Fix ble_scan_parser endianness when parsing UUIDs

In Bluetooth, the UUIDs are given in little endian order. Therefore,
the byte array must be reversed before it is encoded into strings.

Bug: None
Change-Id: I0aeca5a1159566b674638ce3451a33665a5382ca
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2561960Reviewed-by: Sonny Sasaka <sonnysasaka@chromium.org>
Reviewed-by: Ken Rockot <rockot@google.com>
Commit-Queue: Archie Pusaka <apusaka@chromium.org>
Cr-Commit-Position: refs/heads/master@{#834576}

services/data_decoder/ble_scan_parser_impl.cc

@@ -141,7 +141,8 @@ std::string BleScanParserImpl::ParseUuid(base::span<const uint8_t> bytes,
     return std::string();
   }
 
-  std::string uuid = base::HexEncode(bytes.data(), bytes.size());
+  std::vector<uint8_t> reversed(bytes.rbegin(), bytes.rend());
+  std::string uuid = base::HexEncode(reversed.data(), reversed.size());
 
   switch (format) {
     case UuidFormat::kFormat16Bit:

services/data_decoder/ble_scan_parser_impl_unittest.cc

@@ -22,7 +22,7 @@ TEST(BleScanParserImplTest, ParseBadUuidLengthReturnsEmptyString) {
 
 TEST(BleScanParserImplTest, Parse16BitUuid) {
   const uint8_t kUuid16[] = {0xab, 0xcd};
-  const char kExpected[] = "0000ABCD-0000-1000-8000-00805F9B34FB";
+  const char kExpected[] = "0000CDAB-0000-1000-8000-00805F9B34FB";
   std::string actual =
       BleScanParserImpl::ParseUuid(kUuid16, UuidFormat::kFormat16Bit);
   EXPECT_STREQ(kExpected, actual.c_str());
@@ -30,7 +30,7 @@ TEST(BleScanParserImplTest, Parse16BitUuid) {
 
 TEST(BleScanParserImplTest, Parse32BitUuid) {
   const uint8_t kUuid32[] = {0xab, 0xcd, 0xef, 0x01};
-  const char kExpected[] = "ABCDEF01-0000-1000-8000-00805F9B34FB";
+  const char kExpected[] = "01EFCDAB-0000-1000-8000-00805F9B34FB";
   std::string actual =
       BleScanParserImpl::ParseUuid(kUuid32, UuidFormat::kFormat32Bit);
   EXPECT_STREQ(kExpected, actual.c_str());
@@ -39,7 +39,7 @@ TEST(BleScanParserImplTest, Parse32BitUuid) {
 TEST(BleScanParserImplTest, Parse128BitUuid) {
   const uint8_t kUuid128[] = {0xab, 0xcd, 0xef, 0x01, 0x23, 0x45, 0x67, 0x89,
                               0xab, 0xcd, 0xef, 0x01, 0x23, 0x45, 0x67, 0x89};
-  const char kExpected[] = "ABCDEF01-2345-6789-ABCD-EF0123456789";
+  const char kExpected[] = "89674523-01EF-CDAB-8967-452301EFCDAB";
   std::string actual =
       BleScanParserImpl::ParseUuid(kUuid128, UuidFormat::kFormat128Bit);
   EXPECT_STREQ(kExpected, actual.c_str());
@@ -47,14 +47,14 @@ TEST(BleScanParserImplTest, Parse128BitUuid) {
 
 TEST(BleScanParserImplTest, Parse16BitServiceUuids) {
   std::vector<device::BluetoothUUID> expected = {
-      device::BluetoothUUID("0000ABCD-0000-1000-8000-00805F9B34FB"),
-      device::BluetoothUUID("0000EF01-0000-1000-8000-00805F9B34FB"),
-      device::BluetoothUUID("00002345-0000-1000-8000-00805F9B34FB"),
-      device::BluetoothUUID("00006789-0000-1000-8000-00805F9B34FB"),
-      device::BluetoothUUID("0000ABCD-0000-1000-8000-00805F9B34FB"),
-      device::BluetoothUUID("0000EF01-0000-1000-8000-00805F9B34FB"),
-      device::BluetoothUUID("00002345-0000-1000-8000-00805F9B34FB"),
-      device::BluetoothUUID("00006789-0000-1000-8000-00805F9B34FB"),
+      device::BluetoothUUID("0000CDAB-0000-1000-8000-00805F9B34FB"),
+      device::BluetoothUUID("000001EF-0000-1000-8000-00805F9B34FB"),
+      device::BluetoothUUID("00004523-0000-1000-8000-00805F9B34FB"),
+      device::BluetoothUUID("00008967-0000-1000-8000-00805F9B34FB"),
+      device::BluetoothUUID("0000CDAB-0000-1000-8000-00805F9B34FB"),
+      device::BluetoothUUID("000001EF-0000-1000-8000-00805F9B34FB"),
+      device::BluetoothUUID("00004523-0000-1000-8000-00805F9B34FB"),
+      device::BluetoothUUID("00008967-0000-1000-8000-00805F9B34FB"),
   };
 
   const uint8_t kUuids[] = {0xab, 0xcd, 0xef, 0x01, 0x23, 0x45, 0x67, 0x89,
@@ -68,10 +68,10 @@ TEST(BleScanParserImplTest, Parse16BitServiceUuids) {
 
