oauth_dropins.webutil

Reference documentation.

flask_util

Utilities for Flask. View classes, decorators, URL route converters, etc.

exception oauth_dropins.webutil.flask_util.Created(description: Optional[str] = None, response: Optional[Response] = None)[source]

Bases: werkzeug.exceptions.HTTPException

exception oauth_dropins.webutil.flask_util.Accepted(description: Optional[str] = None, response: Optional[Response] = None)[source]

Bases: werkzeug.exceptions.HTTPException

exception oauth_dropins.webutil.flask_util.NoContent(description: Optional[str] = None, response: Optional[Response] = None)[source]

Bases: werkzeug.exceptions.HTTPException

exception oauth_dropins.webutil.flask_util.NotModified(description: Optional[str] = None, response: Optional[Response] = None)[source]

Bases: werkzeug.exceptions.HTTPException

exception oauth_dropins.webutil.flask_util.PaymentRequired(description: Optional[str] = None, response: Optional[Response] = None)[source]

Bases: werkzeug.exceptions.HTTPException

exception oauth_dropins.webutil.flask_util.ProxyAuthenticationRequired(description: Optional[str] = None, response: Optional[Response] = None)[source]

Bases: werkzeug.exceptions.HTTPException

exception oauth_dropins.webutil.flask_util.MisdirectedRequest(description: Optional[str] = None, response: Optional[Response] = None)[source]

Bases: werkzeug.exceptions.HTTPException

exception oauth_dropins.webutil.flask_util.UpgradeRequired(description: Optional[str] = None, response: Optional[Response] = None)[source]

Bases: werkzeug.exceptions.HTTPException

exception oauth_dropins.webutil.flask_util.PreconditionRequired(description: Optional[str] = None, response: Optional[Response] = None)[source]

Bases: werkzeug.exceptions.HTTPException

exception oauth_dropins.webutil.flask_util.ClientClosedRequest(description: Optional[str] = None, response: Optional[Response] = None)[source]

Bases: werkzeug.exceptions.HTTPException

exception oauth_dropins.webutil.flask_util.VariantAlsoNegotiates(description: Optional[str] = None, response: Optional[Response] = None)[source]

Bases: werkzeug.exceptions.HTTPException

exception oauth_dropins.webutil.flask_util.InsufficientStorage(description: Optional[str] = None, response: Optional[Response] = None)[source]

Bases: werkzeug.exceptions.HTTPException

exception oauth_dropins.webutil.flask_util.LoopDetected(description: Optional[str] = None, response: Optional[Response] = None)[source]

Bases: werkzeug.exceptions.HTTPException

exception oauth_dropins.webutil.flask_util.NotExtended(description: Optional[str] = None, response: Optional[Response] = None)[source]

Bases: werkzeug.exceptions.HTTPException

exception oauth_dropins.webutil.flask_util.NetworkAuthenticationRequired(description: Optional[str] = None, response: Optional[Response] = None)[source]

Bases: werkzeug.exceptions.HTTPException

exception oauth_dropins.webutil.flask_util.NetworkConnectTimeoutError(description: Optional[str] = None, response: Optional[Response] = None)[source]

Bases: werkzeug.exceptions.HTTPException

class oauth_dropins.webutil.flask_util.RegexConverter(url_map, *items)[source]

Bases: werkzeug.routing.BaseConverter

Regexp URL route for Werkzeug/Flask.

Based on https://github.com/rhyselsmore/flask-reggie.

Usage:

@app.route(‘/<regex(“(abc|def)”):letters>’)

Install with:

app = Flask(…) app.url_map.converters[‘regex’] = RegexConverter

oauth_dropins.webutil.flask_util.get_required_param(name)[source]

Returns the given request parameter.

If it’s not in a query parameter or POST field, the current HTTP request aborts with status 400.

oauth_dropins.webutil.flask_util.ndb_context_middleware(app, client=None)[source]

WSGI middleware to add an NDB context per request.

Follows the WSGI standard. Details: http://www.python.org/dev/peps/pep-0333/

Install with e.g.:

ndb_client = ndb.Client() app = Flask(‘my-app’) app.wsgi_app = flask_util.ndb_context_middleware(app.wsgi_app, ndb_client)

Background: https://cloud.google.com/appengine/docs/standard/python3/migrating-to-cloud-ndb#using_a_runtime_context_with_wsgi_frameworks

Parameters

clientgoogle.cloud.ndb.Client

oauth_dropins.webutil.flask_util.handle_exception(e)[source]

Flask error handler that propagates HTTP exceptions into the response.

Install with:

app.register_error_handler(Exception, handle_exception)

oauth_dropins.webutil.flask_util.error(msg, status=400, exc_info=False, **kwargs)[source]

Logs and returns an HTTP error via werkzeug.exceptions.HTTPException.

Parameters
  • msg – str

  • status – int

  • exc_info – Python exception info three-tuple, eg from sys.exc_info()

  • kwargs – passed through to flask.abort()

oauth_dropins.webutil.flask_util.default_modern_headers(resp)[source]

Include modern HTTP headers by default, but let the response override them.

