/* $NetBSD: scache.c,v 1.4 2022/10/08 16:12:49 christos Exp $ */
/*++
/* NAME
/* scache 8
/* SUMMARY
/* Postfix shared connection cache server
/* SYNOPSIS
/* \fBscache\fR [generic Postfix daemon options]
/* DESCRIPTION
/* The \fBscache\fR(8) server maintains a shared multi-connection
/* cache. This information can be used by, for example, Postfix
/* SMTP clients or other Postfix delivery agents.
/*
/* The connection cache is organized into logical destination
/* names, physical endpoint names, and connections.
/*
/* As a specific example, logical SMTP destinations specify
/* (transport, domain, port), and physical SMTP endpoints
/* specify (transport, IP address, port). An SMTP connection
/* may be saved after a successful mail transaction.
/*
/* In the general case, one logical destination may refer to
/* zero or more physical endpoints, one physical endpoint may
/* be referenced by zero or more logical destinations, and
/* one endpoint may refer to zero or more connections.
/*
/* The exact syntax of a logical destination or endpoint name
/* is application dependent; the \fBscache\fR(8) server does
/* not care. A connection is stored as a file descriptor together
/* with application-dependent information that is needed to
/* re-activate a connection object. Again, the \fBscache\fR(8)
/* server is completely unaware of the details of that
/* information.
/*
/* All information is stored with a finite time to live (ttl).
/* The connection cache daemon terminates when no client is
/* connected for \fBmax_idle\fR time units.
/*
/* This server implements the following requests:
/* .IP "\fBsave_endp\fI ttl endpoint endpoint_properties file_descriptor\fR"
/* Save the specified file descriptor and connection property data
/* under the specified endpoint name. The endpoint properties
/* are used by the client to re-activate a passivated connection
/* object.
/* .IP "\fBfind_endp\fI endpoint\fR"
/* Look up cached properties and a cached file descriptor for the
/* specified endpoint.
/* .IP "\fBsave_dest\fI ttl destination destination_properties endpoint\fR"
/* Save the binding between a logical destination and an
/* endpoint under the destination name, together with destination
/* specific connection properties. The destination properties
/* are used by the client to re-activate a passivated connection
/* object.
/* .IP "\fBfind_dest\fI destination\fR"
/* Look up cached destination properties, cached endpoint properties,
/* and a cached file descriptor for the specified logical destination.
/* SECURITY
/* .ad
/* .fi
/* The \fBscache\fR(8) server is not security-sensitive. It does not
/* talk to the network, and it does not talk to local users.
/* The \fBscache\fR(8) server can run chrooted at fixed low privilege.
/*
/* The \fBscache\fR(8) server is not a trusted process. It must
/* not be used to store information that is security sensitive.
/* DIAGNOSTICS
/* Problems and transactions are logged to \fBsyslogd\fR(8)
/* or \fBpostlogd\fR(8).
/* BUGS
/* The session cache cannot be shared among multiple machines.
/*
/* When a connection expires from the cache, it is closed without
/* the appropriate protocol specific handshake.
/* CONFIGURATION PARAMETERS
/* .ad
/* .fi
/* Changes to \fBmain.cf\fR are picked up automatically as \fBscache\fR(8)
/* processes run for only a limited amount of time. 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.
/* RESOURCE CONTROLS
/* .ad
/* .fi
/* .IP "\fBconnection_cache_ttl_limit (2s)\fR"
/* The maximal time-to-live value that the \fBscache\fR(8) connection
/* cache server
/* allows.
/* .IP "\fBconnection_cache_status_update_time (600s)\fR"
/* How frequently the \fBscache\fR(8) server logs usage statistics with
/* connection cache hit and miss rates for logical destinations and for
/* physical endpoints.
/* MISCELLANEOUS CONTROLS
/* .ad
/* .fi
/* .IP "\fBconfig_directory (see 'postconf -d' output)\fR"
/* The default location of the Postfix main.cf and master.cf
/* configuration files.
/* .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 "\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 "\fBsyslog_facility (mail)\fR"
/* The syslog facility of Postfix logging.
/* .IP "\fBsyslog_name (see 'postconf -d' output)\fR"
/* A prefix that is prepended to the process name in syslog
/* records, so that, for example, "smtpd" becomes "prefix/smtpd".
