net/nanocoap: Send separate response from server socket

This makes sure the separate response is send using the network
interface the request was received on.

Author: maribu

sys/Makefile.dep

@@ -539,7 +539,6 @@ endif
 
 ifneq (,$(filter nanocoap_server_separate,$(USEMODULE)))
   USEMODULE += nanocoap_server
-  USEMODULE += sock_aux_local
 endif
 
 ifneq (,$(filter nanocoap_server_tcp,$(USEMODULE)))

sys/include/net/nanocoap.h

@@ -560,6 +560,7 @@ struct _coap_request_ctx {
                 sock_udp_ep_t *local;           /**< deprecated alias for local_udp */
             };
 #  endif
+            sock_udp_t *sock_udp;       /** UDP socket the request was received on */
         };
 #endif
 #if MODULE_NANOCOAP_TCP

sys/include/net/nanocoap_sock.h

@@ -299,7 +299,10 @@ typedef struct {
 #if MODULE_NANOCOAP_UDP || MODULE_NANOCOAP_DTLS || DOXYGEN
         struct {
             sock_udp_ep_t remote_udp;       /**< UDP endpoint to send response to */
-            sock_udp_ep_t local_udp;        /**< UDP endpoint from which to send response */
+#  if MODULE_SOCK_AUX_LOCAL
+            sock_udp_ep_t local_udp;        /**< UDP endpoint to send response from */
+#  endif
+            sock_udp_t *sock_udp;           /**< UDP socket to send from */
         };
 #endif
 #if MODULE_NANOCOAP_SERVER_TCP || DOXYGEN

sys/net/application_layer/nanocoap/sock.c

@@ -2096,7 +2096,8 @@ int nanocoap_server_udp(sock_udp_ep_t *local, void *rsp_buf, size_t rsp_buf_len)
     sock_udp_t sock;
     sock_udp_ep_t remote;
     coap_request_ctx_t ctx = {
-        .remote = &remote,
+        .remote_udp = &remote,
+        .sock_udp = &sock,
     };
 
     if (!local->port) {
@@ -2189,8 +2190,10 @@ int nanocoap_server_prepare_separate(nanocoap_server_response_ctx_t *ctx,
 #if MODULE_NANOCOAP_UDP
     case COAP_TRANSPORT_UDP:
         memcpy(&ctx->remote_udp, req->remote_udp, sizeof(ctx->remote_udp));
-        assert(req->local);
+#    if MODULE_SOCK_AUX_LOCAL
         memcpy(&ctx->local_udp, req->local_udp, sizeof(ctx->local_udp));
+#    endif
+        ctx->sock_udp = req->sock_udp;
         break;
 #endif
 #if MODULE_NANOCOAP_SERVER_TCP
@@ -2268,6 +2271,7 @@ static int _nanocoap_server_sendv_separate_udp(const nanocoap_server_response_ct
                                                const iolist_t *reply)
 {
     sock_udp_aux_tx_t *aux_out_ptr = NULL;
+#    if MODULE_SOCK_AUX_LOCAL
     /* make sure we reply with the same address that the request was
      * destined for -- except in the multicast case */
     sock_udp_aux_tx_t aux_out = {
@@ -2277,12 +2281,15 @@ static int _nanocoap_server_sendv_separate_udp(const nanocoap_server_response_ct
     if (!sock_udp_ep_is_multicast(&ctx->local_udp)) {
         aux_out_ptr = &aux_out;
     }
-    ssize_t retval = sock_udp_sendv_aux(NULL, reply, &ctx->remote_udp, aux_out_ptr);
+#    endif
+    ssize_t retval = sock_udp_sendv_aux(ctx->sock_udp, reply, &ctx->remote_udp, aux_out_ptr);
 
     if (retval < 0) {
         return retval;
     }
 
+    DEBUG("nanocoap: Sent %u B of separate response\n", (unsigned)retval);
+
     return 0;
 }
 #  endif