Fixes and improvements in native socket

[josesimoes]

Description

• Fix mapping SOCK_ENOTCONN error.
• Add wait events call on send/receive error to prevent race with lwIP stack.
• Adjust TCP_SYNMAXRTX lwIP config to get ~30seconds timeout on connect.
• Update declaration of Sys.Net assembly.

Motivation and Context

• Addresses Bug when reconnecting to MQTT Home#1692
• Following Remove unused code in Socket System.Net#373 and - Following Add Connect to Socket System.Net#374

How Has This Been Tested?

• Running MQTT test broker provided in the issue.

Screenshots

Types of changes

• Improvement (non-breaking change that improves a feature, code or algorithm)
• Bug fix (non-breaking change which fixes an issue with code or algorithm)
• New feature (non-breaking change which adds functionality to code)
• Breaking change (fix or feature that would cause existing functionality to change)
• Config and build (change in the configuration and build system, has no impact on code or features)
• Dev Containers (changes related with Dev Containers, has no impact on code or features)
• Dependencies/declarations (update dependencies or assembly declarations and changes associated, has no impact on code or features)
• Documentation (changes or updates in the documentation, has no impact on code or features)

Checklist

• My code follows the code style of this project (only if there are changes in source code).
• My changes require an update to the documentation (there are changes that require the docs website to be updated).
• I have updated the documentation accordingly (the changes require an update on the docs in this repo).
• I have read the CONTRIBUTING document.
• I have tested everything locally and all new and existing tests passed (only if there are changes in source code).

Summary by CodeRabbit

Release Notes

• Bug Fixes

  • Improved socket operation responsiveness by preventing tight retry loops during non-blocking operations
  • Fixed socket error code mapping for non-connected state scenarios

• Configuration

  • Standardized TCP SYN retransmission retry limits across all supported platforms (ESP32 variants, ChibiOS, FreeRTOS) for more consistent connection behavior

[coderabbitai]

Walkthrough

This PR updates the System.Net native interface by adjusting method lookup table indexing and field constants, adds scheduler-aware error handling for non-blocking socket operations, corrects an error code mapping, and standardizes TCP SYN retransmission configuration across multiple platform targets by introducing the TCP_SYNMAXRTX parameter.

Changes

Cohort / File(s)	Summary
System.Net Native Interface src/DeviceInterfaces/System.Net/sys_net_native.cpp, src/DeviceInterfaces/System.Net/sys_net_native.h	Updated method lookup table with additional NULL entry, adjusted assembly hash, incremented method metadata tuple, and reassigned Socket field index constants (removed FIELD___nonBlockingConnectInProgress and FIELD___nonBlockingConnectRightEndPoint; shifted FIELD___rightEndPoint from 9 to 7).
Socket Error Handling src/DeviceInterfaces/System.Net/sys_net_native_System_Net_Sockets_NativeSocket.cpp, src/PAL/Lwip/lwIP_Sockets.cpp	Added WaitEvents scheduler yield in SendRecvHelper on EWOULDBLOCK error to prevent tight retry loops; corrected ENOTCONN error mapping from SOCK_EISCONN to SOCK_ENOTCONN.
LwIP TCP Retransmission Configuration targets/ChibiOS/_include/lwipopts.h, targets/FreeRTOS/_common/include/lwipopts.h	Added TCP_SYNMAXRTX macro definition (defaults to 4) for compile-time TCP SYN retransmission limit control.
ESP32 Platform Configurations targets/ESP32/_IDF/sdkconfig.default*	Added CONFIG_LWIP_TCP_SYNMAXRTX=4 setting to 18 ESP32 variant sdkconfig files, standardizing TCP SYN retransmission behavior across all ESP32 targets.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~22 minutes

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'Fixes and improvements in native socket' accurately summarizes the main change: addressing socket-related fixes and improvements across the native socket layer and configuration.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Inline comments:
In `@targets/ESP32/_IDF/sdkconfig.default`:
- Line 58: The TCP SYN retransmission count CONFIG_LWIP_TCP_SYNMAXRTX is set to
4 but does not reach the intended ~30s connect timeout; update
CONFIG_LWIP_TCP_SYNMAXRTX from 4 to 5 so that, given
CONFIG_LWIP_TCP_RTO_TIME=1500 ms, the SYN retransmission schedule yields ~31.5s
total timeout and meets the target.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Pro

Run ID: b3e21377-abbb-4c63-b457-15673a0046c2

📥 Commits

Reviewing files that changed from the base of the PR and between be1bb6f and 1825493.

📒 Files selected for processing (25)

• src/DeviceInterfaces/System.Net/sys_net_native.cpp
• src/DeviceInterfaces/System.Net/sys_net_native.h
• src/DeviceInterfaces/System.Net/sys_net_native_System_Net_Sockets_NativeSocket.cpp
• src/PAL/Lwip/lwIP_Sockets.cpp
• targets/ChibiOS/_include/lwipopts.h
• targets/ESP32/_IDF/sdkconfig.default
• targets/ESP32/_IDF/sdkconfig.default.esp32c3
• targets/ESP32/_IDF/sdkconfig.default.esp32c5
• targets/ESP32/_IDF/sdkconfig.default.esp32c6
• targets/ESP32/_IDF/sdkconfig.default.esp32h2
• targets/ESP32/_IDF/sdkconfig.default.esp32p4
• targets/ESP32/_IDF/sdkconfig.default.esp32s2
• targets/ESP32/_IDF/sdkconfig.default.esp32s3
• targets/ESP32/_IDF/sdkconfig.default_ble.esp32s3
• targets/ESP32/_IDF/sdkconfig.default_ble_rev3.esp32
• targets/ESP32/_IDF/sdkconfig.default_nopsram.esp32
• targets/ESP32/_IDF/sdkconfig.default_nopsram_ble.esp32
• targets/ESP32/_IDF/sdkconfig.default_nopsram_rev3.esp32
• targets/ESP32/_IDF/sdkconfig.default_octal_ble.esp32s3
• targets/ESP32/_IDF/sdkconfig.default_pico
• targets/ESP32/_IDF/sdkconfig.default_rev3.esp32
• targets/ESP32/_IDF/sdkconfig.default_rev3.esp32c3
• targets/ESP32/_IDF/sdkconfig.default_rev3_ipv6.esp32
• targets/ESP32/_IDF/sdkconfig.default_rev3_noconsole.esp32c3
• targets/FreeRTOS/_common/include/lwipopts.h