---
# System prepended metadata

title: wireless.h

---

wireless.h
===

我們可以透過netdevice取得網路介面卡的資訊，然而卻無法獲取無線網路卡的連接資訊。幸好Linux Kernel有提供standard wireless extensions解決這個問題。[wireless.h](https://elixir.bootlin.com/linux/latest/source/include/uapi/linux/wireless.h)

使用方法如同netdevice，也是開啟一個新的socket，並透過ioctl發送request取得結果。

:::info
socket:
```Clike=
#include <sys/socket.h>
int socket(int domain, int type, int protocol);
```

ioctl:
```Clike=
#include <sys/ioctl.h>
int ioctl(int d, int request, ...);
```
:::

wireless支援的request如下:
```Clike=
/**************************** CONSTANTS ****************************/

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

/* Wireless Identification */
#define SIOCSIWCOMMIT	0x8B00		/* Commit pending changes to driver */
#define SIOCGIWNAME	0x8B01		/* get name == wireless protocol */
/* SIOCGIWNAME is used to verify the presence of Wireless Extensions.
 * Common values : "IEEE 802.11-DS", "IEEE 802.11-FH", "IEEE 802.11b"...
 * Don't put the name of your driver there, it's useless. */

/* Basic operations */
#define SIOCSIWNWID	0x8B02		/* set network id (pre-802.11) */
#define SIOCGIWNWID	0x8B03		/* get network id (the cell) */
#define SIOCSIWFREQ	0x8B04		/* set channel/frequency (Hz) */
#define SIOCGIWFREQ	0x8B05		/* get channel/frequency (Hz) */
#define SIOCSIWMODE	0x8B06		/* set operation mode */
#define SIOCGIWMODE	0x8B07		/* get operation mode */
#define SIOCSIWSENS	0x8B08		/* set sensitivity (dBm) */
#define SIOCGIWSENS	0x8B09		/* get sensitivity (dBm) */

/* Informative stuff */
#define SIOCSIWRANGE	0x8B0A		/* Unused */
#define SIOCGIWRANGE	0x8B0B		/* Get range of parameters */
#define SIOCSIWPRIV	0x8B0C		/* Unused */
#define SIOCGIWPRIV	0x8B0D		/* get private ioctl interface info */
#define SIOCSIWSTATS	0x8B0E		/* Unused */
#define SIOCGIWSTATS	0x8B0F		/* Get /proc/net/wireless stats */
/* SIOCGIWSTATS is strictly used between user space and the kernel, and
 * is never passed to the driver (i.e. the driver will never see it). */

/* Spy support (statistics per MAC address - used for Mobile IP support) */
#define SIOCSIWSPY	0x8B10		/* set spy addresses */
#define SIOCGIWSPY	0x8B11		/* get spy info (quality of link) */
#define SIOCSIWTHRSPY	0x8B12		/* set spy threshold (spy event) */
#define SIOCGIWTHRSPY	0x8B13		/* get spy threshold */

/* Access Point manipulation */
#define SIOCSIWAP	0x8B14		/* set access point MAC addresses */
#define SIOCGIWAP	0x8B15		/* get access point MAC addresses */
#define SIOCGIWAPLIST	0x8B17		/* Deprecated in favor of scanning */
#define SIOCSIWSCAN	0x8B18		/* trigger scanning (list cells) */
#define SIOCGIWSCAN	0x8B19		/* get scanning results */

/* 802.11 specific support */
#define SIOCSIWESSID	0x8B1A		/* set ESSID (network name) */
#define SIOCGIWESSID	0x8B1B		/* get ESSID */
#define SIOCSIWNICKN	0x8B1C		/* set node name/nickname */
#define SIOCGIWNICKN	0x8B1D		/* 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 for RANGE... */

/* Other parameters useful in 802.11 and some other devices */
#define SIOCSIWRATE	0x8B20		/* set default bit rate (bps) */
#define SIOCGIWRATE	0x8B21		/* get default bit rate (bps) */
#define SIOCSIWRTS	0x8B22		/* set RTS/CTS threshold (bytes) */
#define SIOCGIWRTS	0x8B23		/* get RTS/CTS threshold (bytes) */
#define SIOCSIWFRAG	0x8B24		/* set fragmentation thr (bytes) */
#define SIOCGIWFRAG	0x8B25		/* get fragmentation thr (bytes) */
#define SIOCSIWTXPOW	0x8B26		/* set transmit power (dBm) */
#define SIOCGIWTXPOW	0x8B27		/* get transmit power (dBm) */
#define SIOCSIWRETRY	0x8B28		/* set retry limits and lifetime */
#define SIOCGIWRETRY	0x8B29		/* get retry limits and lifetime */

/* Encoding stuff (scrambling, hardware security, WEP...) */
