Communication protocol for Dive: Messages

- Messages (Request/Response) were added for the socket connection.
- Helper functions for messages were added.

Author: elviscapiaq

network/CMakeLists.txt

@@ -18,9 +18,9 @@ cmake_minimum_required(VERSION 3.10 FATAL_ERROR)
 
 project(network)
 
-set(NETWORK_SRCS socket_connection.cc)
+set(NETWORK_SRCS socket_connection.cc messages.cc)
 
-set(NETWORK_HDRS socket_connection.h)
+set(NETWORK_HDRS socket_connection.h serializable.h messages.h)
 
 add_library(network SHARED ${NETWORK_SRCS} ${NETWORK_HDRS})
 

network/messages.cc

@@ -0,0 +1,334 @@
+/*
+Copyright 2025 Google Inc.
+
+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
+
+http://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 "messages.h"
+
+#ifdef WIN32
+#    include <winsock2.h>
+#else
+#    include <netinet/in.h>
+#endif
+
+namespace Network
+{
+
+void WriteUint32ToBuffer(uint32_t value, Buffer& dest)
+{
+    uint32_t       net_val = htonl(value);
+    const uint8_t* p_val = reinterpret_cast<const uint8_t*>(&net_val);
+    dest.insert(dest.end(), p_val, p_val + sizeof(uint32_t));
+}
+
+void WriteStringToBuffer(const std::string& str, Buffer& dest)
+{
+    WriteUint32ToBuffer(static_cast<uint32_t>(str.length()), dest);
+    dest.insert(dest.end(), str.begin(), str.end());
+}
+
+absl::StatusOr<uint32_t> ReadUint32FromBuffer(const Buffer& src, size_t& offset)
+{
+    if (src.size() < offset + sizeof(uint32_t))
+    {
+        return absl::InvalidArgumentError("Buffer too small to read a uint32_t.");
+    }
+    uint32_t net_val;
+    std::memcpy(&net_val, src.data() + offset, sizeof(uint32_t));
+    offset += sizeof(uint32_t);
+    return ntohl(net_val);
+}
+
+absl::StatusOr<std::string> ReadStringFromBuffer(const Buffer& src, size_t& offset)
+{
+    absl::StatusOr<uint32_t> len_or = ReadUint32FromBuffer(src, offset);
+    if (!len_or.ok())
+    {
+        return len_or.status();
+    }
+
+    uint32_t len = len_or.value();
+    if (src.size() < offset + len)
+    {
+        return absl::InvalidArgumentError("Buffer too small for declared string length.");
+    }
+    std::string result(reinterpret_cast<const char*>(src.data() + offset), len);
+    offset += len;
+    return result;
+}
+
+absl::Status HandShakeMessage::Serialize(Buffer& dest) const
+{
+    dest.clear();
+    WriteUint32ToBuffer(major_version, dest);
+    WriteUint32ToBuffer(minor_version, dest);
+    return absl::OkStatus();
+}
+
+absl::Status HandShakeMessage::Deserialize(const Buffer& src)
+{
+    size_t                   offset = 0;
+    absl::StatusOr<uint32_t> major_or = ReadUint32FromBuffer(src, offset);
+    if (!major_or.ok())
+    {
+        return major_or.status();
+    }
+    major_version = major_or.value();
+
+    absl::StatusOr<uint32_t> minor_or = ReadUint32FromBuffer(src, offset);
+    if (!minor_or.ok())
+    {
+        return minor_or.status();
+    }
+    minor_version = minor_or.value();
+
+    if (offset != src.size())
+    {
+        return absl::InvalidArgumentError("Handshake message has unexpected trailing data.");
+    }
+    return absl::OkStatus();
+}
+
+absl::Status StringMessage::Serialize(Buffer& dest) const
+{
+    dest.clear();
+    WriteStringToBuffer(str, dest);
+    return absl::OkStatus();
+}
+
+absl::Status StringMessage::Deserialize(const Buffer& src)
+{
+    size_t                      offset = 0;
+    absl::StatusOr<std::string> str_or = ReadStringFromBuffer(src, offset);
+    if (!str_or.ok())
+    {
+        return str_or.status();
+    }
+
+    str = std::move(str_or.value());
+    if (offset != src.size())
+    {
+        return absl::InvalidArgumentError("String message has unexpected trailing data.");
+    }
+    return absl::OkStatus();
+}
+
+absl::Status DownloadFileResponse::Serialize(Buffer& dest) const
+{
+    dest.push_back(static_cast<uint8_t>(found));
+    WriteStringToBuffer(error_reason, dest);
+    WriteStringToBuffer(file_path, dest);
+    WriteStringToBuffer(file_size_str, dest);
+
+    return absl::OkStatus();
+}
+
+absl::Status DownloadFileResponse::Deserialize(const Buffer& src)
+{
+    size_t offset = 0;
+
+    // Deserialize the 'found' boolean.
+    if (src.size() < offset + sizeof(uint8_t))
+    {
+        return absl::InvalidArgumentError("Buffer too small for 'found' field.");
+    }
+    found = (src[offset] != 0);
+    offset += sizeof(uint8_t);
+
+    // Deserialize the strings using the StatusOr-returning helper
+    absl::StatusOr<std::string> error_reason_or = ReadStringFromBuffer(src, offset);
+    if (!error_reason_or.ok())
+    {
+        return error_reason_or.status();  // Forward the error
+    }
+    error_reason = std::move(error_reason_or.value());
+
+    absl::StatusOr<std::string> file_path_or = ReadStringFromBuffer(src, offset);
+    if (!file_path_or.ok())
+    {
+        return file_path_or.status();
+    }
+    file_path = std::move(file_path_or.value());
+
+    absl::StatusOr<std::string> file_size_or = ReadStringFromBuffer(src, offset);
+    if (!file_size_or.ok())
+    {
+        return file_size_or.status();