/* .PP
/* Available in Postfix 3.3 and later:
/* .IP "\fBservice_name (read-only)\fR"
/* The master.cf service name of a Postfix daemon process.
/* SEE ALSO
/* smtp(8), SMTP client
/* postconf(5), configuration parameters
/* master(8), process manager
/* postlogd(8), Postfix logging
/* syslogd(8), system logging
/* README FILES
/* .ad
/* .fi
/* Use "\fBpostconf readme_directory\fR" or
/* "\fBpostconf html_directory\fR" to locate this information.
/* .na
/* .nf
/* CONNECTION_CACHE_README, Postfix connection cache
/* LICENSE
/* .ad
/* .fi
/* The Secure Mailer license must be distributed with this software.
/* HISTORY
/* This service was introduced with Postfix version 2.2.
/* 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 <time.h>
/* Utility library. */
#include <msg.h>
#include <iostuff.h>
#include <htable.h>
#include <ring.h>
#include <events.h>
/* Global library. */
#include <mail_params.h>
#include <mail_version.h>
#include <mail_proto.h>
#include <scache.h>
/* Single server skeleton. */
#include <mail_server.h>
#include <mail_conf.h>
/* Application-specific. */
/*
* Tunable parameters.
*/
int var_scache_ttl_lim;
int var_scache_stat_time;
/*
* Request parameters.
*/
static VSTRING *scache_request;
static VSTRING *scache_dest_label;
static VSTRING *scache_dest_prop;
static VSTRING *scache_endp_label;
static VSTRING *scache_endp_prop;
#ifdef CANT_WRITE_BEFORE_SENDING_FD
static VSTRING *scache_dummy;
#endif
/*
* Session cache instance.
*/
static SCACHE *scache;
/*
* Statistics.
*/
static int scache_dest_hits;
static int scache_dest_miss;
static int scache_dest_count;
static int scache_endp_hits;
static int scache_endp_miss;
static int scache_endp_count;
static int scache_sess_count;
time_t scache_start_time;
/*
* Silly little macros.
*/
#define STR(x) vstring_str(x)
#define VSTREQ(x,y) (strcmp(STR(x),y) == 0)
/* scache_save_endp_service - protocol to save endpoint->stream binding */
static void scache_save_endp_service(VSTREAM *client_stream)
{
const char *myname = "scache_save_endp_service";
int ttl;
int fd;
SCACHE_SIZE size;
if (attr_scan(client_stream,
ATTR_FLAG_STRICT,
RECV_ATTR_INT(MAIL_ATTR_TTL, &ttl),
RECV_ATTR_STR(MAIL_ATTR_LABEL, scache_endp_label),
RECV_ATTR_STR(MAIL_ATTR_PROP, scache_endp_prop),
ATTR_TYPE_END) != 3
|| ttl <= 0) {
msg_warn("%s: bad or missing request parameter", myname);
attr_print(client_stream, ATTR_FLAG_NONE,
SEND_ATTR_INT(MAIL_ATTR_STATUS, SCACHE_STAT_BAD),
ATTR_TYPE_END);
return;
} else if (
#ifdef CANT_WRITE_BEFORE_SENDING_FD
attr_print(client_stream, ATTR_FLAG_NONE,
SEND_ATTR_STR(MAIL_ATTR_DUMMY, ""),
ATTR_TYPE_END) != 0
|| vstream_fflush(client_stream) != 0
|| read_wait(vstream_fileno(client_stream),
client_stream->timeout) < 0 /* XXX */
||
#endif
(fd = LOCAL_RECV_FD(vstream_fileno(client_stream))) < 0) {
