coap: Update examples to use latest features of libcoap component

Support libcoap build with Client Only or Server Only code.

examples/protocols/coap_client/README.md

@@ -18,8 +18,6 @@ CoAP server needs to know about.
 
 If the URI is prefixed with coap+tcp://, then the CoAP will try to use TCP for the communication.
 
-NOTE: coaps+tcp:// is not currently supported, even though both libcoap and MbedTLS support it.
-
 The Constrained Application Protocol (CoAP) is a specialized web transfer protocol for use with
 constrained nodes and constrained networks in the Internet of Things.
 The protocol is designed for machine-to-machine (M2M) applications such as smart energy and
@@ -36,18 +34,18 @@ idf.py menuconfig
 ```
 
 Example Connection Configuration  --->
- * Set WiFi SSID under Example Configuration
- * Set WiFi Password under Example Configuration
-Example CoAP Client Configuration  --->
- * Set CoAP Target Uri
- * If PSK, Set CoAP Preshared Key to use in connection to the server
- * If PSK, Set CoAP PSK Client identity (username)
+ * Set WiFi SSID
+ * Set WiFi Password
 Component config  --->
   CoAP Configuration  --->
     * Set encryption method definition, PSK (default) or PKI
     * Enable CoAP debugging if required
-  High resolution timer (esp_timer)  --->
-    * Hardware timer to use for esp_timer - change if required (FRC2 for QEMU)
+    * Disable CoAP using TCP if this is not required (TCP needed for TLS)
+    * Disable CoAP server functionality to reduce code size
+Example CoAP Client Configuration  --->
+ * Set CoAP Target Uri
+ * If PSK, Set CoAP Preshared Key to use in connection to the server
+ * If PSK, Set CoAP PSK Client identity (username)
 
 ### Build and Flash
 
@@ -103,8 +101,9 @@ These can be raised at [libcoap Issues](https://github.com/obgm/libcoap/issues).
 
 ## Troubleshooting
 * Please make sure Target Url includes valid `host`, optional `port`,
-optional `path`, and begins with `coap://`, `coaps://` or `coap+tcp://`
-for a coap server that supports TCP
-(not all do including coap+tcp://californium.eclipseprojects.io).
+optional `path`, and begins with `coap://`, `coaps://`, `coap+tcp://` or `coaps+tcp://`
+(not all hosts support TCP/TLS including coap+tcp://californium.eclipseprojects.io).
 
-* CoAP logging can be enabled by running 'idf.py menuconfig -> Component config -> CoAP Configuration' and setting appropriate log level
+* CoAP logging can be enabled by running 'idf.py menuconfig -> Component config -> CoAP Configuration -> Enable CoAP debugging'
+and setting appropriate log level.  If Mbed TLS logging is required, this needs to be configured separately under mbedTLS
+Component Configuration and the CoAP logging level set to mbedTLS.

examples/protocols/coap_client/main/coap_client_example_main.c

@@ -33,6 +33,11 @@
 
 #include "coap3/coap.h"
 
+
+#ifndef CONFIG_COAP_CLIENT_SUPPORT
+#error COAP_CLIENT_SUPPORT needs to be enabled
+#endif /* COAP_CLIENT_SUPPORT */
+
 #define COAP_DEFAULT_TIME_SEC 60
 
 /* The examples use simple Pre-Shared-Key configuration that you can set via
@@ -224,11 +229,15 @@ coap_build_optlist(coap_uri_t *uri)
     optlist = NULL;
 
     if (uri->scheme == COAP_URI_SCHEME_COAPS && !coap_dtls_is_supported()) {
-        ESP_LOGE(TAG, "MbedTLS (D)TLS Client Mode not configured");
+        ESP_LOGE(TAG, "MbedTLS DTLS Client Mode not configured");
         return 0;
     }
     if (uri->scheme == COAP_URI_SCHEME_COAPS_TCP && !coap_tls_is_supported()) {
-        ESP_LOGE(TAG, "CoAP server uri->+tcp:// scheme is not supported");
+        ESP_LOGE(TAG, "MbedTLS TLS Client Mode not configured");
+        return 0;
+    }
+    if (uri->scheme == COAP_URI_SCHEME_COAP_TCP && !coap_tcp_is_supported()) {
+        ESP_LOGE(TAG, "TCP Client Mode not configured");
         return 0;
     }
 
@@ -389,10 +398,6 @@ static void coap_example_client(void *p)
     /*
      * Note that if the URI starts with just coap:// (not coaps://) the
      * session will still be plain text.
-     *
-     * coaps+tcp:// is NOT yet supported by the libcoap->mbedtls interface
-     * so COAP_URI_SCHEME_COAPS_TCP will have failed in a test above,
-     * but the code is left in for completeness.
      */
     if (uri.scheme == COAP_URI_SCHEME_COAPS || uri.scheme == COAP_URI_SCHEME_COAPS_TCP) {
 #ifndef CONFIG_MBEDTLS_TLS_CLIENT

examples/protocols/coap_client/sdkconfig.defaults

@@ -2,3 +2,4 @@ CONFIG_MBEDTLS_SSL_PROTO_DTLS=y
 CONFIG_MBEDTLS_PSK_MODES=y
 CONFIG_MBEDTLS_KEY_EXCHANGE_PSK=y
 CONFIG_LWIP_NETBUF_RECVINFO=y
+CONFIG_COAP_CLIENT_SUPPORT=y

examples/protocols/coap_server/README.md

@@ -16,9 +16,6 @@ try to establish a DTLS session using the previously defined Pre-Shared Key (PSK
 must be the same as the one that the CoAP client is using, or Public Key Infrastructure (PKI) where
 the PKI information must match as requested.
 
-NOTE: Client sessions trying to use coaps+tcp:// are not currently supported, even though both
-libcoap and MbedTLS support it.
-
 The Constrained Application Protocol (CoAP) is a specialized web transfer protocol for use with
 constrained nodes and constrained networks in the Internet of Things.
 The protocol is designed for machine-to-machine (M2M) applications such as smart energy and
@@ -35,17 +32,16 @@ idf.py menuconfig
 ```
 
