ELM327: Panda safety mode for ELM327 (passes ISO 15765-4 11&29 bit messages)

board/main.c

@@ -251,7 +251,8 @@ int usb_cb_control_msg(USB_Setup_TypeDef *setup, uint8_t *resp, int hardwired) {
     case 0xdc:
       // this is the only way to leave silent mode
       // and it's blocked over WiFi
-      if (hardwired) {
+      // Allow ELM security mode to be set over wifi.
+      if (hardwired || setup->b.wValue.w == SAFETY_ELM327) {
         safety_set_mode(setup->b.wValue.w);
         can_silent = (setup->b.wValue.w == SAFETY_NOOUTPUT);
         can_init_all();
@@ -508,4 +509,3 @@ int main() {
 
   return 0;
 }
-

board/safety.h

@@ -20,6 +20,7 @@ int controls_allowed = 0;
 // Include the actual safety policies.
 #include "safety/safety_defaults.h"
 #include "safety/safety_honda.h"
+#include "safety/safety_elm327.h"
 
 const safety_hooks *current_hooks = &nooutput_hooks;
 
@@ -43,11 +44,13 @@ typedef struct {
 #define SAFETY_NOOUTPUT 0
 #define SAFETY_HONDA 1
 #define SAFETY_ALLOUTPUT 0x1337
+#define SAFETY_ELM327 0xE327
 
 const safety_hook_config safety_hook_registry[] = {
   {SAFETY_NOOUTPUT, &nooutput_hooks},
   {SAFETY_HONDA, &honda_hooks},
   {SAFETY_ALLOUTPUT, &alloutput_hooks},
+  {SAFETY_ELM327, &elm327_hooks},
 };
 
 #define HOOK_CONFIG_COUNT (sizeof(safety_hook_registry)/sizeof(safety_hook_config))
@@ -56,10 +59,9 @@ int safety_set_mode(uint16_t mode){
   for (int i = 0; i < HOOK_CONFIG_COUNT; i++) {
     if (safety_hook_registry[i].id == mode) {
       current_hooks = safety_hook_registry[i].hooks;
-      current_hooks->init();
+      if(current_hooks->init) current_hooks->init();
       return 0;
     }
   }
   return -1;
 }
-

board/safety/safety_elm327.h

@@ -0,0 +1,31 @@
+static void elm327_rx_hook(CAN_FIFOMailBox_TypeDef *to_push) {}
+
+static int elm327_tx_hook(CAN_FIFOMailBox_TypeDef *to_send) {
+  //All ELM traffic must appear on CAN0
+  if(((to_send->RDTR >> 4) & 0xf) != 0) return 0;
+  //All ISO 15765-4 messages must be 8 bytes long
+  if((to_send->RDTR & 0xf) != 8) return 0;
+
+  if(to_send->RIR & 4){
+    uint32_t addr = to_send->RIR >> 3;
+    //Check valid 29 bit send addresses for ISO 15765-4
+    if(!(addr == 0x18DB33F1 || (addr & 0x1FFF00FF) == 0x18DA00F1)) return 0;
+  } else {
+    uint32_t addr = to_send->RIR >> 21;
+    //Check valid 11 bit send addresses for ISO 15765-4
+    if(!(addr == 0x7DF || (addr & 0x7F8) == 0x7E0)) return 0;
+  }
+
+  return true;
+}
+
+//static int elm327_tx_lin_hook(int lin_num, uint8_t *data, int len) {
+//  return false;
+//}
+
+const safety_hooks elm327_hooks = {
+  .init = NULL,
+  .rx = elm327_rx_hook,
+  .tx = elm327_tx_hook,
+  .tx_lin = nooutput_tx_lin_hook,
+};

boardesp/elm327.c

@@ -828,7 +828,7 @@ static void ICACHE_FLASH_ATTR elm_process_at_cmd(char *cmd, uint16_t len) {
 
     elm_append_rsp_const("\r\r");
     elm_append_rsp_const(IDENT_MSG);
-    panda_set_safety_mode(0x1337);
+    panda_set_safety_mode(0xE327);
     elm_switch_proto();
     return;
   default:

