函数 : ioctl(int fd, int request, void * arg)
定义 :
功能 : 控制I/O设备, 提供了一种获得设备信息和向设备发送控制参数的手段.
参数 : int fd 文件句柄. 用于socket时, 是socket套接字.
int request 函数定义的所有操作. 关于socket的操作, 定义在文件中.
void *arg 指针的类型依赖于request参数.
| 类别 |
Request |
说明 |
数据类型 |
| 套 |
SIOCATMARK |
是否位于带外标记 |
int |
| 文 |
FIONBIN |
设置/ 清除非阻塞I/O 标志 |
int |
| 接 |
SIOCGIFCONF |
获取所有接口的清单 |
struct ifconf |
| ARP |
SIOCSARP |
创建/ 修改ARP 表项 |
struct arpreq |
| 路 |
SIOCADDRT |
增加路径 |
struct rtentry |
| 流 |
I_xxx |
|
|
socket最常用到的结构体: struct ifreq 定义在.(包括struct ifconf/ifr_flags等的定义)
一、获取
以下例程通过ioctl获取设备"eth0"的IP/掩码/硬件址
- #include "stdio.h"
- #include "stdlib.h"
- #include "string.h"
- #include "net/if.h"
- #include "arpa/inet.h"
- #include "linux/sockios.h"
- int main(int argc,char *argv[])
- {
- struct sockaddr_in *addr;
- struct ifreq ifr;
- char*address;
- int sockfd;
- char *name = "eth0";
- if( strlen(name) >= IFNAMSIZ)
- printf("device name is error.\n"), exit(0);
-
- strcpy( ifr.ifr_name, name);
-
- sockfd = socket(AF_INET,SOCK_DGRAM,0);
- //get inet addr
- if( ioctl( sockfd, SIOCGIFADDR, &ifr) == -1)
- printf("ioctl error.\n"), exit(0);
- addr = (struct sockaddr_in *)&(ifr.ifr_addr);
- address = inet_ntoa(addr->sin_addr);
- printf("inet addr: %s\n",address);
- //get Mask
- if( ioctl( sockfd, SIOCGIFNETMASK, &ifr) == -1)
- printf("ioctl error.\n"), exit(0);
- addr = (struct sockaddr_in *)&ifr.ifr_addr;
- address = inet_ntoa(addr->sin_addr);
- printf("Mask: %s\n",address);
- //get HWaddr
- u_int8_t hd[6];
- if(ioctl(sockfd, SIOCGIFHWADDR, &ifr) == -1)
- printf("hwaddr error.\n"), exit(0);
- memcpy( hd, ifr.ifr_hwaddr.sa_data, sizeof(hd));
- printf("HWaddr: %02X:%02X:%02X:%02X:%02X:%02X\n", hd[0], hd[1], hd[2], hd[3], hd[4], hd[5]);
-
- exit(0);
- }
二、设置
以下例程设置eth0的IP地址.
- #include "stdio.h"
- #include "stdlib.h"
- #include "string.h"
- #include "net/if.h"
- #include "arpa/inet.h"
- #include "linux/sockios.h"
- int main(int argc,char *argv[])
- {
- char *dev = "eth0";
- char *ip = "192.168.1.252";
-
- struct ifreq ifr;
- if( strlen(dev) >= IFNAMSIZ)
- printf("device name error.\n"), exit(0);
- else
- strcpy( ifr.ifr_name, dev);
-
- int sockfd = socket(AF_INET,SOCK_DGRAM,0);
- //get inet addr
- if( ioctl( sockfd, SIOCGIFADDR, &ifr) == -1)
- printf("ioctl error.\n"), exit(0);
-
- struct sockaddr_in *addr = (struct sockaddr_in *)&(ifr.ifr_addr);
- char * address = inet_ntoa(addr->sin_addr);
- printf("current inet addr: %s\n",address);
- //set inet addr
- struct sockaddr_in *p = (struct sockaddr_in *)&(ifr.ifr_addr);
- p->sin_family = AF_INET;
- inet_aton( ip, &(p->sin_addr));
- if( ioctl( sockfd, SIOCSIFADDR, &ifr) == -1)
- printf("ioctl error.\n"), exit(0);
- else
- printf("change inet addr to: %s\n", ip);
- //any OS need active dev.
- /*ifr.ifr_flags |= IFF_UP;
- if( ioctl( sockfd, SIOCSIFFLAGS, &ifr) == -1)
- printf("active fault.\n"), exit(0);
- else
- printf("%s[%s] is working...\n", dev, ip);
- */
-
- close(sockfd);
- exit(1);
- //end
- }
屏蔽的代码用于设置IP后, 激活新设置. 多数系统不需要这步操作.
而且这步仅作演示. 真实使用的时候, 至少应该
1. 获取当前ifr.ifr_flags
2. ifr.ifr_flags |= IFF_UP;
以上是ioctl的一些示例, 实战中灵活使用、举一反三.
