[PATCH v3 3/6] anqp: refactor to use frame-xchg

[James Prestwood <prestwoj@gmail.com>]

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The new frame-xchg module now handles a lot of what ANQP used to do. ANQP
now does not need to depend on nl80211/netdev for building and sending
frames. It also no longer needs any of the request lookups, frame watches
or to maintain a queue of requests because frame-xchg filters this for us.

From an API perspective:
 - anqp_request() was changed to take the wdev_id rather than ifindex.
 - anqp_cancel() was added so that station can properly clean up ANQP
   requests if the device disappears.

During testing a bug was also fixed in station on the timeout path
where the request queue would get popped twice.
---
 src/anqp.c    | 443 +++++++++++---------------------------------------
 src/anqp.h    |   3 +-
 src/station.c |  19 +--
 3 files changed, 103 insertions(+), 362 deletions(-)

diff --git a/src/anqp.c b/src/anqp.c
index 6627bd81..3b597835 100644
--- a/src/anqp.c
+++ b/src/anqp.c
@@ -31,105 +31,61 @@
 #include "src/module.h"
 #include "src/anqp.h"
 #include "src/util.h"
-#include "src/eap-private.h"
 #include "src/ie.h"
-#include "src/nl80211util.h"
-#include "src/nl80211cmd.h"
 #include "src/scan.h"
-#include "src/netdev.h"
 #include "src/iwd.h"
 #include "src/mpdu.h"
-#include "src/wiphy.h"
+#include "src/frame-xchg.h"
 
 #include "linux/nl80211.h"
 
+#define ANQP_GROUP	0
+
 struct anqp_request {
-	uint32_t ifindex;
+	uint64_t wdev_id;
 	anqp_response_func_t anqp_cb;
 	anqp_destroy_func_t anqp_destroy;
 	void *anqp_data;
-	uint64_t anqp_cookie;
 	uint8_t anqp_token;
+	uint32_t frequency;
+	uint8_t *frame;
+	size_t frame_len;
+	uint32_t id;
 };
 
-static struct l_genl_family *nl80211 = NULL;
-
-static struct l_queue *anqp_requests;
 static uint8_t anqp_token = 0;
 
-static uint32_t netdev_watch;
-static uint32_t unicast_watch;
-
 static void anqp_destroy(void *user_data)
 {
 	struct anqp_request *request = user_data;
 
 	if (request->anqp_destroy)
 		request->anqp_destroy(request->anqp_data);
-}
-
-static void netdev_gas_request_cb(struct l_genl_msg *msg, void *user_data)
-{
-	struct anqp_request *request = user_data;
-
-	if (l_genl_msg_get_error(msg) != 0)
-		goto error;
-
-	if (nl80211_parse_attrs(msg, NL80211_ATTR_COOKIE, &request->anqp_cookie,
-					NL80211_ATTR_UNSPEC) < 0)
-		goto error;
-
-	return;
-
-error:
-	l_debug("Error sending CMD_FRAME (%d)", l_genl_msg_get_error(msg));
-
-	if (request->anqp_cb)
-		request->anqp_cb(ANQP_FAILED, NULL, 0, request->anqp_data);
-
-	if (request->anqp_destroy)
-		request->anqp_destroy(request->anqp_data);
 
+	l_free(request->frame);
 	l_free(request);
 }
 
-static bool match_token(const void *a, const void *b)
-{
-	const struct anqp_request *request = a;
-	const struct token_match {
-		uint32_t ifindex;
-		uint8_t token;
-
-	} *match = b;
-
-	if (request->ifindex != match->ifindex)
-		return false;
-
-	if (request->anqp_token != match->token)
-		return false;
-
-	return true;
-}
-
-static void anqp_response_frame_event(uint32_t ifindex,
-					const struct mmpdu_header *hdr,
-					const void *body, size_t body_len)
+/*
+ * By using frame-xchg we should get called back here for any frame matching our
+ * prefix until the duration expires. If frame-xchg is never signalled 'done'
+ * (returning true) we should get a timeout in anqp_frame_timeout. This is
+ * why we drop any improperly formatted frames without cleaning up the request.
+ */
+static bool anqp_response_frame_event(const struct mmpdu_header *hdr,
+					const void *body, size_t body_len,
+					int rssi, void *user_data)
 {
-	struct anqp_request *request;
+	struct anqp_request *request = user_data;
 	const uint8_t *ptr = body;
 	uint16_t status_code;
 	uint16_t delay;
 	uint16_t qrlen;
 	uint8_t adv_proto_len;
 	uint8_t token;
-	struct token_match {
-		uint32_t ifindex;
-		uint8_t token;
-
-	} match;
 
 	if (body_len < 9)
-		return;
+		return false;
 
