openthread-br: locate the RCP dongle through otbr-rcp

net/openthread-br/Makefile

@@ -4,13 +4,13 @@
 include $(TOPDIR)/rules.mk
 
 PKG_NAME:=openthread-br
-PKG_SOURCE_DATE:=2025-06-12
-PKG_SOURCE_VERSION:=2f3c799c7463c8f674754e65c53f78bc0bbcbd58
+PKG_VERSION:=2026.08.0
+PKG_SOURCE_VERSION:=v$(PKG_VERSION)
 PKG_RELEASE:=2
 
 PKG_SOURCE_PROTO:=git
 PKG_SOURCE_URL=https://github.com/openthread/ot-br-posix.git
-PKG_MIRROR_HASH:=fae1c7c88102f88bac32f8ee25e044b9a8781eef6b9acef39388e1e11a44a195
+PKG_MIRROR_HASH:=4645fefcf89d0c06de87bbfa9e52e2a522de48fa52146427669323c894405eb9
 
 PKG_MAINTAINER:=Stijn Tintel <stijn@linux-ipv6.be>
 PKG_LICENSE:=BSD-3-Clause
@@ -41,9 +41,7 @@ define Package/openthread-br
 	+libreadline \
 	+libstdcpp \
 	+libubox \
-	+libubus \
-	+mdnsd \
-	+mdnsresponder
+	+libubus
 endef
 
 define Package/openthread-br/description
@@ -63,15 +61,15 @@ CMAKE_OPTIONS += \
 	-DOT_TARGET_OPENWRT=ON \
 	-DOTBR_BACKBONE_ROUTER=ON \
 	-DOTBR_BORDER_ROUTING=ON \
-	-DOTBR_DNSSD_DISCOVERY_PROXY=ON \
-	-DOTBR_DUA_ROUTING=ON \
-	-DOTBR_MDNS=mDNSResponder \
+	-DOTBR_MDNS=openthread \
 	-DOTBR_NAT64=OFF \
 	-DOTBR_OPENWRT=ON \
+	-DOTBR_PRODUCT_NAME=BorderRouter \
 	-DOTBR_REST=ON \
-	-DOTBR_SRP_ADVERTISING_PROXY=ON \
 	-DOTBR_SRP_SERVER_AUTO_ENABLE=ON \
-	-DOTBR_TREL=ON
+	-DOTBR_TREL=ON \
+	-DOTBR_VENDOR_NAME=OpenThread \
+	-DOTBR_VERSION=$(PKG_VERSION)
 
 TARGET_CFLAGS += -DOPENTHREAD_POSIX_CONFIG_DAEMON_SOCKET_BASENAME=\\\"/var/run/openthread-%s\\\"
 
@@ -93,10 +91,13 @@ endef
 
 define Package/openthread-br/install
 	$(INSTALL_DIR) \
+		$(1)/etc/hotplug.d/usb \
 		$(1)/etc/init.d \
 		$(1)/lib/netifd/proto \
 		$(1)/usr/sbin
 	$(INSTALL_BIN) ./files/openthread-proto.sh $(1)/lib/netifd/proto/openthread.sh
+	$(INSTALL_BIN) ./files/otbr-rcp $(1)/usr/sbin
+	$(INSTALL_DATA) ./files/otbr-rcp.hotplug $(1)/etc/hotplug.d/usb/50-otbr-rcp
 	$(INSTALL_BIN) $(PKG_INSTALL_DIR)/usr/sbin/* $(1)/usr/sbin
 endef
 

net/openthread-br/README.md

@@ -25,6 +25,30 @@ the package will likely result in more bug reports. As the package and its
 dependencies are unlikely to fit in any router with small flash (16MB or less),
 I don't see much point in making things configurable for reducing size either.
 
