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-rw-r--r--agent/cache.c314
1 files changed, 314 insertions, 0 deletions
diff --git a/agent/cache.c b/agent/cache.c
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+++ b/agent/cache.c
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+/* cache.c - keep a cache of passphrases
+ * Copyright (C) 2002 Free Software Foundation, Inc.
+ *
+ * This file is part of GnuPG.
+ *
+ * GnuPG is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * GnuPG is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
+ */
+
+#include <config.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+#include <assert.h>
+
+#include "agent.h"
+
+struct secret_data_s {
+ int totallen; /* this includes the padding */
+ int datalen; /* actual data length */
+ char data[1];
+};
+
+typedef struct cache_item_s *ITEM;
+struct cache_item_s {
+ ITEM next;
+ time_t created;
+ time_t accessed;
+ int ttl; /* max. lifetime given in seonds */
+ int lockcount;
+ struct secret_data_s *pw;
+ char key[1];
+};
+
+
+static ITEM thecache;
+
+
+static void
+release_data (struct secret_data_s *data)
+{
+ xfree (data);
+}
+
+static struct secret_data_s *
+new_data (const void *data, size_t length)
+{
+ struct secret_data_s *d;
+ int total;
+
+ /* we pad the data to 32 bytes so that it get more complicated
+ finding something out by watching allocation patterns. This is
+ usally not possible but we better assume nothing about our
+ secure storage provider*/
+ total = length + 32 - (length % 32);
+
+ d = gcry_malloc_secure (sizeof *d + total - 1);
+ if (d)
+ {
+ d->totallen = total;
+ d->datalen = length;
+ memcpy (d->data, data, length);
+ }
+ return d;
+}
+
+
+/* check whether there are items to expire */
+static void
+housekeeping (void)
+{
+ ITEM r, rprev;
+ time_t current = gnupg_get_time ();
+
+ /* first expire the actual data */
+ for (r=thecache; r; r = r->next)
+ {
+ if (!r->lockcount && r->pw && r->accessed + r->ttl < current)
+ {
+ if (DBG_CACHE)
+ log_debug (" expired `%s' (%ds after last access)\n",
+ r->key, r->ttl);
+ release_data (r->pw);
+ r->pw = NULL;
+ r->accessed = current;
+ }
+ }
+
+ /* second, make sure that we also remove them based on the created stamp so
+ that the user has to enter it from time to time. We do this every hour */
+ for (r=thecache; r; r = r->next)
+ {
+ if (!r->lockcount && r->pw && r->created + 60*60 < current)
+ {
+ if (DBG_CACHE)
+ log_debug (" expired `%s' (1h after creation)\n", r->key);
+ release_data (r->pw);
+ r->pw = NULL;
+ r->accessed = current;
+ }
+ }
+
+ /* third, make sure that we don't have too many items in the list.
+ Expire old and unused entries after 30 minutes */
+ for (rprev=NULL, r=thecache; r; )
+ {
+ if (!r->pw && r->accessed + 60*30 < current)
+ {
+ if (r->lockcount)
+ {
+ log_error ("can't remove unused cache entry `%s' due to"
+ " lockcount=%d\n",
+ r->key, r->lockcount);
+ r->accessed += 60*10; /* next error message in 10 minutes */
+ rprev = r;
+ r = r->next;
+ }
+ else
+ {
+ ITEM r2 = r->next;
+ if (DBG_CACHE)
+ log_debug (" removed `%s' (slot not used for 30m)\n", r->key);
+ xfree (r);
+ if (!rprev)
+ thecache = r2;
+ else
+ rprev->next = r2;
+ r = r2;
+ }
+ }
+ else
+ {
+ rprev = r;
