ios: nearbyConnections: Move source to //third_party.

PiperOrigin-RevId: 408046875

cpp/platform/impl/ios/Source/Mediums/BUILD

@@ -0,0 +1,57 @@
+load("//tools/build_defs/apple:objc.bzl", "objc_proto_library")
+
+# Copyright 2020 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.
+licenses(["notice"])
+
+package(default_visibility = ["//platform/impl/ios:__subpackages__"])
+
+objc_library(
+    name = "Mediums",
+    srcs = [
+        "GNCLeaks.m",
+        "GNCMConnection.m",
+        "WifiLan/GNCMBonjourBrowser.m",
+        "WifiLan/GNCMBonjourConnection.m",
+        "WifiLan/GNCMBonjourService.m",
+        "WifiLan/GNCMBonjourUtils.m",
+    ],
+    hdrs = [
+        "GNCLeaks.h",
+        "GNCMConnection.h",
+        "WifiLan/GNCMBonjourBrowser.h",
+        "WifiLan/GNCMBonjourConnection.h",
+        "WifiLan/GNCMBonjourService.h",
+        "WifiLan/GNCMBonjourUtils.h",
+    ],
+    deps = [
+        ":ObjCProtos",
+        "//base",
+        "//absl/numeric:int128",
+        "//platform/impl/ios/Source/Shared",
+        "//third_party/objective_c/google_toolbox_for_mac:GTM_Logger",
+    ],
+)
+
+objc_proto_library(
+    name = "ObjCProtos",
+    deps = [":Protos"],
+)
+
+proto_library(
+    name = "Protos",
+    deps = [
+        "//proto/connections:offline_wire_formats_proto",
+    ],
+)

cpp/platform/impl/ios/Source/Mediums/GNCLeaks.h

@@ -0,0 +1,18 @@
+// Copyright 2020 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.
+
+#import <Foundation/Foundation.h>
+
+// Verifies that an object has been deallocated after the given time period.
+void GNCVerifyDealloc(id object, NSTimeInterval timeInterval);

cpp/platform/impl/ios/Source/Mediums/GNCLeaks.m

@@ -0,0 +1,27 @@
+// Copyright 2020 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.
+
+#import "third_party/nearby_connections/cpp/platform/impl/ios/Source/Mediums/GNCLeaks.h"
+
+void GNCVerifyDealloc(id object, NSTimeInterval timeInterval) {
+#if DEBUG
+  __weak id weakObj = object;
+  NSCAssert(weakObj != nil, @"Pointer to %@ is already nil", weakObj);
+  NSLog(@"Verifying deallocation of %@", NSStringFromClass([weakObj class]));
+  dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(timeInterval * NSEC_PER_SEC)),
+                 dispatch_get_main_queue(), ^{
+                   NSCAssert(weakObj == nil, @"%@ not deallocated.", weakObj);
+                 });
+#endif
+}

