linux 下C语言实现 读取网卡速度

这几天要写一个监控之类东东，其中网卡一项要计算利用率，那就要取得网卡本身速度才能计算出来，本来想用perl实现，但发现网上没有现成的东东，后来几经辗转，最后想起ethtool能取到，就参考了此源码，贴出来供大家以后有个思路吧，

有时间再转成perl的:)

直接编译命令：gcc -p -g  getNet.c && gcc -o getNet getNet.c && ./getNet eth0

源码如下：

 

// filename: getNet.c// command sample: ./getNet eth0// compile command: gcc -p -g  getNet.c && gcc -o getNet getNet.c#include <string.h>#include <sys/ioctl.h>#include <string.h>#include <errno.h>#include <linux/sockios.h>#include <net/if.h>#include <stdio.h>#include <stdint.h>#include <stddef.h>#include <stdlib.h>#include <sys/stat.h>#include <sys/types.h>#include <sys/socket.h>#ifndef SIOCETHTOOL#define SIOCETHTOOL     0x8946#endif#ifndef ARRAY_SIZE#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))#endif/* CMDs currently supported */#define ETHTOOL_GSET        0x00000001 /* Get settings. */#define ETHTOOL_SSET        0x00000002 /* Set settings. *//* hack, so we may include kernel's ethtool.h *///typedef unsigned long long __u64;typedef __uint32_t __u32;       /* ditto */typedef __uint16_t __u16;       /* ditto */typedef __uint8_t __u8;         /* ditto *//* The forced speed, 10Mb, 100Mb, gigabit, 2.5Gb, 10GbE. */#define SPEED_10        10#define SPEED_100       100#define SPEED_1000      1000#define SPEED_2500      2500#define SPEED_10000     10000/* This should work for both 32 and 64 bit userland. */struct ethtool_cmd {        __u32   cmd;        __u32   supported;      /* Features this interface supports */        __u32   advertising;    /* Features this interface advertises */        __u16   speed;          /* The forced speed, 10Mb, 100Mb, gigabit */        __u8    duplex;         /* Duplex, half or full */        __u8    port;           /* Which connector port */        __u8    phy_address;        __u8    transceiver;    /* Which transceiver to use */        __u8    autoneg;        /* Enable or disable autonegotiation */        __u32   maxtxpkt;       /* Tx pkts before generating tx int */        __u32   maxrxpkt;       /* Rx pkts before generating rx int */        __u32   reserved[4];};int main(int argc, char *argp[]){    if(argc != 2)    {        fprintf(stdout, "parameter is erro . usage : getNet ethXX!\n");        return 1;    }    char *devname;    devname = argp[1] ; // 取得网卡名    //devname = "eth0" ; // 取得网卡名/* http://topic.csdn.net/u/20070104/12/e57086ff-1a48-477b-b672-91e4ba3b6da4.html    ifreq结构定义在/usr/include\net/if.h，用来配置ip地址，激活接口，配置MTU等接口信息的。    其中包含了一个接口的名字和具体内容——（是个共用体，有可能是IP地址，广播地址，子网掩码，MAC号，MTU或其他内容）。    ifreq包含在ifconf结构中。而ifconf结构通常是用来保存所有接口的信息的。*/    struct ifreq ifr, *ifrp;  // 接口请求结构    int fd;   // to  access socket  通过socket访问网卡的 文件描述符号fd    /* Setup our control structures. */    memset(&ifr, 0, sizeof(ifr));    strcpy(ifr.ifr_name, devname);    /* Open control socket. */    fd = socket(AF_INET, SOCK_DGRAM, 0);    if (fd < 0) {        perror("Cannot get control socket");        return 70;    }        int err;    struct ethtool_cmd ep;    //fprintf(stdout, "Settings for %s:\n", devname);    ep.cmd = ETHTOOL_GSET; // ethtool-copy.h:380:#define ETHTOOL_GSET         0x00000001 /* Get settings. */    ifr.ifr_data = (caddr_t)&ep;  //   caddr_t 是void类型，而这句话是什么意思    err = ioctl(fd, SIOCETHTOOL, &ifr);  //  int ioctl(int handle, int cmd,[int *argdx, int argcx]);    if (err != 0) { // 如果出错退出;         printf(" ioctl is erro .\n");        return -1;    }    // ===========  输出 网卡速度；============    fprintf(stdout, "%s Speed: ", devname );    switch (ep.speed) {    case SPEED_10:        fprintf(stdout, "10Mb/s\n");        break;    case SPEED_100:        fprintf(stdout, "100Mb/s\n");        break;    case SPEED_1000:        fprintf(stdout, "1000Mb/s\n");        break;    case SPEED_2500:        fprintf(stdout, "2500Mb/s\n");        break;    case SPEED_10000:        fprintf(stdout, "10000Mb/s\n");        break;    default:        fprintf(stdout, "Unknown! (%i)\n", ep.speed);        break;    };    return 0; }