# TargetRequestHandler.java

    /*
     *  Copyright (c) 2022, WSO2 Inc. (http://www.wso2.org) All Rights Reserved.
     *
     *  WSO2 Inc. licenses this file to you under the Apache License,
     *  Version 2.0 (the "License"); you may not use this file except
     *  in compliance with the License.
     *  You may obtain a copy of the License at
     *
     *  http://www.apache.org/licenses/LICENSE-2.0
     *
     *  Unless required by applicable law or agreed to in writing,
     *  software distributed under the License is distributed on an
     *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
     *  KIND, either express or implied.  See the License for the
     *  specific language governing permissions and limitations
     *  under the License.
     *
     */
    package org.apache.synapse.transport.netty.sender;

    import io.netty.handler.codec.http.DefaultHttpRequest;
    import io.netty.handler.codec.http.HttpHeaderNames;
    import io.netty.handler.codec.http.HttpHeaders;
    import io.netty.handler.codec.http.HttpMethod;
    import io.netty.handler.codec.http.HttpVersion;
    import org.apache.axiom.om.OMOutputFormat;
    import org.apache.axis2.AxisFault;
    import org.apache.axis2.context.ConfigurationContext;
    import org.apache.axis2.context.MessageContext;
    import org.apache.axis2.transport.MessageFormatter;
    import org.apache.axis2.transport.http.HTTPConstants;
    import org.apache.axis2.transport.http.SOAPMessageFormatter;
    import org.apache.axis2.util.MessageProcessorSelector;
    import org.apache.commons.logging.Log;
    import org.apache.commons.logging.LogFactory;
    import org.apache.http.protocol.HTTP;
    import org.apache.synapse.transport.netty.BridgeConstants;
    import org.apache.synapse.transport.netty.config.NettyConfiguration;
    import org.apache.synapse.transport.netty.config.TargetConfiguration;
    import org.apache.synapse.transport.netty.util.HttpUtils;
    import org.apache.synapse.transport.netty.util.RequestResponseUtils;
    import org.apache.synapse.transport.nhttp.NhttpConstants;
    import org.apache.synapse.transport.nhttp.util.MessageFormatterDecoratorFactory;
    import org.apache.synapse.transport.passthru.PassThroughConstants;
    import org.apache.synapse.transport.passthru.util.PassThroughTransportUtils;
    import org.apache.synapse.transport.passthru.util.RelayUtils;
    import org.apache.synapse.transport.passthru.util.TargetRequestFactory;
    import org.wso2.transport.http.netty.contract.Constants;
    import org.wso2.transport.http.netty.contract.HttpClientConnector;
    import org.wso2.transport.http.netty.contract.HttpResponseFuture;
    import org.wso2.transport.http.netty.contract.HttpWsConnectorFactory;
    import org.wso2.transport.http.netty.contract.config.ChunkConfig;
    import org.wso2.transport.http.netty.contract.config.KeepAliveConfig;
    import org.wso2.transport.http.netty.contract.config.SenderConfiguration;
    import org.wso2.transport.http.netty.contractimpl.sender.channel.BootstrapConfiguration;
    import org.wso2.transport.http.netty.contractimpl.sender.channel.pool.ConnectionManager;
    import org.wso2.transport.http.netty.message.HttpCarbonMessage;
    import org.wso2.transport.http.netty.message.HttpMessageDataStreamer;

    import java.io.IOException;
    import java.io.OutputStream;
    import java.net.MalformedURLException;
    import java.net.URL;
    import java.util.Map;
    import java.util.Objects;

    /**
     * {@code TargetRequestHandler} have utilities for creating and preparing an outbound request to be sent
     * to the backend service.
     */
    public class TargetRequestHandler {

        private static final Log LOG = LogFactory.getLog(TargetRequestHandler.class);

