Github user trixpan commented on a diff in the pull request:
https://github.com/apache/nifi/pull/827#discussion_r74362397
--- Diff:
nifi-nar-bundles/nifi-email-bundle/nifi-email-processors/src/main/java/org/apache/nifi/processors/email/ListenSMTP.java
---
@@ -13,89 +13,52 @@
* 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;
-import javax.net.ssl.SSLContext;
-import javax.net.ssl.SSLSocket;
-import javax.net.ssl.SSLSocketFactory;
import java.io.IOException;
-import java.io.InputStream;
+import java.io.OutputStream;
import java.net.InetSocketAddress;
import java.net.Socket;
import java.util.ArrayList;
-import java.util.Collection;
import java.util.Collections;
-import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
-import java.util.Map;
import java.util.Set;
-import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.TimeUnit;
-import java.util.concurrent.atomic.AtomicBoolean;
-
-import org.apache.commons.lang3.StringUtils;
-
-import org.subethamail.smtp.server.SMTPServer;
-
-
-import org.apache.nifi.annotation.lifecycle.OnStopped;
-import org.apache.nifi.annotation.lifecycle.OnUnscheduled;
-import org.apache.nifi.flowfile.attributes.CoreAttributes;
-import org.apache.nifi.processor.DataUnit;
+import java.util.concurrent.atomic.AtomicInteger;
-import org.apache.nifi.annotation.lifecycle.OnScheduled;
-import org.apache.nifi.components.PropertyDescriptor;
-import org.apache.nifi.processor.AbstractProcessor;
-import org.apache.nifi.processor.ProcessorInitializationContext;
-import org.apache.nifi.processor.Relationship;
-import org.apache.nifi.processor.util.StandardValidators;
+import javax.net.ssl.SSLContext;
+import javax.net.ssl.SSLSocket;
+import javax.net.ssl.SSLSocketFactory;
+import org.apache.commons.io.IOUtils;
import org.apache.nifi.annotation.behavior.InputRequirement;
-import org.apache.nifi.annotation.behavior.WritesAttribute;
-import org.apache.nifi.annotation.behavior.WritesAttributes;
import org.apache.nifi.annotation.documentation.CapabilityDescription;
import org.apache.nifi.annotation.documentation.Tags;
+import org.apache.nifi.annotation.lifecycle.OnStopped;
+import org.apache.nifi.components.PropertyDescriptor;
+import org.apache.nifi.flowfile.FlowFile;
+import org.apache.nifi.processor.AbstractSessionFactoryProcessor;
+import org.apache.nifi.processor.DataUnit;
import org.apache.nifi.processor.ProcessContext;
import org.apache.nifi.processor.ProcessSession;
+import org.apache.nifi.processor.ProcessSessionFactory;
+import org.apache.nifi.processor.Relationship;
import org.apache.nifi.processor.exception.ProcessException;
-import org.apache.nifi.components.ValidationContext;
-import org.apache.nifi.components.ValidationResult;
-import org.apache.nifi.flowfile.FlowFile;
+import org.apache.nifi.processor.io.OutputStreamCallback;
+import org.apache.nifi.processor.util.StandardValidators;
import org.apache.nifi.ssl.SSLContextService;
-
-import org.apache.nifi.processors.email.smtp.event.SmtpEvent;
-import org.apache.nifi.processors.email.smtp.handler.SMTPResultCode;
-import
org.apache.nifi.processors.email.smtp.handler.SMTPMessageHandlerFactory;
+import org.subethamail.smtp.server.SMTPServer;
@Tags({"listen", "email", "smtp"})
@InputRequirement(InputRequirement.Requirement.INPUT_FORBIDDEN)
-@CapabilityDescription("This processor implements a lightweight SMTP
server to an arbitrary port, " +
- "allowing nifi to listen for incoming email. " +
- "" +
- "Note this server does not perform any email validation. If direct
exposure to the internet is sought," +
- "it may be a better idea to use the combination of NiFi and an
industrial scale MTA (e.g. Postfix)")
-@WritesAttributes({
- @WritesAttribute(attribute = "mime.type", description = "The value
used during HELO"),
- @WritesAttribute(attribute = "smtp.helo", description = "The value
used during HELO"),
- @WritesAttribute(attribute = "smtp.certificates.*.serial",
description = "The serial numbers for each of the " +
- "certificates used by an TLS peer"),
- @WritesAttribute(attribute = "smtp.certificates.*.principal",
description = "The principal for each of the " +
- "certificates used by an TLS peer"),
- @WritesAttribute(attribute = "smtp.from", description = "The value
used during MAIL FROM (i.e. envelope)"),
- @WritesAttribute(attribute = "smtp.to", description = "The value
used during RCPT TO (i.e. envelope)"),
- @WritesAttribute(attribute = "smtp.src", description = "The source
IP of the SMTP connection")})
--- End diff --
@olegz
I remember that conversation, however this information cannot be derived
from downstream events as they are not part of the message but part of the SMTP
conversation.
I works like this:
```
$ telnet 0 2525
Trying 0.0.0.0...
Connected to 0.
Escape character is '^]'.
220 localhost ESMTP Apache NiFi
helo .
250 localhost
mail from: [email protected]
250 Ok
rcpt to: [email protected]
250 Ok
data
354 End data with <CR><LF>.<CR><LF>
From: [email protected]
To: [email protected]
Subject: Some relevant data was missed in here
Don't you think?
.
250 Ok
quit
221 Bye
Connection closed by foreign host.
```
Results in:

```
Received: from . (localhost [127.0.0.1])
by localhost
with SMTP (Apache NiFi) id IRPNED6Q
for [email protected];
Thu, 11 Aug 2016 11:30:51 +1000 (AEST)
From: [email protected]
To: [email protected]
Subject: Some relevant data was missed in here
Don't you think?
```
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