Source code for tornado.iostream

#!/usr/bin/env python
#
# Copyright 2009 Facebook
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.

"""Utility classes to write to and read from non-blocking files and sockets.

Contents:

* `BaseIOStream`: Generic interface for reading and writing.
* `IOStream`: Implementation of BaseIOStream using non-blocking sockets.
* `SSLIOStream`: SSL-aware version of IOStream.
* `PipeIOStream`: Pipe-based IOStream implementation.
"""

from __future__ import absolute_import, division, print_function, with_statement

import collections
import errno
import numbers
import os
import socket
import ssl
import sys
import re

from tornado import ioloop
from tornado.log import gen_log, app_log
from tornado.netutil import ssl_wrap_socket, ssl_match_hostname, SSLCertificateError
from tornado import stack_context
from tornado.util import bytes_type

try:
    from tornado.platform.posix import _set_nonblocking
except ImportError:
    _set_nonblocking = None


[docs]class StreamClosedError(IOError): """Exception raised by `IOStream` methods when the stream is closed. Note that the close callback is scheduled to run *after* other callbacks on the stream (to allow for buffered data to be processed), so you may see this error before you see the close callback. """ pass
[docs]class BaseIOStream(object): """A utility class to write to and read from a non-blocking file or socket. We support a non-blocking ``write()`` and a family of ``read_*()`` methods. All of the methods take callbacks (since writing and reading are non-blocking and asynchronous). When a stream is closed due to an error, the IOStream's ``error`` attribute contains the exception object. Subclasses must implement `fileno`, `close_fd`, `write_to_fd`, `read_from_fd`, and optionally `get_fd_error`. """ def __init__(self, io_loop=None, max_buffer_size=None, read_chunk_size=4096): self.io_loop = io_loop or ioloop.IOLoop.current() self.max_buffer_size = max_buffer_size or 104857600 self.read_chunk_size = read_chunk_size self.error = None self._read_buffer = collections.deque() self._write_buffer = collections.deque() self._read_buffer_size = 0 self._write_buffer_frozen = False self._read_delimiter = None self._read_regex = None self._read_bytes = None self._read_until_close = False self._read_callback = None self._streaming_callback = None self._write_callback = None self._close_callback = None self._connect_callback = None self._connecting = False self._state = None self._pending_callbacks = 0 self._closed = False
[docs] def fileno(self): """Returns the file descriptor for this stream.""" raise NotImplementedError()
[docs] def close_fd(self): """Closes the file underlying this stream. ``close_fd`` is called by `BaseIOStream` and should not be called elsewhere; other users should call `close` instead. """ raise NotImplementedError()
[docs] def write_to_fd(self, data): """Attempts to write ``data`` to the underlying file. Returns the number of bytes written. """ raise NotImplementedError()
[docs] def read_from_fd(self): """Attempts to read from the underlying file. Returns ``None`` if there was nothing to read (the socket returned `~errno.EWOULDBLOCK` or equivalent), otherwise returns the data. When possible, should return no more than ``self.read_chunk_size`` bytes at a time. """ raise NotImplementedError()
[docs] def get_fd_error(self): """Returns information about any error on the underlying file. This method is called after the `.IOLoop` has signaled an error on the file descriptor, and should return an Exception (such as `socket.error` with additional information, or None if no such information is available. """ return None
[docs] def read_until_regex(self, regex, callback): """Run ``callback`` when we read the given regex pattern. The callback will get the data read (including the data that matched the regex and anything that came before it) as an argument. """ self._set_read_callback(callback) self._read_regex = re.compile(regex) self._try_inline_read()
[docs] def read_until(self, delimiter, callback): """Run ``callback`` when we read the given delimiter. The callback will get the data read (including the delimiter) as an argument. """ self._set_read_callback(callback) self._read_delimiter = delimiter self._try_inline_read()
[docs] def read_bytes(self, num_bytes, callback, streaming_callback=None): """Run callback when we read the given number of bytes. If a ``streaming_callback`` is given, it will be called with chunks of data as they become available, and the argument to the final ``callback`` will be empty. Otherwise, the ``callback`` gets the data as an argument. """ self._set_read_callback(callback) assert isinstance(num_bytes, numbers.Integral) self._read_bytes = num_bytes self._streaming_callback = stack_context.wrap(streaming_callback) self._try_inline_read()