        /**
         * Creates outbound request to be sent to the Backend service.
         *
         * @param url                 URL of the backend service
         * @param msgContext          axis2 message context
         * @param targetConfiguration configurations of the Transport Sender
         * @return the outbound request HttpCarbonMessage
         */
        public static HttpCarbonMessage createOutboundRequestMsg(URL url, MessageContext msgContext,
                                                                 TargetConfiguration targetConfiguration)
                throws AxisFault {

            HttpCarbonMessage outboundRequest =
                    new HttpCarbonMessage(new DefaultHttpRequest(new HttpVersion(BridgeConstants.HTTP_2_0, Boolean.TRUE),
                            HttpMethod.GET, ""));
            prepareOutboundRequest(url, outboundRequest, msgContext, targetConfiguration);
            return outboundRequest;
        }

        private static void prepareOutboundRequest(URL url, HttpCarbonMessage outboundRequest, MessageContext msgContext,
                                                   TargetConfiguration targetConfiguration) throws AxisFault {

            try {
                int port = getOutboundReqPort(url);
                String host = url.getHost();

                setOutboundReqProperties(outboundRequest, url, port, host, msgContext);
                setOutboundReqHeaders(outboundRequest, port, host, msgContext, targetConfiguration);

            } catch (MalformedURLException e) {
                RequestResponseUtils.handleException("Malformed URL in the target EPR.", e);
            } catch (IOException e) {
                RequestResponseUtils.handleException("Failed to prepare the outbound request.", e);
            }
        }

        private static void setOutboundReqProperties(HttpCarbonMessage outboundRequest, URL url, int port, String host,
                                                     MessageContext msgContext) throws IOException {

            setHTTPMethod(msgContext, outboundRequest);
            outboundRequest.setProperty(BridgeConstants.HTTP_HOST, host);
            outboundRequest.setProperty(BridgeConstants.HTTP_PORT, port);
            outboundRequest.setProperty(BridgeConstants.TO, getOutboundReqPath(url, msgContext));
            outboundRequest.setProperty(BridgeConstants.PROTOCOL, url.getProtocol());
            outboundRequest.setProperty(BridgeConstants.NO_ENTITY_BODY, HttpUtils.isNoEntityBodyRequest(msgContext));
        }

        private static void setOutboundReqHeaders(HttpCarbonMessage outboundRequest, int port, String host,
                                                  MessageContext msgContext, TargetConfiguration targetConfiguration)
                throws AxisFault {

            HttpHeaders headers = outboundRequest.getHeaders();
            HttpUtils.removeUnwantedHeadersFromInternalTransportHeadersMap(msgContext, targetConfiguration);
            HttpUtils.addTransportHeadersToTransportMessage(headers, msgContext);
            setContentTypeHeaderIfApplicable(msgContext, outboundRequest, targetConfiguration);
            setWSAActionIfApplicable(msgContext, headers);
            HttpUtils.setHostHeader(host, port, headers, msgContext,
                    targetConfiguration.isPreserveHttpHeader(HTTPConstants.HEADER_HOST));
            setOutboundUserAgent(headers);
        }

        private static void setHTTPMethod(MessageContext msgCtx, HttpCarbonMessage outboundRequest) {

            String httpMethod = (String) msgCtx.getProperty(BridgeConstants.HTTP_METHOD);
            if (Objects.isNull(httpMethod)) {
                httpMethod = HTTPConstants.HTTP_METHOD_POST;
            }
            outboundRequest.setHttpMethod(httpMethod);
        }

        private static int getOutboundReqPort(URL url) {

            int port = 80;
            if (url.getPort() != -1) {
                port = url.getPort();
            } else if (url.getProtocol().equalsIgnoreCase(Constants.HTTPS_SCHEME)) {
                port = 443;
            }
            return port;
        }

        private static String getOutboundReqPath(URL url, MessageContext msgCtx) throws IOException {

            if (HttpUtils.isGETRequest(msgCtx) || (RelayUtils.isDeleteRequestWithoutPayload(msgCtx))) {
                MessageFormatter formatter = MessageProcessorSelector.getMessageFormatter(msgCtx);
                OMOutputFormat format = PassThroughTransportUtils.getOMOutputFormat(msgCtx);

