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194 lines
11 KiB
Python
194 lines
11 KiB
Python
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# This module handles the IPv6 related functionality of the communication between charging station and car.
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#
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# It has the following sub-functionalities:
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# - IP.UDP.SDP: listen to requests from the car, and responding to them.
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# Eth --> IPv6 --> UDP --> V2GTP --> SDP
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# |
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# v
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# Eth <-- IPv6 <-- UDP <-- V2GTP <-- SDP
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#
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#
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# Abbreviations:
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# SECC: Supply Equipment Communication Controller. The "computer" of the charging station.
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# EVCC: Electric Vehicle Communication Controller. The "computer" of the vehicle.
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# SDP: SECC Discovery Protocol. The UDP based protocol to find out the IP address of the charging station.
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# SLAAC: Stateless auto address configuration (not SLAC!). A method to automatically set IPv6 address, based
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# on the 6 byte MAC address.
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from helpers import showAsHex
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import udpChecksum
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class ipv6handler():
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def fillMac(self, macbytearray, position=6): # position 6 is the source MAC
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for i in range(0, 6):
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self.EthResponse[6+i] = macbytearray[i]
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def packResponseIntoEthernet(self, buffer):
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# packs the IP packet into an ethernet packet
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self.EthResponse = bytearray(len(buffer) + 6 + 6 + 2) # Ethernet header needs 14 bytes:
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# 6 bytes destination MAC
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# 6 bytes source MAC
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# 2 bytes EtherType
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for i in range(0, 6): # fill the destination MAC with the source MAC of the received package
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self.EthResponse[i] = self.myreceivebuffer[6+i]
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self.fillMac(self.ownMac) # bytes 6 to 11 are the source MAC
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self.EthResponse[12] = 0x86 # 86dd is IPv6
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self.EthResponse[13] = 0xdd
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for i in range(0, len(buffer)):
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self.EthResponse[14+i] = buffer[i]
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self.transmit(self.EthResponse)
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def packResponseIntoIp(self, buffer):
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# embeds the (SDP) response into the lower-layer-protocol: IP, Ethernet
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self.IpResponse = bytearray(len(buffer) + 8 + 16 + 16) # IP6 needs 40 bytes:
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# 4 bytes traffic class, flow
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# 2 bytes destination port
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# 2 bytes length (incl checksum)
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# 2 bytes checksum
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self.IpResponse[0] = 0x60 # traffic class, flow
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self.IpResponse[1] = 0
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self.IpResponse[2] = 0
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self.IpResponse[3] = 0
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plen = len(buffer) # length of the payload. Without headers.
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self.IpResponse[4] = plen >> 8
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self.IpResponse[5] = plen & 0xFF
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self.IpResponse[6] = 0x11 # next level protocol, 0x11 = UDP in this case
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self.IpResponse[7] = 0x0A # hop limit
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for i in range(0, 16):
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self.IpResponse[8+i] = self.SeccIp[i] # source IP address
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for i in range(0, 16):
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self.IpResponse[24+i] = self.EvccIp[i] # destination IP address
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for i in range(0, len(buffer)):
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self.IpResponse[40+i] = buffer[i]
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showAsHex(self.IpResponse, "IP response ")
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self.packResponseIntoEthernet(self.IpResponse)
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def packResponseIntoUdp(self, buffer):
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# embeds the (SDP) response into the lower-layer-protocol: UDP
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self.UdpResponse = bytearray(len(buffer) + 8) # UDP needs 8 bytes:
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# 2 bytes source port
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# 2 bytes destination port
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# 2 bytes length (incl checksum)
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# 2 bytes checksum
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self.UdpResponse[0] = 15118 >> 8
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self.UdpResponse[1] = 15118 & 0xFF
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self.UdpResponse[2] = self.evccPort >> 8
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self.UdpResponse[3] = self.evccPort & 0xFF
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lenInclChecksum = len(buffer) + 8
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self.UdpResponse[4] = lenInclChecksum >> 8
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self.UdpResponse[5] = lenInclChecksum & 0xFF
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# checksum will be calculated afterwards
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self.UdpResponse[6] = 0
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self.UdpResponse[7] = 0
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for i in range(0, len(buffer)):
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self.UdpResponse[8+i] = buffer[i]
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showAsHex(self.UdpResponse, "UDP response ")
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# The content of buffer is ready. We can calculate the checksum. see https://en.wikipedia.org/wiki/User_Datagram_Protocol
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checksum = udpChecksum.calculateUdpChecksumForIPv6(self.UdpResponse, self.SeccIp, self.EvccIp)
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self.UdpResponse[6] = checksum >> 8
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self.UdpResponse[7] = checksum & 0xFF
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self.packResponseIntoIp(self.UdpResponse)
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def sendSdpResponse(self):
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# SECC Discovery Response.
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# The response from the charger to the EV, which transfers the IPv6 address of the charger to the car.
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self.SdpPayload = bytearray(20) # SDP response has 20 bytes
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for i in range(0, 16):
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self.SdpPayload[i] = self.SeccIp[i] # 16 bytes IP address of the charger
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self.SdpPayload[16] = 15118 >> 8 # SECC port high byte. Port is always 15118.
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self.SdpPayload[17] = 15118 & 0xFF # SECC port low byte. Port is always 15118.
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self.SdpPayload[18] = 0x10 # security. We only support "no transport layer security, 0x10".
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self.SdpPayload[19] = 0x00 # transport protocol. We only support "TCP, 0x00".