+    }
+    file_size_str = std::move(file_size_or.value());
+
+    // Final check for trailing data.
+    if (offset != src.size())
+    {
+        return absl::InvalidArgumentError("Message has unexpected trailing data.");
+    }
+
+    return absl::OkStatus();
+}
+
+absl::Status ReceiveFull(SocketConnection* conn, uint8_t* buffer, size_t size)
+{
+    if (!conn)
+    {
+        return absl::InvalidArgumentError("Provided SocketConnection is null.");
+    }
+    size_t total_received = 0;
+    while (total_received < size)
+    {
+        absl::StatusOr<size_t> received_or = conn->Recv(buffer + total_received,
+                                                        size - total_received);
+        if (!received_or.ok())
+        {
+            return received_or.status();
+        }
+        total_received += received_or.value();
+    }
+    return absl::OkStatus();
+}
+
+absl::Status SendFull(SocketConnection* conn, const uint8_t* buffer, size_t size)
+{
+    if (!conn)
+    {
+        return absl::InvalidArgumentError("Provided SocketConnection is null.");
+    }
+    return conn->Send(buffer, size);
+}
+
+absl::StatusOr<std::unique_ptr<ISerializable>> ReceiveMessage(SocketConnection* conn)
+{
+    if (!conn)
+    {
+        return absl::InvalidArgumentError("Provided SocketConnection is null.");
+    }
+
+    const size_t header_size = sizeof(uint32_t) * 2;
+    uint8_t      header_buffer[header_size];
+
+    // Receive the message header.
+    absl::Status status = ReceiveFull(conn, header_buffer, header_size);
+    if (!status.ok())
+    {
+        return status;
+    }
+
+    // Parse header.
+    uint32_t net_type, net_length;
+    std::memcpy(&net_type, header_buffer, sizeof(uint32_t));
+    std::memcpy(&net_length, header_buffer + sizeof(uint32_t), sizeof(uint32_t));
+    uint32_t type = ntohl(net_type);
+    uint32_t payload_length = ntohl(net_length);
+
+    if (payload_length > kMaxPayloadSize)
+    {
+        conn->Close();
+        return absl::InvalidArgumentError(
+        absl::StrCat("Payload size ", payload_length, " exceeds limit."));
+    }
+
+    // Receive the message payload.
+    Buffer payload_buffer(payload_length);
+    status = ReceiveFull(conn, payload_buffer.data(), payload_length);
+    if (!status.ok())
+    {
+        return status;
+    }
+
+    // Create and deserialize the message object.
+    std::unique_ptr<ISerializable> message;
+    switch (static_cast<MessageType>(type))
+    {
+    case MessageType::HANDSHAKE_REQUEST:
+        message = std::make_unique<HandShakeRequest>();
+        break;
+    case MessageType::HANDSHAKE_RESPONSE:
+        message = std::make_unique<HandShakeResponse>();
+        break;
+    case MessageType::PING_MESSAGE:
+        message = std::make_unique<PingMessage>();
+        break;
+    case MessageType::PONG_MESSAGE:
+        message = std::make_unique<PongMessage>();
+        break;
+    case MessageType::CAPTURE_REQUEST:
+        message = std::make_unique<CaptureRequest>();
+        break;
+    case MessageType::CAPTURE_RESPONSE:
+        message = std::make_unique<CaptureResponse>();
+        break;
+    case MessageType::DOWNLOAD_FILE_REQUEST:
+        message = std::make_unique<DownloadFileRequest>();
+        break;
+    case MessageType::DOWNLOAD_FILE_RESPONSE:
+        message = std::make_unique<DownloadFileResponse>();
+        break;
+    default:
+        conn->Close();
+        return absl::InvalidArgumentError(absl::StrCat("Unknown message type: ", type));
+    }
+
+    status = message->Deserialize(payload_buffer);
+    if (!status.ok())
+    {
+        conn->Close();
+        return status;
+    }
+
+    return message;
+}
+
+absl::Status SendMessage(SocketConnection* conn, const ISerializable& message)
+{
+    if (!conn)
+    {
+        return absl::InvalidArgumentError("Provided SocketConnection is null.");
+    }
+
+    // Serialize the message payload.
+    Buffer       payload_buffer;
+    absl::Status status = message.Serialize(payload_buffer);
+    if (!status.ok())
+    {
+        return status;
+    }
+    if (payload_buffer.size() > kMaxPayloadSize)
+    {
+        return absl::InvalidArgumentError("Serialized payload size exceeds limit.");
+    }
+
+    // Construct and send the header.
+    uint32_t     net_type = htonl(message.GetMessageType());
+    uint32_t     net_payload_length = htonl(static_cast<uint32_t>(payload_buffer.size()));
+    const size_t header_size = sizeof(net_type) + sizeof(net_payload_length);
+    uint8_t      header_buffer[header_size];
+    std::memcpy(header_buffer, &net_type, sizeof(uint32_t));
+    std::memcpy(header_buffer + sizeof(uint32_t), &net_payload_length, sizeof(uint32_t));
+
+    status = SendFull(conn, header_buffer, header_size);
+    if (!status.ok())
+    {
+        return status;
+    }
+
+    // Send the payload.
+    status = SendFull(conn, payload_buffer.data(), payload_buffer.size());
+    if (!status.ok())
+    {
+        return status;
+    }
+
+    return absl::OkStatus();
+}
+
+}  // namespace Network