+### Vendor and product name
+
+`OTBR_VENDOR_NAME` and `OTBR_PRODUCT_NAME` have to be set: this release removed
+the built-in defaults, and otbr-agent exits with `Vendor name must be set.`
+without them.
+
+They are deliberately set to the values those defaults had, `OpenThread` and
+`BorderRouter`, rather than to something OpenWrt specific. The pair forms the
+MeshCoP service instance name as `<vendor> <product>`, which is the name shown
+when adding the border router in a Thread client and the one already-paired
+clients have recorded, so changing it would rename every existing user's border
+router on upgrade.
+
+### Version string
+
+`OTBR_VERSION` is set to `PKG_VERSION`. Without it the build falls back to the
+CMake project version, because the repacked source tree has no git directory
+for `git describe` to read, so `otbr-agent --version` and the `Running ...`
+line it logs on every start would report `0.3.0` rather than the release the
+package was built from.
+
+The version test in the package CI matches on that string, so dropping this
+option would make the package fail it again.
+
 ### Firewall support
 
 OpenWrt uses firewall4 with nftables by default, but the OpenThread firewall
@@ -35,17 +59,36 @@ Therefore, firewall support is disabled completely.
 This can be revised once the following feature request is implemented:
 https://github.com/openthread/ot-br-posix/issues/1675
 
-### mDNSResponder
+### mDNS
+
+The package uses OpenThread's internal mDNS implementation
+(`-DOTBR_MDNS=openthread`), which is upstream's default. This drops the
+mDNSResponder dependency entirely: no separate daemon, and no Avahi, whose
+libavahi-client requirement would have pulled in D-Bus.
+
+The internal implementation advertises on a single infrastructure interface,
+the one selected by the `backbone_network` option. Anything that needs to be
+announced on more than one interface still needs a general-purpose responder.
+
+It coexists with umdns, which remains the provider for other packages'
+services. Both bind the wildcard address on port 5353 with SO_REUSEADDR, which
+is what admits the second bind and gets multicast delivered to both, and they
+never contend for a name: OpenThread's mDNS names its host after the Thread
+extended address, while umdns keeps `<hostname>.local`.
 
-The package depends on mDNSResponder. The alternative, Avahi, depends on D-Bus,
-which is not something I feel comfortable with running on any router. While
-there are Avahi packages without D-Bus support, using OpenThread Border Router
-with Avahi requires libavahi-client, and this requires Avahi to be built with
-D-Bus support.
+Only multicast reaches both. A unicast datagram to port 5353 is delivered to
+one socket, so a unicast reply meant for one daemon can be received by the
+other. umdns does set SO_REUSEPORT, but only on a retry after its own bind
+fails, and that does not happen here because SO_REUSEADDR already admits the
+bind, so no SO_REUSEPORT group forms in either start order.
 
 ### REST Server
 
 The REST server is enabled to make this package compatible with Home Assistant.
+It listens on 127.0.0.1 by default. `rest_listen_address` and
+`rest_listen_port` can move it, but the API is unauthenticated and can read and
+replace the Thread dataset — including the network key — so any non-loopback
+address must be firewalled to trusted hosts.
 
