"""Helper class for TLSConnection.""" from __future__ import generators from utils.compat import * from utils.cryptomath import * from utils.cipherfactory import createAES, createRC4, createTripleDES from utils.codec import * from errors import * from messages import * from mathtls import * from constants import * from utils.cryptomath import getRandomBytes from utils import hmac from FileObject import FileObject import sha import md5 import socket import errno import traceback try: GeneratorExit except NameError: class GeneratorExit(Exception): pass class _ConnectionState: def __init__(self): self.macContext = None self.encContext = None self.seqnum = 0 def getSeqNumStr(self): w = Writer(8) w.add(self.seqnum, 8) seqnumStr = bytesToString(w.bytes) self.seqnum += 1 return seqnumStr class TLSRecordLayer: """ This class handles data transmission for a TLS connection. Its only subclass is L{tlslite.TLSConnection.TLSConnection}. We've separated the code in this class from TLSConnection to make things more readable. @type sock: socket.socket @ivar sock: The underlying socket object. @type session: L{tlslite.Session.Session} @ivar session: The session corresponding to this connection. Due to TLS session resumption, multiple connections can correspond to the same underlying session. @type version: tuple @ivar version: The TLS version being used for this connection. (3,0) means SSL 3.0, and (3,1) means TLS 1.0. @type closed: bool @ivar closed: If this connection is closed. @type resumed: bool @ivar resumed: If this connection is based on a resumed session. @type allegedSharedKeyUsername: str or None @ivar allegedSharedKeyUsername: This is set to the shared-key username asserted by the client, whether the handshake succeeded or not. If the handshake fails, this can be inspected to determine if a guessing attack is in progress against a particular user account. @type allegedSrpUsername: str or None @ivar allegedSrpUsername: This is set to the SRP username asserted by the client, whether the handshake succeeded or not. If the handshake fails, this can be inspected to determine if a guessing attack is in progress against a particular user account. @type closeSocket: bool @ivar closeSocket: If the socket should be closed when the connection is closed (writable). If you set this to True, TLS Lite will assume the responsibility of closing the socket when the TLS Connection is shutdown (either through an error or through the user calling close()). The default is False. @type ignoreAbruptClose: bool @ivar ignoreAbruptClose: If an abrupt close of the socket should raise an error (writable). If you set this to True, TLS Lite will not raise a L{tlslite.errors.TLSAbruptCloseError} exception if the underlying socket is unexpectedly closed. Such an unexpected closure could be caused by an attacker. However, it also occurs with some incorrect TLS implementations. You should set this to True only if you're not worried about an attacker truncating the connection, and only if necessary to avoid spurious errors. The default is False. @sort: __init__, read, readAsync, write, writeAsync, close, closeAsync, getCipherImplementation, getCipherName """ def __init__(self, sock): self.sock = sock #My session object (Session instance; read-only) self.session = None #Am I a client or server? self._client = None #Buffers for processing messages self._handshakeBuffer = [] self._readBuffer = "" #Handshake digests self._handshake_md5 = md5.md5() self._handshake_sha = sha.sha() #TLS Protocol Version self.version = (0,0) #read-only self._versionCheck = False #Once we choose a version, this is True #Current and Pending connection states self._writeState = _ConnectionState() self._readState = _ConnectionState() self._pendingWriteState = _ConnectionState() self._pendingReadState = _ConnectionState() #Is the connection open? self.closed = True #read-only self._refCount = 0 #Used to trigger closure #Is this a resumed (or shared-key) session? self.resumed = False #read-only #What username did the client claim in his handshake? self.allegedSharedKeyUsername = None self.allegedSrpUsername = None #On a call to close(), do we close the socket? (writeable) self.closeSocket = False #If the socket is abruptly closed, do we ignore it #and pretend