 	/* Skip past category/action since this frame was prefixed matched */
 	ptr += 2;
@@ -138,12 +94,8 @@ static void anqp_response_frame_event(uint32_t ifindex,
 	/* dialog token */
 	token = *ptr++;
 
-	match.ifindex = ifindex;
-	match.token = token;
-
-	request = l_queue_find(anqp_requests, match_token, &match);
-	if (!request)
-		return;
+	if (request->anqp_token != token)
+		return false;
 
 	status_code = l_get_le16(ptr);
 	ptr += 2;
@@ -151,7 +103,7 @@ static void anqp_response_frame_event(uint32_t ifindex,
 
 	if (status_code != 0) {
 		l_error("Bad status code on GAS response %u", status_code);
-		return;
+		return false;
 	}
 
 	delay = l_get_le16(ptr);
@@ -166,12 +118,12 @@ static void anqp_response_frame_event(uint32_t ifindex,
 	 */
 	if (delay != 0) {
 		l_error("GAS comeback delay was not zero");
-		return;
+		return false;
 	}
 
 	if (*ptr != IE_TYPE_ADVERTISEMENT_PROTOCOL) {
 		l_error("GAS request not advertisement protocol");
-		return;
+		return false;
 	}
 
 	ptr++;
@@ -181,339 +133,128 @@ static void anqp_response_frame_event(uint32_t ifindex,
 	body_len--;
 
 	if (body_len < adv_proto_len)
-		return;
+		return false;
 
 	ptr += adv_proto_len;
 	body_len -= adv_proto_len;
 
 	if (body_len < 2)
-		return;
+		return false;
 
 	qrlen = l_get_le16(ptr);
 	ptr += 2;
 
 	if (body_len < qrlen)
-		return;
-
-	l_queue_remove(anqp_requests, request);
+		return false;
 
 	l_debug("ANQP response received from "MAC, MAC_STR(hdr->address_2));
 
 	if (request->anqp_cb)
-		request->anqp_cb(ANQP_SUCCESS, ptr, qrlen,
-					request->anqp_data);
-
-	if (request->anqp_destroy)
-		request->anqp_destroy(request->anqp_data);
+		request->anqp_cb(ANQP_SUCCESS, ptr, qrlen, request->anqp_data);
 
-	l_free(request);
+	anqp_destroy(request);
 
-	return;
+	return true;
 }
 
-static void netdev_gas_timeout_cb(void *user_data)
+static const struct frame_xchg_prefix anqp_frame_prefix = {
+	.data = (uint8_t []) {
+		0x04, 0x0b,
+	},
+	.len = 2,
+};
+
+static void anqp_frame_timeout(int error, void *user_data)
 {
 	struct anqp_request *request = user_data;
+	enum anqp_result result = ANQP_TIMEOUT;
 
-	l_debug("GAS request timed out");
+	if (error < 0) {
+		result = ANQP_FAILED;
+		l_error("Sending ANQP request failed: %s (%i)",
+			strerror(-error), -error);
+	}
 
 	if (request->anqp_cb)
-		request->anqp_cb(ANQP_TIMEOUT, NULL, 0,
-					request->anqp_data);
+		request->anqp_cb(result, NULL, 0, request->anqp_data);
 
-	/* allows anqp_request to be re-entrant */
 	if (request->anqp_destroy)
 		request->anqp_destroy(request->anqp_data);
 
-	l_queue_remove(anqp_requests, request);
-	l_free(request);
+	anqp_destroy(request);
 }
 
-static bool match_cookie(const void *a, const void *b)
+static uint8_t *anqp_build_frame(const uint8_t *addr, struct scan_bss *bss,
+					const uint8_t *anqp, size_t len,
+					size_t *len_out)
 {
-	const struct anqp_request *request = a;
-	const struct cookie_match {
-		uint64_t cookie;
-		uint32_t ifindex;
-	} *match = b;
+	uint8_t *frame = l_malloc(len + 33);
+	uint8_t *ptr;
 
-	if (match->ifindex != request->ifindex)
-		return false;
+	memset(frame, 0, len + 33);
 
-	if (match->cookie != request->anqp_cookie)
-		return false;
+	l_put_le16(0x00d0, frame + 0);
+	memcpy(frame + 4, bss->addr, 6);
+	memcpy(frame + 10, addr, 6);
+	memcpy(frame + 16, bss->addr, 6);
 
