/usr/lib/python3/dist-packages/twisted/protocols/basic.py is in python3-twisted-experimental 13.2.0-0ubuntu1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 | # -*- test-case-name: twisted.protocols.test.test_basic -*-
# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.
"""
Basic protocols, such as line-oriented, netstring, and int prefixed strings.
"""
from __future__ import absolute_import, division
# System imports
import re
from struct import pack, unpack, calcsize
from io import BytesIO
import math
from zope.interface import implementer
# Twisted imports
from twisted.python.compat import _PY3
from twisted.internet import protocol, defer, interfaces, error
from twisted.python import log
# Unfortunately we cannot use regular string formatting on Python 3; see
# http://bugs.python.org/issue3982 for details.
if _PY3:
def _formatNetstring(data):
return b''.join([str(len(data)).encode("ascii"), b':', data, b','])
else:
def _formatNetstring(data):
return b'%d:%s,' % (len(data), data)
_formatNetstring.__doc__ = """
Convert some C{bytes} into netstring format.
@param data: C{bytes} that will be reformatted.
"""
DEBUG = 0
class NetstringParseError(ValueError):
"""
The incoming data is not in valid Netstring format.
"""
class IncompleteNetstring(Exception):
"""
Not enough data to complete a netstring.
"""
class NetstringReceiver(protocol.Protocol):
"""
A protocol that sends and receives netstrings.
See U{http://cr.yp.to/proto/netstrings.txt} for the specification of
netstrings. Every netstring starts with digits that specify the length
of the data. This length specification is separated from the data by
a colon. The data is terminated with a comma.
Override L{stringReceived} to handle received netstrings. This
method is called with the netstring payload as a single argument
whenever a complete netstring is received.
Security features:
1. Messages are limited in size, useful if you don't want
someone sending you a 500MB netstring (change C{self.MAX_LENGTH}
to the maximum length you wish to accept).
2. The connection is lost if an illegal message is received.
@ivar MAX_LENGTH: Defines the maximum length of netstrings that can be
received.
@type MAX_LENGTH: C{int}
@ivar _LENGTH: A pattern describing all strings that contain a netstring
length specification. Examples for length specifications are C{b'0:'},
C{b'12:'}, and C{b'179:'}. C{b'007:'} is not a valid length
specification, since leading zeros are not allowed.
@type _LENGTH: C{re.Match}
@ivar _LENGTH_PREFIX: A pattern describing all strings that contain
the first part of a netstring length specification (without the
trailing comma). Examples are '0', '12', and '179'. '007' does not
start a netstring length specification, since leading zeros are
not allowed.
@type _LENGTH_PREFIX: C{re.Match}
@ivar _PARSING_LENGTH: Indicates that the C{NetstringReceiver} is in
the state of parsing the length portion of a netstring.
@type _PARSING_LENGTH: C{int}
@ivar _PARSING_PAYLOAD: Indicates that the C{NetstringReceiver} is in
the state of parsing the payload portion (data and trailing comma)
of a netstring.
@type _PARSING_PAYLOAD: C{int}
@ivar brokenPeer: Indicates if the connection is still functional
@type brokenPeer: C{int}
@ivar _state: Indicates if the protocol is consuming the length portion
(C{PARSING_LENGTH}) or the payload (C{PARSING_PAYLOAD}) of a netstring
@type _state: C{int}
@ivar _remainingData: Holds the chunk of data that has not yet been consumed
@type _remainingData: C{string}
@ivar _payload: Holds the payload portion of a netstring including the
trailing comma
@type _payload: C{BytesIO}
@ivar _expectedPayloadSize: Holds the payload size plus one for the trailing
comma.
@type _expectedPayloadSize: C{int}
"""
MAX_LENGTH = 99999
_LENGTH = re.compile(b'(0|[1-9]\d*)(:)')
_LENGTH_PREFIX = re.compile(b'(0|[1-9]\d*)$')
# Some error information for NetstringParseError instances.
_MISSING_LENGTH = ("The received netstring does not start with a "
"length specification.")
_OVERFLOW = ("The length specification of the received netstring "
"cannot be represented in Python - it causes an "
"OverflowError!")
_TOO_LONG = ("The received netstring is longer than the maximum %s "
"specified by self.MAX_LENGTH")
_MISSING_COMMA = "The received netstring is not terminated by a comma."
