pi-hole/gravity.sh

#!/usr/bin/env bash
# shellcheck disable=SC1090

# Pi-hole: A black hole for Internet advertisements
# (c) 2017 Pi-hole, LLC (https://pi-hole.net)
# Network-wide ad blocking via your own hardware.
#
# Usage: "pihole -g"
# Compiles a list of ad-serving domains by downloading them from multiple sources
#
# This file is copyright under the latest version of the EUPL.
# Please see LICENSE file for your rights under this license.

export LC_ALL=C

PI_HOLE_SCRIPT_DIR="/opt/pihole"
# Source utils.sh for GetFTLConfigValue
utilsfile="${PI_HOLE_SCRIPT_DIR}/utils.sh"
# shellcheck disable=SC1090
. "${utilsfile}"

coltable="${PI_HOLE_SCRIPT_DIR}/COL_TABLE"
# shellcheck disable=SC1090
. "${coltable}"
# shellcheck disable=SC1091
. "/etc/.pihole/advanced/Scripts/database_migration/gravity-db.sh"

basename="pihole"
PIHOLE_COMMAND="/usr/local/bin/${basename}"

piholeDir="/etc/${basename}"

# Legacy (pre v5.0) list file locations
whitelistFile="${piholeDir}/whitelist.txt"
blacklistFile="${piholeDir}/blacklist.txt"
regexFile="${piholeDir}/regex.list"
adListFile="${piholeDir}/adlists.list"

piholeGitDir="/etc/.pihole"
GRAVITYDB=$(getFTLConfigValue files.gravity)
GRAVITY_TMPDIR=$(getFTLConfigValue files.gravity_tmp)
gravityDBschema="${piholeGitDir}/advanced/Templates/gravity.db.sql"
gravityDBcopy="${piholeGitDir}/advanced/Templates/gravity_copy.sql"

domainsExtension="domains"
curl_connect_timeout=10

# Check gravity temp directory
if [ ! -d "${GRAVITY_TMPDIR}" ] || [ ! -w "${GRAVITY_TMPDIR}" ]; then
  echo -e "  ${COL_LIGHT_RED}Gravity temporary directory does not exist or is not a writeable directory, falling back to /tmp. ${COL_NC}"
  GRAVITY_TMPDIR="/tmp"
fi

# Set this only after sourcing pihole-FTL.conf as the gravity database path may
# have changed
gravityDBfile="${GRAVITYDB}"
gravityDBfile_default="/etc/pihole/gravity.db"
gravityTEMPfile="${GRAVITYDB}_temp"
gravityDIR="$(dirname -- "${gravityDBfile}")"
gravityOLDfile="${gravityDIR}/gravity_old.db"

# Generate new SQLite3 file from schema template
generate_gravity_database() {
  if ! pihole-FTL sqlite3 -ni "${gravityDBfile}" <"${gravityDBschema}"; then
    echo -e "   ${CROSS} Unable to create ${gravityDBfile}"
    return 1
  fi
  chown pihole:pihole "${gravityDBfile}"
  chmod g+w "${piholeDir}" "${gravityDBfile}"
}

# Build gravity tree
gravity_build_tree() {
  local str
  str="Building tree"
  echo -ne "  ${INFO} ${str}..."

  # The index is intentionally not UNIQUE as poor quality adlists may contain domains more than once
  output=$({ pihole-FTL sqlite3 -ni "${gravityTEMPfile}" "CREATE INDEX idx_gravity ON gravity (domain, adlist_id);"; } 2>&1)
  status="$?"

  if [[ "${status}" -ne 0 ]]; then
    echo -e "\\n  ${CROSS} Unable to build gravity tree in ${gravityTEMPfile}\\n  ${output}"
    return 1
  fi
  echo -e "${OVER}  ${TICK} ${str}"
}

# Copy data from old to new database file and swap them
gravity_swap_databases() {
  str="Swapping databases"
  echo -ne "  ${INFO} ${str}..."

  # Swap databases and remove or conditionally rename old database
  # Number of available blocks on disk
  availableBlocks=$(stat -f --format "%a" "${gravityDIR}")
  # Number of blocks, used by gravity.db
  gravityBlocks=$(stat --format "%b" "${gravityDBfile}")
  # Only keep the old database if available disk space is at least twice the size of the existing gravity.db.
  # Better be safe than sorry...
  oldAvail=false
  if [ "${availableBlocks}" -gt "$((gravityBlocks * 2))" ] && [ -f "${gravityDBfile}" ]; then
    oldAvail=true
    mv "${gravityDBfile}" "${gravityOLDfile}"
  else
    rm "${gravityDBfile}"
  fi
  mv "${gravityTEMPfile}" "${gravityDBfile}"
  echo -e "${OVER}  ${TICK} ${str}"

  if $oldAvail; then
    echo -e "  ${TICK} The old database remains available"
  fi
}

# Update timestamp when the gravity table was last updated successfully
update_gravity_timestamp() {
  output=$({ printf ".timeout 30000\\nINSERT OR REPLACE INTO info (property,value) values ('updated',cast(strftime('%%s', 'now') as int));" | pihole-FTL sqlite3 -ni "${gravityTEMPfile}"; } 2>&1)
  status="$?"

