ws_client: added subprotocol configuration option to websocket client

closes https://github.com/espressif/esp-idf/issues/3893

components/esp_websocket_client/esp_websocket_client.c

@@ -62,6 +62,7 @@ typedef struct {
     bool                        auto_reconnect;
     void                        *user_context;
     int                         network_timeout_ms;
+    char                        *subprotocol;
 } websocket_config_storage_t;
 
 typedef enum {
@@ -173,6 +174,11 @@ static esp_err_t esp_websocket_client_set_config(esp_websocket_client_handle_t c
         cfg->path = strdup(config->path);
         ESP_WS_CLIENT_MEM_CHECK(TAG, cfg->path, return ESP_ERR_NO_MEM);
     }
+    if (config->subprotocol) {
+        free(cfg->subprotocol);
+        cfg->subprotocol = strdup(config->subprotocol);
+        ESP_WS_CLIENT_MEM_CHECK(TAG, cfg->subprotocol, return ESP_ERR_NO_MEM);
+    }
 
     cfg->network_timeout_ms = WEBSOCKET_NETWORK_TIMEOUT_MS;
     cfg->user_context = config->user_context;
@@ -200,21 +206,20 @@ static esp_err_t esp_websocket_client_destroy_config(esp_websocket_client_handle
     free(cfg->scheme);
     free(cfg->username);
     free(cfg->password);
+    free(cfg->subprotocol);
     memset(cfg, 0, sizeof(websocket_config_storage_t));
     free(client->config);
     client->config = NULL;
     return ESP_OK;
 }
 
-static void set_websocket_client_path(esp_websocket_client_handle_t client)
+static void set_websocket_transport_optional_settings(esp_websocket_client_handle_t client, esp_transport_handle_t trans)
 {
-    esp_transport_handle_t trans = esp_transport_list_get_transport(client->transport_list, "ws");
-    if (trans) {
+    if (trans && client->config->path) {
         esp_transport_ws_set_path(trans, client->config->path);
     }
-    trans = esp_transport_list_get_transport(client->transport_list, "wss");
-    if (trans) {
-        esp_transport_ws_set_path(trans, client->config->path);
+    if (trans && client->config->subprotocol) {
+        esp_transport_ws_set_subprotocol(trans, client->config->subprotocol);
     }
 }
 
@@ -297,9 +302,8 @@ esp_websocket_client_handle_t esp_websocket_client_init(const esp_websocket_clie
         ESP_WS_CLIENT_MEM_CHECK(TAG, client->config->scheme, goto _websocket_init_fail);
     }
 
-    if (client->config->path) {
-        set_websocket_client_path(client);
-    }
+    set_websocket_transport_optional_settings(client, esp_transport_list_get_transport(client->transport_list, "ws"));
+    set_websocket_transport_optional_settings(client, esp_transport_list_get_transport(client->transport_list, "wss"));
 
     client->keepalive_tick_ms = _tick_get_ms();
     client->reconnect_tick_ms = _tick_get_ms();
@@ -390,7 +394,6 @@ esp_err_t esp_websocket_client_set_uri(esp_websocket_client_handle_t client, con
                     puri.field_data[UF_QUERY].len, uri + puri.field_data[UF_QUERY].off);
         }
         ESP_WS_CLIENT_MEM_CHECK(TAG, client->config->path, return ESP_ERR_NO_MEM);
-        set_websocket_client_path(client);
     }
     if (puri.field_data[UF_PORT].off) {
         client->config->port = strtol((const char*)(uri + puri.field_data[UF_PORT].off), NULL, 10);

components/esp_websocket_client/include/esp_websocket_client.h

@@ -92,6 +92,7 @@ typedef struct {
     int                         buffer_size;                /*!< Websocket buffer size */
     const char                  *cert_pem;                  /*!< SSL Certification, PEM format as string, if the client requires to verify server */
     esp_websocket_transport_t   transport;                  /*!< Websocket transport type, see `esp_websocket_transport_t */
+    char                        *subprotocol;               /*!< Websocket subprotocol */
 } esp_websocket_client_config_t;
 
 /**