Added check for invalid json in JsonSocketMessageHandler and virtual GetTypeIdentifierNonJson for handling non-json messages

Added parsing of REST response data up to 128 characters for error responses
2026-04-12 16:13:12 +00:00 · 2026-02-22 16:29:05 +01:00 · 2026-02-22 16:05:49 +01:00
6 changed files with 84 additions and 22 deletions
--- a/CryptoExchange.Net.UnitTests/RestClientTests.cs
+++ b/CryptoExchange.Net.UnitTests/RestClientTests.cs
@ -81,6 +81,25 @@ namespace CryptoExchange.Net.UnitTests
            Assert.That(result.Error is ServerError);
        }

+
+        [TestCase]
+        public async Task ReceivingErrorAndNotParsingErrorAndInvalidJson_Should_ContainData()
+        {
+            // arrange
+            var client = new TestRestClient();
+            var response = "<html>...</html>";
+            client.SetErrorWithResponse(response, System.Net.HttpStatusCode.BadRequest);
+
+            // act
+            var result = await client.Api1.Request<TestObject>();
+
+            // assert
+            ClassicAssert.IsFalse(result.Success);
+            Assert.That(result.Error != null);
+            Assert.That(result.Error is ServerError);
+            Assert.That(result.Error.Message.Contains(response));
+        }
+
        [TestCase]
        public async Task ReceivingErrorAndParsingError_Should_ResultInParsedError()
        {
--- a/CryptoExchange.Net.UnitTests/TestImplementations/TestRestMessageHandler.cs
+++ b/CryptoExchange.Net.UnitTests/TestImplementations/TestRestMessageHandler.cs
@ -19,11 +19,14 @@ namespace CryptoExchange.Net.UnitTests.TestImplementations
        private ErrorMapping _errorMapping = new ErrorMapping([]);
        public override JsonSerializerOptions Options => new JsonSerializerOptions();

-        public override ValueTask<Error> ParseErrorResponse(int httpStatusCode, HttpResponseHeaders responseHeaders, Stream responseStream)
+        public override async ValueTask<Error> ParseErrorResponse(int httpStatusCode, HttpResponseHeaders responseHeaders, Stream responseStream)
        {
-            var errorData = JsonSerializer.Deserialize<TestError>(responseStream);
+            var result = await GetJsonDocument(responseStream).ConfigureAwait(false);
+            if (result.Item1 != null)
+                return result.Item1;

-            return new ValueTask<Error>(new ServerError(errorData.ErrorCode, _errorMapping.GetErrorInfo(errorData.ErrorCode.ToString(), errorData.ErrorMessage)));
+            var errorData = result.Item2.Deserialize<TestError>();
+            return new ServerError(errorData.ErrorCode, _errorMapping.GetErrorInfo(errorData.ErrorCode.ToString(), errorData.ErrorMessage));
        }
    }
 }
--- a/CryptoExchange.Net/Clients/RestApiClient.cs
+++ b/CryptoExchange.Net/Clients/RestApiClient.cs
@ -437,23 +437,19 @@ namespace CryptoExchange.Net.Clients
                responseStream = await response.GetResponseStreamAsync(cancellationToken).ConfigureAwait(false);
                string? originalData = null;
                var outputOriginalData = ApiOptions.OutputOriginalData ?? ClientOptions.OutputOriginalData;
-                if (outputOriginalData || MessageHandler.RequiresSeekableStream)
+                if (outputOriginalData || MessageHandler.RequiresSeekableStream || !response.IsSuccessStatusCode)
                {
-                    // If we want to return the original string data from the stream, but still want to process it
-                    // we'll need to copy it as the stream isn't seekable, and thus we can only read it once
-                    var memoryStream = new MemoryStream();
-                    await responseStream.CopyToAsync(memoryStream).ConfigureAwait(false);
-                    using var reader = new StreamReader(memoryStream, Encoding.UTF8, false, 4096, true);
-                    if (outputOriginalData) 
+                    // Create a seekable stream from the response stream if:
+                    // 1. We need to output the original data
+                    // 2. The message handler requires a seekable stream
+                    // 3. The response indicates error and we want to output (part of) the returned data
+                    responseStream = await CopyStreamAsync(responseStream).ConfigureAwait(false);
+                    using var reader = new StreamReader(responseStream, Encoding.UTF8, false, 4096, true);
+                    if (outputOriginalData)
                    {
-                        memoryStream.Position = 0;
                        originalData = await reader.ReadToEndAsync().ConfigureAwait(false);
+                        responseStream.Position = 0;
                    }
-
-                    // Continue processing from the memory stream since the response stream is already read and we can't seek it
-                    responseStream.Close();
-                    memoryStream.Position = 0;
-                    responseStream = memoryStream;
                }

                if (!response.IsSuccessStatusCode && !requestDefinition.TryParseOnNonSuccess)
@ -479,13 +475,12 @@ namespace CryptoExchange.Net.Clients
                    else
                    {
                        // Handle a 'normal' error response. Can still be either a json error message or some random HTML or other string
-
                        try
                        {
                            error = await MessageHandler.ParseErrorResponse(
-                            (int)response.StatusCode,
-                            response.ResponseHeaders,
-                            responseStream).ConfigureAwait(false);
+                                (int)response.StatusCode,
+                                response.ResponseHeaders,
+                                responseStream).ConfigureAwait(false);
                        }
                        catch (Exception ex)
                        {
@ -769,6 +764,15 @@ namespace CryptoExchange.Net.Clients
            }
        }