Install with:

app.after_request(default_modern_headers)

oauth_dropins.webutil.flask_util.cached(cache, timeout, http_5xx=False)[source]

Thin flask-cache wrapper that supports timedelta and cache query param.

If the cache URL query parameter is false, skips the cache. Also, does not store the response in the cache if it’s an HTTP 5xx or if there are any flashed messages.

Parameters
oauth_dropins.webutil.flask_util.canonicalize_domain(from_domains, to_domain)[source]

Returns a callable that redirects one or more domains to a canonical domain.

Preserves scheme, path, and query.

Install with eg:

app = flask.Flask(…) app.before_request(canonicalize_domain((‘old1.com’, ‘old2.org’), ‘new.com’))

Parameters
  • from_domains – str or sequence of str

  • to_domain – str

class oauth_dropins.webutil.flask_util.XrdOrJrd[source]

Bases: flask.views.View

Renders and serves an XRD or JRD file.

JRD is served if the request path ends in .jrd or .json, or the format query parameter is ‘jrd’ or ‘json’, or the request’s Accept header includes ‘jrd’ or ‘json’.

XRD is served if the request path ends in .xrd or .xml, or the format query parameter is ‘xml’ or ‘xrd’, or the request’s Accept header includes ‘xml’ or ‘xrd’.

Otherwise, defaults to DEFAULT_TYPE.

Subclasses must override template_prefix() and template_vars(). URL route variables are passed through to template_vars() as keyword args.

Class members:

DEFAULT_TYPE: either JRD or XRD, which type to return by default if the request doesn’t ask for one explicitly with the Accept header.

template_prefix()[source]

Returns template filename, without extension.

template_vars(**kwargs)[source]

Returns a dict with template variables.

URL route variables are passed through as kwargs.

dispatch_request(**kwargs)[source]

Subclasses have to override this method to implement the actual view function code. This method is called with all the arguments from the URL rule.

oauth_dropins.webutil.flask_util.cls

alias of oauth_dropins.webutil.flask_util.NetworkConnectTimeoutError

handlers

Request handler utility classes.

Includes classes for serving templates with common variables and XRD[S] and JRD files like host-meta and friends.

oauth_dropins.webutil.handlers.handle_exception(self, e, debug)[source]

A webapp2 exception handler that propagates HTTP exceptions into the response.

Use this as a webapp2.RequestHandler.handle_exception() method by adding this line to your handler class definition:

handle_exception = handlers.handle_exception
oauth_dropins.webutil.handlers.redirect(from_domains, to_domain)[source]

webapp2.RequestHandler decorator that 301 redirects to a new domain.

Preserves scheme, path, and query.

Parameters
  • from_domain – string or sequence of strings

  • to_domain – strings

oauth_dropins.webutil.handlers.cache_response(expiration, size=20000000, headers=None)[source]

webapp2.RequestHandler method decorator that caches the response in memory.

Includes a cache_clear() function that clears all cached responses.

Ideally this would be just a thin wrapper around the cachetools.cachedmethod() decorator, but that doesn’t pass self to the key function, which we need to get the request URL. Long discussion: https://github.com/tkem/cachetools/issues/107

Parameters
  • expirationdatetime.timedelta

  • size – integer, bytes. defaults to 20 MB.

  • headers – sequencey of string HTTP headers to include in the cache key

oauth_dropins.webutil.handlers.throttle(one_request_each, cache_size=5000)[source]

webapp2.RequestHandler method decorator that rate limits requests.

Accepts at most one request with a given URL (including query parameters) within each one_request_each time period. After that, serves a HTTP 429 response to each subsequent request for the same URL until the time period finished.

Parameters
  • one_request_eachdatetime.timedelta

  • cache_size – integer, number of URLs to cache. defaults to 5000.

oauth_dropins.webutil.handlers.ndb_context_middleware(app, client=None)[source]

WSGI middleware to add an NDB context per request.

Follows the WSGI standard. Details: http://www.python.org/dev/peps/pep-0333/

Install with e.g.:

application = handlers.ndb_context_middleware(webapp2.WSGIApplication(…)

Background: https://cloud.google.com/appengine/docs/standard/python3/migrating-to-cloud-ndb#using_a_runtime_context_with_wsgi_frameworks

Parameters

clientgoogle.cloud.ndb.Client

class oauth_dropins.webutil.handlers.ModernHandler(*args, **kwargs)[source]

Bases: webapp2.RequestHandler

Base handler that adds modern open/secure headers like CORS, HSTS, etc.

handle_exception(e, debug)

A webapp2 exception handler that propagates HTTP exceptions into the response.

Use this as a webapp2.RequestHandler.handle_exception() method by adding this line to your handler class definition:

handle_exception = handlers.handle_exception
options(*args, **kwargs)[source]

Respond to CORS pre-flight OPTIONS requests.

class oauth_dropins.webutil.handlers.TemplateHandler(*args, **kwargs)[source]

Bases: oauth_dropins.webutil.handlers.ModernHandler

Renders and serves a template based on class attributes.

