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httptools_impl.py
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httptools_impl.py
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import asyncio
import http
import logging
import re
import urllib
from collections import deque
from typing import Callable
import httptools
from uvicorn.logging import TRACE_LOG_LEVEL
from uvicorn.protocols.http.flow_control import (
CLOSE_HEADER,
HIGH_WATER_LIMIT,
FlowControl,
service_unavailable,
)
from uvicorn.protocols.utils import (
get_client_addr,
get_local_addr,
get_path_with_query_string,
get_remote_addr,
is_ssl,
)
HEADER_RE = re.compile(b'[\x00-\x1F\x7F()<>@,;:[]={} \t\\"]')
HEADER_VALUE_RE = re.compile(b"[\x00-\x1F\x7F]")
def _get_status_line(status_code):
try:
phrase = http.HTTPStatus(status_code).phrase.encode()
except ValueError:
phrase = b""
return b"".join([b"HTTP/1.1 ", str(status_code).encode(), b" ", phrase, b"\r\n"])
STATUS_LINE = {
status_code: _get_status_line(status_code) for status_code in range(100, 600)
}
class HttpToolsProtocol(asyncio.Protocol):
def __init__(
self, config, server_state, on_connection_lost: Callable = None, _loop=None
):
if not config.loaded:
config.load()
self.config = config
self.app = config.loaded_app
self.on_connection_lost = on_connection_lost
self.loop = _loop or asyncio.get_event_loop()
self.logger = logging.getLogger("uvicorn.error")
self.access_logger = logging.getLogger("uvicorn.access")
self.access_log = self.access_logger.hasHandlers()
self.parser = httptools.HttpRequestParser(self)
self.ws_protocol_class = config.ws_protocol_class
self.root_path = config.root_path
self.limit_concurrency = config.limit_concurrency
# Timeouts
self.timeout_keep_alive_task = None
self.timeout_keep_alive = config.timeout_keep_alive
# Global state
self.server_state = server_state
self.connections = server_state.connections
self.tasks = server_state.tasks
self.default_headers = server_state.default_headers
# Per-connection state
self.transport = None
self.flow = None
self.server = None
self.client = None
self.scheme = None
self.pipeline = deque()
# Per-request state
self.url = None
self.scope = None
self.headers = None
self.expect_100_continue = False
self.cycle = None
# Protocol interface
def connection_made(self, transport):
self.connections.add(self)
self.transport = transport
self.flow = FlowControl(transport)
self.server = get_local_addr(transport)
self.client = get_remote_addr(transport)
self.scheme = "https" if is_ssl(transport) else "http"
if self.logger.level <= TRACE_LOG_LEVEL:
prefix = "%s:%d - " % tuple(self.client) if self.client else ""
self.logger.log(TRACE_LOG_LEVEL, "%sHTTP connection made", prefix)
def connection_lost(self, exc):
self.connections.discard(self)
if self.logger.level <= TRACE_LOG_LEVEL:
prefix = "%s:%d - " % tuple(self.client) if self.client else ""
self.logger.log(TRACE_LOG_LEVEL, "%sHTTP connection lost", prefix)
if self.cycle and not self.cycle.response_complete:
self.cycle.disconnected = True
if self.cycle is not None:
self.cycle.message_event.set()
if self.flow is not None:
self.flow.resume_writing()
if exc is None:
self.transport.close()
if self.on_connection_lost is not None:
self.on_connection_lost()
def eof_received(self):
pass
def _unset_keepalive_if_required(self):
if self.timeout_keep_alive_task is not None:
self.timeout_keep_alive_task.cancel()
self.timeout_keep_alive_task = None
def data_received(self, data):
self._unset_keepalive_if_required()
try:
self.parser.feed_data(data)
except httptools.HttpParserError as exc:
msg = "Invalid HTTP request received."
self.logger.warning(msg, exc_info=exc)
self.transport.close()
except httptools.HttpParserUpgrade:
self.handle_upgrade()
def handle_upgrade(self):
upgrade_value = None
for name, value in self.headers:
if name == b"upgrade":
upgrade_value = value.lower()
if upgrade_value != b"websocket" or self.ws_protocol_class is None:
msg = "Unsupported upgrade request."
