Mac usr/include/linux,用ioctl获取无线网络信息 /usr//include/linux/wireless.h

Mac usr/include/linux,用ioctl获取无线网络信息 /usr//include/linux/wireless.h

1、UNIX Network Programming环境搭建

Unix NetWork Programming――环境搭建(解决unp.h等源码编译问题)

注：按照连接操作即可，编译要加 -lunp  选项

2、用户态和核心态的交换方式

在

linux下，要实现核心态和用户态数据的交互，有多种方式：可以通用socket创建特殊套接字，利用套接字实现数据交互；通过proc文件系统创建文

件来进行数据交互；还可以使用设备文件的方式，访问设备文件会调用设备驱动相应的例程，设备驱动本身就是核心态和用户态的一个接口，Tun/tap驱动就

是利用设备文件实现用户态和核心态的数据交互。

3、与系统错误有关的函数

(1)errno

头文件：#include

函数原型：errno

功能：记录系统的最后一次错误代码

参数：无

返回值：错误代号(整型值)

例子：

if((sockfd = socket(AF_INET, SOCK_DGRAM, 0)) == -1) {

fprintf(stderr, "Cannot open socket /n");

fprintf(stderr, "errno = %d /n", errno);      fprintf(stderr, "Error description is : %s/n",strerror(errno));        exit(1);

}

printf("Socket opened successfully /n");

(2)strerror   strerror_r

头文件：#include

函数原型：

char *strerror(int errnum);

char *_strerror(const char *strErrMsg);

wchar_t * _wcserror(int errnum);

wchar_t * __wcserror(const wchar_t *strErrMsg);

参数：errnum――错误代码，strErrMsg――用户提供的信息。

返回值：指向错误信息的指针。

例子：同(1)

(3)perror

头文件：#include#include//

函数原型：void perror(const char *s); perror ("open_port");

函数功能：

perror ( )用 来 将 上 一 个 函 数 发 生 错 误 的 原 因 输 出 到 标 准 设备 (stderr) 。参数 s 所指的字符串会先打印出,后面再加上错误原因字符串。此错误原因依照全局变量errno 的值来决定要输出的字符串。

在库函数中有个errno变量，每个errno值对应着以字符串表示的错误类型。当你调用"某些"函数出错时，该函数已经重新设置了errno的值。perror函数只是将你输入的一些信息和现在的errno所对应的错误一起输出。

参数：用户输入的字符串

返回值：无

例子：

if(( sockfd = socket(AF_INET,SOCK_DGRAM,0))<0)

{

perror("error");

exit(1);

}

else

{

printf("socket created successfully!/n");

printf("socket id:%d/n",sockfd);

printf("remote ip:%s/n",REMOTEIP);

printf("remote port: %d/n/n",REMOTEPORT);

}

总结：貌似perror比较方便

4、memset

头文件：在C中 or 在C++中

函数原型：void *memset(void *s, int ch, size_t n);

函数功能：将s中前n个字节替换为ch并返回s；作用是在一段内存块中填充某个给定的值，它是对较大的结构体或数组进行清零操作的一种最快方法。

注：如果不用memeset清零，可能会出现野值。

5、iwreq结构体

(1)头文件：#include

struct

iwreq {union{charifrn_name[IFNAMSIZ];/* if name, e.g. "eth0" */}

ifr_ifrn;/* Data part */union{/* Config - generic */char

name[IFNAMSIZ];/* Name : used to verify the presence of wireless

extensions. * Name of the */struct iw_point

essid;/* Extended network name */struct iw_paramnwid;/* network id

(or domain - the cell) */struct iw_freqfreq;/* frequency or channel :

* 0-1000 = channel * > 1000 = frequency in Hz */

struct iw_paramsens;/* signal level threshold */struct iw_param

bitrate;/* default bit rate */struct iw_paramrts;/* RTS threshold

threshold */struct iw_paramfrag;/* Fragmentation threshold */

__u32mode;/* Operation mode */struct iw_pointencoding;/*

Encoding stuff : tokens */struct iw_parampower;/* PM

duration/timeout */struct sockaddrap_addr;/* Access point address */

struct iw_pointdata;/* Other large parameters */}u;};(2)struct

iw_point{ caddr_tpointer;/* Pointer to the data (in user space) */

__u16length;/* number of fields or size in bytes */ __u16flags;

/* Optional params */};structiw_param{ __s32value;/* The value of

the parameter itself */ __u8fixed;/* Hardware should not use auto

select */ __u8disabled;/* Disable the feature */ __u16flags;/*

Various specifc flags (if any) */};其中typedef   void*   caddr_t

即caddr_t是void*型typedef unsigned short __u16 即__u16是unsigned short型(以_t结尾的一般说明是typedef定义后的数据类型，typedef主要解决跨平台编译问题)

