WebUSB Support

Cargo.toml

@@ -16,11 +16,18 @@ default-adapters = ["panda", "socketcan"]
 all-adapters = ["default-adapters", "vector-xl", "j2534", "peak"]
 serde = ["dep:serde"]
 
+# USB backends (transports). These are orthogonal to the adapters below: an adapter that
+# speaks USB picks `RusbBackend` on native and `WebUsbBackend` on wasm via the target.
+rusb-backend = ["dep:rusb"]
+webusb = ["dep:web-sys", "dep:js-sys", "dep:console_error_panic_hook"]
+
 # adapters
 vector-xl = ["dep:bindgen", "dep:libloading"]
 j2534 = ["dep:libloading", "dep:winreg"]
-panda = ["dep:rusb"]
-peak = ["dep:rusb"]
+# `panda`/`peak` default to the rusb backend so `--features panda` is a working native
+# build. For the browser, add the WebUSB transport: `--features panda,webusb`.
+panda = ["rusb-backend"]
+peak = ["rusb-backend"]
 socketcan = ["dep:libc", "dep:socket2"]
 
 # adapter tests
@@ -35,14 +42,44 @@ test-vector = ["vector-xl"]
 async-stream = "0.3.5"
 bstr = "1.9.0"
 hex = "0.4"
-rusb = { version = "0.9", optional = true }
 serde = { version = "1.0.197", features = ["derive"], optional = true }
 strum = "0.26"
 strum_macros = "0.26"
 thiserror = "1.0.58"
+# Base (wasm-compatible) tokio. Native re-declares tokio with the "full" feature below.
+tokio = { version = "1.36.0", default-features = false, features = ["sync"] }
+tokio-stream = { version = "0.1.14", default-features = false }
+tracing = "0.1"
+
+# WebUSB backend dependencies (only built with the `webusb` feature, on wasm targets).
+web-sys = { version = "0.3", optional = true, features = [
+    "Window",
+    "Navigator",
+    "Usb",
+    "UsbDevice",
+    "UsbDeviceRequestOptions",
+    "UsbControlTransferParameters",
+    "UsbRequestType",
+    "UsbRecipient",
+    "UsbInTransferResult",
+    "UsbOutTransferResult",
+] }
+js-sys = { version = "0.3", optional = true }
+console_error_panic_hook = { version = "0.1", optional = true }
+
+# Native-only: rusb (libusb won't cross-compile to wasm, so it lives here and the
+# `rusb-backend`/`panda` features only pull it on native), a minimal block_on (used by
+# AsyncCanAdapter's processing thread), and the full tokio runtime/stream features.
+[target.'cfg(not(target_arch = "wasm32"))'.dependencies]
+rusb = { version = "0.9", optional = true }
+pollster = "0.3"
 tokio = { version = "1.36.0", features = ["full"] }
 tokio-stream = "0.1.14"
-tracing = "0.1"
+
+# Browser-only: wasm-bindgen glue used to drive the adapter via spawn_local.
+[target.'cfg(target_arch = "wasm32")'.dependencies]
+wasm-bindgen = "0.2"
+wasm-bindgen-futures = "0.4"
 
 [target.'cfg(target_os = "linux")'.dependencies]
 socket2 = { version = "0.6.0", optional = true }

scripts/release_peak_usb.sh

@@ -0,0 +1,27 @@
+#!/usr/bin/env bash
+# Release PEAK PCAN-USB FD adapters from the in-kernel `peak_usb` driver so a browser
+# (WebUSB) or raw libusb can claim them.
+#
+# Re-bind later by replugging the device, or:
+#   sudo modprobe -r peak_usb && sudo modprobe peak_usb
+set -euo pipefail
+
+DRIVER=/sys/bus/usb/drivers/peak_usb
+
+if [ ! -d "$DRIVER" ]; then
+    echo "peak_usb driver not loaded; nothing bound."
+    exit 0
+fi
+
+found=0
+for iface in "$DRIVER"/*:*; do
+    [ -e "$iface" ] || continue
+    name=$(basename "$iface")
+    echo "Unbinding $name from peak_usb"
+    echo -n "$name" | sudo tee "$DRIVER/unbind" > /dev/null
+    found=1
+done
+
+if [ "$found" -eq 0 ]; then
+    echo "No PEAK devices currently bound to peak_usb."
+fi

src/can/adapter.rs

@@ -5,7 +5,7 @@
 /// Adapter backends are feature-gated. If no adapter features are enabled, or no
 /// supported hardware/interface is available, this returns [`crate::error::Error::NotFound`].
 pub fn get_adapter() -> Result<crate::can::AsyncCanAdapter, crate::error::Error> {
-    #[cfg(feature = "panda")]
+    #[cfg(all(not(target_arch = "wasm32"), feature = "panda"))]
     {
         let bitrate_cfg = crate::can::bitrate::BitrateBuilder::new::<crate::panda::Panda>()
             .bitrate(500_000)
@@ -20,7 +20,7 @@ pub fn get_adapter() -> Result<crate::can::AsyncCanAdapter, crate::error::Error>
         }
     }
 
-    #[cfg(feature = "peak")]
+    #[cfg(all(not(target_arch = "wasm32"), feature = "peak"))]
     {
         let bitrate_cfg = crate::can::bitrate::BitrateBuilder::new::<crate::peak::Peak>()
             .bitrate(500_000)