Make use of address candidates in Hotspot credentials.

PiperOrigin-RevId: 830572287

connections/implementation/BUILD

@@ -270,6 +270,7 @@ cc_test(
         "//internal/proto/analytics:connections_log_cc_proto",
         "//proto:connections_enums_cc_proto",
         "@com_github_protobuf_matchers//protobuf-matchers",
+        "@com_google_absl//absl/container:flat_hash_map",
         "@com_google_absl//absl/strings",
         "@com_google_absl//absl/time",
         "@com_google_googletest//:gtest_main",

connections/implementation/bwu_manager_test.cc

@@ -19,8 +19,10 @@
 #include <utility>
 
 #include "gtest/gtest.h"
+#include "absl/container/flat_hash_map.h"
 #include "absl/strings/string_view.h"
 #include "connections/connection_options.h"
+#include "connections/implementation/bwu_handler.h"
 #include "connections/implementation/client_proxy.h"
 #include "connections/implementation/endpoint_channel.h"
 #include "connections/implementation/endpoint_channel_manager.h"
@@ -32,8 +34,10 @@
 #include "connections/implementation/offline_frames.h"
 #include "connections/implementation/service_id_constants.h"
 #include "connections/listeners.h"
+#include "connections/medium_selector.h"
 #include "internal/flags/nearby_flags.h"
 #include "internal/platform/byte_array.h"
+#include "internal/platform/count_down_latch.h"
 #include "internal/platform/exception.h"
 #include "internal/platform/feature_flags.h"
 #include "internal/proto/analytics/connections_log.pb.h"
@@ -60,6 +64,25 @@ constexpr absl::string_view kEndpointId3 = "Endpoint3";
 constexpr absl::string_view kEndpointId4 = "Endpoint4";
 constexpr absl::string_view kEndpointId5 = "Endpoint5";
 
+BandwidthUpgradeNegotiationFrame::UpgradePathInfo::WifiHotspotCredentials
+CreateWifiHotspotCredentials() {
+  BandwidthUpgradeNegotiationFrame::UpgradePathInfo::WifiHotspotCredentials
+      credentials;
+  credentials.set_ssid("Direct-357a2d8c");
+  credentials.set_password("b592f7d3");
+  credentials.set_port(1234);
+  credentials.set_frequency(2412);
+  credentials.set_gateway("123.234.23.1");
+  auto* candidate = credentials.mutable_address_candidates()->Add();
+  candidate->set_ip_address(std::string(
+      "\xfe\x80\\x00\x00\x00\x00\x00\x00\x4d\xb2\xb3\x5c\x22\x03\x98\xa1", 16));
+  candidate->set_port(1234);
+  candidate = credentials.mutable_address_candidates()->Add();
+  candidate->set_ip_address("\x7b\xea\x17\x01");
+  candidate->set_port(2412);
+  return credentials;
+}
+
 class BwuManagerTest : public ::testing::Test {
  protected:
   BwuManagerTest() {
@@ -928,9 +951,9 @@ TEST_F(BwuManagerTest, InitiateBwu_Revert_OnDisconnect_Hotspot) {
 
   ExceptionOr<OfflineFrame> hotspot_path_available_frame =
       parser::FromBytes(parser::ForBwuWifiHotspotPathAvailable(
-          /*ssid=*/"Direct-357a2d8c", /*password=*/"b592f7d3",
-          /*port=*/1234, /*frequency=*/2412, /*gateway=*/"123.234.23.1",
-          false));
+          CreateWifiHotspotCredentials(),
+          /*supports_disabling_encryption=*/false));
+  ASSERT_TRUE(hotspot_path_available_frame.ok());
   OfflineFrame frame = hotspot_path_available_frame.result();
   frame.set_version(OfflineFrame::V1);
   auto* v1_frame = frame.mutable_v1();
@@ -995,8 +1018,8 @@ TEST_F(BwuManagerTest, BlockBwuFrameBeforeAccept) {
 