cpp/platform/impl/ios/Source/Mediums/GNCMConnection.h

@@ -0,0 +1,101 @@
+// Copyright 2020 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.
+
+#import <Foundation/Foundation.h>
+
+NS_ASSUME_NONNULL_BEGIN
+
+/** Result of a medium payload transfer. */
+typedef NS_ENUM(NSInteger, GNCMPayloadResult) {
+  GNCMPayloadResultSuccess,   // Payload delivery was successful.
+  GNCMPayloadResultFailure,   // An error occurred during payload delivery.
+  GNCMPayloadResultCanceled,  // Payload delivery was canceled.
+};
+
+/** Handler for a @c GNCMPayloadResult value. */
+typedef void (^GNCMPayloadResultHandler)(GNCMPayloadResult);
+
+/**
+ * A progress handler is periodically called during payload delivery. It is passed a value
+ * ranging from 0 (when the operation has just started) to the total size (when the operation is
+ * finished).
+ */
+typedef void (^GNCMProgressHandler)(size_t count);
+
+/** This handler is called when data is received from a remote endpoint. */
+typedef void (^GNCMPayloadHandler)(NSData *data);
+
+/**
+ * This represents a connection with a remote endpoint at the medium level. Use it to send
+ * payloads to the remote endpoint, and release it to disconnect.
+ */
+@protocol GNCMConnection <NSObject>
+
+/**
+ * Sends data to the remote endpoint. Wait for the completion to be called before sending another
+ * payload.
+ *
+ * @param payload         The data to send.
+ * @param progressHandler Called repeatedly for progress feedback while the data is being sent.
+ * @param completion      Callback called when the data has been fully sent,
+ *                        or it has failed to be sent (not connected or disconnected).
+ */
+- (void)sendData:(NSData *)payload
+    progressHandler:(GNCMProgressHandler)progressHandler
+         completion:(GNCMPayloadResultHandler)completion;
+
+@end
+
+/** This class contains optional handlers for a connection. */
+@interface GNCMConnectionHandlers : NSObject
+
+/** This handler is called when data is sent from the remote endpoint. */
+@property(nonatomic) GNCMPayloadHandler payloadHandler;
+
+/** This handler is called when the connection is ended. */
+@property(nonatomic) dispatch_block_t disconnectedHandler;
+
+/** This method creates a GNCMConnectionHandlers object from payload and disconnect handlers. */
++ (instancetype)payloadHandler:(GNCMPayloadHandler)payloadHandler
+           disconnectedHandler:(dispatch_block_t)disconnectedHandler;
+
+@end
+
+/**
+ * This handler takes a GNCMConnection object and returns a GNCMConnectionHandlers object. It is
+ * called when a connection is successfully made with a remote endpoint. If |connection| is nil,
+ * the connection couldn't be established; in this case, return nil.
+ */
+typedef GNCMConnectionHandlers *_Nullable (^GNCMConnectionHandler)(
+    id<GNCMConnection> __nullable connection);
+
+/**
+ * This handler is called by a discovering endpoint to request a connection with an an advertising
+ * endpoint.
+ */
+typedef void (^GNCMConnectionRequester)(GNCMConnectionHandler connectionHandler);
+
+/** This handler is called when a previously discovered advertising endpoint is lost. */
+typedef void (^GNCMEndpointLostHandler)(void);
+
+/**
+ * This handler is called on a discoverer when a nearby advertising endpoint is
+ * discovered. Calls |requestConnection| to request a connection with the advertiser.
+ */
+typedef GNCMEndpointLostHandler _Nonnull (^GNCMEndpointFoundHandler)(
+    NSString *endpointId, NSString *serviceType, NSString *serviceName,
+    NSDictionary<NSString *, NSData *> *_Nullable TXTRecordData,
+    GNCMConnectionRequester requestConnection);
+
+NS_ASSUME_NONNULL_END

cpp/platform/impl/ios/Source/Mediums/GNCMConnection.m

@@ -0,0 +1,31 @@
+// Copyright 2020 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.
+
+#import "third_party/nearby_connections/cpp/platform/impl/ios/Source/Mediums/GNCMConnection.h"
+
+NS_ASSUME_NONNULL_BEGIN
+
+@implementation GNCMConnectionHandlers
+
++ (instancetype)payloadHandler:(GNCMPayloadHandler)payloadHandler
+           disconnectedHandler:(dispatch_block_t)disconnectedHandler {
+  GNCMConnectionHandlers *handlers = [[GNCMConnectionHandlers alloc] init];
+  handlers.payloadHandler = payloadHandler;
+  handlers.disconnectedHandler = disconnectedHandler;
+  return handlers;
+}
+
+@end
+
+NS_ASSUME_NONNULL_END