 TEST(BleScanParserImplTest, Parse32BitServiceUuids) {
   std::vector<device::BluetoothUUID> expected = {
-      device::BluetoothUUID("ABCDEF01-0000-1000-8000-00805F9B34FB"),
-      device::BluetoothUUID("23456789-0000-1000-8000-00805F9B34FB"),
-      device::BluetoothUUID("ABCDEF01-0000-1000-8000-00805F9B34FB"),
-      device::BluetoothUUID("23456789-0000-1000-8000-00805F9B34FB"),
+      device::BluetoothUUID("01EFCDAB-0000-1000-8000-00805F9B34FB"),
+      device::BluetoothUUID("89674523-0000-1000-8000-00805F9B34FB"),
+      device::BluetoothUUID("01EFCDAB-0000-1000-8000-00805F9B34FB"),
+      device::BluetoothUUID("89674523-0000-1000-8000-00805F9B34FB"),
   };
 
   const uint8_t kUuids[] = {0xab, 0xcd, 0xef, 0x01, 0x23, 0x45, 0x67, 0x89,
@@ -85,8 +85,8 @@ TEST(BleScanParserImplTest, Parse32BitServiceUuids) {
 
 TEST(BleScanParserImplTest, Parse128BitServiceUuids) {
   std::vector<device::BluetoothUUID> expected = {
-      device::BluetoothUUID("ABCDEF01-2345-6789-ABCD-EF0123456789"),
-      device::BluetoothUUID("23456789-ABCD-EF01-ABCD-EF0123456789"),
+      device::BluetoothUUID("89674523-01EF-CDAB-8967-452301EFCDAB"),
+      device::BluetoothUUID("89674523-01EF-CDAB-01EF-CDAB89674523"),
   };
 
   const uint8_t kUuids[] = {0xab, 0xcd, 0xef, 0x01, 0x23, 0x45, 0x67, 0x89,
@@ -123,18 +123,18 @@ TEST(BleScanParserImplTest, ParseBleAdvertisingScan) {
       // Advertising flag = 0x42
       0x02, 0x01, 0x42,
       // 16-bit service UUIDs 0000abcd-... and 0000ef01-...
-      0x05, 0x02, 0xab, 0xcd, 0xef, 0x01,
+      0x05, 0x02, 0xcd, 0xab, 0x01, 0xef,
       // TX power = 0x1b
       0x02, 0x0a, 0x1b,
       // 32-bit service UUIDs abcdef01-... and 23456789-...
-      0x09, 0x05, 0xab, 0xcd, 0xef, 0x01, 0x23, 0x45, 0x67, 0x89,
+      0x09, 0x05, 0x01, 0xef, 0xcd, 0xab, 0x89, 0x67, 0x45, 0x23,
       // Local name 'Steve'
       0x06, 0x08, 0x53, 0x74, 0x65, 0x76, 0x65,
       // 128-bit service UUID abcdef01-2345-6789-abcd-ef0123456789
-      0x11, 0x06, 0xab, 0xcd, 0xef, 0x01, 0x23, 0x45, 0x67, 0x89, 0xab, 0xcd,
-      0xef, 0x01, 0x23, 0x45, 0x67, 0x89,
+      0x11, 0x06, 0x89, 0x67, 0x45, 0x23, 0x01, 0xef, 0xcd, 0xab, 0x89, 0x67,
+      0x45, 0x23, 0x01, 0xef, 0xcd, 0xab,
       // Service data map 0000dcab-... => { 0xa1, 0xb2, 0xc3, 0xd4, 0xe5 }
-      0x08, 0x16, 0xdc, 0xab, 0xa1, 0xb2, 0xc3, 0xd4, 0xe5,
+      0x08, 0x16, 0xab, 0xdc, 0xa1, 0xb2, 0xc3, 0xd4, 0xe5,
       // Manufacturer data map 0xd00d => { 0x1a, 0x2b, 0x3c, 0x4d }
       0x07, 0xff, 0x0d, 0xd0, 0x1a, 0x2b, 0x3c, 0x4d};