#!/bin/sh
# Copyright (C) 2016 Mathias Kresin <dev@kresin.me>

. /lib/functions.sh

# remove debug output from serial console
echo 5 > /proc/sys/kernel/printk

# check for required binaries
BINARIES="insmod flash_erase nandwrite ubirmvol nanddump openssl nandwrite fw_printenv fw_setenv"
for BINARY in ${BINARIES}; do
	[ ! -x $(which ${BINARY}) ] && {
		echo "${BINARY} not found - are you running the install image?" >&2
		exit 1
	}
done

# make sure expected partitions exist and are writable
PART_NAME="ubi"
UBI_PART_INDEX=$(find_mtd_index "${PART_NAME}")
[ -z "${UBI_PART_INDEX}" ] && {
	echo "${PART_NAME} partition not found - something is wrong!" >&2
	exit 1
}

[ $(cat /sys/class/block/mtdblock${UBI_PART_INDEX}/ro) -eq 1 ] && {
	echo "${PART_NAME} partition not writable - something is wrong!" >&2
	exit 1
}

PART_NAME="uboot-env"
UBOOT_ENV_PART_INDEX=$(find_mtd_index "${PART_NAME}")
[ -z "${UBOOT_ENV_PART_INDEX}" ] && {
	echo "${PART_NAME} partition not found - something is wrong!" >&2
	exit 1
}

[ $(cat /sys/class/block/mtdblock${UBOOT_ENV_PART_INDEX}/ro) -eq 1 ] && {
	echo "${PART_NAME} partition not writable - are you running the install image?" >&2
	exit 1
}

# cleanup nandsim state
rmmod nandsim &>/dev/null

# create 16 MByte virtual nand chip in RAM
insmod nandsim first_id_byte=0x20 second_id_byte=0x33 parts=8 >/dev/null
PART_NAME="NAND simulator partition 0"
NANDSIM_UBOOT_ENV_PART_INDEX=$(find_mtd_index "${PART_NAME}")
[ -z "${NANDSIM_UBOOT_ENV_PART_INDEX}" ] && {
	echo "ERROR ${PART_NAME} partition not found - something is wrong!" >&2
	exit 1
}

echo ""
echo "This script will erase parts of the Nand flash memory on this Hub, and then"
echo "prepare it for running Sysupgrade."
echo ""
echo ""
echo "WARNING: DO NOT CONTINUE unless you have saved a backup of the original firmware"
echo "         to your COMPUTER or other storage device!"
echo ""
echo ""
echo "DO NOT POWER OFF THE DEVICE DURING THIS PROCEDURE."
echo ""
echo ""

read -p "Please enter YESIHAVEABACKUP to continue: " CONFIRMATION
[ "${CONFIRMATION}" != "YESIHAVEABACKUP" ] && exit 0

set -o pipefail

echo ""
echo "Starting installation..."

# configure fw_printenv
echo "/dev/mtd${NANDSIM_UBOOT_ENV_PART_INDEX} 0x0000 0x20000 0x4000" > /etc/fw_env.config

# BT BusinessHub 5a
# Plusnet Hub One
# BT HomeHub 5a
KNOWN_KEYS="B1D3B4BD0970FCA9261E23C2170DB8E52407C71DAC06098678C0885BC7E68CCD \
	86fd5557bab554172a97eaec65680745d4ec2efe723decb956a50bd9bc13e1a8 \
	3E4CA8114D15BFC653B2BF9519EF2B94200E30345503B125C1D0BE776698B950"

for key in $KNOWN_KEYS; do
	echo "TRYING to decrypt u-boot env with key $key"

	# decrypt aes-256-cbc encrypted u-boot env and store to temporary mtd
	# blockdevice to manipulate it using the u-boot env tools
	flash_erase -q "/dev/mtd${NANDSIM_UBOOT_ENV_PART_INDEX}" 0 0

	nanddump -q "/dev/mtd${UBOOT_ENV_PART_INDEX}" | \
	openssl enc -d -aes-256-cbc \
		-K $key \
		-iv 00000000000000000000000000000000 -nopad | \
	nandwrite -q "/dev/mtd${NANDSIM_UBOOT_ENV_PART_INDEX}"

	BOOTCMD=$(fw_printenv -n bootcmd 2>/dev/null)
	[ -n "$BOOTCMD" ] && {
		echo "SUCCESSFULLY decrypted u-boot env"
		break
	}
done

if [ -z "$BOOTCMD" ]
then
	echo "WARNING: U-boot environment could not be decrypted!"
	echo ""
	echo "'bootcmd' will be reset to default values.  When the HH5A starts up after"
	echo "installing LEDE, the boot process will halt at the VR9# u-boot prompt."
	echo ""
	echo "To update 'bootcmd' variable refer to the guide on the web page hosting the"
	echo "install image."
	echo ""
	flash_erase "/dev/mtd${UBOOT_ENV_PART_INDEX}" 0 0

	read -p "Press any key to continue..."
else
	fw_printenv -n bootcmd_openrg &>/dev/null && {
		echo "ERROR bootcmd_openrg already exists. Please restore backup and start again" >&2
		exit 1
	}

	echo ""
	echo "BACKING UP original bootcmd in u-boot env"
	fw_setenv bootcmd_openrg "$BOOTCMD"

	echo "SETTING custom bootcmd in u-boot env"
	fw_setenv bootcmd 'ubi part UBI; ubi read $(loadaddr) kernel; bootm $(loadaddr)'

	echo "UNLOCKING u-boot prompt"
	fw_setenv silent

	echo ""
	echo "FLASHING updated encrypted u-boot env"
	flash_erase "/dev/mtd${UBOOT_ENV_PART_INDEX}" 0 0
	nanddump -q "/dev/mtd${NANDSIM_UBOOT_ENV_PART_INDEX}" | \
	openssl enc -aes-256-cbc \
		-K $key \
		-iv 00000000000000000000000000000000 -nopad | \
	nandwrite -m "/dev/mtd${UBOOT_ENV_PART_INDEX}"
fi

# cleanup nandsim state
rmmod nandsim &>/dev/null

echo ""
echo "REMOVING ubi volume OpenRG..."
ubirmvol /dev/ubi0 --name=OpenRG

echo ""
echo "REMOVING ubi volume FFS..."
ubirmvol /dev/ubi0 --name=FFS

echo ""
echo ""
echo "Preparation completed!"
echo ""
echo "Your attached USB media is mounted as a subdirectory at /tmp/mounts/"
echo ""
echo "To install LEDE, run:"
echo ""
echo "  sysupgrade /tmp/mounts/<directory>/lede-17.01.4-lantiq-xrx200-BTHOMEHUBV5A-squashfs-sysupgrade.bin"
echo ""
echo "Sysupgrade will automatically restart your device when it has finished."
echo "If the CFG-04 UART prompt appears, power-cycle your device!"
echo "The hub should now boot up using LEDE."