Extract a string between left boundary and right boundary

char* function_substr(char* source,char* lbound, char* rbound)
{

 char* lposition;
 char* rposition;
 int begin,end;
 int length;
 char* newstring;
 char* tmpstring;
  char* tmp;
  int i;
 int lblength = strlen(lbound);
 lposition = (char *)strstr(source, lbound);
 begin = (int)(lposition - source + 1);
 lr_output_message ("The lbound \"%s\" was found at position %d", lbound, begin);
 if(begin<0)
 {
  lr_output_message("ERROR:Verify Left boundary");
  return("-1");
 }
 begin = begin + lblength;
 rposition = (char *)strstr(source, rbound);
   end = (int)(rposition - source + 1);
 lr_output_message ("The rbound \"%s\" was found at position %d", rbound, end);
 length= end-begin;
if(length<0)
 {
        tmp = (char*)malloc(length + 1);
       tmp = (char*)strdup(source);
       for(i=1;i<begin;i++)
  {
   tmp++;
  }
  rposition = (char *)strstr(tmp, rbound);
  end = (int)(rposition - tmp + 1);
 //lr_output_message ("The new rbound \"%s\" was found at position %d", rbound, end);
  length= end - 1;
  if(length<0)
  {
   lr_output_message("ERROR: Verify right boundary value");
   return("-1");
  }
 }
  newstring = (char*)malloc(length+1);
  memset(newstring,'\0',length+1);
  tmpstring = (char*)strdup(source);
  for(i=1;i<begin;i++)
  {
   tmpstring++;
  }
  strncpy(newstring,tmpstring,length);
  //lr_output_message("Substring is ::>%s",newstring);
  return newstring;
       
}