+        private async Task<Stream> CopyStreamAsync(Stream responseStream)
+        {
+            var memoryStream = new MemoryStream();
+            await responseStream.CopyToAsync(memoryStream).ConfigureAwait(false);
+            responseStream.Close();
+            memoryStream.Position = 0;
+            return memoryStream;
+        }
+
        private bool ShouldCache(RequestDefinition definition)
            => ClientOptions.CachingEnabled
            && definition.Method == HttpMethod.Get
--- a/CryptoExchange.Net/Converters/SystemTextJson/MessageHandlers/JsonRestMessageHandler.cs
+++ b/CryptoExchange.Net/Converters/SystemTextJson/MessageHandlers/JsonRestMessageHandler.cs
@ -18,6 +18,7 @@ namespace CryptoExchange.Net.Converters.SystemTextJson.MessageHandlers
    public abstract class JsonRestMessageHandler : IRestMessageHandler
    {
        private static MediaTypeWithQualityHeaderValue _acceptJsonContent = new MediaTypeWithQualityHeaderValue(Constants.JsonContentHeader);
+        private const int _errorResponseSnippetLimit = 128;

        /// <summary>
        /// Empty rate limit error
@ -80,7 +81,20 @@ namespace CryptoExchange.Net.Converters.SystemTextJson.MessageHandlers
            }
            catch (Exception ex)
            {
-                return (new ServerError(new ErrorInfo(ErrorType.DeserializationFailed, false, "Deserialization failed, invalid JSON"), ex), null);
+                var errorMsg = "Deserialization failed, invalid JSON";
+                if (stream.CanSeek)
+                {
+                    var dataSnippet = new char[_errorResponseSnippetLimit];
+                    stream.Seek(0, SeekOrigin.Begin);
+                    var written = new StreamReader(stream).ReadBlock(dataSnippet, 0, _errorResponseSnippetLimit);
+                    var data = new string(dataSnippet, 0, written);
+                    errorMsg += $": {data}";
+                    if (data.Length == _errorResponseSnippetLimit)
+                        errorMsg += " (truncated)";
+                }
+
+                var error = new DeserializeError(errorMsg, ex);
+                return (error, null);
            }
        }

--- a/CryptoExchange.Net/Converters/SystemTextJson/MessageHandlers/JsonSocketMessageHandler.cs
+++ b/CryptoExchange.Net/Converters/SystemTextJson/MessageHandlers/JsonSocketMessageHandler.cs
@ -165,6 +165,14 @@ namespace CryptoExchange.Net.Converters.SystemTextJson.MessageHandlers
            return null;
        }

+        /// <summary>
+        /// Return type identifier for non-json messages
+        /// </summary>
+        protected virtual string? GetTypeIdentifierNonJson(ReadOnlySpan<byte> data, WebSocketMessageType? webSocketMessageType)
+        {
+            return null;
+        }
+
        /// <inheritdoc />
        public virtual string? GetTypeIdentifier(ReadOnlySpan<byte> data, WebSocketMessageType? webSocketMessageType)
        {
@ -173,6 +181,12 @@ namespace CryptoExchange.Net.Converters.SystemTextJson.MessageHandlers
            int? arrayIndex = null;

            _searchResult.Clear();
+            if (data[0] != 0x5B && data[0] != 0x7B)
+            {
+                // Message doesn't start with `{` or `[`, not valid for processing as json
+                return GetTypeIdentifierNonJson(data, webSocketMessageType);
+            }
+
            var reader = new Utf8JsonReader(data);
            while (reader.Read())
            {
--- a/CryptoExchange.Net/Objects/Error.cs
+++ b/CryptoExchange.Net/Objects/Error.cs
@ -211,7 +211,15 @@ namespace CryptoExchange.Net.Objects
        /// <summary>
        /// ctor
        /// </summary>
-        public DeserializeError(string? message = null, Exception? exception = null) : base(null, _errorInfo with { Message = (message?.Length > 0 ? _errorInfo.Message + ": " + message : _errorInfo.Message) }, exception) { }
+        public DeserializeError(string? message = null, Exception? exception = null) 
+            : base(null, 
+                  _errorInfo with 
+                  {
+                      Message = message?.Length > 0 
+                        ? message
+                        : _errorInfo.Message
+                  },
+                  exception) { }
    }

    /// <summary>
Author	SHA1	Message	Date
JKorf	0ce2e778f4	Added check for invalid json in JsonSocketMessageHandler and virtual GetTypeIdentifierNonJson for handling non-json messages	2026-02-22 16:29:05 +01:00
JKorf	36c2411d46	Added parsing of REST response data up to 128 characters for error responses	2026-02-22 16:05:49 +01:00