Training courses

Kernel and Embedded Linux

Bootlin training courses

Embedded Linux, kernel,
Yocto Project, Buildroot, real-time,
graphics, boot time, debugging...

Bootlin logo

Elixir Cross Referencer

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
/*	$NetBSD: proxymap.c,v 1.2 2017/02/14 01:16:47 christos Exp $	*/

/*++
/* NAME
/*	proxymap 8
/* SUMMARY
/*	Postfix lookup table proxy server
/* SYNOPSIS
/*	\fBproxymap\fR [generic Postfix daemon options]
/* DESCRIPTION
/*	The \fBproxymap\fR(8) server provides read-only or read-write
/*	table lookup service to Postfix processes. These services are
/*	implemented with distinct service names: \fBproxymap\fR and
/*	\fBproxywrite\fR, respectively. The purpose of these services is:
/* .IP \(bu
/*	To overcome chroot restrictions. For example, a chrooted SMTP
/*	server needs access to the system passwd file in order to
/*	reject mail for non-existent local addresses, but it is not
/*	practical to maintain a copy of the passwd file in the chroot
/*	jail.  The solution:
/* .sp
/* .nf
/*	local_recipient_maps =
/*	    proxy:unix:passwd.byname $alias_maps
/* .fi
/* .IP \(bu
/*	To consolidate the number of open lookup tables by sharing
/*	one open table among multiple processes. For example, making
/*	mysql connections from every Postfix daemon process results
/*	in "too many connections" errors. The solution:
/* .sp
/* .nf
/*	virtual_alias_maps =
/*	    proxy:mysql:/etc/postfix/virtual_alias.cf
/* .fi
/* .sp
/*	The total number of connections is limited by the number of
/*	proxymap server processes.
/* .IP \(bu
/*	To provide single-updater functionality for lookup tables
/*	that do not reliably support multiple writers (i.e. all
/*	file-based tables).
/* .PP
/*	The \fBproxymap\fR(8) server implements the following requests:
/* .IP "\fBopen\fR \fImaptype:mapname flags\fR"
/*	Open the table with type \fImaptype\fR and name \fImapname\fR,
/*	as controlled by \fIflags\fR. The reply includes the \fImaptype\fR
/*	dependent flags (to distinguish a fixed string table from a regular
/*	expression table).
/* .IP "\fBlookup\fR \fImaptype:mapname flags key\fR"
/*	Look up the data stored under the requested key.
/*	The reply is the request completion status code and
/*	the lookup result value.
/*	The \fImaptype:mapname\fR and \fIflags\fR are the same
/*	as with the \fBopen\fR request.
/* .IP "\fBupdate\fR \fImaptype:mapname flags key value\fR"
/*	Update the data stored under the requested key.
/*	The reply is the request completion status code.
/*	The \fImaptype:mapname\fR and \fIflags\fR are the same
/*	as with the \fBopen\fR request.
/* .sp
/*	To implement single-updater maps, specify a process limit
/*	of 1 in the master.cf file entry for the \fBproxywrite\fR
/*	service.
/* .sp
/*	This request is supported in Postfix 2.5 and later.
/* .IP "\fBdelete\fR \fImaptype:mapname flags key\fR"
/*	Delete the data stored under the requested key.
/*	The reply is the request completion status code.
/*	The \fImaptype:mapname\fR and \fIflags\fR are the same
/*	as with the \fBopen\fR request.
/* .sp
/*	This request is supported in Postfix 2.5 and later.
/* .IP "\fBsequence\fR \fImaptype:mapname flags function\fR"
/*	Iterate over the specified database. The \fIfunction\fR
/*	is one of DICT_SEQ_FUN_FIRST or DICT_SEQ_FUN_NEXT.
/*	The reply is the request completion status code and
/*	a lookup key and result value, if found.
/* .sp
/*	This request is supported in Postfix 2.9 and later.
/* .PP
/*	The request completion status is one of OK, RETRY, NOKEY
/*	(lookup failed because the key was not found), BAD (malformed
/*	request) or DENY (the table is not approved for proxy read
/*	or update access).
/*
/*	There is no \fBclose\fR command, nor are tables implicitly closed
/*	when a client disconnects. The purpose is to share tables among
/*	multiple client processes.
/* SERVER PROCESS MANAGEMENT
/* .ad
/* .fi
/*	\fBproxymap\fR(8) servers run under control by the Postfix
/*	\fBmaster\fR(8)
/*	server.  Each server can handle multiple simultaneous connections.
/*	When all servers are busy while a client connects, the \fBmaster\fR(8)
/*	creates a new \fBproxymap\fR(8) server process, provided that the
/*	process limit is not exceeded.
/*	Each server terminates after serving at least \fB$max_use\fR clients
/*	or after \fB$max_idle\fR seconds of idle time.
/* SECURITY
/* .ad
/* .fi
/*	The \fBproxymap\fR(8) server opens only tables that are
/*	approved via the \fBproxy_read_maps\fR or \fBproxy_write_maps\fR
