MailSend/scripts/prepare-dovecot.sh

#!/usr/bin/env bash
set -euo pipefail

project_dir="${MAILHUB_PROJECT_DIR:-$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd -P)}"
data_dir="${MAILHUB_DATA_DIR:-${project_dir}/data}"

fail() {
  echo "Dovecot preparation failed: $*" >&2
  exit 1
}

command -v openssl >/dev/null 2>&1 || fail "openssl is required."
[[ ! -L "${data_dir}" ]] || fail "data directory must not be a symbolic link."
mkdir -p "${data_dir}"
data_dir="$(cd "${data_dir}" && pwd -P)"
secret_file="${MAILHUB_DOVECOT_SECRET_FILE:-${data_dir}/secrets/dovecot_auth_secret}"
webmail_secret_file="${MAILHUB_WEBMAIL_SSO_SECRET_FILE:-${data_dir}/secrets/webmail_sso_secret}"
maildir_root="${MAILHUB_MAILDIR_ROOT:-${data_dir}/maildir}"
host_os="$(uname -s)"
host_uid="$(id -u)"
webmail_reader_gid="${MAILHUB_WEBMAIL_SSO_READER_GID:-}"

if [[ -z "${webmail_reader_gid}" && -f "${project_dir}/.env" ]]; then
  webmail_reader_gid_count="$(awk -F= '
    $1 == "WEBMAIL_SSO_READER_GID" { count++ }
    END { print count + 0 }
  ' "${project_dir}/.env")"
  (( webmail_reader_gid_count <= 1 )) \
    || fail "WEBMAIL_SSO_READER_GID must appear at most once in .env."
  webmail_reader_gid="$(awk -F= '
    $1 == "WEBMAIL_SSO_READER_GID" { value = substr($0, index($0, "=") + 1) }
    END { print value }
  ' "${project_dir}/.env")"
  webmail_reader_gid="${webmail_reader_gid%$'\r'}"
fi
webmail_reader_gid="${webmail_reader_gid:-1000}"
[[ "${webmail_reader_gid}" =~ ^[0-9]+$ ]] \
  || fail "Webmail SSO reader gid must be a positive numeric gid."
webmail_reader_gid="$((10#${webmail_reader_gid}))"
(( webmail_reader_gid > 0 && webmail_reader_gid <= 2147483647 )) \
  || fail "Webmail SSO reader gid must be a positive numeric gid."

if [[ "${host_os}" == "Linux" && "${host_uid}" != "0" && "${host_uid}" != "1000" ]]; then
  fail "Linux preparation must run as root or host uid 1000 so the rootless containers can read and write their bind mounts."
fi

case "${secret_file}" in
  "${data_dir}"/*) ;;
  *) fail "secret file must stay inside the MailHub data directory." ;;
esac
case "${webmail_secret_file}" in
  "${data_dir}"/*) ;;
  *) fail "Webmail SSO secret file must stay inside the MailHub data directory." ;;
esac
case "${maildir_root}" in
  "${data_dir}"/*) ;;
  *) fail "Maildir root must stay inside the MailHub data directory." ;;
esac

[[ ! -L "${secret_file}" ]] || fail "secret file must not be a symbolic link."
[[ ! -L "${webmail_secret_file}" ]] || fail "Webmail SSO secret file must not be a symbolic link."
[[ ! -L "${maildir_root}" ]] || fail "Maildir root must not be a symbolic link."
mkdir -p "$(dirname "${secret_file}")" "$(dirname "${webmail_secret_file}")" "${maildir_root}"
secret_dir="$(dirname "${secret_file}")"
webmail_secret_dir="$(dirname "${webmail_secret_file}")"

prepare_secret() {
  local file="$1"
  local prefix="$2"
  local temporary_secret
  if [[ ! -f "${file}" ]]; then
    umask 077
    temporary_secret="$(mktemp "$(dirname "${file}")/.${prefix}.XXXXXX")"
    if ! openssl rand -hex 32 >"${temporary_secret}"; then
      rm -f -- "${temporary_secret}"
      fail "unable to generate ${prefix} secret."
    fi
    chmod 0600 "${temporary_secret}"
    mv "${temporary_secret}" "${file}"
  fi
  [[ -f "${file}" ]] || fail "${prefix} secret path must be a regular file."
  local value
  value="$(tr -d '\r\n' <"${file}")"
  [[ "${value}" =~ ^[0-9a-fA-F]+$ ]] || fail "${prefix} secret must contain only hexadecimal characters."
  (( ${#value} >= 64 && ${#value} <= 512 )) || fail "${prefix} secret must contain 64-512 hexadecimal characters."
}

prepare_secret "${secret_file}" "dovecot-auth"
prepare_secret "${webmail_secret_file}" "webmail-sso"

if [[ "${host_uid}" == "0" ]]; then
  chown 1000:1000 \
    "${secret_dir}" \
    "${secret_file}" \
    "${maildir_root}"
  # MailHub remains the owner. The dedicated reader group allows the actual
  # Roundcube PHP worker gid to read the shared secret without world access.
  chown "1000:${webmail_reader_gid}" \
    "${webmail_secret_dir}" \
    "${webmail_secret_file}"
fi
chmod 0700 "${maildir_root}"
chmod 0750 "${secret_dir}" "${webmail_secret_dir}"
chmod 0400 "${secret_file}"
chmod 0440 "${webmail_secret_file}"
if [[ "${host_os}" == "Linux" ]]; then
  [[ "$(stat -c '%g' "${webmail_secret_dir}")" == "${webmail_reader_gid}" \
    && "$(stat -c '%g' "${webmail_secret_file}")" == "${webmail_reader_gid}" ]] \
    || fail "Webmail SSO secret reader gid could not be applied; run preparation as root."
fi

echo "Dovecot storage and authentication secrets are ready."