#!/bin/bash
#
# Purpose : Show the network ports open on this machine: who can reach each one
#           through the firewall, which service opened it and why, and let you
#           stop or start those services.
#
# A service you stop here is also kept from starting at boot, and update leaves
# it off (see enable_services in utils.sh) until you start it here again.

# Wrapped in { ...; exit; } so bash reads the whole script up front; update
# replaces this file while it runs.
{

MINISERVER="$HOME/.local/share/MiniServer"
# Provides firewall_entries and SERVICES_OFF
source "$MINISERVER/utils.sh"

# Why a service or app opens ports, by systemd unit or process name. Services
# with ports here are also listed while they're stopped, so they can be started.
# Format: name|ports|why
KNOWN=(
  "sshd.service|22/tcp|SSH: log in to this machine from other machines"
  "systemd-resolved.service||Looks up domain names (DNS); 5355 is LLMNR, which answers name lookups from the LAN"
  "avahi-daemon.service|5353/udp|mDNS: lets machines on your LAN reach this one as $(uname -n).local"
  "cockpit.socket|9090/tcp|Cockpit: manage this server from a web browser"
  "cockpit.service|9090/tcp|Cockpit: manage this server from a web browser"
  "tailscaled.service|41641/udp|Tailscale: your Core's private network"
  "docker.service||Docker"
  "pm2-$USER.service||pm2: keeps your Node apps running; each app opens its own ports"
  "hermes-gateway.service||The sandbox's proxy for Hermes Agent's gateway (srt); only this machine can reach it"
)

# Stopping these would break the server's network, its firewall or the
# graphical login, so audit doesn't offer to
PROTECTED="systemd-resolved.service NetworkManager.service systemd-networkd.service firewalld.service sddm.service dbus.service dbus-broker.service"

usage() {
  cat << EOF
Usage: audit [--list]

  audit          Show the open ports and choose a service to stop or start
  audit --list   Only show the open ports

Run it with sudo rights: without them, the services run by root can't be named.
EOF
}

known_field() { # <name> <field: 2=ports 3=why>
  local entry
  for entry in "${KNOWN[@]}"; do
    [ "${entry%%|*}" = "$1" ] && { cut -d'|' -f"$2" <<< "$entry"; return 0; }
  done
  return 1
}

# The running known service that uses <proto> <port>, for a socket whose
# process only root can see
known_port_owner() {
  local entry unit
  for entry in "${KNOWN[@]}"; do
    unit="${entry%%|*}"
    [[ ",$(cut -d'|' -f2 <<< "$entry")," == *",$2/$1,"* ]] || continue
    systemctl is-active --quiet "$unit" 2> /dev/null && { echo "system $unit"; return 0; }
  done
  return 1
}

# firewall-cmd, which only answers while firewalld runs
fw() {
  if [ -n "$NO_SUDO" ]; then firewall-cmd "$@"; else sudo firewall-cmd "$@"; fi
}

# The ports a firewalld service opens, as "proto port" lines in
# SERVICE_PORTS[service], with those of the services it includes
declare -A SERVICE_PORTS
cache_service() { # <service>
  [ -n "${SERVICE_PORTS[$1]+set}" ] && return
  # Set first, so services that include each other don't loop
  SERVICE_PORTS[$1]=""
  local info entry inc ports=""
  info="$(fw --info-service="$1" 2> /dev/null)"
  for entry in $(sed -n 's/^ *ports: //p' <<< "$info"); do
    ports+="${entry#*/} ${entry%/*}"$'\n'
  done
  for inc in $(sed -n 's/^ *includes: //p' <<< "$info"); do
    cache_service "$inc"
    ports+="${SERVICE_PORTS[$inc]}"
  done
  SERVICE_PORTS[$1]="$ports"
}

# Add "<level> <proto> <port>" lines to ZONE_RULES[zone] for a service, where
# level is full, or some when only some source addresses are let in
add_service_rules() { # <zone> <level> <service>
  local proto port
  cache_service "$3"
  while read -r proto port; do
    [ -n "$proto" ] && ZONE_RULES[$1]+="$2 $proto $port"$'\n'
  done <<< "${SERVICE_PORTS[$3]}"
}

