net: http_server: Add support for generic HTTP2 500 response

In case of errors during HTTP2 request processing (or after the HTTP1
upgrade response was sent), send 500 Internal Server Error response
before shutting down the connection.

Signed-off-by: Robert Lubos <[email protected]>

Author: rlubos

subsys/net/lib/http/http_server_http2.c

@@ -369,6 +369,46 @@ static int send_http2_409(struct http_client_ctx *client,
 	return ret;
 }
 
+static void send_http2_500(struct http_client_ctx *client,
+			   struct http2_frame *frame, int error_code)
+{
+#define HTTP_500_RESPONSE_TEMPLATE "Internal Server Error%s%s"
+#define MAX_ERROR_DESC_LEN 32
+
+	char error_str[] = "xxx";
+	char http_response[sizeof(HTTP_500_RESPONSE_TEMPLATE) +
+			   MAX_ERROR_DESC_LEN + 1]; /* For the error description */
+	const char *error_desc;
+	const char *desc_separator;
+
+	if (IS_ENABLED(CONFIG_HTTP_SERVER_REPORT_FAILURE_REASON)) {
+		/* Try to fetch error description, fallback to error number if
+		 * not available
+		 */
+		error_desc = strerror(error_code);
+		if (strlen(error_desc) == 0) {
+			/* Cast error value to uint8_t to avoid truncation warnings. */
+			(void)snprintk(error_str, sizeof(error_str), "%u",
+				       (uint8_t)error_code);
+			error_desc = error_str;
+		}
+		desc_separator = ": ";
+	} else {
+		error_desc = "";
+		desc_separator = "";
+	}
+
+	if (send_headers_frame(client, HTTP_500_INTERNAL_SERVER_ERROR,
+			       frame->stream_identifier, NULL, 0, NULL, 0) < 0) {
+		return;
+	}
+
+	(void)snprintk(http_response, sizeof(http_response),
+		       HTTP_500_RESPONSE_TEMPLATE, desc_separator, error_desc);
+	(void)send_data_frame(client, http_response, strlen(http_response),
+			      frame->stream_identifier, HTTP2_FLAG_END_STREAM);
+}
+
 static int handle_http2_static_resource(
 	struct http_resource_detail_static *static_detail,
 	struct http2_frame *frame, struct http_client_ctx *client)
@@ -1027,7 +1067,7 @@ int handle_http1_to_http2_upgrade(struct http_client_ctx *client)
 		ret = http_server_sendall(client, switching_protocols,
 					  sizeof(switching_protocols) - 1);
 		if (ret < 0) {
-			goto error;
+			return ret;
 		}
 
 		client->http1_headers_sent = true;
@@ -1101,6 +1141,11 @@ int handle_http1_to_http2_upgrade(struct http_client_ctx *client)
 	return 0;
 
 error:
+	if (ret != -EAGAIN && client->current_stream &&
+	    !client->current_stream->headers_sent) {
+		send_http2_500(client, frame, -ret);
+	}
+
 	return ret;
 }
 
@@ -1169,13 +1214,14 @@ int handle_http_frame_data(struct http_client_ctx *client)
 		/* There is no handler */
 		LOG_DBG("No dynamic handler found.");
 		(void)send_http2_404(client, frame);
-		return -ENOENT;
+		ret = -ENOENT;
+		goto error;
 	}
 
 	if (is_header_flag_set(frame->flags, HTTP2_FLAG_PADDED)) {
 		ret = parse_http_frame_padded_field(client);
 		if (ret < 0) {
-			return ret;
+			goto error;
 		}
 	}
 
