simply to install vtun

vtun-install.sh

#!/bin/bash
RELEASE_API="https://api.github.com/repos/net-byte/vtun/releases/latest"
BIN_DST_DIR=/usr/local/bin
RESOURCE_DST_DIR=/usr/local/etc/vtun
CIDR_V4="192.168.90.0/24"
CIDR_V6="fced:9999::/64"
SIP_V4="192.168.90.1"
SIP_V6="fced:9999::1"
RUNNING_LISTENER="127.0.0.1:8002"
DEFAULT_KEY="defaultkey"

function getReleaseInfo() {
    response=$(curl ${RELEASE_API})
    if [ $? == 0 ]; then
        echo $response
        return 0
    else
        return 1
    fi      
}

function check_error() {
    if [ $? == 1 ]; then
        echo $1
        exit 1
    fi
}

function get_asset_name() {
    echo "vtun-$1-$2"
}

function install() {
    releaseData=$(getReleaseInfo)
    check_error "get release data error!"
    name=$(echo $releaseData | jq -r '.name')
    assets=$(echo $releaseData | jq -r '.assets')
    assetsSize=$(echo $releaseData | jq -r '.assets | length')
    expectedAssetName=$(get_asset_name linux amd64)
    expectedIndex=-1
    for i in $(seq 0 $(expr ${assetsSize} - 1))
    do
        currentAsset=$(echo $assets | jq -r ".[${i}]")
        currentAssetName=$(echo $currentAsset | jq -r '.name')
        if [[ ${expectedAssetName} = ${currentAssetName} ]]; then
            expectedIndex=$i
        fi
    done
    assetDownloadUrl=$(echo $assets | jq -r ".[$expectedIndex].browser_download_url")
    if [[ $assetDownloadUrl == '' ]]; then
        echo "get download url error!"
        exit 1
    fi
    echo $assetDownloadUrl
    wget -O ${BIN_DST_DIR}/vtun $assetDownloadUrl
    check_error "download binary error!"
    chmod +x ${BIN_DST_DIR}/vtun
    mkdir $RESOURCE_DST_DIR
    cat << EOT > /etc/systemd/system/vtun.service
[unit]
Description=vtun
Wants=network.target
After=syslog.target network-online.target
[Service]
Type=simple
Environment=GOGC=20
ExecStart=${BIN_DST_DIR}/vtun -S -c ${CIDR_V4} -c6 ${CIDR_V6} -sip ${SIP_V4} -sip6 ${SIP_V6} -p ws -l ${RUNNING_LISTENER} -k ${DEFAULT_KEY} -dn vt9
Restart=on-failure
RestartSec=10
KillMode=process
LimitNOFILE=65536
[Install]
WantedBy=multi-user.target
EOT
    systemctl enable --now vtun
    iptables -t nat -A POSTROUTING -j MASQUERADE
    check_error "iptables execuate error!"
    ip6tables -t nat -A POSTROUTING -j MASQUERADE
    check_error "ip6tables execuate error!"
    clear
    echo "running on ${RUNNING_LISTENER}"
    echo "key is ${DEFAULT_KEY}"
}

function remove() {
    iptables -t nat -D POSTROUTING -j MASQUERADE
    ip6tables -t nat -D POSTROUTING -j MASQUERADE
    systemctl stop vtun
    systemctl disable vtun
    rm -rf /etc/systemd/system/vtun.service
    rm -rf ${BIN_DST_DIR}/vtun
    rm -rf $RESOURCE_DST_DIR
    clear
    echo "remove finished!"
}

function help() {
    cat << EOF
    vtun install helper!!!
    usage: 
    ./vtun.sh menu
    install: install vtun
    remove: remove vtun
EOF
}

function main() {
    if [ $# -lt 1 ]; then
        help
    else
        case $1 in
            install)
                install
            ;;
            remove)
                remove
            ;;
            *)
                echo 'command not found!'
                help
            ;;
        esac
    fi
    exit 0
}

main $@