# The following constants are used for determining if the NetstringReceiver
# is parsing the length portion of a netstring, or the payload.
_PARSING_LENGTH, _PARSING_PAYLOAD = range(2)
def makeConnection(self, transport):
"""
Initializes the protocol.
"""
protocol.Protocol.makeConnection(self, transport)
self._remainingData = b""
self._currentPayloadSize = 0
self._payload = BytesIO()
self._state = self._PARSING_LENGTH
self._expectedPayloadSize = 0
self.brokenPeer = 0
def sendString(self, string):
"""
Sends a netstring.
Wraps up C{string} by adding length information and a
trailing comma; writes the result to the transport.
@param string: The string to send. The necessary framing (length
prefix, etc) will be added.
@type string: C{bytes}
"""
self.transport.write(_formatNetstring(string))
def dataReceived(self, data):
"""
Receives some characters of a netstring.
Whenever a complete netstring is received, this method extracts
its payload and calls L{stringReceived} to process it.
@param data: A chunk of data representing a (possibly partial)
netstring
@type data: C{bytes}
"""
self._remainingData += data
while self._remainingData:
try:
self._consumeData()
except IncompleteNetstring:
break
except NetstringParseError:
self._handleParseError()
break
def stringReceived(self, string):
"""
Override this for notification when each complete string is received.
@param string: The complete string which was received with all
framing (length prefix, etc) removed.
@type string: C{bytes}
@raise NotImplementedError: because the method has to be implemented
by the child class.
"""
raise NotImplementedError()
def _maxLengthSize(self):
"""
Calculate and return the string size of C{self.MAX_LENGTH}.
@return: The size of the string representation for C{self.MAX_LENGTH}
@rtype: C{float}
"""
return math.ceil(math.log10(self.MAX_LENGTH)) + 1
def _consumeData(self):
"""
Consumes the content of C{self._remainingData}.
@raise IncompleteNetstring: if C{self._remainingData} does not
contain enough data to complete the current netstring.
@raise NetstringParseError: if the received data do not
form a valid netstring.
"""
if self._state == self._PARSING_LENGTH:
self._consumeLength()
self._prepareForPayloadConsumption()
if self._state == self._PARSING_PAYLOAD:
self._consumePayload()
def _consumeLength(self):
"""
Consumes the length portion of C{self._remainingData}.
@raise IncompleteNetstring: if C{self._remainingData} contains
a partial length specification (digits without trailing
comma).
@raise NetstringParseError: if the received data do not form a valid
netstring.
"""
lengthMatch = self._LENGTH.match(self._remainingData)
if not lengthMatch:
self._checkPartialLengthSpecification()
raise IncompleteNetstring()
self._processLength(lengthMatch)
def _checkPartialLengthSpecification(self):
"""
Makes sure that the received data represents a valid number.
Checks if C{self._remainingData} represents a number smaller or
equal to C{self.MAX_LENGTH}.
@raise NetstringParseError: if C{self._remainingData} is no
number or is too big (checked by L{extractLength}).
"""
partialLengthMatch = self._LENGTH_PREFIX.match(self._remainingData)
if not partialLengthMatch:
raise NetstringParseError(self._MISSING_LENGTH)
lengthSpecification = (partialLengthMatch.group(1))
self._extractLength(lengthSpecification)
def _processLength(self, lengthMatch):
"""
Processes the length definition of a netstring.
Extracts and stores in C{self._expectedPayloadSize} the number
representing the netstring size. Removes the prefix
representing the length specification from
C{self._remainingData}.
@raise NetstringParseError: if the received netstring does not
start with a number or the number is bigger than
C{self.MAX_LENGTH}.
@param lengthMatch: A regular expression match object matching
a netstring length specification
@type lengthMatch: C{re.Match}
"""
endOfNumber = lengthMatch.end(1)
startOfData = lengthMatch.end(2)
lengthString = self._remainingData[:endOfNumber]
# Expect payload plus trailing comma:
self._expectedPayloadSize = self._extractLength(lengthString) + 1
self._remainingData = self._remainingData[startOfData:]
def _extractLength(self, lengthAsString):
"""
Attempts to extract the length information of a netstring.
@raise NetstringParseError: if the number is bigger than
C{self.MAX_LENGTH}.