  if [[ "${status}" -ne 0 ]]; then
    echo -e "\\n  ${CROSS} Unable to update gravity timestamp in database ${gravityTEMPfile}\\n  ${output}"
    return 1
  fi
  return 0
}

# Import domains from file and store them in the specified database table
database_table_from_file() {
  # Define locals
  local table src backup_path backup_file tmpFile list_type
  table="${1}"
  src="${2}"
  backup_path="${piholeDir}/migration_backup"
  backup_file="${backup_path}/$(basename "${2}")"
  # Create a temporary file. We don't use '--suffix' here because not all
  # implementations of mktemp support it, e.g. on Alpine
  tmpFile="$(mktemp -p "${GRAVITY_TMPDIR}")"
  mv "${tmpFile}" "${tmpFile%.*}.gravity"
  tmpFile="${tmpFile%.*}.gravity"

  local timestamp
  timestamp="$(date --utc +'%s')"

  local rowid
  declare -i rowid
  rowid=1

  # Special handling for domains to be imported into the common domainlist table
  if [[ "${table}" == "whitelist" ]]; then
    list_type="0"
    table="domainlist"
  elif [[ "${table}" == "blacklist" ]]; then
    list_type="1"
    table="domainlist"
  elif [[ "${table}" == "regex" ]]; then
    list_type="3"
    table="domainlist"
  fi

  # Get MAX(id) from domainlist when INSERTing into this table
  if [[ "${table}" == "domainlist" ]]; then
    rowid="$(pihole-FTL sqlite3 -ni "${gravityDBfile}" "SELECT MAX(id) FROM domainlist;")"
    if [[ -z "$rowid" ]]; then
      rowid=0
    fi
    rowid+=1
  fi

  # Loop over all domains in ${src} file
  # Read file line by line
  grep -v '^ *#' <"${src}" | while IFS= read -r domain; do
    # Only add non-empty lines
    if [[ -n "${domain}" ]]; then
      if [[ "${table}" == "domain_audit" ]]; then
        # domain_audit table format (no enable or modified fields)
        echo "${rowid},\"${domain}\",${timestamp}" >>"${tmpFile}"
      elif [[ "${table}" == "adlist" ]]; then
        # Adlist table format
        echo "${rowid},\"${domain}\",1,${timestamp},${timestamp},\"Migrated from ${src}\",,0,0,0,0,0" >>"${tmpFile}"
      else
        # White-, black-, and regexlist table format
        echo "${rowid},${list_type},\"${domain}\",1,${timestamp},${timestamp},\"Migrated from ${src}\"" >>"${tmpFile}"
      fi
      rowid+=1
    fi
  done

  # Store domains in database table specified by ${table}
  # Use printf as .mode and .import need to be on separate lines
  # see https://unix.stackexchange.com/a/445615/83260
  output=$({ printf ".timeout 30000\\n.mode csv\\n.import \"%s\" %s\\n" "${tmpFile}" "${table}" | pihole-FTL sqlite3 -ni "${gravityDBfile}"; } 2>&1)
  status="$?"

  if [[ "${status}" -ne 0 ]]; then
    echo -e "\\n  ${CROSS} Unable to fill table ${table}${list_type} in database ${gravityDBfile}\\n  ${output}"
    gravity_Cleanup "error"
  fi

  # Move source file to backup directory, create directory if not existing
  mkdir -p "${backup_path}"
  mv "${src}" "${backup_file}" 2>/dev/null ||
    echo -e "  ${CROSS} Unable to backup ${src} to ${backup_path}"

  # Delete tmpFile
  rm "${tmpFile}" >/dev/null 2>&1 ||
    echo -e "  ${CROSS} Unable to remove ${tmpFile}"
}

# Check if a column with name ${2} exists in gravity table with name ${1}
gravity_column_exists() {
  output=$({ printf ".timeout 30000\\nSELECT EXISTS(SELECT * FROM pragma_table_info('%s') WHERE name='%s');\\n" "${1}" "${2}" | pihole-FTL sqlite3 -ni "${gravityTEMPfile}"; } 2>&1)
  if [[ "${output}" == "1" ]]; then
    return 0 # Bash 0 is success
  fi

  return 1 # Bash non-0 is failure
}

# Update number of domain on this list. We store this in the "old" database as all values in the new database will later be overwritten
database_adlist_number() {
  # Only try to set number of domains when this field exists in the gravity database
  if ! gravity_column_exists "adlist" "number"; then
    return
  fi

  output=$({ printf ".timeout 30000\\nUPDATE adlist SET number = %i, invalid_domains = %i WHERE id = %i;\\n" "${2}" "${3}" "${1}" | pihole-FTL sqlite3 -ni "${gravityTEMPfile}"; } 2>&1)
  status="$?"

  if [[ "${status}" -ne 0 ]]; then
    echo -e "\\n  ${CROSS} Unable to update number of domains in adlist with ID ${1} in database ${gravityTEMPfile}\\n  ${output}"
    gravity_Cleanup "error"
  fi
}