                if (formatter != null) {
                    URL targetURL = formatter.getTargetAddress(msgCtx, format, url);
                    if (targetURL != null && !targetURL.toString().isEmpty()) {
                        if (msgCtx.isPropertyTrue(BridgeConstants.POST_TO_URI)) {
                            return targetURL.toString();
                        } else {
                            return targetURL.getPath()
                                    + ((targetURL.getQuery() != null && !targetURL.getQuery().isEmpty())
                                    ? ("?" + targetURL.getQuery())
                                    : "");
                        }
                    }
                }
            }

            if (msgCtx.isPropertyTrue(BridgeConstants.POST_TO_URI)) {
                return url.toString();
            }

            // TODO: need to check "(route.getProxyHost() != null && !route.isTunnelled())" as well
            return msgCtx.isPropertyTrue(BridgeConstants.FULL_URI)
                    ? url.toString() : url.getPath() + (url.getQuery() != null ? "?" + url.getQuery() : "");
        }

        private static void setOutboundUserAgent(HttpHeaders headers) {

            if (!headers.contains(HttpHeaderNames.USER_AGENT)) {
                headers.set(HttpHeaderNames.USER_AGENT, BridgeConstants.DEFAULT_OUTBOUND_USER_AGENT);
            }
        }

        private static void setContentTypeHeaderIfApplicable(MessageContext msgCtx, HttpCarbonMessage outboundRequest,
                                                             TargetConfiguration targetConfiguration)
                throws AxisFault {

            Map transportHeaders = (Map) msgCtx.getProperty(MessageContext.TRANSPORT_HEADERS);

            if (transportHeaders != null) {
                String trpContentType = (String) transportHeaders.get(HTTP.CONTENT_TYPE);
                if (trpContentType != null && !trpContentType.equals("")) {
                    if (!TargetRequestFactory.isMultipartContent(trpContentType) && !msgCtx.isDoingSwA()) {
                        outboundRequest.setHeader(HTTP.CONTENT_TYPE, trpContentType);
                        return;
                    }
                }
            }

            String cType = getContentType(msgCtx,
                    targetConfiguration.isPreserveHttpHeader(HTTP.CONTENT_TYPE), transportHeaders);
            if (cType != null
                    && !HTTPConstants.HTTP_METHOD_GET.equals((String) msgCtx.getProperty(BridgeConstants.HTTP_METHOD))
                    && shouldOverwriteContentType(msgCtx, outboundRequest)) {
                String messageType = (String) msgCtx.getProperty(NhttpConstants.MESSAGE_TYPE);
                if (messageType != null) {
                    // if multipart related message type and unless if message
                    // not get build we should
                    // skip of setting formatter specific content Type
                    if (!messageType.contains(HTTPConstants.MEDIA_TYPE_MULTIPART_RELATED)
                            && !messageType.contains(HTTPConstants.MEDIA_TYPE_MULTIPART_FORM_DATA)) {
                        outboundRequest.setHeader(HTTP.CONTENT_TYPE, cType);
                    } else {
                        // if messageType is related to multipart and if message
                        // already built we need to set new
                        // boundary related content type at Content-Type header
                        boolean builderInvoked = Boolean.TRUE.equals(msgCtx
                                .getProperty(PassThroughConstants.MESSAGE_BUILDER_INVOKED));
                        if (builderInvoked) {
                            outboundRequest.setHeader(HTTP.CONTENT_TYPE, cType);
                        }
                    }
                } else {
                    outboundRequest.setHeader(HTTP.CONTENT_TYPE, cType);
                }
            }

            if ((PassThroughConstants.HTTP_GET.equals(msgCtx.getProperty(BridgeConstants.HTTP_METHOD))) ||
                    (RelayUtils.isDeleteRequestWithoutPayload(msgCtx))) {
                MessageFormatter formatter = MessageProcessorSelector.getMessageFormatter(msgCtx);
                if (formatter != null) {
                    outboundRequest.removeHeader(HTTP.CONTENT_TYPE);
                }
            }
        }

        public static String getContentType(MessageContext msgCtx, boolean isContentTypePreservedHeader,
                                            Map trpHeaders) throws AxisFault {

