Merge pull request #1 from oofnikj/rpi-zero

Add support for ARM (Raspberry Pi)

Dockerfile.rpi

@@ -0,0 +1,12 @@
+FROM scratch
+COPY . .
+ARG ROOT_PW
+RUN echo -e "${ROOT_PW}\n${ROOT_PW}" | passwd
+RUN mkdir -p /var/lock
+RUN opkg update && \
+    opkg install \
+      iperf3 \
+      ip-full && \
+    opkg list-upgradable | awk '{print $1}' | xargs opkg upgrade
+
+CMD [ "/sbin/init" ]

Makefile

@@ -1,13 +1,17 @@
-.PHONY: build run clean install uninstall
+.PHONY: build build-rpi run clean install uninstall
 
 include openwrt.conf
+export
 
 build:
-	@docker build \
-	  --build-arg ROOT_PW=${ROOT_PW} \
-		--build-arg OPENWRT_TAG=${OPENWRT_TAG} \
+	docker build \
+	  --build-arg ROOT_PW \
+		--build-arg OPENWRT_TAG \
 		-t ${BUILD_TAG} .
 
+build-rpi:
+	./build-rpi.sh ${RPI_SOURCE_IMG}
+
 run:
 	./run.sh
 

README.md

@@ -1,8 +1,8 @@
-# OpenWRT in Docker
+# OpenWrt in Docker
 
-Inspired by other projects that run `hostapd` in a Docker container. This goes one step further and boots a full network OS intended for embedded devices called [OpenWRT](https://openwrt.org/), so you can manage all aspects of your network from a user-friendly web UI.
+Inspired by other projects that run `hostapd` in a Docker container. This goes one step further and boots a full network OS intended for embedded devices called [OpenWrt](https://openwrt.org/), so you can manage all aspects of your network from a user-friendly web UI.
 
-I only tested this on x86_64, but it might work on ARM too with some minor tweaking.
+For Raspberry Pi-specific build instructions, see [Building on Raspberry Pi](./rpi.md).
 
 
 ## Dependencies
@@ -17,13 +17,13 @@ I only tested this on x86_64, but it might work on ARM too with some minor tweak
 ```
 $ make build
 ```
-If you want additional OpenWRT packages to be present in the base image, add them to the Dockerfile. Otherwise you can install them with `opkg` after bringing up the container.
+If you want additional OpenWrt packages to be present in the base image, add them to the Dockerfile. Otherwise you can install them with `opkg` after bringing up the container.
 
 A searchable package list is available on [openwrt.org](https://openwrt.org/packages/table/start).
 
 ## Configure
 
-Initial configuration is performed using a config file, `openwrt.conf`. Values read from this file at runtime are used to generate OpenWRT format config files.
+Initial configuration is performed using a config file, `openwrt.conf`. Values read from this file at runtime are used to generate OpenWrt format config files.
 
 To add or change the base configuration, modify the config templates in `etc/config/<section>.tpl`.
 
@@ -58,10 +58,8 @@ This will delete the container and all associated Docker networks so you can sta
 
 ### Hairpinning
 
-This took a couple of tries to get working. The most challenging issue was getting traffic from WLAN clients to reach each other.
 
-In order for this to work, OpenWRT bridges all interfaces in the LAN zone and sets hairpin mode (aka [reflective relay](https://lwn.net/Articles/347344/)) on the WLAN interface, meaning packets arriving on that interface can be 'reflected' back out through the same interface.
-OpenWRT is not able to set this mode from inside the container even with `NET_ADMIN` capabilities, so this must be done from the host. 
+In order for WLAN clients to see one another, OpenWrt bridges all interfaces in the LAN zone and sets hairpin mode (aka [reflective relay](https://lwn.net/Articles/347344/)) on the WLAN interface, meaning packets arriving on that interface can be 'reflected' back out through the same interface.
 
 `run.sh` tries to handle this, and prints a warning if it fails.
 

build-rpi.sh

@@ -0,0 +1,41 @@
+#!/bin/bash
+
+# Extracts the rootfs from OpenWRT Raspberry Pi image available from
+# https://downloads.openwrt.org/releases/19.07.2/targets/brcm2708/bcm2708/
+# and builds a Docker container out of it
+#
+# Refer to https://openwrt.org/toh/raspberry_pi_foundation/raspberry_pi
+# to choose the right image
+#
+# If building on x86, you must have qemu-arm and binfmt-support installed
+set -e
+
+IMG=${1:-'x'}
+
+
+mount_rootfs() {
+	echo "* mounting image"
+	offset=$(sfdisk -d ${IMG} | grep "${IMG}2" | sed -E 's/.*start=\s+([0-9]+).*/\1/g')
+	tmpdir=$(mktemp -u -p .)
+	mkdir -p "${tmpdir}"
+	sudo mount -o loop,offset=$((512 * $offset)) -t ext4 ${IMG} ${tmpdir}
+}
+
+docker_build() {
+	echo "* building Docker image"
+	sudo docker build \
+		--build-arg ROOT_PW="${ROOT_PW}" \
+		-t ${BUILD_TAG} -f Dockerfile.rpi ${tmpdir}
+}
+
+
+cleanup() {
+	echo "* cleaning up"
+	sudo umount ${tmpdir}
+	rm -rf ${tmpdir}
+}
+
+test -f ${IMG} || { echo 'no image file found'; exit 1; }
+trap cleanup EXIT
+mount_rootfs
+docker_build

openwrt.conf.example

@@ -1,24 +1,31 @@
 ### Sample OpenWRT config file ###
 
-# general
+## general
+# source image for Raspberry Pi build target
+SOURCE_IMG=openwrt-19.07.2-brcm2708-bcm2708-rpi-ext4-factory.img
+# source tag for build (x86) target
 OPENWRT_TAG=x86-64-19.07.2
+# final tag for built Docker image
 BUILD_TAG=openwrt
+# container name 
 CONTAINER=openwrt_1
 ROOT_PW=changeme123
 