the connection was shut down properly? (writeable) self.ignoreAbruptClose = False #Fault we will induce, for testing purposes self.fault = None #********************************************************* # Public Functions START #********************************************************* def read(self, max=None, min=1): """Read some data from the TLS connection. This function will block until at least 'min' bytes are available (or the connection is closed). If an exception is raised, the connection will have been automatically closed. @type max: int @param max: The maximum number of bytes to return. @type min: int @param min: The minimum number of bytes to return @rtype: str @return: A string of no more than 'max' bytes, and no fewer than 'min' (unless the connection has been closed, in which case fewer than 'min' bytes may be returned). @raise socket.error: If a socket error occurs. @raise tlslite.errors.TLSAbruptCloseError: If the socket is closed without a preceding alert. @raise tlslite.errors.TLSAlert: If a TLS alert is signalled. """ for result in self.readAsync(max, min): pass return result def readAsync(self, max=None, min=1): """Start a read operation on the TLS connection. This function returns a generator which behaves similarly to read(). Successive invocations of the generator will return 0 if it is waiting to read from the socket, 1 if it is waiting to write to the socket, or a string if the read operation has completed. @rtype: iterable @return: A generator; see above for details. """ try: while len(self._readBuffer)= len(s): break if endIndex > len(s): endIndex = len(s) block = stringToBytes(s[startIndex : endIndex]) applicationData = ApplicationData().create(block) for result in self._sendMsg(applicationData, skipEmptyFrag): yield result skipEmptyFrag = True #only send an empy fragment on 1st message index += 1 except: self._shutdown(False) raise def close(self): """Close the TLS connection. This function will block until it has exchanged close_notify alerts with the other party. After doing so, it will shut down the TLS connection. Further attempts to read through this connection will return "". Further attempts to write through this connection will raise ValueError. If makefile() has been called on this connection, the connection will be not be closed until the connection object and all file objects have been closed. Even if an exception is raised, the connection will have been closed. @raise socket.error: If a socket error occurs. @raise tlslite.errors.TLSAbruptCloseError: If the socket is closed without a preceding alert. @raise tlslite.errors.TLSAlert: If a TLS alert is signalled. """ if not self.closed: for result in self._decrefAsync(): pass def closeAsync(self): """Start a close operation on the TLS connection. This function returns a generator which behaves similarly to close(). Successive invocations of the generator will return 0 if it is waiting to read from the socket, 1 if it is waiting to write to the socket, or will raise StopIteration if the close operation has completed. @rtype: iterable @return: A generator; see above for details. """ if not self.closed: for result in self._decrefAsync(): yield result def _decrefAsync(self): self._refCount -= 1 if self._refCount == 0 and not self.closed: try: for result in self._sendMsg(Alert().create(\ AlertDescription.close_notify, AlertLevel.warning)): yield result alert = None while not alert: for result in self._getMsg((ContentType.alert, \ ContentType.application_data)): if result in (0,1): yield result if result.contentType == ContentType.alert: alert = result if alert.description == AlertDescription.close_notify: self._shutdown(True) else: raise TLSRemoteAlert(alert) except (socket.error, TLSAbruptCloseError): #If the other side closes the socket, that's okay self._shutdown(True) except: self._shutdown(False) raise def getCipherName(self): """Get the name of the cipher used with this connection. @rtype: str @return: The name of the cipher used with this connection. Either 'aes128', 'aes256', 'rc4', or '3des'. """ if not self._writeState.encContext: return None return self._writeState.encContext.name def getCipherImplementation(self): """Get the name of the cipher implementation used with this connection. @rtype: str @return: The name of the cipher implementation used with this connection. Either 'python', 'cryptlib', 'openssl', or 'pycrypto'. """ if not self._writeState.encContext: return None return self._writeState.encContext.implementation #Emulate a socket, somewhat - def send(self, s): """Send data to the TLS connection (socket emulation). @raise socket.error: If a socket error occurs. """ self.write(s) return len(s) def sendall(self, s): """Send data to the TLS connection (socket emulation). @raise socket.error: If a socket error occurs. """ self.write(s) def recv(self, bufsize): """Get some data from the TLS connection (socket emulation). @raise socket.error: If a socket error occurs. @raise tlslite.errors.TLSAbruptCloseError: If the socket is closed without a preceding alert. @raise tlslite.errors.TLSAlert: If a TLS alert is signalled. """ return self.read(bufsize) def makefile(self, mode='r', bufsize=-1): """Create a file object for the TLS connection (socket emulation). @rtype: L{tlslite.FileObject.FileObject} """ self._refCount += 1 return FileObject(self, mode, bufsize) def getsockname(self): """Return the socket's own address (socket emulation).""" return self.sock.getsockname() def getpeername(self): """Return the remote address to which the socket is connected (socket emulation).""" return self.sock.getpeername() def settimeout(self, value): """Set a timeout on blocking socket operations (socket emulation).""" return self.sock.settimeout(value) def gettimeout(self): """Return the timeout associated with socket operations (socket emulation).""" return self.sock.gettimeout() def setsockopt(self, level, optname, value): """Set the value of the given socket option (socket emulation).""" return self.sock.setsockopt(level, optname, value) #********************************************************* # Public Functions END #********************************************************* def _shutdown(self, resumable): self._writeState = _ConnectionState() self._readState = _ConnectionState() #Don't do this: self._readBuffer = "" self.version = (0,0) self._versionCheck = False self.closed = True if self.closeSocket: self.sock.close() #Even if resumable is False, we'll never toggle this on if not resumable and self.session: self.session.resumable = False def _sendError(self, alertDescription, errorStr=None): alert = Alert().create(alertDescription, AlertLevel.fatal) for result in self._sendMsg(alert): yield result self._shutdown(False) raise TLSLocalAlert(alert, errorStr) def _sendMsgs(self, msgs): skipEmptyFrag = False for msg in msgs: for result in self._sendMsg(msg, skipEmptyFrag): yield result skipEmptyFrag = True def _sendMsg(self, msg, skipEmptyFrag=False): bytes = msg.write() contentType = msg.contentType #Whenever we're connected and asked to send a message, #we first send an empty Application Data message. This prevents #an attacker from launching a chosen-plaintext attack based on #knowing the next IV. if not self.closed and not skipEmptyFrag and self.version == (3,1): if self._writeState.encContext: if self._writeState.encContext.isBlockCipher: for result in self._sendMsg(ApplicationData(), skipEmptyFrag=True): yield result #Update handshake hashes if contentType == ContentType.handshake: bytesStr = bytesToString(bytes) self._handshake_md5.update(bytesStr) self._handshake_sha.update(bytesStr) #Calculate MAC if self._writeState.macContext: seqnumStr = self._writeState.getSeqNumStr() bytesStr = bytesToString(bytes) mac = self._writeState.macContext.copy() mac.update(seqnumStr) mac.update(chr(contentType)) if self.version == (3,0): mac.update( chr( int(len(bytes)/256) ) ) mac.update( chr( int(len(bytes)%256) ) ) elif self.version in ((3,1), (3,2)): mac.update(chr(self.version[0])) mac.update(chr(self.version[1])) mac.update( chr( int(len(bytes)/256) ) ) mac.update( chr( int(len(bytes)%256) ) ) else: raise AssertionError() mac.update(bytesStr) macString = mac.digest() macBytes = stringToBytes(macString) if self.fault == Fault.badMAC: macBytes[0] = (macBytes[0]+1) % 256 #Encrypt for Block or Stream Cipher if self._writeState.encContext: #Add padding and encrypt (for Block Cipher): if self._writeState.encContext.isBlockCipher: #Add TLS 1.1 fixed block if self.version == (3,2): bytes = self.fixedIVBlock + bytes #Add padding: bytes = bytes + (macBytes + paddingBytes) currentLength = len(bytes) + len(macBytes) + 1 blockLength = self._writeState.encContext.block_size paddingLength = blockLength-(currentLength % blockLength) paddingBytes = createByteArraySequence([paddingLength] * \ (paddingLength+1)) if self.fault == Fault.badPadding: paddingBytes[0] = (paddingBytes[0]+1) % 256 endBytes = concatArrays(macBytes, paddingBytes) bytes = concatArrays(bytes, endBytes) #Encrypt plaintext = stringToBytes(bytes) ciphertext = self._writeState.encContext.encrypt(plaintext) bytes = stringToBytes(ciphertext) #Encrypt (for Stream Cipher) else: bytes = concatArrays(bytes, macBytes) plaintext = bytesToString(bytes) ciphertext = self._writeState.encContext.encrypt(plaintext) bytes = stringToBytes(ciphertext) #Add record header and send r = RecordHeader3().create(self.version, contentType, len(bytes)) s = bytesToString(concatArrays(r.write(), bytes)) while 1: try: bytesSent = self.sock.send(s) #Might raise socket.error except socket.error, why: if why[0] == errno.EWOULDBLOCK: yield 1 continue else: raise if bytesSent == len(s): return s = s[bytesSent:] yield 1 def _getMsg(self, expectedType, secondaryType=None, constructorType=None): try: if not isinstance(expectedType, tuple): expectedType = (expectedType,) #Spin in a loop, until we've got a non-empty record of a type we #expect. The loop will be repeated if: # - we receive a renegotiation attempt; we send no_renegotiation, # then try again # - we receive an empty application-data fragment; we try again while 1: for result in self._getNextRecord(): if result in (0,1): yield result recordHeader, p = result #If this is an empty application-data fragment, try again if recordHeader.type == ContentType.application_data: if p.index == len(p.bytes): continue #If we received an unexpected record type... if recordHeader.type not in expectedType: #If we received an alert... if recordHeader.type == ContentType.alert: alert = Alert().parse(p) #We either received a fatal error, a warning, or a #close_notify. In any case, we're going to close the #connection. In the latter two cases we respond with #a close_notify, but ignore any socket errors, since #the other side might have already closed the socket. if alert.level == AlertLevel.warning or \ alert.description == AlertDescription.close_notify: #If the sendMsg() call fails because the socket has #already been closed, we will be forgiving and not #report the error nor invalidate the "resumability" #of the session. try: alertMsg = Alert() alertMsg.create(AlertDescription.close_notify, AlertLevel.warning) for result in self._sendMsg(alertMsg): yield result except socket.error: pass if alert.description == \ AlertDescription.close_notify: self._shutdown(True) elif alert.level == AlertLevel.warning: self._shutdown(False) else: #Fatal alert: self._shutdown(False) #Raise the alert as an exception raise TLSRemoteAlert(alert) #If we received a renegotiation attempt... if recordHeader.type == ContentType.handshake: subType = p.get(1) reneg = False if self._client: if subType == HandshakeType.hello_request: reneg = True else: if subType == HandshakeType.client_hello: reneg = True #Send no_renegotiation, then try again if reneg: alertMsg = Alert() alertMsg.create(AlertDescription.no_renegotiation, AlertLevel.warning) for result in self._sendMsg(alertMsg): yield result continue #Otherwise: this is an unexpected record, but neither an #alert nor renegotiation for result in self._sendError(\ AlertDescription.unexpected_message, "received type=%d" % recordHeader.type): yield result break #Parse based on content_type if recordHeader.type == ContentType.change_cipher_spec: yield ChangeCipherSpec().parse(p) elif recordHeader.type == ContentType.alert: yield Alert().parse(p) elif recordHeader.type == ContentType.application_data: yield ApplicationData().parse(p) elif recordHeader.type == ContentType.handshake: #Convert secondaryType to tuple, if it isn't already if not isinstance(secondaryType, tuple): secondaryType = (secondaryType,) #If it's a handshake message, check handshake header if recordHeader.ssl2: subType = p.get(1) if subType != HandshakeType.client_hello: for result in self._sendError(\ AlertDescription.unexpected_message, "Can