# What firewalld lets in, from every zone: ZONE_RULES[zone] holds
# "<level> <proto> <port>" lines ("any" for any protocol or port; a port can be
# a range), ZONE_OF_IFACE the zone each interface was put in (others are in
# DEFAULT_ZONE), and SOURCE_ZONES the zones that apply to some source
# addresses on every interface
load_firewall() {
  FIREWALL_ON=0 FIREWALL_UNREAD=0 DEFAULT_ZONE=""
  declare -gA ZONE_RULES ZONE_OF_IFACE
  ZONE_RULES=() ZONE_OF_IFACE=() SOURCE_ZONES=()
  systemctl is-active --quiet firewalld && FIREWALL_ON=1
  [ "$FIREWALL_ON" = 1 ] || return 0

  local all line zone key value level item
  if ! all="$(fw --list-all-zones 2> /dev/null)"; then
    FIREWALL_UNREAD=1
    return 0
  fi
  while IFS= read -r line; do
    # A zone starts unindented, e.g. "public (default, active)"
    if [[ "$line" =~ ^([^[:space:]]+)( \((.*)\))?$ ]]; then
      zone="${BASH_REMATCH[1]}"
      [[ "${BASH_REMATCH[3]}" == *default* ]] && DEFAULT_ZONE="$zone"
      continue
    fi
    [ -n "$zone" ] || continue

    # Rich rules, one per line after "rich rules:". Only those that accept
    # connections count; one limited to a source lets in only some addresses.
    if [[ "$line" =~ ^[[:space:]]+rule[[:space:]] ]]; then
      [[ "$line" =~ [[:space:]]accept([[:space:]]|$) ]] || continue
      level=full
      [[ "$line" == *"source address="* || "$line" == *"source ipset="* || "$line" == *"source mac="* ]] && level=some
      if [[ "$line" =~ [[:space:]]port\ port=\"([0-9-]+)\"\ protocol=\"([a-z]+)\" ]]; then
        ZONE_RULES[$zone]+="$level ${BASH_REMATCH[2]} ${BASH_REMATCH[1]}"$'\n'
      elif [[ "$line" =~ service\ name=\"([^\"]+)\" ]]; then
        add_service_rules "$zone" "$level" "${BASH_REMATCH[1]}"
      else
        ZONE_RULES[$zone]+="$level any any"$'\n'
      fi
      continue
    fi

    [[ "$line" =~ ^[[:space:]]+([a-z -]+):[[:space:]]?(.*)$ ]] || continue
    key="${BASH_REMATCH[1]}" value="${BASH_REMATCH[2]}"
    case "$key" in
      target)
        [ "$value" = ACCEPT ] && ZONE_RULES[$zone]+="full any any"$'\n' ;;
      interfaces)
        for item in $value; do ZONE_OF_IFACE[$item]="$zone"; done ;;
      sources)
        [ -n "$value" ] && SOURCE_ZONES+=("$zone") ;;
      services)
        for item in $value; do add_service_rules "$zone" full "$item"; done ;;
      ports)
        for item in $value; do ZONE_RULES[$zone]+="full ${item#*/} ${item%/*}"$'\n'; done ;;
    esac
  done <<< "$all"
}

# How a zone lets <proto> <port> in: full, some (from some addresses) or ""
zone_allows() { # <zone> <proto> <port>
  local level proto port best=""
  while read -r level proto port; do
    [ -n "$level" ] || continue
    [[ "$proto" == any || "$proto" == "$2" ]] || continue
    [[ "$port" == any ]] || (( $3 >= ${port%-*} && $3 <= ${port#*-} )) || continue
    [ "$level" = full ] && { echo full; return; }
    best=some
  done <<< "${ZONE_RULES[$1]}"
  echo "$best"
}

# How the firewall lets <proto> <port> in from the network of <kind> (lan,
# tailscale or containers): full, some or ""
firewall_allows() { # <proto> <port> <kind>
  local iface level best="" zone
  if [ "$FIREWALL_ON" = 0 ] || [ "$FIREWALL_UNREAD" = 1 ]; then
    [ -n "${IFACES_OF_KIND[$3]}" ] && echo full
    return
  fi
  for iface in ${IFACES_OF_KIND[$3]}; do
    level="$(zone_allows "${ZONE_OF_IFACE[$iface]:-$DEFAULT_ZONE}" "$1" "$2")"
    [ "$level" = full ] && { echo full; return; }
    [ -n "$level" ] && best=some
  done
  # A zone bound to source addresses lets them in on any interface
  if [ -n "${IFACES_OF_KIND[$3]}" ]; then
    for zone in "${SOURCE_ZONES[@]}"; do
      [ -n "$(zone_allows "$zone" "$1" "$2")" ] && best=some
    done
  fi
  echo "$best"
}

