[802.11] Add support for 802.11 devices with software MAC layer

This is required for all modern 802.11 devices, and allows drivers
to be written for them with minimally more effort than is required
for a wired NIC.

Signed-off-by: Michael Brown <mcb30@etherboot.org>
Modified-by: Michael Brown <mcb30@etherboot.org>

1 files changed, 1174 insertions, 0 deletions

diff --git a/src/include/gpxe/ieee80211.h b/src/include/gpxe/ieee80211.h
new file mode 100644
index 00000000..e2d25191
--- /dev/null
+++ b/src/include/gpxe/ieee80211.h
@@ -0,0 +1,1174 @@
+#ifndef _GPXE_IEEE80211_H
+#define _GPXE_IEEE80211_H
+
+#include <gpxe/if_ether.h>	/* for ETH_ALEN */
+
+/** @file
+ * Constants and data structures defined in IEEE 802.11, subsetted
+ * according to what gPXE knows how to use.
+ */
+
+FILE_LICENCE(GPL2_OR_LATER);
+
+/* ---------- Maximum lengths of things ---------- */
+
+/**
+ * @defgroup ieee80211_maxlen Maximum lengths in the 802.11 protocol
+ * @{
+ */
+
+/** Maximum length of frame payload
+ *
+ * This does not include cryptographic overhead, which can be up to 20
+ * bytes, but it DOES include the 802.2 LLC/SNAP headers that are used
+ * on data frames (but not management frames).
+ */
+#define IEEE80211_MAX_DATA_LEN          2304
+
+/** Length of LLC/SNAP headers on data frames */
+#define IEEE80211_LLC_HEADER_LEN	8
+
+/** Maximum cryptographic overhead before encrypted data */
+#define IEEE80211_MAX_CRYPTO_HEADER	8
+
+/** Maximum cryptographic overhead after encrypted data */
+#define IEEE80211_MAX_CRYPTO_TRAILER    12
+
+/** Total maximum cryptographic overhead */
+#define IEEE80211_MAX_CRYPTO_OVERHEAD	20
+
+/** Bytes of network-layer data that can go into a regular data frame */
+#define IEEE80211_MAX_FRAME_DATA	2296
+
+/** Frame header length for frames we might work with
+ *
+ * QoS adds a two-byte field on top of this, and APs communicating
+ * with each other in Wireless Distribution System (WDS) mode add an
+ * extra 6-byte MAC address field, but we do not work with such
+ * frames.
+ */
+#define IEEE80211_TYP_FRAME_HEADER_LEN	24
+
+/** Theoretical maximum frame header length
+ *
+ * This includes the QoS and WDS Addr4 fields that we should never
+ * see.
+ */
+#define IEEE80211_MAX_FRAME_HEADER_LEN	32
+
+/** Maximum combined frame length
+ *
+ * The biggest frame will include 32 frame header bytes, 20 bytes of
+ * crypto overhead, and 2304 data bytes.
+ */
+#define IEEE80211_MAX_FRAME_LEN         2356
+
+/** Maximum length of an ESSID */
+#define IEEE80211_MAX_SSID_LEN          32
+
+/** @} */
+
+
+/* ---------- Frame Control defines ---------- */
+
+/**
+ * @defgroup ieee80211_fc 802.11 Frame Control field bits
+ * @{
+ */
+
+/** 802.11 Frame Control field, Version bitmask */
+#define IEEE80211_FC_VERSION	0x0003
+
+/** Expected value of Version bits in Frame Control */
+#define  IEEE80211_THIS_VERSION  0x0000
+
+
+/** 802.11 Frame Control field, Frame Type bitmask */
+#define IEEE80211_FC_TYPE	0x000C
+
+/** Type value for management (layer-2) frames */
+#define  IEEE80211_TYPE_MGMT     0x0000
+
+/** Type value for control (layer-1, hardware-managed) frames */
+#define  IEEE80211_TYPE_CTRL     0x0004
+
+/** Type value for data frames */
+#define  IEEE80211_TYPE_DATA     0x0008
+
+
+/** 802.11 Frame Control field, Frame Subtype bitmask */
+#define IEEE80211_FC_SUBTYPE	0x00F0
+
+/** Subtype value for association-request management frames
+ *
+ * Association request frames are sent after authentication from the
+ * client to the Access Point to establish the client as part of the
+ * Access Point's network.
+ */
+#define  IEEE80211_STYPE_ASSOC_REQ    0x0000
+
+/** Subtype value for association-response management frames
+ *
+ * Association response frames are sent by the Access Point to confirm
+ * or deny the association requested in an association request frame.
+ */
+#define  IEEE80211_STYPE_ASSOC_RESP   0x0010
+
+/** Subtype value for reassociation-request management frames
+ *
+ * Reassociation request frames are sent by clients wishing to change
+ * from one Access Point to another while roaming within the same
+ * extended network (same ESSID).
+ */
+#define  IEEE80211_STYPE_REASSOC_REQ  0x0020
+
+/** Subtype value for reassociation-response management frames
+ *
+ * Reassociation response frames are sent by the Access Point to
+ * confirm or deny the swap requested in a reassociation request
+ * frame.
+ */
+#define  IEEE80211_STYPE_REASSOC_RESP 0x0030
+
+/** Subtype value for probe-request management frames
+ *
+ * Probe request frames are sent by clients to request that all Access
+ * Points on the sending channel, or all belonging to a particular
+ * ESSID, identify themselves by BSSID, supported transfer rates, RF
+ * configuration, and other capabilities.
+ */
+#define  IEEE80211_STYPE_PROBE_REQ    0x0040
+
+/** Subtype value for probe-response management frames
+ *
+ * Probe response frames are sent by Access Points in response to
+ * probe request frames, providing the requested information.
+ */
+#define  IEEE80211_STYPE_PROBE_RESP   0x0050
+
+/** Subtype value for beacon management frames
+ *
+ * Beacon frames are sent by Access Points at regular intervals,
+ * usually ten per second, on the channel on which they communicate.