-	return true;
-}
+	ptr = frame + 24;
 
-static void anqp_frame_wait_cancel_event(struct l_genl_msg *msg,
-						uint32_t ifindex)
-{
-	uint64_t cookie;
-	struct anqp_request *request;
-	struct cookie_match {
-		uint64_t cookie;
-		uint32_t ifindex;
-	} match;
+	*ptr++ = 0x04;			/* Category: Public */
+	*ptr++ = 0x0a;			/* Action: GAS initial Request */
+	*ptr++ = anqp_token++;		/* Dialog Token */
+	*ptr++ = IE_TYPE_ADVERTISEMENT_PROTOCOL;
+	*ptr++ = 2;
 
-	l_debug("");
-
-	if (nl80211_parse_attrs(msg, NL80211_ATTR_COOKIE, &cookie,
-					NL80211_ATTR_UNSPEC) < 0)
-		return;
-
-	match.cookie = cookie;
-	match.ifindex = ifindex;
+	*ptr++ = 0x7f;
+	*ptr++ = IE_ADVERTISEMENT_ANQP;
+	l_put_le16(len, ptr);
+	ptr += 2;
 
-	request = l_queue_find(anqp_requests, match_cookie, &match);
-	if (!request)
-		return;
+	memcpy(ptr, anqp, len);
+	ptr += len;
 
-	if (cookie != request->anqp_cookie)
-		return;
+	*len_out = ptr - frame;
 
-	netdev_gas_timeout_cb(request);
+	return frame;
 }
 
-uint32_t anqp_request(uint32_t ifindex, const uint8_t *addr,
-				struct scan_bss *bss, const uint8_t *anqp,
-				size_t len, anqp_response_func_t cb,
-				void *user_data, anqp_destroy_func_t destroy)
+uint32_t anqp_request(uint64_t wdev_id, const uint8_t *addr,
+			struct scan_bss *bss, const uint8_t *anqp,
+			size_t len, anqp_response_func_t cb,
+			void *user_data, anqp_destroy_func_t destroy)
 {
 	struct anqp_request *request;
-	uint8_t frame[512];
-	struct l_genl_msg *msg;
 	struct iovec iov[2];
-	uint32_t id;
-	uint32_t duration = 300;
-	struct netdev *netdev = netdev_find(ifindex);
-
-	if (!netdev)
-		return 0;
-
-	/*
-	 * TODO: Netdev dependencies will eventually be removed so we need
-	 * another way to figure out wiphy capabilities.
-	 */
-	if (!wiphy_can_offchannel_tx(netdev_get_wiphy(netdev))) {
-		l_error("ANQP failed, driver does not support offchannel TX");
-		return 0;
-	}
-
-	frame[0] = 0x04;		/* Category: Public */
-	frame[1] = 0x0a;		/* Action: GAS initial Request */
-	frame[2] = anqp_token;		/* Dialog Token */
-	frame[3] = IE_TYPE_ADVERTISEMENT_PROTOCOL;
-	frame[4] = 2;
-	frame[5] = 0x7f;
-	frame[6] = IE_ADVERTISEMENT_ANQP;
-	l_put_le16(len, frame + 7);
-
-	iov[0].iov_base = frame;
-	iov[0].iov_len = 9;
-	iov[1].iov_base = (void *)anqp;
-	iov[1].iov_len = len;
 
 	request = l_new(struct anqp_request, 1);
 
-	request->ifindex = ifindex;
+	request->wdev_id = wdev_id;
+	request->frequency = bss->frequency;
 	request->anqp_cb = cb;
 	request->anqp_destroy = destroy;
-	request->anqp_token = anqp_token++;
+	request->anqp_token = anqp_token;
 	request->anqp_data = user_data;
 
