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net.py
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net.py
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from urllib.parse import urlsplit, urlunsplit
import urllib.parse
from socketserver import BaseServer
import sys
from ssl import SSLError
from misc import Context
import urllib.request
import http.client
from errno import EPIPE, ENOTCONN, ECONNRESET
from select import select
from contextlib import contextmanager
from streams import DelegateWriter
try: # Python 3.3
ConnectionError
except NameError: # Python < 3.3
ConnectionError = ()
DISCONNECTION_ERRNOS = {EPIPE, ENOTCONN, ECONNRESET}
def url_port(url, scheme, ports):
"""Raises "ValueError" if the URL is not valid"""
parsed = urlsplit(url, scheme=scheme)
if not parsed.hostname:
parsed = urlsplit("//" + url, scheme=scheme)
if not parsed.hostname:
raise ValueError("No host name specified: {0!r}".format(url))
try:
def_port = ports[parsed.scheme]
except LookupError:
raise ValueError("Unhandled scheme: {0}".format(parsed.scheme))
port = parsed.port
if port is None:
port = def_port
path = urlunsplit(("", "", parsed.path, parsed.query, parsed.fragment))
return dict(scheme=parsed.scheme, hostname=parsed.hostname, port=port,
path=path, username=parsed.username, password=parsed.password)
def Url(scheme="", netloc="", path="", params="", query="", fragment=""):
return urllib.parse.ParseResult(
scheme, netloc, path, params, query, fragment)
def url_replace(url,
scheme=None, netloc=None, path=None, params=None, query=None, fragment=None):
res = list()
mods = (scheme, netloc, path, params, query, fragment)
for [orig, part] in zip(url, mods):
if part is None:
part = orig
res.append(part)
return urllib.parse.urlunparse(res)
def format_addr(address):
[address, port] = address
if not frozenset("[]:").isdisjoint(address):
address = "[{}]".format(address)
if port is not None:
address = "{}:{}".format(address, port)
return address
def parse_addr(address, defport=None):
address = Url(netloc=address)
host = address.hostname
if host is None:
host = ""
port = address.port
if port is None:
port = defport
return (host, port)
def header_list(message, header):
for header in message.get_all(header, ()):
yield from header_split(header, ",")
class HeaderParams(dict):
def __init__(self, params):
dict.__init__(self)
for param in header_split(params, ";"):
[param, value] = header_partition(param, "=")
param = param.strip().lower()
self.setdefault(param, list()).append(value.strip())
def __missing__(*pos, **kw):
return ()
def get_single(self, name):
value = self[name]
if not value:
raise KeyError("Missing {!r} parameter".format(name))
if len(value) > 1:
raise ValueError("Multiple {!r} parameters".format(name))
[value] = value
return value
def header_split(header, delim):
while header:
[elem, header] = header_partition(header, delim)
if elem:
yield elem
def header_partition(header, sep):
sentinelled = header + sep + '"\\'
pos = 0
while True: # For each quoted segment
end = sentinelled.index(sep, pos)
quote = sentinelled.index('"', pos)
if end < quote:
break
pos = quote + 1
while True: # For each backslash escape in quote
quote = sentinelled.index('"', pos)
backslash = sentinelled.index("\\", pos)
if quote < backslash:
break
pos = min(backslash + 2, len(header))
pos = min(quote + 1, len(header))
return (header[:end].strip(), header[end + 1:].strip())
def header_unquote(header):
segments = list()
while header: # For each quoted segment
[unquoted, _, header] = header.partition('"')
segments.append(unquoted)
sentinelled = header + '"\\'
start = 0
pos = 0
while True: # For each backslash escape in quote
quote = sentinelled.index('"', pos)
backslash = sentinelled.index("\\", pos)
if quote < backslash:
break
segments.append(header[start:backslash])
start = min(backslash + 1, len(header))
pos = min(start + 2, len(header))
segments.append(header[start:quote])
header = header[quote + 1:]
return "".join(segments)
class Server(BaseServer, Context):
default_port = 0
def __init__(self, address=("", None), RequestHandlerClass=None):
[host, port] = address
if port is None:
port = self.default_port
super().__init__((host, port), RequestHandlerClass)
def close(self):
return self.server_close()
def handle_error(self, request, client_address):
[_, exc, *_] = sys.exc_info()
if isinstance(exc, ConnectionError):
return
if (isinstance(exc, SSLError) and
exc.reason == "TLSV1_ALERT_UNKNOWN_CA"):
return
if not isinstance(exc, Exception):
self.close_request(request)
raise # Force server loop to exit
super().handle_error(request, client_address)
class PersistentConnectionHandler(urllib.request.BaseHandler):
"""URL handler for HTTP persistent connections
with PersistentConnectionHandler(timeout=10) as handler:
opener = urllib.request.build_opener(handler)
# First request opens connection
with opener.open("http://localhost/one") as response:
response.read()
# Subsequent requests reuse existing connection, unless it got closed
with opener.open("http://localhost/two") as response:
response.read()
# Closes old connection when new host specified
with opener.open("http://example/three") as response:
response.read()
# Socket freed at context manager exit
Currently does not reuse an existing connection if
two host names happen to resolve to the same Internet address.
