前面写了一篇关于网络相关的文章：如何获取当前可用网口。
那么如何使用C语言直接操作网口？
比如读写IP地址、读写MAC地址等。
一、原理
主要通过系统用socket()、ioctl()、实现
int socket(int domain, int type, int protocol);
功能：
创建套接字
参数:
domain：
Name Purpose Man page
AF_UNIX, AF_LOCAL Local communication unix(7)
AF_INET IPv4 Internet protocols ip(7)
type：
SOCK_STREAM Provides sequenced, reliable, two-way, connection-based
byte streams. An out-of-band data transmission mecha‐
nism may be supported.
SOCK_DGRAM Supports datagrams (connectionless, unreliable messages
of a fixed maximum length).
protocol：
通常为0
返回值：
成功：新的套接字的文件描述符
失败：错误码，负值
int ioctl(int fd, unsigned long request, ...);
参数：
fd ：文件描述符
request：命令
... ：参数
其中网络用到的request定义头文件位于：
/usr/include/linux/sockios.h
/* Linux-specific socket ioctls */
#define SIOCINQ FIONREAD
#define SIOCOUTQ TIOCOUTQ /* output queue size (not sent + not acked) */
/* Routing table calls. */
#define SIOCADDRT 0x890B /* add routing table entry */
#define SIOCDELRT 0x890C /* delete routing table entry */
#define SIOCRTMSG 0x890D /* call to routing system */
/* Socket configuration controls. */
#define SIOCGIFNAME 0x8910 /* get iface name */
#define SIOCSIFLINK 0x8911 /* set iface channel */
#define SIOCGIFCONF 0x8912 /* get iface list */
#define SIOCGIFFLAGS 0x8913 /* get flags */
#define SIOCSIFFLAGS 0x8914 /* set flags */
#define SIOCGIFADDR 0x8915 /* get PA address */
#define SIOCSIFADDR 0x8916 /* set PA address */
#define SIOCGIFDSTADDR 0x8917 /* get remote PA address */
#define SIOCSIFDSTADDR 0x8918 /* set remote PA address */
#define SIOCGIFBRDADDR 0x8919 /* get broadcast PA address */
#define SIOCSIFBRDADDR 0x891a /* set broadcast PA address */
#define SIOCGIFNETMASK 0x891b /* get network PA mask */
#define SIOCSIFNETMASK 0x891c /* set network PA mask */
#define SIOCGIFMETRIC 0x891d /* get metric */
#define SIOCSIFMETRIC 0x891e /* set metric */
#define SIOCGIFMEM 0x891f /* get memory address (BSD) */
#define SIOCSIFMEM 0x8920 /* set memory address (BSD) */
#define SIOCGIFMTU 0x8921 /* get MTU size */
#define SIOCSIFMTU 0x8922 /* set MTU size */
#define SIOCSIFNAME 0x8923 /* set interface name */
#define SIOCSIFHWADDR 0x8924 /* set hardware address */
#define SIOCGIFENCAP 0x8925 /* get/set encapsulations */
#define SIOCSIFENCAP 0x8926
#define SIOCGIFHWADDR 0x8927 /* Get hardware address */
#define SIOCGIFSLAVE 0x8929 /* Driver slaving support */
#define SIOCSIFSLAVE 0x8930
#define SIOCADDMULTI 0x8931 /* Multicast address lists */
#define SIOCDELMULTI 0x8932
#define SIOCGIFINDEX 0x8933 /* name -> if_index mapping */
#define SIOGIFINDEX SIOCGIFINDEX /* misprint compatibility :-) */
#define SIOCSIFPFLAGS 0x8934 /* set/get extended flags set */
#define SIOCGIFPFLAGS 0x8935
#define SIOCDIFADDR 0x8936 /* delete PA address */
#define SIOCSIFHWBROADCAST 0x8937 /* set hardware broadcast addr */
#define SIOCGIFCOUNT 0x8938 /* get number of devices */
……
其中ioctl的参数需要借助结构体struct ifreq，
定义头文件：
/usr/include/linux/if.h
#if __UAPI_DEF_IF_IFREQ
struct ifreq {
#define IFHWADDRLEN 6
union
{
char ifrn_name[IFNAMSIZ]; /* if name, e.g. "en0" */
} ifr_ifrn;
union {
struct sockaddr ifru_addr;
struct sockaddr ifru_dstaddr;
struct sockaddr ifru_broadaddr;
struct sockaddr ifru_netmask;
struct sockaddr ifru_hwaddr;
short ifru_flags;
int ifru_ivalue;
int ifru_mtu;
struct ifmap ifru_map;
