Application: gvSIG desktop » gvSIG scripting

from __future__ import absolute_import

from contextlib import contextmanager

import zlib

import io

from socket import timeout as SocketTimeout

from socket import error as SocketError

from ._collections import HTTPHeaderDict

from .exceptions import (

    ProtocolError, DecodeError, ReadTimeoutError, ResponseNotChunked

)

from .packages.six import string_types as basestring, binary_type, PY3

from .packages.six.moves import http_client as httplib

from .connection import HTTPException, BaseSSLError

from .util.response import is_fp_closed, is_response_to_head

class DeflateDecoder(object):

    def __init__(self):

        self._first_try = True

        self._data = binary_type()

        self._obj = zlib.decompressobj()

    def __getattr__(self, name):

        return getattr(self._obj, name)

    def decompress(self, data):

        if not data:

            return data

        if not self._first_try:

            return self._obj.decompress(data)

        self._data += data

        try:

            return self._obj.decompress(data)

        except zlib.error:

            self._first_try = False

            self._obj = zlib.decompressobj(-zlib.MAX_WBITS)

            try:

                return self.decompress(self._data)

            finally:

                self._data = None

class GzipDecoder(object):

    def __init__(self):

        self._obj = zlib.decompressobj(16 + zlib.MAX_WBITS)

    def __getattr__(self, name):

        return getattr(self._obj, name)

    def decompress(self, data):

        if not data:

            return data

        return self._obj.decompress(data)

def _get_decoder(mode):

    if mode == 'gzip':

        return GzipDecoder()

    return DeflateDecoder()

class HTTPResponse(io.IOBase):

    """

    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 :mod:`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:

    :param preload_content:

        If True, the response's body will be preloaded during construction.

    :param 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.

    :param 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]

    def __init__(self, body='', headers=None, status=0, version=0, reason=None,

                 strict=0, preload_content=True, decode_content=True,

                 original_response=None, pool=None, connection=None):

        if isinstance(headers, HTTPHeaderDict):

            self.headers = headers

        else:

            self.headers = HTTPHeaderDict(headers)

        self.status = status

        self.version = version

        self.reason = reason

        self.strict = strict

        self.decode_content = decode_content

        self._decoder = None

        self._body = None

        self._fp = None

        self._original_response = original_response

        self._fp_bytes_read = 0

        if body and isinstance(body, (basestring, binary_type)):

            self._body = body

        self._pool = pool

        self._connection = connection

        if hasattr(body, 'read'):

            self._fp = body

        # Are we using the chunked-style of transfer encoding?

        self.chunked = False

        self.chunk_left = None

        tr_enc = self.headers.get('transfer-encoding', '').lower()

        # Don't incur the penalty of creating a list and then discarding it

        encodings = (enc.strip() for enc in tr_enc.split(","))

        if "chunked" in encodings:

            self.chunked = True

        # If requested, preload the body.

        if preload_content and not self._body:

            self._body = self.read(decode_content=decode_content)

    def get_redirect_location(self):

        """

        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.

        """

        if self.status in self.REDIRECT_STATUSES:

            return self.headers.get('location')

        return False

    def release_conn(self):

        if not self._pool or not self._connection:

            return

        self._pool._put_conn(self._connection)

        self._connection = None

    @property

    def data(self):

        # For backwords-compat with earlier urllib3 0.4 and earlier.

        if self._body:

            return self._body

        if self._fp:

            return self.read(cache_content=True)

    def tell(self):

        """

        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).

        """

        return self._fp_bytes_read

    def _init_decoder(self):

        """

        Set-up the _decoder attribute if necessar.

        """

        # Note: content-encoding value should be case-insensitive, per RFC 7230

        # Section 3.2

        content_encoding = self.headers.get('content-encoding', '').lower()

        if self._decoder is None and content_encoding in self.CONTENT_DECODERS:

            self._decoder = _get_decoder(content_encoding)

    def _decode(self, data, decode_content, flush_decoder):

        """

        Decode the data passed in and potentially flush the decoder.

        """

        try:

            if decode_content and self._decoder:

                data = self._decoder.decompress(data)

        except (IOError, zlib.error) as e:

            content_encoding = self.headers.get('content-encoding', '').lower()

            raise DecodeError(

                "Received response with content-encoding: %s, but "

                "failed to decode it." % content_encoding, e)

        if flush_decoder and decode_content:

            data += self._flush_decoder()

        return data

    def _flush_decoder(self):

        """

        Flushes the decoder. Should only be called if the decoder is actually

        being used.

