extract original content from chrome about:cache html source

extract_chrome_cache_html.py

import sys
import re
import gzip
import mimetypes
from mimetools import Message
from StringIO import StringIO

def parse_headers(raw_headers):
    response_line, headers_text = raw_headers.split('\n', 1)
    headers = Message(StringIO(headers_text))
    return dict(headers)

def filter_blank(lines):
    for line in lines:
        line = line.strip()
        if line != '':
            yield line

def convert_cache_line(cache_line):
    result = ''
    for byte in cache_line.split('  ')[1:17]:
        if byte == '':
            break
        result += chr(int(byte, 16))
    return result

def gzip_decompress(data):
    return gzip.GzipFile('', 'rb', 9, StringIO(data)).read()

def decode_cache_html(cache_html):
    pre_regexp = re.compile('<pre>(.*?)</pre>', re.DOTALL)
    matches = pre_regexp.findall(cache_html)

    raw_headers = matches[0]
    headers = parse_headers(raw_headers)

    segments = []
    for raw_content in filter_blank(matches[1:]):
        segment = ''
        for line in filter_blank(raw_content.split('\n')):
            if line != '':
                segment += convert_cache_line(line)
        segments.append(segment)

    return headers, segments

def main():
    for filename in sys.argv[1:]:
        with open(filename) as input_file:
            cache_html = input_file.read()
            headers, segments = decode_cache_html(cache_html)

            # segment[0] is usually the header + certificate
            data = segments[1]
            if headers.get('content-encoding') == 'gzip':
                data = gzip_decompress(data)

            content_type = headers['content-type'].split(';')[0]
            extension = mimetypes.guess_all_extensions(content_type)[0]

            output_filename = filename + '-decoded' + extension
            print 'writing to {0}'.format(output_filename)
            with open(output_filename, 'w') as output_file:
                output_file.write(data)

if __name__ == "__main__":
    main()