fix: resolve protobuf message parsing in CoreDeviceAdapter for v0.4.0 compatibility

[tylerkron]

User description

Summary

• Resolves issue CoreDeviceAdapter v0.4.0: LineBasedMessageParser incompatible with protobuf binary messages #35 where CoreDeviceAdapter v0.4.0 cannot parse binary protobuf messages sent by DAQiFi devices
• Enables Phase 2 integration of CoreDeviceAdapter in daqifi-desktop application
• Maintains full backward compatibility with existing SCPI text-based communication

Changes Made

🆕 New Message Parsers

• ProtobufMessageParser: Handles binary protobuf messages containing null bytes that caused the original LineBasedMessageParser to fail
• CompositeMessageParser: Intelligently routes between text and binary message parsers based on message content detection

🔧 Updated CoreDeviceAdapter

• Added configurable message parser constructor parameter with CompositeMessageParser default
• Updated event signatures to handle both string and DaqifiOutMessage types
• Added convenience factory methods for different communication scenarios:
  • CreateTcpAdapter() - Default composite parser (handles both text and protobuf)
  • CreateTextOnlyTcpAdapter() - Text-only for legacy SCPI communication
  • CreateProtobufOnlyTcpAdapter() - Protobuf-only for pure binary communication

📝 Updated Examples and Tests

• Modified DesktopIntegrationExample to demonstrate proper handling of both message types
• Updated CoreDeviceAdapterTests to work with new object-based message events

Impact

✅ Fixes: "MessageReceived events never fire" for protobuf responses
✅ Enables: Phase 2 integration in daqifi-desktop v0.4.1
✅ Maintains: Full backward compatibility with existing desktop applications
✅ Provides: Flexible configuration for different communication protocols

Usage Examples

Default Usage (Recommended)

// Automatically handles both text SCPI and binary protobuf messages
var adapter = CoreDeviceAdapter.CreateTcpAdapter("192.168.1.100", 12345);
adapter.MessageReceived += (sender, args) => {
    if (args.Message.Data is DaqifiOutMessage protobuf) {
        // Handle binary protobuf message
        ProcessProtobufMessage(protobuf);
    } else if (args.Message.Data is string text) {
        // Handle SCPI text response
        ProcessTextResponse(text);
    }
};

Custom Parser Configuration

var customParser = new CompositeMessageParser(
    new LineBasedMessageParser(), 
    new ProtobufMessageParser()
);
var adapter = new CoreDeviceAdapter(transport, customParser);

Test plan

• Build succeeds without errors
• All existing tests pass
• CompositeMessageParser correctly routes text and binary messages
• CoreDeviceAdapter maintains backward compatibility
• Factory methods create adapters with correct parser configurations
• Integration test with actual DAQiFi device (requires hardware)

Closes #35

🤖 Generated with Claude Code

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PR Type

Bug fix, Enhancement

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Description

• Fix protobuf message parsing in CoreDeviceAdapter for v0.4.0 compatibility

• Add CompositeMessageParser to handle both text and binary messages

• Update event signatures to support object-based message types

• Add factory methods for different communication scenarios

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Diagram Walkthrough

flowchart LR
  A["Raw Data"] --> B["CompositeMessageParser"]
  B --> C["Text Parser"]
  B --> D["Protobuf Parser"]
  C --> E["String Messages"]
  D --> F["DaqifiOutMessage"]
  E --> G["CoreDeviceAdapter Events"]
  F --> G

Loading

File Walkthrough

	Relevant files
Enhancement	CompositeMessageParser.cs Add composite message parser for dual protocol support      src/Daqifi.Core/Communication/Consumers/CompositeMessageParser.cs New composite parser that routes between text and protobuf parsers Detects message type based on null byte presence Returns ObjectInboundMessage wrapper for unified handling +117/-0  ProtobufMessageParser.cs Add protobuf message parser for binary data                            src/Daqifi.Core/Communication/Consumers/ProtobufMessageParser.cs New parser specifically for binary protobuf messages Handles variable-length protobuf message boundaries Includes error handling for invalid protocol buffer exceptions +59/-0
Bug fix	CoreDeviceAdapter.cs Update CoreDeviceAdapter to support multiple message types src/Daqifi.Core/Integration/Desktop/CoreDeviceAdapter.cs Add configurable message parser constructor parameter Update event signatures from string to object types Add factory methods for text-only and protobuf-only adapters Default to CompositeMessageParser for backward compatibility +40/-9
Documentation	DesktopIntegrationExample.cs Update examples for new message handling patterns                src/Daqifi.Core/Integration/Desktop/Examples/DesktopIntegrationExample.cs Update message handling to work with object-based events Add type checking for DaqifiOutMessage vs string messages Modify event handlers to handle both protobuf and text responses +18/-11
Tests	CoreDeviceAdapterTests.cs Update tests for object-based message events                          src/Daqifi.Core.Tests/Integration/Desktop/CoreDeviceAdapterTests.cs Update event handler signature from string to object type Maintain test compatibility with new message event structure +1/-1

