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
|
"""
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
|