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# -*- coding: utf-8 -*-
"""
gevent-server.py
================
A simple HTTP/2 server written for gevent serving static files from a directory specified as input.
If no directory is provided, the current directory will be used.
"""
import mimetypes
import sys
from functools import partial
from pathlib import Path
from typing import Tuple, Dict, Optional
from gevent import socket, ssl
from gevent.event import Event
from gevent.server import StreamServer
from h2 import events
from h2.config import H2Configuration
from h2.connection import H2Connection
def get_http2_tls_context() -> ssl.SSLContext:
ctx = ssl.create_default_context(purpose=ssl.Purpose.CLIENT_AUTH)
ctx.options |= (
ssl.OP_NO_SSLv2 | ssl.OP_NO_SSLv3 | ssl.OP_NO_TLSv1 | ssl.OP_NO_TLSv1_1
)
ctx.options |= ssl.OP_NO_COMPRESSION
ctx.set_ciphers('ECDHE+AESGCM:ECDHE+CHACHA20:DHE+AESGCM:DHE+CHACHA20')
ctx.load_cert_chain(certfile='localhost.crt', keyfile='localhost.key')
ctx.set_alpn_protocols(['h2'])
try:
ctx.set_npn_protocols(['h2'])
except NotImplementedError:
pass
return ctx
class H2Worker:
def __init__(self, sock: socket, address: Tuple[str, str], source_dir: str = None):
self._sock = sock
self._address = address
self._flow_control_events: Dict[int, Event] = {}
self._server_name = 'gevent-h2'
self._connection: Optional[H2Connection] = None
self._read_chunk_size = 8192 # The maximum amount of a file we'll send in a single DATA frame
self._check_sources_dir(source_dir)
self._sources_dir = source_dir
self._run()
def _initiate_connection(self):
config = H2Configuration(client_side=False, header_encoding='utf-8')
self._connection = H2Connection(config=config)
self._connection.initiate_connection()
self._sock.sendall(self._connection.data_to_send())
@staticmethod
def _check_sources_dir(sources_dir: str) -> None:
p = Path(sources_dir)
if not p.is_dir():
raise NotADirectoryError(f'{sources_dir} does not exists')
def _send_error_response(self, status_code: str, event: events.RequestReceived) -> None:
self._connection.send_headers(
stream_id=event.stream_id,
headers=[
(':status', status_code),
('content-length', '0'),
('server', self._server_name),
],
end_stream=True
)
self._sock.sendall(self._connection.data_to_send())
def _handle_request(self, event: events.RequestReceived) -> None:
headers = dict(event.headers)
if headers[':method'] != 'GET':
self._send_error_response('405', event)
return
file_path = Path(self._sources_dir) / headers[':path'].lstrip('/')
if not file_path.is_file():
self._send_error_response('404', event)
return
self._send_file(file_path, event.stream_id)
def _send_file(self, file_path: Path, stream_id: int) -> None:
"""
Send a file, obeying the rules of HTTP/2 flow control.
"""
file_size = file_path.stat().st_size
content_type, content_encoding = mimetypes.guess_type(str(file_path))
response_headers = [
(':status', '200'),
('content-length', str(file_size)),
('server', self._server_name)
]
if content_type:
response_headers.append(('content-type', content_type))
if content_encoding:
response_headers.append(('content-encoding', content_encoding))
self._connection.send_headers(stream_id, response_headers)
self._sock.sendall(self._connection.data_to_send())
with file_path.open(mode='rb', buffering=0) as f:
self._send_file_data(f, stream_id)
def _send_file_data(self, file_obj, stream_id: int) -> None:
"""
Send the data portion of a file. Handles flow control rules.
"""
while True:
while self._connection.local_flow_control_window(stream_id) < 1:
self._wait_for_flow_control(stream_id)
chunk_size = min(self._connection.local_flow_control_window(stream_id), self._read_chunk_size)
data = file_obj.read(chunk_size)
keep_reading = (len(data) == chunk_size)
self._connection.send_data(stream_id, data, not keep_reading)
self._sock.sendall(self._connection.data_to_send())
if not keep_reading:
break
def _wait_for_flow_control(self, stream_id: int) -> None:
"""
Blocks until the flow control window for a given stream is opened.
"""
event = Event()
self._flow_control_events[stream_id] = event
event.wait()
def _handle_window_update(self, event: events.WindowUpdated) -> None:
"""
Unblock streams waiting on flow control, if needed.
"""
stream_id = event.stream_id
if stream_id and stream_id in self._flow_control_events:
g_event = self._flow_control_events.pop(stream_id)
g_event.set()
elif not stream_id:
# Need to keep a real list here to use only the events present at this time.
blocked_streams = list(self._flow_control_events.keys())
for stream_id in blocked_streams:
g_event = self._flow_control_events.pop(stream_id)
g_event.set()
def _run(self) -> None:
self._initiate_connection()
while True:
data = self._sock.recv(65535)
if not data:
break
h2_events = self._connection.receive_data(data)
for event in h2_events:
if isinstance(event, events.RequestReceived):
self._handle_request(event)
elif isinstance(event, events.DataReceived):
self._connection.reset_stream(event.stream_id)
elif isinstance(event, events.WindowUpdated):
self._handle_window_update(event)
data_to_send = self._connection.data_to_send()
if data_to_send:
self._sock.sendall(data_to_send)
if __name__ == '__main__':
files_dir = sys.argv[1] if len(sys.argv) > 1 else f'{Path().cwd()}'
server = StreamServer(('127.0.0.1', 8080), partial(H2Worker, source_dir=files_dir),
ssl_context=get_http2_tls_context())
try:
server.serve_forever()
except KeyboardInterrupt:
server.close()