char ifru_slave[IFNAMSIZ]; /* Just fits the size */
char ifru_newname[IFNAMSIZ];
void * ifru_data;
struct if_settings ifru_settings;
} ifr_ifru;
};
#endif /* __UAPI_DEF_IF_IFREQ */
#define ifr_name ifr_ifrn.ifrn_name /* interface name */
#define ifr_hwaddr ifr_ifru.ifru_hwaddr /* MAC address */
#define ifr_addr ifr_ifru.ifru_addr /* address */
#define ifr_dstaddr ifr_ifru.ifru_dstaddr /* other end of p-p lnk */
#define ifr_broadaddr ifr_ifru.ifru_broadaddr /* broadcast address */
#define ifr_netmask ifr_ifru.ifru_netmask /* interface net mask */
#define ifr_flags ifr_ifru.ifru_flags /* flags */
#define ifr_metric ifr_ifru.ifru_ivalue /* metric */
#define ifr_mtu ifr_ifru.ifru_mtu /* mtu */
#define ifr_map ifr_ifru.ifru_map /* device map */
#define ifr_slave ifr_ifru.ifru_slave /* slave device */
#define ifr_data ifr_ifru.ifru_data /* for use by interface */
#define ifr_ifindex ifr_ifru.ifru_ivalue /* interface index */
#define ifr_bandwidth ifr_ifru.ifru_ivalue /* link bandwidth */
#define ifr_qlen ifr_ifru.ifru_ivalue /* Queue length */
#define ifr_newname ifr_ifru.ifru_newname /* New name */
#define ifr_settings ifr_ifru.ifru_settings /* Device/proto settings*/
二、函数实现
下面将实现不同功能的函数一一列举。
0. 列出所有可用网口
int list_all_port()
{
struct ifconf ifconf;
struct ifreq *ifr;
int m, n, s, fd;
if ((fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
return -11;
}
s = sizeof(struct ifreq)*5;
for (;;) {
ifr = malloc(s);
ifconf.ifc_len = s;
ifconf.ifc_req = ifr;
if (ioctl(fd, SIOCGIFCONF, &ifconf) < 0) {
perror("SIOCGIFCONF:");
free(ifr);
close(fd);
return 1;
}
if (ifconf.ifc_len != s)
break;
free(ifr);
s *= 2;
}
close(fd);
m = ifconf.ifc_len/sizeof(struct ifreq);
for (n = 0; n < m; n++)
{
printf("port:\t%s\n",ifconf.ifc_req[n].ifr_name);
}
free(ifr);
}
1. 获取指定网卡IP
int getLocalIp(const char *eth, char *ip) {
struct ifreq ifr;
struct sockaddr_in sin;
int fd;
bzero(&ifr, sizeof(ifr));
if ((fd = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
return -1;
}
strcpy(ifr.ifr_name, eth);
if (ioctl(fd, SIOCGIFADDR, &ifr) < 0) {
close(fd);
return -1;
}
memcpy(&sin, &ifr.ifr_addr, sizeof(sin));
snprintf(ip, IP_SIZE, "%s", inet_ntoa(sin.sin_addr));
close(fd);
return 0;
}
2. 设置本网卡IP地址
int setIpAddrManual(const char *eth, char *ipstr) {
int fd;
struct sockaddr_in sin;
struct ifreq ifr;
bzero(&ifr, sizeof(ifr));
if ((fd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
{
return -1;
}
strcpy(ifr.ifr_name, eth);
sin.sin_addr.s_addr = inet_addr(ipstr);
sin.sin_family = AF_INET;
memcpy(&ifr.ifr_addr, &sin, sizeof(sin));
if (ioctl(fd, SIOCSIFADDR, &ifr) < 0)
{
perror("");
close(fd);
return -1;
}
close(fd);
return 0;
}
3. 获取本机网卡Mac地址
int getLocalMac(const char *eth, char *mac) {
int fd;
struct ifreq ifr;
bzero(&ifr, sizeof(ifr));
if ((fd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
{
return -1;
}
strcpy(ifr.ifr_name, eth);
if (ioctl(fd, SIOCGIFHWADDR, &ifr) < 0)
{
close(fd);
return -1;
}
snprintf(mac,18, "%02x:%02x:%02x:%02x:%02x:%02x",
(unsigned char) ifr.ifr_hwaddr.sa_data[0],
(unsigned char) ifr.ifr_hwaddr.sa_data[1],
(unsigned char) ifr.ifr_hwaddr.sa_data[2],
(unsigned char) ifr.ifr_hwaddr.sa_data[3],
(unsigned char) ifr.ifr_hwaddr.sa_data[4],
(unsigned char) ifr.ifr_hwaddr.sa_data[5]);
close(fd);
return 0;
}
4. 设置网卡mac地址
/*