6、ifreq

/* 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

# define IFNAMSIZ IF_NAMESIZE

union

{

char ifrn_name[IFNAMSIZ]; /* Interface 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 int ifru_flags;

int ifru_ivalue;

int ifru_mtu;

struct ifmap ifru_map;

char ifru_slave[IFNAMSIZ]; /* Just fits the size */

char ifru_newname[IFNAMSIZ];

__caddr_t ifru_data;

} 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 _IOT_ifreq _IOT(_IOTS(char),IFNAMSIZ,_IOTS(char),16,0,0)

# define _IOT_ifreq_short _IOT(_IOTS(char),IFNAMSIZ,_IOTS(short),1,0,0)

# define _IOT_ifreq_int _IOT(_IOTS(char),IFNAMSIZ,_IOTS(int),1,0,0)

注：其中sockaddr

struct sockaddr {

uint8_t sa_len;

sa_family_t sa_family;    /*地址族：AF_XXX*/

char sa_data[14];          /*14字节协议地址*/

}

7、struct union

参考：.html

(1)

struct

和union都是由多个不同的数据类型成员组成, 但在任何同一时刻, union中只存放了一个被选中的成员,

而struct的所有成员都存在。在struct中，各成员都占有自己的内存空间，它们是同时存在的。一个struct变量的总长度等于所有成员长度之

和。在Union中，所有成员不能同时占用它的内存空间，它们不能同时存在。Union变量的长度等于最长的成员的长度。

(2)对于union的不同成员赋值, 将会对其它成员重写, 原来成员的值就不存在了,而对于struct的不同成员赋值是互不影响的。注：(１)、(２)两点是相通的，即union的成员共用一块内存(该块内存的大小是union成员中占用内存长度最长的)，而struct各成员占用自己的内存空间。(3)例子

#include

void main()

{

union{                                                /*定义一个联合*/

int i;

struct{                                     /*在联合中定义一个结构*/

char first;

char second;

}half;

}number;

number.i=0x4241; /*联合成员赋值*/

cout

number.half.first='a';                  /*联合中结构成员赋值*/

number.half.second='b';

cout<

/*每一个变量前都加一个 << hex    ,并且int型可以转换，而float、double是转化不了的*/

}

输出结果为:

AB

6261

在这里i 和 half结构是共用内存

number.i=0x4241给i赋值后,内存中以二进制存储0100 0010 0100 0001

按顺序对应到结构中

halt.first=01000010   转换成10进制就是66(字母A的asc码)

halt.second=01000001 转换成10进制是65   (字母B的asc码)

所以输出后就是 AB

8、wireless.h       ioctl中有关无线网络的request请求参数

/*

* This file define a set of standard wireless extensions * * Version :9

16.10.99 * * Authors :Jean Tourrilhes - HPL -

*/#ifndef _LINUX_WIRELESS_H#define

_LINUX_WIRELESS_H/************************** DOCUMENTATION

**************************//* * Basically, the wireless extensions are

for now a set of standard ioctl * call + /proc/net/wireless * * The

entry /proc/net/wireless give statistics and information on the *

driver. * This is better than having each driver having its entry

because * its centralised and we may remove the driver module safely. * *

Ioctl are used to configure the driver and issue commands. This is *

better than command line options of insmod because we may want to *

change dynamically (while the driver is running) some parameters. * *

The ioctl mechanimsm are copied from standard devices ioctl. * We have

the list of command plus a structure descibing the * *

Note that to add these ioctl, I was obliged to modify : *

net/core/dev.c (two place + add include) *net/ipv4/af_inet.c (one place

+ add include) * * /proc/net/wireless is a copy of /proc/net/dev. * We

have a structure for data passed from the driver to /proc/net/wireless *

Too add this, I've modified : *net/core/dev.c (two other places) *

include/linux/netdevice.h (one place) *include/linux/proc_fs.h (one

place) * * Do not add here things that are redundant with other

mechanisms * (drivers init, ifconfig, /proc/net/dev, ...) and with are

not * wireless specific. * * These wireless extensions are not magic :

each driver has to provide * support * * IMPORTANT NOTE : As

everything in the kernel, this is very much a * work in progress.