msg_warn("%s: unable to receive file descriptor: %m", myname);
(void) attr_print(client_stream, ATTR_FLAG_NONE,
SEND_ATTR_INT(MAIL_ATTR_STATUS, SCACHE_STAT_FAIL),
ATTR_TYPE_END);
return;
} else {
scache_save_endp(scache,
ttl > var_scache_ttl_lim ? var_scache_ttl_lim : ttl,
STR(scache_endp_label), STR(scache_endp_prop), fd);
(void) attr_print(client_stream, ATTR_FLAG_NONE,
SEND_ATTR_INT(MAIL_ATTR_STATUS, SCACHE_STAT_OK),
ATTR_TYPE_END);
scache_size(scache, &size);
if (size.endp_count > scache_endp_count)
scache_endp_count = size.endp_count;
if (size.sess_count > scache_sess_count)
scache_sess_count = size.sess_count;
return;
}
}
/* scache_find_endp_service - protocol to find connection for endpoint */
static void scache_find_endp_service(VSTREAM *client_stream)
{
const char *myname = "scache_find_endp_service";
int fd;
if (attr_scan(client_stream,
ATTR_FLAG_STRICT,
RECV_ATTR_STR(MAIL_ATTR_LABEL, scache_endp_label),
ATTR_TYPE_END) != 1) {
msg_warn("%s: bad or missing request parameter", myname);
attr_print(client_stream, ATTR_FLAG_NONE,
SEND_ATTR_INT(MAIL_ATTR_STATUS, SCACHE_STAT_BAD),
SEND_ATTR_STR(MAIL_ATTR_PROP, ""),
ATTR_TYPE_END);
return;
} else if ((fd = scache_find_endp(scache, STR(scache_endp_label),
scache_endp_prop)) < 0) {
attr_print(client_stream, ATTR_FLAG_NONE,
SEND_ATTR_INT(MAIL_ATTR_STATUS, SCACHE_STAT_FAIL),
SEND_ATTR_STR(MAIL_ATTR_PROP, ""),
ATTR_TYPE_END);
scache_endp_miss++;
return;
} else {
attr_print(client_stream, ATTR_FLAG_NONE,
SEND_ATTR_INT(MAIL_ATTR_STATUS, SCACHE_STAT_OK),
SEND_ATTR_STR(MAIL_ATTR_PROP, STR(scache_endp_prop)),
ATTR_TYPE_END);
if (vstream_fflush(client_stream) != 0
#ifdef CANT_WRITE_BEFORE_SENDING_FD
|| attr_scan(client_stream, ATTR_FLAG_STRICT,
RECV_ATTR_STR(MAIL_ATTR_DUMMY, scache_dummy),
ATTR_TYPE_END) != 1
#endif
|| LOCAL_SEND_FD(vstream_fileno(client_stream), fd) < 0
#ifdef MUST_READ_AFTER_SENDING_FD
|| attr_scan(client_stream, ATTR_FLAG_STRICT,
RECV_ATTR_STR(MAIL_ATTR_DUMMY, scache_dummy),
ATTR_TYPE_END) != 1
#endif
)
msg_warn("%s: cannot send file descriptor: %m", myname);
if (close(fd) < 0)
msg_warn("close(%d): %m", fd);
scache_endp_hits++;
return;
}
}
/* scache_save_dest_service - protocol to save destination->endpoint binding */
static void scache_save_dest_service(VSTREAM *client_stream)
{
const char *myname = "scache_save_dest_service";
int ttl;
SCACHE_SIZE size;
if (attr_scan(client_stream,
ATTR_FLAG_STRICT,
RECV_ATTR_INT(MAIL_ATTR_TTL, &ttl),
RECV_ATTR_STR(MAIL_ATTR_LABEL, scache_dest_label),
RECV_ATTR_STR(MAIL_ATTR_PROP, scache_dest_prop),
RECV_ATTR_STR(MAIL_ATTR_LABEL, scache_endp_label),
ATTR_TYPE_END) != 4
|| ttl <= 0) {
msg_warn("%s: bad or missing request parameter", myname);
attr_print(client_stream, ATTR_FLAG_NONE,
SEND_ATTR_INT(MAIL_ATTR_STATUS, SCACHE_STAT_BAD),
ATTR_TYPE_END);
return;
} else {