cpp/platform/impl/ios/Source/Mediums/WifiLan/GNCMBonjourBrowser.h

@@ -0,0 +1,42 @@
+// Copyright 2020 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.
+
+#import <Foundation/Foundation.h>
+
+#import "third_party/nearby_connections/cpp/platform/impl/ios/Source/Mediums/GNCMConnection.h"
+
+NS_ASSUME_NONNULL_BEGIN
+
+/**
+ * GNCMBonjourBrowser browses mDNS services publishing the specified mDNS type and domain. The mDNS
+ * type is a string formatted as "_[serviceIdHash]._tcp." in which [serviceIdHash] is generated as
+ * a SHA-256 hash from the service ID and taken the 6 first bytes of string in upper case.
+ * Calls the specififed endpoint found handler when one is found. The endpoint found handler
+ * supplies a requester block, which can be called to establish a socket to the service found.
+ *
+ * Don't hold the strong reference of caller self in endpointFoundHandler to ensure there is no
+ * retain cycle between them.
+ *
+ * @param serviceType An mDNS type that uniquely identifies the published service to search for.
+ * @param endpointFoundHandler The handler that is called when an endpoint publishing the service
+ *                             ID is discovered.
+ */
+@interface GNCMBonjourBrowser : NSObject
+
+- (instancetype)initWithServiceType:(NSString *)serviceType
+               endpointFoundHandler:(GNCMEndpointFoundHandler)handler;
+
+@end
+
+NS_ASSUME_NONNULL_END