tests/automated/elm_wifi.py

@@ -8,6 +8,8 @@ import pytest
 
 sys.path.append(os.path.join(os.path.dirname(os.path.realpath(__file__)), ".."))
 import elm_car_simulator
+sys.path.append(os.path.join(os.path.dirname(os.path.realpath(__file__)), "..", ".."))
+from panda import Panda
 
 def elm_connect():
     s = socket.create_connection(("192.168.0.10", 35000))
@@ -405,3 +407,54 @@ def test_elm_can_baud():
         sim.stop()
         sim.join()
         s.close()
+
+def test_elm_panda_safety_mode_ISO15765():
+    s = elm_connect()
+    serial = os.getenv("CANSIMSERIAL") if os.getenv("CANSIMSERIAL") else None
+    p_car = Panda(serial) # Configure this so the messages will send
+    p_car.set_can_speed_kbps(0, 500)
+    p_car.set_safety_mode(Panda.SAFETY_ALLOUTPUT)
+
+    p_elm = Panda("WIFI")
+
+    #sim = elm_car_simulator.ELMCanCarSimulator(serial)
+    #sim.start()
+
+    def did_send(p, addr, dat, bus):
+        p.can_send(addr, dat, bus)
+        t = time.time()
+        while time.time()-t < 0.5:
+            msg = p.can_recv()
+            for addrin, _, datin, busin in msg:
+                if (0x80 | bus) == busin and addr == addrin and datin == dat:
+                    return True
+            time.sleep(0.01)
+        return False
+
+    try:
+        sync_reset(s) # Reset elm (which requests the ELM327 safety mode)
+        send_compare(s, b'ATSP6\r', b"ATSP6\rOK\r\r>") # Set Proto ISO 15765-4 (CAN 11/500)
+
+        #29 bit
+        assert not did_send(p_elm, 0x18DB33F1, b'\x02\x01\x00\x00\x00\x00\x00\x00', 1) #wrong canid
+        assert not did_send(p_elm, 0x18DB33F1, b'\x02\x01\x00', 0) #wrong length
+        assert not did_send(p_elm, 0x10000000, b'\x02\x01\x00\x00\x00\x00\x00\x00', 0) #bad addr
+        assert not did_send(p_elm, 0x18DAF133, b'\x02\x01\x00\x00\x00\x00\x00\x00', 0) #bad addr (phy addr)
+        assert not did_send(p_elm, 0x18DAF000, b'\x02\x01\x00\x00\x00\x00\x00\x00', 0) #bad addr
+        assert not did_send(p_elm, 0x18DAF1F3, b'\x02\x01\x00\x00\x00\x00\x00\x00', 0) #bad addr! (phys rsp to elm)
+
+        assert did_send(p_elm, 0x18DB33F1, b'\x02\x01\x00\x00\x00\x00\x00\x00', 0) #good! (obd func req)
+        assert did_send(p_elm, 0x18DA10F1, b'\x02\x01\x00\x00\x00\x00\x00\x00', 0) #good! (phys response)
+
+        #11 bit
+        assert not did_send(p_elm, 0X7DF, b'\x02\x01\x00\x00\x00\x00\x00\x00', 1) #wrong canid
+        assert not did_send(p_elm, 0X7DF, b'\x02\x01\x00', 0) #wrong length
+        assert not did_send(p_elm, 0xAA, b'\x02\x01\x00\x00\x00\x00\x00\x00', 0) #bad addr
+        assert not did_send(p_elm, 0x7DA, b'\x02\x01\x00\x00\x00\x00\x00\x00', 0) #bad addr (phy addr)
+        assert not did_send(p_elm, 0x7E8, b'\x02\x01\x00\x00\x00\x00\x00\x00', 0) #bad addr (sending 'response')
+
+        assert did_send(p_elm, 0x7DF, b'\x02\x01\x00\x00\x00\x00\x00\x00', 0) #good! (obd func req)
+        assert did_send(p_elm, 0x7E1, b'\x02\x01\x00\x00\x00\x00\x00\x00', 0) #good! (phys response)
+
+    finally:
+        s.close()