NLMSG_DONE ) 

            break; 

        else 

            bufPtr += readLen; 

            msgLen += readLen; 

        if ( (nlHdr->nlmsg_flags & NLM_F_MULTI) == 0 ) 

        if ( (nlHdr->nlmsg_seq != (unsigned int)seqNum) 

                || (nlHdr->nlmsg_pid != (unsigned int)pId) ) 

    return msgLen; 

static int ParseRoutes( 

    struct nlmsghdr* nlHdr, 

    struct route_info* rtInfo, 

    char* default_gateway 

    int rtLen = 0; 

    struct in_addr dst; 

    struct in_addr gate; 

    struct rtmsg* rtMsg = NULL; 

    struct rtattr* rtAttr = NULL; 

    rtMsg = (struct rtmsg*)NLMSG_DATA(nlHdr); 

    if ( (rtMsg->rtm_family != AF_INET) 

            || (rtMsg->rtm_table != RT_TABLE_MAIN) ) 

    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); 

        case RTA_GATEWAY: 

            rtInfo->gateWay = *(u_int*)RTA_DATA(rtAttr); 

        case RTA_PREFSRC: 

            rtInfo->srcAddr = *(u_int*)RTA_DATA(rtAttr); 

        case RTA_DST: 

            rtInfo->dstAddr = *(u_int*)RTA_DATA(rtAttr); 

    dst.s_addr = rtInfo->dstAddr; 

    if (strstr((char*)inet_ntoa(dst), "0.0.0.0")) 

        gate.s_addr = rtInfo->gateWay; 

        strcpy(default_gateway, (char*)inet_ntoa(gate)); 

    return 0; 

// 擷取預設網關 

int GetDefaultGateway( 

    char* szDefaultGateway 

    static char szGatewayTemp[32] = {0}; 

    static char msgBuf[BUFSIZE] = {0}; 

    static struct route_info ri; 

    int ret = -1; 

    struct nlmsghdr* nlMsg = NULL; 

    struct route_info* rtInfo = &ri; 

    int len = 0, msgSeq = 0; 

    int sock = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_ROUTE); 

    if ( -1 == sock ) 

        goto END; 

    nlMsg = (struct nlmsghdr*)msgBuf; 

    rtMsg = (struct rtmsg*)NLMSG_DATA(nlMsg); 

    nlMsg->nlmsg_len = NLMSG_LENGTH(sizeof(struct rtmsg)); 

    nlMsg->nlmsg_type = RTM_GETROUTE; 

    nlMsg->nlmsg_flags = NLM_F_DUMP | NLM_F_REQUEST; 

    nlMsg->nlmsg_seq = msgSeq++; 

    nlMsg->nlmsg_pid = getpid(); 

    if ( send(sock, nlMsg, nlMsg->nlmsg_len, 0) < 0 ) 

    if ( (len = ReadNlSock(sock, msgBuf, msgSeq, getpid())) < 0 ) 

    if ( rtInfo != NULL ) 

        for ( ; NLMSG_OK(nlMsg, (unsigned int)len); nlMsg = NLMSG_NEXT(nlMsg, len) ) 

            memset(szGatewayTemp, 0, 64); 

            memset(rtInfo, 0, sizeof(struct route_info)); 

            if ( 0 == ParseRoutes(nlMsg, rtInfo, szGatewayTemp) ) 

            { 

                if ( strcmp(rtInfo->ifName, lpszEth) == 0 

                        && strcmp(szGatewayTemp, "0.0.0.0") != 0 

                        && strlen(szGatewayTemp) > 0 ) 

                { 

                    strcpy(szDefaultGateway, szGatewayTemp); 

                    ret = 0; 

                }  

            } 

END: 

    if ( sock != -1 ) 

        close(sock); 

        sock = -1; 

// 設定IP位址和子網路遮罩 

int SetLocalNetInfo( 

    const char* lpszIpAddr, 

    const char* lpszNetmask 

    host = (struct sockaddr_in*)&req.ifr_addr; 

    host->sin_family = AF_INET; 

    if ( 1 != inet_pton(AF_INET, lpszIpAddr, &(host->sin_addr)) ) 

    if ( ioctl(sockfd, SIOCSIFADDR, &req) < 0 ) 

    if ( 1 != inet_pton(AF_INET, lpszNetmask, &(host->sin_addr)) ) 

    if ( ioctl(sockfd, SIOCSIFNETMASK, &req) < 0 ) 

        goto END; 

    ret = 0; 

// 設定指定網口的mtu值 

int SetMTU(const char* lpszEth, unsigned int mtu) 

    struct ifreq ifr; 

    strcpy(ifr.ifr_name, lpszEth); 

    ifr.ifr_ifru.ifru_mtu = mtu; 

    if ( ioctl(sockfd, SIOCSIFMTU, &ifr) < 0 ) 

// 關閉指定網口 

int SetIfDown(const char* lpszEth) 

    if ( ioctl(sockfd, SIOCGIFFLAGS, &ifr) < 0 ) 

    ifr.ifr_flags &= ~IFF_UP; 

    if ( ioctl(sockfd, SIOCSIFFLAGS, &ifr) < 0 ) 

// 打開指定網口 

int SetIfUp(const char* lpszEth) 

    ifr.ifr_flags |= IFF_UP;