EscapeUtil

EscapeUtil.java

package com.thisismydesign;

import org.apache.commons.codec.binary.Hex;

import java.util.regex.Matcher;
import java.util.regex.Pattern;

public final class EscapeUtil {

    private final static Pattern pipe = Pattern.compile("\\|");
    private final static Pattern snortSpecial = Pattern.compile("[\";\\\\]");
    private final static Pattern nonASCII = Pattern.compile("[^\\p{InBasic_Latin}]");
    private final static Pattern specialOrWhiteSpaceExceptSpace = Pattern.compile("[\\p{C}\\p{Z}&&[^ ]]");
    // Order of things is important, all successful escapes will create pipes (|)
    // so the actual ones we should escape in the beginning
    private final static Pattern[] patterns = new Pattern[]{pipe, snortSpecial, nonASCII,
            specialOrWhiteSpaceExceptSpace};

    private EscapeUtil(){}

    public static String escapeAll(String string) {
        String escaped = string;

        for (Pattern pattern : patterns) {
            escaped = escape(escaped, pattern);
        }

        return mergePipes(escaped);
    }

    private static String escape(String string, Pattern pattern) {
        Matcher matcher = pattern.matcher(string);
        StringBuffer sb = new StringBuffer();
        while (matcher.find()) {
            matcher.appendReplacement(sb, getReplacement(matcher.group(0)));
        }
        matcher.appendTail(sb);
        return sb.toString();
    }

    private static String getReplacement(String string) {
        return betweenPipes(toHex(string));
    }

    private static String toHex(String string) {
        return Hex.encodeHexString(string.getBytes());
    }

    private static String betweenPipes(String string) {
        return "|" + string + "|";
    }

    private static String mergePipes(String string) {
        return string.replaceAll("\\|\\|", " ");
    }

}

EscapeUtilTest.java

package com.thisismydesign;

import org.apache.commons.lang3.StringEscapeUtils;
import org.junit.Ignore;
import org.junit.Test;

import static org.junit.Assert.*;

public class EscapeUtilTest {

    @Test
    public void escapeAll_withPipe() throws Exception {
        assertEquals("|7c|", EscapeUtil.escapeAll("|"));
        assertEquals("hello|7c|there", EscapeUtil.escapeAll("hello|there"));
        assertEquals("hello|7c 7c|there", EscapeUtil.escapeAll("hello||there"));
        assertEquals("hello|7c|there|7c|you", EscapeUtil.escapeAll("hello|there|you"));
    }

    @Test
    public void escapeAll_withSpecialSnortChars() throws Exception {
        assertEquals("hi|22|there", EscapeUtil.escapeAll("hi\"there"));
        assertEquals("hi|3b|there", EscapeUtil.escapeAll("hi;there"));
        assertEquals("hi|5c|there", EscapeUtil.escapeAll("hi\\there"));
    }

    @Test
    public void escapeAll_withNotPrintable() throws Exception {
        assertEquals("|00|", EscapeUtil.escapeAll(Character.toString((char) 0)));
        assertEquals("|00|hi", EscapeUtil.escapeAll(StringEscapeUtils.unescapeJava("\\u0000") + "hi"));
        assertEquals("hi|00|there", EscapeUtil.escapeAll("hi" + StringEscapeUtils.unescapeJava("\\u0000") + "there"));
    }

    @Test
    @Ignore
    public void escapeAll_withUnicodeReplacementChar() throws Exception {
        assertEquals("hi|efbfbd|there", EscapeUtil.escapeAll("hi" + StringEscapeUtils.unescapeJava("\\ufffd") + "there"));
        assertEquals("hi|efbfbd|there", EscapeUtil.escapeAll("hi�there"));
    }

    @Test
    public void escapeAll_withWhitespace() throws Exception {
        assertEquals("hi there", EscapeUtil.escapeAll("hi there"));
        assertEquals("hi|09|there", EscapeUtil.escapeAll("hi\tthere"));
        assertEquals("hi|0a|there", EscapeUtil.escapeAll("hi\nthere"));
        assertEquals("hi|0a|there", EscapeUtil.escapeAll("hi" + StringEscapeUtils.unescapeJava("\\u000a") + "there"));
    }

    @Test
    @Ignore
    public void escapeAll_withNonASCII() throws Exception {
        assertEquals("hi|c3a1|there", EscapeUtil.escapeAll("hiáthere"));
    }
}