/usr/share/pyshared/tlslite/integration/AsyncStateMachine.py is in python-tlslite 0.3.8-1.
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 | """
A state machine for using TLS Lite with asynchronous I/O.
"""
class AsyncStateMachine:
"""
This is an abstract class that's used to integrate TLS Lite with
asyncore and Twisted.
This class signals wantsReadsEvent() and wantsWriteEvent(). When
the underlying socket has become readable or writeable, the event
should be passed to this class by calling inReadEvent() or
inWriteEvent(). This class will then try to read or write through
the socket, and will update its state appropriately.
This class will forward higher-level events to its subclass. For
example, when a complete TLS record has been received,
outReadEvent() will be called with the decrypted data.
"""
def __init__(self):
self._clear()
def _clear(self):
#These store the various asynchronous operations (i.e.
#generators). Only one of them, at most, is ever active at a
#time.
self.handshaker = None
self.closer = None
self.reader = None
self.writer = None
#This stores the result from the last call to the
#currently active operation. If 0 it indicates that the
#operation wants to read, if 1 it indicates that the
#operation wants to write. If None, there is no active
#operation.
self.result = None
def _checkAssert(self, maxActive=1):
#This checks that only one operation, at most, is
#active, and that self.result is set appropriately.
activeOps = 0
if self.handshaker:
activeOps += 1
if self.closer:
activeOps += 1
if self.reader:
activeOps += 1
if self.writer:
activeOps += 1
if self.result == None:
if activeOps != 0:
raise AssertionError()
elif self.result in (0,1):
if activeOps != 1:
raise AssertionError()
else:
raise AssertionError()
if activeOps > maxActive:
raise AssertionError()
def wantsReadEvent(self):
"""If the state machine wants to read.
If an operation is active, this returns whether or not the
operation wants to read from the socket. If an operation is
not active, this returns None.
@rtype: bool or None
@return: If the state machine wants to read.
"""
if self.result != None:
return self.result == 0
return None
def wantsWriteEvent(self):
"""If the state machine wants to write.
If an operation is active, this returns whether or not the
operation wants to write to the socket. If an operation is
not active, this returns None.
@rtype: bool or None
@return: If the state machine wants to write.
"""
if self.result != None:
return self.result == 1
return None
def outConnectEvent(self):
"""Called when a handshake operation completes.
May be overridden in subclass.
"""
pass
def outCloseEvent(self):
"""Called when a close operation completes.
May be overridden in subclass.
"""
pass
def outReadEvent(self, readBuffer):
"""Called when a read operation completes.
May be overridden in subclass."""
pass
def outWriteEvent(self):
"""Called when a write operation completes.
May be overridden in subclass."""
pass
def inReadEvent(self):
"""Tell the state machine it can read from the socket."""
try:
self._checkAssert()
if self.handshaker:
self._doHandshakeOp()
elif self.closer:
self._doCloseOp()
elif self.reader:
self._doReadOp()
elif self.writer:
self._doWriteOp()
else:
self.reader = self.tlsConnection.readAsync(16384)
self._doReadOp()
except:
self._clear()
raise
def inWriteEvent(self):
"""Tell the state machine it can write to the socket."""
try:
self._checkAssert()
if self.handshaker:
self._doHandshakeOp()
elif self.closer:
self._doCloseOp()
elif self.reader:
self._doReadOp()
elif self.writer:
self._doWriteOp()
else:
self.outWriteEvent()
except:
self._clear()
raise
def _doHandshakeOp(self):
try:
self.result = self.handshaker.next()
except StopIteration:
self.handshaker = None
self.result = None
self.outConnectEvent()
def _doCloseOp(self):
try:
self.result = self.closer.next()
except StopIteration:
self.closer = None
self.result = None
self.outCloseEvent()
def _doReadOp(self):
self.result = self.reader.next()
if not self.result in (0,1):
readBuffer = self.result
self.reader = None
self.result = None
self.outReadEvent(readBuffer)
def _doWriteOp(self):
try:
self.result = self.writer.next()
except StopIteration:
self.writer = None
self.result = None
def setHandshakeOp(self, handshaker):
"""Start a handshake operation.
@type handshaker: generator
@param handshaker: A generator created by using one of the
asynchronous handshake functions (i.e. handshakeServerAsync, or
handshakeClientxxx(..., async=True).
"""
try:
self._checkAssert(0)
self.handshaker = handshaker
self._doHandshakeOp()
except:
self._clear()
raise
def setServerHandshakeOp(self, **args):
"""Start a handshake operation.
The arguments passed to this function will be forwarded to
L{tlslite.TLSConnection.TLSConnection.handshakeServerAsync}.
"""
handshaker = self.tlsConnection.handshakeServerAsync(**args)
self.setHandshakeOp(handshaker)
def setCloseOp(self):
"""Start a close operation.
"""
try:
self._checkAssert(0)
self.closer = self.tlsConnection.closeAsync()
self._doCloseOp()
except:
self._clear()
raise
def setWriteOp(self, writeBuffer):
"""Start a write operation.
@type writeBuffer: str
@param writeBuffer: The string to transmit.
"""
try:
self._checkAssert(0)
self.writer = self.tlsConnection.writeAsync(writeBuffer)
self._doWriteOp()
except:
self._clear()
raise
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