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/* -*- mode: c; c-basic-offset: 4; indent-tabs-mode: nil -*- */
/* kdc/replay.c - Replay lookaside cache for the KDC, to avoid extra work */
/*
* Copyright 1991 by the Massachusetts Institute of Technology.
* All Rights Reserved.
*
* Export of this software from the United States of America may
* require a specific license from the United States Government.
* It is the responsibility of any person or organization contemplating
* export to obtain such a license before exporting.
*
* WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
* distribute this software and its documentation for any purpose and
* without fee is hereby granted, provided that the above copyright
* notice appear in all copies and that both that copyright notice and
* this permission notice appear in supporting documentation, and that
* the name of M.I.T. not be used in advertising or publicity pertaining
* to distribution of the software without specific, written prior
* permission. Furthermore if you modify this software you must label
* your software as modified software and not distribute it in such a
* fashion that it might be confused with the original M.I.T. software.
* M.I.T. makes no representations about the suitability of
* this software for any purpose. It is provided "as is" without express
* or implied warranty.
*/
#include "k5-int.h"
#include "kdc_util.h"
#include "extern.h"
#ifndef NOCACHE
typedef struct _krb5_kdc_replay_ent {
struct _krb5_kdc_replay_ent *next;
int num_hits;
krb5_int32 timein;
time_t db_age;
krb5_data *req_packet;
krb5_data *reply_packet;
} krb5_kdc_replay_ent;
static krb5_kdc_replay_ent root_ptr = {0};
static int hits = 0;
static int calls = 0;
static int max_hits_per_entry = 0;
static int num_entries = 0;
#define STALE_TIME 2*60 /* two minutes */
#define STALE(ptr) ((abs((ptr)->timein - timenow) >= STALE_TIME) || \
((ptr)->db_age != db_age))
#define MATCH(ptr) (((ptr)->req_packet->length == inpkt->length) && \
!memcmp((ptr)->req_packet->data, inpkt->data, \
inpkt->length) && \
((ptr)->db_age == db_age))
/* XXX
Todo: quench the size of the queue...
*/
/* return TRUE if outpkt is filled in with a packet to reply with,
FALSE if the caller should do the work */
krb5_boolean
kdc_check_lookaside(krb5_data *inpkt, krb5_data **outpkt)
{
krb5_int32 timenow;
register krb5_kdc_replay_ent *eptr, *last, *hold;
time_t db_age;
if (krb5_timeofday(kdc_context, &timenow) ||
krb5_db_get_age(kdc_context, 0, &db_age))
return FALSE;
calls++;
/* search for a replay entry in the queue, possibly removing
stale entries while we're here */
if (root_ptr.next) {
for (last = &root_ptr, eptr = root_ptr.next;
eptr;
eptr = eptr->next) {
if (MATCH(eptr)) {
eptr->num_hits++;
hits++;
if (krb5_copy_data(kdc_context, eptr->reply_packet, outpkt))
return FALSE;
else
return TRUE;
/* return here, don't bother flushing even if it is stale.
if we just matched, we may get another retransmit... */
}
if (STALE(eptr)) {
/* flush it and collect stats */
max_hits_per_entry = max(max_hits_per_entry, eptr->num_hits);
krb5_free_data(kdc_context, eptr->req_packet);
krb5_free_data(kdc_context, eptr->reply_packet);
hold = eptr;
last->next = eptr->next;
eptr = last;
free(hold);
} else {
/* this isn't it, just move along */
last = eptr;
}
}
}
return FALSE;
}
/* insert a request & reply into the lookaside queue. assumes it's not
already there, and can fail softly due to other weird errors. */
void
kdc_insert_lookaside(krb5_data *inpkt, krb5_data *outpkt)
{
register krb5_kdc_replay_ent *eptr;
krb5_int32 timenow;
time_t db_age;
if (krb5_timeofday(kdc_context, &timenow) ||
krb5_db_get_age(kdc_context, 0, &db_age))
return;
/* this is a new entry */
eptr = (krb5_kdc_replay_ent *)calloc(1, sizeof(*eptr));
if (!eptr)
return;
eptr->timein = timenow;
eptr->db_age = db_age;
/*
* This is going to hurt a lot malloc()-wise due to the need to
* allocate memory for the krb5_data and krb5_address elements.
* ARGH!
*/
if (krb5_copy_data(kdc_context, inpkt, &eptr->req_packet)) {
free(eptr);
return;
}
if (krb5_copy_data(kdc_context, outpkt, &eptr->reply_packet)) {
krb5_free_data(kdc_context, eptr->req_packet);
free(eptr);
return;
}
eptr->next = root_ptr.next;
root_ptr.next = eptr;
num_entries++;
return;
}
/* frees memory associated with the lookaside queue for memory profiling */
void
kdc_free_lookaside(krb5_context kcontext)
{
register krb5_kdc_replay_ent *eptr, *last, *hold;
if (root_ptr.next) {
for (last = &root_ptr, eptr = root_ptr.next;
eptr; eptr = eptr->next) {
krb5_free_data(kcontext, eptr->req_packet);
krb5_free_data(kcontext, eptr->reply_packet);
hold = eptr;
last->next = eptr->next;
eptr = last;
free(hold);
}
}
}
#endif /* NOCACHE */
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