# Update status of this list. We store this in the "old" database as all values in the new database will later be overwritten
database_adlist_status() {
  # Only try to set the status when this field exists in the gravity database
  if ! gravity_column_exists "adlist" "status"; then
    return
  fi

  output=$({ printf ".timeout 30000\\nUPDATE adlist SET status = %i WHERE id = %i;\\n" "${2}" "${1}" | pihole-FTL sqlite3 -ni "${gravityTEMPfile}"; } 2>&1)
  status="$?"

  if [[ "${status}" -ne 0 ]]; then
    echo -e "\\n  ${CROSS} Unable to update status of adlist with ID ${1} in database ${gravityTEMPfile}\\n  ${output}"
    gravity_Cleanup "error"
  fi
}

# Migrate pre-v5.0 list files to database-based Pi-hole versions
migrate_to_database() {
  # Create database file only if not present
  if [ ! -e "${gravityDBfile}" ]; then
    # Create new database file - note that this will be created in version 1
    echo -e "  ${INFO} Creating new gravity database"
    if ! generate_gravity_database; then
      echo -e "   ${CROSS} Error creating new gravity database. Please contact support."
      return 1
    fi

    # Check if gravity database needs to be updated
    upgrade_gravityDB "${gravityDBfile}" "${piholeDir}"

    # Migrate list files to new database
    if [ -e "${adListFile}" ]; then
      # Store adlist domains in database
      echo -e "  ${INFO} Migrating content of ${adListFile} into new database"
      database_table_from_file "adlist" "${adListFile}"
    fi
    if [ -e "${blacklistFile}" ]; then
      # Store blacklisted domains in database
      echo -e "  ${INFO} Migrating content of ${blacklistFile} into new database"
      database_table_from_file "blacklist" "${blacklistFile}"
    fi
    if [ -e "${whitelistFile}" ]; then
      # Store whitelisted domains in database
      echo -e "  ${INFO} Migrating content of ${whitelistFile} into new database"
      database_table_from_file "whitelist" "${whitelistFile}"
    fi
    if [ -e "${regexFile}" ]; then
      # Store regex domains in database
      # Important note: We need to add the domains to the "regex" table
      # as it will only later be renamed to "regex_blacklist"!
      echo -e "  ${INFO} Migrating content of ${regexFile} into new database"
      database_table_from_file "regex" "${regexFile}"
    fi
  fi

  # Check if gravity database needs to be updated
  upgrade_gravityDB "${gravityDBfile}" "${piholeDir}"
}

# Determine if DNS resolution is available before proceeding
gravity_CheckDNSResolutionAvailable() {
  local lookupDomain="raw.githubusercontent.com"

  # Determine if $lookupDomain is resolvable
  if timeout 4 getent hosts "${lookupDomain}" &>/dev/null; then
    # Print confirmation of resolvability if it had previously failed
    if [[ -n "${secs:-}" ]]; then
      echo -e "${OVER}  ${TICK} DNS resolution is now available\\n"
    fi
    return 0
  elif [[ -n "${secs:-}" ]]; then
    echo -e "${OVER}  ${CROSS} DNS resolution is not available"
    exit 1
  fi

  # If the /etc/resolv.conf contains resolvers other than 127.0.0.1 then the local dnsmasq will not be queried and pi.hole is NXDOMAIN.
  # This means that even though name resolution is working, the getent hosts check fails and the holddown timer keeps ticking and eventually fails
  # So we check the output of the last command and if it failed, attempt to use dig +short as a fallback
  if timeout 4 dig +short "${lookupDomain}" &>/dev/null; then
    if [[ -n "${secs:-}" ]]; then
      echo -e "${OVER}  ${TICK} DNS resolution is now available\\n"
    fi
    return 0
  elif [[ -n "${secs:-}" ]]; then
    echo -e "${OVER}  ${CROSS} DNS resolution is not available"
    exit 1
  fi

  # Determine error output message
  if pgrep pihole-FTL &>/dev/null; then
    echo -e "  ${CROSS} DNS resolution is currently unavailable"
  else
    echo -e "  ${CROSS} DNS service is not running"
    "${PIHOLE_COMMAND}" restartdns
  fi

  # Ensure DNS server is given time to be resolvable
  secs="120"
  echo -ne "  ${INFO} Time until retry: ${secs}"
  until timeout 1 getent hosts "${lookupDomain}" &>/dev/null; do
    [[ "${secs:-}" -eq 0 ]] && break
    echo -ne "${OVER}  ${INFO} Time until retry: ${secs}"
    : $((secs--))
    sleep 1
  done

  # Try again
  gravity_CheckDNSResolutionAvailable
}

# Retrieve blocklist URLs and parse domains from adlist.list
gravity_DownloadBlocklists() {
  echo -e "  ${INFO} ${COL_BOLD}Neutrino emissions detected${COL_NC}..."

  if [[ "${gravityDBfile}" != "${gravityDBfile_default}" ]]; then
    echo -e "  ${INFO} Storing gravity database in ${COL_BOLD}${gravityDBfile}${COL_NC}"
  fi

  # Retrieve source URLs from gravity database
  # We source only enabled adlists, SQLite3 stores boolean values as 0 (false) or 1 (true)
  mapfile -t sources <<<"$(pihole-FTL sqlite3 -ni "${gravityDBfile}" "SELECT address FROM vw_adlist;" 2>/dev/null)"
  mapfile -t sourceIDs <<<"$(pihole-FTL sqlite3 -ni "${gravityDBfile}" "SELECT id FROM vw_adlist;" 2>/dev/null)"
  mapfile -t sourceTypes <<<"$(pihole-FTL sqlite3 -ni "${gravityDBfile}" "SELECT type FROM vw_adlist;" 2>/dev/null)"

