daphne/channels/handler.py
2016-03-23 12:53:02 -07:00

318 lines
11 KiB
Python

from __future__ import unicode_literals
import cgi
import codecs
import logging
import sys
import traceback
from io import BytesIO
from threading import Lock
from django import http
from django.conf import settings
from django.core import signals
from django.core.handlers import base
from django.core.urlresolvers import set_script_prefix
from django.http import FileResponse, HttpResponseServerError
from django.utils import six
from django.utils.functional import cached_property
from .exceptions import ResponseLater as ResponseLaterOuter
logger = logging.getLogger('django.request')
class AsgiRequest(http.HttpRequest):
"""
Custom request subclass that decodes from an ASGI-standard request
dict, and wraps request body handling.
"""
ResponseLater = ResponseLaterOuter
def __init__(self, message):
self.message = message
self.reply_channel = self.message.reply_channel
self._content_length = 0
self._post_parse_error = False
self.resolver_match = None
# Path info
self.path = self.message['path'].decode("ascii")
self.script_name = self.message.get('root_path', b'')
if self.script_name:
# TODO: Better is-prefix checking, slash handling?
self.path_info = self.path[len(self.script_name):]
else:
self.path_info = self.path
# HTTP basics
self.method = self.message['method'].upper()
self.META = {
"REQUEST_METHOD": self.method,
"QUERY_STRING": self.message.get('query_string', b'').decode("ascii"),
"SCRIPT_NAME": self.script_name.decode("ascii"),
# Old code will need these for a while
"wsgi.multithread": True,
"wsgi.multiprocess": True,
}
if self.message.get('client', None):
self.META['REMOTE_ADDR'] = self.message['client'][0]
self.META['REMOTE_HOST'] = self.META['REMOTE_ADDR']
self.META['REMOTE_PORT'] = self.message['client'][1]
if self.message.get('server', None):
self.META['SERVER_NAME'] = self.message['server'][0]
self.META['SERVER_PORT'] = self.message['server'][1]
# Handle old style-headers for a transition period
if "headers" in self.message and isinstance(self.message['headers'], dict):
self.message['headers'] = [
(x.encode("latin1"), y) for x, y in
self.message['headers'].items()
]
# Headers go into META
for name, value in self.message.get('headers', []):
name = name.decode("latin1")
if name == "content-length":
corrected_name = "CONTENT_LENGTH"
elif name == "content-type":
corrected_name = "CONTENT_TYPE"
else:
corrected_name = 'HTTP_%s' % name.upper().replace("-", "_")
# HTTPbis say only ASCII chars are allowed in headers, but we latin1 just in case
value = value.decode("latin1")
if corrected_name in self.META:
value = self.META[corrected_name] + "," + value.decode("latin1")
self.META[corrected_name] = value
# Pull out request encoding if we find it
if "CONTENT_TYPE" in self.META:
_, content_params = cgi.parse_header(self.META["CONTENT_TYPE"])
if 'charset' in content_params:
try:
codecs.lookup(content_params['charset'])
except LookupError:
pass
else:
self.encoding = content_params['charset']
# Pull out content length info
if self.META.get('CONTENT_LENGTH', None):
try:
self._content_length = int(self.META['CONTENT_LENGTH'])
except (ValueError, TypeError):
pass
# Body handling
self._body = message.get("body", b"")
if message.get("body_channel", None):
while True:
# Get the next chunk from the request body channel
chunk = None
while chunk is None:
_, chunk = message.channel_layer.receive_many(
[message['body_channel']],
block=True,
)
# Add content to body
self._body += chunk.get("content", "")
# Exit loop if this was the last
if not chunk.get("more_content", False):
break
assert isinstance(self._body, six.binary_type), "Body is not bytes"
# Add a stream-a-like for the body
self._stream = BytesIO(self._body)
# Other bits
self.resolver_match = None
@cached_property
def GET(self):
return http.QueryDict(
self.message.get('query_string', ''),
encoding=self._encoding,
)
def _get_post(self):
if not hasattr(self, '_post'):
self._read_started = False
self._load_post_and_files()
return self._post
def _set_post(self, post):
self._post = post
def _get_files(self):
if not hasattr(self, '_files'):
self._load_post_and_files()
return self._files
POST = property(_get_post, _set_post)
FILES = property(_get_files)
@cached_property
def COOKIES(self):
return http.parse_cookie(self.META.get('HTTP_COOKIE', ''))
class AsgiHandler(base.BaseHandler):
"""
Handler for ASGI requests for the view system only (it will have got here
after traversing the dispatch-by-channel-name system, which decides it's
a HTTP request)
"""
initLock = Lock()
request_class = AsgiRequest
# Size to chunk response bodies into for multiple response messages
chunk_size = 512 * 1024
def __call__(self, message):