Contact me if you have ideas

*//***************************** INCLUDES

*****************************/#include /* for

"caddr_t" et al*/#include /* for "struct

sockaddr" et al*/#include /* for IFNAMSIZ and

< *//**************************** CONSTANTS

****************************//* --------------------------- VERSION

--------------------------- *//* * This constant is used to know the

availability of the wireless * extensions and to know which version of

wireless extensions it is * (there is some stuff that will be added in

) * I just plan to increment with each new version.

*/#define WIRELESS_EXT9/* * Changes : * * V2 to V3 * -------- *Alan

Cox start some incompatibles changes. I've integrated a bit more. *-

Encryption renamed to Encode to avoid US regulation problems *-

Frequency changed from float to struct to avoid problems on old 386 * *

V3 to V4 * -------- *- Add sensitivity * * V4 to V5 * -------- *-

Missing encoding definitions in range *- Access points stuff * * V5 to

V6 * -------- *- 802.11 support (ESSID ioctls) * * V6 to V7 * -------- *

- define IW_ESSID_MAX_SIZE and IW_MAX_AP * * V7 to V8 * -------- *-

Changed my e-mail address *- More 802.11 support (nickname, rate, rts,

frag) *- List index in frequencies * * V8 to V9 * -------- *- Support

for 'mode of operation' (ad-hoc, ) *- Support for unicast and

multicast power saving *- Change encoding to support larger tokens

(>64 bits) *- Updated iw_params (disable, flags) and use it for

NWID *- Extracted iw_point from iwreq for clarity *//*

-------------------------- IOCTL LIST -------------------------- *//*

Basic operations */#define SIOCSIWNAME0x8B00/* Unused ??? */#define

SIOCGIWNAME0x8B01/* get name */#define SIOCSIWNWID0x8B02/* set

network id (the cell) */#define SIOCGIWNWID0x8B03/* get network id

*/#define SIOCSIWFREQ0x8B04/* set channel/frequency */#define

SIOCGIWFREQ0x8B05/* get channel/frequency */#define SIOCSIWMODE

0x8B06/* set operation mode */#define SIOCGIWMODE0x8B07/* get

operation mode */#define SIOCSIWSENS0x8B08/* set sensitivity

*/#define SIOCGIWSENS0x8B09/* get sensitivity *//* Informative stuff

*/#define SIOCSIWRANGE0x8B0A/* Unused ??? */#define SIOCGIWRANGE

0x8B0B/* Get range of parameters */#define SIOCSIWPRIV0x8B0C/*

Unused ??? */#define SIOCGIWPRIV0x8B0D/* get private ioctl interface

info *//* Mobile IP support */#define SIOCSIWSPY0x8B10/* set spy

addresses */#define SIOCGIWSPY0x8B11/* get spy info (quality of link)

*//* Access Point manipulation */#define SIOCSIWAP0x8B14/* set

access point MAC addresses */#define SIOCGIWAP0x8B15/* get access

point MAC addresses */#define SIOCGIWAPLIST0x8B17/* get list of

access point in range *//* 802.11 specific support */#define

SIOCSIWESSID0x8B1A/* set ESSID (network name) */#define SIOCGIWESSID

0x8B1B/* get ESSID */#define SIOCSIWNICKN0x8B1C/* set node

name/nickname */#define SIOCGIWNICKN0x8B1D/* get node name/nickname

*//* As the ESSID and NICKN are strings up to 32 bytes long, it doesn't

fit * within the 'iwreq' structure, so we need to use the 'data' member

to * point to a string in user space, like it is done * The

"flags" member indicate if the ESSID is active or not (promiscuous).

