2 <HEAD><TITLE>Milter API</TITLE></HEAD>
5 $Id: api.html,v 1.39 2013-11-22 20:51:39 ca Exp $
11 <LI><A HREF="#LibraryControlFunctions">Library Control Functions</A>
12 <LI><A HREF="#DataAccessFunctions">Data Access Functions</A>
13 <LI><A HREF="#MessageModificationFunctions">Message Modification Functions</A>
14 <LI><A HREF="#Callbacks">Callbacks</A>
15 <LI><A HREF="#Miscellaneous">Miscellaneous</A>
18 <H2><A NAME="LibraryControlFunctions">Library Control Functions</A></H2>
20 Before handing control to libmilter (by calling
21 <A HREF="smfi_main.html">smfi_main</A>), a filter may call the following
22 functions to set libmilter parameters.
23 In particular, the filter must call
24 <A HREF="smfi_register.html">smfi_register</A> to register its callbacks.
25 Each function will return either MI_SUCCESS or MI_FAILURE to
26 indicate the status of the operation.
29 None of these functions communicate with the MTA.
30 All alter the library's state, some of which
31 is communicated to the MTA inside
32 <A HREF="smfi_main.html">smfi_main</A>.
35 <TABLE BORDER="1" CELLSPACING=0 CELLPADDING=2><TR BGCOLOR="#dddddd"><TH>Function</TH><TH>Description</TH></TR>
37 <TR><TD><A HREF="smfi_opensocket.html">smfi_opensocket</A></TD><TD>Try to create the interface socket.</TD></TR>
39 <TR><TD><A HREF="smfi_register.html">smfi_register</A></TD><TD>Register a filter.</TD></TR>
41 <TR><TD><A HREF="smfi_setconn.html">smfi_setconn</A></TD><TD>Specify socket to use.</TD></TR>
43 <TR><TD><A HREF="smfi_settimeout.html">smfi_settimeout</A></TD><TD>Set timeout.</TD></TR>
45 <TR><TD><A HREF="smfi_setbacklog.html">smfi_setbacklog</A></TD><TD>Define the incoming <CODE>listen(2)</CODE> queue size.</TD></TR>
47 <TR><TD><A HREF="smfi_setdbg.html">smfi_setdbg</A></TD><TD>Set the milter library debugging (tracing) level.</TD></TR>
49 <TR><TD><A HREF="smfi_stop.html">smfi_stop</A></TD><TD>Cause an orderly shutdown.</TD></TR>
51 <TR><TD><A HREF="smfi_main.html">smfi_main</A></TD><TD>Hand control to libmilter.</TD></TR>
55 <H2><A NAME="DataAccessFunctions">Data Access Functions</A></H2>
57 The following functions may be called from within the filter-defined callbacks
58 to access information about the current connection or message.
60 <TABLE BORDER="1" CELLSPACING=0 CELLPADDING=2><TR bgcolor="#dddddd"><TH>Function</TH><TH>Description</TH></TR>
61 <TR><TD><A HREF="smfi_getsymval.html">smfi_getsymval</A></TD><TD>Return the value
62 of a symbol.</TD></TR>
64 <TR><TD><A HREF="smfi_getpriv.html">smfi_getpriv</A></TD><TD>Get the private data
67 <TR><TD><A HREF="smfi_setpriv.html">smfi_setpriv</A></TD><TD>Set the private data
70 <TR><TD><A HREF="smfi_setreply.html">smfi_setreply</A></TD><TD>Set the specific
71 reply code to be used.</TD></TR>
73 <TR><TD><A HREF="smfi_setmlreply.html">smfi_setmlreply</A></TD><TD>Set the
74 specific multi-line reply to be used.</TD></TR>
78 <H2><A NAME="MessageModificationFunctions">Message Modification Functions</A></H2>
80 The following functions change a message's contents and attributes.
81 <EM>They may only be called in <A HREF="xxfi_eom.html">xxfi_eom</A></EM>.
