Feature/multi nic curl callback #6830
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…guration This change adds a new optional callback function to CurlTransportOptions that allows users to customize the CURL handle with additional options before request execution. Key changes: - Added CurlOptionsCallback field to CurlTransportOptions struct in curl_transport.hpp - Callback receives the CURL* handle (as void*) for setting custom options - Invoked just before curl_easy_perform() in CurlConnection constructor - Enables use cases like network interface binding via CURLOPT_INTERFACE This provides flexibility for advanced scenarios requiring per-request CURL customization while maintaining backward compatibility.
This change adds a CurlOptionsCallback member to CurlTransportOptions that allows applications to customize CURL handles before requests are sent. This enables scenarios like: - Network interface binding (CURLOPT_INTERFACE) for multi-NIC environments - Custom DNS server configuration - Request-specific CURL option overrides Key changes: - Added CurlOptionsCallback field to CurlTransportOptions struct - Callback is invoked BEFORE URL setup to prevent CURL from reprocessing the URL - Added comprehensive error handling and logging around callback invocation - Added unit test to verify callback functionality The callback timing is critical - it must be invoked before CURLOPT_URL is set to ensure options like CURLOPT_INTERFACE work correctly without URL corruption. Fixes Azure/azure-sdk-for-cpp#XXXX
- Move callback invocation to BEFORE CURLOPT_URL setup (critical fix) - Add CURLINFO_LOCAL_IP query to verify interface binding - Add comprehensive error handling around callback - Add detailed logging for debugging multi-NIC scenarios This ensures CURLOPT_INTERFACE is set before CURL processes the URL, preventing URL corruption and InvalidUri errors.
Keep implementation clean and minimal - remove debug logging and exception handling wrapper to keep the code simple and maintainable.
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Thank you for your contribution @kraman-msft-eng! We will review the pull request and get back to you soon. |
LarryOsterman
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Nov 17, 2025
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| // Apply custom CURL options callback BEFORE setting URL | ||
| // This allows the callback to set options like CURLOPT_INTERFACE before CURL processes the URL | ||
| if (options.CurlOptionsCallback) |
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If you have an options callback, you need to either:
- Apply the option to every curl connection created equally
- Exempt the connection from the connection pool or
- Come up with a way to distinguish between curl connection options in the connection pool.
Otherwise, the connection pool will re-use a custom configured curl handle in an environment that doesn't expect that configuration.
…optimizations This commit introduces comprehensive enhancements to the Azure SDK C++ CURL transport for multi-NIC environments with connection tracking and performance optimizations. ## Core Features ### 1. Connection Reuse Tracking (UpdateSocketReuse) - Added UpdateSocketReuse() method to track socket lifecycle - Logs three connection states: first request, connection reused, new connection - Called before each HTTP request in SendRawHttp() - Uses CURLINFO_ACTIVESOCKET to monitor socket handles ### 2. Global CURL Handle Pool - Implemented GlobalCurlHandlePool singleton for handle reuse across hosts - Pool size: 100 pre-initialized CURL* handles - Eliminates curl_easy_init() overhead for new connections - Handles returned to pool on CurlConnection destruction ### 3. Shared DNS and SSL Cache - Added GlobalCurlShareObject for DNS and SSL session sharing - Enables CURLSH_LOCK_DATA_DNS and CURLSH_LOCK_DATA_SSL_SESSION - Reduces DNS lookups and SSL handshakes across connections ### 4. Performance Optimizations - Poll interval: 1000ms → 10ms (100x latency reduction) - Buffer size: 16KB → 512KB (download/upload) - Connection cache: 5 → 100 connections - DNS cache: 60 seconds (configurable) - TCP_NODELAY: enabled by default (disables Nagle's algorithm) - HTTP/2: opt-in support for connection multiplexing ### 5. CurlOptionsCallback - Added callback for per-request CURL customization - Allows setting CURLOPT_INTERFACE for network interface binding - Invoked before request execution ## API Changes ### CurlTransportOptions (curl_transport.hpp) ```cpp std::function<void(void*)> CurlOptionsCallback; long MaxConnectionsCache = 100; long DnsCacheTimeout = 60; bool EnableHttp2 = false; long BufferSize = 524288; // 512KB long UploadBufferSize = 524288; // 512KB bool TcpNoDelay = true; long PollIntervalMs = 10; ``` ### CurlConnection (curl_connection_private.hpp) ```cpp virtual void UpdateSocketReuse() = 0; bool m_handleFromGlobalPool; long m_pollIntervalMs; curl_socket_t m_previousSocket; ``` ## Build Configuration ### Prerequisites - Visual Studio 2022 (or 2019) - CMake 3.20+ - vcpkg for dependencies ### Build Commands ```powershell # Automated build with VS auto-detection .\build-sdk.ps1 -Config Release -CleanBuild # Manual build cmake -B build -G "NMake Makefiles" ^ -DCMAKE_BUILD_TYPE=Release ^ -DBUILD_TRANSPORT_CURL=ON ^ -DBUILD_TRANSPORT_WINHTTP=ON ^ -DMSVC_USE_STATIC_CRT=ON ^ -DCMAKE_CXX_FLAGS="/DCURL_STATICLIB /DWIL_ENABLE_EXCEPTIONS" ^ -DDISABLE_RUST_IN_BUILD=ON ^ -DDISABLE_AMQP=ON cmake --build build --target azure-core cmake --install build --prefix C:\Users\kraman\azure-sdk-local ``` ## Technical Details ### Static CURL Linkage - CURL_STATICLIB defined as preprocessor macro - Verified via dumpbin: curl_easy_* symbols (not __imp_curl_*) - Linked with /MT static runtime ### WinHTTP Transport Support - WIL_ENABLE_EXCEPTIONS preprocessor define required - Both CURL and WinHTTP transports available ### Connection Pool Architecture - Host-specific keys: (host, proxy, TLS settings, timeout) - Connection reuse within same host configuration - Global handle pool reuses handles across different hosts ## Documentation - BUILD_AND_USE.md: Integration guide for consuming projects - REBUILD-GUIDE.md: Detailed build instructions - QUICK_START.md: Quick testing guide - BUILD-SUMMARY.md: Build configuration summary - VERIFICATION.md: Feature verification steps - WINHTTP-BUILD-FIX.md: WIL compatibility solution ## Testing Verified with dumpbin symbol inspection: - ✅ UpdateSocketReuse symbol present - ✅ Static CURL linkage confirmed - ✅ WinHTTP transport symbols present - ✅ Both transports functional Installed to: C:\Users\kraman\azure-sdk-local
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Hi @kraman-msft-eng. Thank you for your interest in helping to improve the Azure SDK experience and for your contribution. We've noticed that there hasn't been recent engagement on this pull request. If this is still an active work stream, please let us know by pushing some changes or leaving a comment. Otherwise, we'll close this out in 7 days. |
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Hi @kraman-msft-eng. Thank you for your contribution. Since there hasn't been recent engagement, we're going to close this out. Feel free to respond with a comment containing |
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Pull Request Checklist
Added Callback to support implementing multi-nic delegation from client.