/*	configuration parameters, does not talk to
/*	users, and can run at fixed low privilege, chrooted or not.
/*	However, running the proxymap server chrooted severely limits
/*	usability, because it can open only chrooted tables.
/*
/*	The \fBproxymap\fR(8) server is not a trusted daemon process, and must
/*	not be used to look up sensitive information such as UNIX user or
/*	group IDs, mailbox file/directory names or external commands.
/*
/*	In Postfix version 2.2 and later, the proxymap client recognizes
/*	requests to access a table for security-sensitive purposes,
/*	and opens the table directly. This allows the same main.cf
/*	setting to be used by sensitive and non-sensitive processes.
/*
/*	Postfix-writable data files should be stored under a dedicated
/*	directory that is writable only by the Postfix mail system,
/*	such as the Postfix-owned \fBdata_directory\fR.
/*
/*	In particular, Postfix-writable files should never exist
/*	in root-owned directories. That would open up a particular
/*	type of security hole where ownership of a file or directory
/*	does not match the provider of its content.
/* DIAGNOSTICS
/*	Problems and transactions are logged to \fBsyslogd\fR(8).
/* BUGS
/*	The \fBproxymap\fR(8) server provides service to multiple clients,
/*	and must therefore not be used for tables that have high-latency
/*	lookups.
/*
/*	The \fBproxymap\fR(8) read-write service does not explicitly
/*	close lookup tables (even if it did, this could not be relied on,
/*	because the process may be terminated between table updates).
/*	The read-write service should therefore not be used with tables that
/*	leave persistent storage in an inconsistent state between
/*	updates (for example, CDB). Tables that support "sync on
/*	update" should be safe (for example, Berkeley DB) as should
/*	tables that are implemented by a real DBMS.
/* CONFIGURATION PARAMETERS
/* .ad
/* .fi
/*	On busy mail systems a long time may pass before
/*	\fBproxymap\fR(8) relevant
/*	changes to \fBmain.cf\fR are picked up. Use the command
/*	"\fBpostfix reload\fR" to speed up a change.
/*
/*	The text below provides only a parameter summary. See
/*	\fBpostconf\fR(5) for more details including examples.
/* .IP "\fBconfig_directory (see 'postconf -d' output)\fR"
/*	The default location of the Postfix main.cf and master.cf
/*	configuration files.
/* .IP "\fBdata_directory (see 'postconf -d' output)\fR"
/*	The directory with Postfix-writable data files (for example:
/*	caches, pseudo-random numbers).
/* .IP "\fBdaemon_timeout (18000s)\fR"
/*	How much time a Postfix daemon process may take to handle a
/*	request before it is terminated by a built-in watchdog timer.
/* .IP "\fBipc_timeout (3600s)\fR"
/*	The time limit for sending or receiving information over an internal
/*	communication channel.
/* .IP "\fBmax_idle (100s)\fR"
/*	The maximum amount of time that an idle Postfix daemon process waits
/*	for an incoming connection before terminating voluntarily.
/* .IP "\fBmax_use (100)\fR"
/*	The maximal number of incoming connections that a Postfix daemon
/*	process will service before terminating voluntarily.
/* .IP "\fBprocess_id (read-only)\fR"
/*	The process ID of a Postfix command or daemon process.
/* .IP "\fBprocess_name (read-only)\fR"
/*	The process name of a Postfix command or daemon process.
/* .IP "\fBproxy_read_maps (see 'postconf -d' output)\fR"
/*	The lookup tables that the \fBproxymap\fR(8) server is allowed to
/*	access for the read-only service.
/* .PP
/*	Available in Postfix 2.5 and later:
/* .IP "\fBdata_directory (see 'postconf -d' output)\fR"
/*	The directory with Postfix-writable data files (for example:
/*	caches, pseudo-random numbers).
/* .IP "\fBproxy_write_maps (see 'postconf -d' output)\fR"
/*	The lookup tables that the \fBproxymap\fR(8) server is allowed to
/*	access for the read-write service.
/* SEE ALSO
/*	postconf(5), configuration parameters
/*	master(5), generic daemon options
/* README FILES
/* .ad
/* .fi
/*	Use "\fBpostconf readme_directory\fR" or
/*	"\fBpostconf html_directory\fR" to locate this information.
/* .na
/* .nf
/*	DATABASE_README, Postfix lookup table overview
/* LICENSE
/* .ad
/* .fi
/*	The Secure Mailer license must be distributed with this software.
/* HISTORY
/* .ad
/* .fi
/*	The proxymap service was introduced with Postfix 2.0.
/* AUTHOR(S)
/*	Wietse Venema
/*	IBM T.J. Watson Research
/*	P.O. Box 704
/*	Yorktown Heights, NY 10598, USA
/*
/*	Wietse Venema
/*	Google, Inc.
/*	111 8th Avenue
/*	New York, NY 10011, USA
/*--*/