  # Parse source domains from $sources
  mapfile -t sourceDomains <<<"$(
    # Logic: Split by folder/port
    awk -F '[/:]' '{
      # Remove URL protocol & optional username:password@
      gsub(/(.*:\/\/|.*:.*@)/, "", $0)
      if(length($1)>0){print $1}
      else {print "local"}
    }' <<<"$(printf '%s\n' "${sources[@]}")" 2>/dev/null
  )"

  local str="Pulling blocklist source list into range"
  echo -e "${OVER}  ${TICK} ${str}"

  if [[ -z "${sources[*]}" ]] || [[ -z "${sourceDomains[*]}" ]]; then
    echo -e "  ${INFO} No source list found, or it is empty"
    echo ""
    unset sources
  fi

  local url domain str target compression adlist_type
  echo ""

  # Prepare new gravity database
  str="Preparing new gravity database"
  echo -ne "  ${INFO} ${str}..."
  rm "${gravityTEMPfile}" >/dev/null 2>&1
  output=$({ pihole-FTL sqlite3 -ni "${gravityTEMPfile}" <"${gravityDBschema}"; } 2>&1)
  status="$?"

  if [[ "${status}" -ne 0 ]]; then
    echo -e "\\n  ${CROSS} Unable to create new database ${gravityTEMPfile}\\n  ${output}"
    gravity_Cleanup "error"
  else
    echo -e "${OVER}  ${TICK} ${str}"
  fi

  str="Creating new gravity databases"
  echo -ne "  ${INFO} ${str}..."

  # Gravity copying SQL script
  copyGravity="$(cat "${gravityDBcopy}")"
  if [[ "${gravityDBfile}" != "${gravityDBfile_default}" ]]; then
    # Replace default gravity script location by custom location
    copyGravity="${copyGravity//"${gravityDBfile_default}"/"${gravityDBfile}"}"
  fi

  output=$({ pihole-FTL sqlite3 -ni "${gravityTEMPfile}" <<<"${copyGravity}"; } 2>&1)
  status="$?"

  if [[ "${status}" -ne 0 ]]; then
    echo -e "\\n  ${CROSS} Unable to copy data from ${gravityDBfile} to ${gravityTEMPfile}\\n  ${output}"
    return 1
  fi
  echo -e "${OVER}  ${TICK} ${str}"

  # Use compression to reduce the amount of data that is transferred
  # between the Pi-hole and the ad list provider. Use this feature
  # only if it is supported by the locally available version of curl
  if curl -V | grep -q "Features:.* libz"; then
    compression="--compressed"
    echo -e "  ${INFO} Using libz compression\n"
  else
    compression=""
    echo -e "  ${INFO} Libz compression not available\n"
  fi
  # Loop through $sources and download each one
  for ((i = 0; i < "${#sources[@]}"; i++)); do
    url="${sources[$i]}"
    domain="${sourceDomains[$i]}"
    id="${sourceIDs[$i]}"
    if [[ "${sourceTypes[$i]}" -eq "0" ]]; then
      # Gravity list
      str="blocklist"
      adlist_type="gravity"
    else
      # AntiGravity list
      str="allowlist"
      adlist_type="antigravity"
    fi

    # Save the file as list.#.domain
    saveLocation="${piholeDir}/list.${id}.${domain}.${domainsExtension}"
    activeDomains[$i]="${saveLocation}"

    echo -e "  ${INFO} Target: ${url}"
    local regex check_url
    # Check for characters NOT allowed in URLs
    regex="[^a-zA-Z0-9:/?&%=~._()-;]"

    # this will remove first @ that is after schema and before domain
    # \1 is optional schema, \2 is userinfo
    check_url="$(sed -re 's#([^:/]*://)?([^/]+)@#\1\2#' <<<"$url")"

    if [[ "${check_url}" =~ ${regex} ]]; then
      echo -e "  ${CROSS} Invalid Target"
    else
      gravity_DownloadBlocklistFromUrl "${url}" "${sourceIDs[$i]}" "${saveLocation}" "${target}" "${compression}" "${adlist_type}" "${domain}"
    fi
    echo ""
  done

  gravity_Blackbody=true
}

compareLists() {
  local adlistID="${1}" target="${2}"

  # Verify checksum when an older checksum exists
  if [[ -s "${target}.sha1" ]]; then
    if ! sha1sum --check --status --strict "${target}.sha1"; then
      # The list changed upstream, we need to update the checksum
      sha1sum "${target}" >"${target}.sha1"
      echo "  ${INFO} List has been updated"
      database_adlist_status "${adlistID}" "1"
    else
      echo "  ${INFO} List stayed unchanged"
      database_adlist_status "${adlistID}" "2"
    fi
  else
    # No checksum available, create one for comparing on the next run
    sha1sum "${target}" >"${target}.sha1"
    # We assume here it was changed upstream
    database_adlist_status "${adlistID}" "1"
  fi
}

