Helpers — urllib3 1.16 documentation

# Helpers

Useful methods for working with `httplib`, completely decoupled from code specific to urllib3.

## Timeouts

class `urllib3.util.timeout.` `Timeout`(total=None, connect=<object object>, read=<object object>)

  Timeout configuration.

  Timeouts can be defined as a default for a pool:

      timeout = Timeout(connect=2.0, read=7.0)
      http = PoolManager(timeout=timeout)
      response = http.request('GET', 'http://example.com/')

  Or per-request (which overrides the default for the pool):

      response = http.request('GET', 'http://example.com/', timeout=Timeout(10))

  Timeouts can be disabled by setting all the parameters to `None`:

      no_timeout = Timeout(connect=None, read=None)
      response = http.request('GET', 'http://example.com/, timeout=no_timeout)

  Parameters: | total (integer, float, or None) – This combines the connect and read timeouts into one; the read timeout will be set to the time leftover from the connect attempt. In the event that both a connect timeout and a total are specified, or a read timeout and a total are specified, the shorter timeout will be applied. Defaults to None. connect (integer, float, or None) – The maximum amount of time to wait for a connection attempt to a server to succeed. Omitting the parameter will default the connect timeout to the system default, probably the global default timeout in socket.py. None will set an infinite timeout for connection attempts. read (integer, float, or None) – The maximum amount of time to wait between consecutive read operations for a response from the server. Omitting the parameter will default the read timeout to the system default, probably the global default timeout in socket.py. None will set an infinite timeout.

  Note

  Many factors can affect the total amount of time for urllib3 to return an HTTP response.

  For example, Python’s DNS resolver does not obey the timeout specified on the socket. Other factors that can affect total request time include high CPU load, high swap, the program running at a low priority level, or other behaviors.

  In addition, the read and total timeouts only measure the time between read operations on the socket connecting the client and the server, not the total amount of time for the request to return a complete response. For most requests, the timeout is raised because the server has not sent the first byte in the specified time. This is not always the case; if a server streams one byte every fifteen seconds, a timeout of 20 seconds will not trigger, even though the request will take several minutes to complete.

  If your goal is to cut off any request after a set amount of wall clock time, consider having a second “watcher” thread to cut off a slow request.

  `DEFAULT_TIMEOUT` = <object object>

    A sentinel object representing the default timeout value

  `clone`()

    Create a copy of the timeout object

    Timeout properties are stored per-pool but each request needs a fresh Timeout object to ensure each one has its own start/stop configured.

    Returns: | a copy of the timeout object
    Return type: | `Timeout`

  `connect_timeout`

    Get the value to use when setting a connection timeout.

    This will be a positive float or integer, the value None (never timeout), or the default system timeout.

    Returns: | Connect timeout.
    Return type: | int, float, `Timeout.DEFAULT_TIMEOUT` or None

  classmethod `from_float`(timeout)

    Create a new Timeout from a legacy timeout value.

    The timeout value used by httplib.py sets the same timeout on the connect(), and recv() socket requests. This creates a `Timeout` object that sets the individual timeouts to the `timeout` value passed to this function.

    Parameters: | timeout (integer, float, sentinel default object, or None) – The legacy timeout value.
    Returns: | Timeout object
    Return type: | `Timeout`

  `get_connect_duration`()

    Gets the time elapsed since the call to `start_connect()`.

    Returns: | Elapsed time.
    Return type: | float
    Raises: | urllib3.exceptions.TimeoutStateError – if you attempt to get duration for a timer that hasn’t been started.

  `read_timeout`

    Get the value for the read timeout.

    This assumes some time has elapsed in the connection timeout and computes the read timeout appropriately.

    If self.total is set, the read timeout is dependent on the amount of time taken by the connect timeout. If the connection time has not been established, a `TimeoutStateError` will be raised.

    Returns: | Value to use for the read timeout.
    Return type: | int, float, `Timeout.DEFAULT_TIMEOUT` or None
    Raises: | urllib3.exceptions.TimeoutStateError – If `start_connect()` has not yet been called on this object.

