Code review: Fix input validation, resource leaks, and error handling in samples

[Copilot]

Comprehensive code review identified critical issues in samples across .NET, Java, and Node.js: missing input validation, resource leaks, and silent error handling.

Changes

Input Validation (8 files)

• Validate command-line arguments for null/empty strings before use
• Exit early with clear error messages

// Before: crashes on empty strings
var ns = args[0];

// After: validates and fails fast
if (string.IsNullOrWhiteSpace(ns)) {
    Console.WriteLine("Error: All arguments must be non-empty");
    return;
}

Resource Management (6 files)

• Wrap HttpClient in using statements (.NET)
• Convert Scanner to try-with-resources (Java)
• Move resource cleanup outside try blocks where appropriate

Error Handling (5 files)

• Log errors to stderr instead of stdout
• Add connection failure handlers for WebSocket clients
• Replace empty catch blocks with descriptive error messages

Repository Maintenance

• Remove accidentally committed binary (.nuget/nuget.exe)
• Update .gitignore to exclude .nuget/

Files Modified

• 5 .NET samples (simple-http, simple-websocket, rolebasedaccesscontrol)
• 5 Java samples (HttpListener, HttpSender, WebsocketListener, WebsocketSender)
• 3 Node.js samples (hyco-websocket-simple, hyco-https-simple)

All changes are backward compatible. See CODE_REVIEW_SUMMARY.md for detailed findings and additional recommendations.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• dotnet.myget.org
  • Triggering command: /usr/bin/dotnet dotnet restore --no-dependencies /home/REDACTED/work/azure-relay/azure-relay/samples/hybrid-connections/dotnet/aspnet/samples/SelfHostServer/SelfHostServer.csproj --packages /home/REDACTED/work/azure-relay/.codeql-scratch/dbs/csharp/working/packages /p:DisableImplicitNuGetFallbackFolder=true --verbosity normal /p:TargetFrameworkRootPath=/home/REDACTED/work/azure-relay/.codeql-scratch/dbs/csharp/working/emptyFakeDotnetRoot /p:NetCoreTargetingPackRoot=/home/REDACTED/work/azure-relay/.codeql-scratch/dbs/csharp/working/emptyFakeDotnetRoot (dns block)
  • Triggering command: /usr/bin/dotnet dotnet restore --no-dependencies /home/REDACTED/work/azure-relay/azure-relay/samples/hybrid-connections/dotnet/aspnet/samples/MVCServerApp/MVCServerApp.csproj --packages /home/REDACTED/work/azure-relay/.codeql-scratch/dbs/csharp/working/packages /p:DisableImplicitNuGetFallbackFolder=true --verbosity normal /p:TargetFrameworkRootPath=/home/REDACTED/work/azure-relay/.codeql-scratch/dbs/csharp/working/emptyFakeDotnetRoot /p:NetCoreTargetingPackRoot=/home/REDACTED/work/azure-relay/.codeql-scratch/dbs/csharp/working/emptyFakeDotnetRoot (dns block)
  • Triggering command: /usr/bin/dotnet dotnet restore --no-dependencies /home/REDACTED/work/azure-relay/azure-relay/samples/hybrid-connections/dotnet/aspnet/src/Microsoft.AspNetCore.Server.AzureRelay/Microsoft.Azure.Relay.AspNetCore.csproj --packages /home/REDACTED/work/azure-relay/.codeql-scratch/dbs/csharp/working/packages /p:DisableImplicitNuGetFallbackFolder=true --verbosity normal /p:TargetFrameworkRootPath=/home/REDACTED/work/azure-relay/.codeql-scratch/dbs/csharp/working/emptyFakeDotnetRoot /p:NetCoreTargetingPackRoot=/home/REDACTED/work/azure-relay/.codeql-scratch/dbs/csharp/working/emptyFakeDotnetRoot (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

---

✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.