[docs] def read_until_close(self, callback, streaming_callback=None): """Reads all data from the socket until it is closed. If a ``streaming_callback`` is given, it will be called with chunks of data as they become available, and the argument to the final ``callback`` will be empty. Otherwise, the ``callback`` gets the data as an argument. Subject to ``max_buffer_size`` limit from `IOStream` constructor if a ``streaming_callback`` is not used. """ self._set_read_callback(callback) self._streaming_callback = stack_context.wrap(streaming_callback) if self.closed(): if self._streaming_callback is not None: self._run_callback(self._streaming_callback, self._consume(self._read_buffer_size)) self._run_callback(self._read_callback, self._consume(self._read_buffer_size)) self._streaming_callback = None self._read_callback = None return self._read_until_close = True self._streaming_callback = stack_context.wrap(streaming_callback) self._try_inline_read()
[docs] def write(self, data, callback=None): """Write the given data to this stream. If ``callback`` is given, we call it when all of the buffered write data has been successfully written to the stream. If there was previously buffered write data and an old write callback, that callback is simply overwritten with this new callback. """ assert isinstance(data, bytes_type) self._check_closed() # We use bool(_write_buffer) as a proxy for write_buffer_size>0, # so never put empty strings in the buffer. if data: # Break up large contiguous strings before inserting them in the # write buffer, so we don't have to recopy the entire thing # as we slice off pieces to send to the socket. WRITE_BUFFER_CHUNK_SIZE = 128 * 1024 if len(data) > WRITE_BUFFER_CHUNK_SIZE: for i in range(0, len(data), WRITE_BUFFER_CHUNK_SIZE): self._write_buffer.append(data[i:i + WRITE_BUFFER_CHUNK_SIZE]) else: self._write_buffer.append(data) self._write_callback = stack_context.wrap(callback) if not self._connecting: self._handle_write() if self._write_buffer: self._add_io_state(self.io_loop.WRITE) self._maybe_add_error_listener()
[docs] def set_close_callback(self, callback): """Call the given callback when the stream is closed.""" self._close_callback = stack_context.wrap(callback)
[docs] def close(self, exc_info=False): """Close this stream. If ``exc_info`` is true, set the ``error`` attribute to the current exception from `sys.exc_info` (or if ``exc_info`` is a tuple, use that instead of `sys.exc_info`). """ if not self.closed(): if exc_info: if not isinstance(exc_info, tuple): exc_info = sys.exc_info() if any(exc_info): self.error = exc_info[1] if self._read_until_close: if (self._streaming_callback is not None and self._read_buffer_size): self._run_callback(self._streaming_callback, self._consume(self._read_buffer_size)) callback = self._read_callback self._read_callback = None self._read_until_close = False self._run_callback(callback, self._consume(self._read_buffer_size)) if self._state is not None: self.io_loop.remove_handler(self.fileno()) self._state = None self.close_fd() self._closed = True self._maybe_run_close_callback()
def _maybe_run_close_callback(self): if (self.closed() and self._close_callback and self._pending_callbacks == 0): # if there are pending callbacks, don't run the close callback # until they're done (see _maybe_add_error_handler) cb = self._close_callback self._close_callback = None self._run_callback(cb) # Delete any unfinished callbacks to break up reference cycles. self._read_callback = self._write_callback = None
[docs] def reading(self): """Returns true if we are currently reading from the stream.""" return self._read_callback is not None
[docs] def writing(self): """Returns true if we are currently writing to the stream.""" return bool(self._write_buffer)
[docs] def closed(self): """Returns true if the stream has been closed.""" return self._closed
[docs] def set_nodelay(self, value): """Sets the no-delay flag for this stream. By default, data written to TCP streams may be held for a time to make the most efficient use of bandwidth (according to Nagle's algorithm). The no-delay flag requests that data be written as soon as possible, even if doing so would consume additional bandwidth. This flag is currently defined only for TCP-based ``IOStreams``. .. versionadded:: 3.1 """ pass
