#!/bin/bash
#
# Installs device manager on the local machine.
#
# Specifically:
#
# 1. Fetches the binaries required for a device manager installation from a few
# possible sources.
#
# 2. Sets up the helper with setuid.  The helper binary needs to be owned by
# root and have the suid bit set, to enable the device manager to run binaries
# under different system accounts than itself.
#
# 3. Runs the self-install command on the device manager.
#
# Usage:
#
# # Gets binaries from local repository
# ./dminstall <install parent dir>
#
# # Gets binaries from local filesystem
# ./dminstall <install parent dir> /path/to/binaries
#
# # Gets binaries from HTTP server
# ./dminstall <install parent dir> http://host/path

set -e

usage() {
  echo "usage:"
  echo "./dminstall [--single_user] <install parent dir> [<binary source>] [-- args for device manager...]"
}

readonly BIN_NAMES=(deviced suidhelper agentd)

###############################################################################
# Copies one binary from source to destination.
# Arguments:
#   name of the binary
#   source dir of binary
#   destination dir of binary
# Returns:
#   None
###############################################################################
copy_binary() {
  local -r BIN_NAME="$1"
  local -r BIN_SRC_DIR="$2"
  local -r BIN_DEST_DIR="$3"
  local -r SOURCE="${BIN_SRC_DIR}/${BIN_NAME}"
  if [[ -x "${SOURCE}" ]]; then
    local -r DESTINATION="${BIN_DEST_DIR}/${BIN_NAME}"
    cp "${SOURCE}" "${DESTINATION}"
    chmod 700 "${DESTINATION}"
  else
    echo "couldn't find ${SOURCE}"
    exit 1
  fi
}

###############################################################################
# Fetches binaries needed by device manager installation.
# Globals:
#   BIN_NAMES
#   VEYRON_ROOT
# Arguments:
#   destination for binaries
#   source of binaries
# Returns:
#   None
###############################################################################
get_binaries() {
  local -r BIN_INSTALL="$1"
  local -r BIN_SOURCE="$2"

  local bin_names_str=""
  for bin_name in "${BIN_NAMES[@]}"; do
    bin_names_str+=" ${bin_name}"
  done

  # If source is not specified, try to look for it in the repository.
  if [[ -z "${BIN_SOURCE}" ]]; then
    if [[ -z "${VEYRON_ROOT}" ]]; then
      echo 'ERROR: binary source not specified and no local repository available'
      exit 1
    fi
    local -r REPO_BIN_DIR="${VEYRON_ROOT}/veyron/go/bin"
    echo "Fetching binaries:${bin_names_str} from build repository: ${REPO_BIN_DIR} ..."
    for bin_name in "${BIN_NAMES[@]}"; do
      copy_binary "${bin_name}" "${REPO_BIN_DIR}" "${BIN_INSTALL}"
    done
    return
  fi

  # If the source is specified as an existing local filesystem path,
  # look for the binaries there.
  if [[ -d "${BIN_SOURCE}" ]]; then
      echo "Fetching binaries:${bin_names_str} locally from: ${BIN_SOURCE} ..."
      for bin_name in "${BIN_NAMES[@]}"; do
        copy_binary "${bin_name}" "${BIN_SOURCE}" "${BIN_INSTALL}"
      done
      return
  fi

  # If the source looks like a URL, use HTTP to fetch.
  local -r URL_REGEXP='^(https?|ftp|file)://'
  if [[ "${BIN_SOURCE}" =~ ${URL_REGEXP} ]]; then
    echo "Fetching binaries:${bin_names_str} remotely from: ${BIN_SOURCE} ..."
      for bin_name in "${BIN_NAMES[@]}"; do
        local DEST="${BIN_INSTALL}/${bin_name}"
        curl -f -o "${DEST}" "${BIN_SOURCE}/${bin_name}"
        chmod 700 "${DEST}"
      done
      return
  fi

  echo 'ERROR: couldn'"'"'t fetch binaries.'
  exit 1
}

main() {
  if [[ "$1" == "--single_user" ]]; then
    local -r SINGLE_USER=true
    shift
    local -r AGENT_FLAG="--no_passphrase"
  else
    local -r SINGLE_USER=false
    local -r AGENT_FLAG=""
  fi
  local -r INSTALL_PARENT_DIR="$1"
  if [[ -z "${INSTALL_PARENT_DIR}" ]]; then
    echo 'No local install destination specified!'
    usage
    exit 1
  fi
  shift

  if [[ ! -d "${INSTALL_PARENT_DIR}" ]]; then
    echo "${INSTALL_PARENT_DIR} is not a directory!"
    exit 1
  fi

  local -r INSTALL_DIR="${INSTALL_PARENT_DIR}/device_manager"