/* System library. */

#include <sys_defs.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>

/* Utility library. */

#include <msg.h>
#include <mymalloc.h>
#include <vstring.h>
#include <htable.h>
#include <stringops.h>
#include <dict.h>

/* Global library. */

#include <mail_conf.h>
#include <mail_params.h>
#include <mail_version.h>
#include <mail_proto.h>
#include <dict_proxy.h>

/* Server skeleton. */

#include <mail_server.h>

/* Application-specific. */

 /*
  * XXX All but the last are needed here so that $name expansion dependencies
  * aren't too broken. The fix is to gather all parameter default settings in
  * one place.
  */
char   *var_alias_maps;
char   *var_local_rcpt_maps;
char   *var_virt_alias_maps;
char   *var_virt_alias_doms;
char   *var_virt_mailbox_maps;
char   *var_virt_mailbox_doms;
char   *var_relay_rcpt_maps;
char   *var_relay_domains;
char   *var_canonical_maps;
char   *var_send_canon_maps;
char   *var_rcpt_canon_maps;
char   *var_relocated_maps;
char   *var_transport_maps;
char   *var_verify_map;
char   *var_smtpd_snd_auth_maps;
char   *var_psc_cache_map;
char   *var_proxy_read_maps;
char   *var_proxy_write_maps;

 /*
  * The pre-approved, pre-parsed list of maps.
  */
static HTABLE *proxy_auth_maps;

 /*
  * Shared and static to reduce memory allocation overhead.
  */
static VSTRING *request;
static VSTRING *request_map;
static VSTRING *request_key;
static VSTRING *request_value;
static VSTRING *map_type_name_flags;

 /*
  * Are we a proxy writer or not?
  */
static int proxy_writer;

 /*
  * Silly little macros.
  */
#define STR(x)			vstring_str(x)
#define VSTREQ(x,y)		(strcmp(STR(x),y) == 0)

/* proxy_map_find - look up or open table */

static DICT *proxy_map_find(const char *map_type_name, int request_flags,
			            int *statp)
{
    DICT   *dict;

#define PROXY_COLON	DICT_TYPE_PROXY ":"
#define PROXY_COLON_LEN	(sizeof(PROXY_COLON) - 1)
#define READ_OPEN_FLAGS	O_RDONLY
#define WRITE_OPEN_FLAGS (O_RDWR | O_CREAT)

