Files @ aa51aca7fd1a
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Location: kallithea/scripts/pyflakes - annotation

Valentin Kleibel
controller: Handle UnicodeDecodeError from webob decoding invalid URLs

webob will try to utf-8 decode all %-encoded bytes in URL-parameters, but will
not handle Unicode erors ... and neither did Kallithea. Visiting a URL like
http://localhost:5000/?%AD would thus give an unhandled exception showing
"Internal Server Error" to the user, and logging the full traceback and:

WebApp Error: UnicodeDecodeError: 'utf-8' codec can't decode byte 0xad in position 0: invalid start byte

This has been seen a lot recently from attackers probing for a php
vulnerability
https://devco.re/blog/2024/06/06/security-alert-cve-2024-4577-php-cgi-argument-injection-vulnerability-en/ .

Now handle these exceptions more nicely and reject with "400 Bad Request".
#!/usr/bin/env python3
"""
pyflakes with filter configuration for Kallithea.
Inspired by pyflakes/api.py and flake8/plugins/pyflakes.py .
"""

import sys

import pyflakes.api
import pyflakes.messages


class Reporter:

    warned = False

    def flake(self, warning):
        # ignore known warnings
        if isinstance(warning, pyflakes.messages.UnusedVariable):
            return
        if warning.filename == 'kallithea/bin/kallithea_cli_ishell.py':
            if isinstance(warning, pyflakes.messages.ImportStarUsed) and warning.message_args == ('kallithea.model.db',):
                return
            if isinstance(warning, pyflakes.messages.UnusedImport) and warning.message_args == ('kallithea.model.db.*',):
                return

        print('%s:%s %s   [%s %s]' % (warning.filename, warning.lineno, warning.message % warning.message_args, type(warning).__name__, warning.message_args))
        self.warned = True

    def unexpectedError(self, filename, msg):
        print('Unexpected error for %s: %s' % (filename, msg))


reporter = Reporter()

for filename in sorted(set(sys.argv[1:])):
    pyflakes.api.checkPath(filename, reporter=reporter)
if reporter.warned:
    raise SystemExit(1)