cpp/platform/impl/ios/Source/Mediums/WifiLan/GNCMBonjourBrowser.m

@@ -0,0 +1,176 @@
+// Copyright 2020 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.
+
+#import "third_party/nearby_connections/cpp/platform/impl/ios/Source/Mediums/WifiLan/GNCMBonjourBrowser.h"
+
+#import "third_party/nearby_connections/cpp/platform/impl/ios/Source/Mediums/GNCMConnection.h"
+#import "third_party/nearby_connections/cpp/platform/impl/ios/Source/Mediums/WifiLan/GNCMBonjourConnection.h"
+#import "third_party/nearby_connections/cpp/platform/impl/ios/Source/Mediums/WifiLan/GNCMBonjourUtils.h"
+#import "third_party/objective_c/google_toolbox_for_mac/Foundation/GTMLogger.h"
+
+typedef NSString *GNCEndpointId;
+
+@interface GNCMNetServiceInfo : NSObject
+@property(nonatomic) NSNetService *service;
+@property(nonatomic, copy) GNCMEndpointLostHandler endpointLostHandler;
+@property(nonatomic, copy, nullable) GNCMConnectionHandler connectionHandler;
+@end
+
+@implementation GNCMNetServiceInfo
+
++ (instancetype)infoWithService:(NSNetService *)service {
+  GNCMNetServiceInfo *info = [[GNCMNetServiceInfo alloc] init];
+  info.service = service;
+  return info;
+}
+
+- (BOOL)isEqual:(GNCMNetServiceInfo *)object {
+  return [_service isEqual:object.service];
+}
+
+- (NSUInteger)hash {
+  return [_service hash];
+}
+
+@end
+
+@interface GNCMBonjourBrowser () <NSNetServiceBrowserDelegate, NSNetServiceDelegate>
+
+@property(nonatomic, copy) GNCMEndpointFoundHandler endpointFoundHandler;
+
+@property(nonatomic) NSNetServiceBrowser *netBrowser;
+@property(nonatomic) NSMutableDictionary<GNCEndpointId, GNCMNetServiceInfo *> *endpoints;
+
+@end
+
+@implementation GNCMBonjourBrowser
+
+- (instancetype)initWithServiceType:(NSString *)serviceType
+               endpointFoundHandler:(GNCMEndpointFoundHandler)handler {
+  self = [super init];
+  if (self) {
+    _endpointFoundHandler = handler;
+
+    _netBrowser = [[NSNetServiceBrowser alloc] init];
+    _netBrowser.delegate = self;
+    [_netBrowser scheduleInRunLoop:[NSRunLoop mainRunLoop] forMode:NSDefaultRunLoopMode];
+    [_netBrowser searchForServicesOfType:serviceType inDomain:GNCMBonjourDomain];
+    _endpoints = [NSMutableDictionary dictionary];
+  }
+  return self;
+}
+
+#pragma mark NSNetServiceBrowserDelegate
+
+- (void)netServiceBrowserWillSearch:(NSNetServiceBrowser *)browser {
+  GTMLoggerDebug(@"Browsing");
+}
+
+- (void)netServiceBrowserDidStopSearch:(NSNetServiceBrowser *)browser {
+  GTMLoggerDebug(@"Stop browsing");
+}
+
+- (void)netServiceBrowser:(NSNetServiceBrowser *)browser
+             didNotSearch:(NSDictionary<NSString *, NSNumber *> *)errorDict {
+  GTMLoggerDebug(@"Not browsing with errorDict: %@", errorDict);
+}
+
+- (void)netServiceBrowser:(NSNetServiceBrowser *)browser
+           didFindService:(NSNetService *)service
+               moreComing:(BOOL)moreComing {
+  GTMLoggerDebug(@"Found service: %@", service);
+
+  GNCMNetServiceInfo *info = [GNCMNetServiceInfo infoWithService:service];
+
+  // Just to be safe, check if the service is already known and deal with it accordingly.
+  NSArray<GNCEndpointId> *endpointIds = [_endpoints allKeysForObject:info];
+  if (endpointIds.count > 0) return;
+
+  // Add the newly discovered service to the list of services.
+  GNCEndpointId endpointId = [[NSUUID UUID] UUIDString];
+  _endpoints[endpointId] = info;
+
+  service.delegate = self;
+  [service resolveWithTimeout:0];
+}
+
+- (void)netServiceBrowser:(NSNetServiceBrowser *)browser
+         didRemoveService:(NSNetService *)service
+               moreComing:(BOOL)moreComing {
+  GTMLoggerDebug(@"Lost service: %@", service);
+  NSArray<GNCEndpointId> *endpointIds =
+      [_endpoints allKeysForObject:[GNCMNetServiceInfo infoWithService:service]];
+  NSAssert(endpointIds.count <= 1, @"Unexpected duplicate service");
+  if (endpointIds.count > 0) {
+    GNCEndpointId endpointId = endpointIds[0];
+    GNCMNetServiceInfo *info = _endpoints[endpointId];
+    [_endpoints removeObjectForKey:endpointId];
+    // Tail call to preserve reentrancy.
+    if (info.endpointLostHandler) {
+      info.endpointLostHandler();
+    }
+  }
+}
+
+#pragma mark NSNetServiceDelegate
+
+- (void)netServiceDidResolveAddress:(NSNetService *)service {
+  GTMLoggerDebug(@"Resolved service: %@ addresses: %@", service, service.addresses);
+
+  GNCMNetServiceInfo *info = [GNCMNetServiceInfo infoWithService:service];
+
+  NSArray<GNCEndpointId> *endpointIds = [_endpoints allKeysForObject:info];
+  if (endpointIds.count > 0) {
+    // Get TXTRecord data.
+    NSData *data = [service TXTRecordData];
+    NSDictionary<NSString *, NSData *> *TXTRecordData =
+        [NSNetService dictionaryFromTXTRecordData:data];
+
+    // The endpointLostHandler is returned from the endpointFoundHandler. The main benefit of this
+    // is that it allows rejection from the remote endpoint to be received by the local endpoint
+    // before the local endpoint has accepted or rejected.
+    info.endpointLostHandler = _endpointFoundHandler(
+        endpointIds[0], service.type, service.name, TXTRecordData,
+        ^(GNCMConnectionHandler connectionHandler) {
+          // A connection is requested, so resolve the service to get the I/O streams.
+          info.connectionHandler = connectionHandler;
+          if (info.connectionHandler) {
+            dispatch_sync(dispatch_get_main_queue(), ^{
+              NSInputStream *inputStream;
+              NSOutputStream *outputStream;
+              [info.service scheduleInRunLoop:[NSRunLoop mainRunLoop] forMode:NSDefaultRunLoopMode];
+              [info.service getInputStream:&inputStream outputStream:&outputStream];
+              GNCMBonjourConnection *connection =
+                  [[GNCMBonjourConnection alloc] initWithInputStream:inputStream
+                                                        outputStream:outputStream
+                                                               queue:nil];
+              connection.connectionHandlers = info.connectionHandler(connection);
+            });
+          }
+        });
+    _endpoints[endpointIds[0]] = info;
+  }
+}
+
+- (void)netService:(NSNetService *)service
+     didNotResolve:(NSDictionary<NSString *, NSNumber *> *)errorDict {
+  GTMLoggerDebug(@"Did not resolve service: %@", service);
+  NSArray<GNCEndpointId> *endpointIds =
+      [_endpoints allKeysForObject:[GNCMNetServiceInfo infoWithService:service]];
+  if (endpointIds.count > 0) {
+    _endpoints[endpointIds[0]].connectionHandler = nil;
+  }
+}
+
+@end

