core/homeassistant/components/webhook/__init__.py

"""Webhooks for Home Assistant."""
from __future__ import annotations

from collections.abc import Awaitable, Callable
from http import HTTPStatus
from ipaddress import ip_address
import logging
import secrets

from aiohttp.web import Request, Response
import voluptuous as vol

from homeassistant.components import websocket_api
from homeassistant.components.http.view import HomeAssistantView
from homeassistant.core import HomeAssistant, callback
from homeassistant.helpers.network import get_url
from homeassistant.helpers.typing import ConfigType
from homeassistant.loader import bind_hass
from homeassistant.util import network
from homeassistant.util.aiohttp import MockRequest, serialize_response

_LOGGER = logging.getLogger(__name__)

DOMAIN = "webhook"

URL_WEBHOOK_PATH = "/api/webhook/{webhook_id}"


@callback
@bind_hass
def async_register(
    hass: HomeAssistant,
    domain: str,
    name: str,
    webhook_id: str,
    handler: Callable[[HomeAssistant, str, Request], Awaitable[Response | None]],
    *,
    local_only=False,
) -> None:
    """Register a webhook."""
    handlers = hass.data.setdefault(DOMAIN, {})

    if webhook_id in handlers:
        raise ValueError("Handler is already defined!")

    handlers[webhook_id] = {
        "domain": domain,
        "name": name,
        "handler": handler,
        "local_only": local_only,
    }


@callback
@bind_hass
def async_unregister(hass: HomeAssistant, webhook_id: str) -> None:
    """Remove a webhook."""
    handlers = hass.data.setdefault(DOMAIN, {})
    handlers.pop(webhook_id, None)


@callback
def async_generate_id() -> str:
    """Generate a webhook_id."""
    return secrets.token_hex(32)


@callback
@bind_hass
def async_generate_url(hass: HomeAssistant, webhook_id: str) -> str:
    """Generate the full URL for a webhook_id."""
    return "{}{}".format(
        get_url(hass, prefer_external=True, allow_cloud=False),
        async_generate_path(webhook_id),
    )


@callback
def async_generate_path(webhook_id: str) -> str:
    """Generate the path component for a webhook_id."""
    return URL_WEBHOOK_PATH.format(webhook_id=webhook_id)


@bind_hass
async def async_handle_webhook(
    hass: HomeAssistant, webhook_id: str, request: Request
) -> Response:
    """Handle a webhook."""
    handlers = hass.data.setdefault(DOMAIN, {})

    # Always respond successfully to not give away if a hook exists or not.
    if (webhook := handlers.get(webhook_id)) is None:
        if isinstance(request, MockRequest):
            received_from = request.mock_source
        else:
            received_from = request.remote

        _LOGGER.warning(
            "Received message for unregistered webhook %s from %s",
            webhook_id,
            received_from,
        )
        # Look at content to provide some context for received webhook
        # Limit to 64 chars to avoid flooding the log
        content = await request.content.read(64)
        _LOGGER.debug("%s", content)
        return Response(status=HTTPStatus.OK)

    if webhook["local_only"]:
        try:
            remote = ip_address(request.remote)
        except ValueError:
            _LOGGER.debug("Unable to parse remote ip %s", request.remote)
            return Response(status=HTTPStatus.OK)

        if not network.is_local(remote):
            _LOGGER.warning("Received remote request for local webhook %s", webhook_id)
            return Response(status=HTTPStatus.OK)

    try:
        response = await webhook["handler"](hass, webhook_id, request)
        if response is None:
            response = Response(status=HTTPStatus.OK)
        return response
    except Exception:  # pylint: disable=broad-except
        _LOGGER.exception("Error processing webhook %s", webhook_id)
        return Response(status=HTTPStatus.OK)


async def async_setup(hass: HomeAssistant, config: ConfigType) -> bool:
    """Initialize the webhook component."""
    hass.http.register_view(WebhookView)
    websocket_api.async_register_command(hass, websocket_list)
    websocket_api.async_register_command(hass, websocket_handle)
    return True


class WebhookView(HomeAssistantView):
    """Handle incoming webhook requests."""

    url = URL_WEBHOOK_PATH
    name = "api:webhook"
    requires_auth = False
    cors_allowed = True

    async def _handle(self, request: Request, webhook_id: str) -> Response:
        """Handle webhook call."""
        # pylint: disable=no-self-use
        _LOGGER.debug("Handling webhook %s payload for %s", request.method, webhook_id)
        hass = request.app["hass"]
        return await async_handle_webhook(hass, webhook_id, request)

    head = _handle
    post = _handle
    put = _handle


@websocket_api.websocket_command(
    {
        "type": "webhook/list",
    }
)
@callback
def websocket_list(hass, connection, msg):
    """Return a list of webhooks."""
    handlers = hass.data.setdefault(DOMAIN, {})
    result = [
        {
            "webhook_id": webhook_id,
            "domain": info["domain"],
            "name": info["name"],
            "local_only": info["local_only"],
        }
        for webhook_id, info in handlers.items()
    ]

    connection.send_message(websocket_api.result_message(msg["id"], result))


@websocket_api.websocket_command(
    {
        vol.Required("type"): "webhook/handle",
        vol.Required("webhook_id"): str,
        vol.Required("method"): vol.In(["GET", "POST", "PUT"]),
        vol.Optional("body", default=""): str,
        vol.Optional("headers", default={}): {str: str},
        vol.Optional("query", default=""): str,
    }
)
@websocket_api.async_response
async def websocket_handle(hass, connection, msg):
    """Handle an incoming webhook via the WS API."""
    request = MockRequest(
        content=msg["body"].encode("utf-8"),
        headers=msg["headers"],
        method=msg["method"],
        query_string=msg["query"],
        mock_source=f"{DOMAIN}/ws",
    )

    response = await async_handle_webhook(hass, msg["webhook_id"], request)

    response_dict = serialize_response(response)
    body = response_dict.get("body")

    connection.send_result(
        msg["id"],
        {
            "body": body,
            "status": response_dict["status"],
            "headers": {"Content-Type": response.content_type},
        },
    )