+ * They can be used to probe passively for access points on a channel
+ * where local regulatory restrictions prohibit active scanning, or
+ * due to their regularity as a mechanism to determine the fraction of
+ * packets that are being dropped.
+ */
+#define  IEEE80211_STYPE_BEACON       0x0080
+
+/** Subtype value for disassociation management frames
+ *
+ * Disassociation frames are sent by either a client or an Access
+ * Point to unequivocally terminate the association between the two.
+ * They may be sent by clients upon leaving the network, or by an
+ * Access Point upon reconfiguration, among other reasons; they are
+ * usually more "polite" than deauthentication frames.
+ */
+#define  IEEE80211_STYPE_DISASSOC     0x00A0
+
+/** Subtype value for authentication management frames
+ *
+ * Authentication frames are exchanged between a client and an Access
+ * Point before association may be performed. Confusingly, in the most
+ * common authentication method (Open System) no security tokens are
+ * exchanged at all. Modern 802.11 security handshaking takes place
+ * after association.
+ */
+#define  IEEE80211_STYPE_AUTH         0x00B0
+
+/** Subtype value for deauthentication management frames
+ *
+ * Deauthentication frames are sent by either a client or an Access
+ * Point to terminate the authentication (and therefore also the
+ * association) between the two. They are generally more forceful than
+ * disassociation frames, sent for such reasons as a failure to
+ * set up security properly after associating.
+ */
+#define  IEEE80211_STYPE_DEAUTH       0x00C0
+
+/** Subtype value for action management frames
+ *
+ * Action frames are used to implement spectrum management and QoS
+ * features that gPXE currently does not support.
+ */
+#define  IEEE80211_STYPE_ACTION	      0x00D0
+
+
+/** Subtype value for RTS (request to send) control frames */
+#define  IEEE80211_STYPE_RTS          0x00B0
+
+/** Subtype value for CTS (clear to send) control frames */
+#define  IEEE80211_STYPE_CTS          0x00C0
+
+/** Subtype value for ACK (acknowledgement) control frames */
+#define  IEEE80211_STYPE_ACK          0x00D0
+
+
+/** Subtype value for ordinary data frames, with no QoS or CF add-ons */
+#define  IEEE80211_STYPE_DATA         0x0000
+
+/** Subtype value for data frames containing no data */
+#define  IEEE80211_STYPE_NODATA       0x0040
+
+
+/** 802.11 Frame Control field: To Data System flag
+ *
+ * This is set on data frames sent to an Access Point.
+ */
+#define IEEE80211_FC_TODS       0x0100
+
+/** 802.11 Frame Control field: From Data System flag
+ *
+ * This is set on data frames sent from an Access Point. If both TODS
+ * and FROMDS are set, the frame header is a 4-address format used for
+ * inter-Access Point communication.
+ */
+#define IEEE80211_FC_FROMDS     0x0200
+
+/** 802.11 Frame Control field: More Fragments flag */
+#define IEEE80211_FC_MORE_FRAG  0x0400
+
+/** 802.11 Frame Control field: Retransmission flag */
+#define IEEE80211_FC_RETRY      0x0800
+
+/** 802.11 Frame Control field: Power Managed flag
+ *
+ * This is set on any frame sent by a low-power station that will go
+ * into a power-saving mode immediately after this frame. Access
+ * Points are not allowed to act as low-power stations.
+ */
+#define IEEE80211_FC_PWR_MGMT   0x1000
+
+/** 802.11 Frame Control field: More Data flag
+ *
+ * This is set on any frame sent by a station that has more data
+ * queued to be sent than is in the frame.
+ */
+#define IEEE80211_FC_MORE_DATA  0x2000
+
+/** 802.11 Frame Control field: Protected flag
+ *
+ * This is set on frames in which data is encrypted (by any method).
+ */
+#define IEEE80211_FC_PROTECTED  0x4000
+
+/** 802.11 Frame Control field: Ordered flag [?] */
+#define IEEE80211_FC_ORDER      0x8000
+
+/** @} */
+
+
+/* ---------- Sequence Control defines ---------- */
+
+/**
+ * @defgroup ieee80211_seq 802.11 Sequence Control field handling
+ * @{
+ */
+
+/** Extract sequence number from 802.11 Sequence Control field */
+#define IEEE80211_SEQNR( seq )		( ( seq ) >> 4 )
+
+/** Extract fragment number from 802.11 Sequence Control field */
+#define IEEE80211_FRAG( seq )		( ( seq ) & 0x000F )
+
+/** Make 802.11 Sequence Control field from sequence and fragment numbers */
+#define IEEE80211_MAKESEQ( seqnr, frag )	\
+	( ( ( ( seqnr ) & 0xFFF ) << 4 ) | ( ( frag ) & 0xF ) )
+
+/** @} */
+
+
+/* ---------- Frame header formats ---------- */
+
+/**
+ * @defgroup ieee80211_hdr 802.11 frame header formats
+ * @{
+ */
+
+/** An 802.11 data or management frame without QoS or WDS header fields */
+struct ieee80211_frame
+{
+	u16 fc;			/**< 802.11 Frame Control field */
+	u16 duration;		/**< Microseconds to reserve link */
+	u8 addr1[ETH_ALEN];	/**< Address 1 (immediate receiver) */
+	u8 addr2[ETH_ALEN];	/**< Address 2 (immediate sender) */
+	u8 addr3[ETH_ALEN];	/**< Address 3 (often "forward to") */
+	u16 seq;		/**< 802.11 Sequence Control field */
+	u8 data[0];		/**< Beginning of frame data */
+} __attribute__((packed));
+
+/** The 802.2 LLC/SNAP header sent before actual data in a data frame
+ *
+ * This header is not acknowledged in the 802.11 standard at all; it
+ * is treated just like data for MAC-layer purposes, including
+ * fragmentation and encryption. It is actually two headers
+ * concatenated: a three-byte 802.2 LLC header indicating Subnetwork
+ * Accesss Protocol (SNAP) in both source and destination Service
+ * Access Point (SAP) fields, and a five-byte SNAP header indicating a
+ * zero OUI and two-byte Ethernet protocol type field.
