GitHub - wolfSSL/wolfip: Lightweight TCP/IP stack with no dynamic memory allocations

wolfIP is a lightweight TCP/IP stack from wolfSSL designed for resource-constrained embedded systems. It avoids dynamic memory allocation entirely, using fixed socket counts and pre-allocated static buffers. The stack supports a comprehensive set of protocols including IPv4, TCP (with SACK, congestion control, timestamps), UDP, ICMP, IPsec ESP, DHCP, DNS, and HTTP/HTTPS via wolfSSL TLS. A BSD-like non-blocking socket API is provided. Testing is supported via LD_PRELOAD injection using a POSIX shim that redirects socket calls to the wolfIP stack over a TAP device. A FreeRTOS port is also included, using a background polling task with mutex-serialized stack access and callback-driven blocking operations.