#!/bin/bash

################################################################################################
###   bash <(curl -fsSL https://raw.lhy.life/cf-doh.sh) --upstream=https://1.1.1.1/dns-query
################################################################################################


## GetArgValue <key> <defValue>
## ./script --key=value
g_args=("$@")
function GetArgValue()
{
    local key="$1"
    local defvalue="$2"

    for arg in "${g_args[@]}"
    do
        if [[ "$arg" == "--$key="* ]]
        then
            echo "${arg#*=}"
            return
        fi
    done

    echo "$defvalue"
}

UPSTREAM=$(GetArgValue "upstream" "https://1.1.1.1/dns-query")
UPSTREAM_TEMP=$(echo "$UPSTREAM" | grep -oP "https://\K[^/]+(?=/dns-query)") 

if [ -f "/root/apps/cloudflared/cloudflared" ]; then
    systemctl stop cloudflared-doh
    systemctl disable cloudflared-doh
    rm -rf /root/apps/cloudflared
    systemctl daemon-reload
fi

mkdir -p /root/apps/cloudflared && cd /root/apps/cloudflared

cp /etc/resolv.conf /etc/resolv.conf.bak
echo "nameserver $UPSTREAM_TEMP" > /etc/resolv.conf
wget -O "cloudflared" "https://github.com/cloudflare/cloudflared/releases/latest/download/cloudflared-linux-amd64"
chmod +x cloudflared

cat <<EOF > cloudflared-doh.service
[Unit]
Description=DNS over HTTPS (DoH) proxy client
Wants=network-online.target nss-lookup.target
Before=nss-lookup.target

[Service]
AmbientCapabilities=CAP_NET_BIND_SERVICE
CapabilityBoundingSet=CAP_NET_BIND_SERVICE
ExecStart=/root/apps/cloudflared/cloudflared proxy-dns --upstream $UPSTREAM --max-upstream-conns 0

[Install]
WantedBy=multi-user.target
EOF

ln -s /root/apps/cloudflared/cloudflared-doh.service /etc/systemd/system/cloudflared-doh.service
systemctl daemon-reload
systemctl restart cloudflared-doh
systemctl enable cloudflared-doh

if [ -f /etc/dhcp/dhclient.conf ]; then
    cp /etc/dhcp/dhclient.conf /etc/dhcp/dhclient.conf.bak
    sed -i "/^supersede domain-name-servers/d" /etc/dhcp/dhclient.conf
    echo 'supersede domain-name-servers 127.0.0.1;' >> /etc/dhcp/dhclient.conf
fi

echo 'nameserver 127.0.0.1' > /etc/resolv.conf
echo 'done'