Subclasses must override template_file() and may also override template_vars() and content_type().

template_file()[source]

Returns the string template file path.

template_vars(*args, **kwargs)[source]

Returns a dict of template variable string keys and values.

Parameters
  • args – passed through from get()

  • kwargs – passed through from get()

content_type()[source]

Returns the string content type.

headers()[source]

Returns dict of HTTP response headers. Subclasses may override.

To advertise XRDS, use:

headers['X-XRDS-Location'] = 'https://%s/.well-known/host-meta.xrds' % self.request.host

instance_info

Renders vital stats about a single App Engine instance.

Intended for developers, not users. To turn on concurrent request recording, add the middleware and InfoHandler to your WSGI application, eg:

from oauth_dropins.webutil.instance_info import concurrent_requests_wsgi_middleware, InfoHandler

application = concurrent_requests_wsgi_middleware(webapp2.WSGIApplication([

… (‘/_info’, InfoHandler),

])

class oauth_dropins.webutil.instance_info.Concurrent(count, when)

Bases: tuple

property count

Alias for field number 0

property when

Alias for field number 1

class oauth_dropins.webutil.instance_info.InfoHandler(*args, **kwargs)[source]

Bases: oauth_dropins.webutil.handlers.TemplateHandler

template_file()[source]

Returns the string template file path.

template_vars()[source]

Returns a dict of template variable string keys and values.

Parameters
  • args – passed through from get()

  • kwargs – passed through from get()

oauth_dropins.webutil.instance_info.concurrent_requests_wsgi_middleware(app)[source]

WSGI middleware for per request instance info instrumentation.

Follows the WSGI standard. Details: http://www.python.org/dev/peps/pep-0333/

logs

A handler that serves all app logs for an App Engine HTTP request.

StackDriver Logging API: https://cloud.google.com/logging/docs/apis

oauth_dropins.webutil.logs.sanitize(msg)[source]

Sanitizes access tokens and Authorization headers.

oauth_dropins.webutil.logs.url(when, key)[source]

Returns the relative URL (no scheme or host) to a log page.

Parameters
  • when – datetime

  • key – ndb.Key

Returns an HTML snippet with a timestamp and maybe a log page link.

Example:

<a href=”/log?start_time=1513904267&key=aglz…” class=”u-bridgy-log”>
<time class=”dt-updated” datetime=”2017-12-22T00:57:47.222060”

title=”Fri Dec 22 00:57:47 2017”>

3 days ago

</time>

</a>

The <a> tag is only included if the timestamp is 30 days old or less, since Stackdriver’s basic tier doesn’t store logs older than that:

Parameters
  • when – datetime

  • key – ndb.Key

  • time_class – string, optional class value for the <time> tag

  • link_class – string, optional class value for the <a> tag (if generated)

Returns: string HTML

oauth_dropins.webutil.logs.linkify_datastore_keys(msg)[source]

Converts string datastore keys to links to the admin console viewer.

oauth_dropins.webutil.logs.utcfromtimestamp(val)[source]

Wrapper for datetime.utcfromtimestamp that returns HTTP 400 on overflow.

…specifically, if datetime.utcfromtimestamp raises OverflowError because the timestamp is greater than the platform’s time_t can hold. https://docs.python.org/3.9/library/datetime.html#datetime.datetime.utcfromtimestamp

oauth_dropins.webutil.logs.log()[source]

Flask view that searches for and renders app logs for an HTTP request.

URL parameters:

start_time: float, seconds since the epoch key: string that should appear in the first app log

Install with:

app.add_url_rule(‘/log’, view_func=logs.log)

Or:

@app.get(‘/log’) @cache.cached(600) def log():

return logs.log()

models

App Engine datastore model base classes and utilites.

class oauth_dropins.webutil.models.StringIdModel(**kwargs)[source]

Bases: google.cloud.ndb.model.Model

An ndb model class that requires a string id.

put(*args, **kwargs)[source]

Raises AssertionError if string id is not provided.

testutil

Unit test utilities.

oauth_dropins.webutil.testutil.requests_response(body='', url=None, status=200, content_type=None, redirected_url=None, headers=None, allow_redirects=None, encoding=None)[source]
Parameters

redirected_url – string URL or sequence of string URLs for multiple redirects

oauth_dropins.webutil.testutil.enable_flask_caching(app, cache)[source]

Test case decorator that enables a flask_caching cache.

Usage:

from app import app, cache

class FooTest(TestCase):

@enable_flask_caching(app, cache) def test_foo(self):

Parameters
class oauth_dropins.webutil.testutil.UrlopenResult(status_code, content, url=None, headers={})[source]

Bases: object

A fake urllib.request.urlopen() or urlfetch.fetch() result object.

class oauth_dropins.webutil.testutil.Asserts[source]

Bases: object

Test case mixin class with extra assert helpers.

assert_entities_equal(a, b, ignore=frozenset({}), keys_only=False, in_order=False)[source]

Asserts that a and b are equivalent entities or lists of entities.