+ *
+ * Thus, an eight-byte header in which six of the bytes are redundant.
+ * Lovely, isn't it?
+ */
+struct ieee80211_llc_snap_header
+{
+	/* LLC part: */
+	u8 dsap;		/**< Destination SAP ID */
+	u8 ssap;		/**< Source SAP ID */
+	u8 ctrl;		/**< Control information */
+
+	/* SNAP part: */
+	u8 oui[3];		/**< Organization code, usually 0 */
+	u16 ethertype;		/**< Ethernet Type field */
+} __attribute__((packed));
+
+/** Value for DSAP field in 802.2 LLC header for 802.11 frames: SNAP */
+#define IEEE80211_LLC_DSAP	0xAA
+
+/** Value for SSAP field in 802.2 LLC header for 802.11 frames: SNAP */
+#define IEEE80211_LLC_SSAP	0xAA
+
+/** Value for control field in 802.2 LLC header for 802.11 frames
+ *
+ * "Unnumbered Information".
+ */
+#define IEEE80211_LLC_CTRL	0x03
+
+
+/** 16-byte RTS frame format, with abbreviated header */
+struct ieee80211_rts
+{
+	u16 fc;			/**< 802.11 Frame Control field */
+	u16 duration;		/**< Microseconds to reserve link */
+	u8 addr1[ETH_ALEN];	/**< Address 1 (immediate receiver) */
+	u8 addr2[ETH_ALEN];	/**< Address 2 (immediate sender) */
+} __attribute__((packed));
+
+/** Length of 802.11 RTS control frame */
+#define IEEE80211_RTS_LEN	16
+
+/** 10-byte CTS or ACK frame format, with abbreviated header */
+struct ieee80211_cts_or_ack
+{
+	u16 fc;			/**< 802.11 Frame Control field */
+	u16 duration;		/**< Microseconds to reserve link */
+	u8 addr1[ETH_ALEN];	/**< Address 1 (immediate receiver) */
+} __attribute__((packed));
+
+#define ieee80211_cts ieee80211_cts_or_ack
+#define ieee80211_ack ieee80211_cts_or_ack
+
+/** Length of 802.11 CTS control frame */
+#define IEEE80211_CTS_LEN	10
+
+/** Length of 802.11 ACK control frame */
+#define IEEE80211_ACK_LEN	10
+
+/** @} */
+
+
+/* ---------- Capability bits, status and reason codes ---------- */
+
+/**
+ * @defgroup ieee80211_capab 802.11 management frame capability field bits
+ * @{
+ */
+
+/** Set if using an Access Point (managed mode) */
+#define IEEE80211_CAPAB_MANAGED       0x0001
+
+/** Set if operating in IBSS (no-AP, "Ad-Hoc") mode */
+#define IEEE80211_CAPAB_ADHOC         0x0002
+
+/** Set if we support Contention-Free Period operation */
+#define IEEE80211_CAPAB_CFPOLL        0x0004
+
+/** Set if we wish to be polled for Contention-Free operation */
+#define IEEE80211_CAPAB_CFPR          0x0008
+
+/** Set if the network is encrypted (by any method) */
+#define IEEE80211_CAPAB_PRIVACY       0x0010
+
+/** Set if PHY supports short preambles on 802.11b */
+#define IEEE80211_CAPAB_SHORT_PMBL    0x0020
+
+/** Set if PHY supports PBCC modulation */
+#define IEEE80211_CAPAB_PBCC          0x0040
+
+/** Set if we support Channel Agility */
+#define IEEE80211_CAPAB_CHAN_AGILITY  0x0080
+
+/** Set if we support spectrum management (DFS and TPC) on the 5GHz band */
+#define IEEE80211_CAPAB_SPECTRUM_MGMT 0x0100
+
+/** Set if we support Quality of Service enhancements */
+#define IEEE80211_CAPAB_QOS           0x0200
+
+/** Set if PHY supports short slot time on 802.11g */
+#define IEEE80211_CAPAB_SHORT_SLOT    0x0400
+
+/** Set if PHY supports APSD option */
+#define IEEE80211_CAPAB_APSD          0x0800
+
+/** Set if PHY supports DSSS/OFDM modulation (one way of 802.11 b/g mixing) */
+#define IEEE80211_CAPAB_DSSS_OFDM     0x2000
+
+/** Set if we support delayed block ACK */
+#define IEEE80211_CAPAB_DELAYED_BACK  0x4000
+
+/** Set if we support immediate block ACK */
+#define IEEE80211_CAPAB_IMMED_BACK    0x8000
+
+/** @} */
+
+
+/**
+ * @defgroup ieee80211_status 802.11 status codes
+ *
+ * These are returned to indicate an immediate denial of
+ * authentication or association. In gPXE, the lower 5 bits of the
+ * status code are encoded into the file-unique portion of an error
+ * code, the ERRFILE portion is always @c ERRFILE_net80211, and the
+ * POSIX error code is @c ECONNREFUSED for status 0-31 or @c
+ * EHOSTUNREACH for status 32-63.
+ *
+ * For a complete table with non-abbreviated error messages, see IEEE
+ * Std 802.11-2007, Table 7-23, p.94.
