esp-protocols/components/sock_utils/README.md

Socket Utilities

This component provides simplified implementations of common socket-related utilities using lwIP and esp_netif. It is especially useful for porting Linux-based libraries to ESP32 where performance and memory constraints are secondary considerations.

Supported Functions

API	Description	Limitations	Declared in
ifaddrs()	Retrieves interface addresses using esp_netif	IPv4 addresses only	ifaddrs.h
socketpair() *)	Creates a pair of connected sockets using lwIP loopback stream sockets	IPv4 sockets only	socketpair.h, sys/socket.h **)
pipe() *)	Wraps socketpair() to provide unidirectional pipe-like functionality	Uses bidirectional sockets in place of true pipes	socketpair.h, unistd.h ***)
getnameinfo()	Converts IP addresses to human-readable form using lwIP's inet_ntop()	IPv4 only; supports NI_NUMERICHOST and NI_NUMERICSERV flags only	getnameinfo.h, netdb.h in ESP-IDF
gai_strerror()	Returns error code as a string	Simple numeric string representation only	gai_strerror.h, netdb.h **)
gethostname()	Returns lwip netif hostname	Not a system-wide hostname, but interface specific hostname	gethostname.h, unistd.h in ESP-IDF

Notes:

• *) socketpair() and pipe() are built on top of lwIP TCP sockets, inheriting the same characteristics. For instance, the maximum transmit buffer size is based on the TCP_SND_BUF setting.
• **) socketpair() and gai_strerror() are declared in sock_utils header files, the declaration is propagated to ESP-IDF from v5.5 to the official header files. If you're using older IDF version, you need to manually pre-include related header files from the sock_utils public include directory.
• ***) pipe() is declared in compiler's sys/unistd.h.