cpp/platform/impl/ios/Source/Mediums/WifiLan/GNCMBonjourConnection.h

@@ -0,0 +1,38 @@
+// Copyright 2020 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.
+
+#import <Foundation/Foundation.h>
+
+#import "third_party/nearby_connections/cpp/platform/impl/ios/Source/Mediums/GNCMConnection.h"
+
+NS_ASSUME_NONNULL_BEGIN
+
+/**
+ * This medium connection sends and receives payloads over the NSInputStream and NSOutputStream
+ * passed to it.
+ *
+ * @param inputStream The input stream to read from.
+ * @param outputStream The output stream to write to.
+ * @param queue The queue on which the GNCMConnection callbacks will be called. If nil, the main
+ *              queue is used.
+ */
+@interface GNCMBonjourConnection : NSObject <GNCMConnection>
+@property(nonatomic) GNCMConnectionHandlers *connectionHandlers;
+
+- (instancetype)initWithInputStream:(NSInputStream *)inputStream
+                       outputStream:(NSOutputStream *)outputStream
+                              queue:(nullable dispatch_queue_t)queue;
+@end
+
+NS_ASSUME_NONNULL_END

cpp/platform/impl/ios/Source/Mediums/WifiLan/GNCMBonjourConnection.m

@@ -0,0 +1,207 @@
+// Copyright 2020 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.
+
+#import "third_party/nearby_connections/cpp/platform/impl/ios/Source/Mediums/WifiLan/GNCMBonjourConnection.h"
+
+#import "third_party/nearby_connections/cpp/platform/impl/ios/Source/Mediums/GNCMConnection.h"
+#import "third_party/objective_c/google_toolbox_for_mac/Foundation/GTMLogger.h"
+
+enum { kMaxPacketSize = 32 * 1024 };
+
+@interface GNCMBonjourConnection () <NSStreamDelegate>
+@property(nonatomic) NSInputStream *inputStream;
+@property(nonatomic) NSOutputStream *outputStream;
+@property(nonatomic) dispatch_queue_t callbackQueue;
+
+@property(nonatomic, copy, nullable) NSData *dataBeingWritten;
+@property(nonatomic) NSInteger numberOfBytesLeftToWrite;
+@property(nonatomic, copy, nullable) GNCMProgressHandler progressHandler;
+@property(nonatomic, copy, nullable) GNCMPayloadResultHandler completion;
+@end
+
+@implementation GNCMBonjourConnection
+
+- (instancetype)initWithInputStream:(NSInputStream *)inputStream
+                       outputStream:(NSOutputStream *)outputStream
+                              queue:(nullable dispatch_queue_t)queue {
+  self = [super init];
+  if (self) {
+    _inputStream = inputStream;
+    _inputStream.delegate = self;
+    [_inputStream scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
+    [_inputStream open];
+
+    _outputStream = outputStream;
+    _outputStream.delegate = self;
+    [_outputStream scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
+    [_outputStream open];
+
+    _callbackQueue = queue;
+  }
+  return self;
+}
+
+- (void)dealloc {
+  [self closeStreams];
+}
+
+- (void)sendData:(NSData *)payload
+    progressHandler:(GNCMProgressHandler)progressHandler
+         completion:(GNCMPayloadResultHandler)completion {
+  if (_dataBeingWritten) {
+    GTMLoggerInfo(@"Attempting to send payload while one is already in flight");
+    [self dispatchCallback:^{
+      completion(GNCMPayloadResultFailure);
+    }];
+    return;
+  }
+
+  self.dataBeingWritten = payload;
+  self.numberOfBytesLeftToWrite = payload.length;
+  self.progressHandler = progressHandler;
+  self.completion = completion;
+  [self writeChunk];
+}
+
+#pragma mark NSStreamDelegate
+
+- (void)stream:(NSStream *)stream handleEvent:(NSStreamEvent)event {
+  switch (event) {
+    case NSStreamEventHasBytesAvailable: {
+      // Data has arrived on the input stream.
+      NSAssert(stream == _inputStream, @"Error: Expected input stream");
+
+      if (_connectionHandlers.payloadHandler) {
+        uint8_t bytesRead[kMaxPacketSize];
+        NSInteger numberOfBytesRead;
+        @synchronized(self.inputStream) {
+          numberOfBytesRead = [self.inputStream read:bytesRead maxLength:kMaxPacketSize];
