/* ====================================================================
 * Copyright (c) 1998-2001 Ralf S. Engelschall. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following
 *    disclaimer in the documentation and/or other materials
 *    provided with the distribution.
 *
 * 3. All advertising materials mentioning features or use of this
 *    software must display the following acknowledgment:
 *    "This product includes software developed by
 *     Ralf S. Engelschall <rse@engelschall.com> for use in the
 *     mod_ssl project (http://www.modssl.org/)."
 *
 * 4. The names "mod_ssl" must not be used to endorse or promote
 *    products derived from this software without prior written
 *    permission. For written permission, please contact
 *    rse@engelschall.com.
 *
 * 5. Products derived from this software may not be called "mod_ssl"
 *    nor may "mod_ssl" appear in their names without prior
 *    written permission of Ralf S. Engelschall.
 *
 * THIS SOFTWARE IS PROVIDED BY RALF S. ENGELSCHALL ``AS IS'' AND ANY
 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL RALF S. ENGELSCHALL OR
 * HIS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * ==================================================================== */


#include <gdbm/ndbm.h>
#include <errno.h>

#include "lock.h"
#include "config.h"

char *sess_file;


void ssl_scache_dbm_expire(void)
{
  DBM *dbm;
  datum dbmkey;
  datum dbmval;
  time_t tExpiresAt;
  int nElements = 0;
  int nDeleted = 0;
  int bDelete;
  datum *keylist;
  int keyidx;
  int i;
  static time_t tLast = 0;
  time_t tNow;
  
  /*
  ** make sure the expiration for still not-accessed session
  ** cache entries is done only from time to time
  **/
  
  tNow = time(NULL);
  if (tNow < tLast + SSL_SESSION_CACHE_TIMEOUT)
    return;
  
  tLast = tNow;
  
  /*
  ** Here we have to be very carefully: Not all DBM libraries are
  ** smart enough to allow one to iterate over the elements and at the
  ** same time delete expired ones. Some of them get totally crazy
  ** while others have no problems. So we have to do it the slower but
  ** more safe way: we first iterate over all elements and remember
  ** those which have to be expired. Then in a second pass we delete
  ** all those expired elements. Additionally we reopen the DBM file
  ** to be really safe in state.
  */

#define KEYMAX 1024
  ssl_mutex_on();
  for (;;) {
    /*
    ** allocate memory for the key array
    **
    ** NOTE:- here i am not worried if i am running low on memory it does not cause the system to fail so i shall try in my next attempt
    ** :-) go happy next time better luck :-)
    */
    
    if ((keylist = (datum *) malloc(sizeof(dbmkey)*KEYMAX)) == NULL)
      {
	break;
      }

    /* pass 1: scan DBM database */
    keyidx = 0;
    if ((dbm = dbm_open(sess_file, O_RDWR, SSL_DBM_FILE_MODE)) == NULL)
      {
	(void) fprintf(stderr,"Cannot open SSLSessionCache DBM file `%s' for scanning",sess_file);
	break;
      }
    
    dbmkey = dbm_firstkey(dbm);
    
    while (dbmkey.dptr != NULL)
      {
	nElements++;
	bDelete = 0;
	dbmval = dbm_fetch(dbm, dbmkey);
	
	if(dbmval.dsize <= sizeof(time_t) || dbmval.dptr == NULL)
	  bDelete = 1;
	else
	  {
	    memcpy(&tExpiresAt, dbmval.dptr, sizeof(time_t));
	    if(tExpiresAt <= tNow)
	      bDelete = 1;
	  }
	
	if (bDelete)
	  {
	    if ((keylist[keyidx].dptr = (char *) malloc(dbmkey.dsize)) != NULL)
	      {
		memcpy(keylist[keyidx].dptr, dbmkey.dptr, dbmkey.dsize);
		keylist[keyidx].dsize = dbmkey.dsize;
		keyidx++;
		
		if(keyidx == KEYMAX)
		  break;
	      }
	  }
	
	dbmkey = dbm_nextkey(dbm);
      }

    dbm_close(dbm);
    