        """

        if self._decoder:

            buf = self._decoder.decompress(b'')

            return buf + self._decoder.flush()

        return b''

    @contextmanager

    def _error_catcher(self):

        """

        Catch low-level python exceptions, instead re-raising urllib3

        variants, so that low-level exceptions are not leaked in the

        high-level api.

        On exit, release the connection back to the pool.

        """

        try:

            try:

                yield

            except SocketTimeout:

                # FIXME: Ideally we'd like to include the url in the ReadTimeoutError but

                # there is yet no clean way to get at it from this context.

                raise ReadTimeoutError(self._pool, None, 'Read timed out.')

            except BaseSSLError as e:

                # FIXME: Is there a better way to differentiate between SSLErrors?

                if 'read operation timed out' not in str(e):  # Defensive:

                    # This shouldn't happen but just in case we're missing an edge

                    # case, let's avoid swallowing SSL errors.

                    raise

                raise ReadTimeoutError(self._pool, None, 'Read timed out.')

            except (HTTPException, SocketError) as e:

                # This includes IncompleteRead.

                raise ProtocolError('Connection broken: %r' % e, e)

        except Exception:

            # The response may not be closed but we're not going to use it anymore

            # so close it now to ensure that the connection is released back to the pool.

            if self._original_response and not self._original_response.isclosed():

                self._original_response.close()

            # Closing the response may not actually be sufficient to close

            # everything, so if we have a hold of the connection close that

            # too.

            if self._connection is not None:

                self._connection.close()

            raise

        finally:

            if self._original_response and self._original_response.isclosed():

                self.release_conn()

    def read(self, amt=None, decode_content=None, cache_content=False):

        """

        Similar to :meth:`httplib.HTTPResponse.read`, but with two additional

        parameters: ``decode_content`` and ``cache_content``.

        :param 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.

        :param decode_content:

            If True, will attempt to decode the body based on the

            'content-encoding' header.

        :param 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.)

        """

        self._init_decoder()

        if decode_content is None:

            decode_content = self.decode_content

        if self._fp is None:

            return

        flush_decoder = False

        data = None

        with self._error_catcher():

            if amt is None:

                # cStringIO doesn't like amt=None

                data = self._fp.read()

                flush_decoder = True

            else:

                cache_content = False

                data = self._fp.read(amt)

                if amt != 0 and not data:  # Platform-specific: Buggy versions of Python.

                    # Close the connection when no data is returned

                    #

                    # This is redundant to what httplib/http.client _should_

                    # already do.  However, versions of python released before

                    # December 15, 2012 (http://bugs.python.org/issue16298) do

                    # not properly close the connection in all cases. There is

                    # no harm in redundantly calling close.

                    self._fp.close()

                    flush_decoder = True

        if data:

            self._fp_bytes_read += len(data)

            data = self._decode(data, decode_content, flush_decoder)

            if cache_content:

                self._body = data

        return data

    def stream(self, amt=2**16, 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.

        :param 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.

        :param decode_content:

            If True, will attempt to decode the body based on the

            'content-encoding' header.

        """

        if self.chunked:

            for line in self.read_chunked(amt, decode_content=decode_content):

                yield line

        else:

            while not is_fp_closed(self._fp):

                data = self.read(amt=amt, decode_content=decode_content)

                if data:

                    yield data

    @classmethod

    def from_httplib(ResponseCls, r, **response_kw):

        """

        Given an :class:`httplib.HTTPResponse` instance ``r``, return a

        corresponding :class:`urllib3.response.HTTPResponse` object.

        Remaining parameters are passed to the HTTPResponse constructor, along

        with ``original_response=r``.