self.logger.warning(msg)
from uvicorn.protocols.websockets.auto import AutoWebSocketsProtocol
if AutoWebSocketsProtocol is None:
msg = "No supported WebSocket library detected. Please use 'pip install uvicorn[standard]', or install 'websockets' or 'wsproto' manually." # noqa: E501
self.logger.warning(msg)
content = [STATUS_LINE[400]]
for name, value in self.default_headers:
content.extend([name, b": ", value, b"\r\n"])
content.extend(
[
b"content-type: text/plain; charset=utf-8\r\n",
b"content-length: " + str(len(msg)).encode("ascii") + b"\r\n",
b"connection: close\r\n",
b"\r\n",
msg.encode("ascii"),
]
)
self.transport.write(b"".join(content))
self.transport.close()
return
if self.logger.level <= TRACE_LOG_LEVEL:
prefix = "%s:%d - " % tuple(self.client) if self.client else ""
self.logger.log(TRACE_LOG_LEVEL, "%sUpgrading to WebSocket", prefix)
self.connections.discard(self)
method = self.scope["method"].encode()
output = [method, b" ", self.url, b" HTTP/1.1\r\n"]
for name, value in self.scope["headers"]:
output += [name, b": ", value, b"\r\n"]
output.append(b"\r\n")
protocol = self.ws_protocol_class(
config=self.config,
server_state=self.server_state,
on_connection_lost=self.on_connection_lost,
)
protocol.connection_made(self.transport)
protocol.data_received(b"".join(output))
self.transport.set_protocol(protocol)
# Parser callbacks
def on_url(self, url):
method = self.parser.get_method()
parsed_url = httptools.parse_url(url)
raw_path = parsed_url.path
path = raw_path.decode("ascii")
if "%" in path:
path = urllib.parse.unquote(path)
self.url = url
self.expect_100_continue = False
self.headers = []
self.scope = {
"type": "http",
"asgi": {"version": self.config.asgi_version, "spec_version": "2.3"},
"http_version": "1.1",
"server": self.server,
"client": self.client,
"scheme": self.scheme,
"method": method.decode("ascii"),
"root_path": self.root_path,
"path": path,
"raw_path": raw_path,
"query_string": parsed_url.query if parsed_url.query else b"",
"headers": self.headers,
}
def on_header(self, name: bytes, value: bytes):
name = name.lower()
if name == b"expect" and value.lower() == b"100-continue":
self.expect_100_continue = True
self.headers.append((name, value))
def on_headers_complete(self):
http_version = self.parser.get_http_version()
if http_version != "1.1":
self.scope["http_version"] = http_version
if self.parser.should_upgrade():
return
# Handle 503 responses when 'limit_concurrency' is exceeded.
if self.limit_concurrency is not None and (
len(self.connections) >= self.limit_concurrency
or len(self.tasks) >= self.limit_concurrency
):
app = service_unavailable
message = "Exceeded concurrency limit."
self.logger.warning(message)
else:
app = self.app
existing_cycle = self.cycle
self.cycle = RequestResponseCycle(
scope=self.scope,
transport=self.transport,
flow=self.flow,
logger=self.logger,
access_logger=self.access_logger,
access_log=self.access_log,
default_headers=self.default_headers,
message_event=asyncio.Event(),
expect_100_continue=self.expect_100_continue,
keep_alive=http_version != "1.0",
on_response=self.on_response_complete,
)
if existing_cycle is None or existing_cycle.response_complete:
# Standard case - start processing the request.
task = self.loop.create_task(self.cycle.run_asgi(app))
task.add_done_callback(self.tasks.discard)
self.tasks.add(task)
else:
# Pipelined HTTP requests need to be queued up.
self.flow.pause_reading()
self.pipeline.appendleft((self.cycle, app))
def on_body(self, body: bytes):
if self.parser.should_upgrade() or self.cycle.response_complete:
return
self.cycle.body += body
if len(self.cycle.body) > HIGH_WATER_LIMIT:
self.flow.pause_reading()
self.cycle.message_event.set()
def on_message_complete(self):
if self.parser.should_upgrade() or self.cycle.response_complete:
return
self.cycle.more_body = False
self.cycle.message_event.set()
def on_response_complete(self):
# Callback for pipelined HTTP requests to be started.
self.server_state.total_requests += 1
if self.transport.is_closing():
return
# Set a short Keep-Alive timeout.
self._unset_keepalive_if_required()
self.timeout_keep_alive_task = self.loop.call_later(
self.timeout_keep_alive, self.timeout_keep_alive_handler
)
# Unpause data reads if needed.
self.flow.resume_reading()
# Unblock any pipelined events.
if self.pipeline:
cycle, app = self.pipeline.pop()
task = self.loop.create_task(cycle.run_asgi(app))
task.add_done_callback(self.tasks.discard)
self.tasks.add(task)
def shutdown(self):
"""
Called by the server to commence a graceful shutdown.
"""
if self.cycle is None or self.cycle.response_complete:
self.transport.close()
else:
self.cycle.keep_alive = False
def pause_writing(self):
"""
Called by the transport when the write buffer exceeds the high water mark.
"""
self.flow.pause_writing()
def resume_writing(self):
"""
Called by the transport when the write buffer drops below the low water mark.
"""
self.flow.resume_writing()
def timeout_keep_alive_handler(self):
"""
Called on a keep-alive connection if no new data is received after a short
delay.