    /* pass 2: delete expired elements */
    if ((dbm = dbm_open(sess_file, O_RDWR, SSL_DBM_FILE_MODE)) == NULL)
      {
	(void) fprintf(stderr, "Cannot re-open SSLSessionCache DBM file `%s' for expiring",sess_file);
	break;
      }
    
    for (i = 0; i < keyidx; i++)
      {
	dbm_delete(dbm, keylist[i]);
	nDeleted++;
      }
    
    dbm_close(dbm);
    
    if (keyidx < KEYMAX)
      break;
    
  }
  
  ssl_mutex_off();
#if 0
  (void) fprintf(stderr, "Inter-Process Session Cache (DBM) Expiry: old: %d, new: %d, removed: %d", nElements, nElements-nDeleted, nDeleted);
#endif
  return;

}

void ssl_scache_remove(unsigned char *id, int idlen)
{
  DBM *dbm;
  datum dbmkey;
  
  /* create DBM key and values */
  dbmkey.dptr  = (char *)id;
  dbmkey.dsize = idlen;
  
  /* and delete it from the DBM file */
  ssl_mutex_on();
  if ((dbm = dbm_open(sess_file, O_RDWR, SSL_DBM_FILE_MODE)) == NULL)
    {
      (void) fprintf(stderr, "Cannot open SSLSessionCache DBM file `%s' for writing (delete)",sess_file);
      ssl_mutex_off();
      return;
    }
  
  dbm_delete(dbm, dbmkey);
  dbm_close(dbm);
  ssl_mutex_off();
  return;
  
}



SSL_SESSION *ssl_scache_retrieve(unsigned char *id, int idlen)
{
  DBM *dbm;
  datum dbmkey;
  datum dbmval;
  SSL_SESSION *sess = NULL;
  unsigned char *ucpData;
  int nData;
  time_t expiry;
  time_t now;
  
  /* allow the regular expiring to occur */
  ssl_scache_dbm_expire();
  
  /* create DBM key and values */
  dbmkey.dptr  = (char *)id;
  dbmkey.dsize = idlen;

  /* and fetch it from the DBM file */
  ssl_mutex_on();
  if ((dbm = dbm_open(sess_file, O_RDONLY, SSL_DBM_FILE_MODE)) == NULL)
    {
      (void) fprintf(stderr,"Cannot open SSLSessionCache DBM file `%s' for reading (fetch)",sess_file);
      
      ssl_mutex_off();
      return NULL;
    }

  dbmval = dbm_fetch(dbm, dbmkey);
  dbm_close(dbm);
  ssl_mutex_off();
  
  /* immediately return if not found */
  if (dbmval.dptr == NULL || dbmval.dsize <= sizeof(time_t))
    return NULL;
  
  /* parse resulting data */
  nData = dbmval.dsize-sizeof(time_t);
  ucpData = (unsigned char *)malloc(nData);
  if (ucpData == NULL)
    return NULL;
  
  memcpy(ucpData, (char *)dbmval.dptr+sizeof(time_t), nData);
  memcpy(&expiry, dbmval.dptr, sizeof(time_t));
  
  
  /* make sure the stuff is still not expired */
  now = time(NULL);
  if (expiry <= now) {
    ssl_scache_remove(id, idlen);
    return NULL;
  }
  
  /* unstreamed SSL_SESSION */
  sess = d2i_SSL_SESSION(NULL, &ucpData, nData);
  
  return sess;
}


unsigned int ssl_scache_store(unsigned char *id, int idlen,time_t expiry,SSL_SESSION *sess)
{
  datum dbmkey;
  datum dbmval;
  unsigned char ucaData[1024*10];
  int nData;
  unsigned char *ucp;
  DBM  *dbm;

  /* streamline session of data */
  ucp = ucaData;
  nData = i2d_SSL_SESSION(sess, &ucp);
  
  /* be careful : try not to store too much bytes in a DBM file */
  if((idlen + nData) >= 950)
    return 0;
  
  /* create DBM key */
  dbmkey.dptr = (char *)id;
  dbmkey.dsize = idlen;
  
  
  /* create DBM value */
  dbmval.dsize = sizeof(time_t) + nData;
  dbmval.dptr = (char *) malloc(dbmval.dsize);
  
  if(dbmval.dptr == NULL)
    return 0;
  
  memcpy((char *)dbmval.dptr,&expiry,sizeof(time_t));
  memcpy((char *)dbmval.dptr+sizeof(time_t),ucaData,nData);
  
