Syntax error in MAIL FROM parameters

[Dauser Martin Johannes]

On Sun, 2018-02-18 at 02:51 +0100, Dauser Martin Johannes wrote:
> On Sat, 2018-02-17 at 23:31 +0100, Dauser Martin Johannes wrote:
> > On Sat, 2018-02-17 at 16:38 +0100, Christian Boltz wrote:
> > > Hello,
> > > 
> > > does someone know what Amavis wants to tell me with this message,
> > > and
> > > how to avoid these rejects?
> > > (the mail address is anonymized starting at "user=")
> > > 
> > > Feb 15 12:38:28 server amavis[3273]: (03273-17) ESMTP: 501 5.5.4
> > > Syntax error in MAIL FROM parameters; smtp_resp: MAIL
> > > FROM:<bounce+28
> > > f75a.232d6-user=example.com at mail.example2.com> BODY=8BITMIME
> > > SMTPUTF8\r\n
> > > 
> > 
> > 
> > > Looking at the amavis source code in /usr/sbin/amavisd shows
> > > (starting at line 20555)
> > > 
> > >         my($addr,$opt) = ($1,$2);  my($size,$dsn_ret,$dsn_envid);
> > >         my $msg ; my $msg_nopenalize = 0;
> > >         for (split(' ',$opt)) {
> > >           if (!/^ ( [A-Za-z0-9] [A-Za-z0-9-]*  ) =
> > >                   ( [\041-\074\076-\176]+ ) \z/xs) { # printable,
> > > not
> > > '=' or SP
> > >             $msg = "501 5.5.4 Syntax error in MAIL FROM
> > > parameters";
> > >           } else {
> > > 
> > > as likely source of the problem - at least, that's the only place
> > > where
> > > I found the error message.
> > > 
> > > Does someone know how I can avoid those rejects?
> > > 
> > > 
> > > Regards,
> > > 
> > > Christian Boltz
> > 
> > As this seems to be the only occurrence, it's most likely the
> > relevant
> > code.
> > 
> > I tried to phrase the main part of this if-clause's condition in a
> > sentence. I included the round brackets of the code.
> > 
> > If (not starting ( with an alphanumeric sign, followed by none or
> > any
> > amount of alphanumeric signs, including '-'), followed by '=' ,(
> > followed by at least one alphanumeric sign, including sings like
> > '!',
> > '[', '.' and so on, except for '=' and empty space) \z/xs)
> > 
> > then message $msg becomes "501 5.5.4 Syntax error in MAIL FROM
> > parameters"
> > 
> > Your
> > <bounce+28f75a.232d6-user=example.com at mail.example2.com>
> > 
> > includes a '<', a '+' and a '.' before '=' which isn't allowed by
> > this
> > if-clause. But beforehand the code splits some $opt in substrings
> > (separator is one empty space), so I'm not 100% sure what this if-
> > clause is looking at.
> > 
> 
> Just looked at the lines executed right before. The code evaluates
> some
> '<address> option1 option2 ...' and then this if-clause looks at
> those
> options!
> 
> BODY=8BITMIME SMTPUTF8\r\n
> 
> SMTPUTF8\r\n seems to be the trigger -- not sure if '\r\n' is part of
> the option or added by the error message. In fact SMTPUTF8 is a
> defined
> option I already read about.
> 
> But the culprit is the (old?) perl code:
>  
> My if-clause looks a bit different (EPEL Repository for RHEL7)
> 
>  my($addr,$opt) = ($1,$2);
>  my($size,$dsn_ret,$dsn_envid,$smtputf8);
>  my $msg; my $msg_nopenalize = 0;
>  for (split(' ',$opt)) {
>    if (!/^ ( [A-Za-z0-9] [A-Za-z0-9-]* )
>            (?: = ( [^=\000-\040\177]+ ) )? \z/xs) {
>            # any CHAR excluding "=", SP, and control characters
>      $msg = "501 5.5.4 Syntax error in MAIL FROM parameters";
>    } else 
> 
> Let's rephrase that:
> 
slightly wrong:
> if (not starting ( with an alphanumeric sign, followed by none or any
> amount of alphanumeric signs, including '-'), (followed once or never
> by '=' , which is then (followed by none or any amount of signs NOT
> being '=' , an oktalASCII 000 to 040 or oktalASCII 176)) \z/xs)
> 

Man it's time to go to bed!

if (not starting ( with an alphanumeric sign, followed by none or any
amount of alphanumeric signs, including '-'), (followed once or never
by '=' , which is then (followed by ONE or any amount of signs NOT
being '=' , an oktalASCII 000 to 040 or oktalASCII 176)) \z/xs)

* .... none or any amount
+ .... ONE or any amount

Sorry!

> So now, an option might be entirely without '=' but needs then to be
> made of alphanumeric signs and might include '-'. This '\r\n' won't
> do.
> 
> If the option includes  '=' the right part may contain any ASCII char
> excluding "=", space and (non-printable) control characters.
> 
> 
> > I hope this helps a bit.
> > Martin Johannes Dauser