            String setEncoding = (String) msgCtx.getProperty(PassThroughConstants.SET_CHARACTER_ENCODING);

            // If incoming transport isn't HTTP, transport headers can be null. Therefore null check is required
            // and if headers not null check whether request comes with Content-Type header before preserving Content-Type
            // Need to avoid this for multipart headers, need to add MIME Boundary property
            if (trpHeaders != null
                    && (trpHeaders).get(HTTPConstants.HEADER_CONTENT_TYPE) != null
                    && (isContentTypePreservedHeader || PassThroughConstants.VALUE_FALSE.equals(setEncoding))
                    && !RequestResponseUtils.isMultipartContent((trpHeaders).get(HTTPConstants.HEADER_CONTENT_TYPE)
                    .toString())) {
                if (msgCtx.getProperty(org.apache.axis2.Constants.Configuration.CONTENT_TYPE) != null) {
                    return (String) msgCtx.getProperty(org.apache.axis2.Constants.Configuration.CONTENT_TYPE);
                } else if (msgCtx.getProperty(org.apache.axis2.Constants.Configuration.MESSAGE_TYPE) != null) {
                    return (String) msgCtx.getProperty(org.apache.axis2.Constants.Configuration.MESSAGE_TYPE);
                }
            }

            MessageFormatter formatter = MessageProcessorSelector.getMessageFormatter(msgCtx);
            OMOutputFormat format = PassThroughTransportUtils.getOMOutputFormat(msgCtx);

            if (formatter != null) {
                return formatter.getContentType(msgCtx, format, msgCtx.getSoapAction());

            } else {
                String contentType = (String) msgCtx.getProperty(org.apache.axis2.Constants.Configuration.CONTENT_TYPE);
                if (contentType != null) {
                    return contentType;
                } else {
                    return new SOAPMessageFormatter().getContentType(
                            msgCtx, format, msgCtx.getSoapAction());
                }
            }
        }

        /**
         * Check whether the we should overwrite the content type for the outgoing request.
         *
         * @param msgContext MessageContext
         * @return whether to overwrite the content type for the outgoing request
         */
        public static boolean shouldOverwriteContentType(MessageContext msgContext, HttpCarbonMessage outboundRequest) {

            boolean builderInvoked = Boolean.TRUE.equals(msgContext
                    .getProperty(PassThroughConstants.MESSAGE_BUILDER_INVOKED));
            boolean noEntityBodySet =
                    Boolean.TRUE.equals(msgContext.getProperty(PassThroughConstants.NO_ENTITY_BODY));

            // if contentTypeInRequest is true, that means it is set from the transport headers. that means the header
            // came in the source request.
            boolean contentTypeInRequest = outboundRequest.getHeader("Content-Type") != null
                    || outboundRequest.getHeader("content-type") != null;
            boolean isDefaultContentTypeEnabled = false;
            ConfigurationContext configurationContext = msgContext.getConfigurationContext();
            if (configurationContext != null && configurationContext.getAxisConfiguration()
                    .getParameter(NhttpConstants.REQUEST_CONTENT_TYPE) != null) {
                isDefaultContentTypeEnabled = true;
            }
            // If builder is not invoked, which means the passthrough scenario, we should overwrite the content-type
            // depending on the presence of the incoming content-type.
            // If builder is invoked and no entity body property is not set (which means there is a payload in the request)
            // we should consider overwriting the content-type.
            return (builderInvoked && !noEntityBodySet) || contentTypeInRequest || isDefaultContentTypeEnabled;
        }

        private static void setWSAActionIfApplicable(MessageContext msgCtx, HttpHeaders headers) {