# Download specified URL and perform checks on HTTP status and file content
gravity_DownloadBlocklistFromUrl() {
  local url="${1}" adlistID="${2}" saveLocation="${3}" target="${4}" compression="${5}" gravity_type="${6}" domain="${7}"
  local heisenbergCompensator="" listCurlBuffer str httpCode success="" ip cmd_ext
  local file_path permissions ip_addr port blocked=false download=true

  # Create temp file to store content on disk instead of RAM
  # We don't use '--suffix' here because not all implementations of mktemp support it, e.g. on Alpine
  listCurlBuffer="$(mktemp -p "${GRAVITY_TMPDIR}")"
  mv "${listCurlBuffer}" "${listCurlBuffer%.*}.phgpb"
  listCurlBuffer="${listCurlBuffer%.*}.phgpb"

  # Determine if $saveLocation has read permission
  if [[ -r "${saveLocation}" && $url != "file"* ]]; then
    # Have curl determine if a remote file has been modified since last retrieval
    # Uses "Last-Modified" header, which certain web servers do not provide (e.g: raw github urls)
    # Note: Don't do this for local files, always download them
    heisenbergCompensator="-z ${saveLocation}"
  fi

  str="Status:"
  echo -ne "  ${INFO} ${str} Pending..."
  blocked=false
  case $(getFTLConfigValue dns.blocking.mode) in
  "IP-NODATA-AAAA" | "IP")
    # Get IP address of this domain
    ip="$(dig "${domain}" +short)"
    # Check if this IP matches any IP of the system
    if [[ -n "${ip}" && $(grep -Ec "inet(|6) ${ip}" <<<"$(ip a)") -gt 0 ]]; then
      blocked=true
    fi
    ;;
  "NXDOMAIN")
    if [[ $(dig "${domain}" | grep "NXDOMAIN" -c) -ge 1 ]]; then
      blocked=true
    fi
    ;;
  "NODATA")
    if [[ $(dig "${domain}" | grep "NOERROR" -c) -ge 1 ]] && [[ -z $(dig +short "${domain}") ]]; then
      blocked=true
    fi
    ;;
  "NULL" | *)
    if [[ $(dig "${domain}" +short | grep "0.0.0.0" -c) -ge 1 ]]; then
      blocked=true
    fi
    ;;
  esac

  # Check if this domain is blocked by Pi-hole but only if the domain is not a
  # local file or empty
  if [[ $url != "file"* ]] && [[ -n "${domain}" ]]; then
    case $(getFTLConfigValue dns.blocking.mode) in
        "IP-NODATA-AAAA"|"IP")
        # Get IP address of this domain
        ip="$(dig "${domain}" +short)"
        # Check if this IP matches any IP of the system
        if [[ -n "${ip}" && $(grep -Ec "inet(|6) ${ip}" <<< "$(ip a)") -gt 0 ]]; then
            blocked=true
        fi;;
        "NXDOMAIN")
        if [[ $(dig "${domain}" | grep "NXDOMAIN" -c) -ge 1 ]]; then
            blocked=true
        fi;;
        "NODATA")
        if [[ $(dig "${domain}" | grep "NOERROR" -c) -ge 1 ]] && [[ -z $(dig +short "${domain}") ]]; then
            blocked=true
        fi;;
        "NULL"|*)
        if [[ $(dig "${domain}" +short | grep "0.0.0.0" -c) -ge 1 ]]; then
            blocked=true
        fi;;
    esac

    if [[ "${blocked}" == true ]]; then
        # Get first defined upstream server
        local upstream
        upstream="$(getFTLConfigValue dns.upstreams)"

        # Isolate first upstream server from a string like
        # [ 1.2.3.4#1234, 5.6.7.8#5678, ... ]
        upstream="${upstream%%,*}"
        upstream="${upstream##*[}"
        upstream="${upstream%%]*}"
        # Trim leading and trailing spaces and tabs
        upstream="${upstream#"${upstream%%[![:space:]]*}"}"
        upstream="${upstream%"${upstream##*[![:space:]]}"}"

        # Get IP address and port of this upstream server
        local ip_addr port
        printf -v ip_addr "%s" "${upstream%#*}"
        if [[ ${upstream} != *"#"* ]]; then
            port=53
        else
            printf -v port "%s" "${upstream#*#}"
        fi
        ip=$(dig "@${ip_addr}" -p "${port}" +short "${domain}" | tail -1)
        if [[ $(echo "${url}" | awk -F '://' '{print $1}') = "https" ]]; then
            port=443
        else
            port=80
        fi
        echo -e "${OVER}  ${CROSS} ${str} ${domain} is blocked by one of your lists. Using DNS server ${upstream} instead";
        echo -ne "  ${INFO} ${str} Pending..."
        cmd_ext="--resolve $domain:$port:$ip"
    fi
  fi