# Set up middleware if needed. We couldn't do this earlier, because
# settings weren't available.
if self._request_middleware is None:
with self.initLock:
# Check that middleware is still uninitialized.
if self._request_middleware is None:
self.load_middleware()
# Set script prefix from message root_path
set_script_prefix(message.get('root_path', ''))
signals.request_started.send(sender=self.__class__, message=message)
# Run request through view system
try:
request = self.request_class(message)
except UnicodeDecodeError:
logger.warning(
'Bad Request (UnicodeDecodeError)',
exc_info=sys.exc_info(),
extra={
'status_code': 400,
}
)
response = http.HttpResponseBadRequest()
else:
try:
response = self.get_response(request)
# Fix chunk size on file responses
if isinstance(response, FileResponse):
response.block_size = 1024 * 512
except AsgiRequest.ResponseLater:
# The view has promised something else
# will send a response at a later time
return
# Transform response into messages, which we yield back to caller
for message in self.encode_response(response):
# TODO: file_to_stream
yield message
def process_exception_by_middleware(self, exception, request):
"""
Catches ResponseLater and re-raises it, else tries to delegate
to middleware exception handling.
"""
if isinstance(exception, AsgiRequest.ResponseLater):
raise
else:
return super(AsgiHandler, self).process_exception_by_middleware(exception, request)
def handle_uncaught_exception(self, request, resolver, exc_info):
"""
Propagates ResponseLater up into the higher handler method,
processes everything else
"""
# ResponseLater needs to be bubbled up the stack
if issubclass(exc_info[0], AsgiRequest.ResponseLater):
raise
# There's no WSGI server to catch the exception further up if this fails,
# so translate it into a plain text response.
try:
return super(AsgiHandler, self).handle_uncaught_exception(request, resolver, exc_info)
except:
return HttpResponseServerError(
traceback.format_exc() if settings.DEBUG else "Internal Server Error",
content_type="text/plain",
)
@classmethod
def encode_response(cls, response):
"""
Encodes a Django HTTP response into ASGI http.response message(s).
"""
# Collect cookies into headers.
# Note that we have to preserve header case as there are some non-RFC
# compliant clients that want things like Content-Type correct. Ugh.
response_headers = []
for header, value in response.items():
if isinstance(header, six.text_type):
header = header.encode("ascii")
if isinstance(value, six.text_type):
value = value.encode("latin1")
response_headers.append(
(
six.binary_type(header),
six.binary_type(value),
)
)
for c in response.cookies.values():
response_headers.append(
(
b'Set-Cookie',
c.output(header='').encode("ascii"),
)
)
# Make initial response message
message = {
"status": response.status_code,
"headers": response_headers,
}
# Streaming responses need to be pinned to their iterator
if response.streaming:
for part in response.streaming_content:
for chunk, more in cls.chunk_bytes(part):
message['content'] = chunk
# We ignore "more" as there may be more parts; instead,
# we use an empty final closing message with False.
message['more_content'] = True
yield message
message = {}
# Final closing message
yield {
"more_content": False,
}
# Other responses just need chunking
else:
# Yield chunks of response
for chunk, last in cls.chunk_bytes(response.content):
message['content'] = chunk
message['more_content'] = not last
yield message
message = {}
@classmethod
def chunk_bytes(cls, data):
"""
Chunks some data into chunks based on the current ASGI channel layer's
message size and reasonable defaults.
Yields (chunk, last_chunk) tuples.
"""
position = 0
if not data:
yield data, True
return
while position < len(data):
yield (
data[position:position + cls.chunk_size],
(position + cls.chunk_size) >= len(data),
)
position += cls.chunk_size
class ViewConsumer(object):
"""
Dispatches channel HTTP requests into django's URL/View system.
"""
handler_class = AsgiHandler
def __init__(self):
self.handler = self.handler_class()
def __call__(self, message):
for reply_message in self.handler(message):
message.reply_channel.send(reply_message)