add ssh-et script (see issue MisterTea#291)

scripts/ssh-et

@@ -0,0 +1,119 @@
+#!/usr/bin/env bash
+# Usage:
+# ssh-et [ssh_options] <remote>
+
+# See https://vaneyckt.io/posts/safer_bash_scripts_with_set_euxo_pipefail/
+set -o errexit -o errtrace -o nounset -o pipefail
+
+_command_exists() {
+  command -v -- "$1" &> /dev/null
+}
+
+_log_info() {
+  printf 'ssh-et: %s\n' "$*"
+}
+
+_error() {
+  local error normal
+  # Red color
+  error="$(tput setaf 1 2> /dev/null)" || true
+  normal="$(tput sgr0 2> /dev/null)" || true
+  printf >&2 '%s\n' "${error}${*}${normal}"
+}
+
+_log_error() {
+  _error "$(printf 'ssh-et: %s' "$*")"
+}
+
+_print_usage_and_die() {
+  printf >&2 'Usage: ssh-et [ssh_options] <remote>\n'
+  exit 1
+}
+
+_check_deps() {
+  local s=0
+  if ((BASH_VERSINFO[0] < 4)); then
+    _log_error 'Bash version must be at least 4.0'
+    s=1
+  fi
+  for cmd in et ssh; do
+    if ! _command_exists "${cmd}"; then
+      _log_error "Missing dependency: ${cmd}"
+      s=1
+    fi
+  done
+  return $s
+}
+
+_check_args() {
+  if (($# < 1)); then
+    _print_usage_and_die
+  fi
+  if [[ "${*: -1}" == -* ]]; then
+    _log_error 'Last arg must be a remote, not an SSH option'
+    _print_usage_and_die
+  fi
+}
+
+# The range 49152–65535 contains ephemeral/dynamic ports. We scan 200 ports
+# that start with the prefixes "522" or "622" (the 22 part of the prefix is
+# useful to remember it's used for SSH).
+_find_ephemeral_port() {
+  for port in {52200..52299} {62200..62299}; do
+    # Check if port is open. See: https://stackoverflow.com/a/6943581
+    if ! { printf '' > /dev/tcp/127.0.0.1/"${port}"; } &> /dev/null; then
+      echo "${port}"
+      return 0
+    fi
+  done
+  return 1
+}
+
+main() {
+  _check_deps || return 1
+  _check_args "$@" || return 1
+  local remote="${*: -1}"
+  local ssh_args=("${@:1:(($# - 1))}")
+  local tmpdir
+  tmpdir="$(mktemp -d -t "ssh-et-fifo-$$_XXX")"
+  # NOTE: The path variable in trap must be expanded here because it may not be
+  # defined when the trap is ran.
+  # shellcheck disable=SC2064
+  trap "rm -rf -- '${tmpdir}' &> /dev/null || true" EXIT ERR INT HUP TERM
+  local port
+  if ! port="$(_find_ephemeral_port)"; then
+    _log_error 'Could not find an ephemeral port'
+    return 2
+  fi
+  _log_info "Found open port: ${port}"
+  local et_fifo="${tmpdir}/et_fifo"
+  mkfifo "${et_fifo}" || return $?
+  local et_cmd=(et -t "${port}":22 -N "${remote}")
+  _log_info "Running: ${et_cmd[*]}"
+  "${et_cmd[@]}" > "${et_fifo}" &
+  et_pid=$!
+  found=0
+  while IFS='' read -r line; do
+    printf 'et: %s\n' "${line}"
+    if [[ $line == *"feel free to background"* ]]; then
+      found=1
+      break
+    fi
+  done < "${et_fifo}"
+  ((found)) || return 3
+  # We use the localhost loopback address for all remote hosts, so we don't want
+  # to register it in the known hosts file or do any host auth against it (which
+  # will lead to errors since SSH will think the host key changed). et does its
+  # own host auth so this is hopefully safe.
+  local ssh_cmd=(
+    ssh -o 'UserKnownHostsFile=/dev/null' -o 'StrictHostKeyChecking=no'
+    '127.0.0.1' -p "${port}" "${ssh_args[@]}"
+  )
+  _log_info "Running: ${ssh_cmd[*]}"
+  "${ssh_cmd[@]}"
+  kill "${et_pid}"
+  # wait "${et_pid}"
+  rm -rf -- "${tmpdir}"
+}
+
+main "$@"

src/terminal/TerminalClient.cpp

@@ -220,6 +220,8 @@ void TerminalClient::run(const string& command) {
   TerminalInfo lastTerminalInfo;
 
   if (!console.get()) {
+    // NOTE: ../../scripts/ssh-et relies on the wording of this message, so if
+    // you change it please update it as well.
     CLOG(INFO, "stdout") << "ET running, feel free to background..." << endl;
   }