@@ -1187,7 +1233,7 @@ int handle_http_frame_data(struct http_client_ctx *client)
 	}
 
 	if (ret < 0) {
-		return ret;
+		goto error;
 	}
 
 	if (frame->length == 0) {
@@ -1197,17 +1243,18 @@ int handle_http_frame_data(struct http_client_ctx *client)
 		if (stream == NULL) {
 			LOG_DBG("No stream context found for ID %d",
 				frame->stream_identifier);
-			return -EBADMSG;
+			ret = -EBADMSG;
+			goto error;
 		}
 
 		ret = send_window_update_frame(client, stream);
 		if (ret < 0) {
-			return ret;
+			goto error;
 		}
 
 		ret = send_window_update_frame(client, NULL);
 		if (ret < 0) {
-			return ret;
+			goto error;
 		}
 
 		if (is_header_flag_set(frame->flags, HTTP2_FLAG_END_STREAM)) {
@@ -1224,6 +1271,14 @@ int handle_http_frame_data(struct http_client_ctx *client)
 	}
 
 	return 0;
+
+error:
+	if (ret != -EAGAIN && client->current_stream &&
+	    !client->current_stream->headers_sent) {
+		send_http2_500(client, frame, -ret);
+	}
+
+	return ret;
 }
 
 static void check_user_request_headers_http2(struct http_header_capture_ctx *ctx,
@@ -1473,14 +1528,14 @@ int handle_http_frame_headers(struct http_client_ctx *client)
 	if (is_header_flag_set(frame->flags, HTTP2_FLAG_PADDED)) {
 		ret = parse_http_frame_padded_field(client);
 		if (ret < 0) {
-			return ret;
+			goto error;
 		}
 	}
 
 	if (is_header_flag_set(frame->flags, HTTP2_FLAG_PRIORITY)) {
 		ret = parse_http_frame_priority_field(client);
 		if (ret < 0) {
-			return ret;
+			goto error;
 		}
 	}
 
@@ -1496,12 +1551,17 @@ int handle_http_frame_headers(struct http_client_ctx *client)
 				ret = -EBADMSG;
 			}
 
-			return ret;
+			if (ret < 0) {
+				goto error;
+			}
+
+			return 0;
 		}
 
 		if (ret > frame->length) {
 			LOG_ERR("Protocol error, frame length exceeded");
-			return -EBADMSG;
+			ret = -EBADMSG;
+			goto error;
 		}
 
 		frame->length -= ret;
@@ -1513,7 +1573,7 @@ int handle_http_frame_headers(struct http_client_ctx *client)
 
 		ret = process_header(client, header);
 		if (ret < 0) {
-			return ret;
+			goto error;
 		}
 	}
 
@@ -1532,34 +1592,34 @@ int handle_http_frame_headers(struct http_client_ctx *client)
 				(struct http_resource_detail_static *)detail,
 				frame, client);
 			if (ret < 0) {
-				return ret;
+				goto error;
 			}
 		} else if (detail->type == HTTP_RESOURCE_TYPE_STATIC_FS) {
 			ret = handle_http2_static_fs_resource(
 				(struct http_resource_detail_static_fs *)detail, frame, client);
 			if (ret < 0) {
-				return ret;
+				goto error;
 			}
 		} else if (detail->type == HTTP_RESOURCE_TYPE_DYNAMIC) {
 			ret = handle_http2_dynamic_resource(
 				(struct http_resource_detail_dynamic *)detail,
 				frame, client);
 			if (ret < 0) {
-				return ret;
+				goto error;
 			}
 		}
 
 	} else {
 		ret = send_http2_404(client, frame);
 		if (ret < 0) {
-			return ret;
+			goto error;
 		}
 	}
 
 	if (is_header_flag_set(frame->flags, HTTP2_FLAG_END_STREAM)) {
 		ret = handle_http_frame_headers_end_stream(client);
 		if (ret < 0) {
-			return ret;
+			goto error;
 		}
 	}
 
@@ -1570,6 +1630,14 @@ int handle_http_frame_headers(struct http_client_ctx *client)
 	}
 
 	return 0;
+
+error:
+	if (ret != -EAGAIN && client->current_stream &&
+	    !client->current_stream->headers_sent) {
+		send_http2_500(client, frame, -ret);
+	}
+
+	return ret;
 }
 
 int handle_http_frame_priority(struct http_client_ctx *client)