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Nilhcem / FakeSMTP

Dummy SMTP server with GUI for testing emails in applications easily.
http://nilhcem.github.com/FakeSMTP/
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Crash in FakeSMTP server when using C# SmtpClient with Authentication #7

Open dingetje opened 10 years ago

dingetje commented 10 years ago

When I try an authenticated session to FakeSMTP server using a C# SmtpClient, the server crashes:

17 Dec 2013 12:09:42 INFO org.subethamail.smtp.server.SMTPServer - SMTP server :25 starting 17 Dec 2013 12:09:42 INFO org.subethamail.smtp.server.ServerThread - SMTP server :25 started 17 Dec 2013 12:10:01 DEBUG org.subethamail.smtp.server.Session - SMTP connection from localhost/127.0.0.1, new connection count: 1 17 Dec 2013 12:10:01 DEBUG org.subethamail.smtp.server.Session - Server: 220 build-cct.sal-eng.nl ESMTP SubEthaSMTP null 17 Dec 2013 12:10:01 DEBUG org.subethamail.smtp.server.Session - Client: EHLO build-cct 17 Dec 2013 12:10:01 DEBUG org.subethamail.smtp.server.Session - Server: 250-build-cct.sal-eng.nl 250-8BITMIME 250-AUTH LOGIN 250 Ok 17 Dec 2013 12:10:01 DEBUG org.subethamail.smtp.server.Session - Client: AUTH login aWtrZQ== 17 Dec 2013 12:10:01 DEBUG org.subethamail.smtp.server.Session - Server: 334 VXNlcm5hbWU6 17 Dec 2013 12:10:01 DEBUG org.subethamail.smtp.server.Session - Server: 334 UGFzc3dvcmQ6 17 Dec 2013 12:10:01 ERROR org.subethamail.smtp.server.Session - Unexpected error in the SMTP handler thread java.lang.NullPointerException: null at org.subethamail.smtp.command.AuthCommand.execute(AuthCommand.java:88) ~[fakeSMTP-1.5.jar:na] at org.subethamail.smtp.server.RequireTLSCommandWrapper.execute(RequireTLSCommandWrapper.java:27) ~[fakeSMTP-1.5.jar:na] at org.subethamail.smtp.server.CommandHandler.handleCommand(CommandHandler.java:98) ~[fakeSMTP-1.5.jar:na] at org.subethamail.smtp.server.Session.runCommandLoop(Session.java:222) ~[fakeSMTP-1.5.jar:na] at org.subethamail.smtp.server.Session.run(Session.java:125) ~[fakeSMTP-1.5.jar:na] 17 Dec 2013 12:10:01 DEBUG org.subethamail.smtp.server.Session - Server: 421 4.3.0 Mail system failure, closing transmission channel

17 Dec 2013 12:10:01 ERROR com.nilhcem.fakesmtp.core.exception.UncaughtExceptionHandler - java.lang.NullPointerException: null at org.subethamail.smtp.command.AuthCommand.execute(AuthCommand.java:88) ~[fakeSMTP-1.5.jar:na] at org.subethamail.smtp.server.RequireTLSCommandWrapper.execute(RequireTLSCommandWrapper.java:27) ~[fakeSMTP-1.5.jar:na] at org.subethamail.smtp.server.CommandHandler.handleCommand(CommandHandler.java:98) ~[fakeSMTP-1.5.jar:na] at org.subethamail.smtp.server.Session.runCommandLoop(Session.java:222) ~[fakeSMTP-1.5.jar:na] at org.subethamail.smtp.server.Session.run(Session.java:125) ~[fakeSMTP-1.5.jar:na]

dingetje commented 10 years ago

Maybe this is because the C# SmtpClient uses the following authentication:

However, there exists a different, RFC compliant version of this behavior, where the client initially sends the userid already with the AUTH LOGIN method:

C: AUTH LOGIN ZHVtbXk= S: 334 UGFzc3dvcmQ6 C: Z2VoZWlt

Nilhcem commented 10 years ago

Hi,

Good catch, the server always returns "334 VXNlcm5hbWU6" (Username:), while, in this case, it should directly return "334 UGFzc3dvcmQ6" (Password:), as user already sent his userid with the AUTH LOGIN - Issue should be located in the com.nilhcem.fakesmtp.server.SMTPAuthHandler.auth() method and it may be easy to solve.

However I have difficulties to reproduce the crash, do you have a way (binary of the C# client that makes it crash / telnet commands to input) to reproduce easily?

Thanks,