Use html.escape to replace _quote_html in http.server

[zhangyangyu]

BPO	26585
Nosy	@vadmium, @zhangyangyu
Dependencies	bpo-26609: Wrong request target in test_httpservers.py
Files	_quote_html_to_html_escape.patch: Use html.escape to replace _quote_html for BaseHTTPRequestHandler _quote_html_to_html_escape_v2.patch _quote_html_to_html_escape_v3.patch _quote_html_to_html_escape_v4.patch _quote_html_to_html_escape_v5.patch

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = <Date 2016-04-11.04:04:32.670>
created_at = <Date 2016-03-18.03:18:06.756>
labels = ['type-feature', 'library']
title = 'Use html.escape to replace _quote_html in http.server'
updated_at = <Date 2016-04-11.07:15:56.590>
user = 'https://github.com/zhangyangyu'

bugs.python.org fields:

activity = <Date 2016-04-11.07:15:56.590>
actor = 'xiang.zhang'
assignee = 'none'
closed = True
closed_date = <Date 2016-04-11.04:04:32.670>
closer = 'martin.panter'
components = ['Library (Lib)']
creation = <Date 2016-03-18.03:18:06.756>
creator = 'xiang.zhang'
dependencies = ['26609']
files = ['42195', '42204', '42205', '42218', '42220']
hgrepos = []
issue_num = 26585
keywords = ['patch']
message_count = 17.0
messages = ['261943', '261944', '261950', '261951', '261975', '261978', '262001', '262018', '262021', '262040', '262041', '262057', '262062', '262814', '263159', '263164', '263170']
nosy_count = 3.0
nosy_names = ['python-dev', 'martin.panter', 'xiang.zhang']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue26585'
versions = ['Python 3.6']

[zhangyangyu]

In http.server, _quote_html is used to escape content for BaseHTTPServer. The function has already been implemented by html.escape.

[zhangyangyu]

It's BaseHTTPRequestHandler, not BaseHTTPServer.

[vadmium]

Removing the redundant _quote_html() function seems like a good idea to me. I wonder if the code should be using the html.escape(..., quote=False) option though, because it does not need to encode quote signs.

It might be good to add a test. It looks like there may not be anything testing the HTML encoding.

[zhangyangyu]

At first I also want to use html.escape(..., quote=False) since the spec only asks to escape quote signs in attribute. But after some search on Google, there are articles recommends escaping quote in content too: https://www.owasp.org/index.php/XSS_%28Cross_Site_Scripting%29_Prevention_Cheat_Sheet

[zhangyangyu]

I add two tests for html escaping. One for the error message and the other for display name in SimpleHTTPRequesthandler.

[zhangyangyu]

make some change to test for html escape in SimpleHTTPRequestHandler

[vadmium]

Thanks for the tests. I left a couple comments.

About encoding quotes: Personally I don’t see much value unless you are encoding an attribute value, in which case I would prefer to use xml.sax.saxutils.quoteattr(). Encoded quotes would only become useful if the “error_message_format” attribute was modified.

A more practical downside is that if “error_content_type” is set to say text/plain, we are adding two somewhat common characters that will get messed up. E.g. the “explain” string for 429 Too Many Requests will include the double-quoted "rate limiting". And an apostrophe could easily be given in a custom error message, e.g. “Can't write a clean error message”.

[zhangyangyu]

Thanks for your review. Set quote to False when html.escape is OK to me. But except for the usage in BaseHTTPRequestHandler, I think we should also set quote to False for the usage in SimpleHTTPRequestHandler since they do not appear in attribute either. And I left a reply to your comment. How do you think about these?

[vadmium]

Yeah I would be happy if you want to change to html.escape(quote=False) in list_directory() as well.

BTW I am getting Undelivered Mail replies from the review comments. I guess they might be getting rejected due to looking like spam (they tend to be classified as spam by default for me, something about how the server sends them).

[zhangyangyu]

OK. You left the comment preferring using ascii or utf-8 to encode the filename in test. But actually the response SimpeHTTPRequestHandler send is explicitly encoded in filesystemdefaultencoding. So in such a case, am I doing right?

[zhangyangyu]

Oops. You have already left new comment. No notify either. :(

I like the idea that extract the actual encoding from response header. I will update my patch then.

[zhangyangyu]

The uploaded patch is updated. Hope you have time to review.

[zhangyangyu]

Thanks for the reviews. I have updated the patch.