目录
ioctl
原型如下:
#include <sys/ioctl.h>
int ioctl(int fd,int request,...);
参数:
fd : 文件描述符
request: 表示要请求的信息。如IP地址、网络掩码等
... : 后面的可变参数根据request而定
比如我们请求所有网络接口的清单:
struct ifconf IoCtlReq;
...
ioctl( Sock,SIocgIFCONF,&IoCtlReq )
与接口相关的request如下表所示
SIocgIFCONF SIOCSIFADDR SIocgIFADDR SIOCSIFFLAGS SIocgIFFLAGS SIOCSIFDSTADDR SIocgIFDSTADDR SIocgIFBRDADDR SIOCSIFBRDADDR SIocgIFNETMASK SIOCSIFNETMASK SIocgIFMETRIC SIOCSIFMETRIC SIocgIFMTU SIOCxxx |
获取所有接口的清单 设置接口地址 获取接口地址 设置接口标志 获取接口标志 设置点到点地址 获取点到点地址 获取广播地址 设置广播地址 获取子网掩码 设置子网掩码 获取接口的测度 设置接口的测度 获取接口MTU (还有很多取决于系统的实现) |
struct ifconf struct ifreq struct ifreq struct ifreq struct ifreq struct ifreq struct ifreq struct ifreq struct ifreq struct ifreq struct ifreq struct ifreq struct ifreq struct ifreq
|
struct ifreq
结构体 struct ifreq用来保存某个接口的信息。
// if.h
/*
* Interface request structure used for socket
* ioctl's. All interface ioctl's must have parameter
* deFinitions which begin with ifr_name. The
* remainder may be interface specific.
*/
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 __user * ifru_data;
struct if_settings ifru_settings;
} ifr_ifru;
};
#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*/
ifr_name 标识了某一接口。
可以通过ioctl获取该接口的信息。如:
ioctl(Sock,SIocgIFNETMASK,&IfReq);//获取网络接口地址掩码
该代码需要先对IfReq->ifr_name赋值,然后获取与IfReq->ifr_name向匹配的网络接口 的地址掩码
struct ifconf
结构体struct ifconf通常用来保存所有接口信息
// if.h
/*
* Structure used in SIocgIFCONF request.
* Used to retrieve interface configuration
* for machine (useful for programs which
* must kNow all networks accessible).
*/
struct ifconf {
int ifc_len; /* size of buffer */
union {
char __user *ifcu_buf;
struct ifreq __user *ifcu_req;
} ifc_ifcu;
};
#define ifc_buf ifc_ifcu.ifcu_buf /* buffer address */
#define ifc_req ifc_ifcu.ifcu_req /* array of structures */
该结构体可以用来获取所哟网络接口的名字和信息(不是全部信息,是ip地址)
实例:
#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <net/if.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <netdb.h>
#include <string.h>
#include <fcntl.h>
#include <string.h>
#include <errno.h>
typedef uint32_t uint32;
#define MAX_IF 10
int main()
{
struct ifreq ifVec[MAX_IF];//用来保存所有接口
int sock = -1;
if ((sock = socket( AF_INET,SOCK_DGRAM,0 )) < 0)
{
fprintf(stderr,"Error:%d,cannot open RAM;\n");
}
// get if vector
struct ifconf ioIfConf;
ioIfConf.ifc_buf = (void *)ifVec;
ioIfConf.ifc_len = sizeof(ifVec);
printf("Len:%d\n",ioIfConf.ifc_len);
if (ioctl(sock,&ioIfConf) < 0) //获取所有网络接口信息
{
fprintf(stderr,"Error:%d ioctl IFCONF\n");
}
printf("Len:%d\n",ioIfConf.ifc_len); // 和前面到len对比,发现ioctl修改里len到大小
//循环打印每个网络接口到信息
{
struct ifreq *ifPt;
struct ifreq *ifEndPt;
ifPt = ifVec;
ifEndPt = (void *)((char *)ifVec + ioIfConf.ifc_len);
for (ifPt = ifVec; ifPt < ifEndPt; ifPt++)
{
struct ifreq ifReq;
if (ifPt->ifr_addr.sa_family != AF_INET)
{
continue;
}
// Temp keepers of interface params...
uint32 u32_addr,u32_mask;
/* 打印ip地址 */
char ipDotBuf[16],subnetDotBuf[16],maskDotBuf[16]; // 保存点分十进制到ip地址
u32_addr = ((struct sockaddr_in *)&ifPt->ifr_addr)->sin_addr.s_addr;
inet_ntop(AF_INET,&u32_addr,ipDotBuf,(socklen_t )sizeof(ipDotBuf));
printf("IP Address: %s\n",ipDotBuf);
/* 打印地址掩码 */
bzero(&ifReq,sizeof(struct ifreq));
memcpy(ifReq.ifr_name,ifPt->ifr_name,sizeof(ifReq.ifr_name));
if (ioctl(sock,&ifReq ) < 0)
{
fprintf(stderr,"Error: %d,cannot get mask\n",errno);
}
else
{
u32_mask = ((struct sockaddr_in *)&ifReq.ifr_addr)->sin_addr.s_addr;
inet_ntop(AF_INET,&u32_mask,maskDotBuf,(socklen_t )sizeof(maskDotBuf));
printf("Mask: %s\n",maskDotBuf);
}
/* 打印MTU */
bzero(&ifReq,SIocgIFMTU,cannot get MTU\n",errno);
}
else
{
printf("SIocgIFMTU:%d\n",ifReq.ifr_mtu);
}
/* 其他信息的打印方式与掩码和MTU相同 */
}
}
}
运行结果:
windeal@ubuntu:~/Windeal/apue$ ./exe
Len:320
Len:64
IP Address: 127.0.0.1
Mask: 255.0.0.0
SIocgIFMTU:16436
IP Address: 172.17.92.198
Mask: 255.255.254.0
SIocgIFMTU:1500
windeal@ubuntu:~/Windeal/apue$
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