scan: parse Advertisement Protocol Element

This IE tells us what Advertisement Protocols the AP supports. This
is only here to look for ANQP support, so all this does is iterate
through all other Advertisement Protocol tuples looking for ANQP.
If found, anqp_capable is set in the scan_bss

src/scan.c

@@ -745,6 +745,55 @@ static bool scan_parse_vendor_specific(struct scan_bss *bss, const void *data,
 	return false;
 }
 
+/*
+ * Fully parses the Advertisement Protocol Element. The only thing being looked
+ * for is the ANQP protocol ID, but this could be burried behind several other
+ * advertisement tuples so the entire IE may need to be parsed.
+ */
+static bool scan_parse_advertisement_protocol(struct scan_bss *bss,
+						const void *data, uint16_t len)
+{
+	const uint8_t *ptr = data;
+
+	l_debug("");
+
+	while (len) {
+		/*
+		 * TODO: Store query info for GAS response length verification
+		 */
+		uint8_t id = ptr[1];
+
+		switch (id) {
+		/*
+		 * IEEE 802.11-2016 Section 11.25.3.3.1
+		 *
+		 * "A non-AP STA shall not transmit an ANQP request to
+		 * an AP for any ANQP-element unless the ANQP
+		 * Advertisement Protocol ID is included..."
+		 */
+		case IE_ADVERTISEMENT_ANQP:
+			bss->anqp_capable = true;
+			return true;
+		case IE_ADVERTISEMENT_MIH_SERVICE:
+		case IE_ADVERTISEMENT_MIH_DISCOVERY:
+		case IE_ADVERTISEMENT_EAS:
+		case IE_ADVERTISEMENT_RLQP:
+			len -= 2;
+			ptr += 2;
+			break;
+		case IE_ADVERTISEMENT_VENDOR_SPECIFIC:
+			/* IEEE 802.11-2016 Section 9.4.2.26 */
+			len -= ptr[3];
+			ptr += ptr[3];
+			break;
+		default:
+			return false;
+		}
+	}
+
+	return true;
+}
+
 static bool scan_parse_bss_information_elements(struct scan_bss *bss,
 					const void *data, uint16_t len)
 {
@@ -837,6 +886,13 @@ static bool scan_parse_bss_information_elements(struct scan_bss *bss,
 			memcpy(bss->vht_ie, iter.data - 2, iter.len + 2);
 
 			break;
+		case IE_TYPE_ADVERTISEMENT_PROTOCOL:
+			if (iter.len < 2)
+				return false;
+
+			scan_parse_advertisement_protocol(bss, iter.data,
+								iter.len);
+			break;
 		}
 	}
 

src/scan.h

@@ -68,6 +68,7 @@ struct scan_bss {
 	bool has_sup_rates : 1;
 	bool ht_capable : 1;
 	bool vht_capable : 1;
+	bool anqp_capable : 1;
 };
 
 struct scan_parameters {