            String soapAction = msgCtx.getSoapAction();
            if (soapAction == null) {
                soapAction = msgCtx.getWSAAction();
            }

            MessageFormatter messageFormatter =
                    MessageFormatterDecoratorFactory.createMessageFormatterDecorator(msgCtx);
            if (msgCtx.isSOAP11() && Objects.nonNull(soapAction) && !soapAction.isEmpty()
                    && Objects.nonNull(messageFormatter)) {
                headers.add(HTTPConstants.HEADER_SOAP_ACTION, messageFormatter.formatSOAPAction(msgCtx, null, soapAction));
            }
        }

        public static HttpClientConnector createHttpClient(URL url, MessageContext msgContext,
                                                           HttpWsConnectorFactory httpWsConnectorFactory,
                                                           ConnectionManager connectionManager,
                                                           BootstrapConfiguration bootstrapConfiguration,
                                                           TargetConfiguration targetConfiguration) throws AxisFault {

            try {
                SenderConfiguration senderConfiguration = new SenderConfiguration();
                populateSenderConfigurations(msgContext, senderConfiguration, targetConfiguration, url);

                return httpWsConnectorFactory.createHttpClientConnector(bootstrapConfiguration, senderConfiguration,
                        connectionManager);

            } catch (Exception ex) {
                throw new AxisFault("Error while creating the HTTP Client Connector. ", ex);
            }
        }

        public static void populateSenderConfigurations(MessageContext msgContext,
                                                        SenderConfiguration senderConfiguration,
                                                        TargetConfiguration targetConfiguration,
                                                        URL url) throws AxisFault {

            String scheme = url.getProtocol() != null ? url.getProtocol() : BridgeConstants.PROTOCOL_HTTP;
            senderConfiguration.setScheme(scheme);

            String httpVersion = BridgeConstants.HTTP_2_0_VERSION;
            String forceHttp10 = (String) msgContext.getProperty(PassThroughConstants.FORCE_HTTP_1_0);
            if (BridgeConstants.VALUE_TRUE.equalsIgnoreCase(forceHttp10)) {
                httpVersion = BridgeConstants.HTTP_1_0_VERSION;
            }
            senderConfiguration.setHttpVersion(httpVersion);

            if (isClientEndpointChunkingEnabled(msgContext)) {
                senderConfiguration.setChunkingConfig(ChunkConfig.ALWAYS);
            } else {
                senderConfiguration.setChunkingConfig(ChunkConfig.NEVER);
            }

            if (isClientEndpointKeepAliveDisabled(msgContext)) {
                senderConfiguration.setKeepAliveConfig(KeepAliveConfig.NEVER);
            } else {
                senderConfiguration.setKeepAliveConfig(KeepAliveConfig.ALWAYS);
            }

            senderConfiguration.setHttpTraceLogEnabled(targetConfiguration.isHttpTraceLogEnabled());

            // Set Request validation limits.
            boolean isRequestLimitsValidationEnabled = targetConfiguration.isRequestLimitsValidationEnabled();
            if (isRequestLimitsValidationEnabled) {
                RequestResponseUtils.setInboundMgsSizeValidationConfig(
                        targetConfiguration.getClientRequestMaxStatusLineLength(),
                        targetConfiguration.getClientRequestMaxHeaderSize(),
                        targetConfiguration.getClientRequestMaxEntityBodySize(),
                        senderConfiguration.getMsgSizeValidationConfig());
            }

            senderConfiguration.setSocketIdleTimeout(targetConfiguration.getSocketTimeout() * 1000);

            if (BridgeConstants.PROTOCOL_HTTPS.equals(scheme)) {
                targetConfiguration.getClientSSLConfigurationBuilder().setClientSSLConfig(senderConfiguration);
            }
        }

        private static boolean isClientEndpointChunkingEnabled(MessageContext msgContext) {

            if (msgContext.isPropertyTrue(NhttpConstants.FORCE_HTTP_CONTENT_LENGTH)) {
                return false;
            } else {
                String disableChunking = (String) msgContext.getProperty(PassThroughConstants.DISABLE_CHUNKING);
                return !BridgeConstants.VALUE_TRUE.equals(disableChunking)
                        && !BridgeConstants.VALUE_TRUE.equals(msgContext.getProperty(PassThroughConstants.FORCE_HTTP_1_0));
            }
        }

        private static boolean isClientEndpointKeepAliveDisabled(MessageContext msgContext) {

