mf_funcs.c

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/*
 * $Id: mf_funcs.c 5252 2008-11-24 17:50:16Z henningw $
 *
 * 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:
 * ----------
 * 2003-02-28 scratchpad compatibility abandoned (jiri)
 * 2002-01-28 scratchpad removed (jiri)
 * 2004-08-15 max value of max-fwd header is configurable (bogdan)
 * 2005-11-03 MF value saved in msg->maxforwards->parsed (bogdan)
 */


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

#include "mf_funcs.h"
#include "../../mem/mem.h"
#include "../../ut.h"
#include "../../data_lump.h"


#define MF_HDR "Max-Forwards: "
#define MF_HDR_LEN (sizeof(MF_HDR) - 1)

/* do a tricky thing and keep the parsed value of MAXFWD hdr incremented 
 * by one in order to make difference between 0 (not set)
 * and 0 (zero value) - bogdan */
#define IS_MAXWD_STORED(_msg_) \
   ((_msg_)->maxforwards->parsed)
#define STORE_MAXWD_VAL(_msg_,_val_) \
   (_msg_)->maxforwards->parsed = ((void*)(long)((_val_)+1))
#define FETCH_MAXWD_VAL(_msg_) \
   (((int)(long)(_msg_)->maxforwards->parsed)-1)

/* looks for the MAX FORWARDS header
   returns the its value, -1 if is not present or -2 for error */
int is_maxfwd_present( struct sip_msg* msg , str *foo)
{
   int x, err;

   /* lookup into the message for MAX FORWARDS header*/
   if ( !msg->maxforwards ) {
      if  ( parse_headers( msg , HDR_MAXFORWARDS_F, 0 )==-1 ){
         LM_ERR("parsing MAX_FORWARD header failed!\n");
         return -2;
      }
      if (!msg->maxforwards) {
         LM_DBG("max_forwards header not found!\n");
         return -1;
      }
   } else if (IS_MAXWD_STORED(msg)) {
      trim_len( foo->len , foo->s , msg->maxforwards->body );
      return FETCH_MAXWD_VAL(msg);
   }

   /* if header is present, trim to get only the string containing numbers */
   trim_len( foo->len , foo->s , msg->maxforwards->body );

   /* convert from string to number */
   x = str2s( foo->s,foo->len,&err);
   if (err){
      LM_ERR("unable to parse the max forwards number\n");
      return -2;
   }
   /* store the parsed values */
   STORE_MAXWD_VAL(msg, x);
   LM_DBG("value = %d \n",x);
   return x;
}



int decrement_maxfwd( struct sip_msg* msg , int x, str *s)
{
   int i;

   /* decrement the value */
   x--;

   /* update the stored value */
   STORE_MAXWD_VAL(msg, x);

   /*rewriting the max-fwd value in the message (buf and orig)*/
   for(i = s->len - 1; i >= 0; i--) {
      s->s[i] = (x % 10) + '0';
      x /= 10;
      if (x==0) {
         i = i - 1;
         break;
      }
   }
   while(i >= 0) s->s[i--] = ' ';

   return 0;
}

static inline int btostr( char *p,  unsigned char val)
{
   unsigned int a,b,i =0;

   if ( (a=val/100)!=0 )
      *(p+(i++)) = a+'0';         /*first digit*/
   if ( (b=val%100/10)!=0 || a)
      *(p+(i++)) = b+'0';        /*second digit*/
   *(p+(i++)) = '0'+val%10;              /*third digit*/

   return i;
}

int add_maxfwd_header( struct sip_msg* msg , unsigned int val )
{
   unsigned int  len;
   char          *buf;
   struct lump*  anchor;

   /* constructing the header */
   len = MF_HDR_LEN /*"MAX-FORWARDS: "*/+ CRLF_LEN + 3/*val max on 3 digits*/;

   buf = (char*)pkg_malloc( len );
   if (!buf) {
      LM_ERR("add_maxfwd_header: no more pkg memory\n");
      goto error;
   }
   memcpy( buf , MF_HDR, MF_HDR_LEN );
   len = MF_HDR_LEN ;
   len += btostr( buf+len , val );
   memcpy( buf+len , CRLF , CRLF_LEN );
   len +=CRLF_LEN;

   /*inserts the header at the beginning of the message*/
   anchor = anchor_lump(msg, msg->headers->name.s - msg->buf, 0 , 0);
   if (anchor == 0) {
      LM_ERR("add_maxfwd_header: failed to get anchor\n");
      goto error1;
   }

   if (insert_new_lump_before(anchor, buf, len, 0) == 0) {
      LM_ERR("add_maxfwd_header: failed to insert MAX-FORWARDS lump\n");
      goto error1;
   }

   return 0;
error1:
   pkg_free( buf );
error:
   return -1;
}