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Stop logging stdio transport environment variables #1538

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Copilot Apr 29, 2026
c1e6dc8
Stop logging stdio environment variables
Copilot Apr 29, 2026
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7 changes: 3 additions & 4 deletions src/ModelContextProtocol.Core/Client/StdioClientTransport.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -121,9 +121,8 @@ public async Task<ITransport> ConnectAsync(CancellationToken cancellationToken =

if (logger.IsEnabled(LogLevel.Trace))
{
LogCreateProcessForTransportSensitive(logger, endpointName, _options.Command,
LogCreateProcessForTransportDetailed(logger, endpointName, _options.Command,
startInfo.Arguments,
string.Join(", ", startInfo.Environment.Select(kvp => $"{kvp.Key}={kvp.Value}")),
startInfo.WorkingDirectory);
}
else
Expand Down Expand Up @@ -295,8 +294,8 @@ private static string EscapeArgumentString(string argument) =>
[LoggerMessage(Level = LogLevel.Information, Message = "{EndpointName} starting server process. Command: '{Command}'.")]
private static partial void LogCreateProcessForTransport(ILogger logger, string endpointName, string command);

[LoggerMessage(Level = LogLevel.Trace, Message = "{EndpointName} starting server process. Command: '{Command}', Arguments: {Arguments}, Environment: {Environment}, Working directory: {WorkingDirectory}.")]
private static partial void LogCreateProcessForTransportSensitive(ILogger logger, string endpointName, string command, string? arguments, string environment, string workingDirectory);
[LoggerMessage(Level = LogLevel.Trace, Message = "{EndpointName} starting server process. Command: '{Command}', Arguments: {Arguments}, Working directory: {WorkingDirectory}.")]
private static partial void LogCreateProcessForTransportDetailed(ILogger logger, string endpointName, string command, string? arguments, string workingDirectory);

[LoggerMessage(Level = LogLevel.Warning, Message = "{EndpointName} failed to start server process.")]
private static partial void LogTransportProcessStartFailed(ILogger logger, string endpointName);
Expand Down
39 changes: 38 additions & 1 deletion tests/ModelContextProtocol.Tests/Transport/StdioClientTransportTests.cs
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Original file line number Diff line number Diff line change
@@ -1,4 +1,5 @@
using ModelContextProtocol.Client;
using Microsoft.Extensions.Logging;
using ModelContextProtocol.Client;
using ModelContextProtocol.Protocol;
using ModelContextProtocol.Tests.Utils;
using System.IO.Pipelines;
Expand All @@ -12,6 +13,42 @@ public class StdioClientTransportTests(ITestOutputHelper testOutputHelper) : Log
{
public static bool IsStdErrCallbackSupported => !PlatformDetection.IsMonoRuntime;

[Fact]
public async Task ConnectAsync_DoesNotLogEnvironmentVariablesAtTrace()
{
string secretName = $"MCP_TEST_SECRET_{Guid.NewGuid():N}";
string secretValue = $"secret-{Guid.NewGuid():N}";

using var loggerFactory = Microsoft.Extensions.Logging.LoggerFactory.Create(builder =>
{
builder.AddProvider(MockLoggerProvider);
builder.SetMinimumLevel(LogLevel.Trace);
});

StdioClientTransport transport = RuntimeInformation.IsOSPlatform(OSPlatform.Windows) ?
new(new()
{
Command = "cmd.exe",
Arguments = ["/c", "exit /b 0"],
EnvironmentVariables = new Dictionary<string, string?> { [secretName] = secretValue },
}, loggerFactory) :
new(new()
{
Command = "sh",
Arguments = ["-c", "exit 0"],
EnvironmentVariables = new Dictionary<string, string?> { [secretName] = secretValue },
}, loggerFactory);

await using var _ = await transport.ConnectAsync(TestContext.Current.CancellationToken);

Assert.Contains(MockLoggerProvider.LogMessages, log =>
log.LogLevel == LogLevel.Trace &&
log.Message.Contains("starting server process", StringComparison.Ordinal));
Assert.DoesNotContain(MockLoggerProvider.LogMessages, log =>
log.Message.Contains(secretName, StringComparison.Ordinal) ||
log.Message.Contains(secretValue, StringComparison.Ordinal));
}

[Fact]
public async Task CreateAsync_ValidProcessInvalidServer_Throws()
{
Expand Down