 ### TREL support
 
@@ -83,14 +126,58 @@ config interface 'thread'
         option device 'wpan0'
         option proto 'openthread'
         option backbone_network 'lan'
-        option radio_url 'spinel+hdlc+uart:///dev/ttyACM0?uart-baudrate=460800'
+        option rcp '2-1'
+        option uart_baudrate '460800'
         list prefix 'fd6f:5772:5468:7200::/64 paros'
         option verbose '0'
 ```
 
-Prefix and verbose are optional. Everything else is required. The protocol
-handler will fail if a required setting is missing. If something isn't working,
-check ifstatus for the OpenThread interface:
+Only backbone_network and device are required. A radio need not be named at
+all: with neither rcp nor radio_url set the handler behaves as if `rcp 'any'`
+were given and auto-discovers a dongle, failing the interface with
+RCP_NOT_FOUND only when none is found. It also fails if backbone_network names
+an interface that has no device. Everything else — dataset, prefix, verbose,
+rest_listen_address and rest_listen_port — is optional. See
+[REST Server](#rest-server) before moving the REST API off the loopback
+default.
+
+### Finding the RCP
+
+The radio is named with the `rcp` option rather than a full radio URL. It takes
+one of three forms:
+
+| value | meaning |
+| --- | --- |
+| `/dev/ttyACM0` | a fixed serial device; no discovery is done |
+| `2-1` | a USB bus position, resolved to whatever serial device it currently exposes |
+| `any` (the default) | pick a dongle automatically |
+
+`uart_baudrate` and `uart_flow_control` are appended to the resulting URL, and
+the port is always opened exclusively. `uart_baudrate` is unset by default,
+leaving the port at otbr-agent's own default; `uart_flow_control` defaults to
+1, so hardware flow control is on unless it is set to 0. Turn it off for a
+3-wire UART, or for a dongle that never asserts CTS. Setting `radio_url`
+directly still works and overrides all of this.
+
+Discovery resolves USB dongles, which requires the cdc_acm driver: only an
+interface bound to it is accepted, and the `/dev/ttyACM*` node does not exist
+without it. Install `kmod-usb-acm` if it is not already present. A
+UART-attached radio named through `/dev/tty*` or `radio_url` needs none of
+this.
+
+Prefer a bus position to `any` unless the dongle advertises itself. Unattended
+selection only accepts a device whose USB product string contains the word
+"OpenThread", which many dongles — the Home Assistant Connect ZBT-2 among them
+— do not. Naming the bus position is the operator saying "this one is the RCP",
+so no product string is needed. `ls /sys/bus/usb/devices/` shows the positions.
+
+`otbr-rcp` also has a plugin point for installing or updating dongle firmware,
+used when `rcp_firmware_update` is set. It is off by default, and no handlers
+ship with this package, so nothing is flashed unless you both add a handler and
+ask for it.
+
+If something isn't working, check ifstatus for the OpenThread
+interface:
 