…specifically, that they have the same property values, and if they both have populated keys, that their keys are equal too.

Parameters
  • andb.Model instances or lists of instances

  • b – same

  • ignore – sequence of strings, property names not to compare

  • keys_only – boolean, if True only compare keys

  • in_order – boolean. If False, all entities must have keys.

entity_keys(entities)[source]

Returns a list of keys for a list of entities.

assert_equals(expected, actual, msg=None, in_order=False)[source]

Pinpoints individual element differences in lists and dicts.

If in_order is False, ignores order in lists and tuples.

assert_multiline_equals(expected, actual, ignore_blanks=False)[source]

Compares two multi-line strings and reports a diff style output.

Ignores leading and trailing whitespace on each line, and squeezes repeated blank lines down to just one.

Parameters

ignore_blanks – boolean, whether to ignore blank lines altogether

assert_multiline_in(expected, actual, ignore_blanks=False)[source]

Checks that a multi-line string is in another and reports a diff output.

Ignores leading and trailing whitespace on each line, and squeezes repeated blank lines down to just one.

Parameters

ignore_blanks – boolean, whether to ignore blank lines altogether

class oauth_dropins.webutil.testutil.TestCase(methodName='runTest')[source]

Bases: mox3.mox.MoxTestBase, oauth_dropins.webutil.testutil.Asserts

Test case class with lots of extra helpers.

maxDiff = None
setUp()[source]

Hook method for setting up the test fixture before exercising it.

stub_requests_head()[source]

Automatically return 200 to outgoing HEAD requests.

unstub_requests_head()[source]

Mock outgoing HEAD requests so they must be expected individually.

expect_urlopen(url, response=None, status=200, data=None, headers=None, response_headers={}, **kwargs)[source]

Stubs out urllib.request.urlopen() and sets up an expected call.

If status isn’t 2xx, makes the expected call raise a urllib.error.HTTPError instead of returning the response.

If data is set, url must be a urllib.request.Request.

If response is unset, returns the expected call.

Parameters
  • url – string, re.RegexObject or urllib.request.Request or webob.request.Request

  • response – string

  • status – int, HTTP response code

  • data – optional string POST body

  • headers – optional expected request header dict

  • response_headers – optional response header dict

  • kwargs – other keyword args, e.g. timeout

class oauth_dropins.webutil.testutil.HandlerTest(methodName='runTest')[source]

Bases: oauth_dropins.webutil.testutil.TestCase

Base test class for webapp2 request handlers.

handler

webapp2.RequestHandler

request

webob.Request

response

webob.Response

setUp()[source]

Hook method for setting up the test fixture before exercising it.

util

Misc utilities.

Should not depend on App Engine API or SDK packages.

oauth_dropins.webutil.util.LOCAL_TLDS = {'local', 'localhost'}

Global config, string parser nae for BeautifulSoup to use, e.g. ‘lxml’. May be set at runtime. https://www.crummy.com/software/BeautifulSoup/bs4/doc/#installing-a-parser

class oauth_dropins.webutil.util.Struct(**kwargs)[source]

Bases: object

A generic class that initializes its attributes from constructor kwargs.

class oauth_dropins.webutil.util.CacheDict[source]

Bases: dict

A dict that also implements memcache’s get_multi() and set_multi() methods.

Useful as a simple in memory replacement for App Engine’s memcache API for e.g. get_activities_response() in granary.

oauth_dropins.webutil.util.to_xml(value)[source]

Renders a dict (usually from JSON) as an XML snippet.

oauth_dropins.webutil.util.trim_nulls(value, ignore=())[source]

Recursively removes dict and list elements with None or empty values.

Parameters
  • value – dict or list

  • ignore – optional sequence of keys to allow to have None/empty values

oauth_dropins.webutil.util.uniquify(input)[source]

Returns a list with duplicate items removed.

Like list(set(…)), but preserves order.

oauth_dropins.webutil.util.get_list(obj, key)[source]

Returns a value from a dict as a list.

If the value is a list or tuple, it’s converted to a list. If it’s something else, it’s returned as a single-element list. If the key doesn’t exist, returns [].

oauth_dropins.webutil.util.pop_list(obj, key)[source]

Like get_list(), but also removes the item.

oauth_dropins.webutil.util.encode(obj, encoding='utf-8')[source]

Character encodes all unicode strings in a collection, recursively.

Parameters
  • obj – list, tuple, dict, set, or primitive

  • encoding – string character encoding

Returns

sequence or dict version of obj with all unicode strings encoded

oauth_dropins.webutil.util.get_first(obj, key, default=None)[source]

Returns the first element of a dict value.

If the value is a list or tuple, returns the first value. If it’s something else, returns the value itself. If the key doesn’t exist, returns None.

oauth_dropins.webutil.util.get_url(val, key=None)[source]

Returns val[‘url’] if val is a dict, otherwise val.

