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/*
* uhub - A tiny ADC p2p connection hub
* Copyright (C) 2007-2009, Jan Vidar Krey
*
* This program 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 3 of the License, or
* (at your option) any later version.
*
* This program 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, see <http://www.gnu.org/licenses/>.
*
*/
#include "uhub.h"
const char* BASE32_ALPHABET = "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567";
char* sid_to_string(sid_t sid_)
{
static char t_sid[5];
sid_t sid = (sid_ & 0xFFFFF); /* 20 bits only */
sid_t A, B, C, D = 0;
D = (sid % 32);
sid = (sid - D) / 32;
C = (sid % 32);
sid = (sid - C) / 32;
B = (sid % 32);
sid = (sid - B) / 32;
A = (sid % 32);
t_sid[0] = BASE32_ALPHABET[A];
t_sid[1] = BASE32_ALPHABET[B];
t_sid[2] = BASE32_ALPHABET[C];
t_sid[3] = BASE32_ALPHABET[D];
t_sid[4] = 0;
return t_sid;
}
sid_t string_to_sid(const char* sid)
{
sid_t nsid = 0;
sid_t n, x;
sid_t factors[] = { 32768, 1024, 32, 1};
if (!sid || strlen(sid) != 4) return 0;
for (n = 0; n < 4; n++) {
for (x = 0; x < strlen(BASE32_ALPHABET); x++)
if (sid[n] == BASE32_ALPHABET[x]) break;
if (x == 32) return 0;
nsid += x * factors[n];
}
return nsid;
}
/*
* Session IDs are heavily reused, since they are a fairly scarce
* resource. Only one (2^10)-1 exist, since it is a four byte base32-encoded
* value and 'AAAA' (0) is reserved for the hub.
*
* Initialize with sid_initialize(), which sets min and max to one, and count to 0.
*
* When allocating a session ID:
* - If 'count' is less than the pool size (max-min), then allocate within the pool
* - Increase the pool size (see below)
* - If unable to do that, hub is really full - don't let anyone in!
*
* When freeing a session ID:
* - If the session ID being freed is 'max', then decrease the pool size by one.
*
*/
struct sid_pool
{
sid_t min;
sid_t max;
sid_t count;
struct hub_user** map;
};
struct sid_pool* sid_pool_create(sid_t max)
{
struct sid_pool* pool = hub_malloc(sizeof(struct sid_pool));
if (!pool)
return 0;
pool->min = 1;
pool->max = max + 1;
pool->count = 0;
pool->map = hub_malloc_zero(sizeof(struct hub_user*) * pool->max);
if (!pool->map)
{
hub_free(pool);
return 0;
}
pool->map[0] = (struct hub_user*) pool; /* hack to reserve the first sid. */
#ifdef DEBUG_SID
LOG_DUMP("SID_POOL: max=%d", (int) pool->max);
#endif
return pool;
}
void sid_pool_destroy(struct sid_pool* pool)
{
#ifdef DEBUG_SID
LOG_DUMP("SID_POOL: destroying, current allocs=%d", (int) pool->count);
#endif
hub_free(pool->map);
hub_free(pool);
}
sid_t sid_alloc(struct sid_pool* pool, struct hub_user* user)
{
if (pool->count >= (pool->max - pool->min))
{
#ifdef DEBUG_SID
LOG_DUMP("SID_POOL: alloc, sid pool is full.");
#endif
return 0;
}
sid_t n = (++pool->count);
for (; (pool->map[n % pool->max]); n++) ;
#ifdef DEBUG_SID
LOG_DUMP("SID_ALLOC: %d, user=%p", (int) n, user);
#endif
pool->map[n] = user;
return n;
}
void sid_free(struct sid_pool* pool, sid_t sid)
{
#ifdef DEBUG_SID
LOG_DUMP("SID_FREE: %d", (int) sid);
#endif
pool->map[sid] = 0;
pool->count--;
}
struct hub_user* sid_lookup(struct sid_pool* pool, sid_t sid)
{
if (!sid || (sid >= pool->max))
return 0;
return pool->map[sid];
}
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