maxfwd.c

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/*
 * $Id: maxfwd.c 4949 2008-09-18 12:02:39Z henningw $
 *
 * MAXFWD module
 *
 * Copyright (C) 2001-2003 FhG Fokus
 *
 * This file is part of Kamailio, a free SIP server.
 *
 * Kamailio 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 2 of the License, or
 * (at your option) any later version
 *
 * Kamailio 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * History:
 * --------
 *  2003-03-11  updated to the new module interface (andrei)
 *  2003-03-16  flags export parameter added (janakj)
 *  2003-03-19  all mallocs/frees replaced w/ pkg_malloc/pkg_free (andrei)
 *  2004-08-15  max value of max-fwd header is configurable via max_limit
 *              module param (bogdan)
 *  2005-09-15  max_limit param cannot be disabled anymore (according to RFC)
 *              (bogdan)
 *  2005-11-03  is_maxfwd_lt() function added; MF value saved in 
 *              msg->maxforwards->parsed (bogdan)
 */


#include <stdio.h>
#include <string.h>
#include <stdlib.h>

#include "../../sr_module.h"
#include "../../dprint.h"
#include "../../error.h"
#include "../../ut.h"
#include "../../mem/mem.h"
#include "mf_funcs.h"

MODULE_VERSION

#define MAXFWD_UPPER_LIMIT 256

static int max_limit = MAXFWD_UPPER_LIMIT;

static int fixup_maxfwd_header(void** param, int param_no);
static int w_process_maxfwd_header(struct sip_msg* msg,char* str,char* str2);
static int is_maxfwd_lt(struct sip_msg *msg, char *slimit, char *foo);
static int mod_init(void);

static cmd_export_t cmds[]={
   {"mf_process_maxfwd_header", (cmd_function)w_process_maxfwd_header, 1,
      fixup_maxfwd_header, 0, REQUEST_ROUTE},
   {"is_maxfwd_lt", (cmd_function)is_maxfwd_lt, 1,
      fixup_maxfwd_header, 0, REQUEST_ROUTE|FAILURE_ROUTE|BRANCH_ROUTE},
   {0,0,0,0,0,0}
};

static param_export_t params[]={
   {"max_limit",    INT_PARAM,  &max_limit},
   {0,0,0}
};



struct module_exports exports= {
   "maxfwd",
   DEFAULT_DLFLAGS, /* dlopen flags */
   cmds,
   params,
   0,          /* exported statistics */
   0,          /* exported MI functions */
   0,          /* exported pseudo-variables */
   0,          /* extra processes */
   mod_init,
   0,
   0,
   0           /* per-child init function */
};



static int mod_init(void)
{
   if ( max_limit<1 || max_limit>MAXFWD_UPPER_LIMIT ) {
      LM_ERR("invalid max limit (%d) [1,%d]\n",
         max_limit,MAXFWD_UPPER_LIMIT);
      return E_CFG;
   }
   return 0;
}



static int fixup_maxfwd_header(void** param, int param_no)
{
   unsigned long code;
   int err;

   if (param_no==1){
      code=str2s(*param, strlen(*param), &err);
      if (err==0){
         if (code<1 || code>MAXFWD_UPPER_LIMIT){
            LM_ERR("invalid MAXFWD number <%ld> [1,%d]\n",
               code,MAXFWD_UPPER_LIMIT);
            return E_UNSPEC;
         }
         if (code>max_limit) {
            LM_ERR("default value <%ld> bigger than max limit(%d)\n",
               code, max_limit);
            return E_UNSPEC;
         }
         pkg_free(*param);
         *param=(void*)code;
         return 0;
      }else{
         LM_ERR("bad  number <%s>\n",(char*)(*param));
         return E_UNSPEC;
      }
   }
   return 0;
}



static int w_process_maxfwd_header(struct sip_msg* msg, char* str1,char* str2)
{
   int val;
   str mf_value;

   val=is_maxfwd_present(msg, &mf_value);
   switch (val) {
      /* header not found */
      case -1:
         if (add_maxfwd_header( msg, (unsigned int)(unsigned long)str1)!=0)
            goto error;
         return 2;
      /* error */
      case -2:
         break;
      /* found */
      case 0:
         return -1;
      default:
         if (val>max_limit){
            LM_DBG("value %d decreased to %d\n", val, max_limit);
            val = max_limit+1;
         }
         if ( decrement_maxfwd(msg, val, &mf_value)!=0 ) {
            LM_ERR("decrement failed!\n");
            goto error;
         }
   }

   return 1;
error:
   return -2;
}



static int is_maxfwd_lt(struct sip_msg *msg, char *slimit, char *foo)
{
   str mf_value;
   int limit;
   int val;

   limit = (int)(long)slimit;
   val = is_maxfwd_present( msg, &mf_value);
   LM_DBG("value = %d \n",val);

   if ( val<0 ) {
      /* error or not found */
      return val-1;
   } else if ( val>=limit ) {
      /* greater or equal than/to limit */
      return -1;
   }

   return 1;
}