only handle SSLv2 ClientHello messages"): yield result if HandshakeType.client_hello not in secondaryType: for result in self._sendError(\ AlertDescription.unexpected_message): yield result subType = HandshakeType.client_hello else: subType = p.get(1) if subType not in secondaryType: for result in self._sendError(\ AlertDescription.unexpected_message, "Expecting %s, got %s" % (str(secondaryType), subType)): yield result #Update handshake hashes sToHash = bytesToString(p.bytes) self._handshake_md5.update(sToHash) self._handshake_sha.update(sToHash) #Parse based on handshake type if subType == HandshakeType.client_hello: yield ClientHello(recordHeader.ssl2).parse(p) elif subType == HandshakeType.server_hello: yield ServerHello().parse(p) elif subType == HandshakeType.certificate: yield Certificate(constructorType).parse(p) elif subType == HandshakeType.certificate_request: yield CertificateRequest().parse(p) elif subType == HandshakeType.certificate_verify: yield CertificateVerify().parse(p) elif subType == HandshakeType.server_key_exchange: yield ServerKeyExchange(constructorType).parse(p) elif subType == HandshakeType.server_hello_done: yield ServerHelloDone().parse(p) elif subType == HandshakeType.client_key_exchange: yield ClientKeyExchange(constructorType, \ self.version).parse(p) elif subType == HandshakeType.finished: yield Finished(self.version).parse(p) else: raise AssertionError() #If an exception was raised by a Parser or Message instance: except SyntaxError, e: for result in self._sendError(AlertDescription.decode_error, formatExceptionTrace(e)): yield result #Returns next record or next handshake message def _getNextRecord(self): #If there's a handshake message waiting, return it if self._handshakeBuffer: recordHeader, bytes = self._handshakeBuffer[0] self._handshakeBuffer = self._handshakeBuffer[1:] yield (recordHeader, Parser(bytes)) return #Otherwise... #Read the next record header bytes = createByteArraySequence([]) recordHeaderLength = 1 ssl2 = False while 1: try: s = self.sock.recv(recordHeaderLength-len(bytes)) except socket.error, why: if why[0] == errno.EWOULDBLOCK: yield 0 continue else: raise #If the connection was abruptly closed, raise an error if len(s)==0: raise TLSAbruptCloseError() bytes += stringToBytes(s) if len(bytes)==1: if bytes[0] in ContentType.all: ssl2 = False recordHeaderLength = 5 elif bytes[0] == 128: ssl2 = True recordHeaderLength = 2 else: raise SyntaxError() if len(bytes) == recordHeaderLength: break #Parse the record header if ssl2: r = RecordHeader2().parse(Parser(bytes)) else: r = RecordHeader3().parse(Parser(bytes)) #Check the record header fields if r.length > 18432: for result in self._sendError(AlertDescription.record_overflow): yield result #Read the record contents bytes = createByteArraySequence([]) while 1: try: s = self.sock.recv(r.length - len(bytes)) except socket.error, why: if why[0] == errno.EWOULDBLOCK: yield 0 continue else: raise #If the connection is closed, raise a socket error if len(s)==0: raise TLSAbruptCloseError() bytes += stringToBytes(s) if len(bytes) == r.length: break #Check the record header fields (2) #We do this after reading the contents from the socket, so that #if there's an error, we at least don't leave extra bytes in the #socket.. # # THIS CHECK HAS NO SECURITY RELEVANCE (?), BUT COULD HURT INTEROP. # SO WE LEAVE IT OUT FOR NOW. # #if self._versionCheck and r.version != self.version: # for result in self._sendError(AlertDescription.protocol_version, # "Version in header field: %s, should be %s" % (str(r.version), # str(self.version))): # yield result #Decrypt the record for result in self._decryptRecord(r.type, bytes): if result in (0,1): yield result else: break bytes = result p = Parser(bytes) #If it doesn't contain handshake messages, we can just return it if r.type != ContentType.handshake: yield (r, p) #If it's an SSLv2 ClientHello, we can return it as well elif r.ssl2: yield (r, p) else: #Otherwise, we loop through and add the handshake messages to the #handshake buffer while 1: if p.index == len(bytes): #If we're at the end if not self._handshakeBuffer: for result in self._sendError(\ AlertDescription.decode_error, \ "Received empty handshake record"): yield result break #There