ValidatingValidator.java :  » Messenger » gfix » org » gfix » parser » Java Open Source

package org.gfix.parser;


public class ValidatingValidator implements FixMessageValidator
{
  public static final int FIX_VERSION = 8;
  public static final String FIX_VERSION_VALUE = "FIX";
  public static final int FIX_MESSAGE_LENTGH = 9;
  public static final int FIX_MESSAGE_TYPE = 35;
  public static final int FIX_CHECK_SUM  = 10;
  
  private static final Rule[] firstTagRules = new Rule[]{
    new Tag8MustBeFirstRule(),
    new Tag9MustBeSecondRule(),
    new Tag35MustBeThirdRule()
  };
  
  private int length;
  boolean startedMessage;
  private int numberOfTagsSeen;
  private int bytesSeen;
  private int sumOfBytesSeen;
  
  
  
  private ValidatingValidator(){init();}

  @Override
  public FixParseFault validate(int tag, String contents)
  {
    // generate the checksum
    if(tag != FIX_CHECK_SUM)
    {
      // the tag itself
      for(byte b : String.valueOf(tag).getBytes())
      {
        sumOfBytesSeen += b;
      }
      sumOfBytesSeen += FixParser.FIX_CONTENT;
      for(byte b : String.valueOf(contents).getBytes())
      {
        sumOfBytesSeen += b;
      }  
      // the delimiter
      sumOfBytesSeen += FixParser.FIX_DELIMITER;
    }
    
    if(numberOfTagsSeen < firstTagRules.length)
    {
      FixParseFault fault = firstTagRules[numberOfTagsSeen].validate(tag, contents);
      if(fault != null)
      {
        return fault;
      }
    }
    numberOfTagsSeen++;
    switch(tag)
    {
      case FIX_VERSION:
      {
        if(startedMessage)
        {
          return new FixParseFault(tag,"Fix version already supplied",
              -1,contents,FixParseFault.Serverity.ERROR);
        }
        
        startedMessage = true;
        if(contents == null || contents.length() == 0)
        {
          return new FixParseFault(tag,"Fix version must be supplied",
              -1,contents,FixParseFault.Serverity.ERROR);
        }
        else if(!contents.startsWith(FIX_VERSION_VALUE))
        {
          return new FixParseFault(tag,"Fix version does not start with fix",
              -1,contents,FixParseFault.Serverity.WARNING);
        }
        break;
      }
      case FIX_MESSAGE_LENTGH:
      {
        if(length!= -1)
        {
          return new FixParseFault(tag,"Message length already supplied",
              -1,contents,FixParseFault.Serverity.ERROR);
        }
        try
        {
          length = Integer.valueOf(contents);
        }
        catch(NumberFormatException nfe)
        {
          return new FixParseFault(tag,"Message length supplied was not a number",
              -1,contents,FixParseFault.Serverity.ERROR);
        }
        break;
      }
      case FIX_CHECK_SUM:
      {
        //first check the length against the claimed length
        if(bytesSeen != length)
        {
          return new FixParseFault(tag,"Message length supplied was not a correct",
              -1,contents,FixParseFault.Serverity.ERROR);
        }
        // check the checksum
        
        int calculated = sumOfBytesSeen % 256;
        try
        {
          int givenChecksum = Integer.valueOf(contents);
          init();
          if(calculated != givenChecksum)
          {
            return new FixParseFault(tag,"Message checksum supplied was not a the same as the calculated: " + calculated,
                -1,contents,FixParseFault.Serverity.ERROR);
          }
        }
        catch(NumberFormatException nfe)
        {
          return new FixParseFault(tag,"Message checksum supplied was not a number",
              -1,contents,FixParseFault.Serverity.ERROR);
        }
        
        // this message is done reset the sucker;
        init();
        break;
      }
      default:
        bytesSeen += String.valueOf(tag).getBytes().length + contents.getBytes().length + 2;
      break;
      
    }
    return null;
  }

  private void init()
  {
    length = -1;
    startedMessage = false;
    numberOfTagsSeen = 0;
    bytesSeen = 0;
    sumOfBytesSeen = 0;
  }
  
  private static interface Rule
  {
    FixParseFault validate(int tag, String contents);
  }
  
  private static class Tag8MustBeFirstRule implements Rule
  {
    public FixParseFault validate(int tag, String contents)
    {
      if( tag != FIX_VERSION)
      {
        return new FixParseFault(tag,"Fix messages must start with 8=",
          -1,contents,FixParseFault.Serverity.ERROR);
      }
      return null;
    }
  }
  
  private static class Tag9MustBeSecondRule  implements Rule
  {
    public FixParseFault validate(int tag, String contents)
    {
      if( tag != FIX_MESSAGE_LENTGH)
      {
        return new FixParseFault(tag,"Fix messages must contain 9=XX as the second tag",
            -1,contents,FixParseFault.Serverity.WARNING);
      }
      return null;
    }
  }
  
  private static class Tag35MustBeThirdRule  implements Rule
  {
    public FixParseFault validate(int tag, String contents)
    {
      if( tag != FIX_MESSAGE_TYPE)
      {
        return new FixParseFault(tag,"Fix messages must contain 35=XX as the third tag",
            -1,contents,FixParseFault.Serverity.WARNING);
      }
      return null;
    }
  }
  
  public static class Factory implements FixMessageValidatorFactory
  {
    public FixMessageValidator getFixMessageValidator()
    {
      return new ValidatingValidator();
    }
  }
  
  
}