@param lengthAsString: A chunk of data starting with a length
specification
@type lengthAsString: C{bytes}
@return: The length of the netstring
@rtype: C{int}
"""
self._checkStringSize(lengthAsString)
length = int(lengthAsString)
if length > self.MAX_LENGTH:
raise NetstringParseError(self._TOO_LONG % (self.MAX_LENGTH,))
return length
def _checkStringSize(self, lengthAsString):
"""
Checks the sanity of lengthAsString.
Checks if the size of the length specification exceeds the
size of the string representing self.MAX_LENGTH. If this is
not the case, the number represented by lengthAsString is
certainly bigger than self.MAX_LENGTH, and a
NetstringParseError can be raised.
This method should make sure that netstrings with extremely
long length specifications are refused before even attempting
to convert them to an integer (which might trigger a
MemoryError).
"""
if len(lengthAsString) > self._maxLengthSize():
raise NetstringParseError(self._TOO_LONG % (self.MAX_LENGTH,))
def _prepareForPayloadConsumption(self):
"""
Sets up variables necessary for consuming the payload of a netstring.
"""
self._state = self._PARSING_PAYLOAD
self._currentPayloadSize = 0
self._payload.seek(0)
self._payload.truncate()
def _consumePayload(self):
"""
Consumes the payload portion of C{self._remainingData}.
If the payload is complete, checks for the trailing comma and
processes the payload. If not, raises an L{IncompleteNetstring}
exception.
@raise IncompleteNetstring: if the payload received so far
contains fewer characters than expected.
@raise NetstringParseError: if the payload does not end with a
comma.
"""
self._extractPayload()
if self._currentPayloadSize < self._expectedPayloadSize:
raise IncompleteNetstring()
self._checkForTrailingComma()
self._state = self._PARSING_LENGTH
self._processPayload()
def _extractPayload(self):
"""
Extracts payload information from C{self._remainingData}.
Splits C{self._remainingData} at the end of the netstring. The
first part becomes C{self._payload}, the second part is stored
in C{self._remainingData}.
If the netstring is not yet complete, the whole content of
C{self._remainingData} is moved to C{self._payload}.
"""
if self._payloadComplete():
remainingPayloadSize = (self._expectedPayloadSize -
self._currentPayloadSize)
self._payload.write(self._remainingData[:remainingPayloadSize])
self._remainingData = self._remainingData[remainingPayloadSize:]
self._currentPayloadSize = self._expectedPayloadSize
else:
self._payload.write(self._remainingData)
self._currentPayloadSize += len(self._remainingData)
self._remainingData = b""
def _payloadComplete(self):
"""
Checks if enough data have been received to complete the netstring.
@return: C{True} iff the received data contain at least as many
characters as specified in the length section of the
netstring
@rtype: C{bool}
"""
return (len(self._remainingData) + self._currentPayloadSize >=
self._expectedPayloadSize)
def _processPayload(self):
"""
Processes the actual payload with L{stringReceived}.
Strips C{self._payload} of the trailing comma and calls
L{stringReceived} with the result.
"""
self.stringReceived(self._payload.getvalue()[:-1])
def _checkForTrailingComma(self):
"""
Checks if the netstring has a trailing comma at the expected position.
@raise NetstringParseError: if the last payload character is
anything but a comma.
"""
if self._payload.getvalue()[-1:] != b",":
raise NetstringParseError(self._MISSING_COMMA)
def _handleParseError(self):
"""
Terminates the connection and sets the flag C{self.brokenPeer}.
"""
self.transport.loseConnection()
self.brokenPeer = 1
class LineOnlyReceiver(protocol.Protocol):
"""
A protocol that receives only lines.
This is purely a speed optimisation over LineReceiver, for the
cases that raw mode is known to be unnecessary.
@cvar delimiter: The line-ending delimiter to use. By default this is
C{b'\\r\\n'}.
@cvar MAX_LENGTH: The maximum length of a line to allow (If a
sent line is longer than this, the connection is dropped).
Default is 16384.
"""
_buffer = b''
delimiter = b'\r\n'
MAX_LENGTH = 16384
def dataReceived(self, data):
"""
Translates bytes into lines, and calls lineReceived.