scache_save_dest(scache,
ttl > var_scache_ttl_lim ? var_scache_ttl_lim : ttl,
STR(scache_dest_label), STR(scache_dest_prop),
STR(scache_endp_label));
attr_print(client_stream, ATTR_FLAG_NONE,
SEND_ATTR_INT(MAIL_ATTR_STATUS, SCACHE_STAT_OK),
ATTR_TYPE_END);
scache_size(scache, &size);
if (size.dest_count > scache_dest_count)
scache_dest_count = size.dest_count;
if (size.endp_count > scache_endp_count)
scache_endp_count = size.endp_count;
return;
}
}
/* scache_find_dest_service - protocol to find connection for destination */
static void scache_find_dest_service(VSTREAM *client_stream)
{
const char *myname = "scache_find_dest_service";
int fd;
if (attr_scan(client_stream,
ATTR_FLAG_STRICT,
RECV_ATTR_STR(MAIL_ATTR_LABEL, scache_dest_label),
ATTR_TYPE_END) != 1) {
msg_warn("%s: bad or missing request parameter", myname);
attr_print(client_stream, ATTR_FLAG_NONE,
SEND_ATTR_INT(MAIL_ATTR_STATUS, SCACHE_STAT_BAD),
SEND_ATTR_STR(MAIL_ATTR_PROP, ""),
SEND_ATTR_STR(MAIL_ATTR_PROP, ""),
ATTR_TYPE_END);
return;
} else if ((fd = scache_find_dest(scache, STR(scache_dest_label),
scache_dest_prop,
scache_endp_prop)) < 0) {
attr_print(client_stream, ATTR_FLAG_NONE,
SEND_ATTR_INT(MAIL_ATTR_STATUS, SCACHE_STAT_FAIL),
SEND_ATTR_STR(MAIL_ATTR_PROP, ""),
SEND_ATTR_STR(MAIL_ATTR_PROP, ""),
ATTR_TYPE_END);
scache_dest_miss++;
return;
} else {
attr_print(client_stream, ATTR_FLAG_NONE,
SEND_ATTR_INT(MAIL_ATTR_STATUS, SCACHE_STAT_OK),
SEND_ATTR_STR(MAIL_ATTR_PROP, STR(scache_dest_prop)),
SEND_ATTR_STR(MAIL_ATTR_PROP, STR(scache_endp_prop)),
ATTR_TYPE_END);
if (vstream_fflush(client_stream) != 0
#ifdef CANT_WRITE_BEFORE_SENDING_FD
|| attr_scan(client_stream, ATTR_FLAG_STRICT,
RECV_ATTR_STR(MAIL_ATTR_DUMMY, scache_dummy),
ATTR_TYPE_END) != 1
#endif
|| LOCAL_SEND_FD(vstream_fileno(client_stream), fd) < 0
#ifdef MUST_READ_AFTER_SENDING_FD
|| attr_scan(client_stream, ATTR_FLAG_STRICT,
RECV_ATTR_STR(MAIL_ATTR_DUMMY, scache_dummy),
ATTR_TYPE_END) != 1
#endif
)
msg_warn("%s: cannot send file descriptor: %m", myname);
if (close(fd) < 0)
msg_warn("close(%d): %m", fd);
scache_dest_hits++;
return;
}
}
/* scache_service - perform service for client */
static void scache_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]);
/*
* This routine runs whenever a client connects to the UNIX-domain socket
* dedicated to the scache service. All connection-management stuff is
* handled by the common code in multi_server.c.
*
* XXX Workaround: with some requests, the client sends a dummy message
* after the server replies (yes that's a botch). When the scache server
* is slow, this dummy message may become concatenated with the next
* request from the same client. The do-while loop below will repeat
* instead of discarding the client request. We must process it now
* because there will be no select() notification.