+ *
+ * @{
+ */
+
+#define IEEE80211_STATUS_SUCCESS		0
+#define IEEE80211_STATUS_FAILURE		1
+#define IEEE80211_STATUS_CAPAB_UNSUPP		10
+#define IEEE80211_STATUS_REASSOC_INVALID	11
+#define IEEE80211_STATUS_ASSOC_DENIED		12
+#define IEEE80211_STATUS_AUTH_ALGO_UNSUPP	13
+#define IEEE80211_STATUS_AUTH_SEQ_INVALID	14
+#define IEEE80211_STATUS_AUTH_CHALL_INVALID	15
+#define IEEE80211_STATUS_AUTH_TIMEOUT		16
+#define IEEE80211_STATUS_ASSOC_NO_ROOM		17
+#define IEEE80211_STATUS_ASSOC_NEED_RATE	18
+#define IEEE80211_STATUS_ASSOC_NEED_SHORT_PMBL	19
+#define IEEE80211_STATUS_ASSOC_NEED_PBCC	20
+#define IEEE80211_STATUS_ASSOC_NEED_CHAN_AGILITY 21
+#define IEEE80211_STATUS_ASSOC_NEED_SPECTRUM_MGMT 22
+#define IEEE80211_STATUS_ASSOC_BAD_POWER	23
+#define IEEE80211_STATUS_ASSOC_BAD_CHANNELS	24
+#define IEEE80211_STATUS_ASSOC_NEED_SHORT_SLOT	25
+#define IEEE80211_STATUS_ASSOC_NEED_DSSS_OFDM	26
+#define IEEE80211_STATUS_QOS_FAILURE		32
+#define IEEE80211_STATUS_QOS_NO_ROOM		33
+#define IEEE80211_STATUS_LINK_IS_HORRIBLE	34
+#define IEEE80211_STATUS_ASSOC_NEED_QOS		35
+#define IEEE80211_STATUS_REQUEST_DECLINED	37
+#define IEEE80211_STATUS_REQUEST_INVALID	38
+#define IEEE80211_STATUS_TS_NOT_CREATED_AGAIN	39
+#define IEEE80211_STATUS_INVALID_IE		40
+#define IEEE80211_STATUS_GROUP_CIPHER_INVALID	41
+#define IEEE80211_STATUS_PAIR_CIPHER_INVALID	42
+#define IEEE80211_STATUS_AKMP_INVALID		43
+#define IEEE80211_STATUS_RSN_VERSION_UNSUPP	44
+#define IEEE80211_STATUS_RSN_CAPAB_INVALID	45
+#define IEEE80211_STATUS_CIPHER_REJECTED	46
+#define IEEE80211_STATUS_TS_NOT_CREATED_WAIT	47
+#define IEEE80211_STATUS_DIRECT_LINK_FORBIDDEN	48
+#define IEEE80211_STATUS_DEST_NOT_PRESENT	49
+#define IEEE80211_STATUS_DEST_NOT_QOS		50
+#define IEEE80211_STATUS_ASSOC_LISTEN_TOO_HIGH	51
+
+/** @} */
+
+
+
+/**
+ * @defgroup ieee80211_reason 802.11 reason codes
+ *
+ * These are returned to indicate the reason for a deauthentication or
+ * disassociation sent (usually) after authentication or association
+ * had succeeded.  In gPXE, the lower 5 bits of the reason code are
+ * encoded into the file-unique portion of an error code, the ERRFILE
+ * portion is always @c ERRFILE_net80211, and the POSIX error code is
+ * @c ECONNRESET for reason 0-31 or @c ENETRESET for reason 32-63.
+ *
+ * For a complete table with non-abbreviated error messages, see IEEE
+ * Std 802.11-2007, Table 7-22, p.92.
+ *
+ * @{
+ */
+
+#define IEEE80211_REASON_NONE			0
+#define IEEE80211_REASON_UNSPECIFIED		1
+#define IEEE80211_REASON_AUTH_NO_LONGER_VALID	2
+#define IEEE80211_REASON_LEAVING		3
+#define IEEE80211_REASON_INACTIVITY		4
+#define IEEE80211_REASON_OUT_OF_RESOURCES	5
+#define IEEE80211_REASON_NEED_AUTH		6
+#define IEEE80211_REASON_NEED_ASSOC		7
+#define IEEE80211_REASON_LEAVING_TO_ROAM	8
+#define IEEE80211_REASON_REASSOC_INVALID	9
+#define IEEE80211_REASON_BAD_POWER		10
+#define IEEE80211_REASON_BAD_CHANNELS		11
+#define IEEE80211_REASON_INVALID_IE		13
+#define IEEE80211_REASON_MIC_FAILURE		14
+#define IEEE80211_REASON_4WAY_TIMEOUT		15
+#define IEEE80211_REASON_GROUPKEY_TIMEOUT	16
+#define IEEE80211_REASON_4WAY_INVALID		17
+#define IEEE80211_REASON_GROUP_CIPHER_INVALID	18
+#define IEEE80211_REASON_PAIR_CIPHER_INVALID	19
+#define IEEE80211_REASON_AKMP_INVALID		20
+#define IEEE80211_REASON_RSN_VERSION_INVALID	21
+#define IEEE80211_REASON_RSN_CAPAB_INVALID	22
+#define IEEE80211_REASON_8021X_FAILURE		23
+#define IEEE80211_REASON_CIPHER_REJECTED	24
+#define IEEE80211_REASON_QOS_UNSPECIFIED	32
+#define IEEE80211_REASON_QOS_OUT_OF_RESOURCES	33
+#define IEEE80211_REASON_LINK_IS_HORRIBLE	34
+#define IEEE80211_REASON_INVALID_TXOP		35
+#define IEEE80211_REASON_REQUESTED_LEAVING	36
+#define IEEE80211_REASON_REQUESTED_NO_USE	37
+#define IEEE80211_REASON_REQUESTED_NEED_SETUP	38
+#define IEEE80211_REASON_REQUESTED_TIMEOUT	39
+#define IEEE80211_REASON_CIPHER_UNSUPPORTED	45
+
+/** @} */
+
+/* ---------- Information element declarations ---------- */
+
+/**
+ * @defgroup ieee80211_ie 802.11 information elements
+ *
+ * Many management frames include a section that amounts to a
+ * concatenation of these information elements, so that the sender can
+ * choose which information to send and the receiver can ignore the
+ * parts it doesn't understand. Each IE contains a two-byte header,
+ * one byte ID and one byte length, followed by IE-specific data. The
+ * length does not include the two-byte header. Information elements
+ * are required to be sorted by ID, but gPXE does not require that in
+ * those it receives.