def _handle_events(self, fd, events): if self.closed(): gen_log.warning("Got events for closed stream %d", fd) return try: if events & self.io_loop.READ: self._handle_read() if self.closed(): return if events & self.io_loop.WRITE: if self._connecting: self._handle_connect() self._handle_write() if self.closed(): return if events & self.io_loop.ERROR: self.error = self.get_fd_error() # We may have queued up a user callback in _handle_read or # _handle_write, so don't close the IOStream until those # callbacks have had a chance to run. self.io_loop.add_callback(self.close) return state = self.io_loop.ERROR if self.reading(): state |= self.io_loop.READ if self.writing(): state |= self.io_loop.WRITE if state == self.io_loop.ERROR: state |= self.io_loop.READ if state != self._state: assert self._state is not None, \ "shouldn't happen: _handle_events without self._state" self._state = state self.io_loop.update_handler(self.fileno(), self._state) except Exception: gen_log.error("Uncaught exception, closing connection.", exc_info=True) self.close(exc_info=True) raise def _run_callback(self, callback, *args): def wrapper(): self._pending_callbacks -= 1 try: callback(*args) except Exception: app_log.error("Uncaught exception, closing connection.", exc_info=True) # Close the socket on an uncaught exception from a user callback # (It would eventually get closed when the socket object is # gc'd, but we don't want to rely on gc happening before we # run out of file descriptors) self.close(exc_info=True) # Re-raise the exception so that IOLoop.handle_callback_exception # can see it and log the error raise self._maybe_add_error_listener() # We schedule callbacks to be run on the next IOLoop iteration # rather than running them directly for several reasons: # * Prevents unbounded stack growth when a callback calls an # IOLoop operation that immediately runs another callback # * Provides a predictable execution context for e.g. # non-reentrant mutexes # * Ensures that the try/except in wrapper() is run outside # of the application's StackContexts with stack_context.NullContext(): # stack_context was already captured in callback, we don't need to # capture it again for IOStream's wrapper. This is especially # important if the callback was pre-wrapped before entry to # IOStream (as in HTTPConnection._header_callback), as we could # capture and leak the wrong context here. self._pending_callbacks += 1 self.io_loop.add_callback(wrapper) def _handle_read(self): try: try: # Pretend to have a pending callback so that an EOF in # _read_to_buffer doesn't trigger an immediate close # callback. At the end of this method we'll either # estabilsh a real pending callback via # _read_from_buffer or run the close callback. # # We need two try statements here so that # pending_callbacks is decremented before the `except` # clause below (which calls `close` and does need to # trigger the callback) self._pending_callbacks += 1 while not self.closed(): # Read from the socket until we get EWOULDBLOCK or equivalent. # SSL sockets do some internal buffering, and if the data is # sitting in the SSL object's buffer select() and friends # can't see it; the only way to find out if it's there is to # try to read it. if self._read_to_buffer() == 0: break finally: self._pending_callbacks -= 1 except Exception: gen_log.warning("error on read", exc_info=True) self.close(exc_info=True) return if self._read_from_buffer(): return else: self._maybe_run_close_callback() def _set_read_callback(self, callback): assert not self._read_callback, "Already reading" self._read_callback = stack_context.wrap(callback) def _try_inline_read(self): """Attempt to complete the current read operation from buffered data. If the read can be completed without blocking, schedules the read callback on the next IOLoop iteration; otherwise starts listening for reads on the socket. """ # See if we've already got the data from a previous read if self._read_from_buffer(): return self._check_closed() try: try: # See comments in _handle_read about incrementing _pending_callbacks self._pending_callbacks += 1 while not self.closed(): if self._read_to_buffer() == 0: break finally: self._pending_callbacks -= 1 except Exception: # If there was an in _read_to_buffer, we called close() already, # but couldn't run the close callback because of _pending_callbacks. # Before we escape from this function, run the close callback if # applicable. self._maybe_run_close_callback() raise if self._read_from_buffer(): return self._maybe_add_error_listener() def _read_to_buffer(self): """Reads from the socket and appends the result to the read buffer. Returns the number of bytes read. Returns 0 if there is nothing to read (i.e. the read returns EWOULDBLOCK or equivalent). On error closes the socket and raises an exception. """ try: chunk = self.read_from_fd() except (socket.error, IOError, OSError) as e: # ssl.SSLError is a subclass of socket.error if e.args[0] == errno.ECONNRESET: # Treat ECONNRESET as a connection close rather than # an error to minimize log spam (the exception will # be available on self.error for apps that care). self.close(exc_info=True) return self.close(exc_info=True) raise if chunk is None: return 0 self._read_buffer.append(chunk) self._read_buffer_size += len(chunk) if self._read_buffer_size >= self.max_buffer_size: gen_log.error("Reached maximum read buffer size") self.close() raise IOError("Reached maximum read buffer size") return len(chunk) def _read_from_buffer(self): """Attempts to complete the currently-pending read from the buffer. Returns True if the read was completed. """ if self._streaming_callback is not None and self._read_buffer_size: bytes_to_consume = self._read_buffer_size if self._read_bytes is not None: bytes_to_consume = min(self._read_bytes, bytes_to_consume) self._read_bytes -= bytes_to_consume self._run_callback(self._streaming_callback, self._consume(bytes_to_consume)) if self._read_bytes is not None and self._read_buffer_size >= self._read_bytes: num_bytes = self._read_bytes callback = self._read_callback self._read_callback = None self._streaming_callback = None self._read_bytes = None self._run_callback(callback, self._consume(num_bytes)) return True elif self._read_delimiter is not None: # Multi-byte delimiters (e.g. '\r\n') may straddle two # chunks in the read buffer, so we can't easily find them # without collapsing the buffer. However, since protocols # using delimited reads (as opposed to reads of a known # length) tend to be "line" oriented, the delimiter is likely # to be in the first few chunks. Merge the buffer gradually # since large merges are relatively expensive and get undone in # consume(). if self._read_buffer: while True: loc = self._read_buffer[0].find(self._read_delimiter) if loc != -1: callback = self._read_callback delimiter_len = len(self._read_delimiter) self._read_callback = None self._streaming_callback = None self._read_delimiter = None self._run_callback(callback, self._consume(loc + delimiter_len)) return True if len(self._read_buffer) == 1: break _double_prefix(self._read_buffer) elif self._read_regex is not None: if self._read_buffer: while True: m = self._read_regex.search(self._read_buffer[0]) if m is not None: callback = self._read_callback self._read_callback = None self._streaming_callback = None self._read_regex = None self._run_callback(callback, self._consume(m.end())) return True if len(self._read_buffer) == 1: break _double_prefix(self._read_buffer) return False def _handle_write(self): while self._write_buffer: try: if not self._write_buffer_frozen: # On windows, socket.send blows up if given a # write buffer that's too large, instead of just # returning the number of bytes it was able to # process. Therefore we must not call socket.send # with more than 128KB at a time. _merge_prefix(self._write_buffer, 128 * 1024) num_bytes = self.write_to_fd(self._write_buffer[0]) if num_bytes == 0: # With OpenSSL, if we couldn't write the entire buffer, # the very same string object must be used on the # next call to send. Therefore we suppress # merging the write buffer after an incomplete send. # A cleaner solution would be to set # SSL_MODE_ACCEPT_MOVING_WRITE_BUFFER, but this is # not yet accessible from python # (http://bugs.python.org/issue8240) self._write_buffer_frozen = True break self._write_buffer_frozen = False _merge_prefix(self._write_buffer, num_bytes) self._write_buffer.popleft() except socket.error as e: if e.args[0] in (errno.EWOULDBLOCK, errno.EAGAIN): self._write_buffer_frozen = True break else: if e.args[0] not in (errno.EPIPE, errno.ECONNRESET): # Broken pipe errors are usually caused by connection # reset, and its better to not log EPIPE errors to # minimize log spam gen_log.warning("Write error on %d: %s", self.fileno(), e) self.close(exc_info=True) return if not self._write_buffer and self._write_callback: callback = self._write_callback self._write_callback = None self._run_callback(callback) def _consume(self, loc): if loc == 0: return b"" _merge_prefix(self._read_buffer, loc) self._read_buffer_size -= loc return self._read_buffer.popleft() def _check_closed(self): if self.closed(): raise StreamClosedError("Stream is closed") def _maybe_add_error_listener(self): if self._state is None and self._pending_callbacks == 0: if self.closed(): self._maybe_run_close_callback() else: self._add_io_state(ioloop.IOLoop.READ) def _add_io_state(self, state): """Adds `state` (IOLoop.