ru.mystamps.web.validation.jsr303.ImageFileValidator.java Source code

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Here is the source code for ru.mystamps.web.validation.jsr303.ImageFileValidator.java

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/*
 * Copyright (C) 2009-2017 Slava Semushin <slava.semushin@gmail.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 */
package ru.mystamps.web.validation.jsr303;

import java.io.IOException;
import java.io.InputStream;
import java.util.Arrays;

import javax.validation.ConstraintValidator;
import javax.validation.ConstraintValidatorContext;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import org.springframework.web.multipart.MultipartFile;

public class ImageFileValidator implements ConstraintValidator<ImageFile, MultipartFile> {

    private static final Logger LOG = LoggerFactory.getLogger(ImageFileValidator.class);

    private static final String JPEG_CONTENT_TYPE = "image/jpeg";
    private static final String PNG_CONTENT_TYPE = "image/png";

    // see https://en.wikipedia.org/wiki/JPEG#Syntax_and_structure
    // CheckStyle: ignore NoWhitespaceAfterCheck for next 3 lines
    private static final byte[][] JPEG_SIGNATURES = { { (byte) 0xFF, (byte) 0xD8, (byte) 0xFF, (byte) 0xE0 },
            { (byte) 0xFF, (byte) 0xD8, (byte) 0xFF, (byte) 0xE1 } };

    // see https://en.wikipedia.org/wiki/Portable_Network_Graphics#File_header
    private static final byte[] PNG_FIRST_PART_SIGNATURE = new byte[] { (byte) 0x89, 0x50, 0x4E, 0x47 };

    private static final byte[] PNG_SECOND_PART_SIGNATURE = new byte[] { 0x0D, 0x0A, 0x1A, 0x0A };

    private static boolean isJpeg(byte[] bytes) {
        // TODO: also check that last 2 bytes are FF D9 (use RandomAccessFile)

        for (byte[] signature : JPEG_SIGNATURES) {
            if (Arrays.equals(bytes, signature)) {
                return true;
            }
        }

        return false;
    }

    private static boolean doesItLookLikePng(byte[] bytes) {
        return Arrays.equals(bytes, PNG_FIRST_PART_SIGNATURE);
    }

    private static boolean isItReallyPng(byte[] bytes) {
        return Arrays.equals(bytes, PNG_SECOND_PART_SIGNATURE);
    }

    private static byte[] readFourBytes(InputStream is) {
        // CheckStyle: ignore MagicNumber for next 1 line
        byte[] bytes = new byte[4];
        try {
            int read = is.read(bytes, 0, bytes.length);
            if (read != bytes.length) {
                return null;
            }

            return bytes;

        } catch (IOException e) {
            LOG.warn("Error during reading from file: {}", e.getMessage());
            return null;
        }
    }

    private static String formatBytes(byte[] bytes) {
        // CheckStyle: ignore MagicNumber for next 1 line
        return String.format("%02x %02x %02x %02x", bytes[0], bytes[1], bytes[2], bytes[3]);
    }

    @Override
    public void initialize(ImageFile annotation) {
        // Intentionally empty: nothing to initialize
    }

    @Override
    @SuppressWarnings("PMD.CyclomaticComplexity")
    public boolean isValid(MultipartFile file, ConstraintValidatorContext ctx) {

        if (file == null) {
            return true;
        }

        if (file.isEmpty()) {
            return false;
        }

        String contentType = file.getContentType();
        if (!PNG_CONTENT_TYPE.equals(contentType) && !JPEG_CONTENT_TYPE.equals(file.getContentType())) {
            LOG.debug("Reject file with content type '{}'", contentType);
            return false;
        }

        try (InputStream stream = file.getInputStream()) {

            byte[] firstPart = readFourBytes(stream);
            if (firstPart == null) {
                LOG.warn("Failed to read 4 bytes from file");
                return false;
            }

            if (isJpeg(firstPart)) {
                return true;
            }

            if (doesItLookLikePng(firstPart)) {
                byte[] secondPart = readFourBytes(stream);
                if (isItReallyPng(secondPart)) {
                    return true;
                }

                LOG.debug("Looks like file isn't a PNG image. First bytes: {} {}", formatBytes(firstPart),
                        formatBytes(secondPart));
                return false;
            }

            LOG.debug("Looks like file isn't an image. First bytes: {}", formatBytes(firstPart));
            return false;

        } catch (IOException e) {
            LOG.warn("Error during file type validation: {}", e.getMessage());
            return false;
        }
    }

}