Improve networking (#7)

* Support get/set for flags on socket fds
* Changes to support open62541 client/server
* Fix mismatch of enum sizes between WASM and host
* Improve zephyr sockets
* Add explanation comment

---------

Signed-off-by: Dan Kouba <dan@atym.io>
Signed-off-by: Krisztian Szilvasi <34309983+kr-t@users.noreply.github.com>
Co-authored-by: Dan Kouba <dan@atym.io>

Author: 2 people

core/shared/platform/zephyr/zephyr_file.c

@@ -15,6 +15,9 @@
 #include <zephyr/fs/fs_sys.h>
 #include <zephyr/fs/littlefs.h>
 
+#include <zephyr/net/socket.h>
+#include <zephyr/posix/fcntl.h> // F_GETFL, F_SETFL, O_NONBLOCK
+
 /* Notes:
  * This is the implementation of a POSIX-like file system interface for Zephyr.
  * To manage our file descriptors, we created a struct `zephyr_fs_desc` that
@@ -275,6 +278,16 @@ os_file_get_fdflags(os_file_handle handle, __wasi_fdflags_t *flags)
 {
     struct zephyr_fs_desc *ptr = NULL;
 
+    /* Sockets: reflect current non-blocking state */
+    if (handle->is_sock) {
+        int cur = zsock_fcntl(handle->fd, F_GETFL, 0);
+        if (cur < 0)
+            return convert_errno(errno);
+        if (cur & O_NONBLOCK)
+            *flags |= __WASI_FDFLAG_NONBLOCK;
+        return __WASI_ESUCCESS;
+    }
+
     if (os_is_virtual_fd(handle->fd)) {
         *flags = 0;
         return __WASI_ESUCCESS;
@@ -298,6 +311,21 @@ os_file_get_fdflags(os_file_handle handle, __wasi_fdflags_t *flags)
 __wasi_errno_t
 os_file_set_fdflags(os_file_handle handle, __wasi_fdflags_t flags)
 {
+    /* Sockets: set/clear O_NONBLOCK */
+    if (handle->is_sock) {
+        int cur = zsock_fcntl(handle->fd, F_GETFL, 0);
+        if (cur < 0)
+            return convert_errno(errno);
+
+        bool want_nb = (flags & __WASI_FDFLAG_NONBLOCK) != 0;
+        int newf = want_nb ? (cur | O_NONBLOCK) : (cur & ~O_NONBLOCK);
+
+        if (zsock_fcntl(handle->fd, F_SETFL, newf) < 0) {
+            return convert_errno(errno);
+        }
+        return __WASI_ESUCCESS;
+    }
+
     if (os_is_virtual_fd(handle->fd)) {
         return __WASI_ESUCCESS;
     }

core/shared/platform/zephyr/zephyr_socket.c

@@ -22,17 +22,23 @@ static bool
 textual_addr_to_sockaddr(const char *textual, int port, struct sockaddr *out,
                          socklen_t *out_len)
 {
-    struct sockaddr_in *v4;
+    struct sockaddr_in *v4 = (struct sockaddr_in *)out;
 #ifdef IPPROTO_IPV6
     struct sockaddr_in6 *v6;
 #endif
 
     assert(textual);
 
-    v4 = (struct sockaddr_in *)out;
     if (zsock_inet_pton(AF_INET, textual, &v4->sin_addr.s_addr) == 1) {
         v4->sin_family = AF_INET;
         v4->sin_port = htons(port);
+        /**
+         * In `zephyr_socket.c` the method `textual_addr_to_sockaddr` takes the
+         * multicast address of "224.0.0.22" and properly sets the sockaddr.
+         * However, this fails when binding to the adapter for some reason.
+         * Setting this to “0.0.0.0” works. This appears to be a bug in Zephyr.
+         */
+        v4->sin_addr.s_addr = htonl(INADDR_ANY);
         *out_len = sizeof(struct sockaddr_in);
         return true;
     }
@@ -923,10 +929,23 @@ os_socket_set_ip_add_membership(bh_socket_t socket,
         mreq.imr_multiaddr.s_addr = imr_multiaddr->ipv4;
         mreq.imr_address.s_addr = imr_interface;
 
-        if (zsock_setsockopt(socket->fd, IPPROTO_IP, IP_ADD_MEMBERSHIP, &mreq,
-                             sizeof(mreq))
-            != 0) {
-            return BHT_ERROR;
+        int ret = zsock_setsockopt(socket->fd, IPPROTO_IP, IP_ADD_MEMBERSHIP,
+                                   &mreq, sizeof(mreq));
+        if (ret != 0) {
+            /* Treat certain errors as non-fatal for multicast membership.
+             * These conditions indicate the operation is either already
+             * complete or not supported by the network stack, but shouldn't
+             * prevent the application from continuing. This improves
+             * compatibility across different Zephyr network configurations. */
+            switch (errno) {
+                case EALREADY:    /* already joined: OK */
+                case EADDRINUSE:  /* duplicate membership: OK */
+                case ENOPROTOOPT: /* option not supported: treat as soft-OK */
+                case ENOSYS:      /* not implemented: soft-OK */
+                    return BHT_OK;
+                default:
+                    return BHT_ERROR;
+            }
         }
     }
     return BHT_OK;
@@ -964,10 +983,23 @@ os_socket_set_ip_drop_membership(bh_socket_t socket,
         mreq.imr_multiaddr.s_addr = imr_multiaddr->ipv4;
         mreq.imr_address.s_addr = imr_interface;
 
-        if (zsock_setsockopt(socket->fd, IPPROTO_IP, IP_DROP_MEMBERSHIP, &mreq,
-                             sizeof(mreq))
-            != 0) {
-            return BHT_ERROR;
+        int ret = zsock_setsockopt(socket->fd, IPPROTO_IP, IP_ADD_MEMBERSHIP,
+                                   &mreq, sizeof(mreq));
+        if (ret != 0) {
+            /* Treat certain errors as non-fatal for multicast membership.
+             * These conditions indicate the operation is either already
+             * complete or not supported by the network stack, but shouldn't
+             * prevent the application from continuing. This improves
+             * compatibility across different Zephyr network configurations. */
+            switch (errno) {
+                case EALREADY:    /* already joined: OK */
+                case EADDRINUSE:  /* duplicate membership: OK */
+                case ENOPROTOOPT: /* option not supported: treat as soft-OK */
+                case ENOSYS:      /* not implemented: soft-OK */
+                    return BHT_OK;
+                default:
+                    return BHT_ERROR;
+            }
         }
     }
     return BHT_OK;