Provide means to reject malicious or large images which can lead to denial-of-service

[coobird]

Highly-compressed images in the form of large PNGs or malicious PNG decompression bombs could lead to OutOfMemoryErrors.

While I haven't researched whether decompression bombs can actually happen with the default PNG reader bundled with Java, if such things can happen, then a countermeasure against them would be nice to incorporate in Thumbnailator.

Also, OOMs from large images could be avoided by first checking the dimensions of the image.

If a image is rejected, it may be useful to return the images which failed via a callback mechanism. (Perhaps something like a RejectedImageListener that is given via one of the top-level API method, which enables this feature.)

References:

• Defending Libpng Applications Against Decompression Bombs
• The Java Image Processing Survival Guide - Memory Usage
• How to check png file if it's a decompression bomb