*//* Other parameters usefull in 802.11 and some other devices */#define

SIOCSIWRATE0x8B20/* set default bit rate (bps) */#define SIOCGIWRATE

0x8B21/* get default bit rate (bps) */#define SIOCSIWRTS0x8B22/*

set RTS/CTS threshold (bytes) */#define SIOCGIWRTS0x8B23/* get

RTS/CTS threshold (bytes) */#define SIOCSIWFRAG0x8B24/* set

fragmentation thr (bytes) */#define SIOCGIWFRAG0x8B25/* get

fragmentation thr (bytes) *//* Encoding stuff (scrambling, hardware

security, ) */#define SIOCSIWENCODE0x8B2A/* set encoding token

& mode */#define SIOCGIWENCODE0x8B2B/* get encoding token &

mode *//* Power saving stuff (power management, unicast and multicast)

*/#define SIOCSIWPOWER0x8B2C/* set Power Management settings

*/#define SIOCGIWPOWER0x8B2D/* get Power Management settings *//* Get

statistics */#define SIOCGIWSTAT0x8B2E/* get an struct iw_statistics

*//* ------------------------- IOCTL STUFF -------------------------

*//* The first and the last (range) */#define SIOCIWFIRST0x8B00#define

SIOCIWLAST0x8B30/* Even : get (world access), odd : set (root access)

*/#define IW_IS_SET(cmd)(!((cmd) & 0x1))#define IW_IS_GET(cmd)

((cmd) & 0x1)/* ------------------------- PRIVATE INFO

------------------------- *//* * The following is used with SIOCGIWPRIV.

It allow a driver to define * the interface (name, type of data) for

its private ioctl. * Privates ioctl are SIOCDEVPRIVATE ->

SIOCDEVPRIVATE + 0xF */#define IW_PRIV_TYPE_MASK0x7000/* Type of

arguments */#define IW_PRIV_TYPE_NONE0x0000#define IW_PRIV_TYPE_BYTE

0x1000/* Char as number */#define IW_PRIV_TYPE_CHAR0x2000/* Char as

character */#define IW_PRIV_TYPE_INT0x4000/* 32 bits int */#define

IW_PRIV_TYPE_FLOAT0x5000#define IW_PRIV_SIZE_FIXED0x0800/* Variable

or fixed nuber of args */#define IW_PRIV_SIZE_MASK0x07FF/* Max number

of those args *//* * Note : if the number of args is fixed and the size

< 16 octets, * instead of passing a pointer we will put args in the

*//* ----------------------- OTHER CONSTANTS

----------------------- *//* Maximum frequencies in the range struct

*/#define IW_MAX_FREQUENCIES16/* Note : if you have something like 80

frequencies, * don't increase this constant and don't fill the frequency

list. * The user will be able to set by *//* Maximum

bit rates in the range struct */#define IW_MAX_BITRATES8/* Maximum of

address that you may set with SPY */#define IW_MAX_SPY8/* Maximum of

address that you may get in the list of access points in range

*/#define IW_MAX_AP8/* Maximum size of the ESSID and NICKN strings

*/#define IW_ESSID_MAX_SIZE32/* Modes of operation */#define

IW_MODE_AUTO0/* Let the driver decides */#define IW_MODE_ADHOC1/*

Single cell network */#define IW_MODE_INFRA2/* Multi cell network,

roaming, ... */#define IW_MODE_MASTER3/* Synchronisation master or

Access Point */#define IW_MODE_REPEAT4/* Wireless Repeater (forwarder)