   ExceptionOr<OfflineFrame> hotspot_path_available_frame2 =
       parser::FromBytes(parser::ForBwuWifiHotspotPathAvailable(
-          /*ssid=*/"Direct-357a2d8c", /*password=*/"b592f7d3",
-          /*port=*/1234, /*frequency=*/2412, /*gateway=*/"123.234.23.1", true));
+          CreateWifiHotspotCredentials(),
+          /*supports_disabling_encryption=*/true));
   OfflineFrame frame2 = hotspot_path_available_frame2.result();
   frame2.set_version(OfflineFrame::V1);
   auto* v1_frame2 = frame2.mutable_v1();
@@ -1018,8 +1041,8 @@ TEST_F(BwuManagerTest, BlockBwuFrameBeforeAccept) {
 TEST_F(BwuManagerTest, BlockBwuFrameFromAdvertiser) {
   ExceptionOr<OfflineFrame> hotspot_path_available_frame =
       parser::FromBytes(parser::ForBwuWifiHotspotPathAvailable(
-          /*ssid=*/"Direct-357a2d8c", /*password=*/"b592f7d3",
-          /*port=*/1234, /*frequency=*/2412, /*gateway=*/"123.234.23.1", true));
+          CreateWifiHotspotCredentials(),
+          /*supports_disabling_encryption=*/true));
   OfflineFrame frame = hotspot_path_available_frame.result();
   frame.set_version(OfflineFrame::V1);
   auto* v1_frame = frame.mutable_v1();

connections/implementation/fake_bwu_handler.h

@@ -152,11 +152,25 @@ class FakeBwuHandler : public BaseBwuHandler {
         return parser::ForBwuWebrtcPathAvailable(
             /*peer_id=*/"peer-id",
             location::nearby::connections::LocationHint{});
-      case location::nearby::proto::connections::WIFI_HOTSPOT:
-        return parser::ForBwuWifiHotspotPathAvailable(
-            /*ssid=*/"Direct-357a2d8c", /*password=*/"b592f7d3",
-            /*port=*/1234, /*frequency=*/2412, /*gateway=*/"123.234.23.1",
-            false);
+      case location::nearby::proto::connections::WIFI_HOTSPOT: {
+        location::nearby::connections::BandwidthUpgradeNegotiationFrame::
+            UpgradePathInfo::WifiHotspotCredentials credentials;
+        credentials.set_ssid("Direct-357a2d8c");
+        credentials.set_password("b592f7d3");
+        credentials.set_port(1234);
+        credentials.set_frequency(2412);
+        credentials.set_gateway("123.234.23.1");
+        auto* candidate = credentials.mutable_address_candidates()->Add();
+        candidate->set_ip_address(std::string(
+            "\xfe\x80\x00\x00\x00\x00\x00\x00\x4d\xb2\xb3\x5c\x22\x03\x98\xa1",
+            16));
+        candidate->set_port(1234);
+        candidate = credentials.mutable_address_candidates()->Add();
+        candidate->set_ip_address("\x7b\xea\x17\x01");
+        candidate->set_port(2412);
+        return parser::ForBwuWifiHotspotPathAvailable(std::move(credentials),
+                                                      false);
+      }
       case location::nearby::proto::connections::WIFI_DIRECT:
         return parser::ForBwuWifiDirectPathAvailable(
             /*ssid=*/"Direct-12345678", /*password=*/"87654321", /*port=*/2143,

connections/implementation/mediums/wifi_hotspot.cc

@@ -17,6 +17,7 @@
 #include <cstdint>
 #include <string>
 #include <utility>
+#include <vector>
 
 #include "absl/strings/string_view.h"
 #include "absl/time/clock.h"
@@ -256,7 +257,8 @@ bool WifiHotspot::IsAcceptingConnectionsLocked(const std::string& service_id) {
 }
 
 ErrorOr<WifiHotspotSocket> WifiHotspot::Connect(
-    const std::string& service_id, const ServiceAddress& service_address,
+    const std::string& service_id,
+    const std::vector<ServiceAddress>& service_addresses,
     CancellationFlag* cancellation_flag) {
   MutexLock lock(&mutex_);
   if (service_id.empty()) {
@@ -264,6 +266,11 @@ ErrorOr<WifiHotspotSocket> WifiHotspot::Connect(
                  "service_id is empty.";
     return {Error(OperationResultCode::NEARBY_LOCAL_CLIENT_STATE_WRONG)};
   }
+  if (service_addresses.empty()) {
+    LOG(INFO) << "No service address found for service_id: " << service_id;
+    return {Error(
+        OperationResultCode::MEDIUM_UNAVAILABLE_WIFI_HOTSPOT_NOT_AVAILABLE)};
+  }
 