# The ports each firewall.conf asks for, as "<proto> <port> <project>" in
# CONF_PORTS, with services expanded to their ports
load_firewall_confs() {
  local conf name entry proto port
  CONF_PORTS=()
  # Only shown alongside the firewall's rules
  [ "$FIREWALL_ON" = 1 ] && [ "$FIREWALL_UNREAD" = 0 ] || return 0
  for conf in "$MINISERVER/firewall.conf" "$HOME/.local/share/siblings/"*/firewall.conf; do
    [ -f "$conf" ] || continue
    name=MiniServer
    [[ "$conf" == */siblings/* ]] && name="$(basename "$(dirname "$conf")")"
    while IFS= read -r entry; do
      case "$entry" in
        port:*)
          entry="${entry#port:}"
          CONF_PORTS+=("${entry#*/} ${entry%/*} $name") ;;
        service:*)
          entry="${entry#service:}"
          cache_service "$entry"
          while read -r proto port; do
            [ -n "$proto" ] && CONF_PORTS+=("$proto $port $name")
          done <<< "${SERVICE_PORTS[$entry]}" ;;
      esac
    done < <(firewall_entries "$conf" 2> /dev/null)
  done
}

# The projects whose firewall.conf asks for <proto> <port>, comma-separated
conf_owners() { # <proto> <port>
  local entry proto port name names=""
  [[ "$2" =~ ^[0-9]+$ ]] || return 0
  for entry in "${CONF_PORTS[@]}"; do
    read -r proto port name <<< "$entry"
    [ "$proto" = "$1" ] || continue
    (( $2 >= ${port%-*} && $2 <= ${port#*-} )) || continue
    [[ ", $names, " == *", $name, "* ]] || names+="${names:+, }$name"
  done
  echo "$names"
}

# Which network an interface is on: local, lan, tailscale or containers
iface_kind() {
  case "$1" in
    lo) echo local ;;
    tailscale*) echo tailscale ;;
    docker*|br-*|veth*|virbr*) echo containers ;;
    *) echo lan ;;
  esac
}

# The systemd unit a process runs in, as "system <unit>", "user <unit>",
# "app <name>" or "none <name>"
process_owner() {
  local pid="$1" comm="$2" cgroup unit
  cgroup="$(cut -d: -f3- "/proc/$pid/cgroup" 2> /dev/null | head -n 1)"
  unit="${cgroup##*/}"
  case "$cgroup" in
    */app-flatpak-*.scope)
      unit="${unit#app-flatpak-}"
      echo "app ${unit%-*.scope}" ;;
    *.scope) echo "app $comm" ;;
    /system.slice/*.service) echo "system $unit" ;;
    /user.slice/*/user@*.service/*.service) echo "user $unit" ;;
    *) echo "none $comm" ;;
  esac
}

# A port systemd itself listens on, for a service it starts on demand
socket_unit() { # <port>
  systemctl list-sockets --all --no-legend 2> /dev/null \
    | awk -v port="$1" '$1 ~ ":" port "$" { print $2; exit }'
}

# Collect the listening sockets into ROWS, one per service and port, with the
# networks each listens on; and the interfaces on each network into
# IFACES_OF_KIND
load_ports() {
  local -A iface_of seen
  local netid local_addr process addr port iface kind pid comm owner key
  ROW_KEYS=()
  declare -gA ROW_PROTO ROW_PORT ROW_OWNER ROW_KINDS IFACES_OF_KIND
  ROW_PROTO=() ROW_PORT=() ROW_OWNER=() ROW_KINDS=() IFACES_OF_KIND=()

  while read -r _ iface _ addr _; do
    iface_of["${addr%/*}"]="$iface"
    kind="$(iface_kind "$iface")"
    [[ " ${IFACES_OF_KIND[$kind]} " == *" $iface "* ]] || IFACES_OF_KIND[$kind]+=" $iface"
  done < <(ip -o addr show 2> /dev/null)

