1<HTML> 2<HEAD><TITLE>smfi_insheader</TITLE></HEAD> 3<BODY> 4<!-- 5$Id: smfi_insheader.html,v 1.9 2006/12/21 18:30:35 ca Exp $ 6--> 7<H1>smfi_insheader</H1> 8 9<TABLE border="0" cellspacing=4 cellpadding=4> 10<!---------- Synopsis -----------> 11<TR><TH valign="top" align=left width=100>SYNOPSIS</TH><TD> 12<PRE> 13#include <libmilter/mfapi.h> 14int smfi_insheader( 15 SMFICTX *ctx, 16 int hdridx, 17 char *headerf, 18 char *headerv 19); 20</PRE> 21Prepend a header to the current message. 22</TD></TR> 23 24<!----------- Description ----------> 25<TR><TH valign="top" align=left>DESCRIPTION</TH><TD> 26<TABLE border="1" cellspacing=1 cellpadding=4> 27<TR align="left" valign=top> 28<TH width="80">Called When</TH> 29<TD>Called only from <A href="xxfi_eom.html">xxfi_eom</A>.</TD> 30</TR> 31<TR align="left" valign=top> 32<TH width="80">Effects</TH> 33<TD>Prepends a header to the current message.</TD> 34</TR> 35</TABLE> 36 37<!----------- Arguments ----------> 38<TR><TH valign="top" align=left>ARGUMENTS</TH><TD> 39 <TABLE border="1" cellspacing=0> 40 <TR bgcolor="#dddddd"><TH>Argument</TH><TH>Description</TH></TR> 41 <TR valign="top"><TD>ctx</TD> 42 <TD>Opaque context structure. 43 </TD></TR> 44 <TR valign="top"><TD>hdridx</TD> 45 <TD>The location in the internal header list where this header should 46 be inserted; 0 makes it the topmost header, etc. 47 </TD></TR> 48 <TR valign="top"><TD>headerf</TD> 49 <TD>The header name, a non-NULL, null-terminated string. 50 </TD></TR> 51 <TR valign="top"><TD>headerv</TD> 52 <TD>The header value to be added, a non-NULL, null-terminated string. This may be the empty string. 53 </TD></TR> 54 </TABLE> 55</TD></TR> 56 57<!----------- Return values ----------> 58<TR> 59<TH valign="top" align=left>RETURN VALUES</TH> 60 61<TD>smfi_insheader returns MI_FAILURE if: 62<UL><LI>headerf or headerv is NULL. 63 <LI>Adding headers in the current connection state is invalid. 64 <LI>Memory allocation fails. 65 <LI>A network error occurs. 66 <LI>SMFIF_ADDHDRS was not set when <A href="smfi_register.html">smfi_register</A> was called. 67</UL> 68Otherwise, it returns MI_SUCCESS. 69</TD> 70</TR> 71 72<!----------- Notes ----------> 73<TR align="left" valign=top> 74<TH>NOTES</TH> 75<TD> 76<UL> 77 <LI>smfi_insheader does not change a message's existing headers. 78 To change a header's current value, use 79 <A HREF="smfi_chgheader.html">smfi_chgheader</A>. 80 <LI>A filter which calls smfi_insheader must have set the SMFIF_ADDHDRS 81 flag in the smfiDesc_str passed to 82 <A href="smfi_register.html">smfi_register</A>. 83 <LI>For smfi_insheader, filter order is important. 84 <B>Later filters will see the header changes made by earlier ones.</B> 85 <LI>A filter will receive <EM>only</EM> headers that have been sent 86 by the SMTP client and those header modifications by earlier filters. 87 It will <EM>not</EM> receive the headers that are inserted by sendmail 88 itself. 89 This makes the header insertion position highly dependent on 90 the headers that exist in the incoming message 91 and those that are configured to be added by sendmail. 92 For example, sendmail will always add a 93 <CODE>Received:</CODE> header to the beginning of the headers. 94 Setting <CODE>hdridx</CODE> to 0 will actually insert the header 95 before this <CODE>Received:</CODE> header. 96 However, later filters can be easily confused as they receive 97 the added header, but not the <CODE>Received:</CODE> header, 98 thus making it hard to insert a header at a fixed position. 99 <LI>If hdridx is a number larger than the number of headers in the message, 100 the header will simply be appended. 101 <LI>Neither the name nor the value of the header is checked for 102 standards compliance. 103 However, each line of the header must be under 2048 characters 104 and should be under 998 characters. 105 If longer headers are needed, make them multi-line. 106 To make a multi-line header, 107 insert a line feed (ASCII 0x0a, or <TT>\n</TT> in C) 108 followed by at least one whitespace character 109 such as a space (ASCII 0x20) or tab (ASCII 0x09, or <TT>\t</TT> in C). 110 The line feed should NOT be preceded by a carriage return (ASCII 0x0d); 111 the MTA will add this automatically. 112 <B>It is the filter writer's responsibility to ensure that no standards 113 are violated.</B> 114</UL> 115</TD> 116</TR> 117 118<!----------- Example code ----------> 119<TR> 120<TH valign="top" align=left>EXAMPLE</TH> 121 122<TD> 123 <PRE> 124 int ret; 125 SMFICTX *ctx; 126 127 ... 128 129 ret = smfi_insheader(ctx, 0, "First", "See me?"); 130 </PRE> 131</TD> 132</TR> 133 134</TABLE> 135 136<HR size="1"> 137<FONT size="-1"> 138Copyright (c) 2004, 2006 Sendmail, Inc. and its suppliers. 139All rights reserved. 140<BR> 141By using this file, you agree to the terms and conditions set 142forth in the LICENSE. 143</FONT> 144</BODY> 145</HTML> 146