MetaDataBuilder.java

package com.firefly.codec.http2.hpack;

import com.firefly.codec.http2.model.BadMessageException;
import com.firefly.codec.http2.model.HostPortHttpField;
import com.firefly.codec.http2.model.HttpField;
import com.firefly.codec.http2.model.HttpFields;
import com.firefly.codec.http2.model.HttpHeader;
import com.firefly.codec.http2.model.HttpScheme;
import com.firefly.codec.http2.model.HttpStatus;
import com.firefly.codec.http2.model.HttpVersion;
import com.firefly.codec.http2.model.MetaData;
import com.firefly.codec.http2.model.StaticTableHttpField;

public class MetaDataBuilder {
	private final int _maxSize;
	private int _size;
	private int _status;
	private String _method;
	private HttpScheme _scheme;
	private HostPortHttpField _authority;
	private String _path;
	private long _contentLength = Long.MIN_VALUE;
	private HttpFields _fields = new HttpFields(10);

	/**
	 * @param maxHeadersSize
	 *            The maximum size of the headers, expressed as total name and
	 *            value characters.
	 */
	MetaDataBuilder(int maxHeadersSize) {
		_maxSize = maxHeadersSize;
	}

	/**
	 * Get the maxSize.
	 * 
	 * @return the maxSize
	 */
	public int getMaxSize() {
		return _maxSize;
	}

	/**
	 * Get the size.
	 * 
	 * @return the current size in bytes
	 */
	public int getSize() {
		return _size;
	}

	public void emit(HttpField field) {
		HttpHeader header = field.getHeader();
		String name = field.getName();
		String value = field.getValue();
		int field_size = name.length() + (value == null ? 0 : value.length());
		_size += field_size + 32;
		if (_size > _maxSize)
			throw new BadMessageException(HttpStatus.REQUEST_HEADER_FIELDS_TOO_LARGE_431,
					"Header size " + _size + ">" + _maxSize);

		if (field instanceof StaticTableHttpField) {
			StaticTableHttpField staticField = (StaticTableHttpField) field;
			switch (header) {
			case C_STATUS:
				_status = (Integer) staticField.getStaticValue();
				break;

			case C_METHOD:
				_method = value;
				break;

			case C_SCHEME:
				_scheme = (HttpScheme) staticField.getStaticValue();
				break;

			default:
				throw new IllegalArgumentException(name);
			}
		} else if (header != null) {
			switch (header) {
			case C_STATUS:
				_status = field.getIntValue();
				break;

			case C_METHOD:
				_method = value;
				break;

			case C_SCHEME:
				if (value != null)
					_scheme = HttpScheme.CACHE.get(value);
				break;

			case C_AUTHORITY:
				if (field instanceof HostPortHttpField)
					_authority = (HostPortHttpField) field;
				else if (value != null)
					_authority = new AuthorityHttpField(value);
				break;

			case HOST:
				// :authority fields must come first. If we have one, ignore the
				// host header as far as authority goes.
				if (_authority == null) {
					if (field instanceof HostPortHttpField)
						_authority = (HostPortHttpField) field;
					else if (value != null)
						_authority = new AuthorityHttpField(value);
				}
				_fields.add(field);
				break;

			case C_PATH:
				_path = value;
				break;

			case CONTENT_LENGTH:
				_contentLength = field.getLongValue();
				_fields.add(field);
				break;

			default:
				if (name.charAt(0) != ':')
					_fields.add(field);
				break;
			}
		} else {
			if (name.charAt(0) != ':')
				_fields.add(field);
		}
	}

	public MetaData build() {
		try {
			HttpFields fields = _fields;
			_fields = new HttpFields(Math.max(10, fields.size() + 5));

			if (_method != null)
				return new MetaData.Request(_method, _scheme, _authority, _path, HttpVersion.HTTP_2, fields,
						_contentLength);
			if (_status != 0)
				return new MetaData.Response(HttpVersion.HTTP_2, _status, fields, _contentLength);
			return new MetaData(HttpVersion.HTTP_2, fields, _contentLength);
		} finally {
			_status = 0;
			_method = null;
			_scheme = null;
			_authority = null;
			_path = null;
			_size = 0;
			_contentLength = Long.MIN_VALUE;
		}
	}

	/**
	 * Check that the max size will not be exceeded.
	 * 
	 * @param length
	 *            the length
	 * @param huffman
	 *            the huffman name
	 */
	public void checkSize(int length, boolean huffman) {
		// Apply a huffman fudge factor
		if (huffman)
			length = (length * 4) / 3;
		if ((_size + length) > _maxSize)
			throw new BadMessageException(HttpStatus.REQUEST_HEADER_FIELDS_TOO_LARGE_431,
					"Header size " + (_size + length) + ">" + _maxSize);
	}
}