+        }
+        NSData *data = nil;
+        if (numberOfBytesRead > 0) {
+          GTMLoggerInfo(@"Read %lu bytes", (u_long)numberOfBytesRead);
+          data = [NSData dataWithBytes:bytesRead length:numberOfBytesRead];
+        }
+        [self dispatchCallback:^{
+          self.connectionHandlers.payloadHandler(data ?: [NSData data]);
+        }];
+      }
+      break;
+    }
+
+    case NSStreamEventHasSpaceAvailable:
+      // There is space available on the output stream.
+      NSAssert(stream == _outputStream, @"Error: Expected output stream");
+
+      // Schedule this in a future runloop cycle because -writeChunk, which can cause this event
+      // to be received synchronously, is not reentrant.
+      [self performSelector:@selector(writeChunk) withObject:nil afterDelay:0.0];
+      break;
+
+    case NSStreamEventErrorOccurred:
+      GTMLoggerInfo(@"Stream error: %@", [stream streamError]);
+      // Fall through.
+    case NSStreamEventEndEncountered: {
+      GTMLoggerInfo(@"Stream closing");
+      [self closeStreams];
+      if (_connectionHandlers.disconnectedHandler) {
+        [self dispatchCallback:^{
+          self.connectionHandlers.disconnectedHandler();
+        }];
+      }
+      break;
+    }
+
+    case NSStreamEventOpenCompleted:
+    case NSStreamEventNone:
+    default:
+      break;
+  }
+}
+
+#pragma mark Private
+
+// Calls a block on the callback queue.
+- (void)dispatchCallback:(dispatch_block_t)block {
+  dispatch_async(_callbackQueue ?: dispatch_get_main_queue(), block);
+}
+
+// Writes a chunk of the outgoing data to the output stream, calling the progress and completion
+// handlers as needed.
+- (void)writeChunk {
+  void (^reportProgress)(size_t) = ^(size_t count) {
+    // Captures the progress handler because the property is nilled out below.
+    GNCMProgressHandler progressHandler = _progressHandler;
+    if (progressHandler != nil) {
+      [self dispatchCallback:^{
+        progressHandler(count);
+      }];
+    }
+  };
+
+  void (^completed)(GNCMPayloadResult) = ^(GNCMPayloadResult result) {
+    reportProgress(_dataBeingWritten.length);
+    _progressHandler = nil;
+    _dataBeingWritten = nil;
+
+    // Captures the completion because the property is nilled out below.
+    GNCMPayloadResultHandler completion = _completion;
+    if (completion != nil) {
+      [self dispatchCallback:^{
+        completion(result);
+      }];
+    }
+    _completion = nil;
+  };
+
+  @synchronized(_outputStream) {
+    if (_numberOfBytesLeftToWrite) {
+      NSUInteger dataLength = (UInt32)_dataBeingWritten.length;
+      if (_numberOfBytesLeftToWrite == dataLength) {
+        GTMLoggerInfo(@"Starting a write operation of length %lu", (u_long)dataLength);
+      }
+      NSInteger numberOfPayloadBytesWritten =
+          [_outputStream write:&_dataBeingWritten.bytes[dataLength - _numberOfBytesLeftToWrite]
+                     maxLength:_numberOfBytesLeftToWrite];
+
+      GTMLoggerInfo(@"Wrote %lu bytes", (u_long)numberOfPayloadBytesWritten);
+      if (numberOfPayloadBytesWritten >= 0) {
+        _numberOfBytesLeftToWrite -= numberOfPayloadBytesWritten;
+        reportProgress(_dataBeingWritten.length - _numberOfBytesLeftToWrite);
+        if (_numberOfBytesLeftToWrite < 0) {
+          GTMLoggerInfo(@"Unexpected number of bytes written");
+          _numberOfBytesLeftToWrite = 0;
+        }
+        if (_numberOfBytesLeftToWrite == 0) completed(GNCMPayloadResultSuccess);
+      } else {
+        GTMLoggerInfo(@"Error writing to output stream");
+        completed(GNCMPayloadResultFailure);
+      }
+    }
+  }
+}
+
+- (void)closeStreams {
+  @synchronized(_inputStream) {
+    [_inputStream close];
+    _inputStream = nil;
+  }
+
+  @synchronized(_outputStream) {
+    [_outputStream close];
+    _outputStream = nil;
+  }
+}
+
+@end

