Add advertisement decoder

The decoder allows us to parse incoming Nearby Presence advertisements. PiperOrigin-RevId: 465146528
2026-09-16 15:36:12 -04:00 · 2022-08-03 14:18:12 -07:00
parent ecf51ff13d
commit 319e5abea4
4 changed files with 338 additions and 1 deletions
@@ -0,0 +1,145 @@
+// Copyright 2022 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "third_party/nearby/presence/implementation/advertisement_decoder.h"
+
+#include <string>
+#include <vector>
+
+#include "gmock/gmock.h"
+#include "protobuf-matchers/protocol-buffer-matchers.h"
+#include "gtest/gtest.h"
+#include "absl/strings/escaping.h"
+#include "third_party/nearby/presence/data_element.h"
+#include "third_party/nearby/presence/implementation/credential_manager_impl.h"
+
+namespace nearby {
+namespace presence {
+
+namespace {
+using ::testing::ElementsAre;
+using ::testing::Return;
+using ::testing::status::StatusIs;
+
+class MockCredentialManager : public CredentialManagerImpl {
+ public:
+  MOCK_METHOD(absl::StatusOr<std::string>, DecryptDataElements,
+              (absl::string_view metadata_key, absl::string_view salt,
+               absl::string_view data_elements),
+              (override));
+};
+
+TEST(AdvertisementDecoder, DecodeBaseNpPrivateAdvertisement) {
+  const std::string salt = "AB";
+  const std::string metadata =
+      absl::HexStringToBytes("1011121314151617181920212223");
+  MockCredentialManager credential_manager;
+  EXPECT_CALL(
+      credential_manager,
+      DecryptDataElements(metadata, salt, absl::HexStringToBytes("5051525354")))
+      .WillOnce(Return(absl::HexStringToBytes("18CD29EEFF")));
+
+  AdvertisementDecoder decoder(&credential_manager);
+
+  const absl::StatusOr<std::vector<DataElement>> result =
+      decoder.DecodeAdvertisement(absl::HexStringToBytes(
+          "00204142e110111213141516171819202122235051525354"));
+
+  ASSERT_OK(result);
+  EXPECT_THAT(
+      *result,
+      ElementsAre(DataElement(DataElement::kSaltFieldType, salt),
+                  DataElement(DataElement::kPrivateIdentityFieldType, metadata),
+                  DataElement(8, absl::HexStringToBytes("CD")),
+                  DataElement(9, absl::HexStringToBytes("EEFF"))));
+}
+
+TEST(AdvertisementDecoder, DecodeBaseNpPublicAdvertisement) {
+  const std::string salt = "AB";
+  MockCredentialManager credential_manager;
+  AdvertisementDecoder decoder(&credential_manager);
+
+  const absl::StatusOr<std::vector<DataElement>> result =
+      decoder.DecodeAdvertisement(
+          absl::HexStringToBytes("002041420318CD29EEFF"));
+
+  ASSERT_OK(result);
+  EXPECT_THAT(
+      *result,
+      ElementsAre(DataElement(DataElement::kSaltFieldType, salt),
+                  DataElement(DataElement::kPublicIdentityFieldType, ""),
+                  DataElement(8, absl::HexStringToBytes("CD")),
+                  DataElement(9, absl::HexStringToBytes("EEFF"))));
+}
+
+TEST(AdvertisementDecoder, InvalidAdvertisementFieldTooShort) {
+  MockCredentialManager credential_manager;
+  AdvertisementDecoder decoder(&credential_manager);
+
+  // 0x50 header means 5 bytes long salt but only 4 bytes follow.
+  EXPECT_THAT(
+      decoder.DecodeAdvertisement(absl::HexStringToBytes("0050A0A1A2A3")),
+      StatusIs(absl::StatusCode::kOutOfRange));
+}
+
+TEST(AdvertisementDecoder, ZeroLengthPayload) {
+  MockCredentialManager credential_manager;
+  AdvertisementDecoder decoder(&credential_manager);
+
+  // A action with type 0xA and no payload
+  const absl::StatusOr<std::vector<DataElement>> result =
+      decoder.DecodeAdvertisement(absl::HexStringToBytes("000A"));
+
+  ASSERT_OK(result);
+  EXPECT_THAT(*result, ElementsAre(DataElement(0xA, "")));
+}
+
+TEST(AdvertisementDecoder, EmptyAdvertisement) {
+  MockCredentialManager credential_manager;
+  AdvertisementDecoder decoder(&credential_manager);
+
+  EXPECT_THAT(decoder.DecodeAdvertisement(""),
+              StatusIs(absl::StatusCode::kOutOfRange));
+}
+
+TEST(AdvertisementDecoder, InvalidEncryptedContent) {
+  const std::string salt = "AB";
+  const std::string metadata =
+      absl::HexStringToBytes("1011121314151617181920212223");
+  MockCredentialManager credential_manager;
+  // 0x28CD is an invalid DE, 0x28 means a 2 byte payload with type 8 alas only
+  // one byte is given (0xCD)
+  EXPECT_CALL(
+      credential_manager,
+      DecryptDataElements(metadata, salt, absl::HexStringToBytes("5051525354")))
+      .WillOnce(Return(absl::HexStringToBytes("28CD")));
+  AdvertisementDecoder decoder(&credential_manager);
+
+  EXPECT_THAT(decoder.DecodeAdvertisement(absl::HexStringToBytes(
+                  "00204142e110111213141516171819202122235051525354")),
+              StatusIs(absl::StatusCode::kOutOfRange));
+}
+
+TEST(AdvertisementDecoder, UnsupportedAdvertisementVersion) {
+  MockCredentialManager credential_manager;
+  AdvertisementDecoder decoder(&credential_manager);
+
+  EXPECT_THAT(decoder.DecodeAdvertisement(
+                  absl::HexStringToBytes("012041420318CD29EEFF")),
+              StatusIs(absl::StatusCode::kUnimplemented));
+}
+
+}  // namespace
+}  // namespace presence
+}  // namespace nearby