        """

        headers = r.msg

        if not isinstance(headers, HTTPHeaderDict):

            if PY3:  # Python 3

                headers = HTTPHeaderDict(headers.items())

            else:  # Python 2

                headers = HTTPHeaderDict.from_httplib(headers)

        # HTTPResponse objects in Python 3 don't have a .strict attribute

        strict = getattr(r, 'strict', 0)

        resp = ResponseCls(body=r,

                           headers=headers,

                           status=r.status,

                           version=r.version,

                           reason=r.reason,

                           strict=strict,

                           original_response=r,

                           **response_kw)

        return resp

    # Backwards-compatibility methods for httplib.HTTPResponse

    def getheaders(self):

        return self.headers

    def getheader(self, name, default=None):

        return self.headers.get(name, default)

    # Overrides from io.IOBase

    def close(self):

        if not self.closed:

            self._fp.close()

    @property

    def closed(self):

        if self._fp is None:

            return True

        elif hasattr(self._fp, 'closed'):

            return self._fp.closed

        elif hasattr(self._fp, 'isclosed'):  # Python 2

            return self._fp.isclosed()

        else:

            return True

    def fileno(self):

        if self._fp is None:

            raise IOError("HTTPResponse has no file to get a fileno from")

        elif hasattr(self._fp, "fileno"):

            return self._fp.fileno()

        else:

            raise IOError("The file-like object this HTTPResponse is wrapped "

                          "around has no file descriptor")

    def flush(self):

        if self._fp is not None and hasattr(self._fp, 'flush'):

            return self._fp.flush()

    def readable(self):

        # This method is required for `io` module compatibility.

        return True

    def readinto(self, b):

        # This method is required for `io` module compatibility.

        temp = self.read(len(b))

        if len(temp) == 0:

            return 0

        else:

            b[:len(temp)] = temp

            return len(temp)

    def _update_chunk_length(self):

        # First, we'll figure out length of a chunk and then

        # we'll try to read it from socket.

        if self.chunk_left is not None:

            return

        line = self._fp.fp.readline()

        line = line.split(b';', 1)[0]

        try:

            self.chunk_left = int(line, 16)

        except ValueError:

            # Invalid chunked protocol response, abort.

            self.close()

            raise httplib.IncompleteRead(line)

    def _handle_chunk(self, amt):

        returned_chunk = None

        if amt is None:

            chunk = self._fp._safe_read(self.chunk_left)

            returned_chunk = chunk

            self._fp._safe_read(2)  # Toss the CRLF at the end of the chunk.

            self.chunk_left = None

        elif amt < self.chunk_left:

            value = self._fp._safe_read(amt)

            self.chunk_left = self.chunk_left - amt

            returned_chunk = value

        elif amt == self.chunk_left:

            value = self._fp._safe_read(amt)

            self._fp._safe_read(2)  # Toss the CRLF at the end of the chunk.

            self.chunk_left = None

            returned_chunk = value

        else:  # amt > self.chunk_left

            returned_chunk = self._fp._safe_read(self.chunk_left)

            self._fp._safe_read(2)  # Toss the CRLF at the end of the chunk.

            self.chunk_left = None

        return returned_chunk

    def read_chunked(self, amt=None, decode_content=None):

        """

        Similar to :meth:`HTTPResponse.read`, but with an additional

        parameter: ``decode_content``.

        :param decode_content:

            If True, will attempt to decode the body based on the

            'content-encoding' header.

        """

        self._init_decoder()

        # FIXME: Rewrite this method and make it a class with a better structured logic.

        if not self.chunked:

            raise ResponseNotChunked(

                "Response is not chunked. "

                "Header 'transfer-encoding: chunked' is missing.")

        # Don't bother reading the body of a HEAD request.

        if self._original_response and is_response_to_head(self._original_response):

            self._original_response.close()

            return

        with self._error_catcher():

            while True:

                self._update_chunk_length()

                if self.chunk_left == 0:

                    break

                chunk = self._handle_chunk(amt)

                decoded = self._decode(chunk, decode_content=decode_content,

                                       flush_decoder=False)

                if decoded:

                    yield decoded

            if decode_content:

                # On CPython and PyPy, we should never need to flush the

                # decoder. However, on Jython we *might* need to, so

                # lets defensively do it anyway.

                decoded = self._flush_decoder()

                if decoded:  # Platform-specific: Jython.

                    yield decoded

            # Chunk content ends with \r\n: discard it.

            while True:

                line = self._fp.fp.readline()

                if not line:

                    # Some sites may not end with '\r\n'.

                    break

                if line == b'\r\n':

                    break

            # We read everything; close the "file".

            if self._original_response:

                self._original_response.close()