"""
conn_classes = {
"http": http.client.HTTPConnection,
"https": http.client.HTTPSConnection,
}
def __init__(self, *pos, **kw):
self._type = None
self._host = None
self._pos = pos
self._kw = kw
self._connection = None
def default_open(self, req):
if req.type not in self.conn_classes:
return None
with self._setup_request(req):
headers = dict(req.header_items())
# On a fresh connection, only attempt request once
response = self._reuse_connection(req, headers)
if not response:
# (Re)try request on a fresh connection
self._attempt_request(req, headers)
response = self._connection.getresponse()
# Odd impedance mismatch between "http.client" and "urllib.request"
response.msg = response.reason
return response
def start_request(self, request):
with self._setup_request(request):
self._check_reusable()
self._connection.putrequest(
request.get_method(), request.selector)
for item in request.header_items():
self._connection.putheader(*item)
self._connection.endheaders()
def get_writer(self):
return DelegateWriter(self._connection.send)
def get_response(self):
response = self._connection.getresponse()
response.msg.set_default_type(None)
return response
@contextmanager
def _setup_request(self, req):
if req.type != self._type or req.host != self._host:
if self._connection:
self._connection.close()
conn_class = self.conn_classes[req.type]
self._connection = conn_class(req.host, *self._pos, **self._kw)
self._type = req.type
self._host = req.host
try:
yield
except:
self._connection.close() # Allow caller to make more requests
raise
def _check_reusable(self):
if self._connection.sock is None:
return False
if any(select((self._connection.sock,), (), (), 0)):
# Assume EOF or 408 Request Timeout has been signalled
self._connection.close()
return False
return True
def _reuse_connection(self, req, headers):
if not self._check_reusable():
return None
# Attempt request on existing connection
self._attempt_request(req, headers)
try:
try:
response = self._connection.getresponse()
except EnvironmentError as err: # Python < 3.3 compat.
if err.errno not in DISCONNECTION_ERRNOS:
raise
raise http.client.BadStatusLine(err) from err
except (ConnectionError, http.client.BadStatusLine):
idempotents = {
"GET", "HEAD", "PUT", "DELETE", "TRACE", "OPTIONS"}
if req.get_method() not in idempotents:
raise
self._connection.close()
return None # Retry requests whose method indicates idempotence
if response.status == http.client.REQUEST_TIMEOUT:
# Server indicated it did not handle request
return None
return response
def _attempt_request(self, req, headers):
"""Send HTTP request, ignoring broken pipe and similar errors"""
try:
self._connection.request(req.get_method(), req.selector,
req.data, headers)
except (ConnectionRefusedError, ConnectionAbortedError):
raise # Assume connection was not established
except ConnectionError:
pass # Continue and read server response if available
except EnvironmentError as err: # Python < 3.3 compatibility
if err.errno not in DISCONNECTION_ERRNOS:
raise
def close(self):
if self._connection:
self._connection.close()
def __enter__(self):
return self
def __exit__(self, *exc):
self.close()
def http_request(url, types=None, *,
urlopen=urllib.request.urlopen, headers=(), **kw):
headers = dict(headers)
if types is not None:
headers["Accept"] = ", ".join(types)
req = urllib.request.Request(url, headers=headers, **kw)
response = urlopen(req)
try:
headers = response.info()
[type, _] = headers.get_params([(None, None)])[0]
if types is not None and type not in types:
msg = "Unexpected content type {}"
raise TypeError(msg.format(type))
return response
except:
response.close()
raise