  while read -r netid _ _ _ local_addr _ process; do
    port="${local_addr##*:}"
    addr="${local_addr%:*}"
    addr="${addr#[}" addr="${addr%]}"
    iface=""
    [[ "$addr" == *%* ]] && iface="${addr#*%}" addr="${addr%%%*}"
    case "$addr" in
      0.0.0.0|::|\*) kind=all ;;
      127.*|::1) kind=local ;;
      *) kind="$(iface_kind "${iface:-${iface_of[$addr]:-lan}}")" ;;
    esac

    pid="$(grep -o 'pid=[0-9]*' <<< "$process" | head -n 1 | cut -d= -f2)"
    comm="$(sed -nE 's/^users:\(\("([^"]*)".*/\1/p' <<< "$process")"
    if [ -z "$pid" ]; then
      owner="$(known_port_owner "$netid" "$port")" || owner="none ?"
    elif [ "$comm" = systemd ] && unit="$(socket_unit "$port")" && [ -n "$unit" ]; then
      owner="system $unit"
    elif [ "$comm" = docker-proxy ]; then
      owner="none docker-proxy"
    else
      owner="$(process_owner "$pid" "$comm")"
    fi

    # Random high ports bound to one address are a service's replies and
    # discovery, not something to connect to: one row for all of them
    [[ "$kind" != all && "$port" -ge 32768 ]] && port=random
    key="$netid $port $owner"
    if [ -z "${seen[$key]}" ]; then
      seen[$key]=1
      ROW_KEYS+=("$key")
      ROW_PROTO[$key]="$netid" ROW_PORT[$key]="$port" ROW_OWNER[$key]="$owner"
    fi
    [[ " ${ROW_KINDS[$key]} " == *" $kind "* ]] || ROW_KINDS[$key]+=" $kind"
  done < <($SS -tulpnH 2> /dev/null)
}

# Who can connect to a row's port, given where it listens and the firewall
reach_label() { # <proto> <port> <kinds> <owner>
  local proto="$1" port="$2" kinds="$3" lan=0 ts=0 ct=0 blocked=0 parts=()
  [ "$port" = random ] && port=0
  for kind in $kinds; do
    case "$kind" in
      all) lan=1 ts=1 ;;
      lan) lan=1 ;;
      tailscale) ts=1 ;;
      containers) ct=1 ;;
    esac
  done
  if [ "$lan" = 1 ]; then
    # Docker opens the ports containers publish itself, ahead of firewalld
    if [ "$4" = "none docker-proxy" ]; then
      parts+=("\e[31mLAN\e[0m (past the firewall)")
    else
      case "$(firewall_allows "$proto" "$port" lan)" in
        full) parts+=("\e[31mLAN\e[0m") ;;
        some) parts+=("\e[31mLAN\e[0m (some addresses)") ;;
        *) blocked=1 ;;
      esac
    fi
  fi
  if [ "$ts" = 1 ] && [ -n "$(firewall_allows "$proto" "$port" tailscale)" ]; then
    parts+=("\e[33mTailscale\e[0m")
  fi
  if [ "$ct" = 1 ] && [ -n "$(firewall_allows "$proto" "$port" containers)" ]; then
    parts+=("\e[33mcontainers\e[0m")
  fi
  [ ${#parts[@]} -eq 0 ] && parts=("\e[32mthis machine\e[0m")
  local label="${parts[0]}" part
  for part in "${parts[@]:1}"; do label+=", $part"; done
  [ "$blocked" = 1 ] && label+=" (firewall blocks LAN)"
  echo -n "$label"
}

owner_label() {
  local scope="${1%% *}" name="${1#* }"
  case "$scope" in
    system) echo "${name%.service}" ;;
    user) echo "${name%.service} (yours)" ;;
    app) echo "$name (app)" ;;
    *) [ "$name" = docker-proxy ] && echo "Docker container" || echo "$name" ;;
  esac
}

why() {
  local scope="${1%% *}" name="${1#* }" text
  text="$(known_field "$name" 3)" && { echo "$text"; return; }
  case "$scope" in
    system) systemctl show -p Description --value "$name" 2> /dev/null ;;
    user) systemctl --user show -p Description --value "$name" 2> /dev/null ;;
    none)
      case "$name" in
        "?") echo "Run audit with sudo rights to see which service this is" ;;
        docker-proxy) echo "A port a Docker container publishes; see: docker ps" ;;
      esac ;;
  esac
}

