#!/usr/bin/bash

# check for nmap and jq
# check for root

if [ -f arpscan.json ]
then
    tempjson=$(jq '.ips += {} | .ips=(.ips|to_entries|map_values(.value.online=false)|from_entries)' arpscan.json)
    if [ $? -ne 0 ]
    then
        echo "Failed to load network JSON" 1>&2
        exit 1
    fi
else
    tempjson={}
fi

jsonescape() {
    jq -Rs . < <(printf "%s" "${1}")
}

starttime="$(jsonescape "$(date '+%Y-%m-%dT%H:%M:%SZ')")"

foundhost() {
    local currentip
    local mac
    currentip="$(jsonescape "${1}")"
    mac="$(jsonescape "${2}")"
    # remove all offline entries for this MAC
    tempjson=$(jq ".ips |= with_entries(if .value.mac==${mac} and .value.online==false then empty else . end)" <<< "${tempjson}")
    # add entry
    tempjson=$(jq "${currentip} as \$ip|.ips[\$ip].mac=${mac}|.ips[\$ip].online=true|.ips[\$ip].lastseen=${starttime}" <<< "${tempjson}")
}

doscan() {
    local nmaplog
    nmaplog=$(sudo nmap -sn -n "${1}")
    if [ $? -ne 0 ]
    then
        echo "nmap failed" 1>&2
        return 1
    fi
    cat <<< "${nmaplog}" > "nmaplog.$(sed 's/\//\./' <<< "${1}").txt"

    local parsestep
    local ipaddr
    parsestep=waitheader
    ipaddr=

    while read -r line
    do
        case $parsestep in
            waitheader)
                if [[ "${line}" != "Starting Nmap "* ]]
                then
                    echo "Nmap start header expected, got ${line}" 1>&2
                    return 1
                fi
                parsestep=hostdata
                ;;
            hostdata)
                if [[ "${line}" == "Nmap done: "* ]]
                then
                    parsestep=scandone
                elif [[ "${line}" =~ ^Nmap\ scan\ report\ for\ (.*)$ ]]
                then
                    ipaddr="${BASH_REMATCH[1]}"
                elif [[ "${line}" =~ ^Host\ is\ up(\ \(.*\))?.$ ]]
                then
                    continue
                elif [[ "${line}" =~ ^MAC\ Address:\ ([A-F0-9:]{17}).*$ ]]
                then
                    local macaddr
                    macaddr="${BASH_REMATCH[1]}"
                    if [[ "${ipaddr}" == "" ]]
                    then
                        echo "Found MAC without IP" 1>&2
                        return 1
                    fi
                    foundhost "${ipaddr}" "${macaddr}"
                    if [ $? -ne 0 ]
                    then
                        echo "Registering host failed" 1>&2
                        return 1
                    fi
                    ipaddr=
                else
                    echo "Failed to parse: ${line}" 1>&2
                    return 1
                fi
                ;;
            scandone)
                echo "Unexpected data after scan: ${line}" 1>&2
                return 1
                ;;
            *)
                echo "Invalid parse step: ${parsestep}" 1>&2
                return 1
                ;;
        esac
    done <<< "$nmaplog"
    #done < nmaplog.txt
}

localifaces="$(ip -j addr | jq '[.[]|{ifname:.ifname,address:.address,addr_info:.addr_info[]}|select(.ifname!="lo")|select(.addr_info.prefixlen>=20)|select(.addr_info.family=="inet")|{ifname:.ifname,ip:.addr_info.local,prefix:.addr_info.prefixlen,mac:(.address|ascii_upcase)}]|map_values(.ip32=(.ip|split(".")|to_entries|map((.value|tonumber)*pow(256;3-.key))|add))|map_values(.subnet32=(.ip32/pow(2;32-.prefix)|floor)*pow(2;32-.prefix))|map_values(.subnet=([(.subnet32/pow(256;3)|floor%256),(.subnet32/pow(256;2)|floor%256),(.subnet32/256|floor%256),.subnet32%256]|join(".")))|map_values(del(.ip32)|del(.subnet32))')"

for i in $(seq "$(jq 'length' <<< "${localifaces}")")
do
    currentiface="$(jq ".[${i}-1]" <<< "${localifaces}")"
    foundhost "$(jq -r '.ip' <<< "${currentiface}")" "$(jq -r '.mac' <<< "${currentiface}")"
    subnet="$(jq -r '.subnet' <<< "${currentiface}")/$(jq '.prefix' <<< "${currentiface}")"
    echo "Scanning ${subnet}"
    doscan "${subnet}"
    if [ $? -ne 0 ]
    then
        echo "Scan failed" 1>&2
        exit 1
    fi
done

# remove old entries
tempjson=$(jq ".ips |= with_entries(if (${starttime}|fromdate)-(.value.lastseen|fromdate)>(14*24*60*60) then empty else . end)" <<< "${tempjson}")

## make sure the MAC vendor and device/port fields exist
#tempjson="$(jq '.macvendor+={}|.devices+=[]' <<< "${tempjson}")"
if [ ! -f macvendor.json ]
then
    echo '{}' > macvendor.json
fi
if [ ! -d devices ]
then
    mkdir -p devices
fi
if [ ! -f devices/_example.json ]
then
    cat <<EOF > devices/_example.json
{
    "desc": "Description of the device",
    "model": "Example Device Model",
    "type": "example",
    "user": "username",
    "ports": [
        {
            "name": "port1",
            "mac": "00:00:00:00:00:00"
        }
    ]
}
EOF
fi

tempjson="$(jq '.ips=(.ips|to_entries|sort_by(.key|split(".")|to_entries|map((.value|tonumber)*pow(256;3-.key))|add)|from_entries)' <<< "${tempjson}")"

fancyjson="$(jq  --slurpfile macvendor macvendor.json --slurpfile devices <(cat devices/*.json) '. as $root|$macvendor[0]|to_entries|map({key:.value[],value:.key})|from_entries as $vendors|($devices|map(.*(.ports[]|with_entries(.key|="port_"+.))))|map_values(del(.ports))|map({key:.port_mac,value:.})|from_entries as $ports|$root.ips|map_values(.port=$ports[.mac]|.vendor=$vendors[.mac[0:8]])' <<< "${tempjson}")"

jq -r '(["[?]","IP","MAC","Vendor","Model","User","Device","Port","Last seen"],(to_entries|sort_by(.key|split(".")|to_entries|map((.value|tonumber)*pow(256;3-.key))|add)|.[]|[if .value.online then "[#]" else "[ ]" end,.key,.value.mac,.value.vendor,.value.port.model,.value.port.user,.value.port.desc,.value.port.port_name,.value.lastseen]))|@tsv' <<< "${fancyjson}" | column -ts $'\t'

cat <<< "${tempjson}" > arpscan.json