 ```
 # ifup thread
@@ -187,7 +274,8 @@ config interface 'thread'
         option backbone_network 'lan'
         option dataset '0e080000000000010000000300000f35060004001fffe0020836b86cd9746ab3080708fd9850cbe719b1d205101f11a11320828c7a6ebc2f2e675c0dca030e686f6d652d617373697374616e740102716f041025804ed78614258ebedf4e2db37b3b6e0c0402a0f7f8'
         list prefix 'fd6f:5772:5468:7200::/64 paros'
-        option radio_url 'spinel+hdlc+uart:///dev/ttyACM0?uart-baudrate=460800'
+        option rcp '2-1'
+        option uart_baudrate '460800'
         option verbose '0'
 ```
 

net/openthread-br/files/openthread-proto.sh

@@ -5,6 +5,7 @@
 
 OTCTL="/usr/sbin/ot-ctl"
 PROG="/usr/sbin/otbr-agent"
+RCP_PROG="/usr/sbin/otbr-rcp"
 
 [ -x "$PROG" ] || exit 0
 
@@ -21,25 +22,18 @@ proto_openthread_add_prefix() {
 	[ -n "$prefix" ] && $OTCTL prefix add $prefix
 }
 
-proto_openthread_check_service() {
-	service="$1"
-	ret=1
-	json_init
-	json_add_string name "$service"
-	ubus call service list "$(json_dump)" | jsonfilter -e '@[*].instances[*]["running"]' > /dev/null
-	ret=$?
-	json_cleanup
-
-	return "$ret"
-}
-
 proto_openthread_init_config() {
 	proto_config_add_array 'prefix:list(string)'
 	proto_config_add_boolean verbose
 	proto_config_add_string backbone_network
 	proto_config_add_string dataset
 	proto_config_add_string radio_url
-	proto_config_add_string foobar
+	proto_config_add_string rcp
+	proto_config_add_boolean rcp_firmware_update
+	proto_config_add_int uart_baudrate
+	proto_config_add_boolean uart_flow_control
+	proto_config_add_string rest_listen_address
+	proto_config_add_int rest_listen_port
 
 	available=1
 	no_device=1
@@ -55,29 +49,72 @@ proto_openthread_setup_error() {
 	exit 1
 }
 
+proto_openthread_setup_retry() {
+	# A missing RCP dongle is not a configuration error, but the interface
+	# must still be blocked: netifd re-runs a failed setup immediately and
+	# without backoff, which would busy-loop until a dongle appears. The
+	# hotplug handler's ifup lifts the block, so recovery is unaffected;
+	# this helper differs from proto_openthread_setup_error only in intent.
+	proto_openthread_setup_error "$@"
+}
+
 proto_openthread_setup() {
 	interface="$1"
 	device="$2"
 
 	mkdir -p /var/lib/thread
 
-	json_get_vars backbone_network dataset device radio_url verbose:0
+	json_get_vars backbone_network dataset device radio_url rcp \
+		rcp_firmware_update:0 uart_baudrate:0 uart_flow_control:1 \
+		rest_listen_address rest_listen_port verbose:0
 
 	[ -n "$backbone_network" ] || proto_openthread_setup_error "$interface" MISSING_BACKBONE_NETWORK
 	proto_add_host_dependency "$interface" "" "$backbone_network"
 	network_get_device backbone_ifname "$backbone_network"
 
 	[ -n "$backbone_ifname" ] || proto_openthread_setup_error "$interface" MISSING_BACKBONE_IFNAME
 	[ -n "$device" ] || proto_openthread_setup_error "$interface" MISSING_DEVICE
-	[ -n "$radio_url" ] || proto_openthread_setup_error "$interface" MISSING_RADIO_URL
-
-	# run in subshell to prevent wiping json data needed for prefixes
-	( proto_openthread_check_service mdnsd ) || proto_openthread_setup_error "$interface" MISSING_SVC_MDNSD
+	if [ -z "$radio_url" ]; then
+		case "$rcp" in
+		/dev/*)
+			# A fixed serial device needs no discovery.
+			radio_url="spinel+hdlc+uart://$rcp"
+			;;
+		*)
+			# Let otbr-rcp locate the dongle by its USB properties and,
+			# when a handler knows how, install or update its firmware.
+			# This runs here rather than under the launched command: a
+			# flash can take minutes, and it must not race the bounded
+			# wait for the agent's ubus object below.
+			#
+			# Pick the one value we need out of the output rather than
+			# evaluating it: otbr-rcp sources every firmware handler in
+			# /usr/share/openthread-rcp/, and a handler that prints to
+			# stdout would otherwise have its output run as root here.
+			RCPTTY="$("$RCP_PROG" \
+				$([ "$rcp_firmware_update" -eq 0 ] || echo --update) \
+				"${rcp:-any}" | sed -n 's/^RCPTTY=//p')"
+			[ -n "$RCPTTY" ] || \
+				proto_openthread_setup_retry "$interface" RCP_NOT_FOUND
+			radio_url="spinel+hdlc+uart://$RCPTTY"
+			;;
+		esac
+		radio_url="${radio_url}?uart-exclusive"
+		[ "$uart_baudrate" -eq 0 ] || radio_url="${radio_url}&uart-baudrate=${uart_baudrate}"
+		[ "$uart_flow_control" -eq 0 ] || radio_url="${radio_url}&uart-flow-control"
+	fi
 
 	opts="--auto-attach=0"
 	[ "$verbose" -eq 0 ] || append opts -v
 	append opts "-I$device"
 	append opts "-B$backbone_ifname"
+	# The REST API listens on 127.0.0.1 by default. Bind it elsewhere (e.g. a
+	# LAN address) to let remote clients such as Home Assistant reach it;
+	# leaving it unset keeps the loopback-only default. The REST API is
+	# unauthenticated and can both read and replace the Thread dataset, so any
+	# non-loopback address must be firewalled to trusted hosts.
+	[ -n "$rest_listen_address" ] && append opts "--rest-listen-address=$rest_listen_address"
+	[ -n "$rest_listen_port" ] && append opts "--rest-listen-port=$rest_listen_port"
 	append opts "$radio_url"
 	append opts "trel://$backbone_ifname"
 	# run in subshell to prevent wiping json data needed for prefixes