If key is not None, looks in val[key] instead of val.

oauth_dropins.webutil.util.get_urls(obj, key, inner_key=None)[source]

Returns elem[‘url’] if dict, otherwise elem, for each elem in obj[key].

If inner_key is provided, the returned values are elem[inner_key][‘url’].

oauth_dropins.webutil.util.tag_uri(domain, name, year=None)[source]

Returns a tag URI string for the given domain and name.

Example return value: ‘tag:twitter.com,2012:snarfed_org/172417043893731329

Background on tag URIs: http://taguri.org/

oauth_dropins.webutil.util.parse_tag_uri(uri)[source]

Returns the domain and name in a tag URI string.

Inverse of tag_uri().

Returns

(string domain, string name) tuple, or None if the tag URI couldn’t be parsed

oauth_dropins.webutil.util.parse_acct_uri(uri, hosts=None)[source]

Parses acct: URIs of the form acct:user@example.com .

Background: http://hueniverse.com/2009/08/making-the-case-for-a-new-acct-uri-scheme/

Parameters
  • uri – string

  • hosts – sequence of allowed hosts (usually domains). None means allow all.

Returns

(username, host) tuple

Raises: ValueError if the uri is invalid or the host isn’t allowed.

Extracts and returns the meaningful domain from a URL.

Strips www., mobile., and m. from the beginning of the domain.

Parameters

url – string

Returns

string

oauth_dropins.webutil.util.domain_or_parent_in(input, domains)[source]

Returns True if an input domain or its parent is in a set of domains.

Examples:

  • foo, [] => False

  • foo, [foo] => True

  • foo.bar.com, [bar.com] => True

  • foobar.com, [bar.com] => False

  • foo.bar.com, [.bar.com] => True

  • foo.bar.com, [fux.bar.com] => False

  • bar.com, [fux.bar.com] => False

Parameters
  • input – string domain

  • domains – sequence of string domains

Returns

boolean

oauth_dropins.webutil.util.update_scheme(url, request)[source]

Returns a modified URL with the current request’s scheme.

Useful for converting URLs to https if and only if the current request itself is being served over https.

Parameters

Returns: string, url

oauth_dropins.webutil.util.schemeless(url, slashes=True)[source]

Strips the scheme (e.g. ‘https:’) from a URL.

Parameters
  • url – string

  • leading_slashes – if False, also strips leading slashes and trailing slash, e.g. ‘http://example.com/’ becomes ‘example.com’

Returns

string URL

oauth_dropins.webutil.util.fragmentless(url)[source]

Strips the fragment (e.g. ‘#foo’) from a URL.

Parameters

url – string

Returns

string URL

oauth_dropins.webutil.util.clean_url(url)[source]

Removes transient query params (e.g. utm_*) from a URL.

The utm_* (Urchin Tracking Metrics?) params come from Google Analytics. https://support.google.com/analytics/answer/1033867

The source=rss-… params are on all links in Medium’s RSS feeds.

Parameters

url – string

Returns

string, the cleaned url, or None if it can’t be parsed

oauth_dropins.webutil.util.quote_path(url)[source]

Quotes (URL-encodes) just the path part of a URL.

Parameters

url – string

Returns

string, the quoted url, or None if it can’t be parsed

oauth_dropins.webutil.util.base_url(url)[source]

Returns the base of a given URL.

For example, returns ‘http://site/posts/’ for ‘http://site/posts/123’.

Parameters

url – string

Returns a list of unique string URLs in the given text.

URLs in the returned list are in the order they first appear in the text.

Splits text into link and non-link text.

Parameters
  • text – string to linkify

  • skip_bare_cc_tlds – boolean, whether to skip links of the form [domain].[2-letter TLD] with no schema and no path

  • skip_html_links – boolean, whether to skip links in HTML <a> tags ( both href and text)

  • require_scheme – boolean, whether to require scheme (eg http:// )

Returns

a tuple containing two lists of strings, a list of links and list of non-link text. Roughly equivalent to the output of re.findall and re.split, with some post-processing.

oauth_dropins.webutil.util.linkify(text, pretty=False, skip_bare_cc_tlds=False, **kwargs)[source]

Adds HTML links to URLs in the given plain text.

For example: linkify('Hello http://tornadoweb.org!') would return ‘Hello <a href=”http://tornadoweb.org”>http://tornadoweb.org</a>!’

Ignores URLs that are inside HTML links, ie anchor tags that look like <a href=”…”> .

Parameters
  • text – string, input

  • pretty – if True, uses pretty_link() for link text

  • skip_bare_cc_tlds – boolean, whether to skip links of the form [domain].[2-letter TLD] with no schema and no path

Returns

string, linkified input

Renders a pretty, short HTML link to a URL.

If text is not provided, the link text is the URL without the leading http(s)://[www.], ellipsized at the end if necessary. URL escape characters and UTF-8 are decoded.