*/
do {
if (attr_scan(client_stream,
ATTR_FLAG_MORE | ATTR_FLAG_STRICT,
RECV_ATTR_STR(MAIL_ATTR_REQ, scache_request),
ATTR_TYPE_END) == 1) {
if (VSTREQ(scache_request, SCACHE_REQ_SAVE_DEST)) {
scache_save_dest_service(client_stream);
} else if (VSTREQ(scache_request, SCACHE_REQ_FIND_DEST)) {
scache_find_dest_service(client_stream);
} else if (VSTREQ(scache_request, SCACHE_REQ_SAVE_ENDP)) {
scache_save_endp_service(client_stream);
} else if (VSTREQ(scache_request, SCACHE_REQ_FIND_ENDP)) {
scache_find_endp_service(client_stream);
} else {
msg_warn("unrecognized request: \"%s\", ignored",
STR(scache_request));
attr_print(client_stream, ATTR_FLAG_NONE,
SEND_ATTR_INT(MAIL_ATTR_STATUS, SCACHE_STAT_BAD),
ATTR_TYPE_END);
}
}
} while (vstream_peek(client_stream) > 0);
vstream_fflush(client_stream);
}
/* scache_status_dump - log and reset cache statistics */
static void scache_status_dump(char *unused_name, char **unused_argv)
{
if (scache_dest_hits || scache_dest_miss
|| scache_endp_hits || scache_endp_miss
|| scache_dest_count || scache_endp_count
|| scache_sess_count)
msg_info("statistics: start interval %.15s",
ctime(&scache_start_time) + 4);
if (scache_dest_hits || scache_dest_miss) {
msg_info("statistics: domain lookup hits=%d miss=%d success=%d%%",
scache_dest_hits, scache_dest_miss,
scache_dest_hits * 100
/ (scache_dest_hits + scache_dest_miss));
scache_dest_hits = scache_dest_miss = 0;
}
if (scache_endp_hits || scache_endp_miss) {
msg_info("statistics: address lookup hits=%d miss=%d success=%d%%",
scache_endp_hits, scache_endp_miss,
scache_endp_hits * 100
/ (scache_endp_hits + scache_endp_miss));
scache_endp_hits = scache_endp_miss = 0;
}
if (scache_dest_count || scache_endp_count || scache_sess_count) {
msg_info("statistics: max simultaneous domains=%d addresses=%d connection=%d",
scache_dest_count, scache_endp_count, scache_sess_count);
scache_dest_count = 0;
scache_endp_count = 0;
scache_sess_count = 0;
}
scache_start_time = event_time();
}
/* scache_status_update - log and reset cache statistics periodically */
static void scache_status_update(int unused_event, void *context)
{
scache_status_dump((char *) 0, (char **) 0);
event_request_timer(scache_status_update, context, var_scache_stat_time);
}
/* post_jail_init - initialization after privilege drop */
static void post_jail_init(char *unused_name, char **unused_argv)
{
/*
* Pre-allocate the cache instance.
*/
scache = scache_multi_create();
/*
* Pre-allocate buffers.
*/
scache_request = vstring_alloc(10);
scache_dest_label = vstring_alloc(10);
scache_dest_prop = vstring_alloc(10);
scache_endp_label = vstring_alloc(10);
scache_endp_prop = vstring_alloc(10);
#ifdef CANT_WRITE_BEFORE_SENDING_FD
scache_dummy = vstring_alloc(10);
#endif
/*
* Disable the max_use limit. We still terminate when no client is
* connected for $idle_limit time units.
*/
var_use_limit = 0;
/*
* Dump and reset cache statistics every so often.
*/
event_request_timer(scache_status_update, (void *) 0, var_scache_stat_time);
scache_start_time = event_time();
}
/* scache_post_accept - announce our protocol */
static void scache_post_accept(VSTREAM *stream, char *unused_name,
char **unused_argv, HTABLE *unused_table)
{
/*
* Announce the protocol.
*/
attr_print(stream, ATTR_FLAG_NONE,
SEND_ATTR_STR(MAIL_ATTR_PROTO, MAIL_ATTR_PROTO_SCACHE),
ATTR_TYPE_END);
(void) vstream_fflush(stream);
}
MAIL_VERSION_STAMP_DECLARE;
/* main - pass control to the multi-threaded skeleton */
int main(int argc, char **argv)
{
static const CONFIG_TIME_TABLE time_table[] = {
VAR_SCACHE_TTL_LIM, DEF_SCACHE_TTL_LIM, &var_scache_ttl_lim, 1, 0,
VAR_SCACHE_STAT_TIME, DEF_SCACHE_STAT_TIME, &var_scache_stat_time, 1, 0,
0,
};
/*
* Fingerprint executables and core dumps.
*/
MAIL_VERSION_STAMP_ALLOCATE;
multi_server_main(argc, argv, scache_service,
CA_MAIL_SERVER_TIME_TABLE(time_table),
CA_MAIL_SERVER_POST_INIT(post_jail_init),
CA_MAIL_SERVER_POST_ACCEPT(scache_post_accept),
CA_MAIL_SERVER_EXIT(scache_status_dump),
CA_MAIL_SERVER_SOLITARY,
0);
}