# README
MailHog SMTP Protocol 
github.com/mailhog/smtp implements an SMTP server state machine.
It attempts to encapsulate as much of the SMTP protocol (plus its extensions) as possible without compromising configurability or requiring specific backend implementations.
proto := NewProtocol()
reply := proto.Start()
reply = proto.ProcessCommand("EHLO localhost")
// ...
See MailHog-Server and MailHog-MTA for example implementations.
Commands and replies
Interaction with the state machine is via:
- the
Parsefunction - the
ProcessCommandandProcessDatafunctions
You can mix the use of all three functions as necessary.
Parse
Parse should be used on a raw text stream. It looks for an end of line (\r\n), and if found, processes a single command. Any unprocessed data is returned.
If any unprocessed data is returned, Parse should be
called again to process then next command.
text := "EHLO localhost\r\nMAIL FROM:<test>\r\nDATA\r\nTest\r\n.\r\n"
var reply *smtp.Reply
for {
text, reply = proto.Parse(text)
if len(text) == 0 {
break
}
}
ProcessCommand and ProcessData
ProcessCommand should be used for an already parsed command (i.e., a complete
SMTP "line" excluding the line ending).
ProcessData should be used if the protocol is in DATA state.
reply = proto.ProcessCommand("EHLO localhost")
reply = proto.ProcessCommand("MAIL FROM:<test>")
reply = proto.ProcessCommand("DATA")
reply = proto.ProcessData("Test\r\n.\r\n")
Hooks
The state machine provides hooks to manipulate its behaviour.
See for more information.
| Hook | Description |
|---|---|
| LogHandler | Called for every log message |
| MessageReceivedHandler | Called for each message received |
| ValidateSenderHandler | Called after MAIL FROM |
| ValidateRecipientHandler | Called after RCPT TO |
| ValidateAuthenticationHandler | Called after AUTH |
| SMTPVerbFilter | Called for every SMTP command processed |
| TLSHandler | Callback mashup called after STARTTLS |
| GetAuthenticationMechanismsHandler | Called for each EHLO command |
Behaviour flags
The state machine also exports variables to control its behaviour:
See for more information.
| Variable | Description |
|---|---|
| RejectBrokenRCPTSyntax | Reject non-conforming RCPT syntax |
| RejectBrokenMAILSyntax | Reject non-conforming MAIL syntax |
| RequireTLS | Require STARTTLS before other commands |
| MaximumRecipients | Maximum recipients per message |
| MaximumLineLength | Maximum length of SMTP line |
Licence
Copyright © 2014-2015, Ian Kent (http://iankent.uk)
Released under MIT license, see LICENSE for details.