# This is a combination of 2 commits.

# This is the 1st commit message:

simulator: implement a simulator for bitbox02 device

HWI is thinking of updating its support policy such that supported wallets
must implement a simulator/emulator. See bitcoin-core/HWI#685.
That's why a simulator is implemented for bitbox02, supporting functionalities of
its API.

This first version of the simulator is capable of nearly every functionality of a
normal Bitbox02 device, without promising any security or production use. Its main
aim is to be able to run unit tests for features and test the API.

In addition, it will be configured to run automated tests in CI, which helps both
us and HWI integration.

Right now, the simulator has 3 different ways to communicate with a client: giving
inputs/getting output from CLI, using pipes or opening sockets. Socket is the most
convenient and reliable choice in this version. It expects the clients to open a
socket on port 15432, which is selected intentionally to avoid possible conflicts.

The simulator resides with C unit-tests since it uses same mocks, therefore it can
be built by `make unit-test`.

Lastly, Python client implemented in `py/send_message.py` is updated to support
communicating with simulator with the socket configuration mentioned above. Client
can be started up with `./py/send_message.py --simulator` command. To run the
simulator, `build-build/bin/test_simulator` command is sufficient.

Signed-off-by: asi345 <[email protected]>

# This is the commit message BitBoxSwiss#2:

demo code how plug simulate a bitbox02 in the Py client library

.vscode/settings.json

@@ -0,0 +1,6 @@
+{
+    "files.associations": {
+        "string.h": "c",
+        "queue.h": "c"
+    }
+}

py/send_message.py

@@ -41,6 +41,7 @@
     FirmwareVersionOutdatedException,
     u2fhid,
     bitbox_api_protocol,
+    PhysicalLayer,
 )
 
 import u2f
@@ -1555,6 +1556,31 @@ def run(self) -> int:
         self._device.close()
         return 0
 
+def connect_to_simulator_bitbox(debug: bool) -> int:
+    class Simulator(PhysicalLayer):
+        def write(self, data: bytes) -> None:
+            raise Exception(f"TODO: write {data.hex()} to simulator")
+
+        def read(self, size: int, timeout_ms: int) -> bytes:
+            raise Exception(f"TODO: read {size} bytes from simulator")
+
+    simulator = Simulator()
+
+    device_info = {
+        "serial_number": "v9.15.0",
+        "path": "",
+        "product_string": "BitBox02BTC",
+    }
+    noise_config = bitbox_api_protocol.BitBoxNoiseConfig()
+    bitbox_connection = bitbox02.BitBox02(
+        transport=u2fhid.U2FHid(simulator), device_info=device_info, noise_config=noise_config,
+    )
+    try:
+        bitbox_connection.check_min_version()
+    except FirmwareVersionOutdatedException as exc:
+        print("WARNING: ", exc)
+
+    return SendMessage(bitbox_connection, debug).run()
 
 def connect_to_usb_bitbox(debug: bool, use_cache: bool) -> int:
     """
@@ -1643,6 +1669,7 @@ def main() -> int:
     parser = argparse.ArgumentParser(description="Tool for communicating with bitbox device")
     parser.add_argument("--debug", action="store_true", help="Print messages sent and received")
     parser.add_argument("--u2f", action="store_true", help="Use u2f menu instead")
+    parser.add_argument("--simulator", action="store_true", help="Connect to the BitBox02 simulator instead of a real BitBox02")
     parser.add_argument(
         "--no-cache", action="store_true", help="Don't use cached or store noise keys"
     )
@@ -1663,6 +1690,9 @@ def main() -> int:
             return u2fapp.run()
         return 1
 
+    if args.simulator:
+        return connect_to_simulator_bitbox(args.debug)
+
     return connect_to_usb_bitbox(args.debug, not args.no_cache)
 
 

test/unit-test/simulator.c

@@ -0,0 +1,72 @@
+// Copyright 2023 Shift Cryptosecurity AG
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+
+/*
+infinite loop reading stdin line by line
+each line is e.g. a hex encoded string containing the USB message that is sent by the host (e.g. the USB msgs that is sent by the bitbox-api-rs client library)
+process the usb message
+print the response usb messages to stdout, again one message per line, hex encoded
+
+somehow expose a usb connection to this c program. There read the messages from stdin and write the responses to stdout.
+When read the message, call the message handling function of the firmware so that it takes care of everything and returns the output
+*/
+
+#include <stdio.h>
+#include "../../src/usb/usb_processing.h"
+
+#define USB_DESC_HID_EP_SIZE 0x40
+#define USB_REPORT_SIZE USB_DESC_HID_EP_SIZE
+#define USB_HID_REPORT_IN_SIZE USB_REPORT_SIZE
+#define USB_HID_REPORT_OUT_SIZE USB_REPORT_SIZE
+
+char* get_usb_message(char* input) {
+    char* res = fgets(input, sizeof(input), stdin);
+    input[strcspn(input, "\n\r")] = 0;
+    return res;
+}
+
+void simulate_firmware_execution(char* input) {
+    //u2f_packet_process
+
+    //usb_processing_process
+    //chain of call: firmware_main_loop -> usb_processing_process -> _usb_consume_incoming_packets ->
+    // _usb_execute_packet
+    //usb_processing_process(usb_processing_hww());
+    /* First, process all the incoming USB traffic. */
+    //usb_processing_process(usb_processing_hww());
+    /*
+    * If USB has generated events at the application level,
+    * process them now.
+    */
+    //hww_process();
+
+    //usb_packet_process but it puts the packet into queue
+    //chain of call: usb_packet_process -> usb_processing_enqueue -> _build_packet
+    static uint8_t _out_report[USB_HID_REPORT_OUT_SIZE];
+    memccpy(_out_report, input, 0, sizeof(_out_report));
+    usb_packet_process((const USB_FRAME*)_out_report);
+}
+
+int main(void) {
+    char buffer[4096];
+    while (get_usb_message(buffer)) {
+        if (strcmp(buffer, "") == 0) {
+            break;
+        }
+        printf("received: %s\n", buffer);
+        simulate_firmware_execution(buffer);
+    }
+    return 0;
+}