HttpUtil.java

package ar.com.javacuriosities.nio.server.http.util;

import java.io.UnsupportedEncodingException;

public class HttpUtil {

    private static final byte[] CONTENT_LENGTH = new byte[]{'C','o','n','t','e','n','t','-','L','e','n','g','t','h'};

    public static int parseHttpRequest(byte[] src, int startIndex, int endIndex, HttpHeaders httpHeaders){
        // Parseamos la línea de HTTP request
        int endOfFirstLine = findNextLineBreak(src, startIndex, endIndex);
        if(endOfFirstLine == -1) return -1;


        // Parseamos HTTP headers
        int prevEndOfHeader = endOfFirstLine + 1;
        int endOfHeader = findNextLineBreak(src, prevEndOfHeader, endIndex);

        while(endOfHeader != -1 && endOfHeader != prevEndOfHeader + 1){ // prevEndOfHeader + 1 = end of previous header + 2 (+2 = CR + LF)
            if(matches(src, prevEndOfHeader, CONTENT_LENGTH)){
                try {
                    findContentLength(src, prevEndOfHeader, endIndex, httpHeaders);
                } catch (UnsupportedEncodingException e) {
                    e.printStackTrace();
                }
            }

            prevEndOfHeader = endOfHeader + 1;
            endOfHeader = findNextLineBreak(src, prevEndOfHeader, endIndex);
        }

        if(endOfHeader == -1){
            return -1;
        }

        // Verificamos contengo un mensaje completo de HTTP
        int bodyStartIndex = endOfHeader + 1;
        int bodyEndIndex  = bodyStartIndex + httpHeaders.contentLength;

		if (bodyEndIndex <= endIndex) {
			// Byte array contains a full HTTP request
			httpHeaders.bodyStartIndex = bodyStartIndex;
			httpHeaders.bodyEndIndex = bodyEndIndex;
			return bodyEndIndex;
		}

		return -1;
	}

    private static void findContentLength(byte[] src, int startIndex, int endIndex, HttpHeaders httpHeaders) throws UnsupportedEncodingException {
        int indexOfColon = findNext(src, startIndex, endIndex, (byte) ':');

        // Skip espacios despues del ";"
        int index = indexOfColon +1;
        while(src[index] == ' '){
            index++;
        }

        int valueStartIndex = index;
        int valueEndIndex   = index;
        boolean endOfValueFound = false;

		while (index < endIndex && !endOfValueFound) {
			switch (src[index]) {
			case '0':
				;
			case '1':
				;
			case '2':
				;
			case '3':
				;
			case '4':
				;
			case '5':
				;
			case '6':
				;
			case '7':
				;
			case '8':
				;
			case '9': {
				index++;
				break;
			}

			default: {
				endOfValueFound = true;
				valueEndIndex = index;
			}
			}
		}

        httpHeaders.contentLength = Integer.parseInt(new String(src, valueStartIndex, valueEndIndex - valueStartIndex, "UTF-8"));
    }

    private static int findNext(byte[] src, int startIndex, int endIndex, byte value){
        for(int index = startIndex; index < endIndex; index++){
            if(src[index] == value) return index;
        }
        return -1;
    }

    private static int findNextLineBreak(byte[] src, int startIndex, int endIndex) {
        for(int index = startIndex; index < endIndex; index++){
            if(src[index] == '\n'){
                if(src[index - 1] == '\r'){
                    return index;
                }
            };
        }
        return -1;
    }

    private static boolean matches(byte[] src, int offset, byte[] value){
        for(int i=offset, n=0; n < value.length; i++, n++){
            if(src[i] != value[n]) return false;
        }
        return true;
    }
}