Bug #9627: SMTP does not properly dot-stuff an unterminated last line

• Status: Closed
• Assignee: -
• Target version: -
• ruby -v: ruby 1.9.3p448 (2013-06-27 revision 41675) [x86_64-linux]
• Backport: 1.9.3: REQUIRED, 2.0.0: DONE, 2.1: DONE

[yyyc514 (Josh Goebel)]

str = "Date: Wed, 12 Mar 2014 16:02:26 -0400\r\nFrom: [e-mail]\r\nTo: [e-mail]\r\nMessage-ID: <[e-mail]>\r\nMime-Version: 1.0\r\nContent-Type: text/plain;\r\n charset=UTF-8\r\nContent-Transfer-Encoding: 7bit\r\n\r\nlook, a period with no endline\r\n."

      smtp = Net::SMTP.new(...)
      smtp.start(...) do |smtp_obj|
        response = smtp_obj.sendmail(message, "[e-mail]","[e-mail]")
      end

The SMTP server is going to throw a 400 or 500 error (depending on it's configuration) because the last period is send un-stuffed in the DATA block:

look, a period with no endline
.
.

When it should be:

look, a period with no end line
..
.

(ie, not dot-stuffed) and the second period the SMTP server doesn't know what to do with. Adding an additional new-line fixes the problem, but I the in-line documentation for SMTP send_message does not say anything about a new-line being requires for message sending to work.

Sorry, I can't test against the latest Ruby right now, but this is confirmed against 1.9.3 r448. If someone can confirm against newer that would be great.

I did do a search for "SMTP" and did not see this reported anywhere in the Issues database.

I had originally filed a pull request against Mail: https://github.com/mikel/mail/pull/683

[yyyc514 (Josh Goebel)]

If I'm understanding this properly I think this monkey-patch is all it takes to fix it:

module Net
  class InternetMessageIO

    def using_each_crlf_line
      @wbuf = ''
      yield
      if not @wbuf.empty?   # unterminated last line
        write0 dot_stuff(@wbuf.chomp) + "\r\n"
      elsif @written_bytes == 0   # empty src
        write0 "\r\n"
      end
      write0 ".\r\n"
      @wbuf = nil
    end
  
    def dot_stuff(s)
      s.sub(/\A\./, '..')
    end
    
  end
end

You simply have to dot-stuff the remaining buffer if necessary...

[nobu (Nobuyoshi Nakada)]

• Status changed from Open to Closed
• % Done changed from 0 to 100

Applied in changeset r46060.

---

net/protocol.rb: fix SMTP dot stuffing

• net/protocol.rb (using_each_crlf_line): fix SMTP dot-stuffing
  for messages not ending with a new-line.
  [ruby-core:61441] [Bug #9627] [fix GH-616]

[drbrain (Eric Hodel)]

• Backport changed from 1.9.3: UNKNOWN, 2.0.0: UNKNOWN, 2.1: UNKNOWN to 1.9.3: REQUIRED, 2.0.0: REQUIRED, 2.1: REQUIRED

[nagachika (Tomoyuki Chikanaga)]

• Backport changed from 1.9.3: REQUIRED, 2.0.0: REQUIRED, 2.1: REQUIRED to 1.9.3: REQUIRED, 2.0.0: REQUIRED, 2.1: DONE

Backported into ruby_2_1 branch at r46496.

[usa (Usaku NAKAMURA)]

• Backport changed from 1.9.3: REQUIRED, 2.0.0: REQUIRED, 2.1: DONE to 1.9.3: REQUIRED, 2.0.0: DONE, 2.1: DONE

backported into ruby_2_0_0 at r46515.