    /*
     * Canonicalize the map name. If the map is not on the approved list,
     * deny the request.
     */
#define PROXY_MAP_FIND_ERROR_RETURN(x)  { *statp = (x); return (0); }

    while (strncmp(map_type_name, PROXY_COLON, PROXY_COLON_LEN) == 0)
	map_type_name += PROXY_COLON_LEN;
    /* XXX The following breaks with maps that have ':' in their name. */
    if (strchr(map_type_name, ':') == 0)
	PROXY_MAP_FIND_ERROR_RETURN(PROXY_STAT_BAD);
    if (htable_locate(proxy_auth_maps, map_type_name) == 0) {
	msg_warn("request for unapproved table: \"%s\"", map_type_name);
	msg_warn("to approve this table for %s access, list %s:%s in %s:%s",
		 proxy_writer == 0 ? "read-only" : "read-write",
		 DICT_TYPE_PROXY, map_type_name, MAIN_CONF_FILE,
		 proxy_writer == 0 ? VAR_PROXY_READ_MAPS :
		 VAR_PROXY_WRITE_MAPS);
	PROXY_MAP_FIND_ERROR_RETURN(PROXY_STAT_DENY);
    }

    /*
     * Open one instance of a map for each combination of name+flags.
     * 
     * Assume that a map instance can be shared among clients with different
     * paranoia flag settings and with different map lookup flag settings.
     * 
     * XXX The open() flags are passed implicitly, via the selection of the
     * service name. For a more sophisticated interface, appropriate subsets
     * of open() flags should be received directly from the client.
     */
    vstring_sprintf(map_type_name_flags, "%s:%s", map_type_name,
		    dict_flags_str(request_flags & DICT_FLAG_INST_MASK));
    if (msg_verbose)
	msg_info("proxy_map_find: %s", STR(map_type_name_flags));
    if ((dict = dict_handle(STR(map_type_name_flags))) == 0) {
	dict = dict_open(map_type_name, proxy_writer ?
			 WRITE_OPEN_FLAGS : READ_OPEN_FLAGS,
			 request_flags);
	if (dict == 0)
	    msg_panic("proxy_map_find: dict_open null result");
	dict_register(STR(map_type_name_flags), dict);
    }
    dict->error = 0;
    return (dict);
}

/* proxymap_sequence_service - remote sequence service */

static void proxymap_sequence_service(VSTREAM *client_stream)
{
    int     request_flags;
    DICT   *dict;
    int     request_func;
    const char *reply_key;
    const char *reply_value;
    int     dict_status;
    int     reply_status;

    /*
     * Process the request.
     */
    if (attr_scan(client_stream, ATTR_FLAG_STRICT,
		  RECV_ATTR_STR(MAIL_ATTR_TABLE, request_map),
		  RECV_ATTR_INT(MAIL_ATTR_FLAGS, &request_flags),
		  RECV_ATTR_INT(MAIL_ATTR_FUNC, &request_func),
		  ATTR_TYPE_END) != 3
	|| (request_func != DICT_SEQ_FUN_FIRST
	    && request_func != DICT_SEQ_FUN_NEXT)) {
	reply_status = PROXY_STAT_BAD;
	reply_key = reply_value = "";
    } else if ((dict = proxy_map_find(STR(request_map), request_flags,
				      &reply_status)) == 0) {
	reply_key = reply_value = "";
    } else {
	dict->flags = ((dict->flags & ~DICT_FLAG_RQST_MASK)
		       | (request_flags & DICT_FLAG_RQST_MASK));
	dict_status = dict_seq(dict, request_func, &reply_key, &reply_value);
	if (dict_status == 0) {
	    reply_status = PROXY_STAT_OK;
	} else if (dict->error == 0) {
	    reply_status = PROXY_STAT_NOKEY;
	    reply_key = reply_value = "";
	} else {
	    reply_status = (dict->error == DICT_ERR_RETRY ?
			    PROXY_STAT_RETRY : PROXY_STAT_CONFIG);
	    reply_key = reply_value = "";
	}
    }