cpp/platform/impl/ios/Source/Mediums/WifiLan/GNCMBonjourService.h

@@ -0,0 +1,49 @@
+// Copyright 2020 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.
+
+#import <Foundation/Foundation.h>
+#import <UIKit/UIKit.h>
+
+#import "third_party/nearby_connections/cpp/platform/impl/ios/Source/Mediums/GNCMConnection.h"
+
+NS_ASSUME_NONNULL_BEGIN
+
+/**
+ * GNCMBonjourService publishes mDNS type and domain with the specified service ID via Apple
+ * Bonjour service. The mDNS type is a string formatted as "_[serviceIdHash]._tcp." in which
+ * [serviceIdHash] is generated as a SHA-256 hash from the service ID and taken the 6 first bytes
+ * of string in upper case.
+ * When the service connects, the specified |endpointConnectedHandler| is called, which establishes
+ * a connection to the browser.
+ *
+ * Don't hold the strong reference of caller self in endpointConnectedHandler to ensure there is no
+ * retain cycle between them.
+ *
+ * @param serviceName A service name that embeds the |WifiLanServiceInfo| information.
+ * @param serviceType An mDNS type that uniquely identifies the published service to search for.
+ * @param port The requesting socket port number.
+ * @param txtRecordData The TXTRecord data.
+ * @param endpointConnectedHandler The handler that is called when a browser connects.
+ */
+@interface GNCMBonjourService : NSObject
+
+- (instancetype)initWithServiceName:(NSString *)serviceName
+                        serviceType:(NSString *)serviceType
+                               port:(NSInteger)port
+                      TXTRecordData:(NSDictionary<NSString *, NSData *> *)TXTRecordData
+           endpointConnectedHandler:(GNCMConnectionHandler)handler;
+
+@end
+
+NS_ASSUME_NONNULL_END