support format [00:11:22:33:44:55]
*/
#define MAC_ARRAY(mac_array) (unsigned int *)&mac_array[0],(unsigned int *)&mac_array[1],(unsigned int *)&mac_array[2],(unsigned int *)&mac_array[3],(unsigned int *)&mac_array[4],(unsigned int *)&mac_array[5]
int setLocalMac(const char *eth, char *mac) {
int fd;
struct ifreq ifr;
unsigned char mac_array[6] = {0};
bzero(&ifr, sizeof(ifr));
if ((fd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
{
return -1;
}
strcpy(ifr.ifr_name, eth);
ifr.ifr_hwaddr.sa_family = AF_LOCAL;
sscanf(mac,"%02x:%02x:%02x:%02x:%02x:%02x",
MAC_ARRAY(mac_array));
memcpy(ifr.ifr_hwaddr.sa_data,mac_array,6);
if (ioctl(fd, SIOCSIFHWADDR, &ifr) < 0)
{
perror("SIOCSIFHWADDR:");
close(fd);
return -1;
}
close(fd);
return 0;
}
注意：
- 网卡地址的第一字节必须是偶数
- sa_family 值必须为：AF_LOCAL
5. 获取网卡mtu
int getMtu(const char *eth, char *mtu) {
int fd;
struct ifreq ifr;
bzero(&ifr, sizeof(ifr));
if ((fd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
{
return -1;
}
strcpy(ifr.ifr_name, eth);
if (ioctl(fd, SIOCGIFMTU, &ifr) < 0)
{
close(fd);
return -1;
}
snprintf(mtu,64, "%d", (unsigned char) ifr.ifr_mtu);
close(fd);
return 0;
}
6. 获取广播地址
int getBroadAddr(const char *eth, char *ip) {
int fd;
struct sockaddr_in sin;
struct ifreq ifr;
bzero(&ifr, sizeof(ifr));
if ((fd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
{
return -1;
}
strcpy(ifr.ifr_name, eth);
if (ioctl(fd, SIOCGIFBRDADDR, &ifr) < 0)
{
perror("");
close(fd);
return -1;
}
memcpy(&sin, &ifr.ifr_broadaddr, sizeof(sin));
snprintf(ip, IP_SIZE, "%s", inet_ntoa(sin.sin_addr));
close(fd);
return 0;
}
7. 获取掩码
int getNetMask(const char *eth, char *mask) {
int fd;
struct sockaddr_in sin;
struct ifreq ifr;
bzero(&ifr, sizeof(ifr));
if ((fd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
{
return -1;
}
strcpy(ifr.ifr_name, eth);
if (ioctl(fd, SIOCGIFNETMASK, &ifr) < 0)
{
perror("");
close(fd);
return -1;
}
memcpy(&sin, &ifr.ifr_netmask, sizeof(sin));
snprintf(mask, IP_SIZE, "%s", inet_ntoa(sin.sin_addr));
close(fd);
return 0;
}
8. 获取网卡flag
int getFlags(const char *eth, char *fg) {
int fd;
struct sockaddr_in sin;
struct ifreq ifr;
bzero(&ifr, sizeof(ifr));
if ((fd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
{
return -1;
}
strcpy(ifr.ifr_name, eth);
if (ioctl(fd, SIOCGIFFLAGS, &ifr) < 0)
{
perror("");
close(fd);
return -1;
}
snprintf(fg, IP_SIZE, "%x", ifr.ifr_flags);
close(fd);
return 0;
}
三、测试
1. 测试程序
int main(int argc, char **argv)
{
int fg=0;
char mac[32]={};
char ip[IP_SIZE]={0};
char buf[64];
getBroadAddr(ethname,ip);
printf("broad ip:\t%s\n",ip);
getNetMask(ethname,ip);
printf("mask:\t%s\n",ip);
setIpAddrManual(ethname, "1.1.1.1");
getLocalIp(ethname,ip);
printf("ip:\t%s\n",ip);
setLocalMac(ethname,"00:11:22:33:44:55");
getLocalMac(ethname,mac);
printf("mac:\t%s\n",mac);
getMtu(ethname,buf);
printf("mtu:\t%s\n",buf);
return 1;
}
2. 执行结果
执行后结果：
peng@ubuntu:~/work/test/ip$ ifconfig
eth0 Link encap:Ethernet HWaddr 00:11:22:33:44:55
inet addr:1.1.1.1 Bcast:1.255.255.255 Mask:255.0.0.0
inet6 addr: fe80::d9d4:d42b:a04a:9d40/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:188577 errors:0 dropped:0 overruns:0 frame:0
TX packets:208116 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:53762370 (53.7 MB) TX bytes:172094089 (172.0 MB)
完整代码获取，请点赞转发，并后台留言：eth