wireless.h - HackMD

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)