+ *
+ * This group also includes a few inline functions to simplify common
+ * tasks in IE processing.
+ *
+ * @{
+ */
+
+/** Generic 802.11 information element header */
+struct ieee80211_ie_header {
+	u8 id;			/**< Information element ID */
+	u8 len;			/**< Information element length */
+} __attribute__ ((packed));
+
+
+/** 802.11 SSID information element */
+struct ieee80211_ie_ssid {
+	u8 id;			/**< SSID ID: 0 */
+	u8 len;			/**< SSID length */
+	char ssid[0];		/**< SSID data, not NUL-terminated */
+} __attribute__ ((packed));
+
+/** Information element ID for SSID information element */
+#define IEEE80211_IE_SSID	0
+
+
+/** 802.11 rates information element
+ *
+ * The first 8 rates go in an IE of type RATES (1), and any more rates
+ * go in one of type EXT_RATES (50). Each rate is a byte with the low
+ * 7 bits equal to the rate in units of 500 kbps, and the high bit set
+ * if and only if the rate is "basic" (must be supported by all
+ * connected stations).
+ */
+struct ieee80211_ie_rates {
+	u8 id;			/**< Rates ID: 1 or 50 */
+	u8 len;			/**< Number of rates */
+	u8 rates[0];		/**< Rates data, one rate per byte */
+} __attribute__ ((packed));
+
+/** Information element ID for rates information element */
+#define IEEE80211_IE_RATES	1
+
+/** Information element ID for extended rates information element */
+#define IEEE80211_IE_EXT_RATES	50
+
+
+/** 802.11 Direct Spectrum parameter information element
+ *
+ * This just contains the channel number. It has the fancy name
+ * because IEEE 802.11 also defines a frequency-hopping PHY that
+ * changes channels at regular intervals following a predetermined
+ * pattern; in practice nobody uses the FH PHY.
+ */
+struct ieee80211_ie_ds_param {
+	u8 id;			/**< DS parameter ID: 3 */
+	u8 len;			/**< DS parameter length: 1 */
+	u8 current_channel;	/**< Current channel number, 1-14 */
+} __attribute__ ((packed));
+
+/** Information element ID for Direct Spectrum parameter information element */
+#define IEEE80211_IE_DS_PARAM	3
+
+
+/** 802.11 Country information element regulatory extension triplet */
+struct ieee80211_ie_country_ext_triplet {
+	u8 reg_ext_id;		/**< Regulatory extension ID */
+	u8 reg_class_id;	/**< Regulatory class ID */
+	u8 coverage_class;	/**< Coverage class */
+} __attribute__ ((packed));
+
+/** 802.11 Country information element regulatory band triplet */
+struct ieee80211_ie_country_band_triplet {
+	u8 first_channel;	/**< Channel number for first channel in band */
+	u8 nr_channels;		/**< Number of contiguous channels in band */
+	u8 max_txpower;		/**< Maximum TX power in dBm */
+} __attribute__ ((packed));
+
+/** 802.11 Country information element regulatory triplet
+ *
+ * It is a band triplet if the first byte is 200 or less, and a
+ * regulatory extension triplet otherwise.
+ */
+union ieee80211_ie_country_triplet {
+	/** Differentiator between band and ext triplets */
+	u8 first;
+
+	/** Information about a band of channels */
+	struct ieee80211_ie_country_band_triplet band;
+
+	/** Regulatory extension information */
+	struct ieee80211_ie_country_ext_triplet ext;
+};
+
+/** 802.11 Country information element
+ *
+ * This contains some data about RF regulations.
+ */
+struct ieee80211_ie_country {
+	u8 id;			/**< Country information ID: 7 */
+	u8 len;			/**< Country information length: varies */
+	char name[2];		/**< ISO Alpha2 country code */
+	char in_out;		/**< 'I' for indoor, 'O' for outdoor */
+
+	/** List of regulatory triplets */
+	union ieee80211_ie_country_triplet triplet[0];
+} __attribute__ ((packed));
+
+/** Information element ID for Country information element */
+#define IEEE80211_IE_COUNTRY	7
+
+
+/** 802.11 Request information element
+ *
+ * This contains a list of information element types we would like to
+ * be included in probe response frames.
+ */
+struct ieee80211_ie_request {
+	u8 id;			/**< Request ID: 10 */
+	u8 len;			/**< Number of IEs requested */
+	u8 request[0];		/**< List of IEs requested */
+} __attribute__ ((packed));
+
+/** Information element ID for Request information element */
+#define IEEE80211_IE_REQUEST	10
+
+
+/** 802.11 Challenge Text information element
+ *
+ * This is used in authentication frames under Shared Key
+ * authentication.
+ */
+struct ieee80211_ie_challenge_text {
+	u8 id;			/**< Challenge Text ID: 16 */
+	u8 len;			/**< Challenge Text length: usually 128 */
+	u8 challenge_text[0];	/**< Challenge Text data */
+} __attribute__ ((packed));
+
+/** Information element ID for Challenge Text information element */
+#define IEEE80211_IE_CHALLENGE_TEXT	16
+
+
+/** 802.11 Power Constraint information element
+ *
+ * This is used to specify an additional power limitation on top of
+ * the Country requirements.
+ */
+struct ieee80211_ie_power_constraint {
+	u8 id;			/**< Power Constraint ID: 52 */
+	u8 len;			/**< Power Constraint length: 1 */
+	u8 power_constraint;	/**< Decrease in allowed TX power, dBm */
+} __attribute__ ((packed));
+
+/** Information element ID for Power Constraint information element */
+#define IEEE80211_IE_POWER_CONSTRAINT	52
+
+
+/** 802.11 Power Capability information element
+ *
+ * This is used in association request frames to indicate the extremes
+ * of our TX power abilities. It is required only if we indicate
+ * support for spectrum management.
