go-go-gadget

#!/bin/bash
# Source: https://www.hardill.me.uk/wordpress/2019/11/02/pi4-usb-c-gadget/
RED="\e[1;31m"
YLW="\e[1;33m"
FIN="\e[0m"

run_as_root(){
if [ "$USER" != "root" ]; then
        echo "Please run this as root or with sudo privileges."
        exit 1
fi
}

internet_check(){
if wget -q --spider http://github.com; then :; else echo -e "This script requires an internet connection." && exit 1; fi
}

confirm(){
echo -e "${YLW}If you have no clue as to what USB Gadget"
echo -e "mode is, then please do not run this script${FIN}."
echo -e ""
read -p "Continue (y/n)?" choice
case "$choice" in 
  y|Y ) echo && echo -e "${RED}Confirmed${FIN}!";;
  n|N ) echo && echo -e "${YLW}You have chosen${FIN}... ${YLW}wisely${FIN}." && exit 0;;
  * ) echo && echo -e "${YLW}Invalid choice${FIN}." && exit 0;;
esac
}

setup_overlays(){
sed -i "1 s|$| modules-load=dwc2,g_ether|" "/boot/cmdline.txt"
echo -e "" >> /boot/config.txt && echo -e "# enable USB OTG" >> /boot/config.txt
echo "dtoverlay=dwc2,dr_mode=peripheral" >> /boot/config.txt
echo "libcomposite" >> /etc/modules
}

install_dnsmasq(){
sudo apt update
sudo apt upgrade -y
sudo apt install dnsmasq -y
}

create_usb0(){
mkdir -p /etc/dnsmasq.d
tee /etc/dnsmasq.d/usb <<EOF
interface=usb0
dhcp-range=10.55.0.2,10.55.0.6,255.255.255.248,1h
dhcp-option=3,10.55.0.1
leasefile-ro
EOF

mkdir -p /etc/network/interfaces.d/
tee /etc/network/interfaces.d/usb0 <<EOF
auto usb0
allow-hotplug usb0
iface usb0 inet static
  address 10.55.0.1
  netmask 255.255.255.248
EOF
}

create_gadget_script(){
tee /usr/local/sbin/gadget-mode <<EOF
#!/bin/bash
cd /sys/kernel/config/usb_gadget/
mkdir -p pi4
cd pi4
echo 0x1d6b > idVendor # Linux Foundation
echo 0x0104 > idProduct # Multifunction Composite Gadget
echo 0x0100 > bcdDevice # v1.0.0
echo 0x0200 > bcdUSB # USB2
echo 0xEF > bDeviceClass
echo 0x02 > bDeviceSubClass
echo 0x01 > bDeviceProtocol
mkdir -p strings/0x409
echo "fedcba9876543211" > strings/0x409/serialnumber
echo "Ben Hardill" > strings/0x409/manufacturer
echo "PI4 USB Device" > strings/0x409/product
mkdir -p configs/c.1/strings/0x409
echo "Config 1: ECM network" > configs/c.1/strings/0x409/configuration
echo 250 > configs/c.1/MaxPower
# Add functions here
# see gadget configurations below
# End functions
mkdir -p functions/ecm.usb0
HOST="00:dc:c8:f7:75:14" # "HostPC"
SELF="00:dd:dc:eb:6d:a1" # "BadUSB"
echo $HOST > functions/ecm.usb0/host_addr
echo $SELF > functions/ecm.usb0/dev_addr
ln -s functions/ecm.usb0 configs/c.1/
udevadm settle -t 5 || :
ls /sys/class/udc > UDC
ifup usb0
service dnsmasq restart
EOF
chown root:root /usr/local/sbin/gadget-mode
chmod +x /usr/local/sbin/gadget-mode
}

create_gadget_service(){
tee /etc/systemd/system/gadget.service <<EOF
[Unit]
Description=Enable Gadget Mode
ConditionPathExists=/usr/local/sbin/gadget-mode
After=systemd-modules-load.service

[Service]
ExecStart=/usr/local/sbin/gadget-mode &>/dev/null
Type=oneshot
RemainAfterExit=yes

[Install]
WantedBy=sysinit.target
EOF
systemctl enable gadget
}

add_gadget_init(){
wget -cq --show-progress https://github.com/pyavitz/scripts/raw/master/gadget.init -P /etc/init.d/
if [ -e /etc/init.d/gadget.init ];
   then mv -f /etc/init.d/gadget.init /etc/init.d/gadget;
   else echo -e "Gadget init install failed!" && exit 0;
fi
if [ -e /etc/init.d/gadget ];
   then chmod +x /etc/init.d/gadget && update-rc.d gadget defaults 2
fi
}

# The Magic
internet_check
run_as_root
echo
confirm

echo
echo -e "Pi4 USB-C Gadget Setup"
echo
echo -e "Installing dnsmasq ..."
install_dnsmasq
echo -e "Done."

echo
echo -e "Setting up overlays ..."
setup_overlays > /dev/null 2>&1
sleep 1s
echo -e "Done."

echo
echo -e "Creating usb0 file ..."
create_usb0 > /dev/null 2>&1
sleep 1s
echo -e "Done."

echo
echo -e "Creating gadget script ..."
create_gadget_script > /dev/null 2>&1
sleep 1s
echo -e "Done."

echo
echo -e "Creating gadget service ..."
if [ -e /etc/devuan_version ];
   then add_gadget_init;
   else create_gadget_service > /dev/null 2>&1;
fi
sleep 1s
echo -e "Done."

echo
echo -e "Install complete!"
echo
echo -e "Your Pi will show up as a ethernet device with an IP address of 10.55.0.1"
echo -e "and should assign the device you plug it into an IP address via DHCP. This"
echo -e "means you can just ssh to username@10.55.0.1 to start using it."
echo