 # docker network settings
 # wan
 WAN_NAME=openwrt-wan
-WAN_PARENT=enp0s20f0u4
+# host interface which will provide the WAN link for OpenWRT
+WAN_PARENT=eth0
 UPSTREAM_DNS_SERVER=8.8.8.8
 
-# lan
+# Static IP address configuration for OpenWRT LAN
 LAN_NAME=openwrt-lan
 LAN_DOMAIN=home
 LAN_SUBNET=192.168.16.0/24
 LAN6_SUBNET=fd99:1234::/48
+# Set LAN_ADDR to something other than the first available address
+# in the subnet - Docker will claim this address for the host
 LAN_ADDR=192.168.16.2
-LAN_HOST=192.168.16.1
 # openwrt doesn't accept CIDR notation; must match LAN_SUBNET
 LAN_NETMASK=255.255.255.0
 

rpi.md

@@ -0,0 +1,34 @@
+# Building on Raspberry Pi
+
+Turn your Pi into a pretty okay-ish travel router (or a very slow main router)!
+
+OpenWrt officially supports Raspberry Pi hardware if you want to run it as your OS. But running in a container brings many advantages, one of which is not having to re-flash your SD card.
+
+This has been tested on a Raspberry Pi Zero W running Raspbian Lite, but should work for other versions too. Just make sure you download the right image for your Pi version (refer to the notes in [build-rpi.sh](./build-rpi.sh)).
+
+
+## IPv6
+By default Raspbian does not load the kernel module for IPv6 `iptables` on boot.
+
+Run `sudo modprobe ip6_tables` to load it immediately.
+
+To persist on reboot, run
+
+    $ echo 'ip6_tables' | sudo tee /etc/modules-load.d/ip6-tables.conf
+
+---
+## Build 
+You can build the OpenWRT docker image on the Pi itself, or on your x86 PC with `qemu-arm` installed.
+
+First download and extract the OpenWRT factory image for your Pi. Refer to the [OpenWrt Table of Hardware](https://openwrt.org/toh/raspberry_pi_foundation/raspberry_pi) to choose the right image. Then run the `make` target.
+
+The variable `RPI_SOURCE_IMG` can be specified in openwrt.conf or on the command line:
+```
+$ https://downloads.openwrt.org/releases/19.07.2/targets/brcm2708/bcm2708/openwrt-19.07.2-brcm2708-bcm2708-rpi-ext4-factory.img.gz
+$ gzip -d openwrt-*.img.gz
+$ make build-rpi RPI_SOURCE_IMG=openwrt-19.07.2-brcm2708-bcm2708-rpi-ext4-factory.img
+```
+
+If you built the image on your PC, send it to your Raspberry Pi (`$BUILD_TAG` is a config variable):
+```
+$ docker save $BUILD_TAG | ssh <your_raspberry_pi_host> docker load

run.sh

@@ -69,7 +69,7 @@ function _set_hairpin() {
   for i in {1..10}; do
     echo -n '.'
     sudo ip netns exec $CONTAINER ip link set $WIFI_IFACE type bridge_slave hairpin on 2>/dev/null && { echo 'ok'; break; }
-    sleep 1
+    sleep 3
   done
   if [[ $i -ge 10 ]]; then
     echo -e "\ncouldn't set hairpin mode, wifi clients will probably be unable to talk to each other"
@@ -78,8 +78,8 @@ function _set_hairpin() {
 
 function _create_or_start_container() {
   docker inspect $BUILD_TAG >/dev/null 2>&1 || { echo "no image '$BUILD_TAG' found, did you forget to run 'make build'?"; exit 1; }
-  docker inspect $CONTAINER >/dev/null 2>&1
-  if [[ $? -eq 0 ]]; then
+  
+  if docker inspect $CONTAINER >/dev/null 2>&1; then
     echo "* starting container '$CONTAINER'"
     docker start $CONTAINER
   else
@@ -103,9 +103,20 @@ function _create_or_start_container() {
   fi
 }
 
+function _reload_fw() {
+  echo "* reloading firewall rules"
+  docker exec -it $CONTAINER sh -c '
+    for iptables in iptables ip6tables; do
+      for table in filter nat mangle; do
+        $iptables -t $table -F
+      done
+    done
+    /sbin/fw3 -q restart'
+}
+
 function main() {
   test -z $WIFI_IFACE && _usage
-  cd $SCRIPT_DIR
+  cd "${SCRIPT_DIR}"
   _get_phy_from_dev
   _nmcli
   _create_or_start_container
@@ -124,6 +135,7 @@ function main() {
   echo "* getting address via DHCP"
   sudo dhcpcd -q "br-${LAN_ID:0:12}"
   
+  _reload_fw
   echo "* ready"
 }