Hangs in SMTP Authenticate method using Amazon SES

[cdmackie]

using (var smtp = new SmtpClient())
{
    smtp.Connect("email-smtp.us-east-1.amazonaws.com", 587, MailKit.Security.SecureSocketOptions.StartTlsWhenAvailable);
    smtp.Authenticate("my-ses-creds, "ses-creds-password");
}

The call to Authenticate hangs.

I turned on the ProtocolLogger and this is what I get.

Connected to smtp://email-smtp.us-east-1.amazonaws.com:587/
S: 220 email-smtp.amazonaws.com ESMTP SimpleEmailService-1157831919 SPo1Eh0XEnJZdv07GKHV
C: EHLO [192.168.0.5]
S: 250-email-smtp.amazonaws.com
S: 250-8BITMIME
S: 250-SIZE 10485760
S: 250-STARTTLS
S: 250-AUTH PLAIN LOGIN
S: 250 Ok
C: STARTTLS
S: 220 Ready to start TLS
C: EHLO [192.168.0.5]
S: 250-email-smtp.amazonaws.com
S: 250-8BITMIME
S: 250-SIZE 10485760
S: 250-STARTTLS
S: 250-AUTH PLAIN LOGIN
S: 250 Ok
C: AUTH PLAIN [my-encoded-credentials]==
S: 4

(it really ends at the S: 4)

Win 8.1 / VS 2012
MailKit 1.2.10.0

edit:

The issue is in SmtpStream::ReadResponse. ReadAhead() only gives it one byte (a "4") and so it gets into an infinite loop. Debugging it through doesn't always show the problem because it's timing related. Without spending too much time on what's going on, I changed ln 468 to if (memory.Length >= 0 || inputIndex == inputEnd) just so I could progress. The logic there can't seem to handle reading one byte at a time. Maybe ReadAhead should give it a whole line.

[jstedfast]

Thanks for the bug report and for narrowing it down!