  `start_connect`()

    Start the timeout clock, used during a connect() attempt

    Raises: | urllib3.exceptions.TimeoutStateError – if you attempt to start a timer that has been started already.

`urllib3.util.timeout.` `current_time`()

  Retrieve the current time. This function is mocked out in unit testing.

## Retries

class `urllib3.util.retry.` `Retry`(total=10, connect=None, read=None, redirect=None, method_whitelist=frozenset(['HEAD', 'TRACE', 'GET', 'PUT', 'OPTIONS', 'DELETE']), status_forcelist=None, backoff_factor=0, raise_on_redirect=True, raise_on_status=True, _observed_errors=0)

  Retry configuration.

  Each retry attempt will create a new Retry object with updated values, so they can be safely reused.

  Retries can be defined as a default for a pool:

      retries = Retry(connect=5, read=2, redirect=5)
      http = PoolManager(retries=retries)
      response = http.request('GET', 'http://example.com/')

  Or per-request (which overrides the default for the pool):

      response = http.request('GET', 'http://example.com/', retries=Retry(10))

  Retries can be disabled by passing `False`:

      response = http.request('GET', 'http://example.com/', retries=False)

  Errors will be wrapped in `MaxRetryError` unless retries are disabled, in which case the causing exception will be raised.

  - Parameters: | total (int) – Total number of retries to allow. Takes precedence over other counts. Set to `None` to remove this constraint and fall back on other counts. It’s a good idea to set this to some sensibly-high value to account for unexpected edge cases and avoid infinite retry loops. Set to `0` to fail on the first retry. Set to `False` to disable and imply `raise_on_redirect=False`. connect (int) – How many connection-related errors to retry on. These are errors raised before the request is sent to the remote server, which we assume has not triggered the server to process the request. Set to `0` to fail on the first retry of this type. read (int) – How many times to retry on read errors. These errors are raised after the request was sent to the server, so the request may have side-effects. Set to `0` to fail on the first retry of this type. redirect (int) – How many redirects to perform. Limit this to avoid infinite redirect loops. A redirect is a HTTP response with a status code 301, 302, 303, 307 or 308. Set to `0` to fail on the first retry of this type. Set to `False` to disable and imply `raise_on_redirect=False`. method_whitelist (iterable) – Set of uppercased HTTP method verbs that we should retry on. By default, we only retry on methods which are considered to be idempotent (multiple requests with the same parameters end with the same state). See `Retry.DEFAULT_METHOD_WHITELIST`. Set to a `False` value to retry on any verb. status_forcelist (iterable) – A set of integer HTTP status codes that we should force a retry on. A retry is initiated if the request method is in `method_whitelist` and the response status code is in `status_forcelist`. By default, this is disabled with `None`. backoff_factor (float) – A backoff factor to apply between attempts after the second try (most errors are resolved immediately by a second try without a delay). urllib3 will sleep for:
        {backoff factor} * (2 ^ ({number of total retries} - 1))
  seconds. If the backoff_factor is 0.1, then `sleep()` will sleep for [0.0s, 0.2s, 0.4s, ...] between retries. It will never be longer than `Retry.BACKOFF_MAX`. By default, backoff is disabled (set to 0). raise_on_redirect (bool) – Whether, if the number of redirects is exhausted, to raise a MaxRetryError, or to return a response with a response code in the 3xx range. raise_on_status (bool) – Similar meaning to `raise_on_redirect`: whether we should raise an exception, or return a response, if status falls in `status_forcelist` range and retries have been exhausted.

  `BACKOFF_MAX` = 120

    Maximum backoff time.

  classmethod `from_int`(retries, redirect=True, default=None)

    Backwards-compatibility for the old retries format.

  `get_backoff_time`()

    Formula for computing the current backoff

    Return type: | float

  `increment`(method=None, url=None, response=None, error=None, _pool=None, _stacktrace=None)

    Return a new Retry object with incremented retry counters.

