net: socket: syscall for socketpair(2)

Working:

* non-blocking reads / writes
* blocking reads / writes
* send(2) / recv(2) / sendto(2) / recvfrom(2) / sendmsg(2)
* select(2)
* poll(2)

Fixes #24366

Signed-off-by: Christopher Friedt <chrisfriedt@gmail.com>

CODEOWNERS

@@ -457,6 +457,7 @@
 /subsys/net/lib/config/                   @jukkar @tbursztyka @pfalcon
 /subsys/net/lib/mqtt/                     @jukkar @tbursztyka @rlubos
 /subsys/net/lib/coap/                     @rveerama1
+/subsys/net/lib/sockets/socketpair.c      @cfriedt
 /subsys/net/lib/sockets/                  @jukkar @tbursztyka @pfalcon
 /subsys/net/lib/tls_credentials/          @rlubos
 /subsys/net/l2/                           @jukkar @tbursztyka

include/net/net_ip.h

@@ -45,6 +45,8 @@ extern "C" {
 #define PF_PACKET       3          /**< Packet family.                */
 #define PF_CAN          4          /**< Controller Area Network.      */
 #define PF_NET_MGMT     5          /**< Network management info.      */
+#define PF_LOCAL        6          /**< Inter-process communication   */
+#define PF_UNIX         PF_LOCAL   /**< Inter-process communication   */
 
 /* Address families. */
 #define AF_UNSPEC      PF_UNSPEC   /**< Unspecified address family.   */
@@ -53,6 +55,8 @@ extern "C" {
 #define AF_PACKET      PF_PACKET   /**< Packet family.                */
 #define AF_CAN         PF_CAN      /**< Controller Area Network.      */
 #define AF_NET_MGMT    PF_NET_MGMT /**< Network management info.      */
+#define AF_LOCAL       PF_LOCAL    /**< Inter-process communication   */
+#define AF_UNIX        PF_UNIX     /**< Inter-process communication   */
 
 /** Protocol numbers from IANA/BSD */
 enum net_ip_protocol {
@@ -341,6 +345,12 @@ struct sockaddr_storage {
 	char data[NET_SOCKADDR_MAX_SIZE - sizeof(sa_family_t)];
 };
 
+/* Socket address struct for UNIX domain sockets */
+struct sockaddr_un {
+	sa_family_t sun_family;    /* AF_UNIX */
+	char        sun_path[NET_SOCKADDR_MAX_SIZE - sizeof(sa_family_t)];
+};
+
 struct net_addr {
 	sa_family_t family;
 	union {

include/net/socket.h

@@ -159,6 +159,20 @@ struct zsock_addrinfo {
  */
 __syscall int zsock_socket(int family, int type, int proto);
 
+/**
+ * @brief Create an unnamed pair of connected sockets
+ *
+ * @details
+ * @rst
+ * See `POSIX.1-2017 article
+ * <https://pubs.opengroup.org/onlinepubs/009695399/functions/socketpair.html>`__
+ * for normative description.
+ * This function is also exposed as ``socketpair()``
+ * if :option:`CONFIG_NET_SOCKETS_POSIX_NAMES` is defined.
+ * @endrst
+ */
+__syscall int zsock_socketpair(int family, int type, int proto, int *sv);
+
 /**
  * @brief Close a network socket
  *
@@ -566,6 +580,11 @@ static inline int socket(int family, int type, int proto)
 	return zsock_socket(family, type, proto);
 }
 
+static inline int socketpair(int family, int type, int proto, int sv[2])
+{
+	return zsock_socketpair(family, type, proto, sv);
+}
+
 static inline int close(int sock)
 {
 	return zsock_close(sock);

include/posix/sys/socket.h

@@ -18,6 +18,11 @@ static inline int socket(int family, int type, int proto)
 	return zsock_socket(family, type, proto);
 }
 
+static inline int socketpair(int family, int type, int proto, int sv[2])
+{
+	return zsock_socketpair(family, type, proto, sv);
+}
+
 #define SHUT_RD ZSOCK_SHUT_RD
 #define SHUT_WR ZSOCK_SHUT_WR
 #define SHUT_RDWR ZSOCK_SHUT_RDWR

subsys/net/lib/sockets/CMakeLists.txt

@@ -28,4 +28,6 @@ if(CONFIG_SOCKS)
   zephyr_include_directories(${ZEPHYR_BASE}/subsys/net/lib/socks)
 endif()
 
+zephyr_sources_ifdef(CONFIG_NET_SOCKETPAIR socketpair.c)
+
 zephyr_link_libraries_ifdef(CONFIG_MBEDTLS mbedTLS)

subsys/net/lib/sockets/Kconfig

@@ -139,6 +139,21 @@ config NET_SOCKETS_CAN_RECEIVERS
 	  The value tells how many sockets can receive data from same
 	  Socket-CAN interface.
 
+config NET_SOCKETPAIR
+	bool "Support for the socketpair syscall [EXPERIMENTAL]"
+	depends on HEAP_MEM_POOL_SIZE != 0
+	help
+	  Choose y here if you would like to use the socketpair(2)
+	  system call.
+
+config NET_SOCKETPAIR_BUFFER_SIZE
+	int "Size of the intermediate buffer, in bytes"
+	default 64
+	range 1 4096
+	depends on NET_SOCKETPAIR
+	help
+	  Buffer size for socketpair(2)
+
 config NET_SOCKETS_NET_MGMT
 	bool "Enable network management socket support [EXPERIMENTAL]"
 	depends on NET_MGMT_EVENT