    /*
     * Respond to the client.
     */
    attr_print(client_stream, ATTR_FLAG_NONE,
	       SEND_ATTR_INT(MAIL_ATTR_STATUS, reply_status),
	       SEND_ATTR_STR(MAIL_ATTR_KEY, reply_key),
	       SEND_ATTR_STR(MAIL_ATTR_VALUE, reply_value),
	       ATTR_TYPE_END);
}

/* proxymap_lookup_service - remote lookup service */

static void proxymap_lookup_service(VSTREAM *client_stream)
{
    int     request_flags;
    DICT   *dict;
    const char *reply_value;
    int     reply_status;

    /*
     * Process the request.
     */
    if (attr_scan(client_stream, ATTR_FLAG_STRICT,
		  RECV_ATTR_STR(MAIL_ATTR_TABLE, request_map),
		  RECV_ATTR_INT(MAIL_ATTR_FLAGS, &request_flags),
		  RECV_ATTR_STR(MAIL_ATTR_KEY, request_key),
		  ATTR_TYPE_END) != 3) {
	reply_status = PROXY_STAT_BAD;
	reply_value = "";
    } else if ((dict = proxy_map_find(STR(request_map), request_flags,
				      &reply_status)) == 0) {
	reply_value = "";
    } else if (dict->flags = ((dict->flags & ~DICT_FLAG_RQST_MASK)
			      | (request_flags & DICT_FLAG_RQST_MASK)),
	       (reply_value = dict_get(dict, STR(request_key))) != 0) {
	reply_status = PROXY_STAT_OK;
    } else if (dict->error == 0) {
	reply_status = PROXY_STAT_NOKEY;
	reply_value = "";
    } else {
	reply_status = (dict->error == DICT_ERR_RETRY ?
			PROXY_STAT_RETRY : PROXY_STAT_CONFIG);
	reply_value = "";
    }

    /*
     * Respond to the client.
     */
    attr_print(client_stream, ATTR_FLAG_NONE,
	       SEND_ATTR_INT(MAIL_ATTR_STATUS, reply_status),
	       SEND_ATTR_STR(MAIL_ATTR_VALUE, reply_value),
	       ATTR_TYPE_END);
}

/* proxymap_update_service - remote update service */

static void proxymap_update_service(VSTREAM *client_stream)
{
    int     request_flags;
    DICT   *dict;
    int     dict_status;
    int     reply_status;

    /*
     * Process the request.
     * 
     * XXX We don't close maps, so we must turn on synchronous update to ensure
     * that the on-disk data is in a consistent state between updates.
     * 
     * XXX We ignore duplicates, because the proxymap server would abort
     * otherwise.
     */
    if (attr_scan(client_stream, ATTR_FLAG_STRICT,
		  RECV_ATTR_STR(MAIL_ATTR_TABLE, request_map),
		  RECV_ATTR_INT(MAIL_ATTR_FLAGS, &request_flags),
		  RECV_ATTR_STR(MAIL_ATTR_KEY, request_key),
		  RECV_ATTR_STR(MAIL_ATTR_VALUE, request_value),
		  ATTR_TYPE_END) != 4) {
	reply_status = PROXY_STAT_BAD;
    } else if (proxy_writer == 0) {
	msg_warn("refusing %s update request on non-%s service",
		 STR(request_map), MAIL_SERVICE_PROXYWRITE);
	reply_status = PROXY_STAT_DENY;
    } else if ((dict = proxy_map_find(STR(request_map), request_flags,
				      &reply_status)) == 0) {
	 /* void */ ;
    } else {
	dict->flags = ((dict->flags & ~DICT_FLAG_RQST_MASK)
		       | (request_flags & DICT_FLAG_RQST_MASK)
		       | DICT_FLAG_SYNC_UPDATE | DICT_FLAG_DUP_REPLACE);
	dict_status = dict_put(dict, STR(request_key), STR(request_value));
	if (dict_status == 0) {
	    reply_status = PROXY_STAT_OK;
	} else if (dict->error == 0) {
	    reply_status = PROXY_STAT_NOKEY;
	} else {
	    reply_status = (dict->error == DICT_ERR_RETRY ?
			    PROXY_STAT_RETRY : PROXY_STAT_CONFIG);
	}
    }

