[PATCH v2 4/9] ft: add FTE/RSNE building to ft_prepare_handshake

[James Prestwood <prestwoj@gmail.com>]

In preparation to remove ft_associate build the FTE/RSNE in
ft_prepare_handshake and set into the handshake object directly.
---
 src/ft.c | 84 ++++++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 82 insertions(+), 2 deletions(-)

diff --git a/src/ft.c b/src/ft.c
index 2cc611b8..358a4594 100644
--- a/src/ft.c
+++ b/src/ft.c
@@ -904,9 +904,15 @@ static void ft_info_destroy(void *data)
 	l_free(info);
 }
 
-static void ft_prepare_handshake(struct ft_info *info,
+static bool ft_prepare_handshake(struct ft_info *info,
 					struct handshake_state *hs)
 {
+	uint32_t kck_len = handshake_state_get_kck_len(hs);
+	struct ie_rsn_info rsn_info;
+	struct ie_ft_info ft_info;
+	uint8_t *fte;
+	uint8_t *rsne;
+
 	handshake_state_set_authenticator_address(hs, info->aa);
 
 	memcpy(hs->mde + 2, info->mde, 3);
@@ -914,7 +920,7 @@ static void ft_prepare_handshake(struct ft_info *info,
 	handshake_state_set_chandef(hs, NULL);
 
 	if (!hs->supplicant_ie)
-		return;
+		return true;
 
 	if (info->authenticator_ie)
 		handshake_state_set_authenticator_ie(hs,
@@ -931,6 +937,80 @@ static void ft_prepare_handshake(struct ft_info *info,
 						info->ft_info.r1khid);
 
 	handshake_state_derive_ptk(hs);
+
+	/*
+	 * Rebuild the RSNE to include the PMKR1Name and append
+	 * MDE + FTE.
+	 *
+	 * 12.8.4: "If present, the RSNE shall be set as follows:
+	 * - Version field shall be set to 1.
+	 * - PMKID Count field shall be set to 1.
+	 * - PMKID field shall contain the PMKR1Name.
+	 * - All other fields shall be as specified in 8.4.2.27
+	 *   and 11.5.3."
+	 */
+	if (ie_parse_rsne_from_data(hs->supplicant_ie,
+					hs->supplicant_ie[1] + 2,
+					&rsn_info) < 0)
+		return false;
+
+	rsn_info.num_pmkids = 1;
+	rsn_info.pmkids = hs->pmk_r1_name;
+	/* Always set OCVC false for FT for now */
+	rsn_info.ocvc = false;
+	rsne = alloca(256);
+
+	ie_build_rsne(&rsn_info, rsne);
+	handshake_state_set_supplicant_ie(hs, rsne);
+
+	/*
+	 * 12.8.4: "If present, the FTE shall be set as follows:
+	 * - ANonce, SNonce, R0KH-ID, and R1KH-ID shall be set to
+	 *   the values contained in the second message of this
+	 *   sequence.
+	 * - The Element Count field of the MIC Control field shall
+	 *   be set to the number of elements protected in this
+	 *   frame (variable).
+	 * [...]
+	 * - All other fields shall be set to 0."
+	 */
+	memset(&ft_info, 0, sizeof(ft_info));
+	ft_info.mic_element_count = 3;
+	memcpy(ft_info.r0khid, hs->r0khid, hs->r0khid_len);
+	ft_info.r0khid_len = hs->r0khid_len;
+	memcpy(ft_info.r1khid, hs->r1khid, 6);
+	ft_info.r1khid_present = true;
+	memcpy(ft_info.anonce, hs->anonce, 32);
+	memcpy(ft_info.snonce, hs->snonce, 32);
+
+	/*
+	 * IEEE 802.11-2020 Section 13.7.1 FT reassociation in an RSN
+	 *
+	 * "If dot11RSNAOperatingChannelValidationActivated is true and
+	 *  the FTO indicates OCVC capability, the target AP shall
+	 *  ensure that OCI subelement of the FTE matches by ensuring
+	 *  that all of the following are true:
+	 *      - OCI subelement is present
+	 *      - Channel information in the OCI matches current
+	 *        operating channel parameters (see 12.2.9)"
+	 */
+	if (hs->supplicant_ocvc && hs->chandef) {
+		oci_from_chandef(hs->chandef, ft_info.oci);
+		ft_info.oci_present = true;
+	}
+
+	fte = alloca(256);
+	ie_build_fast_bss_transition(&ft_info, kck_len, fte);
+
+	if (!ft_calculate_fte_mic(hs, 5, rsne, fte, NULL, ft_info.mic))
+		return false;
+
+	/* Rebuild the FT IE now with the MIC included */
+	ie_build_fast_bss_transition(&ft_info, kck_len, fte);
+
+	handshake_state_set_fte(hs, fte);
+
+	return true;
 }
 
 static bool ft_send_action(struct wiphy_radio_work_item *work)
-- 
2.34.1