  # If we are going to "download" a local file, we first check if the target
  # file has a+r permission. We explicitly check for all+read because we want
  # to make sure that the file is readable by everyone and not just the user
  # running the script.
  if [[ $url == "file://"* ]]; then
    # Get the file path
    file_path=$(echo "$url" | cut --delimiter='/' --fields=3-)
    # Check if the file exists and is a regular file (or a symlink to one)
    if [[ ! -e $file_path ]]; then
      # Output that the file does not exist
      echo -e "${OVER}  ${CROSS} ${file_path} does not exist"
      download=false
    elif [[ ! -f $file_path ]]; then
      # Output that the file is not a regular file
      echo -e "${OVER}  ${CROSS} ${file_path} is not a regular file"
      download=false
    else
      # Check if the file has a+r permissions
      permissions=$(stat --dereference --format="%a" "$file_path")
      if [[ $permissions == *4 || $permissions == *5 || $permissions == *6 || $permissions == *7 ]]; then
        # Output that we are using the local file
        echo -e "${OVER}  ${INFO} Using local file ${file_path}"
      else
        # Output that the file does not have the correct permissions
        echo -e "${OVER}  ${CROSS} Cannot read file (file needs to have o+r permission)"
        download=false
      fi
    fi
  fi

  if [[ "${download}" == true ]]; then
    # shellcheck disable=SC2086
    httpCode=$(curl --connect-timeout ${curl_connect_timeout} --silent --location ${compression} ${cmd_ext} ${heisenbergCompensator} --write-out "%{http_code}" "${url}" --output "${listCurlBuffer}" 2>/dev/null)
  fi

  case $url in
  # Did we "download" a local file?
  "file"*)
    if [[ -s "${listCurlBuffer}" ]]; then
      echo -e "${OVER}  ${TICK} ${str} Retrieval successful"
      success=true
    else
      echo -e "${OVER}  ${CROSS} ${str} Retrieval failed / empty list"
    fi
    ;;
  # Did we "download" a remote file?
  *)
    # Determine "Status:" output based on HTTP response
    case "${httpCode}" in
    "200")
      echo -e "${OVER}  ${TICK} ${str} Retrieval successful"
      success=true
      ;;
    "304")
      echo -e "${OVER}  ${TICK} ${str} No changes detected"
      success=true
      ;;
    "000") echo -e "${OVER}  ${CROSS} ${str} Connection Refused" ;;
    "403") echo -e "${OVER}  ${CROSS} ${str} Forbidden" ;;
    "404") echo -e "${OVER}  ${CROSS} ${str} Not found" ;;
    "408") echo -e "${OVER}  ${CROSS} ${str} Time-out" ;;
    "451") echo -e "${OVER}  ${CROSS} ${str} Unavailable For Legal Reasons" ;;
    "500") echo -e "${OVER}  ${CROSS} ${str} Internal Server Error" ;;
    "504") echo -e "${OVER}  ${CROSS} ${str} Connection Timed Out (Gateway)" ;;
    "521") echo -e "${OVER}  ${CROSS} ${str} Web Server Is Down (Cloudflare)" ;;
    "522") echo -e "${OVER}  ${CROSS} ${str} Connection Timed Out (Cloudflare)" ;;
    *) echo -e "${OVER}  ${CROSS} ${str} ${url} (${httpCode})" ;;
    esac
    ;;
  esac

  local done="false"
  # Determine if the blocklist was downloaded and saved correctly
  if [[ "${success}" == true ]]; then
    if [[ "${httpCode}" == "304" ]]; then
      # Add domains to database table file
      pihole-FTL "${gravity_type}" parseList "${saveLocation}" "${gravityTEMPfile}" "${adlistID}"
      database_adlist_status "${adlistID}" "2"
      done="true"
    # Check if $listCurlBuffer is a non-zero length file
    elif [[ -s "${listCurlBuffer}" ]]; then
      # Determine if blocklist is non-standard and parse as appropriate
      gravity_ParseFileIntoDomains "${listCurlBuffer}" "${saveLocation}"
      # Remove curl buffer file after its use
      rm "${listCurlBuffer}"
      # Add domains to database table file
      pihole-FTL "${gravity_type}" parseList "${saveLocation}" "${gravityTEMPfile}" "${adlistID}"
      # Compare lists, are they identical?
      compareLists "${adlistID}" "${saveLocation}"
      done="true"
    else
      # Fall back to previously cached list if $listCurlBuffer is empty
      echo -e "  ${INFO} Received empty file"
    fi
  fi

  # Do we need to fall back to a cached list (if available)?
  if [[ "${done}" != "true" ]]; then
    # Determine if cached list has read permission
    if [[ -r "${saveLocation}" ]]; then
      echo -e "  ${CROSS} List download failed: ${COL_LIGHT_GREEN}using previously cached list${COL_NC}"
      # Add domains to database table file
      pihole-FTL "${gravity_type}" parseList "${saveLocation}" "${gravityTEMPfile}" "${adlistID}"
      database_adlist_status "${adlistID}" "3"
    else
      echo -e "  ${CROSS} List download failed: ${COL_LIGHT_RED}no cached list available${COL_NC}"
      # Manually reset these two numbers because we do not call parseList here
      database_adlist_number "${adlistID}" 0 0
      database_adlist_status "${adlistID}" "4"
    fi
  fi
}

# Parse source files into domains format
gravity_ParseFileIntoDomains() {
  local src="${1}" destination="${2}"

  # Remove comments and print only the domain name
  # Most of the lists downloaded are already in hosts file format but the spacing/formatting is not contiguous
  # This helps with that and makes it easier to read
  # It also helps with debugging so each stage of the script can be researched more in depth
  # 1) Convert all characters to lowercase
  tr '[:upper:]' '[:lower:]' <"${src}" >"${destination}"