The default maximum length follow’s Twitter’s rules: full domain plus 15 characters of path (including leading slash).

Parameters
  • url – string

  • text – string, optional

  • keep_host – if False, remove the host from the link text

  • glyphicon – string glyphicon to render after the link text, if provided. Details: http://glyphicons.com/

  • attrs – dict of attributes => values to include in the a tag. optional

  • new_tab – boolean, include target=”_blank” if True

  • max_length – int, max link text length in characters. ellipsized beyond this.

Returns

unicode string HTML snippet with <a> tag

class oauth_dropins.webutil.util.SimpleTzinfo[source]

Bases: datetime.tzinfo

A simple, DST-unaware tzinfo subclass.

utcoffset(dt)[source]

datetime -> timedelta showing offset from UTC, negative values indicating West of UTC

dst(dt)[source]

datetime -> DST offset as timedelta positive east of UTC.

oauth_dropins.webutil.util.parse_iso8601(val)[source]

Parses an ISO 8601 or RFC 3339 date/time string and returns a datetime.

Time zone designator is optional. If present, the returned datetime will be time zone aware.

Parameters

val – string ISO 8601 or RFC 3339, e.g. ‘2012-07-23T05:54:49+00:00’

Returns

datetime

oauth_dropins.webutil.util.parse_iso8601_duration(input)[source]

Parses an ISO 8601 duration.

Note: converts months to 30 days each. (ISO 8601 doesn’t seem to define the number of days in a month. Background: https://stackoverflow.com/a/29458514/186123 )

Parameters

input – string ISO 8601 duration, e.g. ‘P3Y6M4DT12H30M5S’

https://en.wikipedia.org/wiki/ISO_8601#Durations

Returns

datetime.timedelta, or None if input cannot be parsed as an ISO

8601 duration

oauth_dropins.webutil.util.to_iso8601_duration(input)[source]

Converts a timedelta to an ISO 8601 duration.

Returns a fairly strict format: ‘PnMTnS’. Fractional seconds are silently dropped.

Parameters

inputdatetime.timedelta

https://en.wikipedia.org/wiki/ISO_8601#Durations

Returns

string ISO 8601 duration, e.g. ‘P3DT4S’

Raises: TypeError if delta is not a datetime.timedelta

oauth_dropins.webutil.util.maybe_iso8601_to_rfc3339(input)[source]

Tries to convert an ISO 8601 date/time string to RFC 3339.

The formats are similar, but not identical, eg. RFC 3339 includes a colon in the timezone offset at the end (+0000 instead of +00:00), but ISO 8601 doesn’t.

If the input can’t be parsed as ISO 8601, it’s silently returned, unchanged!

http://www.rfc-editor.org/rfc/rfc3339.txt

oauth_dropins.webutil.util.maybe_timestamp_to_rfc3339(input)[source]

Tries to convert a string or int UNIX timestamp to RFC 3339.

Assumes UNIX timestamps are always UTC. (They’re generally supposed to be.)

oauth_dropins.webutil.util.maybe_timestamp_to_iso8601(input)[source]

Tries to convert a string or int UNIX timestamp to ISO 8601.

Assumes UNIX timestamps are always UTC. (They’re generally supposed to be.)

oauth_dropins.webutil.util.to_utc_timestamp(input)[source]

Converts a datetime to a float POSIX timestamp (seconds since epoch).

oauth_dropins.webutil.util.as_utc(input)[source]

Converts a timezone-aware datetime to a naive UTC datetime.

If input is timezone-naive, it’s returned as is.

Doesn’t support DST!

oauth_dropins.webutil.util.ellipsize(str, words=14, chars=140)[source]

Truncates and ellipsizes str if it’s longer than words or chars.

Words are simply tokenized on whitespace, nothing smart.

oauth_dropins.webutil.util.add_query_params(url, params)[source]

Adds new query parameters to a URL. Encodes as UTF-8 and URL-safe.

Parameters
  • url – string URL or urllib.request.Request. May already have query parameters.

  • params – dict or list of (string key, string value) tuples. Keys may repeat.

Returns

string URL

oauth_dropins.webutil.util.remove_query_param(url, param)[source]

Removes query parameter(s) from a URL. Decodes URL escapes and UTF-8.

If the query parameter is not present in the URL, the URL is returned unchanged, and the returned value is None.

If the query parameter is present multiple times, only the last value is returned.

Parameters
  • url – string URL

  • param – string name of query parameter to remove

Returns

(string URL without the given param, string param value)

oauth_dropins.webutil.util.dedupe_urls(urls, key=None)[source]

Normalizes and de-dupes http(s) URLs.

Converts domain to lower case, adds trailing slash when path is empty, and ignores scheme (http vs https), preferring https. Preserves order. Removes Nones and blank strings.

Domains are case insensitive, even modern domains with Unicode/punycode characters:

http://unicode.org/faq/idn.html#6 https://tools.ietf.org/html/rfc4343#section-5

As examples, http://foo/ and https://FOO are considered duplicates, but http://foo/bar and http://foo/bar/ aren’t.

