void safety_rx_hook(CAN_FIFOMailBox_TypeDef *to_push) {
  // state machine to enter and exit controls
  // 0x1A6 for the ILX, 0x296 for the Civic Touring
  if ((to_push->RIR>>21) == 0x1A6 || (to_push->RIR>>21) == 0x296) {
    int buttons = (to_push->RDLR & 0xE0) >> 5;
    if (buttons == 4 || buttons == 3) {
      controls_allowed = 1;
    } else if (buttons == 2) {
      controls_allowed = 0;
    }
  }

  // exit controls on brake press
  if ((to_push->RIR>>21) == 0x17C) {
    // bit 50
    if (to_push->RDHR & 0x200000) {
      controls_allowed = 0;
    }
  }

  // exit controls on gas press if interceptor
  if ((to_push->RIR>>21) == 0x201) {
    gas_interceptor_detected = 1;
    int gas = ((to_push->RDLR & 0xFF) << 8) | ((to_push->RDLR & 0xFF00) >> 8);
    if (gas > 328) {
      controls_allowed = 0;
    }
  }

  // exit controls on gas press if no interceptor
  if (!gas_interceptor_detected) {
    if ((to_push->RIR>>21) == 0x17C) {
      if (to_push->RDLR & 0xFF) {
        controls_allowed = 0;
      }
    }
  }
}

void safety_tx_hook(CAN_FIFOMailBox_TypeDef *to_send) {
  // BRAKE: safety check
  if ((to_send->RIR>>21) == 0x1FA) {
    if (controls_allowed) {
      to_send->RDLR &= 0xFFFFFF3F;
    } else {
      to_send->RDLR &= 0xFFFF0000;
    }
  }

  // STEER: safety check
  if ((to_send->RIR>>21) == 0xE4) {
    if (controls_allowed) {
      to_send->RDLR &= 0xFFFFFFFF;
    } else {
      to_send->RDLR &= 0xFFFF0000;
    }
  } 

  // GAS: safety check
  if ((to_send->RIR>>21) == 0x200) {
    if (controls_allowed) {
      to_send->RDLR &= 0xFFFFFFFF;
    } else {
      to_send->RDLR &= 0xFFFF0000;
    }
  } 

  // block all other messages?
}