ieee80211_has_a4(9)

💖 ieee80211_has_a4(9) 💖

okay so this is a page from the Kernel API Manual, and bestie, it's a tiny little function with a very long friend list. let's get into it ✨

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🌸 NAME 🌸

ieee80211_has_a4 — check if IEEE80211_FCTL_TODS and IEEE80211_FCTL_FROMDS are set

like, that's the whole job. it peeks at two bits and tells you what's up. icon behavior, honestly.

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🦋 SYNOPSIS 🦋

bool ieee80211_has_a4 (__le16 fc );

yep. one argument. returns a bool. no drama, no cap 💅

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🎀 ARGUMENTS 🎀

• fc — the frame control bytes, in little-endian byteorder. the way that endianness matters here… don't @ me, just pass it correctly fr fr 🙈

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⭐ RETURN ⭐

it tells you whether or not it's a 4-address frame — which happens when from-DS and to-DS are both set. that's the vibe check: two bits on, four addresses, main character energy 👑

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🌈 SEE ALSO 🌈

okay this is the part where the page just dumps its entire contact list on you and honestly? respect. the kernel file is ./include/linux/ieee80211.h, and here is literally everyone:

• ieee80211_has_tods(9), ieee80211_has_fromds(9), ieee80211_has_morefrags(9), ieee80211_has_retry(9), ieee80211_has_pm(9), ieee80211_has_moredata(9), ieee80211_has_protected(9), ieee80211_has_order(9)
• ieee80211_is_mgmt(9), ieee80211_is_ctl(9), ieee80211_is_data(9), ieee80211_is_ext(9), ieee80211_is_data_qos(9), ieee80211_is_data_present(9)
• ieee80211_is_assoc_req(9), ieee80211_is_assoc_resp(9), ieee80211_is_reassoc_req(9), ieee80211_is_reassoc_resp(9), ieee80211_is_assoc(9)
• ieee80211_is_probe_req(9), ieee80211_is_probe_resp(9), ieee80211_is_beacon(9), ieee80211_is_atim(9), ieee80211_is_disassoc(9)
• ieee80211_is_auth(9), ieee80211_is_deauth(9), ieee80211_is_action(9), ieee80211_is_back_req(9), ieee80211_is_back(9), ieee80211_is_pspoll(9)
• ieee80211_is_rts(9), ieee80211_is_cts(9), ieee80211_is_ack(9), ieee80211_is_cfend(9), ieee80211_is_cfendack(9)
• ieee80211_is_nullfunc(9), ieee80211_is_qos_nullfunc(9), ieee80211_is_trigger(9), ieee80211_is_any_nullfunc(9)
• ieee80211_is_first_frag(9), ieee80211_is_frag(9)
• struct ieee80211_quiet_ie(9), struct ieee80211_msrment_ie(9), struct ieee80211_channel_sw_ie(9), struct ieee80211_ext_chansw_ie(9), struct ieee80211_sec_chan_offs_ie(9), struct ieee80211_wide_bw_chansw_ie(9)
• struct ieee80211_tim_ie(9), struct ieee80211_tpc_report_ie(9), struct ieee80211_bss_load_elem(9), struct ieee80211_timeout_interval_ie(9)
• enum ieee80211_idle_options(9), struct ieee80211_bss_max_idle_period_ie(9), struct ieee80211_bssid_index(9), struct ieee80211_multiple_bssid_configuration(9)
• ieee80211_get_qos_ctl(9), ieee80211_get_tid(9), ieee80211_get_SA(9), ieee80211_get_DA(9)
• ieee80211_is_bufferable_mmpdu(9), _ieee80211_is_robust_mgmt_frame(9), ieee80211_is_robust_mgmt_frame(9), ieee80211_is_public_action(9), ieee80211_is_protected_dual_of_public_action(9)
• _ieee80211_is_group_privacy_action(9), ieee80211_is_group_privacy_action(9)
• ieee80211_tu_to_usec(9), ieee80211_get_tdls_action(9), ieee80211_action_contains_tpc(9), ieee80211_is_timing_measurement(9), ieee80211_is_ftm(9)
• for_each_element_completed(9), struct ieee80211_enh_crit_upd(9), ieee80211_check_tim(9)

ngl that list is a lot, but every single one of them is a real one, so go read them if you're curious 🫶

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and that's the whole page, bestie! 💜 this one lives in ./include/linux, it's dated October 2026, and yes — it signs off as ieee80211_has_a4(9), always and forever 🎀✨💅