android: add port of wg-quick

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

contrib/android/README.md

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+# Tools for Android
+
+This currently contains a version of wg-quick.bash that works with
+Android 7's `ndc` command. It requires the WireGuard module to be
+part of your kernel, but after that, the usual `wg-quick up` and
+`wg-quick down` commands work normally.
+
+## Installation
+
+Build a `wg` binary for Android and place it in this folder. Then
+copy this folder some place on your phone, and run `sh ./install.sh`
+as root. It should survive ROM flashes.
+
+## Usage
+
+Compared to the ordinary wg-quick, this one gains a "DNS =" field,
+but loses SaveConfig and {Pre,Post}{Up,Down}.
+
+Put your configuration files into `/data/misc/wireguard/`. After that,
+the normal `wg-quick up|down` commands will work.
+

contrib/android/addonsd.sh

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+#!/sbin/sh
+
+. /tmp/backuptool.functions
+
+list_files() {
+cat <<_EOF
+xbin/wg
+xbin/wg-quick
+_EOF
+}
+
+case "$1" in
+	backup)
+		list_files | while read FILE DUMMY; do
+			backup_file $S/"$FILE"
+		done
+	;;
+	restore)
+		list_files | while read FILE REPLACEMENT; do
+			R=""
+			[ -n "$REPLACEMENT" ] && R="$S/$REPLACEMENT"
+			[ -f "$C/$S/$FILE" ] && restore_file $S/"$FILE" "$R"
+		done
+	;;
+	pre-backup)
+		# Stub
+	;;
+	post-backup)
+		# Stub
+	;;
+	pre-restore)
+		# Stub
+	;;
+	post-restore)
+		# Stub
+	;;
+esac

contrib/android/install.sh

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+#!/bin/sh
+mount -o rw,remount /system
+
+cp -v ./addonsd.sh /system/addon.d/40-wireguard.sh
+if [ -f ./wg ]; then
+	cp -v ./wg /system/xbin/wg
+else
+	echo "Warning: this directory does not contain wg. You may have forgotten to compile it yourself?" >&2
+fi
+cp -v ./wg-quick.bash /system/xbin/wg-quick
+chmod 755 /system/xbin/wg /system/xbin/wg-quick /system/addon.d/40-wireguard.sh
+mkdir -pvm 700 /data/misc/wireguard
+
+mount -o ro,remount /system

