dlls/netapi32/nbnamecache.c

   1 /* Copyright (c) 2003 Juan Lang
   2  *
   3  * This library is free software; you can redistribute it and/or
   4  * modify it under the terms of the GNU Lesser General Public
   5  * License as published by the Free Software Foundation; either
   6  * version 2.1 of the License, or (at your option) any later version.
   7  *
   8  * This library is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * Lesser General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU Lesser General Public
  14  * License along with this library; if not, write to the Free Software
  15  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  16  *
  17  * This implementation uses a linked list, because I don't have a decent
  18  * hash table implementation handy.  This is somewhat inefficient, but it's
  19  * rather more efficient than not having a name cache at all.
  20  */
  21
  22 #include "config.h"
  23 #include "wine/port.h"
  24 #include "wine/debug.h"
  25
  26 #include "nbnamecache.h"
  27
  28 WINE_DEFAULT_DEBUG_CHANNEL(netbios);
  29
  30 typedef struct _NBNameCacheNode
  31 {
  32     DWORD expireTime;
  33     NBNameCacheEntry *entry;
  34     struct _NBNameCacheNode *next;
  35 } NBNameCacheNode;
  36
  37 struct NBNameCache
  38 {
  39     HANDLE heap;
  40     CRITICAL_SECTION cs;
  41     DWORD entryExpireTimeMS;
  42     NBNameCacheNode *head;
  43 };
  44
  45 /* Unlinks the node pointed to by *prev, and frees any associated memory.
  46  * If that node's next pointed to another node, *prev now points to it.
  47  * Assumes the caller owns cache's lock.
  48  */
  49 static void NBNameCacheUnlinkNode(struct NBNameCache *cache,
  50  NBNameCacheNode **prev)
  51 {
  52     if (cache && prev && *prev)
  53     {
  54         NBNameCacheNode *next = (*prev)->next;
  55
  56         HeapFree(cache->heap, 0, (*prev)->entry);
  57         HeapFree(cache->heap, 0, *prev);
  58         *prev = next;
  59     }
  60 }
  61
  62 /* Walks the list beginning with cache->head looking for the node with name
  63  * name.  If the node is found, returns a pointer to the next pointer of the
  64  * node _prior_ to the found node (or head if head points to it).  Thus, if the
  65  * node's all you want, dereference the return value twice.  If you want to
  66  * modify the list, modify the referent of the return value.
  67  * While it's at it, deletes nodes whose time has expired (except the node
  68  * you're looking for, of course).
  69  * Returns NULL if the node isn't found.
  70  * Assumes the caller owns cache's lock.
  71  */
  72 static NBNameCacheNode **NBNameCacheWalk(struct NBNameCache *cache,
  73  const char name[NCBNAMSZ])
  74 {
  75     NBNameCacheNode **ret = NULL;
  76
  77     if (cache && cache->head)
  78     {
  79         NBNameCacheNode **ptr;
  80
  81         ptr = &cache->head;
  82         while (ptr && *ptr && (*ptr)->entry)
  83         {
  84             if (!memcmp((*ptr)->entry->name, name, NCBNAMSZ - 1))
  85                 ret = ptr;
  86             else
  87             {
  88                 if (GetTickCount() > (*ptr)->expireTime)
  89                     NBNameCacheUnlinkNode(cache, ptr);
  90             }
  91             if (*ptr)
  92                 ptr = &(*ptr)->next;
  93         }
  94     }
  95     return ret;
  96 }
  97
  98 struct NBNameCache *NBNameCacheCreate(HANDLE heap, DWORD entryExpireTimeMS)
  99 {
 100     struct NBNameCache *cache;
 101
 102
 103     if (!heap)
 104         heap = GetProcessHeap();
 105     cache = HeapAlloc(heap, 0, sizeof(struct NBNameCache));
 106     if (cache)
 107     {
 108         cache->heap = heap;
 109         InitializeCriticalSection(&cache->cs);
 110         cache->entryExpireTimeMS = entryExpireTimeMS;
 111         cache->head = NULL;
 112     }
 113     return cache;
 114 }
 115
 116 BOOL NBNameCacheAddEntry(struct NBNameCache *cache, NBNameCacheEntry *entry)
 117 {
 118     BOOL ret;
 119
 120     if (cache && entry)
 121     {
 122         NBNameCacheNode **node;
 123
 124         EnterCriticalSection(&cache->cs);
 125         node = NBNameCacheWalk(cache, entry->name);
 126         if (node)
 127         {
 128             (*node)->expireTime = GetTickCount() +
 129              cache->entryExpireTimeMS;
 130             HeapFree(cache->heap, 0, (*node)->entry);
 131             (*node)->entry = entry;
 132             ret = TRUE;
 133         }
 134         else
 135         {
 136             NBNameCacheNode *newNode = HeapAlloc(cache->heap, 0, sizeof(NBNameCacheNode));
 137             if (newNode)
 138             {
 139                 newNode->expireTime = GetTickCount() +
 140                  cache->entryExpireTimeMS;
 141                 newNode->entry = entry;
 142                 newNode->next = cache->head;
 143                 cache->head = newNode;
 144                 ret = TRUE;
 145             }
 146             else
 147                 ret = FALSE;
 148         }
 149         LeaveCriticalSection(&cache->cs);
 150     }
 151     else
 152         ret = FALSE;
 153     return ret;
 154 }
 155
 156 const NBNameCacheEntry *NBNameCacheFindEntry(struct NBNameCache *cache,
 157  const UCHAR name[NCBNAMSZ])
 158 {
 159     const NBNameCacheEntry *ret;
 160     UCHAR printName[NCBNAMSZ];
 161
 162     memcpy(printName, name, NCBNAMSZ - 1);
 163     printName[NCBNAMSZ - 1] = '\0';
 164     if (cache)
 165     {
 166         NBNameCacheNode **node;
 167
 168         EnterCriticalSection(&cache->cs);
 169         node = NBNameCacheWalk(cache, name);
 170         if (node)
 171             ret = (*node)->entry;
 172         else
 173             ret = NULL;
 174         LeaveCriticalSection(&cache->cs);
 175     }
 176     else
 177         ret = NULL;
 178     return ret;
 179 }
 180
 181 BOOL NBNameCacheUpdateNBName(struct NBNameCache *cache,
 182  const UCHAR name[NCBNAMSZ], const UCHAR nbname[NCBNAMSZ])
 183 {
 184     BOOL ret;
 185
 186     if (cache)
 187     {
 188         NBNameCacheNode **node;
 189
 190         EnterCriticalSection(&cache->cs);
 191         node = NBNameCacheWalk(cache, name);
 192         if (node && *node && (*node)->entry)
 193         {
 194             memcpy((*node)->entry->nbname, nbname, NCBNAMSZ);
 195             ret = TRUE;
 196         }
 197         else
 198             ret = FALSE;
 199         LeaveCriticalSection(&cache->cs);
 200     }
 201     else
 202         ret = FALSE;
 203     return ret;
 204 }
 205
 206 void NBNameCacheDestroy(struct NBNameCache *cache)
 207 {
 208     if (cache)
 209     {
 210         DeleteCriticalSection(&cache->cs);
 211         while (cache->head)
 212             NBNameCacheUnlinkNode(cache, &cache->head);
 213         HeapFree(cache->heap, 0, cache);
 214     }
 215 }