#!/usr/bin/env bash
#
# usage update-blacklist.sh <configuration file>
# eg: update-blacklist.sh /etc/ipset-blacklist/ipset-blacklist.conf
#
function exists() { command -v "$1" >/dev/null 2>&1; }

if [[ -z "$1" ]]; then
    echo "Error: please specify a configuration file, e.g. $0 /etc/ipset-blacklist/ipset-blacklist.conf"
    exit 1
fi

# shellcheck source=ipset-blacklist.conf
if ! source "$1"; then
    echo "Error: can't load configuration file $1"
    exit 1
fi

if ! exists curl && exists egrep && exists grep && exists ipset && exists iptables && exists sed && exists sort && exists wc; then
    echo >&2 "Error: searching PATH fails to find executables among: curl egrep grep ipset iptables sed sort wc"
    exit 1
fi

DO_OPTIMIZE_CIDR=no
if exists iprange && [[ ${OPTIMIZE_CIDR:-yes} != no ]]; then
    DO_OPTIMIZE_CIDR=yes
fi

if [[ ! -d $(dirname "$IP_BLACKLIST") || ! -d $(dirname "$IP_BLACKLIST_RESTORE") ]]; then
    echo >&2 "Error: missing directory(s): $(dirname "$IP_BLACKLIST" "$IP_BLACKLIST_RESTORE" | sort -u)"
    exit 1
fi

# create the ipset if needed (or abort if does not exists and FORCE=no)
if ! ipset list -n | command grep -q "$IPSET_BLACKLIST_NAME"; then
    if [[ ${FORCE:-no} != yes ]]; then
        echo >&2 "Error: ipset does not exist yet, add it using:"
        echo >&2 "# ipset create $IPSET_BLACKLIST_NAME -exist hash:net family inet hashsize ${HASHSIZE:-16384} maxelem ${MAXELEM:-65536}"
        exit 1
    fi

    if ! ipset create "$IPSET_BLACKLIST_NAME" -exist hash:net family inet hashsize "${HASHSIZE:-16384}" maxelem "${MAXELEM:-65536}"; then
        echo >&2 "Error: while creating the initial ipset"
        exit 1
    fi
fi

# create the iptables binding if needed (or abort if does not exists and FORCE=no)
if ! iptables -nvL INPUT | command grep -q "match-set $IPSET_BLACKLIST_NAME"; then
    # we may also have assumed that INPUT rule n°1 is about packets statistics (traffic monitoring)
    if [[ ${FORCE:-no} != yes ]]; then
        echo >&2 "Error: iptables does not have the needed ipset INPUT rule, add it using:"
        echo >&2 "# iptables -I INPUT ${IPTABLES_IPSET_RULE_NUMBER:-1} -m set --match-set $IPSET_BLACKLIST_NAME src -j DROP"
        exit 1
    fi

    if ! iptables -I INPUT "${IPTABLES_IPSET_RULE_NUMBER:-1}" -m set --match-set "$IPSET_BLACKLIST_NAME" src -j DROP; then
        echo >&2 "Error: while adding the --match-set ipset rule to iptables"
        exit 1
    fi
fi

IP_BLACKLIST_TMP=$(mktemp)
for i in "${BLACKLISTS[@]}"; do
    IP_TMP=$(mktemp)
    ((HTTP_RC = $(curl -L -A "blacklist-update/script/github" --connect-timeout 10 --max-time 10 -o "$IP_TMP" -s -w "%{http_code}" "$i")))
    if ((HTTP_RC == 200 || HTTP_RC == 302 || HTTP_RC == 0)); then # "0" because file:/// returns 000
        command grep -Po '^(?:\d{1,3}\.){3}\d{1,3}(?:/\d{1,2})?' "$IP_TMP" | sed -r 's/^0*([0-9]+)\.0*([0-9]+)\.0*([0-9]+)\.0*([0-9]+)$/\1.\2.\3.\4/' >>"$IP_BLACKLIST_TMP"
        [[ ${VERBOSE:-yes} == yes ]] && echo -n "."
    elif ((HTTP_RC == 503)); then
        echo -e "\\nUnavailable (${HTTP_RC}): $i"
    else
        echo >&2 -e "\\nWarning: curl returned HTTP response code $HTTP_RC for URL $i"
    fi

    rm -f "$IP_TMP"
done

# sort -nu does not work as expected
sed -r -e '/^(0\.0\.0\.0|10\.|127\.|172\.1[6-9]\.|172\.2[0-9]\.|172\.3[0-1]\.|192\.168\.|22[4-9]\.|23[0-9]\.)/d' "$IP_BLACKLIST_TMP" | sort -n | sort -mu >|"$IP_BLACKLIST"
if [[ ${DO_OPTIMIZE_CIDR} == yes ]]; then
    if [[ ${VERBOSE:-no} == yes ]]; then
        echo -e "\\nAddresses before CIDR optimization: $(wc -l "$IP_BLACKLIST" | cut -d' ' -f1)"
    fi

    iprange <"$IP_BLACKLIST" --optimize - >"$IP_BLACKLIST_TMP" 2>/dev/null
    if [[ ${VERBOSE:-no} == yes ]]; then
        echo "Addresses after CIDR optimization:  $(wc -l "$IP_BLACKLIST_TMP" | cut -d' ' -f1)"
    fi

    cp "$IP_BLACKLIST_TMP" "$IP_BLACKLIST"
fi

rm -f "$IP_BLACKLIST_TMP"

# family = inet for IPv4 only
cat >|"$IP_BLACKLIST_RESTORE" <<EOF
create $IPSET_TMP_BLACKLIST_NAME -exist hash:net family inet hashsize ${HASHSIZE:-16384} maxelem ${MAXELEM:-65536}
create $IPSET_BLACKLIST_NAME -exist hash:net family inet hashsize ${HASHSIZE:-16384} maxelem ${MAXELEM:-65536}
EOF

# can be IPv4 including netmask notation
# IPv6 ? -e "s/^([0-9a-f:./]+).*/add $IPSET_TMP_BLACKLIST_NAME \1/p" \ IPv6
sed -rn -e '/^#|^$/d' \
    -e "s/^([0-9./]+).*/add $IPSET_TMP_BLACKLIST_NAME \\1/p" "$IP_BLACKLIST" >>"$IP_BLACKLIST_RESTORE"

cat >>"$IP_BLACKLIST_RESTORE" <<EOF
swap $IPSET_BLACKLIST_NAME $IPSET_TMP_BLACKLIST_NAME
destroy $IPSET_TMP_BLACKLIST_NAME
EOF

ipset -file "$IP_BLACKLIST_RESTORE" restore

if [[ ${VERBOSE:-no} == yes ]]; then
    echo
    echo "Blacklisted addresses found: $(wc -l "$IP_BLACKLIST" | cut -d' ' -f1)"
fi