   if (!IsClientAvailableLocked()) {
     LOG(INFO) << "Can't create client WifiHotspot socket [service_id="
@@ -288,13 +295,18 @@ ErrorOr<WifiHotspotSocket> WifiHotspot::Connect(
   // Socket to return. To allow for NRVO to work, it has to be a single object.
   WifiHotspotSocket socket;
   for (int i = 0; i < wifi_hotspot_max_connection_retries; ++i) {
-    if (cancellation_flag->Cancelled()) {
-      LOG(INFO) << "connect to service has been cancelled.";
-      return {Error(
-          OperationResultCode::
-              CLIENT_CANCELLATION_CANCEL_WIFI_HOTSPOT_OUTGOING_CONNECTION)};
+    for (const auto& service_address : service_addresses) {
+      if (cancellation_flag->Cancelled()) {
+        LOG(INFO) << "connect to service has been cancelled.";
+        return {Error(
+            OperationResultCode::
+                CLIENT_CANCELLATION_CANCEL_WIFI_HOTSPOT_OUTGOING_CONNECTION)};
+      }
+      socket = medium_.ConnectToService(service_address, cancellation_flag);
+      if (socket.IsValid()) {
+        break;
+      }
     }
-    socket = medium_.ConnectToService(service_address, cancellation_flag);
     if (socket.IsValid()) {
       break;
     }

connections/implementation/mediums/wifi_hotspot.h

@@ -16,6 +16,7 @@
 #define CORE_INTERNAL_MEDIUMS_WIFI_HOTSPOT_H_
 
 #include <string>
+#include <vector>
 
 #include "absl/base/thread_annotations.h"
 #include "absl/container/flat_hash_map.h"
@@ -74,10 +75,10 @@ class WifiHotspot {
   // bandwidth upgradation.
   // Returns socket instance. On success, WifiHotspotSocket.IsValid() return
   // true.
-  ErrorOr<WifiHotspotSocket> Connect(const std::string& service_id,
-                                     const ServiceAddress& service_address,
-                                     CancellationFlag* cancellation_flag)
-      ABSL_LOCKS_EXCLUDED(mutex_);
+  ErrorOr<WifiHotspotSocket> Connect(
+      const std::string& service_id,
+      const std::vector<ServiceAddress>& service_addresses,
+      CancellationFlag* cancellation_flag) ABSL_LOCKS_EXCLUDED(mutex_);
 
   // Gets SoftAP ssid + password + ip address + gateway + port etc for remote
   // services on the network to identify and connect to this service.

connections/implementation/mediums/wifi_hotspot_test.cc

@@ -120,11 +120,11 @@ TEST_P(WifiHotspotTest, CanStartHotspotThatOtherConnect) {
   };
   CancellationFlag flag;
   ErrorOr<WifiHotspotSocket> socket_result =
-      wifi_hotspot_b->Connect(service_id, service_address, &flag);
+      wifi_hotspot_b->Connect(service_id, {service_address}, &flag);
   EXPECT_TRUE(socket_result.has_error());
 
   socket_result = wifi_hotspot_b->Connect(
-      service_id, hotspot_credentials->GetAddressCandidates().back(), &flag);
+      service_id, hotspot_credentials->GetAddressCandidates(), &flag);
   EXPECT_TRUE(socket_result.has_value());
   EXPECT_TRUE(socket_result.value().IsValid());
 
@@ -155,7 +155,7 @@ TEST_P(WifiHotspotTest, CanStartHotspotThatOtherCanCancelConnect) {
 
   CancellationFlag flag(true);
   ErrorOr<WifiHotspotSocket> socket_result = wifi_hotspot_b->Connect(
-      service_id, hotspot_credentials->GetAddressCandidates().back(), &flag);
+      service_id, hotspot_credentials->GetAddressCandidates(), &flag);
 
   // If FeatureFlag is disabled, Cancelled is false as no-op.
   if (!feature_flags.enable_cancellation_flag) {

connections/implementation/offline_frames.cc

@@ -258,12 +258,10 @@ ByteArray ForPayloadAckPayloadTransfer(std::int64_t payload_id) {
   return ToBytes(std::move(frame));
 }
 