#define SIOCSIWENCODE	0x8B2A		/* set encoding token & mode */
#define SIOCGIWENCODE	0x8B2B		/* get encoding token & mode */
/* Power saving stuff (power management, unicast and multicast) */
#define SIOCSIWPOWER	0x8B2C		/* set Power Management settings */
#define SIOCGIWPOWER	0x8B2D		/* get Power Management settings */

/* WPA : Generic IEEE 802.11 informatiom element (e.g., for WPA/RSN/WMM).
 * This ioctl uses struct iw_point and data buffer that includes IE id and len
 * fields. More than one IE may be included in the request. Setting the generic
 * IE to empty buffer (len=0) removes the generic IE from the driver. Drivers
 * are allowed to generate their own WPA/RSN IEs, but in these cases, drivers
 * are required to report the used IE as a wireless event, e.g., when
 * associating with an AP. */
#define SIOCSIWGENIE	0x8B30		/* set generic IE */
#define SIOCGIWGENIE	0x8B31		/* get generic IE */

/* WPA : IEEE 802.11 MLME requests */
#define SIOCSIWMLME	0x8B16		/* request MLME operation; uses
					 * struct iw_mlme */
/* WPA : Authentication mode parameters */
#define SIOCSIWAUTH	0x8B32		/* set authentication mode params */
#define SIOCGIWAUTH	0x8B33		/* get authentication mode params */

/* WPA : Extended version of encoding configuration */
#define SIOCSIWENCODEEXT 0x8B34		/* set encoding token & mode */
#define SIOCGIWENCODEEXT 0x8B35		/* get encoding token & mode */

/* WPA2 : PMKSA cache management */
#define SIOCSIWPMKSA	0x8B36		/* PMKSA cache operation */

/* -------------------- DEV PRIVATE IOCTL LIST -------------------- */

/* These 32 ioctl are wireless device private, for 16 commands.
 * Each driver is free to use them for whatever purpose it chooses,
 * however the driver *must* export the description of those ioctls
 * with SIOCGIWPRIV and *must* use arguments as defined below.
 * If you don't follow those rules, DaveM is going to hate you (reason :
 * it make mixed 32/64bit operation impossible).
 */
#define SIOCIWFIRSTPRIV	0x8BE0
#define SIOCIWLASTPRIV	0x8BFF
/* Previously, we were using SIOCDEVPRIVATE, but we now have our
 * separate range because of collisions with other tools such as
 * 'mii-tool'.
 * We now have 32 commands, so a bit more space ;-).
 * Also, all 'even' commands are only usable by root and don't return the
 * content of ifr/iwr to user (but you are not obliged to use the set/get
 * convention, just use every other two command). More details in iwpriv.c.
 * And I repeat : you are not forced to use them with iwpriv, but you
 * must be compliant with it.
 */

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

/* The first and the last (range) */
#define SIOCIWFIRST	0x8B00
#define SIOCIWLAST	SIOCIWLASTPRIV		/* 0x8BFF */
#define IW_IOCTL_IDX(cmd)	((cmd) - SIOCIWFIRST)
#define IW_HANDLER(id, func)			\
	[IW_IOCTL_IDX(id)] = func

/* Odd : get (world access), even : set (root access) */
#define IW_IS_SET(cmd)	(!((cmd) & 0x1))
#define IW_IS_GET(cmd)	((cmd) & 0x1)

/* ----------------------- WIRELESS EVENTS ----------------------- */
/* Those are *NOT* ioctls, do not issue request on them !!! */
/* Most events use the same identifier as ioctl requests */

#define IWEVTXDROP	0x8C00		/* Packet dropped to excessive retry */
#define IWEVQUAL	0x8C01		/* Quality part of statistics (scan) */
#define IWEVCUSTOM	0x8C02		/* Driver specific ascii string */
#define IWEVREGISTERED	0x8C03		/* Discovered a new node (AP mode) */
#define IWEVEXPIRED	0x8C04		/* Expired a node (AP mode) */
#define IWEVGENIE	0x8C05		/* Generic IE (WPA, RSN, WMM, ..)
					 * (scan results); This includes id and
					 * length fields. One IWEVGENIE may
					 * contain more than one IE. Scan
					 * results may contain one or more
