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#ifndef _SCACHE_H_INCLUDED_
#define _SCACHE_H_INCLUDED_
/*++
/* NAME
/* scache 3h
/* SUMMARY
/* generic session cache API
/* SYNOPSIS
/* #include <scache.h>
/* DESCRIPTION
/* .nf
/*
* Utility library.
*/
#include <vstring.h>
typedef struct SCACHE SCACHE;
typedef struct SCACHE_SIZE SCACHE_SIZE;
/*
* In order to cache a session, we specify:
*
* - TTL for this session.
*
* - File descriptor.
*
* - Transport name and physical endpoint. The transport name must be included,
* because fall-back destinations can be transport-dependent, and routing
* for a given destination may be context dependent.
*
* In the case of SMTP, the physical endpoint is the numerical IP address and
* TCP port.
*
* - Application-specific endpoint properties.
*
* In the case of SMTP, the properties specify the ESMTP features advertised by
* the server.
*
* Note: with message delivery transports that have only one endpoint per
* logical destination, the above is the only information that needs to be
* maintained in a connection cache.
*/
typedef void (*SCACHE_SAVE_ENDP_FN) (SCACHE *, int, const char *, const char *, int);
typedef int (*SCACHE_FIND_ENDP_FN) (SCACHE *, const char *, VSTRING *);
/*
* The following information is stored in order to make a binding from
* logical destination to physical destination. One logical destination can
* have multiple physical destinations (and one physical destination can
* have multiple sessions).
*
* - TTL for this binding.
*
* - Transport name and logical destination.
*
* In the case of SMTP: the next-hop (NOT: fall-back) destination domain and
* destination network port. It is not useful to create a link for an
* address literal (but it is not harmful either: it just wastes a few
* bits). This information specifies the destination domain in [] if no MX
* lookup is done.
*
* - Application-specific properties.
*
* In case the of SMTP, the properties specify a) whether a physical endpoint
* is best mx host with respect to a logical or fall-back destination (this
* information is needed by the loop detection code in smtp_proto.c).
*
* - Transport name and physical endpoint (see above).
*
* Note 1: there is no need to store the binding's MX preference or equivalent
* with respect to the logical destination; a client should store only the
* first successful session for a given delivery request (otherwise the
* client would keep talking to a less preferred server after the cached
* connection for a more preferred server expires). After a failed delivery,
* the client should not attempt to cache follow-up sessions with less
* preferred endpoints under the same logical destination.
*
* Note 2: logical to physical bindings exist independently from cached
* sessions. The two types of information have independent TTLs; creation
* and destruction proceed independently. Thus, a logical to physical
* binding can refer to an endpoint for which all cached connections are
* occupied or expired.
*/
typedef void (*SCACHE_SAVE_DEST_FN) (SCACHE *, int, const char *, const char *, const char *);
typedef int (*SCACHE_FIND_DEST_FN) (SCACHE *, const char *, VSTRING *, VSTRING *);
/*
* Session cache statistics. These are the actual numbers at a specific
* point in time.
*/
struct SCACHE_SIZE {
int dest_count; /* Nr of destination names */
int endp_count; /* Nr of endpoint addresses */
int sess_count; /* Nr of cached sessions */
};
/*
* Generic session cache object. Actual session cache objects are derived
* types with some additional, cache dependent, private information.
*/
struct SCACHE {
SCACHE_SAVE_ENDP_FN save_endp;
SCACHE_FIND_ENDP_FN find_endp;
SCACHE_SAVE_DEST_FN save_dest;
SCACHE_FIND_DEST_FN find_dest;
void (*size) (struct SCACHE *, SCACHE_SIZE *);
void (*free) (struct SCACHE *);
};
extern SCACHE *scache_single_create(void);
extern SCACHE *scache_clnt_create(const char *, int, int, int);
extern SCACHE *scache_multi_create(void);
#define scache_save_endp(scache, ttl, endp_label, endp_prop, fd) \
(scache)->save_endp((scache), (ttl), (endp_label), (endp_prop), (fd))
#define scache_find_endp(scache, endp_label, endp_prop) \
(scache)->find_endp((scache), (endp_label), (endp_prop))
#define scache_save_dest(scache, ttl, dest_label, dest_prop, endp_label) \
(scache)->save_dest((scache), (ttl), (dest_label), (dest_prop), (endp_label))
#define scache_find_dest(scache, dest_label, dest_prop, endp_prop) \
(scache)->find_dest((scache), (dest_label), (dest_prop), (endp_prop))
#define scache_size(scache, stats) (scache)->size((scache), (stats))
#define scache_free(scache) (scache)->free(scache)
/*
* Cache types.
*/
#define SCACHE_TYPE_SINGLE 1 /* single-instance cache */
#define SCACHE_TYPE_CLIENT 2 /* session cache client */
#define SCACHE_TYPE_MULTI 3 /* multi-instance cache */
/*
* Client-server protocol.
*/
#define SCACHE_REQ_FIND_ENDP "find_endp"
#define SCACHE_REQ_SAVE_ENDP "save_endp"
#define SCACHE_REQ_FIND_DEST "find_dest"
#define SCACHE_REQ_SAVE_DEST "save_dest"
/*
* Session cache server status codes.
*/
#define SCACHE_STAT_OK 0 /* request completed successfully */
#define SCACHE_STAT_BAD 1 /* malformed request */
#define SCACHE_STAT_FAIL 2 /* request completed unsuccessfully */
/* LICENSE
/* .ad
/* .fi
/* The Secure Mailer license must be distributed with this software.
/* 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
/*--*/
#endif
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