cpp/platform/impl/ios/Source/Mediums/WifiLan/GNCMBonjourService.m

@@ -0,0 +1,88 @@
+// Copyright 2020 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.
+
+#import "third_party/nearby_connections/cpp/platform/impl/ios/Source/Mediums/WifiLan/GNCMBonjourService.h"
+
+#import "third_party/nearby_connections/cpp/platform/impl/ios/Source/Mediums/GNCMConnection.h"
+#import "third_party/nearby_connections/cpp/platform/impl/ios/Source/Mediums/WifiLan/GNCMBonjourConnection.h"
+#import "third_party/nearby_connections/cpp/platform/impl/ios/Source/Mediums/WifiLan/GNCMBonjourUtils.h"
+#import "third_party/objective_c/google_toolbox_for_mac/Foundation/GTMLogger.h"
+
+@interface GNCMBonjourService () <NSNetServiceDelegate>
+
+@property(nonatomic, copy) NSString *serviceName;
+@property(nonatomic, copy) NSString *serviceType;
+@property(nonatomic, copy) GNCMConnectionHandler endpointConnectedHandler;
+
+@property(nonatomic) NSNetService *netService;
+
+@end
+
+@implementation GNCMBonjourService
+
+- (instancetype)initWithServiceName:(NSString *)serviceName
+                        serviceType:(NSString *)serviceType
+                               port:(NSInteger)port
+                      TXTRecordData:(NSDictionary<NSString *, NSData *> *)TXTRecordData
+           endpointConnectedHandler:(GNCMConnectionHandler)handler {
+  self = [super init];
+  if (self) {
+    _serviceName = [serviceName copy];
+    _serviceType = [serviceType copy];
+    _endpointConnectedHandler = handler;
+
+    _netService = [[NSNetService alloc] initWithDomain:GNCMBonjourDomain
+                                                  type:_serviceType
+                                                  name:_serviceName
+                                                  port:port];
+    [_netService setTXTRecordData:[NSNetService dataFromTXTRecordDictionary:TXTRecordData]];
+
+    _netService.delegate = self;
+    [_netService scheduleInRunLoop:[NSRunLoop mainRunLoop] forMode:NSDefaultRunLoopMode];
+    [_netService publishWithOptions:NSNetServiceListenForConnections];
+  }
+  return self;
+}
+
+- (void)dealloc {
+  [_netService stop];
+}
+
+#pragma mark NSNetServiceDelegate
+
+- (void)netServiceDidPublish:(NSNetService *)service {
+  GTMLoggerDebug(@"Did publish service: %@", service);
+}
+
+- (void)netService:(NSNetService *)service
+     didNotPublish:(NSDictionary<NSString *, NSNumber *> *)errorDict {
+  GTMLoggerDebug(@"Error publishing: service: %@, errorDic: %@", service, errorDict);
+}
+
+- (void)netServiceDidStop:(NSNetService *)service {
+  GTMLoggerDebug(@"Stopped publishing service: %@", service);
+}
+
+- (void)netService:(NSNetService *)service
+    didAcceptConnectionWithInputStream:(NSInputStream *)inputStream
+                          outputStream:(NSOutputStream *)outputStream {
+  GTMLoggerDebug(@"Accepted connection, service: %@", service);
+  GNCMBonjourConnection *connection =
+      [[GNCMBonjourConnection alloc] initWithInputStream:inputStream
+                                            outputStream:outputStream
+                                                   queue:nil];
+  connection.connectionHandlers = _endpointConnectedHandler(connection);
+}
+
+@end

cpp/platform/impl/ios/Source/Mediums/WifiLan/GNCMBonjourUtils.h

@@ -0,0 +1,18 @@
+// Copyright 2020 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.
+
+#import <Foundation/Foundation.h>
+
+// mDNS domain.
+FOUNDATION_EXPORT NSString *_Nonnull const GNCMBonjourDomain;

cpp/platform/impl/ios/Source/Mediums/WifiLan/GNCMBonjourUtils.m

@@ -0,0 +1,17 @@
+// Copyright 2020 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.
+
+#import "third_party/nearby_connections/cpp/platform/impl/ios/Source/Mediums/WifiLan/GNCMBonjourUtils.h"
+
+NSString *const GNCMBonjourDomain = @"local";