-	msg = nl80211_build_cmd_frame(ifindex, addr, bss->addr,
-					bss->frequency, iov, 2);
-
-	l_genl_msg_append_attr(msg, NL80211_ATTR_OFFCHANNEL_TX_OK, 0, "");
-	l_genl_msg_append_attr(msg, NL80211_ATTR_DURATION, 4, &duration);
-
-	id = l_genl_family_send(nl80211, msg, netdev_gas_request_cb,
-					request, NULL);
-
-	if (!id) {
-		l_debug("Failed to send ANQP request");
-		l_genl_msg_unref(msg);
-		l_free(request);
-		return 0;
-	}
-
-	l_debug("ANQP request sent to "MAC, MAC_STR(bss->addr));
-
-	l_queue_push_head(anqp_requests, request);
-
-	return id;
-}
-
-static void netdev_frame_cb(struct l_genl_msg *msg, void *user_data)
-{
-	if (l_genl_msg_get_error(msg) < 0)
-		l_error("Could not register frame watch type %04x: %i",
-			L_PTR_TO_UINT(user_data), l_genl_msg_get_error(msg));
-}
-
-static void anqp_register_frame(uint32_t ifindex)
-{
-	struct l_genl_msg *msg;
-	uint16_t frame_type = 0x00d0;
-	uint8_t prefix[] = { 0x04, 0x0b };
-
-	msg = l_genl_msg_new_sized(NL80211_CMD_REGISTER_FRAME, 34);
-
-	l_genl_msg_append_attr(msg, NL80211_ATTR_IFINDEX, 4, &ifindex);
-	l_genl_msg_append_attr(msg, NL80211_ATTR_FRAME_TYPE, 2, &frame_type);
-	l_genl_msg_append_attr(msg, NL80211_ATTR_FRAME_MATCH,
-					sizeof(prefix), prefix);
-
-	l_genl_family_send(nl80211, msg, netdev_frame_cb,
-			L_UINT_TO_PTR(frame_type), NULL);
-}
-
-static void anqp_netdev_watch(struct netdev *netdev,
-				enum netdev_watch_event event, void *user_data)
-{
-	switch (event) {
-	case NETDEV_WATCH_EVENT_NEW:
-		if (netdev_get_iftype(netdev) == NETDEV_IFTYPE_STATION)
-			anqp_register_frame(netdev_get_ifindex(netdev));
-
-		return;
-	default:
-		break;
-	}
-}
-
-static void anqp_unicast_notify(struct l_genl_msg *msg, void *user_data)
-{
-	const struct mmpdu_header *mpdu = NULL;
-	const uint8_t *body;
-	struct l_genl_attr attr;
-	uint16_t type, len;
-	uint16_t frame_len = 0;
-	const void *data;
-	uint8_t cmd;
-	uint32_t ifindex = 0;
-
-	if (l_queue_isempty(anqp_requests))
-		return;
-
-	cmd = l_genl_msg_get_command(msg);
-	if (!cmd)
-		return;
-
-	if (!l_genl_attr_init(&attr, msg))
-		return;
-
-	while (l_genl_attr_next(&attr, &type, &len, &data)) {
-		switch (type) {
-		case NL80211_ATTR_IFINDEX:
-			if (len != sizeof(uint32_t)) {
-				l_warn("Invalid interface index attribute");
-				return;
-			}
-
-			ifindex = *((uint32_t *) data);
-
-			break;
-		case NL80211_ATTR_FRAME:
-			if (mpdu)
-				return;
-
-			mpdu = mpdu_validate(data, len);
-			if (!mpdu)
-				l_error("Frame didn't validate as MMPDU");
-
-			frame_len = len;
-			break;
-		}
-	}
-
-	if (!ifindex || !mpdu)
-		return;
-
-	body = mmpdu_body(mpdu);
-
-	anqp_response_frame_event(ifindex, mpdu, body,
-				(const uint8_t *) mpdu + frame_len - body);
-}
-
-static void anqp_mlme_notify(struct l_genl_msg *msg, void *user_data)
-{
-	struct l_genl_attr attr;
-	uint16_t type, len;
-	const void *data;
-	uint8_t cmd;
-	uint32_t ifindex = 0;
-
-	if (l_queue_isempty(anqp_requests))
-		return;
-
-	cmd = l_genl_msg_get_command(msg);
-
-	l_debug("MLME notification %s(%u)", nl80211cmd_to_string(cmd), cmd);
-
-	if (!l_genl_attr_init(&attr, msg))
-		return;
-
-	while (l_genl_attr_next(&attr, &type, &len, &data)) {
-		switch (type) {
-		case NL80211_ATTR_IFINDEX:
-			if (len != sizeof(uint32_t)) {
-				l_warn("Invalid interface index attribute");
-				return;
-			}
-
-			ifindex = *((uint32_t *) data);
-			break;
-		}
-	}
+	request->frame = anqp_build_frame(addr, bss, anqp, len,
+						&request->frame_len);
 