  # 2) Remove carriage returns
  # 3) Remove lines starting with ! (ABP Comments)
  # 4) Remove lines starting with [ (ABP Header)
  # 5) Remove lines containing ABP extended CSS selectors ("##", "#!#", "#@#", "#?#") preceded by a letter
  # 6) Remove comments (text starting with "#", include possible spaces before the hash sign)
  # 7) Remove leading tabs, spaces, etc. (Also removes leading IP addresses)
  # 8) Remove empty lines

  sed -i -r \
    -e 's/\r$//' \
    -e 's/\s*!.*//g' \
    -e 's/\s*\[.*//g' \
    -e '/[a-z]\#[$?@]{0,1}\#/d' \
    -e 's/\s*#.*//g' \
    -e 's/^.*\s+//g' \
    -e '/^$/d' "${destination}"

  chmod 644 "${destination}"
}

# Report number of entries in a table
gravity_Table_Count() {
  local table="${1}"
  local str="${2}"
  local num
  num="$(pihole-FTL sqlite3 -ni "${gravityTEMPfile}" "SELECT COUNT(*) FROM ${table};")"
  if [[ "${table}" == "gravity" ]]; then
    local unique
    unique="$(pihole-FTL sqlite3 -ni "${gravityTEMPfile}" "SELECT COUNT(*) FROM (SELECT DISTINCT domain FROM ${table});")"
    echo -e "  ${INFO} Number of ${str}: ${num} (${COL_BOLD}${unique} unique domains${COL_NC})"
    pihole-FTL sqlite3 -ni "${gravityTEMPfile}" "INSERT OR REPLACE INTO info (property,value) VALUES ('gravity_count',${unique});"
  else
    echo -e "  ${INFO} Number of ${str}: ${num}"
  fi
}

# Output count of blacklisted domains and regex filters
gravity_ShowCount() {
  # Here we use the table "gravity" instead of the view "vw_gravity" for speed.
  # It's safe to replace it here, because right after a gravity run both will show the exactly same number of domains.
  gravity_Table_Count "gravity" "gravity domains" ""
  gravity_Table_Count "vw_blacklist" "exact denied domains"
  gravity_Table_Count "vw_regex_blacklist" "regex denied filters"
  gravity_Table_Count "vw_whitelist" "exact allowed domains"
  gravity_Table_Count "vw_regex_whitelist" "regex allowed filters"
}

# Trap Ctrl-C
gravity_Trap() {
  trap '{ echo -e "\\n\\n  ${INFO} ${COL_LIGHT_RED}User-abort detected${COL_NC}"; gravity_Cleanup "error"; }' INT
}

# Clean up after Gravity upon exit or cancellation
gravity_Cleanup() {
  local error="${1:-}"

  str="Cleaning up stray matter"
  echo -ne "  ${INFO} ${str}..."

  # Delete tmp content generated by Gravity
  rm ${piholeDir}/pihole.*.txt 2>/dev/null
  rm ${piholeDir}/*.tmp 2>/dev/null
  # listCurlBuffer location
  rm "${GRAVITY_TMPDIR}"/*.phgpb 2>/dev/null
  # invalid_domains location
  rm "${GRAVITY_TMPDIR}"/*.ph-non-domains 2>/dev/null

  # Ensure this function only runs when gravity_SetDownloadOptions() has completed
  if [[ "${gravity_Blackbody:-}" == true ]]; then
    # Remove any unused .domains files
    for file in "${piholeDir}"/*."${domainsExtension}"; do
      # If list is not in active array, then remove it
      if [[ ! "${activeDomains[*]}" == *"${file}"* ]]; then
        rm -f "${file}" 2>/dev/null ||
          echo -e "  ${CROSS} Failed to remove ${file##*/}"
      fi
    done
  fi

  echo -e "${OVER}  ${TICK} ${str}"

  # # Only restart DNS service if offline
  # if ! pgrep pihole-FTL &> /dev/null; then
  #   "${PIHOLE_COMMAND}" restartdns
  #   dnsWasOffline=true
  # fi

  # Print Pi-hole status if an error occurred
  if [[ -n "${error}" ]]; then
    "${PIHOLE_COMMAND}" status
    exit 1
  fi
}

database_recovery() {
  local result
  local str="Checking integrity of existing gravity database (this can take a while)"
  local option="${1}"
  echo -ne "  ${INFO} ${str}..."
  result="$(pihole-FTL sqlite3 -ni "${gravityDBfile}" "PRAGMA integrity_check" 2>&1)"

  if [[ ${result} = "ok" ]]; then
    echo -e "${OVER}  ${TICK} ${str} - no errors found"

    str="Checking foreign keys of existing gravity database (this can take a while)"
    echo -ne "  ${INFO} ${str}..."
    unset result
    result="$(pihole-FTL sqlite3 -ni "${gravityDBfile}" "PRAGMA foreign_key_check" 2>&1)"
    if [[ -z ${result} ]]; then
      echo -e "${OVER}  ${TICK} ${str} - no errors found"
      if [[ "${option}" != "force" ]]; then
        return
      fi
    else
      echo -e "${OVER}  ${CROSS} ${str} - errors found:"
      while IFS= read -r line; do echo "  - $line"; done <<<"$result"
    fi
  else
    echo -e "${OVER}  ${CROSS} ${str} - errors found:"
    while IFS= read -r line; do echo "  - $line"; done <<<"$result"
  fi