    /*
     * Respond to the client.
     */
    attr_print(client_stream, ATTR_FLAG_NONE,
	       SEND_ATTR_INT(MAIL_ATTR_STATUS, reply_status),
	       ATTR_TYPE_END);
}

/* proxymap_delete_service - remote delete service */

static void proxymap_delete_service(VSTREAM *client_stream)
{
    int     request_flags;
    DICT   *dict;
    int     dict_status;
    int     reply_status;

    /*
     * Process the request.
     * 
     * XXX We don't close maps, so we must turn on synchronous update to ensure
     * that the on-disk data is in a consistent state between updates.
     */
    if (attr_scan(client_stream, ATTR_FLAG_STRICT,
		  RECV_ATTR_STR(MAIL_ATTR_TABLE, request_map),
		  RECV_ATTR_INT(MAIL_ATTR_FLAGS, &request_flags),
		  RECV_ATTR_STR(MAIL_ATTR_KEY, request_key),
		  ATTR_TYPE_END) != 3) {
	reply_status = PROXY_STAT_BAD;
    } else if (proxy_writer == 0) {
	msg_warn("refusing %s delete request on non-%s service",
		 STR(request_map), MAIL_SERVICE_PROXYWRITE);
	reply_status = PROXY_STAT_DENY;
    } else if ((dict = proxy_map_find(STR(request_map), request_flags,
				      &reply_status)) == 0) {
	 /* void */ ;
    } else {
	dict->flags = ((dict->flags & ~DICT_FLAG_RQST_MASK)
		       | (request_flags & DICT_FLAG_RQST_MASK)
		       | DICT_FLAG_SYNC_UPDATE);
	dict_status = dict_del(dict, STR(request_key));
	if (dict_status == 0) {
	    reply_status = PROXY_STAT_OK;
	} else if (dict->error == 0) {
	    reply_status = PROXY_STAT_NOKEY;
	} else {
	    reply_status = (dict->error == DICT_ERR_RETRY ?
			    PROXY_STAT_RETRY : PROXY_STAT_CONFIG);
	}
    }

    /*
     * Respond to the client.
     */
    attr_print(client_stream, ATTR_FLAG_NONE,
	       SEND_ATTR_INT(MAIL_ATTR_STATUS, reply_status),
	       ATTR_TYPE_END);
}

/* proxymap_open_service - open remote lookup table */

static void proxymap_open_service(VSTREAM *client_stream)
{
    int     request_flags;
    DICT   *dict;
    int     reply_status;
    int     reply_flags;

    /*
     * Process the request.
     */
    if (attr_scan(client_stream, ATTR_FLAG_STRICT,
		  RECV_ATTR_STR(MAIL_ATTR_TABLE, request_map),
		  RECV_ATTR_INT(MAIL_ATTR_FLAGS, &request_flags),
		  ATTR_TYPE_END) != 2) {
	reply_status = PROXY_STAT_BAD;
	reply_flags = 0;
    } else if ((dict = proxy_map_find(STR(request_map), request_flags,
				      &reply_status)) == 0) {
	reply_flags = 0;
    } else {
	reply_status = PROXY_STAT_OK;
	reply_flags = dict->flags;
    }

    /*
     * Respond to the client.
     */
    attr_print(client_stream, ATTR_FLAG_NONE,
	       SEND_ATTR_INT(MAIL_ATTR_STATUS, reply_status),
	       SEND_ATTR_INT(MAIL_ATTR_FLAGS, reply_flags),
	       ATTR_TYPE_END);
}

/* proxymap_service - perform service for client */

static void proxymap_service(VSTREAM *client_stream, char *unused_service,
			             char **argv)
{

    /*
     * Sanity check. This service takes no command-line arguments.
     */
    if (argv[0])
	msg_fatal("unexpected command-line argument: %s", argv[0]);