+ */
+struct ieee80211_ie_power_capab {
+	u8 id;			/**< Power Capability ID: 33 */
+	u8 len;			/**< Power Capability length: 2 */
+	u8 min_txpower;		/**< Minimum possible TX power, dBm */
+	u8 max_txpower;		/**< Maximum possible TX power, dBm */
+} __attribute__ ((packed));
+
+/** Information element ID for Power Capability information element */
+#define IEEE80211_IE_POWER_CAPAB	33
+
+
+/** 802.11 Channels information element channel band tuple */
+struct ieee80211_ie_channels_channel_band {
+	u8 first_channel;	/**< Channel number of first channel in band */
+	u8 nr_channels;		/**< Number of channels in band */
+} __attribute__ ((packed));
+
+/** 802.11 Channels information element
+ *
+ * This is used in association frames to indicate the channels we can
+ * use. It is required only if we indicate support for spectrum
+ * management.
+ */
+struct ieee80211_ie_channels {
+	u8 id;			/**< Channels ID: 36 */
+	u8 len;			/**< Channels length: 2 */
+
+	/** List of (start, length) channel bands we can use */
+	struct ieee80211_ie_channels_channel_band channels[0];
+} __attribute__ ((packed));
+
+/** Information element ID for Channels information element */
+#define IEEE80211_IE_CHANNELS	36
+
+
+/** 802.11 ERP Information information element
+ *
+ * This is used to communicate some PHY-level flags.
+ */
+struct ieee80211_ie_erp_info {
+	u8 id;			/**< ERP Information ID: 42 */
+	u8 len;			/**< ERP Information length: 1 */
+	u8 erp_info;		/**< ERP flags */
+} __attribute__ ((packed));
+
+/** Information element ID for ERP Information information element */
+#define IEEE80211_IE_ERP_INFO	42
+
+/** ERP information element: Flag set if 802.11b stations are present */
+#define  IEEE80211_ERP_NONERP_PRESENT	0x01
+
+/** ERP information element: Flag set if CTS protection must be used */
+#define  IEEE80211_ERP_USE_PROTECTION	0x02
+
+/** ERP information element: Flag set if long preambles must be used */
+#define  IEEE80211_ERP_BARKER_LONG	0x04
+
+
+/** 802.11 Robust Security Network ("WPA") information element
+ *
+ * Showing once again a striking clarity of design, the IEEE folks put
+ * dynamically-sized data in the middle of this structure. As such,
+ * the below structure definition is only a guideline; the
+ * @c IEEE80211_RSN_FIELD, @c IEEE80211_RSN_CIPHER, and
+ * @c IEEE80211_RSN_AUTHTYPE macros should be used to access any
+ * data.
+ *
+ * Also inspired was IEEE's choice of 16-bit fields to count the
+ * number of 4-byte elements in a structure with a maximum length of
+ * 255 bytes.
+ *
+ * Many fields reference a cipher or authentication-type ID; this is a
+ * three-byte OUI followed by one byte identifying the cipher with
+ * respect to that OUI. For all standard ciphers the OUI is 00:0F:AC.
+ *
+ * The authentication types referenced in this structure have nothing
+ * to do with 802.11 authentication frames or the @c algorithm field
+ * within them.
+ */
+struct ieee80211_ie_rsn {
+	/** Information element ID */
+	u8 id;
+
+	/** Information element length */
+	u8 len;
+
+	/** RSN information element version */
+	u16 version;
+
+	/** Cipher ID for the cipher used in multicast/broadcast frames */
+	u8 group_cipher[4];
+
+	/** Number of unicast ciphers supported */
+	u16 pairwise_count;
+
+	/** List of cipher IDs for supported unicast frame ciphers */
+	u8 pairwise_cipher[4];
+
+	/** Number of authentication types supported */
+	u16 akm_count;
+
+	/** List of authentication type IDs for supported types */
+	u8 akm_list[4];
+
+	/** Security capabilities field. */
+	u16 rsn_capab;
+
+	/** Number of PMKIDs included (present only in association frames) */
+	u16 pmkid_count;
+
+	/** List of PMKIDs included, each a 16-byte SHA1 hash */
+	u8 pmkid_list[0];
+} __attribute__((packed));
+
+/** Information element ID for Robust Security Network information element */
+#define IEEE80211_IE_RSN	48
+
+/** OUI for standard ciphers in RSN information element */
+#define  IEEE80211_RSN_OUI	"\x00\x0F\xAC"
+
+/** Extract RSN IE version field */
+#define  IEEE80211_RSN_FIELD_version( rsnp ) ( (rsnp)->version )
+
+/** Extract RSN IE group_cipher field */
+#define  IEEE80211_RSN_FIELD_group_cipher( rsnp ) ( (rsnp)->group_cipher )
+
+/** Extract RSN IE pairwise_count field */
+#define  IEEE80211_RSN_FIELD_pairwise_count( rsnp ) ( (rsnp)->pairwise_count )
+
+/** Extract RSN IE akm_count field */
+#define  IEEE80211_RSN_FIELD_akm_count( rsnp )			\
+	( ( ( struct ieee80211_ie_rsn * ) ( ( void * ) ( rsnp ) + \
+		4*( ( rsnp )->pairwise_count - 1 ) ) )->akm_count )
+
+/** Extract RSN IE rsn_capab field */
+#define  IEEE80211_RSN_FIELD_rsn_capab( rsnp )			\
+	( ( ( struct ieee80211_ie_rsn * ) ( ( void * ) ( rsnp ) + \
+		4*( ( rsnp )->pairwise_count - 1 ) +		\
+		4*( ( rsnp )->akm_count - 1 ) ) )->rsn_capab )
+
+/** Extract RSN IE pmkid_count field */
+#define  IEEE80211_RSN_FIELD_pmkid_count( rsnp )		\
+	( ( ( struct ieee80211_ie_rsn * ) ( ( void * ) ( rsnp ) + \
+		4*( ( rsnp )->pairwise_count - 1 ) +		\
+		4*( ( rsnp )->akm_count - 1 ) ) )->pmkid_count )
+
+/** Extract field from RSN information element
+ *
+ * @v rsnp	Pointer to RSN information element
+ * @v field	Name of field to extract
+ * @ret val	Lvalue of the requested field
+ *
+ * You must fill the fields of the structure in order for this to work
+ * properly.
