main.sh

#!/bin/bash

trap 'cleanup; exit' SIGINT SIGTERM

red="\033[0;31m"
green="\033[0;32m"
yellow="\033[0;33m"
light_green="\033[38;5;50m"
reset="\033[0m"

cleanup() {
    printf "${yellow}Cleaning up processes...${reset}\n"
    kill "$req_pid" 2>/dev/null
    kill "$tcp_pid" 2>/dev/null
    kill "$ssh_pid" 2>/dev/null
    sleep 1
    kill $(pgrep -t $(tty | sed 's/\/dev\///') ssh) 2>/dev/null
}

check_network() {
    local url="https://www.google.com/generate_204"
    curl -sf --connect-timeout 5 "$url" &>/dev/null
}

keepalive() {
    local url=$(echo "$1" | tr -d '\n\r' | xargs)
    while true; do
        curl -Is $url | head -n 1 &>/dev/null
        sleep 120
    done
}

httptunnel() {
    local remote_port=80
    local subdomain="$4"
    local temp_file; temp_file=$(mktemp /tmp/tempfileXXXXXX.txt)

    if [[ -z "$subdomain" ]]; then
        printf "${green}Establishing HTTP tunnel with random subdomain...${reset}\n"
        ssh -nT -R "$remote_port:$host:$3" serveo.net | stdbuf -oL awk 'NR==1 {print $5}' > "$temp_file" &
        tunnel_pid=$!
    else
        printf "${green}Checking availability of subdomain '$subdomain'...${reset}\n"
        if wget --spider "https://$subdomain.serveo.net"; then
            printf "${red}Subdomain '$subdomain' is not available. Exiting.${reset}\n"
            rm "$temp_file"
            exit 1
        fi

        printf "${green}Establishing HTTP tunnel with subdomain '$subdomain'...${reset}\n"
        ssh -nT -R "$subdomain:$remote_port:$host:$3" serveo.net | stdbuf -oL awk 'NR==1 {print $5}' > "$temp_file" &
        tunnel_pid=$!
    fi

    while true; do
        if [[ -n "$link" ]]; then
            printf "${green}HTTP tunnel established: ${light_green}$link${reset}\n"
            url=$link
            link=""
            break
        else
            link=$(<"$temp_file")
        fi
        sleep 1
    done
    sleep 2

    rm "$temp_file"

    keepalive "$url" &
    req_pid=$!
}

tcptunnel() {
    local remote_port="${4:-0}"

    if [[ "$remote_port" -ne 0 ]] && ncat -zv serveo.net "$remote_port" &>/dev/null; then
        printf "${red}Remote port $remote_port is in use. Exiting.${reset}\n"
        exit 1
    fi

    printf "${green}Establishing TCP tunnel on port $remote_port...${reset}\n"
    ssh -nT -R "$remote_port:$host:$3" serveo.net &
    tcp_pid=$!

    sleep 5

    if ! ps -p $tcp_pid &>/dev/null; then
        printf "${red}Failed to establish TCP tunnel. Exiting.${reset}\n"
        exit 1
    fi

    printf "${green}TCP tunnel established successfully.${reset}\n"
}

sshtunnel() {
    printf "${green}Establishing SSH tunnel...${reset}\n"
    ssh -T -R "$3:22:$host:22" serveo.net &
    ssh_pid=$!

    sleep 5

    if ! ps -p $ssh_pid &>/dev/null; then
        printf "${red}Failed to establish SSH tunnel. Exiting.${reset}\n"
        exit 1
    fi

    printf "${green}SSH tunnel established successfully.${reset}\n"
}

restart_tunnel() {
    case "$opt" in
        1)
            httptunnel "$@"
            ;;
        2)
            tcptunnel "$@"
            ;;
        3)
            sshtunnel "$@"
            ;;
        *)
            printf "${red}Unknown tunnel option during restart. Exiting.${reset}\n"
            exit 1
            ;;
    esac
}

monitor_tunnels() {
    local first_warning=true
    while true; do
        if ! check_network; then
            printf "${yellow}Internet connection lost.${reset}\n"

            if $first_warning; then
                printf "${yellow}Waiting for internet connection...${reset}\n"
                first_warning=false
            fi

            until check_network; do
                sleep 5
            done

            printf "${green}Internet connection restored. Restarting tunnels...${reset}\n"
            first_warning=true
            sleep 10
            cleanup
            restart_tunnel "$@"
        fi

        if { [[ "$opt" -eq 1 ]] && ! ps -p "$tunnel_pid" &>/dev/null; } || \
           { [[ "$opt" -eq 2 ]] && ! ps -p "$tcp_pid" &>/dev/null; } || \
           { [[ "$opt" -eq 3 ]] && ! ps -p "$ssh_pid" &>/dev/null; }; then
            printf "${yellow}Tunnel process has stopped unexpectedly. Restarting...${reset}\n"
            cleanup
            restart_tunnel "$@"
        fi

        sleep 10
    done
}

main() {
    if ! check_network; then
        printf "${red}No internet connection. Exiting.${reset}\n"
        exit 1
    fi

    if [[ "$2" == "lh" ]]; then
        host="localhost"
    elif [[ -z $2 ]]; then
        printf "${red}Hostname not specified. Exiting.${reset}\n"
        exit 1
    else
        host="$2"
    fi

    case "$1" in
        http)
            opt=1
            [[ -z "$3" ]] && { printf "${red}Local port not specified. Exiting.${reset}\n"; exit 1; }
            httptunnel "$@"
            ;;
        tcp)
            opt=2
            [[ -z "$3" ]] && { printf "${red}Local port not specified. Exiting.${reset}\n"; exit 1; }
            tcptunnel "$@"
            ;;
        ssh)
            opt=3
            [[ -z "$3" ]] && { printf "${red}Public hostname alias not specified. Exiting.${reset}\n"; exit 1; }
            sshtunnel "$@"
            ;;
        *)
            printf "${red}Invalid protocol specified. Exiting.${reset}\n"
            exit 1
            ;;
    esac

    monitor_tunnels "$@"
}

main "$@"