    /*
     * Deadline enforcement.
     */
    if (vstream_fstat(client_stream, VSTREAM_FLAG_DEADLINE) == 0)
	vstream_control(client_stream,
			CA_VSTREAM_CTL_TIMEOUT(1),
			CA_VSTREAM_CTL_END);

    /*
     * This routine runs whenever a client connects to the socket dedicated
     * to the proxymap service. All connection-management stuff is handled by
     * the common code in multi_server.c.
     */
    vstream_control(client_stream,
		    CA_VSTREAM_CTL_START_DEADLINE,
		    CA_VSTREAM_CTL_END);
    if (attr_scan(client_stream,
		  ATTR_FLAG_MORE | ATTR_FLAG_STRICT,
		  RECV_ATTR_STR(MAIL_ATTR_REQ, request),
		  ATTR_TYPE_END) == 1) {
	if (VSTREQ(request, PROXY_REQ_LOOKUP)) {
	    proxymap_lookup_service(client_stream);
	} else if (VSTREQ(request, PROXY_REQ_UPDATE)) {
	    proxymap_update_service(client_stream);
	} else if (VSTREQ(request, PROXY_REQ_DELETE)) {
	    proxymap_delete_service(client_stream);
	} else if (VSTREQ(request, PROXY_REQ_SEQUENCE)) {
	    proxymap_sequence_service(client_stream);
	} else if (VSTREQ(request, PROXY_REQ_OPEN)) {
	    proxymap_open_service(client_stream);
	} else {
	    msg_warn("unrecognized request: \"%s\", ignored", STR(request));
	    attr_print(client_stream, ATTR_FLAG_NONE,
		       SEND_ATTR_INT(MAIL_ATTR_STATUS, PROXY_STAT_BAD),
		       ATTR_TYPE_END);
	}
    }
    vstream_control(client_stream,
		    CA_VSTREAM_CTL_START_DEADLINE,
		    CA_VSTREAM_CTL_END);
    vstream_fflush(client_stream);
}

/* dict_proxy_open - intercept remote map request from inside library */

DICT   *dict_proxy_open(const char *map, int open_flags, int dict_flags)
{
    if (msg_verbose)
	msg_info("dict_proxy_open(%s, 0%o, 0%o) called from internal routine",
		 map, open_flags, dict_flags);
    while (strncmp(map, PROXY_COLON, PROXY_COLON_LEN) == 0)
	map += PROXY_COLON_LEN;
    return (dict_open(map, open_flags, dict_flags));
}

/* post_jail_init - initialization after privilege drop */

static void post_jail_init(char *service_name, char **unused_argv)
{
    const char *sep = CHARS_COMMA_SP;
    const char *parens = CHARS_BRACE;
    char   *saved_filter;
    char   *bp;
    char   *type_name;

    /*
     * Are we proxy writer?
     */
    if (strcmp(service_name, MAIL_SERVICE_PROXYWRITE) == 0)
	proxy_writer = 1;
    else if (strcmp(service_name, MAIL_SERVICE_PROXYMAP) != 0)
	msg_fatal("service name must be one of %s or %s",
		  MAIL_SERVICE_PROXYMAP, MAIL_SERVICE_PROXYMAP);

    /*
     * Pre-allocate buffers.
     */
    request = vstring_alloc(10);
    request_map = vstring_alloc(10);
    request_key = vstring_alloc(10);
    request_value = vstring_alloc(10);
    map_type_name_flags = vstring_alloc(10);

    /*
     * Prepare the pre-approved list of proxied tables.
     */
    saved_filter = bp = mystrdup(proxy_writer ? var_proxy_write_maps :
				 var_proxy_read_maps);
    proxy_auth_maps = htable_create(13);
    while ((type_name = mystrtokq(&bp, sep, parens)) != 0) {
	if (strncmp(type_name, PROXY_COLON, PROXY_COLON_LEN))
	    continue;
	do {
	    type_name += PROXY_COLON_LEN;
	} while (!strncmp(type_name, PROXY_COLON, PROXY_COLON_LEN));
	if (strchr(type_name, ':') != 0
	    && htable_locate(proxy_auth_maps, type_name) == 0)
	    (void) htable_enter(proxy_auth_maps, type_name, (void *) 0);
    }
    myfree(saved_filter);

