Github user JPercivall commented on a diff in the pull request:
https://github.com/apache/nifi/pull/483#discussion_r70261777
--- Diff:
nifi-nar-bundles/nifi-email-bundle/nifi-email-processors/src/main/java/org/apache/nifi/processors/email/smtp/handler/SMTPMessageHandlerFactory.java
---
@@ -0,0 +1,147 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF 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.nifi.processors.email.smtp.handler;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.security.cert.X509Certificate;
+import java.util.concurrent.LinkedBlockingQueue;
+import java.util.concurrent.TimeUnit;
+
+import org.apache.nifi.logging.ComponentLog;
+import org.apache.nifi.stream.io.ByteArrayOutputStream;
+import org.apache.nifi.util.StopWatch;
+import org.subethamail.smtp.DropConnectionException;
+import org.subethamail.smtp.MessageContext;
+import org.subethamail.smtp.MessageHandler;
+import org.subethamail.smtp.MessageHandlerFactory;
+import org.subethamail.smtp.RejectException;
+import org.subethamail.smtp.TooMuchDataException;
+import org.subethamail.smtp.server.SMTPServer;
+
+import org.apache.nifi.processors.email.smtp.event.SmtpEvent;
+
+
+public class SMTPMessageHandlerFactory implements MessageHandlerFactory {
+ final LinkedBlockingQueue<SmtpEvent> incomingMessages;
+ final ComponentLog logger;
+
+ public SMTPMessageHandlerFactory(LinkedBlockingQueue<SmtpEvent>
incomingMessages, ComponentLog logger) {
+ this.incomingMessages = incomingMessages;
+ this.logger = logger;
+ }
+
+ @Override
+ public MessageHandler create(MessageContext messageContext) {
+ return new Handler(messageContext, incomingMessages, logger);
+ }
+
+ class Handler implements MessageHandler {
+ final MessageContext messageContext;
+ String from;
+ String recipient;
+ byte [] messageBody;
+
+
+ public Handler(MessageContext messageContext,
LinkedBlockingQueue<SmtpEvent> incomingMessages, ComponentLog logger){
+ this.messageContext = messageContext;
+ }
+
+ @Override
+ public void from(String from) throws RejectException {
+ // TODO: possibly whitelist senders?
+ this.from = from;
+ }
+
+ @Override
+ public void recipient(String recipient) throws RejectException {
+ // TODO: possibly whitelist receivers?
+ this.recipient = recipient;
+ }
+
+ @Override
+ public void data(InputStream inputStream) throws RejectException,
TooMuchDataException, IOException {
+ // Start counting the timer...
+
+ StopWatch watch = new StopWatch(false);
+
+ SMTPServer server = messageContext.getSMTPServer();
+
+ ByteArrayOutputStream baos = new ByteArrayOutputStream();
+
+ byte [] buffer = new byte[1024];
+ int rd;
+
+ while ((rd = inputStream.read(buffer, 0, buffer.length)) !=
-1) {
+ baos.write(buffer, 0, rd);
+ }
+ if (baos.getBufferLength() > server.getMaxMessageSize()) {
+ throw new TooMuchDataException("Data exceeds the amount
allowed.");
+ }
+
+ baos.flush();
+ this.messageBody = baos.toByteArray();
+
+
+ X509Certificate[] certificates = new X509Certificate[]{};
+
+ String remoteIP = messageContext.getRemoteAddress().toString();
+ String helo = messageContext.getHelo();
+ if (messageContext.getTlsPeerCertificates() != null ){
+ certificates = (X509Certificate[])
messageContext.getTlsPeerCertificates().clone();
+ }
+
+ SmtpEvent message = new SmtpEvent(remoteIP, helo, from,
recipient, certificates, messageBody);
+ try {
+ // Try to queue the message back to the NiFi session
+ incomingMessages.put(message);
+ } catch (InterruptedException e) {
+ // Throws an error to the incoming server alerting about
issues queuing the message in NiFi
+ logger.error("Hit an error sending message back to NiFi
main thread {}. Sending and error back to SMTP client and discarding message",
new Object [] {e});
+ throw new DropConnectionException(451, "NiFi something
went wrong while processing you message, please retry again later");
+ }
+
+ // Once message has been sent to the queue, it should be
processed by NiFi onTrigger,
+ // a flowfile created and its processed status updated before
an acknowledgment is
+ // given back to the SMTP client
+ try {
+ synchronized(message) {
+ while(! message.getProcessed()) {
+ // Check to see if it is too late...
+ final long serverTimeout =
TimeUnit.NANOSECONDS.convert(messageContext.getSMTPServer().getConnectionTimeout(),
TimeUnit.MILLISECONDS);
+ if ( watch.getElapsed(TimeUnit.MILLISECONDS) <=
serverTimeout) {
+ // Will should allow for a couple of retries;
--- End diff --
How is this retrying? From what I can tell, after the message is
put/offered to the queue, the OnTrigger will take it off and if it fails it
just hangs in limbo (until the server timeout happens).
You could probably go one of two routes:
1: No retries, after the message is taken off the queue the processor
attempts to process it. If it fails, the server doesn't try to reprocess it and
replies with a 451. To do this, you should add a flag to SmtpEvent with a
failure flag/string to convey that the message failed to process. That way you
can fail fast (instead of timing out).
2: Retries, the processor "peeks" at the queue instead of taking messages
off of it. Then once it has processed the message it removes it from the queue.
This would require a lock over the queue and for the processor to trigger
serially and probably changes in other places as well. This is how ConsumeMQTT
works.
I like option 1, it doesn't require significantly changing your code and
easily fits with the SMTP protocol.
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