    Parameters: | response (`HTTPResponse`) – A response object, or None, if the server did not return a response. error (Exception) – An error encountered during the request, or None if the response was received successfully.
    Returns: | A new `Retry` object.

  `is_exhausted`()

    Are we out of retries?

  `is_forced_retry`(method, status_code)

    Is this method/status code retryable? (Based on method/codes whitelists)

  `sleep`()

    Sleep between retry attempts using an exponential backoff.

    By default, the backoff factor is 0 and this method will return immediately.

## URL Helpers

class `urllib3.util.url.` `Url`

  Datastructure for representing an HTTP URL. Used as a return value for `parse_url()`.

  `hostname`

    For backwards-compatibility with urlparse. We’re nice like that.

  `netloc`

    Network location including host and port

  `request_uri`

    Absolute path including the query string.

  `url`

    Convert self into a url

    This function should more or less round-trip with `parse_url()`. The returned url may not be exactly the same as the url inputted to `parse_url()`, but it should be equivalent by the RFC (e.g., urls with a blank port will have : removed).

    Example:

        >>> U = parse_url('http://google.com/mail/')
        >>> U.url
        'http://google.com/mail/'
        >>> Url('http', 'username:password', 'host.com', 80,
        ... '/path', 'query', 'fragment').url
        'http://username:password@host.com:80/path?query#fragment'

`urllib3.util.url.` `get_host`(url)

  Deprecated. Use `parse_url()` instead.

`urllib3.util.url.` `parse_url`(url)

  Given a url, return a parsed `Url` namedtuple. Best-effort is performed to parse incomplete urls. Fields not provided will be None.

  Partly backwards-compatible with `urlparse`.

  Example:

      >>> parse_url('http://google.com/mail/')
      Url(scheme='http', host='google.com', port=None, path='/mail/', ...)
      >>> parse_url('google.com:80')
      Url(scheme=None, host='google.com', port=80, path=None, ...)
      >>> parse_url('/foo?bar')
      Url(scheme=None, host=None, port=None, path='/foo', query='bar', ...)

`urllib3.util.url.` `split_first`(s, delims)

  Given a string and an iterable of delimiters, split on the first found delimiter. Return two split parts and the matched delimiter.

  If not found, then the first part is the full input string.

  Example:

      >>> split_first('foo/bar?baz', '?/=')
      ('foo', 'bar?baz', '/')
      >>> split_first('foo/bar?baz', '123')
      ('foo/bar?baz', '', None)

  Scales linearly with number of delims. Not ideal for large number of delims.

## Filepost

`urllib3.filepost.` `choose_boundary`()

  Our embarassingly-simple replacement for mimetools.choose_boundary.

`urllib3.filepost.` `encode_multipart_formdata`(fields, boundary=None)

  Encode a dictionary of `fields` using the multipart/form-data MIME format.

  Parameters: | fields – Dictionary of fields or list of (key, `RequestField`). boundary – If not specified, then a random boundary will be generated using `mimetools.choose_boundary()`.

`urllib3.filepost.` `iter_field_objects`(fields)

  Iterate over fields.

  Supports list of (k, v) tuples and dicts, and lists of `RequestField`.

`urllib3.filepost.` `iter_fields`(fields)

  Deprecated since version 1.6.

  Iterate over fields.

  The addition of `RequestField` makes this function obsolete. Instead, use `iter_field_objects()`, which returns `RequestField` objects.

  Supports list of (k, v) tuples and dicts.

class `urllib3.fields.` `RequestField`(name, data, filename=None, headers=None)

  A data container for request body parameters.

  Parameters: | name – The name of this request field. data – The data/value body. filename – An optional filename of the request field. headers – An optional dict-like object of headers to initially use for the field.

  classmethod `from_tuples`(fieldname, value)

    A `RequestField` factory from old-style tuple parameters.