"""
lines = (self._buffer+data).split(self.delimiter)
self._buffer = lines.pop(-1)
for line in lines:
if self.transport.disconnecting:
# this is necessary because the transport may be told to lose
# the connection by a line within a larger packet, and it is
# important to disregard all the lines in that packet following
# the one that told it to close.
return
if len(line) > self.MAX_LENGTH:
return self.lineLengthExceeded(line)
else:
self.lineReceived(line)
if len(self._buffer) > self.MAX_LENGTH:
return self.lineLengthExceeded(self._buffer)
def lineReceived(self, line):
"""
Override this for when each line is received.
@param line: The line which was received with the delimiter removed.
@type line: C{bytes}
"""
raise NotImplementedError
def sendLine(self, line):
"""
Sends a line to the other end of the connection.
@param line: The line to send, not including the delimiter.
@type line: C{bytes}
"""
return self.transport.writeSequence((line, self.delimiter))
def lineLengthExceeded(self, line):
"""
Called when the maximum line length has been reached.
Override if it needs to be dealt with in some special way.
"""
return error.ConnectionLost('Line length exceeded')
class _PauseableMixin:
paused = False
def pauseProducing(self):
self.paused = True
self.transport.pauseProducing()
def resumeProducing(self):
self.paused = False
self.transport.resumeProducing()
self.dataReceived(b'')
def stopProducing(self):
self.paused = True
self.transport.stopProducing()
class LineReceiver(protocol.Protocol, _PauseableMixin):
"""
A protocol that receives lines and/or raw data, depending on mode.
In line mode, each line that's received becomes a callback to
L{lineReceived}. In raw data mode, each chunk of raw data becomes a
callback to L{rawDataReceived}. The L{setLineMode} and L{setRawMode}
methods switch between the two modes.
This is useful for line-oriented protocols such as IRC, HTTP, POP, etc.
@cvar delimiter: The line-ending delimiter to use. By default this is
C{b'\\r\\n'}.
@cvar MAX_LENGTH: The maximum length of a line to allow (If a
sent line is longer than this, the connection is dropped).
Default is 16384.
"""
line_mode = 1
_buffer = b''
_busyReceiving = False
delimiter = b'\r\n'
MAX_LENGTH = 16384
def clearLineBuffer(self):
"""
Clear buffered data.
@return: All of the cleared buffered data.
@rtype: C{bytes}
"""
b, self._buffer = self._buffer, b""
return b
def dataReceived(self, data):
"""
Protocol.dataReceived.
Translates bytes into lines, and calls lineReceived (or
rawDataReceived, depending on mode.)
"""
if self._busyReceiving:
self._buffer += data
return
try:
self._busyReceiving = True
self._buffer += data
while self._buffer and not self.paused:
if self.line_mode:
try:
line, self._buffer = self._buffer.split(
self.delimiter, 1)
except ValueError:
if len(self._buffer) > self.MAX_LENGTH:
line, self._buffer = self._buffer, b''
return self.lineLengthExceeded(line)
return
else:
lineLength = len(line)
if lineLength > self.MAX_LENGTH:
exceeded = line + self.delimiter + self._buffer
self._buffer = b''
return self.lineLengthExceeded(exceeded)
why = self.lineReceived(line)
if (why or self.transport and
self.transport.disconnecting):
return why
else:
data = self._buffer
self._buffer = b''
why = self.rawDataReceived(data)
if why:
return why
finally:
self._busyReceiving = False
def setLineMode(self, extra=b''):
"""
Sets the line-mode of this receiver.
If you are calling this from a rawDataReceived callback,
you can pass in extra unhandled data, and that data will
be parsed for lines. Further data received will be sent
to lineReceived rather than rawDataReceived.
Do not pass extra data if calling this function from
within a lineReceived callback.
"""
self.line_mode = 1
if extra:
return self.dataReceived(extra)
def setRawMode(self):
"""
Sets the raw mode of this receiver.
Further data received will be sent to rawDataReceived rather
than lineReceived.
"""
self.line_mode = 0
def rawDataReceived(self, data):
"""
Override this for when raw data is received.
"""
raise NotImplementedError
def lineReceived(self, line):
"""
Override this for when each line is received.
@param line: The line which was received with the delimiter removed.
@type line: C{bytes}
"""
raise NotImplementedError
def sendLine(self, line):
"""
Sends a line to the other end of the connection.