+ r = r->next;
+ }
+ }
+}
+
+
+void
+agent_flush_cache (void)
+{
+ ITEM r;
+
+ if (DBG_CACHE)
+ log_debug ("agent_flush_cache\n");
+
+ for (r=thecache; r; r = r->next)
+ {
+ if (!r->lockcount && r->pw)
+ {
+ if (DBG_CACHE)
+ log_debug (" flushing `%s'\n", r->key);
+ release_data (r->pw);
+ r->pw = NULL;
+ r->accessed = 0;
+ }
+ else if (r->lockcount && r->pw)
+ {
+ if (DBG_CACHE)
+ log_debug (" marked `%s' for flushing\n", r->key);
+ r->accessed = 0;
+ r->ttl = 0;
+ }
+ }
+}
+
+
+
+/* Store DATA of length DATALEN in the cache under KEY and mark it
+ with a maximum lifetime of TTL seconds. If there is already data
+ under this key, it will be replaced. Using a DATA of NULL deletes
+ the entry */
+int
+agent_put_cache (const char *key, const char *data, int ttl)
+{
+ ITEM r;
+
+ if (DBG_CACHE)
+ log_debug ("agent_put_cache `%s'\n", key);
+ housekeeping ();
+
+ if (ttl < 1)
+ ttl = opt.def_cache_ttl;
+ if (!ttl)
+ return 0;
+
+ for (r=thecache; r; r = r->next)
+ {
+ if (!r->lockcount && !strcmp (r->key, key))
+ break;
+ }
+ if (r)
+ { /* replace */
+ if (r->pw)
+ {
+ release_data (r->pw);
+ r->pw = NULL;
+ }
+ if (data)
+ {
+ r->created = r->accessed = gnupg_get_time ();
+ r->ttl = ttl;
+ r->pw = new_data (data, strlen (data)+1);
+ if (!r->pw)
+ log_error ("out of core while allocating new cache item\n");
+ }
+ }
+ else if (data)
+ { /* simply insert */
+ r = xtrycalloc (1, sizeof *r + strlen (key));
+ if (!r)
+ log_error ("out of core while allocating new cache control\n");
+ else
+ {
+ strcpy (r->key, key);
+ r->created = r->accessed = gnupg_get_time ();
+ r->ttl = ttl;
+ r->pw = new_data (data, strlen (data)+1);
+ if (!r->pw)
+ {
+ log_error ("out of core while allocating new cache item\n");
+ xfree (r);
+ }
+ else
+ {
+ r->next = thecache;
+ thecache = r;
+ }
+ }
+ }
+ return 0;
+}
+
+
+/* Try to find an item in the cache */
+const char *
+agent_get_cache (const char *key, void **cache_id)
+{
+ ITEM r;
+
+ if (DBG_CACHE)
+ log_debug ("agent_get_cache `%s'...\n", key);
+ housekeeping ();
+
+ /* first try to find one with no locks - this is an updated cache
+ entry: We might have entries with a lockcount and without a
+ lockcount. */
+ for (r=thecache; r; r = r->next)
+ {
+ if (!r->lockcount && r->pw && !strcmp (r->key, key))
+ {
+ /* put_cache does only put strings into the cache, so we
+ don't need the lengths */
+ r->accessed = gnupg_get_time ();
+ if (DBG_CACHE)
+ log_debug ("... hit\n");
+ r->lockcount++;
+ *cache_id = r;
+ return r->pw->data;
+ }
+ }
+ /* again, but this time get even one with a lockcount set */
+ for (r=thecache; r; r = r->next)
+ {
+ if (r->pw && !strcmp (r->key, key))
+ {
+ r->accessed = gnupg_get_time ();
+ if (DBG_CACHE)
+ log_debug ("... hit (locked)\n");
+ r->lockcount++;
+ *cache_id = r;
+ return r->pw->data;
+ }
+ }
+ if (DBG_CACHE)
+ log_debug ("... miss\n");
+
+ *cache_id = NULL;
+ return NULL;
+}
+
+
+void
+agent_unlock_cache_entry (void **cache_id)
+{
+ ITEM r;
+
+ for (r=thecache; r; r = r->next)
+ {
+ if (r == *cache_id)
+ {
+ if (!r->lockcount)
+ log_error ("trying to unlock non-locked cache entry `%s'\n",
+ r->key);
+ else
+ r->lockcount--;
+ return;
+ }
+ }
+}
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