mailinabox/tools/update-subresource-integrit...

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#!/usr/bin/python3
# Updates subresource integrity attributes in management/templates/index.html
# to prevent CDN-hosted resources from being used as an attack vector. Run this
# after updating the Bootstrap and jQuery <link> and <script> to compute the
# appropriate hash and insert it into the template.
import re, urllib.request, hashlib, base64
fn = "management/templates/index.html"
with open(fn, 'r') as f:
content = f.read()
def make_integrity(url):
resource = urllib.request.urlopen(url).read()
return "sha256-" + base64.b64encode(hashlib.sha256(resource).digest()).decode('ascii')
content = re.sub(
r'<(link rel="stylesheet" href|script src)="(.*?)" integrity="(.*?)"',
lambda m : '<' + m.group(1) + '="' + m.group(2) + '" integrity="' + make_integrity(m.group(2)) + '"',
content)
with open(fn, 'w') as f:
f.write(content)