					 * IWEVGENIE events. */
#define IWEVMICHAELMICFAILURE 0x8C06	/* Michael MIC failure
					 * (struct iw_michaelmicfailure)
					 */
#define IWEVASSOCREQIE	0x8C07		/* IEs used in (Re)Association Request.
					 * The data includes id and length
					 * fields and may contain more than one
					 * IE. This event is required in
					 * Managed mode if the driver
					 * generates its own WPA/RSN IE. This
					 * should be sent just before
					 * IWEVREGISTERED event for the
					 * association. */
#define IWEVASSOCRESPIE	0x8C08		/* IEs used in (Re)Association
					 * Response. The data includes id and
					 * length fields and may contain more
					 * than one IE. This may be sent
					 * between IWEVASSOCREQIE and
					 * IWEVREGISTERED events for the
					 * association. */
#define IWEVPMKIDCAND	0x8C09		/* PMKID candidate for RSN
					 * pre-authentication
					 * (struct iw_pmkid_cand) */

#define IWEVFIRST	0x8C00
#define IW_EVENT_IDX(cmd)	((cmd) - IWEVFIRST)

/* ------------------------- 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 SIOCIWFIRSTPRIV -> SIOCIWLASTPRIV
 */

#define IW_PRIV_TYPE_MASK	0x7000	/* Type of arguments */
#define IW_PRIV_TYPE_NONE	0x0000
#define IW_PRIV_TYPE_BYTE	0x1000	/* Char as number */
#define IW_PRIV_TYPE_CHAR	0x2000	/* Char as character */
#define IW_PRIV_TYPE_INT	0x4000	/* 32 bits int */
#define IW_PRIV_TYPE_FLOAT	0x5000	/* struct iw_freq */
#define IW_PRIV_TYPE_ADDR	0x6000	/* struct sockaddr */

#define IW_PRIV_SIZE_FIXED	0x0800	/* Variable or fixed number of args */

#define IW_PRIV_SIZE_MASK	0x07FF	/* 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 iwreq struct...
 */

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

/* Maximum frequencies in the range struct */
#define IW_MAX_FREQUENCIES	32
/* 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 channel anyway... */

/* Maximum bit rates in the range struct */
#define IW_MAX_BITRATES		32

/* Maximum tx powers in the range struct */
#define IW_MAX_TXPOWER		8
/* Note : if you more than 8 TXPowers, just set the max and min or
 * a few of them in the struct iw_range. */

/* Maximum of address that you may set with SPY */
#define IW_MAX_SPY		8

/* Maximum of address that you may get in the
   list of access points in range */
#define IW_MAX_AP		64

/* Maximum size of the ESSID and NICKN strings */
#define IW_ESSID_MAX_SIZE	32

/* Modes of operation */
#define IW_MODE_AUTO	0	/* Let the driver decides */
#define IW_MODE_ADHOC	1	/* Single cell network */
#define IW_MODE_INFRA	2	/* Multi cell network, roaming, ... */
#define IW_MODE_MASTER	3	/* Synchronisation master or Access Point */
#define IW_MODE_REPEAT	4	/* Wireless Repeater (forwarder) */
#define IW_MODE_SECOND	5	/* Secondary master/repeater (backup) */
#define IW_MODE_MONITOR	6	/* Passive monitor (listen only) */
#define IW_MODE_MESH	7	/* Mesh (IEEE 802.11s) network */

/* Statistics flags (bitmask in updated) */
#define IW_QUAL_QUAL_UPDATED	0x01	/* Value was updated since last read */
#define IW_QUAL_LEVEL_UPDATED	0x02
#define IW_QUAL_NOISE_UPDATED	0x04
#define IW_QUAL_ALL_UPDATED	0x07
#define IW_QUAL_DBM		0x08	/* Level + Noise are dBm */
#define IW_QUAL_QUAL_INVALID	0x10	/* Driver doesn't provide value */
#define IW_QUAL_LEVEL_INVALID	0x20
#define IW_QUAL_NOISE_INVALID	0x40
#define IW_QUAL_RCPI		0x80	/* Level + Noise are 802.11k RCPI */
#define IW_QUAL_ALL_INVALID	0x70

/* Frequency flags */
#define IW_FREQ_AUTO		0x00	/* Let the driver decides */
#define IW_FREQ_FIXED		0x01	/* Force a specific value */

/* Maximum number of size of encoding token available
 * they are listed in the range structure */
#define IW_MAX_ENCODING_SIZES	8

/* Maximum size of the encoding token in bytes */