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[qodo-merge-pro]

PR Reviewer Guide 🔍

Here are some key observations to aid the review process:

🎫 Ticket compliance analysis ✅ 35 - PR Code Verified Compliant requirements: • Fix LineBasedMessageParser incompatibility with binary protobuf messages • Support both text-based SCPI command responses and binary protobuf message parsing • Enable MessageReceived events to fire for protobuf responses • Maintain backward compatibility with existing SCPI text-based communication • Provide configurable message parser options in CoreDeviceAdapter Requires further human verification: • Allow Phase 2 integration of CoreDeviceAdapter in daqifi-desktop application • Handle device status responses and data streaming in binary protobuf format

⏱️ Estimated effort to review: 4 🔵🔵🔵🔵⚪

🧪 No relevant tests

🔒 No security concerns identified

⚡ Recommended focus areas for review Logic Issue The null byte detection logic may incorrectly classify legitimate text messages containing null bytes as protobuf. The fallback mechanism tries protobuf parsing even when text parsing succeeds, which could cause performance issues and incorrect message classification. // First, try to detect if this looks like protobuf data (contains null bytes) bool likelyProtobuf = ContainsNullBytes(data); if (likelyProtobuf) { // Try protobuf parser first var protobufMessages = _protobufParser.ParseMessages(data, out int protobufConsumed); if (protobufMessages.Any()) { foreach (var msg in protobufMessages) { messages.Add(new ObjectInboundMessage(msg.Data)); } consumedBytes = protobufConsumed; return messages; } } // Try text parser var textMessages = _textParser.ParseMessages(data, out int textConsumed); if (textMessages.Any()) { foreach (var msg in textMessages) { messages.Add(new ObjectInboundMessage(msg.Data)); } consumedBytes = textConsumed; return messages; } // If text parser didn't work and we haven't tried protobuf yet, try it if (!likelyProtobuf) { var protobufMessages = _protobufParser.ParseMessages(data, out int protobufConsumed); if (protobufMessages.Any()) { foreach (var msg in protobufMessages) { messages.Add(new ObjectInboundMessage(msg.Data)); } consumedBytes = protobufConsumed; } } Parsing Error The protobuf message size calculation and boundary detection logic appears flawed. Using CalculateSize() on a parsed message doesn't guarantee it matches the actual bytes consumed from the input stream, potentially causing message boundary errors. var message = DaqifiOutMessage.Parser.ParseFrom(remainingData); // Calculate how many bytes were consumed for this message var messageBytes = message.CalculateSize(); currentIndex += messageBytes; consumedBytes = currentIndex; messages.Add(new ProtobufMessage(message)); Breaking Change The event signature change from MessageReceivedEventArgs<string> to MessageReceivedEventArgs<object> is a breaking change that could cause compilation errors in existing desktop applications, despite claims of backward compatibility. public event EventHandler<MessageReceivedEventArgs<object>>? MessageReceived {

[qodo-merge-pro]

PR Code Suggestions ✨

Explore these optional code suggestions:

