#!/bin/sh
# Wrapper for acme.sh to work on openwrt.
#
# This program is free software; you can redistribute it and/or modify it under
# the terms of the GNU General Public License as published by the Free Software
# Foundation; either version 3 of the License, or (at your option) any later
# version.
#
# Author: Toke Høiland-Jørgensen <toke@toke.dk>

CHECK_CRON=$1
ACME=/usr/lib/acme/acme.sh
export CURL_CA_BUNDLE=/etc/ssl/certs/ca-certificates.crt
export NO_TIMESTAMP=1

UHTTPD_LISTEN_HTTP=
STATE_DIR='/etc/acme'
ACCOUNT_EMAIL=
DEBUG=0

. /lib/functions.sh

check_cron()
{
    [ -f "/etc/crontabs/root" ] && grep -q '/etc/init.d/acme' /etc/crontabs/root && return
    echo "0 0 * * * /etc/init.d/acme start" >> /etc/crontabs/root
    /etc/init.d/cron start
}

log()
{
    logger -t acme -s -p daemon.info "$@"
}

err()
{
    logger -t acme -s -p daemon.err "$@"
}

debug()
{
    [ "$DEBUG" -eq "1" ] && logger -t acme -s -p daemon.debug "$@"
}

get_listeners()
{
    netstat -nptl 2>/dev/null | awk 'match($4, /:80$/){split($7, parts, "/"); print parts[2];}' | uniq | tr "\n" " "
}

pre_checks()
{
    main_domain="$1"

    log "Running pre checks for $main_domain."

    listeners="$(get_listeners)"
    debug "port80 listens: $listeners"

    case "$listeners" in
        "uhttpd")
            debug "Found uhttpd listening on port 80; trying to disable."

            UHTTPD_LISTEN_HTTP=$(uci get uhttpd.main.listen_http)

            if [ -z "$UHTTPD_LISTEN_HTTP" ]; then
                err "$main_domain: Unable to find uhttpd listen config."
                err "Manually disable uhttpd or set webroot to continue."
                return 1
            fi

            uci set uhttpd.main.listen_http=''
            uci commit uhttpd || return 1
            if ! /etc/init.d/uhttpd reload ; then
                uci set uhttpd.main.listen_http="$UHTTPD_LISTEN_HTTP"
                uci commit uhttpd
                return 1
            fi
            ;;
        "")
            debug "Nothing listening on port 80."
            ;;
        *)
            err "$main_domain: Cannot run in standalone mode; another daemon is listening on port 80."
            err "Disable other daemon or set webroot to continue."
            return 1
            ;;
    esac

    iptables -I input_rule -p tcp --dport 80 -j ACCEPT -m comment --comment "ACME" || return 1
    ip6tables -I input_rule -p tcp --dport 80 -j ACCEPT -m comment --comment "ACME" || return 1
    debug "v4 input_rule: $(iptables -nvL input_rule)"
    debug "v6 input_rule: $(ip6tables -nvL input_rule)"
    return 0
}

post_checks()
{
    log "Running post checks (cleanup)."
    # The comment ensures we only touch our own rules. If no rules exist, that
    # is fine, so hide any errors
    iptables -D input_rule -p tcp --dport 80 -j ACCEPT -m comment --comment "ACME" 2>/dev/null
    ip6tables -D input_rule -p tcp --dport 80 -j ACCEPT -m comment --comment "ACME" 2>/dev/null

    if [ -e /etc/init.d/uhttpd ] && [ -n "$UHTTPD_LISTEN_HTTP" ]; then
        uci set uhttpd.main.listen_http="$UHTTPD_LISTEN_HTTP"
        uci commit uhttpd
        /etc/init.d/uhttpd reload
        UHTTPD_LISTEN_HTTP=
    fi
}

err_out()
{
    post_checks
    exit 1
}

int_out()
{
    post_checks
    trap - INT
    kill -INT $$
}

is_staging()
{
    local main_domain="$1"