-ByteArray ForBwuWifiHotspotPathAvailable(const std::string& ssid,
-                                         const std::string& password,
-                                         std::int32_t port,
-                                         std::int32_t frequency,
-                                         const std::string& gateway,
-                                         bool supports_disabling_encryption) {
+ByteArray ForBwuWifiHotspotPathAvailable(
+    BandwidthUpgradeNegotiationFrame::UpgradePathInfo::WifiHotspotCredentials
+        credentials,
+    bool supports_disabling_encryption) {
   OfflineFrame frame;
 
   frame.set_version(OfflineFrame::V1);
@@ -279,12 +277,7 @@ ByteArray ForBwuWifiHotspotPathAvailable(const std::string& ssid,
       supports_disabling_encryption);
   auto* wifi_hotspot_credentials =
       upgrade_path_info->mutable_wifi_hotspot_credentials();
-  wifi_hotspot_credentials->set_ssid(ssid);
-  wifi_hotspot_credentials->set_password(password);
-  wifi_hotspot_credentials->set_port(port);
-  wifi_hotspot_credentials->set_frequency(frequency);
-  wifi_hotspot_credentials->set_gateway(gateway);
-
+  *wifi_hotspot_credentials = std::move(credentials);
   return ToBytes(std::move(frame));
 }
 

connections/implementation/offline_frames.h

@@ -75,12 +75,10 @@ ByteArray ForPayloadAckPayloadTransfer(std::int64_t payload_id);
 ByteArray ForBwuIntroduction(const std::string& endpoint_id,
                              bool supports_disabling_encryption);
 ByteArray ForBwuIntroductionAck();
-ByteArray ForBwuWifiHotspotPathAvailable(const std::string& ssid,
-                                         const std::string& password,
-                                         std::int32_t port,
-                                         std::int32_t frequency,
-                                         const std::string& gateway,
-                                         bool supports_disabling_encryption);
+ByteArray ForBwuWifiHotspotPathAvailable(
+    location::nearby::connections::BandwidthUpgradeNegotiationFrame::
+        UpgradePathInfo::WifiHotspotCredentials credentials,
+    bool supports_disabling_encryption);
 ByteArray ForBwuWifiLanPathAvailable(
     const std::vector<std::string>& ip_addresses, std::int32_t port);
 ByteArray ForBwuAwdlPathAvailable(const std::string& service_name,

connections/implementation/offline_frames_test.cc

@@ -17,6 +17,7 @@
 #include <array>
 #include <memory>
 #include <string>
+#include <utility>
 #include <vector>
 
 #include "gmock/gmock.h"
@@ -35,6 +36,7 @@ namespace connections {
 namespace parser {
 namespace {
 
+using ::location::nearby::connections::BandwidthUpgradeNegotiationFrame;
 using ::location::nearby::connections::OfflineFrame;
 using ::location::nearby::connections::OsInfo;
 using ::location::nearby::connections::PayloadTransferFrame;
@@ -396,14 +398,33 @@ TEST(OfflineFramesTest, CanGenerateBwuWifiHotspotPathAvailable) {
             port: 1234
             gateway: "0.0.0.0"
             frequency: 2412
+            address_candidates: <
+              ip_address: "\xfe\x80\x00\x00\x00\x00\x00\x00\x4d\xb2\xb3\x5c\x22\x03\x98\xa1"
+              port: 1234
+            >
+            address_candidates: < ip_address: "\xc0\xa8\x00\x01" port: 5678 >
           >
           supports_disabling_encryption: false
           supports_client_introduction_ack: true
         >
       >
     >)pb";
-  ByteArray bytes = ForBwuWifiHotspotPathAvailable(
-      "ssid", "password", 1234, /*frequency=*/2412, "0.0.0.0", false);
+  BandwidthUpgradeNegotiationFrame::UpgradePathInfo::WifiHotspotCredentials
+      credentials;
+  credentials.set_ssid("ssid");
+  credentials.set_password("password");
+  credentials.set_port(1234);
+  credentials.set_frequency(2412);
+  credentials.set_gateway("0.0.0.0");
+  auto* address_candidate = credentials.add_address_candidates();
+  address_candidate->set_ip_address(std::string(
+      "\xfe\x80\x00\x00\x00\x00\x00\x00\x4d\xb2\xb3\x5c\x22\x03\x98\xa1", 16));
+  address_candidate->set_port(1234);
+  address_candidate = credentials.add_address_candidates();
+  address_candidate->set_ip_address(std::string("\xc0\xa8\x00\x01", 4));
+  address_candidate->set_port(5678);
+  ByteArray bytes =
+      ForBwuWifiHotspotPathAvailable(std::move(credentials), false);
   auto response = FromBytes(bytes);
   ASSERT_TRUE(response.ok());
   OfflineFrame message = response.result();