# For a port other machines on the LAN can reach: which firewall.conf asks for
# it, or a warning that none does. Containers' ports needn't be listed.
conf_note() { # <proto> <port> <owner>
  local owners
  [ "$3" = "none docker-proxy" ] && return
  owners="$(conf_owners "$1" "$2")"
  if [ -n "$owners" ]; then
    echo -n " [firewall.conf: $owners]"
  else
    echo -n " \e[31m[in no firewall.conf]\e[0m"
  fi
}

systemctl_for() { # <scope> <arguments>
  if [ "$1" = user ]; then systemctl --user "${@:2}"; else sudo systemctl "${@:2}"; fi
}

is_active() { # <scope> <unit>
  if [ "$1" = user ]; then systemctl --user is-active --quiet "$2"; else systemctl is-active --quiet "$2"; fi
}

# Services that can be stopped or started here, as "scope unit": those with
# open ports, then the known ones that are installed
load_services() {
  local key owner entry unit
  SERVICES_LIST=()
  for key in "${ROW_KEYS[@]}"; do
    owner="${ROW_OWNER[$key]}"
    [[ "$owner" == system\ * || "$owner" == user\ * ]] || continue
    [[ " $PROTECTED " == *" ${owner#* } "* ]] && continue
    [[ " ${SERVICES_LIST[*]} " == *" $owner "* ]] || SERVICES_LIST+=("$owner")
  done
  for entry in "${KNOWN[@]}"; do
    unit="${entry%%|*}"
    [[ "$unit" == *.service || "$unit" == *.socket ]] || continue
    [ -n "$(known_field "$unit" 2)" ] || continue
    [[ " ${SERVICES_LIST[*]} " == *" system $unit "* ]] && continue
    # Listed even while running without its port open yet, as right after
    # starting, so it doesn't seem to vanish
    systemctl cat "$unit" &> /dev/null || continue
    # cockpit.socket and cockpit.service are one service to the user
    [[ "$unit" == *.socket && " ${SERVICES_LIST[*]} " == *" system ${unit%.socket}.service "* ]] && continue
    [[ "$unit" == *.service && " ${SERVICES_LIST[*]} " == *" system ${unit%.service}.socket "* ]] && continue
    SERVICES_LIST+=("system $unit")
  done
}

show_ports() {
  local key reach note text
  echo
  if [ "$FIREWALL_ON" = 0 ]; then
    echo -e "\e[31mFirewall (firewalld) off: every port listening beyond this machine can be reached.\e[0m"
  elif [ "$FIREWALL_UNREAD" = 1 ]; then
    echo -e "\e[33mFirewall (firewalld) on, but its rules couldn't be read: ports are shown as if it let everything in.\e[0m"
  else
    echo "Firewall (firewalld) on: it blocks connections from other machines except to the ports its zones allow."
    echo "Ports the LAN can reach show which firewall.conf asks for them (MiniServer's or a sibling project's)."
  fi
  [ -n "$NO_SUDO" ] && echo "Without sudo rights, the services run by root show as \"?\"."
  echo
  printf "\e[1m%-7s %-5s %-34s %-26s %s\e[0m\n" PORT PROTO "OPEN TO" SERVICE WHY
  local sorted visible
  # By port, with the random ports last
  mapfile -t sorted < <(for key in "${ROW_KEYS[@]}"; do
      printf '%s\t%s\n' "${ROW_PORT[$key]/random/99999}" "$key"; done | sort -n -k1,1 | cut -f2-)
  for key in "${sorted[@]}"; do
    reach="$(reach_label "${ROW_PROTO[$key]}" "${ROW_PORT[$key]}" "${ROW_KINDS[$key]}" "${ROW_OWNER[$key]}")"
    # printf counts the color codes as width, so pad by the visible length
    visible="$(sed 's/\\e\[[0-9;]*m//g' <<< "$reach")"
    note=""
    if [[ "$visible" == *LAN* && "$visible" != *"blocks LAN"* && "$FIREWALL_ON" = 1 && "$FIREWALL_UNREAD" = 0 ]]; then
      note="$(conf_note "${ROW_PROTO[$key]}" "${ROW_PORT[$key]}" "${ROW_OWNER[$key]}")"
    fi
    text="$(why "${ROW_OWNER[$key]}")"
    [ -z "$text" ] && note="${note# }"
    printf "%-7s %-5s %b%*s %-26s %s%b\n" "${ROW_PORT[$key]}" "${ROW_PROTO[$key]}" \
      "$reach" $((34 - ${#visible})) "" "$(owner_label "${ROW_OWNER[$key]}")" "$text" "$note"
  done
}

