libmilter/docs/xxfi_negotiate.html

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<HEAD><TITLE>xxfi_negotiate</TITLE></HEAD>
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$Id: xxfi_negotiate.html,v 1.24 2013-11-22 20:51:39 ca Exp $
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<H1>xxfi_negotiate</H1>

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<!---------- Synopsis ----------->
<TR><TH valign="top" align=left width=100>SYNOPSIS</TH><TD>
<PRE>
#include &lt;libmilter/mfapi.h&gt;
#include &lt;libmilter/mfdef.h&gt;
sfsistat (*xxfi_negotiate)(
        SMFICTX    *ctx,
	unsigned long f0,
	unsigned long f1,
	unsigned long f2,
	unsigned long f3,
	unsigned long *pf0,
	unsigned long *pf1,
	unsigned long *pf2,
	unsigned long *pf3);
</PRE>
</TD></TR>
<!----------- Description ---------->
<TR><TH valign="top" align=left>DESCRIPTION</TH><TD>
<TABLE border="1" cellspacing=1 cellpadding=4>
<TR>
<TH valign="top" align=left width=80>Called When</TH>
<TD>Once, at the start of each SMTP connection.</TD>
</TR>
<TR>
<TH valign="top" align=left width=80>Default Behavior</TH>
<TD>Return SMFIS_ALL_OPTS to change nothing.</TD>
</TR>
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<!----------- Arguments ---------->
<TR><TH valign="top" align=left>ARGUMENTS</TH><TD>
    <TABLE border="1" cellspacing=0>
    <TR bgcolor="#dddddd"><TH>Argument</TH><TH>Description</TH></TR>
    <TR><TD>ctx</TD>
	<TD>the opaque context structure.
	</TD></TR>
    <TR><TD>f0</TD>
	<TD>the actions offered by the MTA.
	</TD></TR>
    <TR><TD>f1</TD>
	<TD>the protocol steps offered by the MTA.
    <TR><TD>f2</TD>
	<TD>for future extensions.
	</TD></TR>
    <TR><TD>f3</TD>
	<TD>for future extensions.
	</TD></TR>
    <TR><TD>pf0</TD>
	<TD>the actions requested by the milter.
	</TD></TR>
    <TR><TD>pf1</TD>
	<TD>the protocol steps requested by the milter.
    <TR><TD>pf2</TD>
	<TD>for future extensions.
	</TD></TR>
    <TR><TD>pf3</TD>
	<TD>for future extensions.
	</TD></TR>
    </TABLE>
</TD></TR>

<!----------- Return values ---------->
<TR>
<TH valign="top" align=left>SPECIAL RETURN VALUES</TH>
<TD><TABLE border="1" cellspacing=0>
  <TR bgcolor="#dddddd"><TH>Return value</TH><TH>Description</TH></TR>
  <TR valign="top">
     <TD>SMFIS_ALL_OPTS</TD>
     <TD>
If a milter just wants to inspect the available protocol steps
and actions, then it can return
SMFIS_ALL_OPTS
and the MTA will make all protocol steps and actions available
to the milter.
In this case, no values should be assigned to the output parameters
<CODE>pf0</CODE> - <CODE>pf3</CODE>
as they will be ignored.
     </TD>
  </TR>
  <TR valign="top">
     <TD>SMFIS_REJECT</TD>
     <TD>Milter startup fails and it will not be contacted again
(for the current connection).
     </TD>
  </TR>
  <TR valign="top">
     <TD>SMFIS_CONTINUE</TD>
     <TD>Continue processing.
	In this case the milter <EM>must</EM> set all output parameters
	<CODE>pf0</CODE> - <CODE>pf3</CODE>.
	See below for an explanation how to set those output parameters.
     </TD>
  </TR>
</TABLE>
</TR>

<!----------- Notes ---------->
<TR>
<TH valign="top" align=left>NOTES</TH>
<TD>This function allows a milter to dynamically determine and
request operations and actions during startup.
In previous versions, the actions (f0) were fixed in the
<A HREF="smfi_register.html#flags">flags</A> field of the
<A HREF="smfi_register.html#smfiDesc">smfiDesc</A>
structure
and the protocol steps (f1) were implicitly derived by checking whether
a callback was defined.
Due to the extensions in the new milter version,
such a static selection will not work if a milter requires
new actions that are not available when talking to an older MTA.
Hence in the negotiation callback a milter can determine
which operations are available and dynamically select
those which it needs and which are offered.
If some operations are not available, the milter may either fall back
to an older mode or abort the session and ask the user to upgrade.

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<P>
The protocol steps are defined in
<CODE>include/libmilter/mfdef.h</CODE>:
the macros start with
<CODE>SMFIP_</CODE>.
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<P>
Protocol steps
(<CODE>f1</CODE>, <CODE>*pf1</CODE>):
<UL>
<LI><A NAME="SMFIP_RCPT_REJ"><CODE>SMFIP_RCPT_REJ</CODE></A>:
By setting this bit, a milter can request that the
MTA should also send <CODE>RCPT</CODE> commands that have been rejected
because the user is unknown (or similar reasons), but not those
which have been rejected because of syntax errors etc.
If a milter requests this protocol step,
then it should check the macro
<CODE>{rcpt_mailer}</CODE>:
if that is set to
<CODE>error</CODE>,
then the recipient will be rejected by the MTA.
Usually the macros
<CODE>{rcpt_host}</CODE> and <CODE>{rcpt_addr}</CODE>
will contain an enhanced status code and an error text
in that case, respectively.