Background: https://en.wikipedia.org/wiki/URL_normalization

TODO: port to https://pypi.python.org/pypi/urlnorm

Parameters
  • urls – sequence of string URLs or dict objects with ‘url’ keys

  • key – if not None, an inner key to be dereferenced in a dict object before looking for the ‘url’ key

Returns

sequence of string URLs

oauth_dropins.webutil.util.encode_oauth_state(obj)[source]

The state parameter is passed to various source authorization endpoints and returned in a callback. This encodes a JSON object so that it can be safely included as a query string parameter.

Parameters

obj – a JSON-serializable dict

Returns

a string

oauth_dropins.webutil.util.decode_oauth_state(state)[source]

Decodes a state parameter encoded by encode_state_parameter().

Parameters

state – a string (JSON-serialized dict), or None

Returns: dict

oauth_dropins.webutil.util.if_changed(cache, updates, key, value)[source]

Returns a value if it’s different from the cached value, otherwise None.

Values that evaluate to False are considered equivalent to None, in order to save cache space.

If the values differ, updates[key] is set to value. You can use this to collect changes that should be made to the cache in batch. None values in updates mean that the corresponding key should be deleted.

Parameters
  • cache – any object with a get(key) method

  • updates – mapping (e.g. dict)

  • key – anything supported by cache

  • value – anything supported by cache

Returns

value or None

oauth_dropins.webutil.util.generate_secret()[source]

Generates a URL-safe random secret string.

Uses App Engine’s os.urandom(), which is designed to be cryptographically secure: http://code.google.com/p/googleappengine/issues/detail?id=1055

Parameters

bytes – integer, length of string to generate

Returns

random string

oauth_dropins.webutil.util.is_int(arg)[source]

Returns True if arg can be converted to an integer, False otherwise.

oauth_dropins.webutil.util.is_float(arg)[source]

Returns True if arg can be converted to a float, False otherwise.

oauth_dropins.webutil.util.is_base64(arg)[source]

Returns True if arg is a base64 encoded string, False otherwise.

oauth_dropins.webutil.util.sniff_json_or_form_encoded(value)[source]

Detects whether value is JSON or form-encoded, parses and returns it.

Parameters

value – string

Returns: dict if form-encoded; dict or list if JSON; otherwise string

oauth_dropins.webutil.util.interpret_http_exception(exception)[source]

Extracts the status code and response from different HTTP exception types.

Parameters

exception

an HTTP request exception. Supported types:

Returns

(string status code or None, string response body or None)

oauth_dropins.webutil.util.is_connection_failure(exception)[source]

Returns True if the given exception is a network connection failure.

…False otherwise.

class oauth_dropins.webutil.util.FileLimiter(file_obj, read_limit)[source]

Bases: object

A file object wrapper that reads up to a limit and then reports EOF.

From http://stackoverflow.com/a/29838711/186123 . Thanks SO!

oauth_dropins.webutil.util.read(filename)[source]

Returns the contents of filename, or None if it doesn’t exist.

oauth_dropins.webutil.util.load_file_lines(file)[source]

Reads lines from a file and returns them as a set.

Leading and trailing whitespace is trimmed. Blank lines and lines beginning with # (ie comments) are ignored.

Parameters

file – a file object or other iterable that returns lines

Returns

set of strings

oauth_dropins.webutil.util.json_loads(*args, **kwargs)[source]

Wrapper around json.loads() that centralizes our JSON handling.

oauth_dropins.webutil.util.json_dumps(*args, **kwargs)[source]

Wrapper around json.dumps() that centralizes our JSON handling.

oauth_dropins.webutil.util.urlopen(url_or_req, *args, **kwargs)[source]

Wraps urllib.request.urlopen() and logs the HTTP method and URL.

oauth_dropins.webutil.util.requests_fn(fn)[source]

Wraps requests.* and logs the HTTP method and URL.

Parameters
  • fn – ‘get’, ‘head’, or ‘post’

  • gateway – boolean, whether this is in a HTTP gateway request handler context. If True, errors will be raised as appropriate Flask HTTP exceptions. Malformed URLs result in werkzeug.exceptions.BadRequest (HTTP 400), connection failures and HTTP 4xx and 5xx result in werkzeug.exceptions.BadGateway (HTTP 502).

oauth_dropins.webutil.util.requests_post_with_redirects(url, *args, **kwargs)[source]

Make an HTTP POST, and follow redirects with POST instead of GET.

Violates the HTTP spec’s rule to follow POST redirects with GET. Yolo!

Parameters

url – string

Returns: requests.Response

Raises: TooManyRedirects

oauth_dropins.webutil.util.follow_redirects(url, **kwargs)[source]

Fetches a URL with HEAD, repeating if necessary to follow redirects.

Caches results for 1 day by default. To bypass the cache, use follow_redirects.__wrapped__(…).

Does not raise an exception if any of the HTTP requests fail, just returns the failed response. If you care, be sure to check the returned response’s status code!