show_services() {
  local i scope unit state
  echo
  echo "Services you can stop or start:"
  echo
  for i in "${!SERVICES_LIST[@]}"; do
    scope="${SERVICES_LIST[$i]%% *}" unit="${SERVICES_LIST[$i]#* }"
    if is_active "$scope" "$unit"; then state="\e[32mrunning\e[0m"; else state="\e[33mstopped\e[0m"; fi
    printf "  %2d) %-30b %b\n" $((i + 1)) "$(owner_label "${SERVICES_LIST[$i]}")" "$state"
  done
}

toggle() { # <scope> <unit>
  local scope="$1" unit="$2" units=("$2") pair
  if [[ " $PROTECTED " == *" $unit "* ]]; then
    echo "$unit keeps the server or its network working, so audit won't stop it."
    return 1
  fi
  if [ "$unit" = sshd.service ] && [ -n "$SSH_CONNECTION" ] && is_active "$scope" "$unit"; then
    echo "You're logged in over SSH: stopping sshd would lock you out."
    return 1
  fi
  # A service started on demand has a socket unit too; both go together
  case "$unit" in
    *.socket) pair="${unit%.socket}.service" ;;
    *.service) pair="${unit%.service}.socket" ;;
  esac
  systemctl_for "$scope" cat "$pair" &> /dev/null && units+=("$pair")

  mkdir -p "$(dirname "$SERVICES_OFF")"
  if is_active "$scope" "$unit"; then
    confirm "Stop ${units[*]} and keep it from starting at boot?" || return 0
    systemctl_for "$scope" disable --now "${units[@]}" || return 1
    for unit in "${units[@]}"; do
      grep -qsx "$scope $unit" "$SERVICES_OFF" || echo "$scope $unit" >> "$SERVICES_OFF"
    done
  else
    confirm "Start ${units[*]} and start it at boot?" || return 0
    systemctl_for "$scope" enable --now "${units[@]}" || return 1
    for unit in "${units[@]}"; do
      sed -i "\|^$scope $unit\$|d" "$SERVICES_OFF" 2> /dev/null
    done
    wait_for_ports "$2"
  fi
}

# A service takes a moment to open its ports once started: wait up to 10
# seconds for its known ones, so the table shows them
wait_for_ports() { # <unit>
  local ports port proto
  ports="$(known_field "$1" 2)" || return 0
  for port in ${ports//,/ }; do
    proto="${port#*/}" port="${port%/*}"
    echo "Waiting for $1 to open port $port..."
    for _ in $(seq 40); do
      [ -n "$(ss -lnH "--$proto" "sport = :$port" 2> /dev/null)" ] && break
      sleep 0.25
    done
  done
}

confirm() {
  local answer
  read -rp "$1 [y/N] " answer
  [[ "$answer" == [yY]* ]]
}

case "$1" in
  ""|-l|--list) ;;
  -h|--help) usage; exit 0 ;;
  *) usage; exit 2 ;;
esac

# Root's sockets name their process only to root
SS="sudo ss"
NO_SUDO=""
if ! sudo -v; then
  SS="ss"
  NO_SUDO=1
fi

while true; do
  load_firewall
  load_firewall_confs
  load_ports
  show_ports
  [ -n "$1" ] && exit 0

  load_services
  show_services
  echo
  echo "   q) Quit"
  echo
  while true; do
    read -rp "Choose a service to stop or start: " choice || exit 0
    case "$choice" in
      q|Q|"") exit 0 ;;
      *[!0-9]*) ;;
      *)
        if (( choice >= 1 && choice <= ${#SERVICES_LIST[@]} )); then
          entry="${SERVICES_LIST[$((choice - 1))]}"
          toggle "${entry%% *}" "${entry#* }"
          break
        fi ;;
    esac
    echo "Choose a number from the list, or q."
  done
done
}