Add data exchange between websocket server and client to the websocket_client example

examples/websocket_client/websocket_client.c

@@ -21,7 +21,17 @@
 #define PORT "8888"
 #define SSL_CERT "./ssl/server.pem"
 
+const char * websocket_welcome_msg = "websocket welcome\n";
+const size_t websocket_welcome_msg_len = 18 /* strlen(websocket_welcome_msg) */ ;
+const char * websocket_acknowledge_msg = "websocket msg ok\n";
+const size_t websocket_acknowledge_msg_len = 17 /* strlen(websocket_acknowledge_msg) */ ;
+const char * websocket_goodbye_msg = "websocket bye\n";
+const size_t websocket_goodbye_msg_len = 14 /* strlen(websocket_goodbye_msg) */ ;
 
+
+/*************************************************************************************/
+/* WEBSOCKET SERVER                                                                  */
+/*************************************************************************************/
 int websock_server_connect(const struct mg_connection * conn)
 {
     printf("Server: Websocket connected\n");
@@ -31,25 +41,45 @@ int websock_server_connect(const struct mg_connection * conn)
 void websocket_server_ready(struct mg_connection * conn)
 {
     printf("Server: Websocket ready\n");
+
+    /* Send websocket welcome message */
+    mg_lock_connection(conn);
+    mg_websocket_write(conn, WEBSOCKET_OPCODE_TEXT, websocket_welcome_msg, websocket_welcome_msg_len);
+    mg_unlock_connection(conn);
 }
 
 int websocket_server_data(struct mg_connection * conn, int bits, char *data, size_t data_len)
 {
     printf("Server: Got %u bytes from the client\n", data_len);
+
+    if (data_len<3 || 0!=memcmp(data, "bye", 3)) {
+        /* Send websocket acknowledge message */
+        mg_lock_connection(conn);
+        mg_websocket_write(conn, WEBSOCKET_OPCODE_TEXT, websocket_acknowledge_msg, websocket_acknowledge_msg_len);
+        mg_unlock_connection(conn);
+    } else {
+        /* Send websocket acknowledge message */
+        mg_lock_connection(conn);
+        mg_websocket_write(conn, WEBSOCKET_OPCODE_TEXT, websocket_goodbye_msg, websocket_goodbye_msg_len);
+        mg_unlock_connection(conn);
+    }
+
     return 1; /* return 1 to keep the connetion open */
 }
 
 void websocket_server_connection_close(struct mg_connection * conn)
 {
     printf("Server: Close connection\n");
+
+    /* Can not send a websocket goodbye message here - the connection is already closed */
 }
 
 struct mg_context * start_websocket_server()
 {
     const char * options[] = { "document_root", DOCUMENT_ROOT,
-                               "ssl_certificate", SSL_CERT,
-                               "listening_ports", PORT, 0
-                             };
+        "ssl_certificate", SSL_CERT,
+        "listening_ports", PORT, 0
+    };
     struct mg_callbacks callbacks;
     struct mg_context *ctx;
 
@@ -64,12 +94,26 @@ struct mg_context * start_websocket_server()
 }
 
 
+/*************************************************************************************/
+/* WEBSOCKET CLIENT                                                                  */
+/*************************************************************************************/
+struct {
+    void * data;
+    size_t len;
+} client_data;
+
 static int websocket_client_data_handler(struct mg_connection *conn, int flags, char *data, size_t data_len)
 {
     printf("From server: ");
     fwrite(data, 1, data_len, stdout);
     printf("\n");
 
+    /* TODO: extra arg (instead of global client_data) */
+    client_data.data = malloc(data_len);
+    assert(client_data.data != NULL);
+    memcpy(client_data.data, data, data_len);
+    client_data.len = data_len;
+
     return 1;
 }
 
@@ -80,13 +124,16 @@ int main(int argc, char *argv[])
     struct mg_connection* newconn;
     char ebuf[100];
 
+    assert(websocket_welcome_msg_len == strlen(websocket_welcome_msg));
+
     /* First set up a websocket server */
     ctx = start_websocket_server();
     assert(ctx != NULL);
 
+    /* Then connect a client */
     newconn = mg_websocket_client_connect("localhost", atoi(PORT), 0,
-                             ebuf, sizeof(ebuf),
-                             "/websocket", NULL, websocket_client_data_handler);
+        ebuf, sizeof(ebuf),
+        "/websocket", NULL, websocket_client_data_handler /* TODO: extra arg (instead of global client_data) */);
 
     if (newconn == NULL)
     {
@@ -94,27 +141,52 @@ int main(int argc, char *argv[])
         return 1;
     }
 
+    sleep(1); /* Should get the websocket welcome message */
+    assert(client_data.data != NULL);
+    assert(client_data.len == websocket_welcome_msg_len);
+    assert(!memcmp(client_data.data, websocket_welcome_msg, websocket_welcome_msg_len));
+    free(client_data.data);
+    client_data.data = NULL;
+    client_data.len = 0;
+
     mg_websocket_write(newconn, WEBSOCKET_OPCODE_TEXT, "data1", 5);
 
-    sleep(1);
+    sleep(1); /* Should get the acknowledge message */
+    assert(client_data.data != NULL);
+    assert(client_data.len == websocket_acknowledge_msg_len);
+    assert(!memcmp(client_data.data, websocket_acknowledge_msg, websocket_acknowledge_msg_len));
+    free(client_data.data);
+    client_data.data = NULL;
+    client_data.len = 0;
 
     mg_websocket_write(newconn, WEBSOCKET_OPCODE_TEXT, "data2", 5);
 
-    sleep(1);
+    sleep(1); /* Should get the acknowledge message */
+    assert(client_data.data != NULL);
+    assert(client_data.len == websocket_acknowledge_msg_len);
+    assert(!memcmp(client_data.data, websocket_acknowledge_msg, websocket_acknowledge_msg_len));
+    free(client_data.data);
+    client_data.data = NULL;
+    client_data.len = 0;
 
-    mg_websocket_write(newconn, WEBSOCKET_OPCODE_TEXT, "data3", 5);
+    mg_websocket_write(newconn, WEBSOCKET_OPCODE_TEXT, "bye", 3);
 
-    sleep(1);
-
-    mg_websocket_write(newconn, WEBSOCKET_OPCODE_TEXT, "data4", 5);
-
-    sleep(1);
+    sleep(1); /* Should get the goodbye message */
+    assert(client_data.data != NULL);
+    assert(client_data.len == websocket_goodbye_msg_len);
+    assert(!memcmp(client_data.data, websocket_goodbye_msg, websocket_goodbye_msg_len));
+    free(client_data.data);
+    client_data.data = NULL;
+    client_data.len = 0;
 
     mg_close_connection(newconn);
 
+    sleep(1); /* Won't get any message */
+
     mg_stop(ctx);
+    printf("Server shutdown\n");
 
-    printf("Bye!\n");
+    sleep(10);
 
     return 0;
 }