82 All of these functions may invoke additional communication with the MTA.
83 They will return either MI_SUCCESS or MI_FAILURE to indicate the status of
85 Message data (senders, recipients, headers, body chunks)
86 passed to these functions via parameters is copied and does not need to be
87 preserved (i.e., allocated memory can be freed).
90 A filter which might call a message modification function
91 must set the appropriate flag
92 (<A HREF="#SMFIF">listed below</A>),
94 in the description passed to <A HREF="smfi_register.html">smfi_register</A>
95 or via <A HREF="xxfi_negotiate.html">xxfi_negotiate</A>.
96 Failure to do so will cause the MTA to treat a call to the function
97 as a failure of the filter, terminating its connection.
100 Note that the status returned indicates only whether or not the
101 filter's message was successfully sent to the MTA, not whether or not
102 the MTA performed the requested operation.
104 <A HREF="smfi_addheader.html">smfi_addheader</A>, when called with an
105 illegal header name, will return MI_SUCCESS even though the MTA may
106 later refuse to add the illegal header.
108 <TABLE BORDER="1" CELLSPACING=0 CELLPADDING=2><TR BGCOLOR="#dddddd"><TH>Function</TH><TH>Description</TH><TH><A NAME="SMFIF">SMFIF_* flag</A></TH></TR>
109 <TR><TD><A HREF="smfi_addheader.html">smfi_addheader</A></TD><TD>Add a header to
110 the message.</TD><TD>SMFIF_ADDHDRS</TD></TR>
112 <TR><TD><A HREF="smfi_chgheader.html">smfi_chgheader</A></TD><TD>Change or delete a header.</TD><TD>SMFIF_CHGHDRS</TD></TR>
114 <TR><TD><A HREF="smfi_insheader.html">smfi_insheader</A></TD><TD>Insert a
115 header into the message.</TD><TD>SMFIF_ADDHDRS</TD></TR>
117 <TR><TD><A HREF="smfi_chgfrom.html">smfi_chgfrom</A></TD><TD>Change the
118 envelope sender address.</TD><TD>SMFIF_CHGFROM</TD></TR>
120 <TR><TD><A HREF="smfi_addrcpt.html">smfi_addrcpt</A></TD><TD>Add a recipient to
121 the envelope.</TD><TD>SMFIF_ADDRCPT</TD></TR>
123 <TR><TD><A HREF="smfi_addrcpt_par.html">smfi_addrcpt_par</A></TD><TD>Add
124 a recipient including ESMTP parameter to the envelope.
125 </TD><TD>SMFIF_ADDRCPT_PAR</TD></TR>
127 <TR><TD><A HREF="smfi_delrcpt.html">smfi_delrcpt</A></TD><TD>Delete a recipient
128 from the envelope.</TD><TD>SMFIF_DELRCPT</TD></TR>
130 <TR><TD><A HREF="smfi_replacebody.html">smfi_replacebody</A></TD><TD>Replace the
131 body of the message.</TD><TD>SMFIF_CHGBODY</TD></TR>
135 <H2>Other Message Handling Functions</H2>
137 The following functions provide special case handling instructions for
138 milter or the MTA, without altering the content or status of the message.
139 <EM>They too may only be called in <A HREF="xxfi_eom.html">xxfi_eom</A></EM>.
140 All of these functions may invoke additional communication with the MTA.
141 They will return either MI_SUCCESS or MI_FAILURE to indicate the status of
145 Note that the status returned indicates only whether or not the
146 filter's message was successfully sent to the MTA, not whether or not
147 the MTA performed the requested operation.
