modules_k/maxfwd/maxfwd.c

/*
 * $Id$
 *
 * 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"
#include "api.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);

int bind_maxfwd(maxfwd_api_t *api);

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},
        {"bind_maxfwd",  (cmd_function)bind_maxfwd,  0,
                0, 0, 0},
        {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;
}


int process_maxfwd_header(struct sip_msg *msg, int limit)
{
        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)limit)!=0)
                                goto error;
                        return 2;
                /* error */
                case -2:
                        goto error;
                /* 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 w_process_maxfwd_header(struct sip_msg* msg, char* str1, char* str2)
{
        return process_maxfwd_header(msg, (int)(unsigned long)str1);
}


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;
}

int bind_maxfwd(maxfwd_api_t *api)
{
        if (!api) {
                ERR("Invalid parameter value\n");
                return -1;
        }
        api->process_maxfwd = process_maxfwd_header;

        return 0;
}