release/src/router/ppp/pppd/plugins/pppoe/pppoehash.c

   1 /* PPPoE support library "libpppoe"
   2  *
   3  * Copyright 2000 Michal Ostrowski <mostrows@styx.uwaterloo.ca>,
   4  *                Jamal Hadi Salim <hadi@cyberus.ca>
   5  *
   6  *  This program is free software; you can redistribute it and/or
   7  *  modify it under the terms of the GNU General Public License
   8  *  as published by the Free Software Foundation; either version
   9  *  2 of the License, or (at your option) any later version.
  10  */
  11 #include <pppoe.h>
  12
  13
  14 #define PPPOE_HASH_SIZE 16
  15
  16
  17 static inline int keycmp(char *a, char *b, int x, int y){
  18     return x==y && !memcmp(a,b,x);
  19 }
  20
  21 static int hash_con(int key_len, char* key)
  22 {
  23     int i = 0;
  24     char hash[sizeof(int)]={0,};
  25
  26     for (i = 0; i < key_len ; ++i)
  27         hash[i% sizeof(int)] = hash[i%sizeof(int)] ^ key[i];
  28
  29     i = (*((int*)hash)) ;
  30     i &= PPPOE_HASH_SIZE - 1;
  31
  32     return i;
  33 }
  34
  35 static struct pppoe_con *con_ht[PPPOE_HASH_SIZE] = { 0, };
  36
  37 struct pppoe_con *get_con(int len, char *key)
  38 {
  39     int hash = hash_con(len, key);
  40     struct pppoe_con *ret;
  41
  42     ret = con_ht[hash];
  43
  44     while (ret && !keycmp(ret->key,key, ret->key_len, len))
  45         ret = ret->next;
  46
  47     return ret;
  48 }
  49
  50 int store_con(struct pppoe_con *pc)
  51 {
  52     int hash = hash_con(pc->key_len, pc->key);
  53     struct pppoe_con *ret;
  54
  55     ret = con_ht[hash];
  56     while (ret) {
  57         if (!keycmp(ret->key, pc->key, ret->key_len, pc->key_len))
  58             return -EALREADY;
  59
  60         ret = ret->next;
  61     }
  62
  63     if (!ret) {
  64         pc->next = con_ht[hash];
  65         con_ht[hash] = pc;
  66     }
  67
  68     return 0;
  69 }
  70
  71 struct pppoe_con *delete_con(unsigned long len, char *key)
  72 {
  73     int hash = hash_con(len, key);
  74     struct pppoe_con *ret, **src;
  75
  76     ret = con_ht[hash];
  77     src = &con_ht[hash];
  78
  79     while (ret) {
  80         if (keycmp(ret->key,key, ret->key_len, len)) {
  81             *src = ret->next;
  82             break;
  83         }
  84
  85         src = &ret->next;
  86         ret = ret->next;
  87     }
  88
  89     return ret;
  90 }
  91