https://en.wikipedia.org/wiki/Man-in-the-middle_attack

firmware/config/engines/bmw_n73.cpp

@@ -87,7 +87,7 @@ TCU_SERVICE = 0x598
 TCU_INPA_RESPONSE = 0x6f1
 
 ECU_BUS = 1
-GEAR_BUS = 2
+TCU_BUS = 2
 
 canRxAdd(E90_TORQUE_1)
 canRxAdd(E90_TORQUE_2)
@@ -116,7 +116,7 @@ canRxAdd(TCU_INPA_RESPONSE)
 
 
 function relayToTcu(id, data)
-	txCan(GEAR_BUS, id, 0, data) -- relay non-TCU message to TCU
+	txCan(TCU_BUS, id, 0, data) -- relay non-TCU message to TCU
 end
 
 function relayToEcu(id, data)
@@ -129,7 +129,7 @@ end
 
 hexstr = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, "A", "B", "C", "D", "E", "F" }
 
-function decimalToHex(num)
+function toHexString(num)
 	if num == 0 then
 		return '0'
 	end
@@ -143,11 +143,11 @@ function decimalToHex(num)
 	return result
 end
 
-function print_array(arr)
+function arrayToString(arr)
 	local str = ""
 	local index = 1
 	while arr[index] ~= nil do
-		str = str.." "..decimalToHex(arr[index])
+		str = str.." "..toHexString(arr[index])
 		index = index + 1
 	end
 	return str
@@ -174,8 +174,8 @@ function onCanRx(bus, id, dlc, data)
         output[2] = counterE90_RPM_THROTTLE
         output[1] = bmwChecksum(E90_RPM_THROTTLE, output, 2, 7)
 
---		print('original ' ..print_array(data))
+--		print('original ' ..arrayToString(data))
---		print('repacked ' ..print_array(output))
+--		print('repacked ' ..arrayToString(output))
 
 		relayToTcu(id, output)
 	elseif id == E90_DSC_TORQUE_DEMAND then
@@ -266,6 +266,7 @@ function onCanRx(bus, id, dlc, data)
 end
 
 function onTick()
+ -- empty 'onTick' until we make 'onTick' method optional
 end
 
 )", efi::size(config->luaScript));

firmware/controllers/lua/examples/man-in-the-middle.txt

@@ -0,0 +1,42 @@
+-- sometimes we want to cut a CAN bus and install rusEFI into that cut
+-- https://en.wikipedia.org/wiki/Man-in-the-middle_attack
+
+
+-- this controls onCanRx rate as well!
+setTickRate(300)
+
+
+ECU_BUS = 1
+-- really 'not ECU'
+TCU_BUS = 2
+
+hexstr = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, "A", "B", "C", "D", "E", "F" }
+
+function toHexString(num)
+	if num == 0 then
+		return '0'
+	end
+
+	local result = ""
+	while num > 0 do
+		local n = num % 16
+		result = hexstr[n + 1] ..result
+		num = math.floor(num / 16)
+	end
+	return result
+end
+
+function arrayToString(arr)
+	local str = ""
+	local index = 1
+	while arr[index] ~= nil do
+		str = str.." "..toHexString(arr[index])
+		index = index + 1
+	end
+	return str
+end
+
+
+function onTick()
+ -- empty 'onTick' until we make 'onTick' method optional
+end