Notify xmpp (#2407)

* notify via xmpp (using sendxmpp)

* fix formatting in notify/xmpp.sh

* minor cleanup

notify/xmpp.sh

@@ -0,0 +1,90 @@
+#!/usr/bin/env sh
+
+#Support xmpp via sendxmpp
+
+#XMPP_BIN="/usr/bin/sendxmpp"
+#XMPP_BIN_ARGS="-n -t --tls-ca-path=/etc/ssl/certs"
+#XMPP_TO="zzzz@example.com"
+
+xmpp_send() {
+  _subject="$1"
+  _content="$2"
+  _statusCode="$3" #0: success, 1: error 2($RENEW_SKIP): skipped
+  _debug "_subject" "$_subject"
+  _debug "_content" "$_content"
+  _debug "_statusCode" "$_statusCode"
+
+  XMPP_BIN="${XMPP_BIN:-$(_readaccountconf_mutable XMPP_BIN)}"
+  if [ -n "$XMPP_BIN" ] && ! _exists "$XMPP_BIN"; then
+    _err "It seems that the command $XMPP_BIN is not in path."
+    return 1
+  fi
+  _XMPP_BIN=$(_xmpp_bin)
+  if [ -n "$XMPP_BIN" ]; then
+    _saveaccountconf_mutable XMPP_BIN "$XMPP_BIN"
+  else
+    _clearaccountconf "XMPP_BIN"
+  fi
+
+  XMPP_BIN_ARGS="${XMPP_BIN_ARGS:-$(_readaccountconf_mutable XMPP_BIN_ARGS)}"
+  if [ -n "$XMPP_BIN_ARGS" ]; then
+    _saveaccountconf_mutable XMPP_BIN_ARGS "$XMPP_BIN_ARGS"
+  else
+    _clearaccountconf "XMPP_BIN_ARGS"
+  fi
+
+  XMPP_TO="${XMPP_TO:-$(_readaccountconf_mutable XMPP_TO)}"
+  if [ -n "$XMPP_TO" ]; then
+    if ! _xmpp_valid "$XMPP_TO"; then
+      _err "It seems that the XMPP_TO=$XMPP_TO is not a valid xmpp address."
+      return 1
+    fi
+
+    _saveaccountconf_mutable XMPP_TO "$XMPP_TO"
+  fi
+
+  result=$({ _xmpp_message | eval "$(_xmpp_cmnd)"; } 2>&1)
+
+  # shellcheck disable=SC2181
+  if [ $? -ne 0 ]; then
+    _debug "xmpp send error."
+    _err "$result"
+    return 1
+  fi
+
+  _debug "xmpp send success."
+  return 0
+}
+
+_xmpp_bin() {
+  if [ -n "$XMPP_BIN" ]; then
+    _XMPP_BIN="$XMPP_BIN"
+  elif _exists "sendxmpp"; then
+    _XMPP_BIN="sendxmpp"
+  else
+    _err "Please install sendxmpp first."
+    return 1
+  fi
+
+  echo "$_XMPP_BIN"
+}
+
+_xmpp_cmnd() {
+  case $(basename "$_XMPP_BIN") in
+    sendxmpp)
+      echo "'$_XMPP_BIN' '$XMPP_TO' $XMPP_BIN_ARGS"
+      ;;
+    *)
+      _err "Command $XMPP_BIN is not supported, use sendxmpp."
+      return 1
+      ;;
+  esac
+}
+
+_xmpp_message() {
+  echo "$_subject"
+}
+
+_xmpp_valid() {
+  _contains "$1" "@"
+}