150 <TABLE BORDER="1" CELLSPACING=0 CELLPADDING=2><TR BGCOLOR="#dddddd"><TH>Function</TH><TH>Description</TH></TR>
151 <TR><TD><A HREF="smfi_progress.html">smfi_progress</A></TD><TD>Report operation in progress.</TD></TR>
153 <TR><TD><A HREF="smfi_quarantine.html">smfi_quarantine</A></TD><TD>Quarantine a message.</TD></TR>
157 <H2><A NAME="Callbacks">Callbacks</A></H2>
159 The filter should implement one or more of the following callbacks,
160 which are registered via <A HREF="smfi_register.html">smfi_register</A>:
163 <TABLE BORDER="1" CELLSPACING=0 CELLPADDING=2><TR BGCOLOR="#dddddd"><TH>Function</TH><TH>Description</TH></TR>
165 <TR><TD><A HREF="xxfi_connect.html">xxfi_connect</A></TD><TD>connection info</TD></TR>
167 <TR><TD><A HREF="xxfi_helo.html">xxfi_helo</A></TD><TD>SMTP HELO/EHLO command</TD></TR>
169 <TR><TD><A HREF="xxfi_envfrom.html">xxfi_envfrom</A></TD><TD>envelope sender</TD></TR>
171 <TR><TD><A HREF="xxfi_envrcpt.html">xxfi_envrcpt</A></TD><TD>envelope recipient</TD></TR>
173 <TR><TD><A HREF="xxfi_data.html">xxfi_data</A></TD><TD>DATA command</TD></TR>
175 <TR><TD><A HREF="xxfi_unknown.html">xxfi_unknown</A></TD><TD>Unknown SMTP command</TD></TR>
177 <TR><TD><A HREF="xxfi_header.html">xxfi_header</A></TD><TD>header</TD></TR>
179 <TR><TD><A HREF="xxfi_eoh.html">xxfi_eoh</A></TD><TD>end of header</TD></TR>
181 <TR><TD><A HREF="xxfi_body.html">xxfi_body</A></TD><TD>body block</TD></TR>
183 <TR><TD><A HREF="xxfi_eom.html">xxfi_eom</A></TD><TD>end of message</TD></TR>
185 <TR><TD><A HREF="xxfi_abort.html">xxfi_abort</A></TD><TD>message aborted</TD></TR>
187 <TR><TD><A HREF="xxfi_close.html">xxfi_close</A></TD><TD>connection cleanup</TD></TR>
189 <TR><TD><A HREF="xxfi_negotiate.html">xxfi_negotiate</A></TD><TD>option negotiation</TD></TR>
194 The above callbacks should all return one of the following return values,
195 having the indicated meanings.
196 Any return other than one of the below values constitutes an error,
197 and will cause sendmail to terminate its connection to the offending filter.
199 <P><A NAME="conn-spec">Milter</A> distinguishes between recipient-,
200 message-, and connection-oriented routines.
201 Recipient-oriented callbacks may affect the processing
202 of a single message recipient;
203 message-oriented callbacks, a single message;
204 connection-oriented callbacks, an entire connection
205 (during which multiple messages may be delivered
206 to multiple sets of recipients).
207 <A HREF="xxfi_envrcpt.html">xxfi_envrcpt</A> is recipient-oriented.
208 <A HREF="xxfi_negotiate.html">xxfi_negotiate</A>,
209 <A HREF="xxfi_connect.html">xxfi_connect</A>,
210 <A HREF="xxfi_helo.html">xxfi_helo</A> and
211 <A HREF="xxfi_close.html">xxfi_close</A> are connection-oriented.
212 All other callbacks are message-oriented.
215 <TABLE BORDER="1" CELLSPACING=0 CELLPADDING=2>
216 <TR BGCOLOR="#dddddd"><TH>Return value</TH><TH>Description</TH></TR>
218 <TD>SMFIS_CONTINUE</TD>
219 <TD>Continue processing the current connection, message, or recipient.
223 <TD>SMFIS_REJECT</TD>
224 <TD>For a connection-oriented routine, reject this connection; call <A HREF="xxfi_close.html">xxfi_close</A>.<BR>
225 For a message-oriented routine (except
226 <A HREF="xxfi_abort.html">xxfi_abort</A>), reject this message.<BR>
227 For a recipient-oriented routine, reject the current recipient (but continue processing the current message).
231 <TD>SMFIS_DISCARD</TD>
232 <TD>For a message- or recipient-oriented routine, accept this message, but silently discard it.<BR>
233 SMFIS_DISCARD should not be returned by a connection-oriented routine.
237 <TD>SMFIS_ACCEPT</TD>
238 <TD>For a connection-oriented routine, accept this connection without further filter processing; call <A HREF="xxfi_close.html">xxfi_close</A>.<BR>
239 For a message- or recipient-oriented routine, accept this message without further filtering.<BR>
243 <TD>SMFIS_TEMPFAIL</TD>
244 <TD>Return a temporary failure, i.e., the corresponding SMTP command will return an appropriate 4xx status code.