Parameters
  • url – string

  • kwargs – passed to requests.head()

Returns

the requests.Response for the final request. The url attribute has the

final URL.

class oauth_dropins.webutil.util.UrlCanonicalizer(scheme='https', domain=None, subdomain=None, approve=None, reject=None, query=False, fragment=False, trailing_slash=False, redirects=True, headers=None)[source]

Bases: object

Converts URLs to their canonical form.

If an input URL matches approve or reject, it’s automatically approved as is without following redirects.

If we HEAD the URL to follow redirects and it returns 4xx or 5xx, we return None.

class oauth_dropins.webutil.util.WideUnicode(*args, **kwargs)[source]

Bases: str

String class with consistent indexing and len() on narrow and wide Python.

PEP 261 describes that Python 2 builds come in “narrow” and “wide” flavors. Wide is configured with –enable-unicode=ucs4, which represents Unicode high code points above the 16-bit Basic Multilingual Plane in unicode strings as single characters. This means that len(), indexing, and slices of unicode strings use Unicode code points consistently.

Narrow, on the other hand, represents high code points as “surrogate pairs” of 16-bit characters. This means that len(), indexing, and slicing unicode strings does not always correspond to Unicode code points.

Mac OS X, Windows, and older Linux distributions have narrow Python 2 builds, while many modern Linux distributions have wide builds, so this can cause platform-specific bugs, e.g. with many commonly used emoji.

Docs: https://www.python.org/dev/peps/pep-0261/ https://docs.python.org/2.7/library/codecs.html?highlight=ucs2#encodings-and-unicode http://www.unicode.org/glossary/#high_surrogate_code_point

Inspired by: http://stackoverflow.com/a/9934913

Related work: https://uniseg-python.readthedocs.io/ https://pypi.python.org/pypi/pytextseg https://github.com/LuminosoInsight/python-ftfy/ https://github.com/PythonCharmers/python-future/issues/116 https://dev.twitter.com/basics/counting-characters

On StackOverflow: http://stackoverflow.com/questions/1446347/how-to-find-out-if-python-is-compiled-with-ucs-2-or-ucs-4 http://stackoverflow.com/questions/12907022/python-getting-correct-string-length-when-it-contains-surrogate-pairs http://stackoverflow.com/questions/35404144/correctly-extract-emojis-from-a-unicode-string

oauth_dropins.webutil.util.parse_html(input, **kwargs)[source]

Parses an HTML string with BeautifulSoup.

Uses the HTML parser currently set in the beautifulsoup_parser global. http://www.crummy.com/software/BeautifulSoup/bs4/doc/#specifying-the-parser-to-use

We generally try to use the same parser and version in prod and locally, since we’ve been bit by at least one meaningful difference between lxml and e.g. html5lib: lxml includes the contents of <noscript> tags, html5lib omits them. https://github.com/snarfed/bridgy/issues/798#issuecomment-370508015

Specifically, projects like oauth-dropins, granary, and bridgy all use lxml explicitly.

Parameters
  • input – unicode HTML string or requests.Response

  • kwargs – passed through to bs4.BeautifulSoup constructor

Returns: bs4.BeautifulSoup

oauth_dropins.webutil.util.parse_mf2(input, url=None, id=None)[source]

Parses microformats2 out of HTML.

Currently uses mf2py.

Parameters
  • input – unicode HTML string, bs4.BeautifulSoup, or requests.Response

  • url – optional unicode string, URL of the input page, used as the base for relative URLs

  • id – string, optional id of specific element to extract and parse. defaults to the whole page.

Returns: dict, parsed mf2 data

oauth_dropins.webutil.util.fetch_mf2(url, get_fn=<function requests_fn.<locals>.call>, gateway=False, **kwargs)[source]

Fetches an HTML page over HTTP, parses it, and returns its microformats2.

Parameters
Returns: dict, parsed mf2 data. Includes the final URL of the parsed document

(after redirects) in the top-level url field.

webmention

Webmention endpoint discovery and sending.

Spec: https://webmention.net/draft/

class oauth_dropins.webutil.webmention.Endpoint(endpoint, response)

Bases: tuple

property endpoint

Alias for field number 0

property response

Alias for field number 1

oauth_dropins.webutil.webmention.discover(url, **requests_kwargs)[source]

Discovers a URL’s webmention endpoint.

Parameters
  • url – str

  • requests_kwargs – passed to requests.post()

Returns: Endpoint. If no endpoint is discovered, the endpoint attribute will be None.

Raises: ValueError on bad URL, requests.HTTPError on failure

oauth_dropins.webutil.webmention.send(endpoint, source, target, **requests_kwargs)[source]

Sends a webmention.

Parameters
  • endpoint – str, webmention endpoint URL

  • source – str, source URL

  • target – str, target URL

  • requests_kwargs – passed to requests.post()

Returns: requests.Response on success.

Raises: ValueError on bad URL, requests.HTTPError on failure