"""
if not self.transport.is_closing():
self.transport.close()
class RequestResponseCycle:
def __init__(
self,
scope,
transport,
flow,
logger,
access_logger,
access_log,
default_headers,
message_event,
expect_100_continue,
keep_alive,
on_response,
):
self.scope = scope
self.transport = transport
self.flow = flow
self.logger = logger
self.access_logger = access_logger
self.access_log = access_log
self.default_headers = default_headers
self.message_event = message_event
self.on_response = on_response
# Connection state
self.disconnected = False
self.keep_alive = keep_alive
self.waiting_for_100_continue = expect_100_continue
# Request state
self.body = b""
self.more_body = True
# Response state
self.response_started = False
self.response_complete = False
self.chunked_encoding = None
self.expected_content_length = 0
# ASGI exception wrapper
async def run_asgi(self, app):
try:
result = await app(self.scope, self.receive, self.send)
except BaseException as exc:
msg = "Exception in ASGI application\n"
self.logger.error(msg, exc_info=exc)
if not self.response_started:
await self.send_500_response()
else:
self.transport.close()
else:
if result is not None:
msg = "ASGI callable should return None, but returned '%s'."
self.logger.error(msg, result)
self.transport.close()
elif not self.response_started and not self.disconnected:
msg = "ASGI callable returned without starting response."
self.logger.error(msg)
await self.send_500_response()
elif not self.response_complete and not self.disconnected:
msg = "ASGI callable returned without completing response."
self.logger.error(msg)
self.transport.close()
finally:
self.on_response = None
async def send_500_response(self):
await self.send(
{
"type": "http.response.start",
"status": 500,
"headers": [
(b"content-type", b"text/plain; charset=utf-8"),
(b"connection", b"close"),
],
}
)
await self.send(
{"type": "http.response.body", "body": b"Internal Server Error"}
)
# ASGI interface
async def send(self, message):
message_type = message["type"]
if self.flow.write_paused and not self.disconnected:
await self.flow.drain()
if self.disconnected:
return
if not self.response_started:
# Sending response status line and headers
if message_type != "http.response.start":
msg = "Expected ASGI message 'http.response.start', but got '%s'."
raise RuntimeError(msg % message_type)
self.response_started = True
self.waiting_for_100_continue = False
status_code = message["status"]
headers = self.default_headers + list(message.get("headers", []))
if CLOSE_HEADER in self.scope["headers"] and CLOSE_HEADER not in headers:
headers = headers + [CLOSE_HEADER]
if self.access_log:
self.access_logger.info(
'%s - "%s %s HTTP/%s" %d',
get_client_addr(self.scope),
self.scope["method"],
get_path_with_query_string(self.scope),
self.scope["http_version"],
status_code,
)
# Write response status line and headers
content = [STATUS_LINE[status_code]]
for name, value in headers:
if HEADER_RE.search(name):
raise RuntimeError("Invalid HTTP header name.")
if HEADER_VALUE_RE.search(value):
raise RuntimeError("Invalid HTTP header value.")
name = name.lower()
if name == b"content-length" and self.chunked_encoding is None:
self.expected_content_length = int(value.decode())
self.chunked_encoding = False
elif name == b"transfer-encoding" and value.lower() == b"chunked":
self.expected_content_length = 0
self.chunked_encoding = True
elif name == b"connection" and value.lower() == b"close":
self.keep_alive = False
content.extend([name, b": ", value, b"\r\n"])
if (
self.chunked_encoding is None
and self.scope["method"] != "HEAD"
and status_code not in (204, 304)
):
# Neither content-length nor transfer-encoding specified
self.chunked_encoding = True
content.append(b"transfer-encoding: chunked\r\n")
content.append(b"\r\n")
self.transport.write(b"".join(content))
elif not self.response_complete:
# Sending response body
if message_type != "http.response.body":
msg = "Expected ASGI message 'http.response.body', but got '%s'."
raise RuntimeError(msg % message_type)
body = message.get("body", b"")
more_body = message.get("more_body", False)
# Write response body
if self.scope["method"] == "HEAD":
self.expected_content_length = 0
elif self.chunked_encoding:
if body:
content = [b"%x\r\n" % len(body), body, b"\r\n"]
else:
content = []
if not more_body:
content.append(b"0\r\n\r\n")
self.transport.write(b"".join(content))
else:
num_bytes = len(body)
if num_bytes > self.expected_content_length:
raise RuntimeError("Response content longer than Content-Length")
else:
self.expected_content_length -= num_bytes
self.transport.write(body)
# Handle response completion
if not more_body:
if self.expected_content_length != 0:
raise RuntimeError("Response content shorter than Content-Length")
self.response_complete = True
self.message_event.set()
if not self.keep_alive:
self.transport.close()
self.on_response()
else:
# Response already sent
msg = "Unexpected ASGI message '%s' sent, after response already completed."
raise RuntimeError(msg % message_type)
async def receive(self):
if self.waiting_for_100_continue and not self.transport.is_closing():
self.transport.write(b"HTTP/1.1 100 Continue\r\n\r\n")
self.waiting_for_100_continue = False
if not self.disconnected and not self.response_complete:
self.flow.resume_reading()
await self.message_event.wait()
self.message_event.clear()
if self.disconnected or self.response_complete:
message = {"type": "http.disconnect"}
else:
message = {
"type": "http.request",
"body": self.body,
"more_body": self.more_body,
}
self.body = b""
return message