  # TODO(caprita): Check that the device manager is not already installed before
  # proceeding.  We should require an explicit uninstall to avoid wiping away
  # the device manager accidentally.
  if [[ ${SINGLE_USER} == false ]]; then
    sudo rm -rf "${INSTALL_DIR}"
  else
    rm -rf "${INSTALL_DIR}"
  fi
  mkdir -m 700 "${INSTALL_DIR}"

  local -r BIN_INSTALL="${INSTALL_DIR}/bin"
  mkdir -m 700 "${BIN_INSTALL}"

  # Fetch the binaries.
  if [[ $# = 0 || "$1" = "--" ]]; then
    local -r BIN_SOURCE=""
  else
    local -r BIN_SOURCE="$1"
    shift
  fi
  get_binaries "${BIN_INSTALL}" "${BIN_SOURCE}"
  for bin_name in "${BIN_NAMES[@]}"; do
    local BINARY="${BIN_INSTALL}/${bin_name}"
    if [[ ! -s "${BINARY}" ]]; then
      echo "${BINARY} is empty."
      exit 1
    fi
  done
  echo "Binaries are in ${BIN_INSTALL}."

  # Set up the suidhelper.
  echo "Configuring suidhelper ..."
  local -r SETUID_SCRIPT="${BIN_INSTALL}/suidhelper"
  if [[ ${SINGLE_USER} == false ]]; then
    sudo bash -c "chown root:root \"${SETUID_SCRIPT}\"; chmod 4551 \"${SETUID_SCRIPT}\""
  fi
  echo "Suidhelper configured."

  # Tell the device manager to install itself.
  local -r DM_ROOT="${INSTALL_DIR}/dmroot"
  echo "Installing device manager under ${DM_ROOT} ..."
  local -r PUBLISH=$(hostname)
  if [[ "$1" = "--" ]]; then
    shift
  elif [[ $# != 0 ]]; then
    echo "Unexpected arguments: $@"
    usage
    exit 1
  fi

  VEYRON_DM_CURRENT="${INSTALL_DIR}/deviced.curr" VEYRON_DM_ROOT="${DM_ROOT}" VEYRON_DM_HELPER="${SETUID_SCRIPT}" "${BIN_INSTALL}/deviced" --install_self -- --name="${PUBLISH}" "$@"
  echo "Device manager installed."

  local -r SECURITY_DIR="${INSTALL_DIR}/security"
  mkdir -m 700 "${SECURITY_DIR}"
  local -r PRINCIPAL_DIR="${SECURITY_DIR}/principal"
  mkdir -m 700 "${PRINCIPAL_DIR}"
  local -r AGENT_KEY_DIR="${SECURITY_DIR}/keys"
  mkdir -m 700 "${AGENT_KEY_DIR}"

  # Run device manager under the security agent.
  echo
  echo "Running:"
  echo "VEYRON_CREDENTIALS=\"${PRINCIPAL_DIR}\" \"${BIN_INSTALL}/agentd\" ${AGENT_FLAG} --additional_principals=\"${AGENT_KEY_DIR}\" \"${INSTALL_DIR}/deviced.curr\""
  echo
  # NOTE: If you update the command below, please also update the command echoed
  # above to keep the two in sync.
  VEYRON_CREDENTIALS="${PRINCIPAL_DIR}" exec "${BIN_INSTALL}/agentd" ${AGENT_FLAG} --additional_principals="${AGENT_KEY_DIR}" "${INSTALL_DIR}/deviced.curr"
}

main "$@"