    grep -q "acme-staging" "$STATE_DIR/$main_domain/${main_domain}.conf"
    return $?
}

issue_cert()
{
    local section="$1"
    local acme_args=
    local enabled
    local use_staging
    local update_uhttpd
    local keylength
    local domains
    local main_domain
    local moved_staging=0
    local failed_dir
    local webroot

    config_get_bool enabled "$section" enabled 0
    config_get_bool use_staging "$section" use_staging
    config_get_bool update_uhttpd "$section" update_uhttpd
    config_get domains "$section" domains
    config_get keylength "$section" keylength
    config_get webroot "$section" webroot

    [ "$enabled" -eq "1" ] || return

    [ "$DEBUG" -eq "1" ] && acme_args="$acme_args --debug"

    set -- $domains
    main_domain=$1

    [ -n "$webroot" ] || pre_checks "$main_domain" || return 1

    log "Running ACME for $main_domain"

    if [ -e "$STATE_DIR/$main_domain" ]; then
        if [ "$use_staging" -eq "0" ] && is_staging "$main_domain"; then
            log "Found previous cert issued using staging server. Moving it out of the way."
            mv "$STATE_DIR/$main_domain" "$STATE_DIR/$main_domain.staging"
            moved_staging=1
        else
            log "Found previous cert config. Issuing renew."
            $ACME --home "$STATE_DIR" --renew -d "$main_domain" $acme_args || return 1
            return 0
        fi
    fi


    acme_args="$acme_args $(for d in $domains; do echo -n "-d $d "; done)"
    acme_args="$acme_args --keylength $keylength"
    [ -n "$ACCOUNT_EMAIL" ] && acme_args="$acme_args --accountemail $ACCOUNT_EMAIL"
    [ "$use_staging" -eq "1" ] && acme_args="$acme_args --staging"

    if [ -z "$webroot" ]; then
        log "Using standalone mode"
        acme_args="$acme_args --standalone"
    else
        if [ ! -d "$webroot" ]; then
            err "$main_domain: Webroot dir '$webroot' does not exist!"
            return 1
        fi
        log "Using webroot dir: $webroot"
        acme_args="$acme_args --webroot \"$webroot\""
    fi

    if ! $ACME --home "$STATE_DIR" --issue $acme_args; then
        failed_dir="$STATE_DIR/${main_domain}.failed-$(date +%s)"
        err "Issuing cert for $main_domain failed. Moving state to $failed_dir"
        [ -d "$STATE_DIR/$main_domain" ] && mv "$STATE_DIR/$main_domain" "$failed_dir"
        if [ "$moved_staging" -eq "1" ]; then
            err "Restoring staging certificate"
            mv "$STATE_DIR/${main_domain}.staging" "$STATE_DIR/${main_domain}"
        fi
        return 1
    fi

    if [ "$update_uhttpd" -eq "1" ]; then
        uci set uhttpd.main.key="$STATE_DIR/${main_domain}/${main_domain}.key"
        uci set uhttpd.main.cert="$STATE_DIR/${main_domain}/fullchain.cer"
        # commit and reload is in post_checks
    fi

    post_checks
}

load_vars()
{
    local section="$1"

    STATE_DIR=$(config_get "$section" state_dir)
    ACCOUNT_EMAIL=$(config_get "$section" account_email)
    DEBUG=$(config_get "$section" debug)
}

check_cron
[ -n "$CHECK_CRON" ] && exit 0

config_load acme
config_foreach load_vars acme

if [ -z "$STATE_DIR" ] || [ -z "$ACCOUNT_EMAIL" ]; then
    err "state_dir and account_email must be set"
    exit 1
fi

[ -d "$STATE_DIR" ] || mkdir -p "$STATE_DIR"

trap err_out HUP TERM
trap int_out INT

config_foreach issue_cert cert

exit 0