            String noKeepAliveProperty = (String) msgContext.getProperty(BridgeConstants.NO_KEEPALIVE);
            if (Objects.nonNull(noKeepAliveProperty)) {
                return msgContext.isPropertyTrue(noKeepAliveProperty);
            }

            Map transportHeaders = (Map) msgContext.getProperty(MessageContext.TRANSPORT_HEADERS);
            if (transportHeaders != null) {
                Object connectionHeader = transportHeaders.get(HTTP.CONN_DIRECTIVE);
                if (Objects.nonNull(connectionHeader) && "close".equalsIgnoreCase(connectionHeader.toString())) {
                    return true;
                }
            }

            return NettyConfiguration.getInstance().isKeepAliveDisabled();
        }

        public static void sendRequest(HttpClientConnector clientConnector, HttpCarbonMessage outboundRequestMsg,
                                       MessageContext msgContext, TargetConfiguration targetConfiguration)
                throws AxisFault {

            sendOutboundRequest(clientConnector, outboundRequestMsg, msgContext, targetConfiguration);
            serializeData(msgContext, outboundRequestMsg);
        }

        private static void sendOutboundRequest(HttpClientConnector clientConnector,
                                                HttpCarbonMessage outboundRequestMsg,
                                                MessageContext msgContext,
                                                TargetConfiguration targetConfiguration) {

            HttpResponseFuture future = clientConnector.send(outboundRequestMsg);
            future.setHttpConnectorListener(new Axis2HttpTargetRespListener(targetConfiguration.getWorkerPool(),
                    msgContext, targetConfiguration));

        }

        private static void serializeData(MessageContext msgCtx, HttpCarbonMessage responseMsg)
                throws AxisFault {

            if (ignoreMessageBody(msgCtx)) {
                OutputStream messageOutputStream = HttpUtils.getHttpMessageDataStreamer(responseMsg).getOutputStream();
                HttpUtils.writeEmptyBody(messageOutputStream);
            } else {
                if (RequestResponseUtils.shouldInvokeFormatterToWriteBody(msgCtx)) {
                    HttpMessageDataStreamer outboundMsgDataStreamer = HttpUtils.getHttpMessageDataStreamer(responseMsg);
                    OutputStream messageOutputStream = outboundMsgDataStreamer.getOutputStream();
                    MessageFormatter messageFormatter =
                            MessageFormatterDecoratorFactory.createMessageFormatterDecorator(msgCtx);
                    if (Objects.nonNull(messageFormatter)) {
                        HttpUtils.serializeDataUsingMessageFormatter(msgCtx, messageFormatter, messageOutputStream);
                    } else {
                        LOG.warn("Could not serialize the message. No available formatter to write the "
                                + "message to the backend.");
                    }
                } else {
                    HttpCarbonMessage inboundCarbonMessage =
                            (HttpCarbonMessage) msgCtx.getProperty(BridgeConstants.HTTP_CARBON_MESSAGE);
                    HttpUtils.copyContentFromInboundHttpCarbonMessage(inboundCarbonMessage, responseMsg);
                }
            }
        }

        /**
         * Checks if we can ignore the message body.
         *
         * @param msgContext axis2 message context
         * @return whether we can ignore the message body
         */
        private static boolean ignoreMessageBody(MessageContext msgContext) {

            return HttpUtils.isGETRequest(msgContext) || RelayUtils.isDeleteRequestWithoutPayload(msgContext);
        }
    }