/**
 * @file BSecurity.c
 * @author Ambroz Bizjak <ambrop7@gmail.com>
 * 
 * @section LICENSE
 * 
 * This file is part of BadVPN.
 * 
 * BadVPN is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2
 * as published by the Free Software Foundation.
 * 
 * BadVPN 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.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#include <stddef.h>

#ifdef BADVPN_THREADWORK_USE_PTHREAD
    #include <pthread.h>
#endif

#include <openssl/crypto.h>

#include <misc/debug.h>
#include <misc/balloc.h>

#include <security/BSecurity.h>

int bsecurity_initialized = 0;

#ifdef BADVPN_THREADWORK_USE_PTHREAD
pthread_mutex_t *bsecurity_locks;
int bsecurity_num_locks;
#endif

#ifdef BADVPN_THREADWORK_USE_PTHREAD

static unsigned long id_callback (void)
{
    ASSERT(bsecurity_initialized)
    
    return (unsigned long)pthread_self();
}

static void locking_callback (int mode, int type, const char *file, int line)
{
    ASSERT(bsecurity_initialized)
    ASSERT(type >= 0)
    ASSERT(type < bsecurity_num_locks)
    
    if ((mode & CRYPTO_LOCK)) {
        ASSERT_FORCE(pthread_mutex_lock(&bsecurity_locks[type]) == 0)
    } else {
        ASSERT_FORCE(pthread_mutex_unlock(&bsecurity_locks[type]) == 0)
    }
}

#endif

int BSecurity_GlobalInitThreadSafe (void)
{
    ASSERT(!bsecurity_initialized)
    
    #ifdef BADVPN_THREADWORK_USE_PTHREAD
    
    // get number of locks
    int num_locks = CRYPTO_num_locks();
    ASSERT_FORCE(num_locks >= 0)
    
    // alloc locks array
    if (!(bsecurity_locks = BAllocArray(num_locks, sizeof(bsecurity_locks[0])))) {
        goto fail0;
    }
    
    // init locks
    bsecurity_num_locks = 0;
    for (int i = 0; i < num_locks; i++) {
        if (pthread_mutex_init(&bsecurity_locks[i], NULL) != 0) {
            goto fail1;
        }
        bsecurity_num_locks++;
    }
    
    #endif
    
    bsecurity_initialized = 1;
    
    #ifdef BADVPN_THREADWORK_USE_PTHREAD
    CRYPTO_set_id_callback(id_callback);
    CRYPTO_set_locking_callback(locking_callback);
    #endif
    
    return 1;
    
    #ifdef BADVPN_THREADWORK_USE_PTHREAD
fail1:
    while (bsecurity_num_locks > 0) {
        ASSERT_FORCE(pthread_mutex_destroy(&bsecurity_locks[bsecurity_num_locks - 1]) == 0)
        bsecurity_num_locks--;
    }
    BFree(bsecurity_locks);
fail0:
    return 0;
    #endif
}

void BSecurity_GlobalFreeThreadSafe (void)
{
    ASSERT(bsecurity_initialized)
    
    #ifdef BADVPN_THREADWORK_USE_PTHREAD
    
    // remove callbacks
    CRYPTO_set_locking_callback(NULL);
    CRYPTO_set_id_callback(NULL);
    
    // free locks
    while (bsecurity_num_locks > 0) {
        ASSERT_FORCE(pthread_mutex_destroy(&bsecurity_locks[bsecurity_num_locks - 1]) == 0)
        bsecurity_num_locks--;
    }
    
    // free locks array
    BFree(bsecurity_locks);
    
    #endif
    
    bsecurity_initialized = 0;
}

void BSecurity_GlobalAssertThreadSafe (int thread_safe)
{
    ASSERT(thread_safe == 0 || thread_safe == 1)
    ASSERT(!(thread_safe) || bsecurity_initialized)
}