Add OpenL2capServerSocket and skeleton BleL2capServerSocket/BleL2capSocket

PiperOrigin-RevId: 746334743

internal/platform/implementation/apple/ble_l2cap_socket.h

@@ -0,0 +1,122 @@
+// Copyright 2025 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 <memory>
+
+#import "internal/platform/implementation/apple/Mediums/BLEv2/GNCBLEL2CAPStream.h"
+#import "internal/platform/implementation/apple/ble_peripheral.h"
+#include "internal/platform/implementation/ble_v2.h"
+
+namespace nearby {
+namespace apple {
+
+/** A readable stream of bytes. */
+class BleL2capInputStream : public InputStream {
+ public:
+  // Creates a BleL2capInputStream.
+  //
+  // @param stream The underlying stream to use for reading and writing.
+  explicit BleL2capInputStream(GNCBLEL2CAPStream* stream);
+  ~BleL2capInputStream() override = default;
+
+  // Reads at most `size` bytes from the input stream.
+  //
+  // Returns an empty byte array on end of file, or Exception::kIo on error.
+  ExceptionOr<ByteArray> Read(std::int64_t size) override;
+
+  // Closes the stream preventing further reads.
+  //
+  // Returns Exception::kIo on error, otherwise Exception::kSuccess.
+  Exception Close() override;
+
+ private:
+  GNCBLEL2CAPStream* stream_;
+};
+
+/** A writable stream of bytes. */
+class BleL2capOutputStream : public OutputStream {
+ public:
+  // Creates a BleL2capOutputStream.
+  //
+  // @param stream The underlying stream to use for reading and writing.
+  explicit BleL2capOutputStream(GNCBLEL2CAPStream* stream);
+  ~BleL2capOutputStream() override = default;
+
+  // Write the provided bytes to the output stream.
+  //
+  // Returns Exception::kIo on error, otherwise Exception::kSuccess.
+  Exception Write(const ByteArray& data) override;
+
+  // no-op
+  //
+  // Always returns Exception::kSuccess.
+  Exception Flush() override;
+
+  // Closes the stream preventing further writes.
+  //
+  // Returns Exception::kIo on error, otherwise Exception::kSuccess.
+  Exception Close() override;
+
+ private:
+  GNCBLEL2CAPStream* stream_;
+};
+
+/**
+ * Concrete BleL2capSocket implementation.
+ */
+class BleL2capSocket : public api::ble_v2::BleL2capSocket {
+ public:
+  explicit BleL2capSocket(GNCBLEL2CAPStream* stream);
+
+  // The peripheral used to create the socket must outlive the socket or
+  // undefined behavior will occur.
+  BleL2capSocket(GNCBLEL2CAPStream* stream,
+                 api::ble_v2::BlePeripheral* peripheral);
+  ~BleL2capSocket() override = default;
+
+  // Returns the InputStream of the BleL2capSocket.
+  // On error, returned stream will report Exception::kIo on any operation.
+  //
+  // The returned object is not owned by the caller, and can be invalidated once
+  // the BleL2capSocket object is destroyed.
+  InputStream& GetInputStream() override;
+
+  // Returns the OutputStream of the BleL2capSocket.
+  // On error, returned stream will report Exception::kIo on any operation.
+  //
+  // The returned object is not owned by the caller, and can be invalidated once
+  // the BleL2capSocket object is destroyed.
+  OutputStream& GetOutputStream() override;
+
+  // Returns Exception::kIo on error, Exception::kSuccess otherwise.
+  Exception Close() override;
+
+  // Sets the close notifier by client side.
+  void SetCloseNotifier(absl::AnyInvocable<void()> notifier) override;
+
+  // Returns valid BlePeripheral pointer if there is a connection, and
+  // nullptr otherwise.
+  api::ble_v2::BlePeripheral* GetRemotePeripheral() override {
+    return peripheral_;
+  }
+
+ private:
+  GNCBLEL2CAPStream* stream_;
+  std::unique_ptr<BleL2capInputStream> input_stream_;
+  std::unique_ptr<BleL2capOutputStream> output_stream_;
+  api::ble_v2::BlePeripheral* peripheral_;
+};
+
+}  // namespace apple
+}  // namespace nearby