Advertisement parsing fix for zero padding am: 819b843f53 (a73be388) · Commits · e / os / android_packages_modules_Bluetooth

system/stack/btm/btm_ble_gap.cc

+5 −2

Original line number	Diff line number	Diff line
		@@ -2017,11 +2017,14 @@ static void btm_ble_process_adv_pkt_cont(
		bool is_scannable = ble_evt_type_is_scannable(evt_type);
		bool is_scan_resp = ble_evt_type_is_scan_resp(evt_type);

		bool is_start =
		ble_evt_type_is_legacy(evt_type) && is_scannable && !is_scan_resp;

		if (is_start) AdvertiseDataParser::RemoveTrailingZeros(tmp);

		// We might have send scan request to this device before, but didn't get the
		// response. In such case make sure data is put at start, not appended to
		// already existing data.
		bool is_start =
		ble_evt_type_is_legacy(evt_type) && is_scannable && !is_scan_resp;
		std::vector<uint8_t> const& adv_data =
		is_start ? cache.Set(addr_type, bda, std::move(tmp))
		: cache.Append(addr_type, bda, std::move(tmp));

+30 −0

Original line number	Diff line number	Diff line
		@@ -44,6 +44,36 @@ class AdvertiseDataParser {
		}

		public:
		static void RemoveTrailingZeros(std::vector<uint8_t>& ad) {
		size_t position = 0;

		size_t ad_len = ad.size();
		while (position != ad_len) {
		uint8_t len = ad[position];

		// A field length of 0 would be invalid as it should at least contain the
		// EIR field type. However, some existing devices send zero padding at the
		// end of advertisement. If this is the case, cut the zero padding from
		// end of the packet. Otherwise i.e. gluing scan response to advertise
		// data will result in data with zero padding in the middle.
		if (len == 0) {
		size_t zeros_start = position;
		for (size_t i = position + 1; i < ad_len; i++) {
		if (ad[i] != 0) return;
		}

		ad.erase(ad.begin() + zeros_start, ad.end());
		return;
		}

		if (position + len >= ad_len) {
		return;
		}

		position += len + 1;
		}
		}

		/**
		* Return true if this \|ad\| represent properly formatted advertising data.
		*/

+21 −0

Original line number	Diff line number	Diff line
		@@ -128,3 +128,24 @@ TEST(AdvertiseDataParserTest, GetFieldByType) {
		EXPECT_EQ(nullptr, data);
		EXPECT_EQ(0, p_length);
		}

		// This test makes sure that RemoveTrailingZeros is working correctly. It does
		// run the RemoveTrailingZeros for ad data, then glue scan response at end of
		// it, and checks that the resulting data is good.
		TEST(AdvertiseDataParserTest, RemoveTrailingZeros) {
		std::vector<uint8_t> podo_ad_data{
		0x02, 0x01, 0x02, 0x11, 0x06, 0x66, 0x9a, 0x0c, 0x20, 0x00, 0x08,
		0x37, 0xa8, 0xe5, 0x11, 0x81, 0x8b, 0xd0, 0xf0, 0xf0, 0xf0, 0x00,
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00};
		const std::vector<uint8_t> podo_scan_resp{
		0x03, 0x19, 0x00, 0x80, 0x09, 0x09, 0x50, 0x6f, 0x64, 0x6f, 0x51,
		0x35, 0x56, 0x47, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00};

		AdvertiseDataParser::RemoveTrailingZeros(podo_ad_data);

		std::vector<uint8_t> glued(podo_ad_data);
		glued.insert(glued.end(), podo_ad_data.begin(), podo_ad_data.end());

		EXPECT_TRUE(AdvertiseDataParser::IsValid(glued));
		}
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