+ */
+#define  IEEE80211_RSN_FIELD( rsnp, field )	\
+	IEEE80211_RSN_FIELD_ ## field ( rsnp )
+
+/** Get pointer to pairwise cipher from RSN information element
+ *
+ * @v rsnp	Pointer to RSN information element
+ * @v cipher	Index of pairwise cipher to extract
+ * @ret ptr	Pointer to requested cipher
+ */
+#define  IEEE80211_RSN_CIPHER( rsnp, cipher )	\
+	( ( rsnp )->pairwise_cipher + 4 * ( cipher ) )
+
+/** Get pointer to authentication type from RSN information element
+ *
+ * @v rsnp	Pointer to RSN information element
+ * @v akm	Index of authentication type to extract
+ * @ret ptr	Pointer to requested authentication type
+ *
+ * The @c pairwise_count field must be correct.
+ */
+#define  IEEE80211_RSN_AUTHTYPE( rsnp, akm )	\
+    ( ( rsnp )->akm_list + 4 * ( ( rsnp )->pairwise_count - 1 ) + 4 * ( akm ) )
+
+/** Get pointer to PMKID from RSN information element
+ *
+ * @v rsnp	Pointer to RSN information element
+ * @v idx	Index of PMKID to extract
+ * @ret ptr	Pointer to requested PMKID
+ *
+ * The @c pairwise_count and @c akm_count fields must be correct.
+ */
+#define  IEEE80211_RSN_PMKID( rsnp, idx )	\
+	( ( rsnp )->pmkid_list + 4 * ( ( rsnp )->pairwise_count - 1 ) +	\
+			4 * ( ( rsnp )->akm_count - 1 ) + 16 * ( idx ) )
+
+/** Verify size of RSN information element
+ *
+ * @v rsnp	Pointer to RSN information element
+ * @ret ok	TRUE if count fields are consistent with length field
+ *
+ * It is important to drop any RSN IE that does not pass this function
+ * before using the @c IEEE80211_RSN_FIELD, @c IEEE80211_RSN_CIPHER,
+ * and @c IEEE80211_RSN_AUTHTYPE macros, to avoid potential security
+ * compromise due to a malformed RSN IE.
+ *
+ * This function does not consider the possibility of some PMKIDs
+ * included in the RSN IE, because PMKIDs are only included in RSN IEs
+ * sent in association request frames, and we should never receive an
+ * association request frame. An RSN IE that includes PMKIDs will
+ * always fail this check.
+ */
+static inline int ieee80211_rsn_check ( struct ieee80211_ie_rsn *rsnp ) {
+	if ( rsnp->len < 12 + 4 * rsnp->pairwise_count )
+		return 0;
+	return ( rsnp->len == 12 + 4 * ( rsnp->pairwise_count +
+				IEEE80211_RSN_FIELD ( rsnp, akm_count ) ) );
+}
+
+/** Calculate necessary size of RSN information element
+ *
+ * @v npair	Number of pairwise ciphers supported
+ * @v nauth	Number of authentication types supported
+ * @v npmkid	Number of PMKIDs to include
+ * @ret size	Necessary size of RSN IE, including header bytes
+ */
+static inline size_t ieee80211_rsn_size ( int npair, int nauth, int npmkid ) {
+	return 16 + 4 * ( npair + nauth ) + 16 * npmkid;
+}
+
+/** 802.11 RSN IE: expected version number */
+#define  IEEE80211_RSN_VERSION		1
+
+/** 802.11 RSN IE: fourth byte of cipher type for 40-bit WEP */
+#define  IEEE80211_RSN_CTYPE_WEP40	1
+
+/** 802.11 RSN IE: fourth byte of cipher type for 104-bit WEP */
+#define  IEEE80211_RSN_CTYPE_WEP104	5
+
+/** 802.11 RSN IE: fourth byte of cipher type for TKIP ("WPA") */
+#define  IEEE80211_RSN_CTYPE_TKIP	2
+
+/** 802.11 RSN IE: fourth byte of cipher type for CCMP ("WPA2") */
+#define  IEEE80211_RSN_CTYPE_CCMP	4
+
+/** 802.11 RSN IE: fourth byte of cipher type for "use group"
+ *
+ * This can only appear as a pairwise cipher, and means unicast frames
+ * should be encrypted in the same way as broadcast/multicast frames.
+ */
+#define  IEEE80211_RSN_CTYPE_USEGROUP	0
+
+/** 802.11 RSN IE: fourth byte of auth method type for using an 802.1X server */
+#define  IEEE80211_RSN_ATYPE_8021X	1
+
+/** 802.11 RSN IE: fourth byte of auth method type for using a pre-shared key */
+#define  IEEE80211_RSN_ATYPE_PSK	2
+
+/** 802.11 RSN IE capabilities: AP supports pre-authentication */
+#define  IEEE80211_RSN_CAPAB_PREAUTH	0x001
+
+/** 802.11 RSN IE capabilities: Node has conflict between TKIP and WEP
+ *
+ * This is a legacy issue; APs always set it to 0, and gPXE sets it to
+ * 0.
+ */
+#define  IEEE80211_RSN_CAPAB_NO_PAIRWISE 0x002
+
+/** 802.11 RSN IE capabilities: Number of PTKSA replay counters
+ *
+ * A value of 0 means one replay counter, 1 means two, 2 means four,
+ * and 3 means sixteen.
