parse_fline.c

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/*
 * $Id: parse_fline.c 4750 2008-08-27 14:22:55Z 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
 */

/*!
 * \file
 * \brief SIP first line parsing automaton
 * \ingroup parser
 */

#include "../dprint.h"
#include "msg_parser.h"
#include "parser_f.h"
#include "parse_methods.h"
#include "../mem/mem.h"
#include "../ut.h"

/* grammar:
   request  =  method SP uri SP version CRLF
   response =  version SP status  SP reason  CRLF
   (version = "SIP/2.0")
*/

/*known methods: INVITE, ACK, CANCEL, BYE*/

enum { START,
       INVITE1, INVITE2, INVITE3, INVITE4, INVITE5,
       ACK1, ACK2,
       CANCEL1, CANCEL2, CANCEL3, CANCEL4, CANCEL5,
       BYE1, BYE2,
       SIP1, SIP2, SIP3, SIP4, SIP5, SIP6,
       FIN_INVITE = 100, FIN_ACK, FIN_CANCEL, FIN_BYE, FIN_SIP,
       P_METHOD = 200, L_URI, P_URI, L_VER, 
       VER1, VER2, VER3, VER4, VER5, VER6, FIN_VER,
       L_STATUS, P_STATUS, L_REASON, P_REASON,
       L_LF, F_CR, F_LF
};

/* parses the first line, returns pointer to  next line  & fills fl;
   also  modifies buffer (to avoid extra copy ops) */
char* parse_first_line(char* buffer, unsigned int len, struct msg_start * fl)
{
   
   char *tmp;
   char* second;
   char* third;
   char* nl;
   unsigned int offset;
   /* int l; */
   char* end;
   char s1,s2,s3;
   char *prn;
   unsigned int t;

   /* grammar:
      request  =  method SP uri SP version CRLF
      response =  version SP status  SP reason  CRLF
      (version = "SIP/2.0")
   */
   

   end=buffer+len;
   /* see if it's a reply (status) */

   /* jku  -- parse well-known methods */

   /* drop messages which are so short they are for sure useless;
           utilize knowledge of minimum size in parsing the first
      token 
        */
   if (len <=16 ) {
      LM_INFO("message too short: %d\n", len);
      goto error1;
   }

   tmp=buffer;
   /* is it perhaps a reply, ie does it start with "SIP...." ? */
   if (  (*tmp=='S' || *tmp=='s') && 
      strncasecmp( tmp+1, SIP_VERSION+1, SIP_VERSION_LEN-1)==0 &&
      (*(tmp+SIP_VERSION_LEN)==' ')) {
         fl->type=SIP_REPLY;
         fl->u.reply.version.len=SIP_VERSION_LEN;
         tmp=buffer+SIP_VERSION_LEN;
   } else IFISMETHOD( INVITE, 'I' )
   else IFISMETHOD( CANCEL, 'C')
   else IFISMETHOD( ACK, 'A' )
   else IFISMETHOD( BYE, 'B' ) 
   else IFISMETHOD( INFO, 'I' )
   /* if you want to add another method XXX, include METHOD_XXX in
           H-file (this is the value which you will take later in
           processing and define XXX_LEN as length of method name;
      then just call IFISMETHOD( XXX, 'X' ) ... 'X' is the first
      latter; everything must be capitals
   */
   else {
      /* neither reply, nor any of known method requests, 
         let's believe it is an unknown method request
         */
      tmp=eat_token_end(buffer,buffer+len);
      if ((tmp==buffer)||(tmp>=end)){
         LM_INFO("empty  or bad first line\n");
         goto error1;
      }
      if (*tmp!=' ') {
         LM_INFO("method not followed by SP\n");
         goto error1;
      }
      fl->type=SIP_REQUEST;
      /* see if it is another known method */
      /* fl->u.request.method_value=METHOD_OTHER; */
      if(parse_method(buffer, tmp,
            (unsigned int*)&fl->u.request.method_value)==0)
      {
         LM_INFO("failed to parse the method\n");
         goto error1;
      }
      fl->u.request.method.len=tmp-buffer;
   }
   

   /* identifying type of message over now; 
      tmp points at space after; go ahead */

   fl->u.request.method.s=buffer;  /* store ptr to first token */
   second=tmp+1;        /* jump to second token */
   offset=second-buffer;

/* EoJku */
   
   /* next element */
   tmp=eat_token_end(second, second+len-offset);
   if (tmp>=end){
      goto error;
   }
   offset+=tmp-second;
   third=eat_space_end(tmp, tmp+len-offset);
   offset+=third-tmp;
   if ((third==tmp)||(tmp>=end)){
      goto error;
   }
   fl->u.request.uri.s=second;
   fl->u.request.uri.len=tmp-second;

   /* jku: parse status code */
   if (fl->type==SIP_REPLY) {
      if (fl->u.request.uri.len!=3) {
         LM_INFO("len(status code)!=3: %.*s\n",
            fl->u.request.uri.len, ZSW(second) );
         goto error;
      }
      s1=*second; s2=*(second+1);s3=*(second+2);
      if (s1>='0' && s1<='9' && 
          s2>='0' && s2<='9' &&
          s3>='0' && s3<='9' ) {
         fl->u.reply.statuscode=(s1-'0')*100+10*(s2-'0')+(s3-'0');
      } else {
         LM_INFO("status_code non-numerical: %.*s\n",
            fl->u.request.uri.len, ZSW(second) );
         goto error;
      }
   }
   /* EoJku */

   /*  last part: for a request it must be the version, for a reply
    *  it can contain almost anything, including spaces, so we don't care
    *  about it*/
   if (fl->type==SIP_REQUEST){
      tmp=eat_token_end(third,third+len-offset);
      offset+=tmp-third;
      if ((tmp==third)||(tmp>=end)){
         goto error;
      }
      if (! is_empty_end(tmp, tmp+len-offset)){
         goto error;
      }
   }else{
      tmp=eat_token2_end(third,third+len-offset,'\r'); /* find end of line 
                                      ('\n' or '\r') */
      if (tmp>=end){ /* no crlf in packet => invalid */
         goto error;
      }
      offset+=tmp-third;
   }
   nl=eat_line(tmp,len-offset);
   if (nl>=end){ /* no crlf in packet or only 1 line > invalid */
      goto error;
   }
   fl->u.request.version.s=third;
   fl->u.request.version.len=tmp-third;
   fl->len=nl-buffer;

   return nl;

error:
   LM_ERR("bad %s first line\n",
      (fl->type==SIP_REPLY)?"reply(status)":"request");

   LM_ERR("at line 0 char %d: \n", offset );
   prn=pkg_malloc( offset );
   if (prn) {
      for (t=0; t<offset; t++)
         if (*(buffer+t)) *(prn+t)=*(buffer+t);
         else *(prn+t)='°';
      LM_ERR("parsed so far: %.*s\n", offset, ZSW(prn) );
      pkg_free( prn );
   };
error1:
   fl->type=SIP_INVALID;
   LM_INFO("bad message\n");
   /* skip  line */
   nl=eat_line(buffer,len);
   return nl;
}