    Supports constructing `RequestField` from parameter of key/value strings AND key/filetuple. A filetuple is a (filename, data, MIME type) tuple where the MIME type is optional. For example:

        'foo': 'bar',
        'fakefile': ('foofile.txt', 'contents of foofile'),
        'realfile': ('barfile.txt', open('realfile').read()),
        'typedfile': ('bazfile.bin', open('bazfile').read(), 'image/jpeg'),
        'nonamefile': 'contents of nonamefile field',

    Field names and filenames must be unicode.

  `make_multipart`(content_disposition=None, content_type=None, content_location=None)

    Makes this request field into a multipart request field.

    This method overrides “Content-Disposition”, “Content-Type” and “Content-Location” headers to the request parameter.

    Parameters: | content_type – The ‘Content-Type’ of the request body. content_location – The ‘Content-Location’ of the request body.

  `render_headers`()

    Renders the headers for this request field.

`urllib3.fields.` `format_header_param`(name, value)

  Helper function to format and quote a single header parameter.

  Particularly useful for header parameters which might contain non-ASCII values, like file names. This follows RFC 2231, as suggested by RFC 2388 Section 4.4.

  Parameters: | name – The name of the parameter, a string expected to be ASCII only. value – The value of the parameter, provided as a unicode string.

`urllib3.fields.` `guess_content_type`(filename, default='application/octet-stream')

  Guess the “Content-Type” of a file.

  Parameters: | filename – The filename to guess the “Content-Type” of using `mimetypes`. default – If no “Content-Type” can be guessed, default to default.

## Request

class `urllib3.request.` `RequestMethods`(headers=None)

  Convenience mixin for classes who implement a `urlopen()` method, such as `HTTPConnectionPool` and `PoolManager`.

  Provides behavior for making common types of HTTP request methods and decides which type of request field encoding to use.

  Specifically,

  `request_encode_url()` is for sending requests whose fields are encoded in the URL (such as GET, HEAD, DELETE).

  `request_encode_body()` is for sending requests whose fields are encoded in the body of the request using multipart or www-form-urlencoded (such as for POST, PUT, PATCH).

  `request()` is for making any kind of request, it will look up the appropriate encoding format and use one of the above two methods to make the request.

  Initializer parameters:

  Parameters: | headers – Headers to include with all requests, unless other headers are given explicitly.

  `request`(method, url, fields=None, headers=None, **urlopen_kw)

    Make a request using `urlopen()` with the appropriate encoding of `fields` based on the `method` used.

    This is a convenience method that requires the least amount of manual effort. It can be used in most situations, while still having the option to drop down to more specific methods when necessary, such as `request_encode_url()`, `request_encode_body()`, or even the lowest level `urlopen()`.

  `request_encode_body`(method, url, fields=None, headers=None, encode_multipart=True, multipart_boundary=None, **urlopen_kw)

    Make a request using `urlopen()` with the `fields` encoded in the body. This is useful for request methods like POST, PUT, PATCH, etc.

    When `encode_multipart=True` (default), then `urllib3.filepost.encode_multipart_formdata()` is used to encode the payload with the appropriate content type. Otherwise `urllib.urlencode()` is used with the ‘application/x-www-form-urlencoded’ content type.

    Multipart encoding must be used when posting files, and it’s reasonably safe to use it in other times too. However, it may break request signing, such as with OAuth.

    Supports an optional `fields` parameter of key/value strings AND key/filetuple. A filetuple is a (filename, data, MIME type) tuple where the MIME type is optional. For example:

        fields = {
            'foo': 'bar',
            'fakefile': ('foofile.txt', 'contents of foofile'),
            'realfile': ('barfile.txt', open('realfile').read()),
            'typedfile': ('bazfile.bin', open('bazfile').read(),
                          'image/jpeg'),
            'nonamefile': 'contents of nonamefile field',
        }

    When uploading a file, providing a filename (the first parameter of the tuple) is optional but recommended to best mimick behavior of browsers.