*/#define IW_MODE_SECOND5/* Secondary master/repeater (backup) *//*

Maximum number of size of encoding token available * they are listed in

the range structure */#define IW_MAX_ENCODING_SIZES8/* Maximum size of

the encoding token in bytes */#define IW_ENCODING_TOKEN_MAX32/* 256

bits (for now) *//* Flags for encoding (along with the token) */#define

IW_ENCODE_INDEX0x00FF/* Token index (if needed) */#define

IW_ENCODE_FLAGS0xF000/* Flags defined below */#define

IW_ENCODE_DISABLED0x8000/* Encoding disabled */#define

IW_ENCODE_ENABLED0x0000/* Encoding enabled */#define

IW_ENCODE_RESTRICTED0x4000/* Refuse non-encoded packets */#define

IW_ENCODE_OPEN0x2000/* Accept non-encoded packets *//* Power

management flags available (along with the value, if any) */#define

IW_POWER_ON0x0000/* */#define IW_POWER_TYPE0xF000/*

Type of parameter */#define IW_POWER_PERIOD0x1000/* Value is a

period/duration of */#define IW_POWER_TIMEOUT0x2000/* Value is a

timeout (to go asleep) */#define IW_POWER_MODE0x0F00/* Power

Management mode */#define IW_POWER_UNICAST_R0x0100/* Receive only

unicast messages */#define IW_POWER_MULTICAST_R0x0200/* Receive only

multicast messages */#define IW_POWER_ALL_R0x0300/* Receive all

messages though PM */#define IW_POWER_FORCE_S0x0400/* Force PM

procedure for sending unicast */#define IW_POWER_REPEATER0x0800/*

Repeat broadcast messages in PM period *//******************************

TYPES ******************************//* ---------------------------

SUBTYPES --------------------------- *//* *Generic format for most

parameters that fit in an int */structiw_param{ __s32value;/* The

value of the parameter itself */ __u8fixed;/* Hardware should not

use auto select */ __u8disabled;/* Disable the feature */ __u16

flags;/* Various specifc flags (if any) */};/* *For all data larger

than 16 octets, we need to use a *pointer to memory alocated in user

space. */structiw_point{ caddr_tpointer;/* Pointer to the data (in

user space) */ __u16length;/* number of fields or size in bytes */

__u16flags;/* Optional params */};/* *A frequency *For numbers

lower than 10^9, we encode the number in 'm' and *set 'e' to 0 *For

number greater than 10^9, we pide it by the lowest power *of 10 to get

'm' lower than 10^9, with 'm'= f / (10^'e')... *The power of 10 is in

'e', the result of the pision is in 'm'. */structiw_freq{__u32m;/*

Mantissa */__u16e;/* Exponent */__u8i;/* List index (when in

range struct) */};/* *Quality of the link */structiw_quality{__u8

qual;/* link quality (%retries, SNR ) */__u8level;/*

signal level */__u8noise;/* noise level */__u8updated;/* Flags

to know if updated */};/* *Packet discarded in the wireless adapter due

to *"wireless" */structiw_discarded{__u32

nwid;/* Wrong nwid */__u32code;/* Unable to code/decode */__u32

misc;/* Others cases */};/* ------------------------ WIRELESS STATS

------------------------ *//* * Wireless statistics (used for

/proc/net/wireless) */structiw_statistics{__u16status;/* Status

* - device dependent for now */struct iw_qualityqual;/* Quality

of the link * (instant/mean/max) */struct iw_discardeddiscard;

/* Packet discarded counts */};/* ------------------------ IOCTL REQUEST

------------------------ *//* * The structure to exchange data for

ioctl. * This structure is the same as 'struct ifreq', but (re)defined

for * * * Note that it should fit on the same memory

footprint ! * You should check this when increasing the above structures

(16 octets) * 16 octets = 128 bits. Warning, pointers might be 64 bits

< */structiwreq {union{charifrn_name[IFNAMSIZ];/* if name,

< "eth0" */} ifr_ifrn;/* Data part */union{/* Config - generic

*/charname[IFNAMSIZ];/* Name : used to verify the presence of

wireless extensions. * Name of the */struct

iw_pointessid;/* Extended network name */struct iw_paramnwid;/*

network id (or domain - the cell) */struct iw_freqfreq;/* frequency

or channel : * 0-1000 = channel * > 1000 = frequency in Hz

*/struct iw_paramsens;/* signal level threshold */struct iw_param

bitrate;/* default bit rate */struct iw_paramrts;/* RTS threshold

threshold */struct iw_paramfrag;/* Fragmentation threshold */

__u32mode;/* Operation mode */struct iw_pointencoding;/*

Encoding stuff : tokens */struct iw_parampower;/* PM

duration/timeout */struct sockaddrap_addr;/* Access point address */

struct iw_pointdata;/* Other large parameters */}u;};/*

-------------------------- IOCTL DATA -------------------------- *//* *

For those ioctl which want to exchange mode data that what could *fit

in the *//* *Range of parameters */structiw_range{

/* Informative stuff (to choose between different interface) */__u32

throughput;/* To give *//* In theory this value should be

the maximum benchmarked * TCP/IP throughput, because with most of these

devices the * bit rate is meaningless (overhead an co) to estimate how

* fast the connection will go and pick the fastest one. * I suggest

people to play with Netperf or *//* NWID (or domain

id) */__u32min_nwid;/* Minimal NWID we are able to set */__u32

max_nwid;/* Maximal NWID we are able to set *//* Frequency */__u16

num_channels;/* Number of channels [0; num - 1] */__u8num_frequency;