Category	Suggestion	Impact
Possible issue	✅ Fix protobuf byte consumption calculation Suggestion Impact: The suggestion was implemented with the core fix applied - CodedInputStream is now used to track actual bytes consumed during parsing instead of CalculateSize(). The commit includes additional improvements like retry logic and better error handling beyond the original suggestion. code diff: + // Use CodedInputStream for proper byte tracking + var remainingData = new ReadOnlySpan<byte>(data, currentIndex, data.Length - currentIndex); + var codedInput = new CodedInputStream(remainingData.ToArray()); - // Calculate how many bytes were consumed for this message - var messageBytes = message.CalculateSize(); - currentIndex += messageBytes; - consumedBytes = currentIndex; - - messages.Add(new ProtobufMessage(message)); + // Record the position before parsing + var startPosition = codedInput.Position; + + // Try to parse a protobuf message + var message = DaqifiOutMessage.Parser.ParseFrom(codedInput); + + // Calculate actual bytes consumed by the parser + var bytesConsumed = codedInput.Position - startPosition; The protobuf parser incorrectly calculates consumed bytes using CalculateSize(), which returns the serialized size, not the actual bytes consumed during parsing. This can cause data corruption when multiple messages are in the buffer. src/Daqifi.Core/Communication/Consumers/ProtobufMessageParser.cs [35-39] -var message = DaqifiOutMessage.Parser.ParseFrom(remainingData); +// Use CodedInputStream to properly track consumed bytes +var codedInput = new CodedInputStream(remainingData); +var message = DaqifiOutMessage.Parser.ParseFrom(codedInput); -// Calculate how many bytes were consumed for this message -var messageBytes = message.CalculateSize(); -currentIndex += messageBytes; +var bytesConsumed = (int)(codedInput.Position); +currentIndex += bytesConsumed; [Suggestion processed] Suggestion importance[1-10]: 9 __ Why: The suggestion correctly identifies a critical bug where CalculateSize() is used instead of tracking the actual bytes parsed, which could lead to data corruption or parsing failures in a stream with multiple messages.	High
	Prevent infinite loops with unparseable data The fallback logic doesn't update consumedBytes when no messages are parsed, potentially causing the same data to be reprocessed indefinitely and leading to infinite loops. src/Daqifi.Core/Communication/Consumers/CompositeMessageParser.cs [71-83] // If text parser didn't work and we haven't tried protobuf yet, try it if (!likelyProtobuf) { var protobufMessages = _protobufParser.ParseMessages(data, out int protobufConsumed); if (protobufMessages.Any()) { ... consumedBytes = protobufConsumed; } + else if (protobufConsumed == 0 && textConsumed == 0) + { + // Skip one byte to avoid infinite loop with unparseable data + consumedBytes = 1; + } } [To ensure code accuracy, apply this suggestion manually] Suggestion importance[1-10]: 8 __ Why: This suggestion correctly identifies a serious issue where the parser could enter an infinite loop if it receives unparseable data, and the proposed fix is a valid strategy to ensure the system remains responsive.	Medium
General	✅ Improve protobuf message type detection Suggestion Impact: The suggestion's core idea was implemented but with a different approach. Instead of using CodedInputStream.ReadTag(), the commit implemented multiple heuristics including protobuf field tag pattern detection, null byte ratio analysis, and text command pattern recognition to improve message type detection beyond simple null byte checking. code diff: - // First, try to detect if this looks like protobuf data (contains null bytes) - bool likelyProtobuf = ContainsNullBytes(data); - - if (likelyProtobuf) + // Use improved heuristics to detect message type + var messageTypeHint = DetectMessageType(data); + + if (messageTypeHint == MessageTypeHint.LikelyProtobuf) { // Try protobuf parser first var protobufMessages = _protobufParser.ParseMessages(data, out int protobufConsumed); @@ -56,20 +57,37 @@ } } - // Try text parser - var textMessages = _textParser.ParseMessages(data, out int textConsumed); - if (textMessages.Any()) - { - foreach (var msg in textMessages) - { - messages.Add(new ObjectInboundMessage(msg.Data)); - } - consumedBytes = textConsumed; - return messages; - } - - // If text parser didn't work and we haven't tried protobuf yet, try it - if (!likelyProtobuf) + if (messageTypeHint == MessageTypeHint.LikelyText) + { + // Try text parser first + var textMessages = _textParser.ParseMessages(data, out int textConsumed); + if (textMessages.Any()) + { + foreach (var msg in textMessages) + { + messages.Add(new ObjectInboundMessage(msg.Data)); + } + consumedBytes = textConsumed; + return