    Note that if `headers` are supplied, the ‘Content-Type’ header will be overwritten because it depends on the dynamic random boundary string which is used to compose the body of the request. The random boundary string can be explicitly set with the `multipart_boundary` parameter.

  `request_encode_url`(method, url, fields=None, headers=None, **urlopen_kw)

    Make a request using `urlopen()` with the `fields` encoded in the url. This is useful for request methods like GET, HEAD, DELETE, etc.

`urllib3.util.request.` `make_headers`(keep_alive=None, accept_encoding=None, user_agent=None, basic_auth=None, proxy_basic_auth=None, disable_cache=None)

  Shortcuts for generating request headers.

  Parameters: | keep_alive – If `True`, adds ‘connection: keep-alive’ header. accept_encoding – Can be a boolean, list, or string. `True` translates to ‘gzip,deflate’. List will get joined by comma. String will be used as provided. user_agent – String representing the user-agent you want, such as “python-urllib3/0.6” basic_auth – Colon-separated username:password string for ‘authorization: basic ...’ auth header. proxy_basic_auth – Colon-separated username:password string for ‘proxy-authorization: basic ...’ auth header. disable_cache – If `True`, adds ‘cache-control: no-cache’ header.

  Example:

      >>> make_headers(keep_alive=True, user_agent="Batman/1.0")
      {'connection': 'keep-alive', 'user-agent': 'Batman/1.0'}
      >>> make_headers(accept_encoding=True)
      {'accept-encoding': 'gzip,deflate'}

## Response

class `urllib3.response.` `DeflateDecoder`
  `decompress`(data)

class `urllib3.response.` `GzipDecoder`
  `decompress`(data)

class `urllib3.response.` `HTTPResponse`(body='', headers=None, status=0, version=0, reason=None, strict=0, preload_content=True, decode_content=True, original_response=None, pool=None, connection=None)

  HTTP Response container.

  Backwards-compatible to httplib’s HTTPResponse but the response `body` is loaded and decoded on-demand when the `data` property is accessed. This class is also compatible with the Python standard library’s `io` module, and can hence be treated as a readable object in the context of that framework.

  Extra parameters for behaviour not present in httplib.HTTPResponse:

  Parameters: | preload_content – If True, the response’s body will be preloaded during construction. decode_content – If True, attempts to decode specific content-encoding’s based on headers (like ‘gzip’ and ‘deflate’) will be skipped and raw data will be used instead. original_response – When this HTTPResponse wrapper is generated from an httplib.HTTPResponse object, it’s convenient to include the original for debug purposes. It’s otherwise unused.

  `CONTENT_DECODERS` = ['gzip', 'deflate']
  `REDIRECT_STATUSES` = [301, 302, 303, 307, 308]
  `close`()
  `closed`
  `connection`
  `data`
  `fileno`()
  `flush`()
  classmethod `from_httplib`(ResponseCls, r, **response_kw)

    Given an `httplib.HTTPResponse` instance `r`, return a corresponding `urllib3.response.HTTPResponse` object.

    Remaining parameters are passed to the HTTPResponse constructor, along with `original_response=r`.

  `get_redirect_location`()

    Should we redirect and where to?

    Returns: | Truthy redirect location string if we got a redirect status code and valid location. `None` if redirect status and no location. `False` if not a redirect status code.

  `getheader`(name, default=None)
  `getheaders`()
  `read`(amt=None, decode_content=None, cache_content=False)

    Similar to `httplib.HTTPResponse.read()`, but with two additional parameters: `decode_content` and `cache_content`.

    Parameters: | amt – How much of the content to read. If specified, caching is skipped because it doesn’t make sense to cache partial content as the full response. decode_content – If True, will attempt to decode the body based on the ‘content-encoding’ header. cache_content – If True, will save the returned data such that the same result is returned despite of the state of the underlying file object. This is useful if you want the `.data` property to continue working after having `.read()` the file object. (Overridden if `amt` is set.)