    /*
     * Never, ever, get killed by a master signal, as that could corrupt a
     * persistent database when we're in the middle of an update.
     */
    if (proxy_writer != 0)
	setsid();
}

/* pre_accept - see if tables have changed */

static void pre_accept(char *unused_name, char **unused_argv)
{
    const char *table;

    if (proxy_writer == 0 && (table = dict_changed_name()) != 0) {
	msg_info("table %s has changed -- restarting", table);
	exit(0);
    }
}

MAIL_VERSION_STAMP_DECLARE;

/* main - pass control to the multi-threaded skeleton */

int     main(int argc, char **argv)
{
    static const CONFIG_STR_TABLE str_table[] = {
	VAR_ALIAS_MAPS, DEF_ALIAS_MAPS, &var_alias_maps, 0, 0,
	VAR_LOCAL_RCPT_MAPS, DEF_LOCAL_RCPT_MAPS, &var_local_rcpt_maps, 0, 0,
	VAR_VIRT_ALIAS_MAPS, DEF_VIRT_ALIAS_MAPS, &var_virt_alias_maps, 0, 0,
	VAR_VIRT_ALIAS_DOMS, DEF_VIRT_ALIAS_DOMS, &var_virt_alias_doms, 0, 0,
	VAR_VIRT_MAILBOX_MAPS, DEF_VIRT_MAILBOX_MAPS, &var_virt_mailbox_maps, 0, 0,
	VAR_VIRT_MAILBOX_DOMS, DEF_VIRT_MAILBOX_DOMS, &var_virt_mailbox_doms, 0, 0,
	VAR_RELAY_RCPT_MAPS, DEF_RELAY_RCPT_MAPS, &var_relay_rcpt_maps, 0, 0,
	VAR_RELAY_DOMAINS, DEF_RELAY_DOMAINS, &var_relay_domains, 0, 0,
	VAR_CANONICAL_MAPS, DEF_CANONICAL_MAPS, &var_canonical_maps, 0, 0,
	VAR_SEND_CANON_MAPS, DEF_SEND_CANON_MAPS, &var_send_canon_maps, 0, 0,
	VAR_RCPT_CANON_MAPS, DEF_RCPT_CANON_MAPS, &var_rcpt_canon_maps, 0, 0,
	VAR_RELOCATED_MAPS, DEF_RELOCATED_MAPS, &var_relocated_maps, 0, 0,
	VAR_TRANSPORT_MAPS, DEF_TRANSPORT_MAPS, &var_transport_maps, 0, 0,
	VAR_VERIFY_MAP, DEF_VERIFY_MAP, &var_verify_map, 0, 0,
	VAR_SMTPD_SND_AUTH_MAPS, DEF_SMTPD_SND_AUTH_MAPS, &var_smtpd_snd_auth_maps, 0, 0,
	VAR_PSC_CACHE_MAP, DEF_PSC_CACHE_MAP, &var_psc_cache_map, 0, 0,
	/* The following two must be last for $mapname to work as expected. */
	VAR_PROXY_READ_MAPS, DEF_PROXY_READ_MAPS, &var_proxy_read_maps, 0, 0,
	VAR_PROXY_WRITE_MAPS, DEF_PROXY_WRITE_MAPS, &var_proxy_write_maps, 0, 0,
	0,
    };

    /*
     * Fingerprint executables and core dumps.
     */
    MAIL_VERSION_STAMP_ALLOCATE;

    multi_server_main(argc, argv, proxymap_service,
		      CA_MAIL_SERVER_STR_TABLE(str_table),
		      CA_MAIL_SERVER_POST_INIT(post_jail_init),
		      CA_MAIL_SERVER_PRE_ACCEPT(pre_accept),
    /* XXX CA_MAIL_SERVER_SOLITARY if proxywrite */
		      0);
}