 Example Connection Configuration  --->
- * Set WiFi SSID under Example Configuration
- * Set WiFi Password under Example Configuration
-Example CoAP Client Configuration  --->
- * If PSK, Set CoAP Preshared Key to use in connection to the server
+ * Set WiFi SSID
+ * Set WiFi Password
 Component config  --->
   CoAP Configuration  --->
     * Set encryption method definition, PSK (default) or PKI
     * Enable CoAP debugging if required
-  High resolution timer (esp_timer)  --->
-    * Hardware timer to use for esp_timer - change if required (FRC2 for QEMU)
-
+    * Disable CoAP using TCP if this is not required (TCP needed for TLS)
+    * Disable CoAP client functionality to reduce code size unless this server is a proxy
+Example CoAP Server Configuration  --->
+ * If PSK, Set CoAP Preshared Key to use for connections to the server
 
 ### Build and Flash
 
@@ -93,4 +89,6 @@ These can be raised at [libcoap Issues](https://github.com/obgm/libcoap/issues).
 * Please make sure CoAP client fetchs or puts data under path: `/Espressif` or
 fetches `/.well-known/core`
 
-* CoAP logging can be enabled by running 'idf.py menuconfig -> Component config -> CoAP Configuration' and setting appropriate log level
+* CoAP logging can be enabled by running 'idf.py menuconfig -> Component config -> CoAP Configuration -> Enable CoAP debugging'
+and setting appropriate log level.  If Mbed TLS logging is required, this needs to be configured separately under mbedTLS
+Component Configuration and the CoAP logging level set to mbedTLS.

examples/protocols/coap_server/main/coap_server_example_main.c

@@ -31,6 +31,10 @@
 
 #include "coap3/coap.h"
 
+#ifndef CONFIG_COAP_SERVER_SUPPORT
+#error COAP_SERVER_SUPPORT needs to be enabled
+#endif /* COAP_SERVER_SUPPORT */
+
 /* The examples use simple Pre-Shared-Key configuration that you can set via
    'idf.py menuconfig'.
 