  `read_chunked`(amt=None, decode_content=None)

    Similar to `HTTPResponse.read()`, but with an additional parameter: `decode_content`.

    Parameters: | decode_content – If True, will attempt to decode the body based on the ‘content-encoding’ header.

  `readable`()
  `readinto`(b)
  `release_conn`()
  `stream`(amt=65536, decode_content=None)

    A generator wrapper for the read() method. A call will block until `amt` bytes have been read from the connection or until the connection is closed.

    Parameters: | amt – How much of the content to read. The generator will return up to much data per iteration, but may return less. This is particularly likely when using compressed data. However, the empty string will never be returned. decode_content – If True, will attempt to decode the body based on the ‘content-encoding’ header.

  `tell`()

    Obtain the number of bytes pulled over the wire so far. May differ from the amount of content returned by :meth:`HTTPResponse.read` if bytes are encoded on the wire (e.g, compressed).

## SSL/TLS Helpers

`urllib3.util.ssl_.` `assert_fingerprint`(cert, fingerprint)

  Checks if given fingerprint matches the supplied certificate.

  Parameters: | cert – Certificate as bytes object. fingerprint – Fingerprint as string of hexdigits, can be interspersed by colons.

`urllib3.util.ssl_.` `create_urllib3_context`(ssl_version=None, cert_reqs=None, options=None, ciphers=None)

  All arguments have the same meaning as `ssl_wrap_socket`.

  By default, this function does a lot of the same work that `ssl.create_default_context` does on Python 3.4+. It:

  - Disables SSLv2, SSLv3, and compression
  - Sets a restricted set of server ciphers

  If you wish to enable SSLv3, you can do:

      from urllib3.util import ssl_
      context = ssl_.create_urllib3_context()
      context.options &= ~ssl_.OP_NO_SSLv3

  You can do the same to enable compression (substituting `COMPRESSION` for `SSLv3` in the last line above).

  Parameters: | ssl_version – The desired protocol version to use. This will default to PROTOCOL_SSLv23 which will negotiate the highest protocol that both the server and your installation of OpenSSL support. cert_reqs – Whether to require the certificate verification. This defaults to `ssl.CERT_REQUIRED`. options – Specific OpenSSL options. These default to `ssl.OP_NO_SSLv2`, `ssl.OP_NO_SSLv3`, `ssl.OP_NO_COMPRESSION`. ciphers – Which cipher suites to allow the server to select.
  Returns: | Constructed SSLContext object with specified options
  Return type: | SSLContext

`urllib3.util.ssl_.` `resolve_cert_reqs`(candidate)

  Resolves the argument to a numeric constant, which can be passed to the wrap_socket function/method from the ssl module. Defaults to `ssl.CERT_NONE`. If given a string it is assumed to be the name of the constant in the `ssl` module or its abbrevation. (So you can specify REQUIRED instead of CERT_REQUIRED. If it’s neither None nor a string we assume it is already the numeric constant which can directly be passed to wrap_socket.

`urllib3.util.ssl_.` `resolve_ssl_version`(candidate)

  like resolve_cert_reqs

`urllib3.util.ssl_.` `ssl_wrap_socket`(sock, keyfile=None, certfile=None, cert_reqs=None, ca_certs=None, server_hostname=None, ssl_version=None, ciphers=None, ssl_context=None, ca_cert_dir=None)

  All arguments except for server_hostname, ssl_context, and ca_cert_dir have the same meaning as they do when using `ssl.wrap_socket()`.

  Parameters: | server_hostname – When SNI is supported, the expected hostname of the certificate ssl_context – A pre-made `SSLContext` object. If none is provided, one will be created using `create_urllib3_context()`. ciphers – A string of ciphers we wish the client to support. This is not supported on Python 2.6 as the ssl module does not support it. ca_cert_dir – A directory containing CA certificates in multiple separate files, as supported by OpenSSL’s -CApath flag or the capath argument to SSLContext.load_verify_locations().