connections/implementation/offline_frames_validator.cc

@@ -232,13 +232,24 @@ Exception EnsureValidBandwidthUpgradeWifiHotspotPathAvailableFrame(
       !WithinRange(wifi_hotspot_credentials.password().length(),
                    kWifiPasswordSsidMinLength, kWifiPasswordSsidMaxLength))
     return {Exception::kInvalidProtocolBuffer};
-  if (!wifi_hotspot_credentials.has_gateway())
+  if (!wifi_hotspot_credentials.has_gateway() &&
+      wifi_hotspot_credentials.address_candidates_size() == 0)
     return {Exception::kInvalidProtocolBuffer};
   const std::regex ip4_pattern(std::string(kIpv4PatternString).c_str());
-  const std::regex ip6_pattern(std::string(kIpv6PatternString).c_str());
-  if (!(std::regex_match(wifi_hotspot_credentials.gateway(), ip4_pattern) ||
-        std::regex_match(wifi_hotspot_credentials.gateway(), ip6_pattern)))
-    return {Exception::kInvalidProtocolBuffer};
+  if (!wifi_hotspot_credentials.gateway().empty() &&
+      !(std::regex_match(wifi_hotspot_credentials.gateway(), ip4_pattern))) {
+      return {Exception::kInvalidProtocolBuffer};
+  }
+  for (const auto& address_candidate :
+       wifi_hotspot_credentials.address_candidates()) {
+    if (!address_candidate.has_ip_address() || !address_candidate.has_port()) {
+      return {Exception::kInvalidProtocolBuffer};
+    }
+    if (address_candidate.ip_address().size() != 4 &&
+        address_candidate.ip_address().size() != 16) {
+      return {Exception::kInvalidProtocolBuffer};
+    }
+  }
 
   // For backwards compatibility reasons, no other fields should be null-checked
   // for this frame. Parameter checking (eg. must be within this range) is fine.

connections/implementation/offline_frames_validator_test.cc

@@ -16,18 +16,23 @@
 
 #include <array>
 #include <string>
+#include <utility>
 
 #include "gtest/gtest.h"
 #include "absl/strings/string_view.h"
+#include "connections/connection_options.h"
 #include "connections/implementation/offline_frames.h"
 #include "connections/implementation/proto/offline_wire_formats.pb.h"
+#include "connections/medium_selector.h"
 #include "internal/platform/byte_array.h"
+#include "internal/platform/exception.h"
 
 namespace nearby {
 namespace connections {
 namespace parser {
 namespace {
 
+using ::location::nearby::connections::BandwidthUpgradeNegotiationFrame;
 using ::location::nearby::connections::OfflineFrame;
 using ::location::nearby::connections::OsInfo;
 using ::location::nearby::connections::PayloadTransferFrame;
@@ -588,12 +593,18 @@ TEST(OfflineFramesValidatorTest,
 }
 
 TEST(OfflineFramesValidatorTest,
-     ValidatesAsOkWithValidBandwidthUpgradeNegotiationFrame) {
+     ValidateHotspotUpgradeFrameWithGatewaySucceeds) {
   OfflineFrame offline_frame;
 
+  BandwidthUpgradeNegotiationFrame::UpgradePathInfo::WifiHotspotCredentials
+      credentials;
+  credentials.set_ssid(kSsid);
+  credentials.set_password(kPassword);
+  credentials.set_port(kPort);
+  credentials.set_frequency(kHotspotFrequency);
+  credentials.set_gateway(kWifiHotspotGateway);
   ByteArray bytes = ForBwuWifiHotspotPathAvailable(
-      std::string(kSsid), std::string(kPassword), kPort, kHotspotFrequency,
-      std::string(kWifiHotspotGateway), kSupportsDisablingEncryption);
+      std::move(credentials), kSupportsDisablingEncryption);
   offline_frame.ParseFromString(std::string(bytes));
 
   auto ret_value = EnsureValidOfflineFrame(offline_frame);
@@ -601,13 +612,87 @@ TEST(OfflineFramesValidatorTest,
   EXPECT_TRUE(ret_value.Ok());
 }
 
