Readme examples don't work

[dcohen21]

I'm looking into using fs2-mail for a new feature at my organization. I'm trying to familiarize myself with the API, but the examples in the Readme don't seem to work. Has the API changed considerably since the Readme was updated?

Specifically looking at the Receiving emails section, I'm having trouble with:

• clientTLS (I created a new SSLEngine to bypass this issue)
• imap.client - client doesn't look to be a part of this package - am I missing something here?

I haven't looked into the Sending emails section deeply, but I did notice that at the very least the M in EMailHeader is capitalized, whereas it should be EmailHeader.

[AdamChlupacek]

@dcohen21 Hey, sorry for such a late reply. I will go through the Readme and fix all the examples. We are still in kind of development with the library. I will try to get the Readme into some usable state.

[vatel]

me too, I can not resolve the problem with imap.client. Could you please help?

[vatel]

I was able to compile the code (see attached file) with some modifications, but it just establishes a TCP connection to gmail: SYN -> SYN+ACK -> ACK and nothing more, event no TLS connection. It does not send any data.
ImapTest.txt

How to run it correctly?

P.S. I am not familiar with fs2 nor streams, so I may be completely wrong... This is just an attempt

[AdamChlupacek]

@vatel sorry for late response, you can try to hit me on gitter next time, I am there all the time a and usually have time to reply atleast the basic stuff.

Could you try to write an empty chunk into the TLS socket? I think you are hitting one really dumb error in fs2-crypto, which I have not yet gotten around to fix :/

[vatel]

@AdamChlupacek thank you for response! I will try to do more experiments with TLS. Unfortunately for the moment I am not familiar with fs-* libraries at all (nor streaming concepts), so this is a bit difficult. Any working example of IMAP would be really appreciated!

[AdamChlupacek]

@vatel do ask in the fs2 gitter about anything fs2 related, there is great community of people who will reply to basically an fs2 and FP problem you have.

[AdamChlupacek]

@dcohen21 @vatel Just quick clarify to the API until I have time to properly give some love to the readMe.

the SSLEngine is not created since it kinda depends on your environment and where you will be connecting to. But in general if you want to jsut test it is ok to create one with default trust store, using:

import javax.net.ssl.SSLContext

val ctx = SSLContext.getInstance("TLS")
ctx.init(null, null, null)

val engine = ctx.createSSLEngine()
engine.setUseClientMode(true)

As for the imap.client that seems to be an oversight in the API, it is meant to exist but seems we forgot to do so. you can use IMAPClient.mk instead of it.

If you are using either IMAP or SMTP over TLS please do write an empty chunk first into the socket. As I said before, there are cases with TLS engine where you will not get any data unless you do so. This can be done via:

io.tcp.client[Task](new InetSocketAddress("hostName", 993)).flatMap { tcpSocket =>
Stream.eval(TLSEngine[Task](clientTLS)).flatMap { tlsEngine =>
Stream.eval(TLSSocket[Task](tcpSocket, tlsEngine)).flatMap { tlsSocket =>
Stream.eval(tlsSocket.write(Chunk.empty, None)).flatMap { _ =>
  ??? // <- create the desired imap/smtp client
}}}}

[vatel]

@AdamChlupacek thank you for sharing the code sending empty chunk! It has fixed the problem. So the example seems working now (the complete code is attached).
ImapTest.txt

[vatel]

Unfortunately, now I am stuck trying to read mail content. I have added the following block (which tries to read the 1st message in INBOX):

...
imapClient.select(tag[MailboxName]("INBOX")).flatMap { inboxStatus =>
                    println(s"inboxStatus = $inboxStatus")
                    imapClient.bodyStructureOf(tag[imap.MailUID](inboxStatus.getOrElse(null).uidNext)).map { bodyParts =>
                      println(s"bodyParts = $bodyParts")
                    }
...

but it gives error:

Exception in thread "main" java.lang.Throwable: Could not find start of body structure.
	at spinoco.fs2.mail.imap.IMAPClient$impl$.parseBodyStructure(IMAPClient.scala:381)
	at spinoco.fs2.mail.imap.IMAPClient$$anon$1.$anonfun$bodyStructureOf$1(IMAPClient.scala:205)
...

[AdamChlupacek]

Just a few things, do not use null no fs2-* libraries are ready for that, and they will most likely fail horribly if they encounter it.

The exception you are seeing is since the email you are trying to get does not exists. the uidNext gives the id of the next email that will appear at some time in the future. it is not yet an existing email.

[vatel]

@AdamChlupacek, yes of course, 'null' was just a quick stub.
Seems I do not understand how to list all (or unread only) messages in INBOX and then read message content by its ID - could you please point to correct call sequence? I was trying to call imapClient.emailHeaders(0L to Long.MaxValue) but it gives error (seems no such IDs).

[vatel]

@AdamChlupacek, I have found the answer:
imapClient.search(IMAPSearchTerm.ALL) returns all MailUIDs (also I see there IMAPSearchTerm.UNSEEN), after that I call imapClient.bodyStructureOf(MailUID)
Sorry for my previous post ;-)

[vatel]

@AdamChlupacek, is it possible to get the whole message content (including all headers and body parts) without parsing it and splitting to body parts? I see how to get text or bytes per specified body part, but seems I can not get content 'as is' (as byte array for example). For our purposes we need to take the whole message and pass it to further processing.

[AdamChlupacek]

@vatel Glad you found solution to your problem. Currently it is split headers and body parts separately. as for getting the whole body strictly into byte array etc, its just about running the Stream[F, Byte] and forcing it in to an array. There was actually discussion about this exact thing on gitter in fs2 channel (https://gitter.im/functional-streams-for-scala/fs2?at=5ae22737aeadbe0cc5297441).

[vatel]

@AdamChlupacek, thanks, I will dive into that discussion and try to understand. Streaming stuff is still too much complicated for me for the moment :-)