+ */
+#define  IEEE80211_RSN_CAPAB_PTKSA_REPLAY 0x00C
+
+/** 802.11 RSN IE capabilities: Number of GTKSA replay counters
+ *
+ * A value of 0 means one replay counter, 1 means two, 2 means four,
+ * and 3 means sixteen.
+ */
+#define  IEEE80211_RSN_CAPAB_GTKSA_REPLAY 0x030
+
+/** 802.11 RSN IE capabilities: PeerKey Handshaking is suported */
+#define  IEEE80211_RSN_CAPAB_PEERKEY	0x200
+
+
+
+/** Any 802.11 information element
+ *
+ * This is formatted for ease of use, so IEs with complex structures
+ * get referenced in full, while those with only one byte of data or a
+ * simple array are pulled in to avoid a layer of indirection like
+ * ie->channels.channels[0].
+ */
+union ieee80211_ie
+{
+	/** Generic and simple information element info */
+	struct {
+		u8 id;		/**< Information element ID */
+		u8 len;		/**< Information element data length */
+		union {
+			char ssid[0];	/**< SSID text */
+			u8 rates[0];	/**< Rates data */
+			u8 request[0];	/**< Request list */
+			u8 challenge_text[0]; /**< Challenge text data */
+			u8 power_constraint; /**< Power constraint, dBm */
+			u8 erp_info;	/**< ERP information flags */
+			/** List of channels */
+			struct ieee80211_ie_channels_channel_band channels[0];
+		};
+	};
+
+	/** DS parameter set */
+	struct ieee80211_ie_ds_param ds_param;
+
+	/** Country information */
+	struct ieee80211_ie_country country;
+
+	/** Power capability */
+	struct ieee80211_ie_power_capab power_capab;
+
+	/** Security information */
+	struct ieee80211_ie_rsn rsn;
+};
+
+/** Advance to next 802.11 information element
+ *
+ * @v ie	Current information element pointer
+ * @v end	Pointer to first byte not in information element space
+ * @ret next	Pointer to next information element, or NULL if no more
+ *
+ * When processing received IEs, @a end should be set to the I/O
+ * buffer tail pointer; when marshalling IEs for sending, @a end
+ * should be NULL.
+ */
+static inline union ieee80211_ie * ieee80211_next_ie ( union ieee80211_ie *ie,
+						       void *end )
+{
+	void *next_ie_byte = ( void * ) ie + ie->len + 2;
+	union ieee80211_ie *next_ie = next_ie_byte;
+
+	if ( ! end )
+		return next_ie;
+
+	if ( next_ie_byte < end && next_ie_byte + next_ie->len <= end )
+		return next_ie;
+
+	return NULL;
+}
+
+/** @} */
+
+
+/* ---------- Management frame data formats ---------- */
+
+/**
+ * @defgroup ieee80211_mgmt_data Management frame data payloads
+ * @{
+ */
+
+/** Beacon or probe response frame data */
+struct ieee80211_beacon_or_probe_resp
+{
+	/** 802.11 TSFT value at frame send */
+	u64 timestamp;
+
+	/** Interval at which beacons are sent, in units of 1024 us */
+	u16 beacon_interval;
+
+	/** Capability flags */
+	u16 capability;
+
+	/** List of information elements */
+	union ieee80211_ie info_element[0];
+} __attribute__((packed));
+
+#define ieee80211_beacon	ieee80211_beacon_or_probe_resp
+#define ieee80211_probe_resp	ieee80211_beacon_or_probe_resp
+
+/** Disassociation or deauthentication frame data */
+struct ieee80211_disassoc_or_deauth
+{
+	/** Reason code */
+	u16 reason;
+} __attribute__((packed));
+
+#define ieee80211_disassoc	ieee80211_disassoc_or_deauth
+#define ieee80211_deauth	ieee80211_disassoc_or_deauth
+
+/** Association request frame data */
+struct ieee80211_assoc_req
+{
+	/** Capability flags */
+	u16 capability;
+
+	/** Interval at which we wake up, in units of the beacon interval */
+	u16 listen_interval;
+
+	/** List of information elements */
+	union ieee80211_ie info_element[0];
+} __attribute__((packed));
+
+/** Association or reassociation response frame data */
+struct ieee80211_assoc_or_reassoc_resp
+{
+	/** Capability flags */
+	u16 capability;
+
+	/** Status code */
+	u16 status;
+
+	/** Association ID */
+	u16 aid;
+
+	/** List of information elements */
+	union ieee80211_ie info_element[0];
+} __attribute__((packed));
+
+#define ieee80211_assoc_resp	ieee80211_assoc_or_reassoc_resp
+#define ieee80211_reassoc_resp	ieee80211_assoc_or_reassoc_resp
+
+/** Reassociation request frame data */
+struct ieee80211_reassoc_req
+{
+	/** Capability flags */
+	u16 capability;
+
+	/** Interval at which we wake up, in units of the beacon interval */
+	u16 listen_interval;
+
+	/** MAC address of current Access Point */
+	u8 current_addr[ETH_ALEN];
+
+	/** List of information elements */
+	union ieee80211_ie info_element[0];
+} __attribute__((packed));
+
+/** Probe request frame data */
+struct ieee80211_probe_req
+{
+	/** List of information elements */
+	union ieee80211_ie info_element[0];
+} __attribute__((packed));
+
+/** Authentication frame data */
+struct ieee80211_auth
+{
+	/** Authentication algorithm (Open System or Shared Key) */
+	u16 algorithm;
+
+	/** Sequence number of this frame; first from client to AP is 1 */
+	u16 tx_seq;
+
+	/** Status code */
+	u16 status;
+
+	/** List of information elements */
+	union ieee80211_ie info_element[0];
+} __attribute__((packed));
+
+/** Open System authentication algorithm */
+#define IEEE80211_AUTH_OPEN_SYSTEM  0
+
+/** Shared Key authentication algorithm */
+#define IEEE80211_AUTH_SHARED_KEY   1
+
+/** @} */
+
+#endif