+TEST(OfflineFramesValidatorTest,
+     ValidateHotspotUpgradeFrameWithAddressCandidatesSucceeds) {
+  OfflineFrame offline_frame;
+
+  BandwidthUpgradeNegotiationFrame::UpgradePathInfo::WifiHotspotCredentials
+      credentials;
+  credentials.set_ssid(kSsid);
+  credentials.set_password(kPassword);
+  credentials.set_frequency(kHotspotFrequency);
+  auto* candidate = credentials.mutable_address_candidates()->Add();
+  candidate->set_ip_address(std::string(
+      "\xfe\x80\x00\x00\x00\x00\x00\x00\x4d\xb2\xb3\x5c\x22\x03\x98\xa1", 16));
+  candidate->set_port(kPort);
+  candidate = credentials.mutable_address_candidates()->Add();
+  candidate->set_ip_address(std::string("\xc0\xa8\x00\x01", 4));
+  candidate->set_port(kPort);
+  ByteArray bytes = ForBwuWifiHotspotPathAvailable(
+      std::move(credentials), kSupportsDisablingEncryption);
+  offline_frame.ParseFromString(std::string(bytes));
+
+  auto ret_value = EnsureValidOfflineFrame(offline_frame);
+
+  EXPECT_TRUE(ret_value.Ok());
+}
+
+TEST(OfflineFramesValidatorTest,
+     ValidateHotspotUpgradeFrameWithInvlaidAddressCandidatesLengthFails) {
+  OfflineFrame offline_frame;
+
+  BandwidthUpgradeNegotiationFrame::UpgradePathInfo::WifiHotspotCredentials
+      credentials;
+  credentials.set_ssid(kSsid);
+  credentials.set_password(kPassword);
+  credentials.set_frequency(kHotspotFrequency);
+  auto* candidate = credentials.mutable_address_candidates()->Add();
+  candidate->set_ip_address(std::string(
+      "\xfe\x80\x00\x00\x00\x00\x00\x00\x4d\xb2\xb3\x5c\x22\x03\x98\xa1", 12));
+  candidate->set_port(kPort);
+  ByteArray bytes = ForBwuWifiHotspotPathAvailable(
+      std::move(credentials), kSupportsDisablingEncryption);
+  offline_frame.ParseFromString(std::string(bytes));
+
+  auto ret_value = EnsureValidOfflineFrame(offline_frame);
+
+  EXPECT_FALSE(ret_value.Ok());
+}
+
+TEST(OfflineFramesValidatorTest,
+     ValidateHotspotUpgradeFrameWithAddressCandidatesNoPortFails) {
+  OfflineFrame offline_frame;
+
+  BandwidthUpgradeNegotiationFrame::UpgradePathInfo::WifiHotspotCredentials
+      credentials;
+  credentials.set_ssid(kSsid);
+  credentials.set_password(kPassword);
+  credentials.set_frequency(kHotspotFrequency);
+  auto* candidate = credentials.mutable_address_candidates()->Add();
+  candidate->set_ip_address(std::string(
+      "\xfe\x80\x00\x00\x00\x00\x00\x00\x4d\xb2\xb3\x5c\x22\x03\x98\xa1", 16));
+  ByteArray bytes = ForBwuWifiHotspotPathAvailable(
+      std::move(credentials), kSupportsDisablingEncryption);
+  offline_frame.ParseFromString(std::string(bytes));
+
+  auto ret_value = EnsureValidOfflineFrame(offline_frame);
+
+  EXPECT_FALSE(ret_value.Ok());
+}
+
 TEST(OfflineFramesValidatorTest,
      ValidatesAsFailWithNullBandwidthUpgradeNegotiationFrame) {
   OfflineFrame offline_frame;
 