-	if (!ifindex) {
-		l_warn("MLME notification is missing ifindex attribute");
-		return;
-	}
-
-	switch (cmd) {
-	case NL80211_CMD_FRAME_WAIT_CANCEL:
-		anqp_frame_wait_cancel_event(msg, ifindex);
-		break;
-	}
-}
-
-static int anqp_init(void)
-{
-	struct l_genl *genl = iwd_get_genl();
-
-	nl80211 = l_genl_family_new(genl, NL80211_GENL_NAME);
-
-	anqp_requests = l_queue_new();
+	iov[0].iov_base = request->frame;
+	iov[0].iov_len = request->frame_len;
+	iov[1].iov_base = NULL;
 
-	netdev_watch =  netdev_watch_add(anqp_netdev_watch, NULL, NULL);
+	l_debug("Sending ANQP request");
 
-	unicast_watch = l_genl_add_unicast_watch(genl, NL80211_GENL_NAME,
-						anqp_unicast_notify,
-						NULL, NULL);
+	request->id = frame_xchg_start(request->wdev_id, iov,
+				request->frequency, 0, 300, 0,
+				ANQP_GROUP, anqp_frame_timeout, request, NULL,
+				&anqp_frame_prefix, anqp_response_frame_event,
+				NULL);
 
-	if (!l_genl_family_register(nl80211, "mlme", anqp_mlme_notify,
-								NULL, NULL))
-		l_error("Registering for MLME notification failed");
-
-	return 0;
+	return true;
 }
 
-static void anqp_exit(void)
+void anqp_cancel(uint32_t id)
 {
-	struct l_genl *genl = iwd_get_genl();
-
-	l_genl_family_free(nl80211);
-	nl80211 = NULL;
-
-	l_queue_destroy(anqp_requests, anqp_destroy);
-
-	netdev_watch_remove(netdev_watch);
-
-	l_genl_remove_unicast_watch(genl, unicast_watch);
+	frame_xchg_cancel(id);
 }
-
-IWD_MODULE(anqp, anqp_init, anqp_exit);
-IWD_MODULE_DEPENDS(anqp, netdev);
diff --git a/src/anqp.h b/src/anqp.h
index 998277dd..4d96c9ec 100644
--- a/src/anqp.h
+++ b/src/anqp.h
@@ -34,7 +34,8 @@ typedef void (*anqp_response_func_t)(enum anqp_result result,
 					const void *anqp, size_t len,
 					void *user_data);
 
-uint32_t anqp_request(uint32_t ifindex, const uint8_t *addr,
+uint32_t anqp_request(uint64_t wdev_id, const uint8_t *addr,
 			struct scan_bss *bss, const uint8_t *anqp, size_t len,
 			anqp_response_func_t cb, void *user_data,
 			anqp_destroy_func_t destroy);
+void anqp_cancel(uint32_t id);
diff --git a/src/station.c b/src/station.c
index 3719e0b9..a19195f4 100644
--- a/src/station.c
+++ b/src/station.c
@@ -447,6 +447,9 @@ static void remove_anqp(void *data)
 {
 	struct anqp_entry *entry = data;
 
+	if (entry->pending)
+		anqp_cancel(entry->pending);
+
 	l_free(entry);
 }
 
@@ -476,12 +479,9 @@ static void station_anqp_response_cb(enum anqp_result result,
 	char **realms = NULL;
 	struct nai_search search;
 
-	entry->pending = 0;
-
 	l_debug("");
 
-	if (result == ANQP_TIMEOUT) {
-		l_queue_remove(station->anqp_pending, entry);
+	if (result != ANQP_SUCCESS) {
 		/* TODO: try next BSS */
 		goto request_done;
 	}
@@ -583,11 +583,10 @@ static bool station_start_anqp(struct station *station, struct network *network,
 	 * these are checked in hs20_find_settings_file.
 	 */
 
-	entry->pending = anqp_request(netdev_get_ifindex(station->netdev),
-					netdev_get_address(station->netdev),
-					bss, anqp, ptr - anqp,
-					station_anqp_response_cb,
-					entry, l_free);
+	entry->pending = anqp_request(netdev_get_wdev_id(station->netdev),
+				netdev_get_address(station->netdev), bss, anqp,
+				ptr - anqp, station_anqp_response_cb,
+				entry, NULL);
 	if (!entry->pending) {
 		l_free(entry);
 		return false;
@@ -3252,7 +3251,7 @@ static void station_free(struct station *station)
 
 	watchlist_destroy(&station->state_watches);
 
-	l_queue_destroy(station->anqp_pending, l_free);
+	l_queue_destroy(station->anqp_pending, remove_anqp);
 
 	l_free(station);
 }
-- 
2.21.1