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showAsHex(self.SdpPayload, "SDP payload ")
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# add the SDP header
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lenSdp = len(self.SdpPayload)
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self.V2Gframe = bytearray(lenSdp + 8) # V2GTP header needs 8 bytes:
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# 1 byte protocol version
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# 1 byte protocol version inverted
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# 2 bytes payload type
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# 4 byte payload length
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self.V2Gframe[0] = 0x01 # version
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self.V2Gframe[1] = 0xfe # version inverted
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self.V2Gframe[2] = 0x90 # payload type. 0x9001 is the SDP response message
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self.V2Gframe[3] = 0x01 #
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self.V2Gframe[4] = (lenSdp >> 24) & 0xff # length 4 byte.
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self.V2Gframe[5] = (lenSdp >> 16) & 0xff
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self.V2Gframe[6] = (lenSdp >> 8) & 0xff
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self.V2Gframe[7] = lenSdp & 0xff
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for i in range(0, lenSdp):
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self.V2Gframe[8+i] = self.SdpPayload[i]
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showAsHex(self.V2Gframe, "V2Gframe ")
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self.packResponseIntoUdp(self.V2Gframe)
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def evaluateUdpPayload(self):
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if (self.destinationport == 15118): # port for the SECC
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if ((self.udpPayload[0]==0x01) and (self.udpPayload[1]==0xFE)): # protocol version 1 and inverted
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# it is a V2GTP message
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showAsHex(self.udpPayload, "V2GTP ")
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self.evccPort = self.sourceport
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v2gptPayloadType = self.udpPayload[2] * 256 + self.udpPayload[3]
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# 0x8001 EXI encoded V2G message
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# 0x9000 SDP request message (SECC Discovery)
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# 0x9001 SDP response message (SECC response to the EVCC)
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if (v2gptPayloadType == 0x9000):
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v2gptPayloadLen = self.udpPayload[4] * 256 ** 3 + self.udpPayload[5] * 256 ** 2 + self.udpPayload[6] * 256 + self.udpPayload[7]
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if (v2gptPayloadLen == 2):
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# 2 is the only valid length for a SDP request.
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seccDiscoveryReqSecurity = self.udpPayload[8] # normally 0x10 for "no transport layer security". Or 0x00 for "TLS".
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seccDiscoveryReqTransportProtocol = self.udpPayload[9] # normally 0x00 for TCP
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if (seccDiscoveryReqSecurity!=0x10):
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print("seccDiscoveryReqSecurity " + str(seccDiscoveryReqSecurity) + " is not supported")
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else:
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if (seccDiscoveryReqTransportProtocol!=0x00):
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print("seccDiscoveryReqTransportProtocol " + str(seccDiscoveryReqTransportProtocol) + " is not supported")
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else:
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# This was a valid SDP request. Let's respond, if we are the charger.
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print("ok, this was a valid SDP request")
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if (self.iAmEvse==1):
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print("We are the SECC. Sending SDP response.")
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self.sendSdpResponse()
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else:
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print("v2gptPayloadLen on SDP request is " + str(v2gptPayloadLen) + " not supported")
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else:
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print("v2gptPayloadType " + hex(v2gptPayloadType) + " not supported")
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def enterPevMode(self):
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self.iAmEvse = 0 # not emulating a charging station
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self.iAmPev = 1 # emulating a vehicle
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def enterEvseMode(self):
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self.iAmEvse = 1 # emulating a charging station
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self.iAmPev = 0 # not emulating a vehicle
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def enterListenMode(self):
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self.iAmEvse = 0 # not emulating a charging station
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self.iAmPev = 0 # not emulating a vehicle
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def evaluateReceivedPacket(self, pkt):
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if (len(pkt)>60):
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self.myreceivebuffer = pkt
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self.nextheader = self.myreceivebuffer[20]
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if (self.nextheader == 0x11): # it is an UDP frame
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self.sourceport = self.myreceivebuffer[54] * 256 + self.myreceivebuffer[55]
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self.destinationport = self.myreceivebuffer[56] * 256 + self.myreceivebuffer[57]
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self.udplen = self.myreceivebuffer[58] * 256 + self.myreceivebuffer[59]
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self.udpsum = self.myreceivebuffer[60] * 256 + self.myreceivebuffer[61]
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# udplen is including 8 bytes header at the begin
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if (self.udplen>8):
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self.udpPayload = bytearray(self.udplen-8)
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# print("self.udplen=" + str(self.udplen))
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# print("self.myreceivebuffer len=" + str(len(self.myreceivebuffer)))
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for i in range(0, self.udplen-8):
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#print("index " + str(i) + " " + hex(self.myreceivebuffer[62+i]))
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self.udpPayload[i] = self.myreceivebuffer[62+i]
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self.evaluateUdpPayload()
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def __init__(self, transmitCallback):
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self.enterEvseMode()
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self.transmit = transmitCallback
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self.SeccIp = [ 0xfe, 0x80, 0, 0, 0, 0, 0, 0, 0x06, 0xaa, 0xaa, 0xff, 0xfe, 0, 0xaa, 0xaa ] # 16 bytes, a default IPv6 address for the charging station
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self.EvccIp = [ 0xfe, 0x80, 0, 0, 0, 0, 0, 0, 0x06, 0x65, 0x65, 0xff, 0xfe, 0, 0x64, 0xC3 ] # 16 bytes, a default IPv6 address for the vehicle
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self.ownMac = [ 0x01, 0x02, 0x03, 0x04, 0x05, 0x06 ] # 6 bytes own MAC default. Should be overwritten before use.
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