net: sockets: Add a way to register a socket family handler

Allow automatic handling of registered socket families.

Signed-off-by: Jukka Rissanen <jukka.rissanen@linux.intel.com>

include/linker/common-rom.ld

@@ -67,6 +67,16 @@
 		__net_l2_end = .;
 	} GROUP_LINK_IN(ROMABLE_REGION)
 
+#if defined(CONFIG_NET_SOCKETS)
+	SECTION_PROLOGUE(net_socket_register,,)
+	{
+		__net_socket_register_start = .;
+		*(".net_socket_register.init")
+		KEEP(*(SORT_BY_NAME(".net_socket_register.init*")))
+		__net_socket_register_end = .;
+	} GROUP_LINK_IN(ROMABLE_REGION)
+#endif
+
 	SECTION_DATA_PROLOGUE(_bt_services_area,,SUBALIGN(4))
 	{
 		_bt_services_start = .;

include/net/socket.h

@@ -719,6 +719,30 @@ static inline char *inet_ntop(sa_family_t family, const void *src, char *dst,
 /** sockopt: Don't support IPv4 access (ignored, for compatibility) */
 #define IPV6_V6ONLY 26
 
+/** @cond INTERNAL_HIDDEN */
+/**
+ * @brief Registration information for a given BSD socket family.
+ */
+struct net_socket_register {
+	int family;
+	bool (*is_supported)(int family, int type, int proto);
+	int (*handler)(int family, int type, int proto);
+};
+
+#define NET_SOCKET_GET_NAME(socket_name)	\
+	(__net_socket_register_##socket_name)
+
+#define NET_SOCKET_REGISTER(socket_name, _family, _is_supported, _handler) \
+	static const struct net_socket_register				\
+			(NET_SOCKET_GET_NAME(socket_name)) __used	\
+	__attribute__((__section__(".net_socket_register.init"))) = {	\
+		.family = _family,					\
+		.is_supported = _is_supported,				\
+		.handler = _handler,					\
+	}
+
+/** @endcond */
+
 #ifdef __cplusplus
 }
 #endif

scripts/sanitycheck

@@ -896,7 +896,8 @@ class SizeCalculator:
     # These get copied into RAM only on non-XIP
     ro_sections = ["text", "ctors", "init_array", "reset", "object_access",
                    "rodata", "devconfig", "net_l2", "vector", "sw_isr_table",
-                   "_bt_settings_area", "_bt_services_area", "vectors"]
+                   "_bt_settings_area", "_bt_services_area", "vectors",
+                   "net_socket_register"]
 
     def __init__(self, filename, extra_sections):
         """Constructor

subsys/net/lib/sockets/sockets.c

@@ -20,6 +20,9 @@ LOG_MODULE_REGISTER(net_sock, CONFIG_NET_SOCKETS_LOG_LEVEL);
 
 #include "sockets_internal.h"
 
+extern struct net_socket_register __net_socket_register_start[];
+extern struct net_socket_register __net_socket_register_end[];
+
 #define SET_ERRNO(x) \
 	{ int _err = x; if (_err < 0) { errno = -_err; return -1; } }
 
@@ -129,6 +132,25 @@ int zsock_socket_internal(int family, int type, int proto)
 
 int z_impl_zsock_socket(int family, int type, int proto)
 {
+	struct net_socket_register *sock_family;
+
+	for (sock_family = __net_socket_register_start;
+	     sock_family != __net_socket_register_end;
+	     sock_family++) {
+		if (sock_family->family != family &&
+		    sock_family->family != AF_UNSPEC) {
+			continue;
+		}
+
+		NET_ASSERT(sock_family->is_supported);
+
+		if (!sock_family->is_supported(family, type, proto)) {
+			continue;
+		}
+
+		return sock_family->handler(family, type, proto);
+	}
+
 #if defined(CONFIG_NET_SOCKETS_SOCKOPT_TLS)
 	if (((proto >= IPPROTO_TLS_1_0) && (proto <= IPPROTO_TLS_1_2)) ||
 	    (proto >= IPPROTO_DTLS_1_0 && proto <= IPPROTO_DTLS_1_2)) {