@@ -187,6 +191,7 @@ static void coap_example_server(void *p)
     while (1) {
         coap_endpoint_t *ep = NULL;
         unsigned wait_ms;
+        int have_dtls = 0;
 
         /* Prepare the CoAP server socket */
         coap_address_init(&serv_addr);
@@ -258,16 +263,18 @@ static void coap_example_server(void *p)
             ESP_LOGE(TAG, "udp: coap_new_endpoint() failed");
             goto clean_up;
         }
-        ep = coap_new_endpoint(ctx, &serv_addr, COAP_PROTO_TCP);
-        if (!ep) {
-            ESP_LOGE(TAG, "tcp: coap_new_endpoint() failed");
-            goto clean_up;
+        if (coap_tcp_is_supported()) {
+            ep = coap_new_endpoint(ctx, &serv_addr, COAP_PROTO_TCP);
+            if (!ep) {
+                ESP_LOGE(TAG, "tcp: coap_new_endpoint() failed");
+                goto clean_up;
+            }
         }
 #if defined(CONFIG_COAP_MBEDTLS_PSK) || defined(CONFIG_COAP_MBEDTLS_PKI)
         if (coap_dtls_is_supported()) {
 #ifndef CONFIG_MBEDTLS_TLS_SERVER
             /* This is not critical as unencrypted support is still available */
-            ESP_LOGI(TAG, "MbedTLS (D)TLS Server Mode not configured");
+            ESP_LOGI(TAG, "MbedTLS DTLS Server Mode not configured");
 #else /* CONFIG_MBEDTLS_TLS_SERVER */
             serv_addr.addr.sin6.sin6_port = htons(COAPS_DEFAULT_PORT);
             ep = coap_new_endpoint(ctx, &serv_addr, COAP_PROTO_DTLS);
@@ -275,8 +282,23 @@ static void coap_example_server(void *p)
                 ESP_LOGE(TAG, "dtls: coap_new_endpoint() failed");
                 goto clean_up;
             }
+            have_dtls = 1;
 #endif /* CONFIG_MBEDTLS_TLS_SERVER */
-        } else {
+        }
+        if (coap_tls_is_supported()) {
+#ifndef CONFIG_MBEDTLS_TLS_SERVER
+            /* This is not critical as unencrypted support is still available */
+            ESP_LOGI(TAG, "MbedTLS TLS Server Mode not configured");
+#else /* CONFIG_MBEDTLS_TLS_SERVER */
+            serv_addr.addr.sin6.sin6_port = htons(COAPS_DEFAULT_PORT);
+            ep = coap_new_endpoint(ctx, &serv_addr, COAP_PROTO_TLS);
+            if (!ep) {
+                ESP_LOGE(TAG, "tls: coap_new_endpoint() failed");
+                goto clean_up;
+            }
+#endif /* CONFIG_MBEDTLS_TLS_SERVER */
+        }
+        if (!have_dtls) {
             /* This is not critical as unencrypted support is still available */
             ESP_LOGI(TAG, "MbedTLS (D)TLS Server Mode not configured");
         }

examples/protocols/coap_server/sdkconfig.defaults

@@ -2,3 +2,4 @@ CONFIG_MBEDTLS_SSL_PROTO_DTLS=y
 CONFIG_MBEDTLS_PSK_MODES=y
 CONFIG_MBEDTLS_KEY_EXCHANGE_PSK=y
 CONFIG_LWIP_NETBUF_RECVINFO=y
+CONFIG_COAP_SERVER_SUPPORT=y