libcURL IMAP UID FETCH

Targets
1

I’m trying to retrieve some data from email server via imap protocol(with RB-libcURL). Unfortunately when I run the command UID FETCH NUMID (FLAGS INTERNALDATE RFC822.SIZE BODY.PEEK[HEADER.FIELDS (Message-Id DATE FROM SUBJECT TO SENDER REPLY-TO CC BCC)])
returns
* 1 FETCH (UID 3780 FLAGS (\Answered \Seen) INTERNALDATE "20-Oct-2020 19:50:23 +0200" RFC822.SIZE 158788 BODY[HEADER.FIELDS (MESSAGE-ID DATE FROM SUBJECT TO SENDER REPLY-TO CC BCC)] {220}

but not the content of the email. If I run the same command from terminal I get the same result but if I use the -v option everything works correctly. If instead I use for example the command fetch 1:* (UID FLAGS) everything works correctly.What am I missing?

curl -v imaps://imap.url.com/INBOX --user "user:pass" -X "UID FETCH 3780  (FLAGS INTERNALDATE RFC822.SIZE BODY.PEEK[HEADER.FIELDS (Message-Id DATE FROM SUBJECT TO SENDER REPLY-TO CC BCC)])"



Var curl As New libcURL.EasyHandle

Call curl.SetOption(libcURL.Opts.SSL_ENABLE_ALPN, False)
Call curl.SetOption(libcURL.Opts.SSL_VERIFYPEER, 0)
Call curl.SetOption(libcURL.Opts.SSL_VERIFYHOST, 0)


Call curl.SetOption(libcURL.Opts.URL, "imaps://imap.url.com/"+cartella)
Call curl.SetOption(libcURL.Opts.USERNAME, "user")
Call curl.SetOption(libcURL.Opts.PASSWORD, "pass")

if _comando <> "" then
  Call curl.SetOption(libcURL.Opts.CUSTOMREQUEST, _Comando)
end if 

Var mb As New MemoryBlock(0)
var bs as new BinaryStream(mb)
curl.DownloadStream = bs
if curl.Perform then

  bs.Close
  curl.DownloadStream = Nil

  Return mb

else
  MsgBox libcURL.FormatError(curl.LastError)
end if
2

I don’t know anything about IMAP but I suspect that the response you’re looking for is being delivered as headers rather than as content to be downloaded. This would explain why curl -v works: -v, for verbose, prints the response headers.

Try this:

' use cURLClient instead of EasyHandle unless you have a reason not to.
Var curl As New cURLClient 

Call curl.SetOption(libcURL.Opts.SSL_ENABLE_ALPN, False)
Call curl.SetOption(libcURL.Opts.SSL_VERIFYPEER, 0)  ' ?! unsafe
Call curl.SetOption(libcURL.Opts.SSL_VERIFYHOST, 0)  ' ?! unsafe

curl.Username = "user"
curl.Password = "pass"

if _comando <> "" then
  Call curl.SetRequestMethod(_Comando)
end if 

' Head() does a headers-only operation. This may or may not 
' actually be correct (idk about IMAP)
if curl.Head("imaps://imap.url.com/"+cartella) then
  
  Return curl.GetResponseHeaders() ' return an InternetHeaders object
  
else
  MsgBox libcURL.FormatError(curl.LastError)
end if
3

Thank you so much for the help! You’re right, the data is in the header however I’m not sure if this is correct behavior.