#define IW_ENCODING_TOKEN_MAX	64	/* 512 bits (for now) */

/* Flags for encoding (along with the token) */
#define IW_ENCODE_INDEX		0x00FF	/* Token index (if needed) */
#define IW_ENCODE_FLAGS		0xFF00	/* Flags defined below */
#define IW_ENCODE_MODE		0xF000	/* Modes defined below */
#define IW_ENCODE_DISABLED	0x8000	/* Encoding disabled */
#define IW_ENCODE_ENABLED	0x0000	/* Encoding enabled */
#define IW_ENCODE_RESTRICTED	0x4000	/* Refuse non-encoded packets */
#define IW_ENCODE_OPEN		0x2000	/* Accept non-encoded packets */
#define IW_ENCODE_NOKEY		0x0800  /* Key is write only, so not present */
#define IW_ENCODE_TEMP		0x0400  /* Temporary key */

/* Power management flags available (along with the value, if any) */
#define IW_POWER_ON		0x0000	/* No details... */
#define IW_POWER_TYPE		0xF000	/* Type of parameter */
#define IW_POWER_PERIOD		0x1000	/* Value is a period/duration of  */
#define IW_POWER_TIMEOUT	0x2000	/* Value is a timeout (to go asleep) */
#define IW_POWER_MODE		0x0F00	/* Power Management mode */
#define IW_POWER_UNICAST_R	0x0100	/* Receive only unicast messages */
#define IW_POWER_MULTICAST_R	0x0200	/* Receive only multicast messages */
#define IW_POWER_ALL_R		0x0300	/* Receive all messages though PM */
#define IW_POWER_FORCE_S	0x0400	/* Force PM procedure for sending unicast */
#define IW_POWER_REPEATER	0x0800	/* Repeat broadcast messages in PM period */
#define IW_POWER_MODIFIER	0x000F	/* Modify a parameter */
#define IW_POWER_MIN		0x0001	/* Value is a minimum  */
#define IW_POWER_MAX		0x0002	/* Value is a maximum */
#define IW_POWER_RELATIVE	0x0004	/* Value is not in seconds/ms/us */

/* Transmit Power flags available */
#define IW_TXPOW_TYPE		0x00FF	/* Type of value */
#define IW_TXPOW_DBM		0x0000	/* Value is in dBm */
#define IW_TXPOW_MWATT		0x0001	/* Value is in mW */
#define IW_TXPOW_RELATIVE	0x0002	/* Value is in arbitrary units */
#define IW_TXPOW_RANGE		0x1000	/* Range of value between min/max */

/* Retry limits and lifetime flags available */
#define IW_RETRY_ON		0x0000	/* No details... */
#define IW_RETRY_TYPE		0xF000	/* Type of parameter */
#define IW_RETRY_LIMIT		0x1000	/* Maximum number of retries*/
#define IW_RETRY_LIFETIME	0x2000	/* Maximum duration of retries in us */
#define IW_RETRY_MODIFIER	0x00FF	/* Modify a parameter */
#define IW_RETRY_MIN		0x0001	/* Value is a minimum  */
#define IW_RETRY_MAX		0x0002	/* Value is a maximum */
#define IW_RETRY_RELATIVE	0x0004	/* Value is not in seconds/ms/us */
#define IW_RETRY_SHORT		0x0010	/* Value is for short packets  */
#define IW_RETRY_LONG		0x0020	/* Value is for long packets */

/* Scanning request flags */
#define IW_SCAN_DEFAULT		0x0000	/* Default scan of the driver */
#define IW_SCAN_ALL_ESSID	0x0001	/* Scan all ESSIDs */
#define IW_SCAN_THIS_ESSID	0x0002	/* Scan only this ESSID */
#define IW_SCAN_ALL_FREQ	0x0004	/* Scan all Frequencies */
#define IW_SCAN_THIS_FREQ	0x0008	/* Scan only this Frequency */
#define IW_SCAN_ALL_MODE	0x0010	/* Scan all Modes */
#define IW_SCAN_THIS_MODE	0x0020	/* Scan only this Mode */
#define IW_SCAN_ALL_RATE	0x0040	/* Scan all Bit-Rates */
#define IW_SCAN_THIS_RATE	0x0080	/* Scan only this Bit-Rate */
/* struct iw_scan_req scan_type */
#define IW_SCAN_TYPE_ACTIVE 0
#define IW_SCAN_TYPE_PASSIVE 1
/* Maximum size of returned data */
#define IW_SCAN_MAX_DATA	4096	/* In bytes */

/* Scan capability flags - in (struct iw_range *)->scan_capa */
#define IW_SCAN_CAPA_NONE		0x00
#define IW_SCAN_CAPA_ESSID		0x01
#define IW_SCAN_CAPA_BSSID		0x02
#define IW_SCAN_CAPA_CHANNEL	0x04
#define IW_SCAN_CAPA_MODE		0x08
#define IW_SCAN_CAPA_RATE		0x10
#define IW_SCAN_CAPA_TYPE		0x20
#define IW_SCAN_CAPA_TIME		0x40