needs to be at least 4 bytes to get a header if p.index+4 > len(bytes): for result in self._sendError(\ AlertDescription.decode_error, "A record has a partial handshake message (1)"): yield result p.get(1) # skip handshake type msgLength = p.get(3) if p.index+msgLength > len(bytes): for result in self._sendError(\ AlertDescription.decode_error, "A record has a partial handshake message (2)"): yield result handshakePair = (r, bytes[p.index-4 : p.index+msgLength]) self._handshakeBuffer.append(handshakePair) p.index += msgLength #We've moved at least one handshake message into the #handshakeBuffer, return the first one recordHeader, bytes = self._handshakeBuffer[0] self._handshakeBuffer = self._handshakeBuffer[1:] yield (recordHeader, Parser(bytes)) def _decryptRecord(self, recordType, bytes): if self._readState.encContext: #Decrypt if it's a block cipher if self._readState.encContext.isBlockCipher: blockLength = self._readState.encContext.block_size if len(bytes) % blockLength != 0: for result in self._sendError(\ AlertDescription.decryption_failed, "Encrypted data not a multiple of blocksize"): yield result ciphertext = bytesToString(bytes) plaintext = self._readState.encContext.decrypt(ciphertext) if self.version == (3,2): #For TLS 1.1, remove explicit IV plaintext = plaintext[self._readState.encContext.block_size : ] bytes = stringToBytes(plaintext) #Check padding paddingGood = True paddingLength = bytes[-1] if (paddingLength+1) > len(bytes): paddingGood=False totalPaddingLength = 0 else: if self.version == (3,0): totalPaddingLength = paddingLength+1 elif self.version in ((3,1), (3,2)): totalPaddingLength = paddingLength+1 paddingBytes = bytes[-totalPaddingLength:-1] for byte in paddingBytes: if byte != paddingLength: paddingGood = False totalPaddingLength = 0 else: raise AssertionError() #Decrypt if it's a stream cipher else: paddingGood = True ciphertext = bytesToString(bytes) plaintext = self._readState.encContext.decrypt(ciphertext) bytes = stringToBytes(plaintext) totalPaddingLength = 0 #Check MAC macGood = True macLength = self._readState.macContext.digest_size endLength = macLength + totalPaddingLength if endLength > len(bytes): macGood = False else: #Read MAC startIndex = len(bytes) - endLength endIndex = startIndex + macLength checkBytes = bytes[startIndex : endIndex] #Calculate MAC seqnumStr = self._readState.getSeqNumStr() bytes = bytes[:-endLength] bytesStr = bytesToString(bytes) mac = self._readState.macContext.copy() mac.update(seqnumStr) mac.update(chr(recordType)) if self.version == (3,0): mac.update( chr( int(len(bytes)/256) ) ) mac.update( chr( int(len(bytes)%256) ) ) elif self.version in ((3,1), (3,2)): mac.update(chr(self.version[0])) mac.update(chr(self.version[1])) mac.update( chr( int(len(bytes)/256) ) ) mac.update( chr( int(len(bytes)%256) ) ) else: raise AssertionError() mac.update(bytesStr) macString = mac.digest() macBytes = stringToBytes(macString) #Compare MACs if macBytes != checkBytes: macGood = False if not (paddingGood and macGood): for result in self._sendError(AlertDescription.bad_record_mac, "MAC failure (or padding failure)"): yield result yield bytes def _handshakeStart(self, client): self._client = client self._handshake_md5 = md5.md5() self._handshake_sha = sha.sha() self._handshakeBuffer = [] self.allegedSharedKeyUsername = None self.allegedSrpUsername = None self._refCount = 1 def _handshakeDone(self, resumed): self.resumed = resumed self.closed = False def _calcPendingStates(self, clientRandom, serverRandom, implementations): if self.session.cipherSuite in CipherSuite.aes128Suites: macLength = 20 keyLength = 16 ivLength = 16 createCipherFunc = createAES elif self.session.cipherSuite in CipherSuite.aes256Suites: macLength = 20 keyLength = 32 ivLength = 16 createCipherFunc = createAES elif self.session.cipherSuite in CipherSuite.rc4Suites: macLength = 20 keyLength = 16 ivLength = 0 createCipherFunc = createRC4 elif self.session.cipherSuite in CipherSuite.tripleDESSuites: macLength = 20 keyLength = 24 ivLength = 8 createCipherFunc = createTripleDES else: raise AssertionError() if self.version == (3,0): createMACFunc = MAC_SSL elif self.version in ((3,1), (3,2)): createMACFunc = hmac.HMAC outputLength = (macLength*2) + (keyLength*2) + (ivLength*2) #Calculate