pipewire: add PW_KEY_SEC_SOCKET and set it in protocol

Add client key PW_KEY_SEC_SOCKET that indicates which socket the client used
to connect to the server.

This can be used by other modules as an access control mechanism.

src/modules/module-protocol-native.c

@@ -578,6 +578,8 @@ static struct client_data *client_new(struct server *s, int fd)
 	if (props == NULL)
 		goto exit;
 
+	pw_properties_set(props, PW_KEY_SEC_SOCKET, s->socket_info.name);
+
 #if defined(__linux__)
 	len = sizeof(ucred);
 	if (getsockopt(fd, SOL_SOCKET, SO_PEERCRED, &ucred, &len) < 0) {

src/pipewire/impl-client.c

@@ -524,6 +524,7 @@ int pw_impl_client_register(struct pw_impl_client *client,
 		PW_KEY_SEC_UID,
 		PW_KEY_SEC_GID,
 		PW_KEY_SEC_LABEL,
+		PW_KEY_SEC_SOCKET,
 		NULL
 	};
 

src/pipewire/keys.h

@@ -38,6 +38,8 @@ extern "C" {
 #define PW_KEY_SEC_GID			"pipewire.sec.gid"	/**< client gid, set by protocol*/
 #define PW_KEY_SEC_LABEL		"pipewire.sec.label"	/**< client security label, set by protocol*/
 
+#define PW_KEY_SEC_SOCKET		"pipewire.sec.socket"	/**< client socket name, set by protocol */
+
 #define PW_KEY_LIBRARY_NAME_SYSTEM	"library.name.system"	/**< name of the system library to use */
 #define PW_KEY_LIBRARY_NAME_LOOP	"library.name.loop"	/**< name of the loop library to use */
 #define PW_KEY_LIBRARY_NAME_DBUS	"library.name.dbus"	/**< name of the dbus library to use */