+  BandwidthUpgradeNegotiationFrame::UpgradePathInfo::WifiHotspotCredentials
+      credentials;
+  credentials.set_ssid(kSsid);
+  credentials.set_password(kPassword);
+  credentials.set_port(kPort);
+  credentials.set_frequency(kHotspotFrequency);
+  credentials.set_gateway(kWifiHotspotGateway);
   ByteArray bytes = ForBwuWifiHotspotPathAvailable(
-      std::string(kSsid), std::string(kPassword), kPort, kHotspotFrequency,
-      std::string(kWifiHotspotGateway), kSupportsDisablingEncryption);
+      std::move(credentials), kSupportsDisablingEncryption);
   offline_frame.ParseFromString(std::string(bytes));
   auto* v1_frame = offline_frame.mutable_v1();
 

connections/implementation/wifi_hotspot_bwu_handler.cc

@@ -33,11 +33,13 @@
 #include "connections/implementation/endpoint_channel.h"
 #include "connections/implementation/mediums/mediums.h"
 #include "connections/implementation/offline_frames.h"
+#include "connections/implementation/proto/offline_wire_formats.pb.h"
 #include "connections/implementation/wifi_hotspot_endpoint_channel.h"
 #include "connections/strategy.h"
 #include "internal/base/masker.h"
 #include "internal/platform/byte_array.h"
 #include "internal/platform/expected.h"
+#include "internal/platform/implementation/wifi_utils.h"
 #include "internal/platform/logging.h"
 #include "internal/platform/wifi_credential.h"
 #include "internal/platform/wifi_hotspot.h"
@@ -46,6 +48,7 @@ namespace nearby {
 namespace connections {
 
 namespace {
+using ::location::nearby::connections::BandwidthUpgradeNegotiationFrame;
 using ::location::nearby::proto::connections::OperationResultCode;
 
 std::vector<char> GatewayToAddressBytes(const std::string& gateway) {
@@ -106,18 +109,42 @@ ByteArray WifiHotspotBwuHandler::HandleInitializeUpgradedMediumForEndpoint(
       wifi_hotspot_medium_.GetCredentials(upgrade_service_id);
   std::string ssid = hotspot_crendential->GetSSID();
   std::string password = hotspot_crendential->GetPassword();
-  std::string gateway = hotspot_crendential->GetGateway();
-  std::int32_t port = hotspot_crendential->GetPort();
   std::int32_t frequency = hotspot_crendential->GetFrequency();
 
   LOG(INFO) << "Start SoftAP with SSID:" << ssid
-            << ",  Password:" << masker::Mask(password) << ",  Port:" << port
-            << ",  Gateway:" << gateway << ",  Frequency:" << frequency;
+            << ",  Password:" << masker::Mask(password)
+            << ",  Frequency:" << frequency;
 
+  BandwidthUpgradeNegotiationFrame::UpgradePathInfo::WifiHotspotCredentials
+      credentials;
+  credentials.set_ssid(ssid);
+  credentials.set_password(password);
+  credentials.set_frequency(frequency);
+  const std::vector<ServiceAddress>& address_candidates =
+      hotspot_crendential->GetAddressCandidates();
+  for (const auto& service_address : address_candidates) {
+    // service address must be either 4 bytes (IPv4) or 16 bytes (IPv6).
+    if (service_address.address.size() != 4 &&
+        service_address.address.size() != 16) {
+      LOG(WARNING) << "Invalid service address size: "
+                   << service_address.address.size();
+      continue;
+    }
+    auto* service_address_proto = credentials.add_address_candidates();
+    service_address_proto->set_ip_address(std::string(
+        service_address.address.begin(), service_address.address.end()));
+    service_address_proto->set_port(service_address.port);
+  }
+  const ServiceAddress& last_service_address = address_candidates.back();
+  // We assume the last service address is IPv4.
+  credentials.set_gateway(WifiUtils::GetHumanReadableIpAddress(
+      std::string(last_service_address.address.begin(),
+                  last_service_address.address.end())));
+  credentials.set_port(last_service_address.port);
   bool disabling_encryption =
       (client->GetAdvertisingOptions().strategy == Strategy::kP2pPointToPoint);
   return parser::ForBwuWifiHotspotPathAvailable(
-      ssid, password, port, frequency, gateway,
+      std::move(credentials),
       /* supports_disabling_encryption */ disabling_encryption);
 }
 