245 For a message-oriented routine (except <A HREF="xxfi_envfrom.html">xxfi_envfrom</A>), fail for this message.<BR>
246 For a connection-oriented routine, fail for this connection; call <A HREF="xxfi_close.html">xxfi_close</A>.<BR>
247 For a recipient-oriented routine, only fail for the current recipient; continue message processing.
252 <TD><A NAME="SMFIS_SKIP">SMFIS_SKIP</A></TD>
253 <TD>Skip further callbacks of the same type in this transaction.
254 Currently this return value is only allowed in
255 <A HREF="xxfi_body.html">xxfi_body()</A>.
256 It can be used if a milter has received sufficiently many
257 body chunks to make a decision, but still wants to invoke
258 message modification functions that are only allowed to be called from
259 <A HREF="xxfi_eom.html">xxfi_eom()</A>.
260 Note: the milter <EM>must</EM>
261 <A HREF="xxfi_negotiate.html">negotiate</A>
262 this behavior with the MTA, i.e., it must check whether
264 <A HREF="xxfi_negotiate.html#SMFIP_SKIP"><CODE>SMFIP_SKIP</CODE></A>
265 is available and if so, the milter must request it.
270 <TD><A NAME="SMFIS_NOREPLY">SMFIS_NOREPLY</A></TD>
271 <TD>Do not send a reply back to the MTA.
272 The milter <EM>must</EM>
273 <A HREF="xxfi_negotiate.html">negotiate</A>
274 this behavior with the MTA, i.e., it must check whether
275 the appropriate protocol action
276 <A HREF="xxfi_negotiate.html#SMFIP_NR_"><CODE>SMFIP_NR_*</CODE></A>
277 is available and if so, the milter must request it.
279 <A HREF="xxfi_negotiate.html#SMFIP_NR_"><CODE>SMFIP_NR_*</CODE></A>
280 protocol action for a callback, that callback <EM>must</EM>
283 Using any other reply code is a violation of the API.
284 If in some cases your callback may return another value
285 (e.g., due to some resource shortages), then you
286 <EM>must not</EM> set
287 <A HREF="xxfi_negotiate.html#SMFIP_NR_"><CODE>SMFIP_NR_*</CODE></A>
289 SMFIS_CONTINUE as the default return code.
290 (Alternatively you can try to delay reporting the problem to
291 a later callback for which
292 <A HREF="xxfi_negotiate.html#SMFIP_NR_"><CODE>SMFIP_NR_*</CODE></A>
299 <H2><A NAME="Miscellaneous">Miscellaneous</A></H2>
302 <TABLE BORDER="1" CELLSPACING=0 CELLPADDING=2><TR BGCOLOR="#dddddd"><TH>Function</TH><TH>Description</TH></TR>
304 <TR><TD><A HREF="smfi_version.html">smfi_version</A></TD><TD>libmilter (runtime) version info</TD></TR>
306 <TR><TD><A HREF="smfi_setsymlist.html">smfi_setsymlist</A></TD><TD>
307 Set the list of macros that the milter wants to receive from the MTA
308 for a protocol stage.
314 <TABLE BORDER="1" CELLSPACING=0 CELLPADDING=2><TR BGCOLOR="#dddddd"><TH>Constant</TH><TH>Description</TH></TR>
316 <TR><TD><A HREF="smfi_version.html">SMFI_VERSION</A></TD><TD>libmilter (compile time) version info</TD></TR>
323 Copyright (c) 2000, 2003, 2006, 2009 Proofpoint, Inc. and its suppliers.
326 By using this file, you agree to the terms and conditions set
327 forth in the LICENSE.