<LI><A NAME="SMFIP_SKIP"><CODE>SMFIP_SKIP</CODE></A>
indicates that the MTA understand the
<A HREF="api.html#SMFIS_SKIP">SMFIS_SKIP</A>
return code.

<LI><A NAME="SMFIP_NR_"><CODE>SMFIP_NR_*</CODE></A>
indicates that the MTA understand the
<A HREF="api.html#SMFIS_NOREPLY">SMFIS_NOREPLY</A>
return code.
There are flags for various protocol stages:

<UL>

<LI><A NAME="SMFIP_NR_CONN"><CODE>SMFIP_NR_CONN</CODE></A>:
<A HREF="xxfi_connect.html">xxfi_connect()</A>

<LI><A NAME="SMFIP_NR_HELO"><CODE>SMFIP_NR_HELO</CODE></A>:
<A HREF="xxfi_helo.html">xxfi_helo()</A>

<LI><A NAME="SMFIP_NR_MAIL"><CODE>SMFIP_NR_MAIL</CODE></A>:
<A HREF="xxfi_envfrom.html">xxfi_envfrom()</A>

<LI><A NAME="SMFIP_NR_RCPT"><CODE>SMFIP_NR_RCPT</CODE></A>:
<A HREF="xxfi_envrcpt.html">xxfi_envrcpt()</A>

<LI><A NAME="SMFIP_NR_DATA"><CODE>SMFIP_NR_DATA</CODE></A>:
<A HREF="xxfi_data.html">xxfi_data()</A>

<LI><A NAME="SMFIP_NR_UNKN"><CODE>SMFIP_NR_UNKN</CODE></A>:
<A HREF="xxfi_unknown.html">xxfi_unknown()</A>

<LI><A NAME="SMFIP_NR_EOH"><CODE>SMFIP_NR_EOH</CODE></A>:
<A HREF="xxfi_eoh.html">xxfi_eoh()</A>

<LI><A NAME="SMFIP_NR_BODY"><CODE>SMFIP_NR_BODY</CODE></A>:
<A HREF="xxfi_body.html">xxfi_body()</A>

<LI><A NAME="SMFIP_NR_HDR"><CODE>SMFIP_NR_HDR</CODE></A>:
<A HREF="xxfi_header.html">xxfi_header()</A>

</UL>

<LI><A NAME="SMFIP_HDR_LEADSPC"><CODE>SMFIP_HDR_LEADSPC</CODE></A>
indicates that the MTA can send header values with leading space intact.
If this protocol step is requested, then the MTA will also not add a leading
space to headers when they are added, inserted, or changed.

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<LI>The MTA can be instructed not to send information about
various SMTP stages, these flags start with:
<A NAME="SMFIP_NO"><CODE>SMFIP_NO*</CODE></A>.
<UL>
<LI><A NAME="SMFIP_NOCONNECT"><CODE>SMFIP_NOCONNECT</CODE></A>:
<A HREF="xxfi_connect.html">xxfi_connect()</A>
<LI><A NAME="SMFIP_NOHELO"><CODE>SMFIP_NOHELO</CODE></A>:
<A HREF="xxfi_header.html">xxfi_header()</A>
<LI><A NAME="SMFIP_NOMAIL"><CODE>SMFIP_NOMAIL</CODE></A>:
<A HREF="xxfi_envfrom.html">xxfi_envfrom()</A>
<LI><A NAME="SMFIP_NORCPT"><CODE>SMFIP_NORCPT</CODE></A>:
<A HREF="xxfi_envrcpt.html">xxfi_envrcpt()</A>
<LI><A NAME="SMFIP_NOBODY"><CODE>SMFIP_NOBODY</CODE></A>:
<A HREF="xxfi_body.html">xxfi_body()</A>
<LI><A NAME="SMFIP_NOHDRS"><CODE>SMFIP_NOHDRS</CODE></A>:
<A HREF="xxfi_header.html">xxfi_header()</A>
<LI><A NAME="SMFIP_NOEOH"><CODE>SMFIP_NOEOH</CODE></A>:
<A HREF="xxfi_eoh.html">xxfi_eoh()</A>
<LI><A NAME="SMFIP_NOUNKNOWN"><CODE>SMFIP_NOUNKNOWN</CODE></A>:
<A HREF="xxfi_unknown.html">xxfi_unknown()</A>
<LI><A NAME="SMFIP_NODATA"><CODE>SMFIP_NODATA</CODE></A>:
<A HREF="xxfi_data.html">xxfi_data()</A>
</UL>

For each of these xxfi_* callbacks that a milter does not use
the corresponding flag <EM>should</EM> be set in
<CODE>*pf1</CODE>.

</UL>

<P>
The available actions
(<CODE>f0</CODE>, <CODE>*pf0</CODE>)
are
<!--
defined in
<CODE>include/libmilter/mfapi.h</CODE>:
the macros start with
<CODE>SMFIF_</CODE>;
these are
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described
<A HREF="smfi_register.html#flags">elsewhere (xxfi_flags)</A>.

<P>
If a milter returns SMFIS_CONTINUE, then it <EM>must</EM>
set the desired actions and protocol steps
via the (output) parameters
<CODE>pf0</CODE>
and
<CODE>pf1</CODE>
(which correspond to
<CODE>f0</CODE>
and
<CODE>f1</CODE>, respectively).
The (output) parameters
<CODE>pf2</CODE> and
<CODE>pf3</CODE>
should be set to 0 for compatibility with future versions.

</TD>
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Copyright (c) 2006 Proofpoint, Inc. and its suppliers.
All rights reserved.
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By using this file, you agree to the terms and conditions set
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