```

為了更了解如何透過wireless取得無線網路相關資訊，我們來看一個取得essid的範例:
```Clike=
struct iwreq iw_req;

int fd = 0;
int ret = 0;
    
// Give interface name to iw_req.
const char *iface_name = "wlan2";

uint8_t buffer[ESSID_LENGTH] = {0};

strcpy(iw_req.ifr_ifrn.ifrn_name, iface_name);

fd = socket(AF_INET, SOCK_DGRAM, 0);

// Alloc an new space to essid of iw_req of structure.
iw_req.u.essid.pointer = buffer;
iw_req.u.essid.length = sizeof(char)*ESSID_LENGTH;

// Get essid on the interface name.
ret = ioctl(fd, SIOCGIWESSID, &iw_req);
if (ret == -1) {
    return false;
}
    
// Print essid name.
printf("%s\n", (char*)iw_req.u.essid.pointer);
    
close(fd);
```

上述程式有一個重要的structure:
```Clike=
struct iwreq iw_req;
```

讓我們來看看該structure原型:
 ```Clike=
 /*
 * The structure to exchange data for ioctl.
 * This structure is the same as 'struct ifreq', but (re)defined for
 * convenience...
 * Do I need to remind you about structure size (32 octets) ?
 */
struct iwreq {
	union
	{
		char	ifrn_name[IFNAMSIZ];	/* if name, e.g. "eth0" */
	} ifr_ifrn;

	/* Data part (defined just above) */
	union iwreq_data	u;
};
 ```
 
 該結構採用ifrn_name儲存interface name，並將資料部分使用iwreq_data儲存。
 
 也就是說，我們可以將目標interface name放入ifrn_name，並透過ioctl將返回結果放入iwreq_data。
 
 iwreq_data是一個union 結構，讓我們看看他的原型:
 ```Clike=
 /* ------------------------ IOCTL REQUEST ------------------------ */
/*
 * This structure defines the payload of an ioctl, and is used 
 * below.
 *
 * Note that this structure should fit on the memory footprint
 * of iwreq (which is the same as ifreq), which mean a max size of
 * 16 octets = 128 bits. Warning, pointers might be 64 bits wide...
 * You should check this when increasing the structures defined
 * above in this file...
 */
union	iwreq_data
{
	/* Config - generic */
	char		name[IFNAMSIZ];
	/* Name : used to verify the presence of  wireless extensions.
	 * Name of the protocol/provider... */

	struct iw_point	essid;		/* Extended network name */
	struct iw_param	nwid;		/* network id (or domain - the cell) */
	struct iw_freq	freq;		/* frequency or channel :
					 * 0-1000 = channel
					 * > 1000 = frequency in Hz */

	struct iw_param	sens;		/* signal level threshold */
	struct iw_param	bitrate;	/* default bit rate */
	struct iw_param	txpower;	/* default transmit power */
	struct iw_param	rts;		/* RTS threshold threshold */
	struct iw_param	frag;		/* Fragmentation threshold */
	__u32		mode;		/* Operation mode */
	struct iw_param	retry;		/* Retry limits & lifetime */

	struct iw_point	encoding;	/* Encoding stuff : tokens */
	struct iw_param	power;		/* PM duration/timeout */
	struct iw_quality qual;		/* Quality part of statistics */

	struct sockaddr	ap_addr;	/* Access point address */
	struct sockaddr	addr;		/* Destination address (hw/mac) */

	struct iw_param	param;		/* Other small parameters */
	struct iw_point	data;		/* Other large parameters */
};
 ```

所有structure共享一塊記憶體空間。如上範例，我們請求了essid資訊。於是，當處理回傳結果時候，就可以透過
```Clike=
struct iw_point	essid;
```

union iwreq_data轉型成struct iw_point essid。
```Clike=
/*
 *	For all data larger than 16 octets, we need to use a
 *	pointer to memory allocated in user space.
 */
struct	iw_point
{
  void __user	*pointer;	/* Pointer to the data  (in user space) */
  __u16		length;		/* number of fields or size in bytes */
  __u16		flags;		/* Optional params */
};
```

因此我們可以直接將pointer轉型成essid名稱。
```Clike=
printf("%s\n", (char*)iw_req.u.essid.pointer);
```

---

Wireless.h 可以快速且方便取得wireless介面卡的所有資訊。若先透過netdevice取得interface的基本資訊，再利用wireless.h更進一步取得無線網路資訊，可製作簡單的ifconfig功能，如下範例:

[pi-router-os-core](https://github.com/sss22213/pi-router-os-core)

![](https://i.imgur.com/MA68dPK.png)