@param line: The line to send, not including the delimiter.
@type line: C{bytes}
"""
return self.transport.write(line + self.delimiter)
def lineLengthExceeded(self, line):
"""
Called when the maximum line length has been reached.
Override if it needs to be dealt with in some special way.
The argument 'line' contains the remainder of the buffer, starting
with (at least some part) of the line which is too long. This may
be more than one line, or may be only the initial portion of the
line.
"""
return self.transport.loseConnection()
class StringTooLongError(AssertionError):
"""
Raised when trying to send a string too long for a length prefixed
protocol.
"""
class _RecvdCompatHack(object):
"""
Emulates the to-be-deprecated C{IntNStringReceiver.recvd} attribute.
The C{recvd} attribute was where the working buffer for buffering and
parsing netstrings was kept. It was updated each time new data arrived and
each time some of that data was parsed and delivered to application code.
The piecemeal updates to its string value were expensive and have been
removed from C{IntNStringReceiver} in the normal case. However, for
applications directly reading this attribute, this descriptor restores that
behavior. It only copies the working buffer when necessary (ie, when
accessed). This avoids the cost for applications not using the data.
This is a custom descriptor rather than a property, because we still need
the default __set__ behavior in both new-style and old-style subclasses.
"""
def __get__(self, oself, type=None):
return oself._unprocessed[oself._compatibilityOffset:]
class IntNStringReceiver(protocol.Protocol, _PauseableMixin):
"""
Generic class for length prefixed protocols.
@ivar _unprocessed: bytes received, but not yet broken up into messages /
sent to stringReceived. _compatibilityOffset must be updated when this
value is updated so that the C{recvd} attribute can be generated
correctly.
@type _unprocessed: C{bytes}
@ivar structFormat: format used for struct packing/unpacking. Define it in
subclass.
@type structFormat: C{str}
@ivar prefixLength: length of the prefix, in bytes. Define it in subclass,
using C{struct.calcsize(structFormat)}
@type prefixLength: C{int}
@ivar _compatibilityOffset: the offset within C{_unprocessed} to the next
message to be parsed. (used to generate the recvd attribute)
@type _compatibilityOffset: C{int}
"""
MAX_LENGTH = 99999
_unprocessed = b""
_compatibilityOffset = 0
# Backwards compatibility support for applications which directly touch the
# "internal" parse buffer.
recvd = _RecvdCompatHack()
def stringReceived(self, string):
"""
Override this for notification when each complete string is received.
@param string: The complete string which was received with all
framing (length prefix, etc) removed.
@type string: C{bytes}
"""
raise NotImplementedError
def lengthLimitExceeded(self, length):
"""
Callback invoked when a length prefix greater than C{MAX_LENGTH} is
received. The default implementation disconnects the transport.
Override this.
@param length: The length prefix which was received.
@type length: C{int}
"""
self.transport.loseConnection()
def dataReceived(self, data):
"""
Convert int prefixed strings into calls to stringReceived.
"""
# Try to minimize string copying (via slices) by keeping one buffer
# containing all the data we have so far and a separate offset into that
# buffer.
alldata = self._unprocessed + data
currentOffset = 0
prefixLength = self.prefixLength
fmt = self.structFormat
self._unprocessed = alldata
while len(alldata) >= (currentOffset + prefixLength) and not self.paused:
messageStart = currentOffset + prefixLength
length, = unpack(fmt, alldata[currentOffset:messageStart])
if length > self.MAX_LENGTH:
self._unprocessed = alldata
self._compatibilityOffset = currentOffset
self.lengthLimitExceeded(length)
return
messageEnd = messageStart + length
if len(alldata) < messageEnd:
break
# Here we have to slice the working buffer so we can send just the
# netstring into the stringReceived callback.
packet = alldata[messageStart:messageEnd]
currentOffset = messageEnd
self._compatibilityOffset = currentOffset
self.stringReceived(packet)
# Check to see if the backwards compat "recvd" attribute got written
# to by application code. If so, drop the current data buffer and
# switch to the new buffer given by that attribute's value.
if 'recvd' in self.__dict__:
alldata = self.__dict__.pop('recvd')
self._unprocessed = alldata
self._compatibilityOffset = currentOffset = 0
if alldata:
continue
return
# Slice off all the data that has been processed, avoiding holding onto
# memory to store it, and update the compatibility attributes to reflect
# that change.
self._unprocessed = alldata[currentOffset:]
self._compatibilityOffset = 0
def sendString(self, string):
"""
Send a prefixed string to the other end of the connection.