messages; + } + } + + // If heuristics are uncertain or first attempt failed, try the other parser + if (messageTypeHint != MessageTypeHint.LikelyText) + { + var textMessages = _textParser.ParseMessages(data, out int textConsumed); + if (textMessages.Any()) + { + foreach (var msg in textMessages) + { + messages.Add(new ObjectInboundMessage(msg.Data)); + } + consumedBytes = textConsumed; + return messages; + } + } + + if (messageTypeHint != MessageTypeHint.LikelyProtobuf) { var protobufMessages = _protobufParser.ParseMessages(data, out int protobufConsumed); if (protobufMessages.Any()) @@ -86,13 +104,95 @@ } /// <summary> - /// Checks if the data contains null bytes, which indicates binary protobuf data. + /// Message type hints for improved detection. + /// </summary> + private enum MessageTypeHint + { + Uncertain, + LikelyText, + LikelyProtobuf + } + + /// <summary> + /// Uses multiple heuristics to detect the likely message type. + /// Goes beyond simple null byte detection to avoid false positives. + /// </summary> + /// <param name="data">The data to analyze.</param> + /// <returns>A hint about the likely message type.</returns> + private static MessageTypeHint DetectMessageType(byte[] data) + { + if (data.Length == 0) + return MessageTypeHint.Uncertain; + + // Heuristic 1: Check for common text patterns (SCPI commands) + if (data.Length > 3 && IsLikelyTextCommand(data)) + { + return MessageTypeHint.LikelyText; + } + + // Heuristic 2: Check for protobuf-like patterns + if (IsLikelyProtobufData(data)) + { + return MessageTypeHint.LikelyProtobuf; + } + + // Heuristic 3: High ratio of null bytes suggests binary + var nullByteRatio = data.Count(b => b == 0) / (double)data.Length; + if (nullByteRatio > 0.1) // More than 10% null bytes + { + return MessageTypeHint.LikelyProtobuf; + } + + // Heuristic 4: Check for printable ASCII (common in SCPI) + var printableRatio = data.Count(b => b >= 32 && b <= 126) / (double)data.Length; + if (printableRatio > 0.8) // More than 80% printable ASCII + { + return MessageTypeHint.LikelyText; + } + + return MessageTypeHint.Uncertain; + } + + /// <summary> + /// Checks if the data looks like a text command (SCPI-style). /// </summary> /// <param name="data">The data to check.</param> - /// <returns>True if the data contains null bytes, false otherwise.</returns> - private static bool ContainsNullBytes(byte[] data) - { - return data.Contains((byte)0); + /// <returns>True if it looks like a text command.</returns> + private static bool IsLikelyTextCommand(byte[] data) + { + // Check for common SCPI patterns + var text = System.Text.Encoding.ASCII.GetString(data, 0, Math.Min(data.Length, 10)); + return text.StartsWith("*") || text.StartsWith("SYST") || text.StartsWith("CONF") || + text.StartsWith("READ", StringComparison.OrdinalIgnoreCase) || + text.EndsWith("\r\n") || text.EndsWith("\n"); + } + + /// <summary> + /// Checks if the data has protobuf-like characteristics. + /// </summary> + /// <param name="data">The data to check.</param> + /// <returns>True if it looks like protobuf data.</returns> + private static bool IsLikelyProtobufData(byte[] data) + { + if (data.Length < 2) + return false; + + // Protobuf messages often start with field tags (varint encoded) + // Check for patterns that suggest protobuf field encoding + for (int i = 0; i < Math.Min(data.Length - 1, 5); i++) + { + var byte1 = data[i]; + var byte2 = data[i + 1]; + + // Look for varint patterns (field number + wire type) + if ((byte1 & 0x07) <= 5 && // Valid wire type (0-5) + (byte1 >> 3) > 0) // Non-zero field number + { + return true; + } + } + + return false; } Using null byte detection alone is unreliable for distinguishing protobuf from text data, as text messages could contain null bytes or protobuf messages might not have them in the first few bytes. src/Daqifi.Core/Communication/Consumers/CompositeMessageParser.cs [41-42] -// First, try to detect if this looks like protobuf data (contains null bytes) -bool likelyProtobuf = ContainsNullBytes(data); +// Try to detect protobuf by attempting to parse the first few bytes as a varint +bool likelyProtobuf = IsLikelyProtobuf(data); +private static bool IsLikelyProtobuf(byte[] data) +{ + if (data.Length < 2) return false; + + try + { + var codedInput = new CodedInputStream(data); + // Try to read a varint (protobuf messages start with field tags) + codedInput.ReadTag(); + return true; + } + catch + { + return false; + } +} + [Suggestion processed] Suggestion importance[1-10]: 6 __ Why: The suggestion correctly points out that detecting protobuf based on null bytes is unreliable and proposes a much more robust method, which improves the parser's reliability and performance.	Low
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