{READ,WRITE} flags) to our event handler. Implementation notes: Reads and writes have a fast path and a slow path. The fast path reads synchronously from socket buffers, while the slow path uses `_add_io_state` to schedule an IOLoop callback. Note that in both cases, the callback is run asynchronously with `_run_callback`. To detect closed connections, we must have called `_add_io_state` at some point, but we want to delay this as much as possible so we don't have to set an `IOLoop.ERROR` listener that will be overwritten by the next slow-path operation. As long as there are callbacks scheduled for fast-path ops, those callbacks may do more reads. If a sequence of fast-path ops do not end in a slow-path op, (e.g. for an @asynchronous long-poll request), we must add the error handler. This is done in `_run_callback` and `write` (since the write callback is optional so we can have a fast-path write with no `_run_callback`) """ if self.closed(): # connection has been closed, so there can be no future events return if self._state is None: self._state = ioloop.IOLoop.ERROR | state with stack_context.NullContext(): self.io_loop.add_handler( self.fileno(), self._handle_events, self._state) elif not self._state & state: self._state = self._state | state self.io_loop.update_handler(self.fileno(), self._state)
[docs]class IOStream(BaseIOStream): r"""Socket-based `IOStream` implementation. This class supports the read and write methods from `BaseIOStream` plus a `connect` method. The ``socket`` parameter may either be connected or unconnected. For server operations the socket is the result of calling `socket.accept <socket.socket.accept>`. For client operations the socket is created with `socket.socket`, and may either be connected before passing it to the `IOStream` or connected with `IOStream.connect`. A very simple (and broken) HTTP client using this class:: import tornado.ioloop import tornado.iostream import socket def send_request(): stream.write(b"GET / HTTP/1.0\r\nHost: friendfeed.com\r\n\r\n") stream.read_until(b"\r\n\r\n", on_headers) def on_headers(data): headers = {} for line in data.split(b"\r\n"): parts = line.split(b":") if len(parts) == 2: headers[parts[0].strip()] = parts[1].strip() stream.read_bytes(int(headers[b"Content-Length"]), on_body) def on_body(data): print data stream.close() tornado.ioloop.IOLoop.instance().stop() s = socket.socket(socket.AF_INET, socket.SOCK_STREAM, 0) stream = tornado.iostream.IOStream(s) stream.connect(("friendfeed.com", 80), send_request) tornado.ioloop.IOLoop.instance().start() """ def __init__(self, socket, *args, **kwargs): self.socket = socket self.socket.setblocking(False) super(IOStream, self).__init__(*args, **kwargs) def fileno(self): return self.socket.fileno() def close_fd(self): self.socket.close() self.socket = None def get_fd_error(self): errno = self.socket.getsockopt(socket.SOL_SOCKET, socket.SO_ERROR) return socket.error(errno, os.strerror(errno)) def read_from_fd(self): try: chunk = self.socket.recv(self.read_chunk_size) except socket.error as e: if e.args[0] in (errno.EWOULDBLOCK, errno.EAGAIN): return None else: raise if not chunk: self.close() return None return chunk def write_to_fd(self, data): return self.socket.send(data)
[docs] def connect(self, address, callback=None, server_hostname=None): """Connects the socket to a remote address without blocking. May only be called if the socket passed to the constructor was not previously connected. The address parameter is in the same format as for `socket.connect <socket.socket.connect>`, i.e. a ``(host, port)`` tuple. If ``callback`` is specified, it will be called when the connection is completed. If specified, the ``server_hostname`` parameter will be used in SSL connections for certificate validation (if requested in the ``ssl_options``) and SNI (if supported; requires Python 3.2+). Note that it is safe to call `IOStream.write <BaseIOStream.write>` while the connection is pending, in which case the data will be written as soon as the connection is ready. Calling `IOStream` read methods before the socket is connected works on some platforms but is non-portable. """ self._connecting = True try: self.socket.connect(address) except socket.error as e: # In non-blocking mode we expect connect() to raise an # exception with EINPROGRESS or EWOULDBLOCK. # # On freebsd, other errors such as ECONNREFUSED may be # returned immediately when attempting to connect to # localhost, so handle them the same way as an error # reported later in _handle_connect. if e.args[0] not in (errno.EINPROGRESS, errno.EWOULDBLOCK): gen_log.warning("Connect error on fd %d: %s", self.socket.fileno(), e) self.close(exc_info=True) return self._connect_callback = stack_context.wrap(callback) self._add_io_state(self.io_loop.WRITE)
