Includes build infrastructure & config updates required for changes in 8.16.1 MFC after: 5 days
152 lines
4.7 KiB
HTML
152 lines
4.7 KiB
HTML
<HTML>
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<HEAD><TITLE>smfi_insheader</TITLE></HEAD>
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<BODY>
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<!--
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$Id: smfi_insheader.html,v 1.11 2013-11-22 20:51:39 ca Exp $
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-->
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<H1>smfi_insheader</H1>
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<TABLE border="0" cellspacing=4 cellpadding=4>
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<!---------- Synopsis ----------->
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<TR><TH valign="top" align=left width=100>SYNOPSIS</TH><TD>
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<PRE>
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#include <libmilter/mfapi.h>
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int smfi_insheader(
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SMFICTX *ctx,
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int hdridx,
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char *headerf,
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char *headerv
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);
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</PRE>
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Prepend a header to the current message.
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</TD></TR>
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<!----------- Description ---------->
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<TR><TH valign="top" align=left>DESCRIPTION</TH><TD>
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<TABLE border="1" cellspacing=1 cellpadding=4>
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<TR align="left" valign=top>
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<TH width="80">Called When</TH>
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<TD>Called only from <A href="xxfi_eom.html">xxfi_eom</A>.</TD>
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</TR>
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<TR align="left" valign=top>
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<TH width="80">Effects</TH>
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<TD>Prepends a header to the current message.</TD>
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</TR>
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</TABLE>
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</TD></TR>
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<!----------- Arguments ---------->
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<TR><TH valign="top" align=left>ARGUMENTS</TH><TD>
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<TABLE border="1" cellspacing=0>
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<TR bgcolor="#dddddd"><TH>Argument</TH><TH>Description</TH></TR>
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<TR valign="top"><TD>ctx</TD>
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<TD>Opaque context structure.
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</TD></TR>
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<TR valign="top"><TD>hdridx</TD>
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<TD>The location in the internal header list where this header should
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be inserted; 0 makes it the topmost header, etc.
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</TD></TR>
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<TR valign="top"><TD>headerf</TD>
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<TD>The header name, a non-NULL, null-terminated string.
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</TD></TR>
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<TR valign="top"><TD>headerv</TD>
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<TD>The header value to be added, a non-NULL, null-terminated string. This may be the empty string.
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</TD></TR>
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</TABLE>
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</TD></TR>
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<!----------- Return values ---------->
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<TR>
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<TH valign="top" align=left>RETURN VALUES</TH>
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<TD>smfi_insheader returns MI_FAILURE if:
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<UL><LI>headerf or headerv is NULL.
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<LI>Adding headers in the current connection state is invalid.
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<LI>Memory allocation fails.
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<LI>A network error occurs.
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<LI><A HREF="smfi_register.html#SMFIF_ADDHDRS">SMFIF_ADDHDRS</A> is not set.
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</UL>
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Otherwise, it returns MI_SUCCESS.
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</TD>
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</TR>
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<!----------- Notes ---------->
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<TR align="left" valign=top>
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<TH>NOTES</TH>
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<TD>
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<UL>
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<LI>smfi_insheader does not change a message's existing headers.
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To change a header's current value, use
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<A HREF="smfi_chgheader.html">smfi_chgheader</A>.
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<LI>A filter which calls smfi_insheader must have set the
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<A HREF="smfi_register.html#SMFIF_ADDHDRS">SMFIF_ADDHDRS</A>
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flag.
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<LI>For smfi_insheader, filter order is important.
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<B>Later filters will see the header changes made by earlier ones.</B>
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<LI>A filter will receive <EM>only</EM> headers that have been sent
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by the SMTP client and those header modifications by earlier filters.
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It will <EM>not</EM> receive the headers that are inserted by sendmail
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itself.
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This makes the header insertion position highly dependent on
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the headers that exist in the incoming message
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and those that are configured to be added by sendmail.
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For example, sendmail will always add a
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<CODE>Received:</CODE> header to the beginning of the headers.
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Setting <CODE>hdridx</CODE> to 0 will actually insert the header
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before this <CODE>Received:</CODE> header.
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However, later filters can be easily confused as they receive
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the added header, but not the <CODE>Received:</CODE> header,
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thus making it hard to insert a header at a fixed position.
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<LI>If hdridx is a number larger than the number of headers in the message,
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the header will simply be appended.
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<LI>Neither the name nor the value of the header is checked for
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standards compliance.
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However, each line of the header must be under 2048 characters
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and should be under 998 characters.
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If longer headers are needed, make them multi-line.
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To make a multi-line header,
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insert a line feed (ASCII 0x0a, or <TT>\n</TT> in C)
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followed by at least one whitespace character
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such as a space (ASCII 0x20) or tab (ASCII 0x09, or <TT>\t</TT> in C).
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The line feed should NOT be preceded by a carriage return (ASCII 0x0d);
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the MTA will add this automatically.
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<B>It is the filter writer's responsibility to ensure that no standards
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are violated.</B>
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<LI>The MTA adds a leading space to an inserted header value unless
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the flag
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<A HREF="xxfi_negotiate.html#SMFIP_HDR_LEADSPC"><CODE>SMFIP_HDR_LEADSPC</CODE></A>
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is set, in which case the milter
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must include any desired leading spaces itself.
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</UL>
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</TD>
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</TR>
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<!----------- Example code ---------->
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<TR>
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<TH valign="top" align=left>EXAMPLE</TH>
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<TD>
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<PRE>
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int ret;
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SMFICTX *ctx;
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...
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ret = smfi_insheader(ctx, 0, "First", "See me?");
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</PRE>
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</TD>
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</TR>
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</TABLE>
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<HR size="1">
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<FONT size="-1">
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Copyright (c) 2004, 2006, 2009 Proofpoint, Inc. and its suppliers.
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All rights reserved.
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<BR>
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By using this file, you agree to the terms and conditions set
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forth in the LICENSE.
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</FONT>
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</BODY>
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</HTML>
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