Keying Material from Master Secret if self.version == (3,0): keyBlock = PRF_SSL(self.session.masterSecret, concatArrays(serverRandom, clientRandom), outputLength) elif self.version in ((3,1), (3,2)): keyBlock = PRF(self.session.masterSecret, "key expansion", concatArrays(serverRandom,clientRandom), outputLength) else: raise AssertionError() #Slice up Keying Material clientPendingState = _ConnectionState() serverPendingState = _ConnectionState() p = Parser(keyBlock) clientMACBlock = bytesToString(p.getFixBytes(macLength)) serverMACBlock = bytesToString(p.getFixBytes(macLength)) clientKeyBlock = bytesToString(p.getFixBytes(keyLength)) serverKeyBlock = bytesToString(p.getFixBytes(keyLength)) clientIVBlock = bytesToString(p.getFixBytes(ivLength)) serverIVBlock = bytesToString(p.getFixBytes(ivLength)) clientPendingState.macContext = createMACFunc(clientMACBlock, digestmod=sha) serverPendingState.macContext = createMACFunc(serverMACBlock, digestmod=sha) clientPendingState.encContext = createCipherFunc(clientKeyBlock, clientIVBlock, implementations) serverPendingState.encContext = createCipherFunc(serverKeyBlock, serverIVBlock, implementations) #Assign new connection states to pending states if self._client: self._pendingWriteState = clientPendingState self._pendingReadState = serverPendingState else: self._pendingWriteState = serverPendingState self._pendingReadState = clientPendingState if self.version == (3,2) and ivLength: #Choose fixedIVBlock for TLS 1.1 (this is encrypted with the CBC #residue to create the IV for each sent block) self.fixedIVBlock = getRandomBytes(ivLength) def _changeWriteState(self): self._writeState = self._pendingWriteState self._pendingWriteState = _ConnectionState() def _changeReadState(self): self._readState = self._pendingReadState self._pendingReadState = _ConnectionState() def _sendFinished(self): #Send ChangeCipherSpec for result in self._sendMsg(ChangeCipherSpec()): yield result #Switch to pending write state self._changeWriteState() #Calculate verification data verifyData = self._calcFinished(True) if self.fault == Fault.badFinished: verifyData[0] = (verifyData[0]+1)%256 #Send Finished message under new state finished = Finished(self.version).create(verifyData) for result in self._sendMsg(finished): yield result def _getFinished(self): #Get and check ChangeCipherSpec for result in self._getMsg(ContentType.change_cipher_spec): if result in (0,1): yield result changeCipherSpec = result if changeCipherSpec.type != 1: for result in self._sendError(AlertDescription.illegal_parameter, "ChangeCipherSpec type incorrect"): yield result #Switch to pending read state self._changeReadState() #Calculate verification data verifyData = self._calcFinished(False) #Get and check Finished message under new state for result in self._getMsg(ContentType.handshake, HandshakeType.finished): if result in (0,1): yield result finished = result if finished.verify_data != verifyData: for result in self._sendError(AlertDescription.decrypt_error, "Finished message is incorrect"): yield result def _calcFinished(self, send=True): if self.version == (3,0): if (self._client and send) or (not self._client and not send): senderStr = "\x43\x4C\x4E\x54" else: senderStr = "\x53\x52\x56\x52" verifyData = self._calcSSLHandshakeHash(self.session.masterSecret, senderStr) return verifyData elif self.version in ((3,1), (3,2)): if (self._client and send) or (not self._client and not send): label = "client finished" else: label = "server finished" handshakeHashes = stringToBytes(self._handshake_md5.digest() + \ self._handshake_sha.digest()) verifyData = PRF(self.session.masterSecret, label, handshakeHashes, 12) return verifyData else: raise AssertionError() #Used for Finished messages and CertificateVerify messages in SSL v3 def _calcSSLHandshakeHash(self, masterSecret, label): masterSecretStr = bytesToString(masterSecret) imac_md5 = self._handshake_md5.copy() imac_sha = self._handshake_sha.copy() imac_md5.update(label + masterSecretStr + '\x36'*48) imac_sha.update(label + masterSecretStr + '\x36'*40) md5Str = md5.md5(masterSecretStr + ('\x5c'*48) + \ imac_md5.digest()).digest() shaStr = sha.sha(masterSecretStr + ('\x5c'*40) + \ imac_sha.digest()).digest() return stringToBytes(md5Str + shaStr)