  /* store it to the DBM file */
  ssl_mutex_on();
  
  if((dbm = dbm_open(sess_file,O_RDWR|O_CREAT,SSL_DBM_FILE_MODE)) == NULL)
    {
      (void) fprintf(stderr, "cannot open SSL Session Cache DBM file %s for writing\n", SESS_FILE);
      ssl_mutex_off();
      free(dbmval.dptr);
      return 0;
    }
  
  if(dbm_store(dbm,dbmkey,dbmval,DBM_INSERT)<0)
    {
      (void) fprintf(stderr, "cannot store SSL Session to DBM file %s \n",SESS_FILE);
      ssl_mutex_off();
      free(dbmval.dptr);
      return 0;
    }
  
  dbm_close(dbm);
  ssl_mutex_off();
  
  /* free the temperary buffers */
  free(dbmval.dptr);
  
  /* allow the regular expiring to occur */
  ssl_scache_dbm_expire();
  
  return 1;
}
/*
** borrowed from apache
** temporarily -- gkgodava@archie.uccs.edu
*/
char *SSL_SESSION_id2sz(unsigned char *id, int idlen)
{
  /*
  ** SSL_MAX_SSL_SESSION_ID_LENGTH is defined in ssl.h to be of 32
  */
  static char str[(SSL_MAX_SSL_SESSION_ID_LENGTH+1)*2];
  char *cp;
  int n;
  
  cp = str;
  
  for (n = 0; n < idlen && n < SSL_MAX_SSL_SESSION_ID_LENGTH; n++) {
    snprintf(cp, sizeof(str)-(cp-str), "%02X", id[n]);
    cp += 2;
  }
  
  *cp =(char) NULL;
  return str;
}

/*
** This callback function is executed by OPENSSL whenever a new SSL_sessiion is added to the internal
** session_cache. we use this hook to spread the SSL_session also to the inter processes disk-cache
** inorder to make share it with other processes
**/

int ssl_callback_NewSessionCacheEntry(SSL *ssl, SSL_SESSION  *pNew)
{
  long t;
  unsigned int flag;
  
  
  t = SSL_SESSION_CACHE_TIMEOUT;
  
  SSL_set_timeout(pNew,t);
  
  /*
  ** store the SSL_SESSION in the inter process cache with the same expire time, so that it expires automatically there too.
  */
  t = (SSL_get_time(pNew) + SSL_SESSION_CACHE_TIMEOUT);
  flag = ssl_scache_store(pNew->session_id, pNew->session_id_length, t, pNew);
  
  /*
  ** log the information
  */
#if 0
  (void) fprintf(stderr,"\n\n new session created for ssl context value id is %s \n",SSL_SESSION_id2sz(pNew->session_id,pNew->session_id_length));
#endif
  return 0;
}

/*
** This callback function is executed by OPENSSL whenever a new SSL_sessiion is looked up in the internal OpenSSL
** session_cache and it is not found. we use this hook to lookup the SSL_session in to the inter processes disk-cache
** where it might be stored by other processes
**/
SSL_SESSION *ssl_callback_GetSessionCacheEntry(SSL *ssl, unsigned char *id, int idlen, int *pCopy)
{
  SSL_SESSION *pSession;
  
  pSession = ssl_scache_retrieve(id,idlen);
  
  /*
  ** log the information
  */

#if 0
  if(pSession != NULL)
    (void) fprintf(stderr,"\n\n old  session of ssl context value id is %s is being lookfor is found \n",SSL_SESSION_id2sz(id,idlen));
  else
    (void) fprintf(stderr,"\n\n old  session of ssl context value id is %s is being lookfor is not found \n",SSL_SESSION_id2sz(id,idlen));
#endif
  
  *pCopy=0;
  return pSession;
}


/*
** This callback function is executed by OPENSSL whenever a new SSL_sessiion is removed from internal OpenSSL
** session_cache. we use this hook to remove the SSL_session from inter processes disk-cache
**/
void ssl_callback_DelSessionCacheEntry(SSL_CTX *ctx, SSL_SESSION *pSession)
{
  /*
  ** log the information
  */
  ssl_scache_remove(pSession->session_id, pSession->session_id_length);
  (void) fprintf(stderr,"\n\n session dead removing it ssl value id is %s is being being deleted \n",
		 SSL_SESSION_id2sz(pSession->session_id,pSession->session_id_length));
  
  return;
}