contrib/android/wg-quick.bash

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+#!/system/xbin/bash
+#
+# Copyright (C) 2016-2017 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
+#
+
+set -e -o pipefail
+shopt -s extglob
+export LC_ALL=C
+
+SELF="$(readlink -f "${BASH_SOURCE[0]}")"
+export PATH="${SELF%/*}:$PATH"
+
+WG_CONFIG=""
+INTERFACE=""
+NETID=0
+ADDRESSES=( )
+MTU=""
+DNS=""
+CONFIG_FILE=""
+PROGRAM="${0##*/}"
+ARGS=( "$@" )
+
+parse_options() {
+	local interface_section=0 line key value
+	CONFIG_FILE="$1"
+	[[ $CONFIG_FILE =~ ^[a-zA-Z0-9_=+.-]{1,16}$ ]] && CONFIG_FILE="/data/misc/wireguard/$CONFIG_FILE.conf"
+	[[ -e $CONFIG_FILE ]] || die "\`$CONFIG_FILE' does not exist"
+	[[ $CONFIG_FILE =~ /?([a-zA-Z0-9_=+.-]{1,16})\.conf$ ]] || die "The config file must be a valid interface name, followed by .conf"
+	((($(stat -c '%#a' "$CONFIG_FILE") & 0007) == 0)) || echo "Warning: \`$CONFIG_FILE' is world accessible" >&2
+	INTERFACE="${BASH_REMATCH[1]}"
+	shopt -s nocasematch
+	while read -r line || [[ -n $line ]]; do
+		key="${line%%=*}"; key="${key##*( )}"; key="${key%%*( )}"
+		value="${line#*=}"; value="${value##*( )}"; value="${value%%*( )}"
+		[[ $key == "["* ]] && interface_section=0
+		[[ $key == "[Interface]" ]] && interface_section=1
+		if [[ $interface_section -eq 1 ]]; then
+			case "$key" in
+			Address) ADDRESSES+=( ${value//,/ } ); continue ;;
+			MTU) MTU="$value"; continue ;;
+			DNS) DNS="$value"; continue ;;
+			esac
+		fi
+		WG_CONFIG+="$line"$'\n'
+	done < "$CONFIG_FILE"
+	shopt -u nocasematch
+}
+
+cmd() {
+	echo "[#] $*" >&2
+	"$@"
+}
+
+cndc() {
+	local out="$(cmd ndc "$@")"
+	[[ $out == *200\ 0* ]] || { echo "$out"; return 1; }
+}
+
+die() {
+	echo "$PROGRAM: $*" >&2
+	exit 1
+}
+
+auto_su() {
+	[[ $UID == 0 ]] || exec su -p -c "'$SELF' ${ARGS[*]}"
+}
+
+add_if() {
+	cmd ip link add "$INTERFACE" type wireguard
+}
+
+del_if() {
+	cmd ip link del "$INTERFACE"
+	[[ $(ip rule show) =~ 0xc([0-9a-f]+)/0xcffff\ lookup\ $INTERFACE ]] && cndc network destroy $(( 0x${BASH_REMATCH[1]} ));
+}
+
+up_if() {
+	while [[ $NETID -lt 4096 ]]; do
+		NETID="$RANDOM"
+	done
+	cmd wg set "$INTERFACE" fwmark 0x20000
+	cndc interface setcfg "$INTERFACE" up
+	cndc network create "$NETID" vpn 1 1
+	cndc network interface add "$NETID" "$INTERFACE"
+	cndc network users add "$NETID" 0-99999
+}
+
+set_dns() {
+	cndc resolver setnetdns "$NETID" "" "$1"
+}
+
+add_addr() {
+	if [[ $1 == *:* ]]; then
+		cndc interface ipv6 "$INTERFACE" enable
+		cmd ip -6 addr add "$1" dev "$INTERFACE"
+	else
+		local ip="${1%%/*}" mask=32
+		[[ $1 == */* ]] && mask="${1##*/}"
+		cndc interface setcfg "$INTERFACE" "$ip" "$mask"
+	fi
+}
+
+set_mtu() {
+	local mtu=0 endpoint output
+	if [[ -n $MTU ]]; then
+		cndc interface setmtu "$INTERFACE" "$MTU"
+		return
+	fi
+	while read -r _ endpoint; do
+		[[ $endpoint =~ ^\[?([a-z0-9:.]+)\]?:[0-9]+$ ]] || continue
+		output="$(ip route get "${BASH_REMATCH[1]}" || true)"
+		[[ ( $output =~ mtu\ ([0-9]+) || ( $output =~ dev\ ([^ ]+) && $(ip link show dev "${BASH_REMATCH[1]}") =~ mtu\ ([0-9]+) ) ) && ${BASH_REMATCH[1]} -gt $mtu ]] && mtu="${BASH_REMATCH[1]}"
+	done < <(wg show "$INTERFACE" endpoints)
+	if [[ $mtu -eq 0 ]]; then
+		read -r output < <(ip route show default || true) || true
+		[[ ( $output =~ mtu\ ([0-9]+) || ( $output =~ dev\ ([^ ]+) && $(ip link show dev "${BASH_REMATCH[1]}") =~ mtu\ ([0-9]+) ) ) && ${BASH_REMATCH[1]} -gt $mtu ]] && mtu="${BASH_REMATCH[1]}"
+	fi
+	[[ $mtu -gt 0 ]] || mtu=1500
+	cndc interface setmtu "$INTERFACE" $(( mtu - 80 ))
+}
+
+add_route() {
+	cndc network route add "$NETID" "$INTERFACE" "$1"
+}
+
+set_config() {
+	cmd wg setconf "$INTERFACE" <(echo "$WG_CONFIG")
+}
+
+cmd_usage() {
+	cat >&2 <<-_EOF
+	Usage: $PROGRAM [ up | down ] [ CONFIG_FILE | INTERFACE ]
+
+	  CONFIG_FILE is a configuration file, whose filename is the interface name
+	  followed by \`.conf'. Otherwise, INTERFACE is an interface name, with
+	  configuration found at /data/misc/wireguard/INTERFACE.conf. It is to be readable
+	  by wg(8)'s \`setconf' sub-command, with the exception of the following additions
+	  to the [Interface] section, which are handled by $PROGRAM:
+
+	  - Address: may be specified one or more times and contains one or more
+	    IP addresses (with an optional CIDR mask) to be set for the interface.
+	  - MTU: an optional MTU for the interface; if unspecified, auto-calculated.
+	  - DNS: an optional DNS server to use while the device is up.
+
+	See wg-quick(8) for more info and examples.
+	_EOF
+}
+
+cmd_up() {
+	local i
+	[[ -z $(ip link show dev "$INTERFACE" 2>/dev/null) ]] || die "\`$INTERFACE' already exists"
+	trap 'del_if; exit' INT TERM EXIT
+	add_if
+	set_config
+	set_mtu
+	for i in "${ADDRESSES[@]}"; do
+		add_addr "$i"
+	done
+	up_if
+	[[ -z $DNS ]] || set_dns "$DNS"
+	for i in $(while read -r _ i; do for i in $i; do [[ $i =~ ^[0-9a-z:.]+/[0-9]+$ ]] && echo "$i"; done; done < <(wg show "$INTERFACE" allowed-ips) | sort -nr -k 2 -t /); do
+		[[ $(ip route get "$i" 2>/dev/null) == *dev\ $INTERFACE\ * ]] || add_route "$i"
+	done
+	trap - INT TERM EXIT
+}
+
+cmd_down() {
+	[[ -n $(ip link show dev "$INTERFACE" type wireguard 2>/dev/null) ]] || die "\`$INTERFACE' is not a WireGuard interface"
+	del_if
+}
+
+if [[ $# -eq 1 && ( $1 == --help || $1 == -h || $1 == help ) ]]; then
+	cmd_usage
+elif [[ $# -eq 2 && $1 == up ]]; then
+	auto_su
+	parse_options "$2"
+	cmd_up
+elif [[ $# -eq 2 && $1 == down ]]; then
+	auto_su
+	parse_options "$2"
+	cmd_down
+else
+	cmd_usage
+	exit 1
+fi
+
+exit 0