def _handle_connect(self): err = self.socket.getsockopt(socket.SOL_SOCKET, socket.SO_ERROR) if err != 0: self.error = socket.error(err, os.strerror(err)) # IOLoop implementations may vary: some of them return # an error state before the socket becomes writable, so # in that case a connection failure would be handled by the # error path in _handle_events instead of here. gen_log.warning("Connect error on fd %d: %s", self.socket.fileno(), errno.errorcode[err]) self.close() return if self._connect_callback is not None: callback = self._connect_callback self._connect_callback = None self._run_callback(callback) self._connecting = False def set_nodelay(self, value): if (self.socket is not None and self.socket.family in (socket.AF_INET, socket.AF_INET6)): try: self.socket.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1 if value else 0) except socket.error as e: # Sometimes setsockopt will fail if the socket is closed # at the wrong time. This can happen with HTTPServer # resetting the value to false between requests. if e.errno != errno.EINVAL: raise
[docs]class SSLIOStream(IOStream): """A utility class to write to and read from a non-blocking SSL socket. If the socket passed to the constructor is already connected, it should be wrapped with:: ssl.wrap_socket(sock, do_handshake_on_connect=False, **kwargs) before constructing the `SSLIOStream`. Unconnected sockets will be wrapped when `IOStream.connect` is finished. """ def __init__(self, *args, **kwargs): """The ``ssl_options`` keyword argument may either be a dictionary of keywords arguments for `ssl.wrap_socket`, or an `ssl.SSLContext` object. """ self._ssl_options = kwargs.pop('ssl_options', {}) super(SSLIOStream, self).__init__(*args, **kwargs) self._ssl_accepting = True self._handshake_reading = False self._handshake_writing = False self._ssl_connect_callback = None self._server_hostname = None def reading(self): return self._handshake_reading or super(SSLIOStream, self).reading() def writing(self): return self._handshake_writing or super(SSLIOStream, self).writing() def _do_ssl_handshake(self): # Based on code from test_ssl.py in the python stdlib try: self._handshake_reading = False self._handshake_writing = False self.socket.do_handshake() except ssl.SSLError as err: if err.args[0] == ssl.SSL_ERROR_WANT_READ: self._handshake_reading = True return elif err.args[0] == ssl.SSL_ERROR_WANT_WRITE: self._handshake_writing = True return elif err.args[0] in (ssl.SSL_ERROR_EOF, ssl.SSL_ERROR_ZERO_RETURN): return self.close(exc_info=True) elif err.args[0] == ssl.SSL_ERROR_SSL: try: peer = self.socket.getpeername() except Exception: peer = '(not connected)' gen_log.warning("SSL Error on %d %s: %s", self.socket.fileno(), peer, err) return self.close(exc_info=True) raise except socket.error as err: if err.args[0] in (errno.ECONNABORTED, errno.ECONNRESET): return self.close(exc_info=True) except AttributeError: # On Linux, if the connection was reset before the call to # wrap_socket, do_handshake will fail with an # AttributeError. return self.close(exc_info=True) else: self._ssl_accepting = False if not self._verify_cert(self.socket.getpeercert()): self.close() return if self._ssl_connect_callback is not None: callback = self._ssl_connect_callback self._ssl_connect_callback = None self._run_callback(callback) def _verify_cert(self, peercert): """Returns True if peercert is valid according to the configured validation mode and hostname. The ssl handshake already tested the certificate for a valid CA signature; the only thing that remains is to check the hostname. """ if isinstance(self._ssl_options, dict): verify_mode = self._ssl_options.get('cert_reqs', ssl.CERT_NONE) elif isinstance(self._ssl_options, ssl.SSLContext): verify_mode = self._ssl_options.verify_mode assert verify_mode in (ssl.CERT_NONE, ssl.CERT_REQUIRED, ssl.CERT_OPTIONAL) if verify_mode == ssl.CERT_NONE or self._server_hostname is None: return True cert = self.socket.getpeercert() if cert is None and verify_mode == ssl.CERT_REQUIRED: gen_log.warning("No SSL certificate given") return False try: ssl_match_hostname(peercert, self._server_hostname) except SSLCertificateError: gen_log.warning("Invalid SSL certificate", exc_info=True) return False else: return True def _handle_read(self): if self._ssl_accepting: self._do_ssl_handshake() return super(SSLIOStream, self)._handle_read() def _handle_write(self): if self._ssl_accepting: self._do_ssl_handshake() return super(SSLIOStream, self)._handle_write() def connect(self, address, callback=None, server_hostname=None): # Save the user's callback and run it after the ssl handshake # has completed. self._ssl_connect_callback = stack_context.wrap(callback) self._server_hostname = server_hostname super(SSLIOStream, self).connect(address, callback=None) def _handle_connect(self): # When the connection is complete, wrap the socket for SSL # traffic. Note that we do this by overriding _handle_connect # instead of by passing a callback to super().connect because # user callbacks are enqueued asynchronously on the IOLoop, # but since _handle_events calls _handle_connect immediately # followed by _handle_write we need this to be synchronous. self.socket = ssl_wrap_socket(self.socket, self._ssl_options, server_hostname=self._server_hostname, do_handshake_on_connect=False) super(SSLIOStream, self)._handle_connect() def read_from_fd(self): if self._ssl_accepting: # If the handshake hasn't finished yet, there can't be anything # to read (attempting to read may or may not raise an exception # depending on the SSL version) return None try: # SSLSocket objects have both a read() and recv() method, # while regular sockets only have recv(). # The recv() method blocks (at least in python 2.6) if it is # called when there is nothing to read, so we have to use # read() instead. chunk = self.socket.read(self.read_chunk_size) except ssl.SSLError as e: # SSLError is a subclass of socket.error, so this except # block must come first. if e.args[0] == ssl.SSL_ERROR_WANT_READ: return None else: raise except socket.error as e: if e.args[0] in (errno.EWOULDBLOCK, errno.EAGAIN): return None else: raise if not chunk: self.close() return None return chunk
[docs]class PipeIOStream(BaseIOStream): """Pipe-based `IOStream` implementation. The constructor takes an integer file descriptor (such as one returned by `os.pipe`) rather than an open file object. Pipes are generally one-way, so a `PipeIOStream` can be used for reading or writing but not both. """ def __init__(self, fd, *args, **kwargs): self.fd = fd _set_nonblocking(fd) super(PipeIOStream, self).__init__(*args, **kwargs) def fileno(self): return self.fd def close_fd(self): os.close(self.fd) def write_to_fd(self, data): return os.write(self.fd, data) def read_from_fd(self): try: chunk = os.read(self.fd, self.read_chunk_size) except (IOError, OSError) as e: if e.args[0] in (errno.EWOULDBLOCK, errno.EAGAIN): return None elif e.args[0] == errno.EBADF: # If the writing half of a pipe is closed, select will # report it as readable but reads will fail with EBADF. self.close(exc_info=True) return None else: raise if not chunk: self.close() return None return chunk
def _double_prefix(deque): """Grow by doubling, but don't split the second chunk just because the first one is small. """ new_len = max(len(deque[0]) * 2, (len(deque[0]) + len(deque[1]))) _merge_prefix(deque, new_len) def _merge_prefix(deque, size): """Replace the first entries in a deque of strings with a single string of up to size bytes. >>> d = collections.deque(['abc', 'de', 'fghi', 'j']) >>> _merge_prefix(d, 5); print(d) deque(['abcde', 'fghi', 'j']) Strings will be split as necessary to reach the desired size. >>> _merge_prefix(d, 7); print(d) deque(['abcdefg', 'hi', 'j']) >>> _merge_prefix(d, 3); print(d) deque(['abc', 'defg', 'hi', 'j']) >>> _merge_prefix(d, 100); print(d) deque(['abcdefghij']) """ if len(deque) == 1 and len(deque[0]) <= size: return prefix = [] remaining = size while deque and remaining > 0: chunk = deque.popleft() if len(chunk) > remaining: deque.appendleft(chunk[remaining:]) chunk = chunk[:remaining] prefix.append(chunk) remaining -= len(chunk) # This data structure normally just contains byte strings, but # the unittest gets messy if it doesn't use the default str() type, # so do the merge based on the type of data that's actually present. if prefix: deque.appendleft(type(prefix[0])().join(prefix)) if not deque: deque.appendleft(b"") def doctests(): import doctest return doctest.DocTestSuite()

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