@param string: The string to send. The necessary framing (length
prefix, etc) will be added.
@type string: C{bytes}
"""
if len(string) >= 2 ** (8 * self.prefixLength):
raise StringTooLongError(
"Try to send %s bytes whereas maximum is %s" % (
len(string), 2 ** (8 * self.prefixLength)))
self.transport.write(
pack(self.structFormat, len(string)) + string)
class Int32StringReceiver(IntNStringReceiver):
"""
A receiver for int32-prefixed strings.
An int32 string is a string prefixed by 4 bytes, the 32-bit length of
the string encoded in network byte order.
This class publishes the same interface as NetstringReceiver.
"""
structFormat = "!I"
prefixLength = calcsize(structFormat)
class Int16StringReceiver(IntNStringReceiver):
"""
A receiver for int16-prefixed strings.
An int16 string is a string prefixed by 2 bytes, the 16-bit length of
the string encoded in network byte order.
This class publishes the same interface as NetstringReceiver.
"""
structFormat = "!H"
prefixLength = calcsize(structFormat)
class Int8StringReceiver(IntNStringReceiver):
"""
A receiver for int8-prefixed strings.
An int8 string is a string prefixed by 1 byte, the 8-bit length of
the string.
This class publishes the same interface as NetstringReceiver.
"""
structFormat = "!B"
prefixLength = calcsize(structFormat)
class StatefulStringProtocol:
"""
A stateful string protocol.
This is a mixin for string protocols (L{Int32StringReceiver},
L{NetstringReceiver}) which translates L{stringReceived} into a callback
(prefixed with C{'proto_'}) depending on state.
The state C{'done'} is special; if a C{proto_*} method returns it, the
connection will be closed immediately.
@ivar state: Current state of the protocol. Defaults to C{'init'}.
@type state: C{str}
"""
state = 'init'
def stringReceived(self, string):
"""
Choose a protocol phase function and call it.
Call back to the appropriate protocol phase; this begins with
the function C{proto_init} and moves on to C{proto_*} depending on
what each C{proto_*} function returns. (For example, if
C{self.proto_init} returns 'foo', then C{self.proto_foo} will be the
next function called when a protocol message is received.
"""
try:
pto = 'proto_' + self.state
statehandler = getattr(self, pto)
except AttributeError:
log.msg('callback', self.state, 'not found')
else:
self.state = statehandler(string)
if self.state == 'done':
self.transport.loseConnection()
@implementer(interfaces.IProducer)
class FileSender:
"""
A producer that sends the contents of a file to a consumer.
This is a helper for protocols that, at some point, will take a
file-like object, read its contents, and write them out to the network,
optionally performing some transformation on the bytes in between.
"""
CHUNK_SIZE = 2 ** 14
lastSent = ''
deferred = None
def beginFileTransfer(self, file, consumer, transform=None):
"""
Begin transferring a file
@type file: Any file-like object
@param file: The file object to read data from
@type consumer: Any implementor of IConsumer
@param consumer: The object to write data to
@param transform: A callable taking one string argument and returning
the same. All bytes read from the file are passed through this before
being written to the consumer.
@rtype: C{Deferred}
@return: A deferred whose callback will be invoked when the file has
been completely written to the consumer. The last byte written to the
consumer is passed to the callback.
"""
self.file = file
self.consumer = consumer
self.transform = transform
self.deferred = deferred = defer.Deferred()
self.consumer.registerProducer(self, False)
return deferred
def resumeProducing(self):
chunk = ''
if self.file:
chunk = self.file.read(self.CHUNK_SIZE)
if not chunk:
self.file = None
self.consumer.unregisterProducer()
if self.deferred:
self.deferred.callback(self.lastSent)
self.deferred = None
return
if self.transform:
chunk = self.transform(chunk)
self.consumer.write(chunk)
self.lastSent = chunk[-1:]
def pauseProducing(self):
pass
def stopProducing(self):
if self.deferred:
self.deferred.errback(
Exception("Consumer asked us to stop producing"))
self.deferred = None
|