Merge branch 'feature/alpn_support' into 'master'

Add support for ALPN

See merge request espressif/esp-mqtt!46

include/mqtt_client.h

@@ -167,6 +167,7 @@ typedef struct {
     const struct psk_key_hint* psk_hint_key;     /*!< Pointer to PSK struct defined in esp_tls.h to enable PSK authentication (as alternative to certificate verification). If not NULL and server/client certificates are NULL, PSK is enabled */
     bool          use_global_ca_store;      /*!< Use a global ca_store for all the connections in which this bool is set. */
     int reconnect_timeout_ms;               /*!< Reconnect to the broker after this value in miliseconds if auto reconnect is not disabled */
+    const char **alpn_protos;               /*!< NULL-terminated list of supported application protocols to be used for ALPN */
 } esp_mqtt_client_config_t;
 
 /**

include/mqtt_supported_features.h

@@ -43,6 +43,7 @@
 // Features supported in 4.1
 #define MQTT_SUPPORTED_FEATURE_PSK_AUTHENTICATION
 #define MQTT_SUPPORTED_FEATURE_DER_CERTIFICATES
+#define MQTT_SUPPORTED_FEATURE_ALPN
 #endif
 #endif
 

mqtt_client.c

@@ -78,6 +78,8 @@ typedef struct {
     int network_timeout_ms;
     int refresh_connection_after_ms;
     int reconnect_timeout_ms;
+    char **alpn_protos;
+    int num_alpn_protos;
 } mqtt_config_storage_t;
 
 typedef enum {
@@ -253,6 +255,28 @@ esp_err_t esp_mqtt_set_config(esp_mqtt_client_handle_t client, const esp_mqtt_cl
         cfg->reconnect_timeout_ms = MQTT_RECON_DEFAULT_MS;
     }
 
+    if(config->alpn_protos) {
+        for (int i = 0; i < cfg->num_alpn_protos; i++) {
+            free(cfg->alpn_protos[i]);
+        }
+        free(cfg->alpn_protos);
+        cfg->num_alpn_protos = 0;
+
+        const char **p;
+
+        for (p = config->alpn_protos; *p != NULL; p++ ) {
+            cfg->num_alpn_protos++;
+        }
+        // mbedTLS expects the list to be null-terminated
+        cfg->alpn_protos = calloc(cfg->num_alpn_protos + 1, sizeof(config->alpn_protos));
+        ESP_MEM_CHECK(TAG, cfg->alpn_protos, goto _mqtt_set_config_failed);
+
+        for (int i = 0; i < cfg->num_alpn_protos; i++) {
+            cfg->alpn_protos[i] = strdup(config->alpn_protos[i]);
+            ESP_MEM_CHECK(TAG, cfg->alpn_protos[i], goto _mqtt_set_config_failed);
+        }
+    }
+
     MQTT_API_UNLOCK_FROM_OTHER_TASK(client);
     return ESP_OK;
 _mqtt_set_config_failed:
@@ -268,6 +292,10 @@ static esp_err_t esp_mqtt_destroy_config(esp_mqtt_client_handle_t client)
     free(cfg->uri);
     free(cfg->path);
     free(cfg->scheme);
+    for (int i = 0; i < cfg->num_alpn_protos; i++) {
+            free(cfg->alpn_protos[i]);
+    }
+    free(cfg->alpn_protos);
     memset(cfg, 0, sizeof(mqtt_config_storage_t));
     free(client->connect_info.will_topic);
     free(client->connect_info.will_message);
@@ -447,6 +475,16 @@ esp_mqtt_client_handle_t esp_mqtt_client_init(const esp_mqtt_client_config_t *co
         goto _mqtt_init_failed;
 #endif
     }
+
+    if (client->config->alpn_protos) {
+#ifdef MQTT_SUPPORTED_FEATURE_ALPN
+        esp_transport_ssl_set_alpn_protocol(ssl, (const char **)client->config->alpn_protos);
+#else
+        ESP_LOGE(TAG, "APLN is not available in IDF version %s", IDF_VER);
+        goto _mqtt_init_failed;
+#endif
+    }
+
     esp_transport_list_add(client->transport_list, ssl, "mqtts");
     if (config->transport == MQTT_TRANSPORT_OVER_SSL) {
         client->config->scheme = create_string("mqtts", 5);