Robust TCP/IP Hardening

[jorgesg82]

Robust TCP/IP Hardening

Summary

This PR hardens the ST-LIB TCP/UDP communication layer on top of lwIP, based on issues reproduced on real hardware under load, fragmentation, and reconnect scenarios.

• Fixes TCP stream handling so small/fragmented segments are not silently dropped.
• Improves send-path behavior under backpressure to reduce intermittent delivery failures.
• Makes ServerSocket lifecycle handling safer across disconnects, close/reopen sequences, and PCB reuse.
• Hardens DatagramSocket and pbuf processing to avoid unstable UDP parsing paths.
• Aligns lwIP/ICMP checksum behavior with hardware checksum offload, improving ping behavior.

Impact

These changes reduce silent packet corruption, improve connection stability during stress/soak testing, and make the socket layer more reliable for production boards that depend on strict TCP session behavior.

Validation

It has been validated on a Nucleo Development Board with repeated stress, reconnect, burst, UDP round-trip, and long-duration soak tests. Those test scripts will be uploaded to the template-project

Notes

Even though it has been hardly tested on a Nucleo, this PR will remain as a draft until I validate it on a real board, because this is a critical change, and will affect Levión testing

[Copilot]

Pull request overview

This PR hardens the TCP/UDP communication layer built on top of lwIP for STM32-based embedded systems. It addresses real bugs reproduced on hardware including fragmented TCP stream handling, silent packet drops, and unsafe socket lifecycle management. The changes eliminate several crash-prone and UB-inducing patterns (e.g., calling destructor directly, using nullptr PCBs without guards, direct type-punned pointer dereferences for unaligned data), and replace them with robust patterns using move semantics, null guards, stream-based reassembly, and proper resource management.

Changes:

• Server, ServerSocket, and Socket are hardened with null guards, corrected move semantics, proper PCB lifecycle management, and stream-based TCP reassembly to handle fragmentation
• DatagramSocket fixes the move constructor self-reference bug (remote_port(remote_port) → remote_port(other.remote_port)), adds null guards, and uses pbuf copy for safe packet parsing
• PacketValue.hpp replaces direct pointer dereferences with memcpy to avoid undefined behavior from type-punned and potentially unaligned reads; lwipopts.h disables ICMP software checksumming to align with hardware offload

Reviewed changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
Src/ST-LIB_LOW/Communication/Server/Server.cpp	Server lifecycle hardening: null guards, capacity enforcement, compaction loop replacing FAULT status transitions
Src/HALAL/Services/Communication/Ethernet/LWIP/UDP/DatagramSocket.cpp	Fixes move constructor bug, adds null guards, proper close/reconnect, pbuf-safe receive callback
Src/HALAL/Services/Communication/Ethernet/LWIP/TCP/Socket.cpp	Full TCP socket hardening: move semantics, stream-based reassembly, corrected callbacks, ERR_ABRT handling
Src/HALAL/Services/Communication/Ethernet/LWIP/TCP/ServerSocket.cpp	Server socket hardening: stream reassembly, correct accept_callback with arg fallback, idempotent close
LWIP/Target/lwipopts.h	Disables ICMP software checksum gen/check for hardware offload alignment
Inc/ST-LIB_LOW/Communication/Server/Server.hpp	Changes broadcast_order from void to bool
Inc/HALAL/Services/Communication/Ethernet/LWIP/UDP/DatagramSocket.hpp	In-class nullptr init for udp_control_block
Inc/HALAL/Services/Communication/Ethernet/LWIP/TCP/Socket.hpp	Adds rx_stream_buffer, clear_packet_queues, connect_poll_ticks, MAX_TX_QUEUE_DEPTH; tightens send_order
Inc/HALAL/Services/Communication/Ethernet/LWIP/TCP/ServerSocket.hpp	Adds rx_stream_buffer, clear_packet_queues, is_listening(); raises MAX_TX_QUEUE_DEPTH to 64; tightens send_order
Inc/HALAL/Models/Packets/PacketValue.hpp	Replaces type-punned pointer dereferences with memcpy for unaligned-safe access
Inc/HALAL/Models/Packets/OrderProtocol.hpp	Adds virtual destructor to the base interface class

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