Easy vpnbook Credentials Grabber [ command line ]

#!/bin/sh
# ImPerial TeK. Solutions (ITS)
# Copyright (c) 2018 v1ral <ImPerialTeKSolutions@outlook.com>

PROGRAM="vpnbook"
# URL to the site containing user and password
SITE="https://www.vpnbook.com/freevpn"
# URL to the site containing OpenVPN configs
OPENVPN_SITE="https://www.vpnbook.com"
# File where VPNBook credentials get stored
AUTH_FILE="./vpnbook.auth"
# Path to temporary file
AUTH_FILE_TMP="/tmp/vpnbook.$$"
# Folder where OpenVPN configs are created
CONFIG_FOLDER="./"
# Path to temporary folder for config generation
CONFIG_FOLDER_TEMP="/tmp/vpnbook-config.$$"

cleanup() {
    rm -f "$AUTH_FILE_TMP"
    rm -rf "$CONFIG_FOLDER_TEMP"
}

trap cleanup HUP INT TERM

usage() {
    cat << EOF
Usage: $PROGRAM <command> [parameter]
Commands are
    config  Generate OpenVPN configs for non-interactive usage based on configs provided
            on $OPENVPN_SITE
    auth    Extract user and password from $OPENVPN_SITE and save to auth-user-pass file
            (default: $AUTH_FILE)
Parameters are
    -a <file>    Path to the auth_user_pass file (default: $AUTH_FILE)
    -c <folder>  Folder where OpenVPN configs are generated (default: $CONFIG_FOLDER)
    -h           Show this help
EOF
}

download_site() {
    local site="$1"
    curl "$site" -s
}

extract_credentials() {
    awk -F '[<>]' '
    BEGIN { exit_value = 1 }
    /Username:/ && !user_found { print $5; user_found = 1; next }
    /Password:/ && user_found { print $5; exit_value = 0; exit }
    END { exit exit_value }
    '
}

extract_config_urls() {
    local site="$1"
    awk -F '[<>]' -v site=$site '
    /free-openvpn-account/ { split($4, a, /"/); print site a[2] }
    '
}

generate_auth() {
    local data="$1"
    if (echo "$data" | extract_credentials) > "$AUTH_FILE_TMP"; then
        mv "$AUTH_FILE_TMP" "$AUTH_FILE"
        chmod 600 "$AUTH_FILE"
    fi
}

generate_vpn_config() {
    awk -v auth_file="$AUTH_FILE" '
    # Remove windows newline
    { sub(/\r$/, "") }
    # Add both ports in config file and let OpenVPN select them remote-random
    /^remote/ {
        host = $2; print
        print $1, host, 25000
        if (!remote_random_printed) {
            print "remote-random"
            remote_random_printed = 1
        }
        next
    }
    # Switch authentication from interactive to file based
    /^auth-user-pass/ {
        print $1, auth_file
        print "auth-retry nointeract"
        next
    }
    # Let OpenVPN check the remote certificate
    /^<ca>/ {
        print "ns-cert-type server"
    }
    # Output everything else unchanged
    { print }
    '
}

generate_config() {
    local data="$1"
    mkdir "$CONFIG_FOLDER_TEMP" || return
    for url in $(echo "$site_data" | extract_config_urls "$OPENVPN_SITE"); do
        local file="$CONFIG_FOLDER_TEMP/${url##*/}"
        local conf_file="vpnbook-${file##*-}"
        conf_file=${conf_file%.zip}.ovpn
        conf_file="$CONFIG_FOLDER/$(echo $conf_file | tr 'A-Z' 'a-z')"
        curl "$url" -o "$file" -s
        unzip -p "$file"  '*udp53*.ovpn' | generate_vpn_config > "$conf_file"
    done

    generate_auth "$data"
}

main() {
    case $1 in
        config | auth )
            generator_func="generate_$1"
            ;;
        * )
            usage
            exit 1
            ;;
    esac
    shift

    while getopts 'a:c:h' options; do
        case $options in
            a )
                auth_file=$OPTARG
                ;;
            c )
                config_folder=$OPTARG
                ;;
            h | \?)
                usage
                exit 1
                ;;
        esac
    done

    AUTH_FILE=${auth_file:-$AUTH_FILE}
    CONFIG_FOLDER=${config_folder:-$CONFIG_FOLDER}

    local site_data="$(download_site "$SITE")"
    $generator_func "$site_data"
    retval=$?
    cleanup
    return $retval
}

if [ "$PROGRAM" = ${0##*/} ]; then
    main "$@"
    exit $?
fi