  str="Trying to recover existing gravity database"
  echo -ne "  ${INFO} ${str}..."
  # We have to remove any possibly existing recovery database or this will fail
  rm -f "${gravityDBfile}.recovered" >/dev/null 2>&1
  if result="$(pihole-FTL sqlite3 -ni "${gravityDBfile}" ".recover" | pihole-FTL sqlite3 -ni "${gravityDBfile}.recovered" 2>&1)"; then
    echo -e "${OVER}  ${TICK} ${str} - success"
    mv "${gravityDBfile}" "${gravityDBfile}.old"
    mv "${gravityDBfile}.recovered" "${gravityDBfile}"
    echo -ne " ${INFO} ${gravityDBfile} has been recovered"
    echo -ne " ${INFO} The old ${gravityDBfile} has been moved to ${gravityDBfile}.old"
  else
    echo -e "${OVER}  ${CROSS} ${str} - the following errors happened:"
    while IFS= read -r line; do echo "  - $line"; done <<<"$result"
    echo -e "  ${CROSS} Recovery failed. Try \"pihole -r recreate\" instead."
    exit 1
  fi
  echo ""
}

helpFunc() {
  echo "Usage: pihole -g
Update domains from blocklists specified in adlists.list

Options:
  -f, --force          Force the download of all specified blocklists
  -h, --help           Show this help dialog"
  exit 0
}

repairSelector() {
  case "$1" in
  "recover") recover_database=true ;;
  "recreate") recreate_database=true ;;
  *)
    echo "Usage: pihole -g -r {recover,recreate}
Attempt to repair gravity database

Available options:
  pihole -g -r recover        Try to recover a damaged gravity database file.
                              Pi-hole tries to restore as much as possible
                              from a corrupted gravity database.

  pihole -g -r recover force  Pi-hole will run the recovery process even when
                              no damage is detected. This option is meant to be
                              a last resort. Recovery is a fragile task
                              consuming a lot of resources and shouldn't be
                              performed unnecessarily.

  pihole -g -r recreate       Create a new gravity database file from scratch.
                              This will remove your existing gravity database
                              and create a new file from scratch. If you still
                              have the migration backup created when migrating
                              to Pi-hole v5.0, Pi-hole will import these files."
    exit 0
    ;;
  esac
}

for var in "$@"; do
  case "${var}" in
  "-f" | "--force" ) forceDelete=true;;
  "-r" | "--repair" ) repairSelector "$3";;
  "-u" | "--upgrade" ) upgrade_gravityDB "${gravityDBfile}" "${piholeDir}"; exit 0;;
  "-h" | "--help" ) helpFunc;;
  esac
done

# Remove OLD (backup) gravity file, if it exists
if [[ -f "${gravityOLDfile}" ]]; then
  rm "${gravityOLDfile}"
fi

# Trap Ctrl-C
gravity_Trap

if [[ "${recreate_database:-}" == true ]]; then
  str="Recreating gravity database from migration backup"
  echo -ne "${INFO} ${str}..."
  rm "${gravityDBfile}"
  pushd "${piholeDir}" >/dev/null || exit
  cp migration_backup/* .
  popd >/dev/null || exit
  echo -e "${OVER}  ${TICK} ${str}"
fi

if [[ "${recover_database:-}" == true ]]; then
  database_recovery "$4"
fi

# Move possibly existing legacy files to the gravity database
if ! migrate_to_database; then
  echo -e "   ${CROSS} Unable to migrate to database. Please contact support."
  exit 1
fi

if [[ "${forceDelete:-}" == true ]]; then
  str="Deleting existing list cache"
  echo -ne "${INFO} ${str}..."

  rm /etc/pihole/list.* 2>/dev/null || true
  echo -e "${OVER}  ${TICK} ${str}"
fi

# Gravity downloads blocklists next
if ! gravity_CheckDNSResolutionAvailable; then
  echo -e "   ${CROSS} Can not complete gravity update, no DNS is available. Please contact support."
  exit 1
fi

if ! gravity_DownloadBlocklists; then
  echo -e "   ${CROSS} Unable to create gravity database. Please try again later. If the problem persists, please contact support."
  exit 1
fi

# Update gravity timestamp
update_gravity_timestamp

# Ensure proper permissions are set for the database
chown pihole:pihole "${gravityTEMPfile}"
chmod g+w "${piholeDir}" "${gravityTEMPfile}"

# Build the tree
gravity_build_tree

# Compute numbers to be displayed (do this after building the tree to get the
# numbers quickly from the tree instead of having to scan the whole database)
gravity_ShowCount

# Migrate rest of the data from old to new database
# IMPORTANT: Swapping the databases must be the last step before the cleanup
if ! gravity_swap_databases; then
  echo -e "   ${CROSS} Unable to create database. Please contact support."
  exit 1
fi

gravity_Cleanup
echo ""

echo "  ${TICK} Done."

# "${PIHOLE_COMMAND}" status