@@ -148,15 +175,44 @@ WifiHotspotBwuHandler::CreateUpgradedEndpointChannel(
   HotspotCredentials hotspot_credentials;
   hotspot_credentials.SetSSID(upgrade_path_info_credentials.ssid());
   hotspot_credentials.SetPassword(upgrade_path_info_credentials.password());
-  hotspot_credentials.SetGateway(upgrade_path_info_credentials.gateway());
-  hotspot_credentials.SetPort(upgrade_path_info_credentials.port());
   hotspot_credentials.SetFrequency(upgrade_path_info_credentials.frequency());
+  std::vector<ServiceAddress> service_addresses;
+  for (const auto& service_address :
+       upgrade_path_info_credentials.address_candidates()) {
+    // service address must be either 4 bytes (IPv4) or 16 bytes (IPv6).
+    if (service_address.ip_address().size() != 4 &&
+        service_address.ip_address().size() != 16) {
+      LOG(WARNING) << "Invalid service address size: "
+                   << service_address.ip_address().size();
+      continue;
+    }
+    service_addresses.push_back(ServiceAddress{
+        .address = {service_address.ip_address().begin(),
+                    service_address.ip_address().end()},
+        .port = static_cast<uint16_t>(service_address.port()),
+    });
+  }
+  // Add gateway and port to address candidates if address candidates is empty.
+  if (service_addresses.empty() &&
+      upgrade_path_info_credentials.has_gateway()) {
+    std::vector<char> address_bytes =
+        GatewayToAddressBytes(upgrade_path_info_credentials.gateway());
+    if (!address_bytes.empty()) {
+      service_addresses.push_back(ServiceAddress{
+          .address = std::move(address_bytes),
+          .port = static_cast<uint16_t>(upgrade_path_info_credentials.port())});
+    }
+  }
+  if (service_addresses.empty()) {
+    LOG(ERROR) << "No service address found.";
+    return {Error(
+        OperationResultCode::CONNECTIVITY_WIFI_HOTSPOT_INVALID_CREDENTIAL)};
+  }
+  hotspot_credentials.SetAddressCandidates(std::move(service_addresses));
 
   LOG(INFO) << "Received Hotspot credential SSID: "
             << hotspot_credentials.GetSSID()
             << ",  Password:" << masker::Mask(hotspot_credentials.GetPassword())
-            << ",  Port:" << hotspot_credentials.GetPort()
-            << ",  Gateway:" << hotspot_credentials.GetGateway()
             << ",  Frequency:" << hotspot_credentials.GetFrequency();
 
   if (!wifi_hotspot_medium_.ConnectWifiHotspot(hotspot_credentials)) {
@@ -165,23 +221,18 @@ WifiHotspotBwuHandler::CreateUpgradedEndpointChannel(
         OperationResultCode::CONNECTIVITY_WIFI_HOTSPOT_INVALID_CREDENTIAL)};
   }
 
-  ServiceAddress service_address;
-  service_address.address =
-      GatewayToAddressBytes(hotspot_credentials.GetGateway());
-  service_address.port = hotspot_credentials.GetPort();
   ErrorOr<WifiHotspotSocket> socket_result = wifi_hotspot_medium_.Connect(
-      service_id, service_address, client->GetCancellationFlag(endpoint_id));
+      service_id, hotspot_credentials.GetAddressCandidates(),
+      client->GetCancellationFlag(endpoint_id));
   if (socket_result.has_error()) {
-    LOG(ERROR)
-        << "WifiHotspotBwuHandler failed to connect to the WifiHotspot service("
-        << hotspot_credentials.GetGateway() << ":"
-        << hotspot_credentials.GetPort() << ") for endpoint " << endpoint_id;
+    LOG(ERROR) << "WifiHotspotBwuHandler failed to connect to the WifiHotspot "
+                  "service for endpoint "
+               << endpoint_id;
     return {Error(socket_result.error().operation_result_code().value())};
   }
   VLOG(1)
-      << "WifiHotspotBwuHandler successfully connected to WifiHotspot service ("
-      << hotspot_credentials.GetGateway() << ":"
-      << hotspot_credentials.GetPort() << ") while upgrading endpoint "
+      << "WifiHotspotBwuHandler successfully connected to WifiHotspot service "
+         "while upgrading endpoint "
       << endpoint_id;
 
   // Create a new WifiHotspotEndpointChannel.