/* Number of entry in the list */struct iw_freq

freq[IW_MAX_FREQUENCIES];/* list *//* Note : this frequency list

doesn't need to fit channel numbers *//* signal level threshold range

*/__s32sensitivity;/* Quality of link & SNR stuff */struct

iw_qualitymax_qual;/* Quality of the link *//* Rates */__u8

num_bitrates;/* Number of entries in the list */__s32

bitrate[IW_MAX_BITRATES];/* list, in bps *//* RTS threshold */__s32

min_rts;/* Minimal RTS threshold */__s32max_rts;/* Maximal RTS

threshold *//* Frag threshold */__s32min_frag;/* Minimal frag

threshold */__s32max_frag;/* Maximal frag threshold *//* Power

Management duration & timeout */__s32min_pmd;/* Minimal PM

duration */__s32max_pmd;/* Maximal PM duration */__s32min_pmt;/*

Minimal PM timeout */__s32max_pmt;/* Maximal PM timeout *//*

Encoder stuff */__u16encoding_size[IW_MAX_ENCODING_SIZES];/*

Different token sizes */__u8num_encoding_sizes;/* Number of entry in

the list */__u8max_encoding_tokens;/* Max number of tokens */};/* *

Private ioctl interface information */ structiw_priv_args{__u32cmd;

/* Number of the ioctl to issue */__u16set_args;/* Type and number

of args */__u16get_args;/* Type and number of args */char

name[IFNAMSIZ];/* Name of the extension */};#endif/* _LINUX_WIRELESS_H

*/

9、ioctl获取ESSID 和AP的MAC

/***************code description***************

get current connecting ESSID and its AP's MAC.

by fys 2012/8/9

****************code description***************/

#include #include #include #include #include #include #include #include #include #include #include using namespace std;

#define IW_INTERFACE "wlan0"

extern int errno;

struct iwreq wreq;

int main (void)

{

int i;

int sockfd;

memset(&wreq, 0, sizeof(struct iwreq));

sprintf(wreq.ifr_name, IW_INTERFACE);//?

/*create a socket to get info from ioctl*/

if((sockfd = socket(AF_INET, SOCK_DGRAM, 0)) == -1) {

//fprintf(stderr, "Cannot open socket /n");

//fprintf(stderr, "errno = %d /n", errno);

//fprintf(stderr, "Error description is : %s/n",strerror(errno));

perror("Cannot creat socket,error");

exit(1);

}

else {

printf("Socket opened successfully /n");

}

/*create a socket to get info from ioctl*/

char buffer[32];

memset(buffer, 0, 32);

wreq.u.essid.pointer = buffer;//if not write these codes , the program maybe wrong.

wreq.u.essid.length = 32;

/*get ESSID from ioctl*/

if (ioctl(sockfd,SIOCGIWESSID, &wreq) == -1) {

perror("IOCTL SIOCGIWESSID Failed,error");

exit(2);

}

else {

printf("IOCTL SIOCGIWESSID Successfull/n");

}

/*get ESSID from ioctl*/

/*output current connecting essid*/

printf("%s/n",wreq.u.essid.pointer);

/*output current connecting essid*/

/*get AP info from ioctl*/

if (ioctl(sockfd,SIOCGIWAP, &wreq) == -1) {

perror("IOCTL SIOCGIWAP Failed,error");

exit(2);

}

else {

printf("IOCTL SIOCGIWAP Successfull/n");

}

/*get AP info from ioctl*/

/* output current connecting AP MAC*/

for (i = 0; i < 6; i++) {

unsigned char *APaddr = (unsigned char *) wreq.u.ap_addr.sa_data;

printf("%02x", (int) APaddr[i]);//mac[i] means 1 byte ,i.e. 8 bits.

if (i != 5)

printf("%c", ':');

else

printf("/n");

}

/* output current connecting AP MAC*/

}