Add DuckDNS component (#9556)

* Add DuckDNS component

* Address comments

homeassistant/components/duckdns.py

@@ -0,0 +1,102 @@
+"""Integrate with DuckDNS."""
+import asyncio
+from datetime import timedelta
+import logging
+
+import voluptuous as vol
+
+from homeassistant.const import CONF_ACCESS_TOKEN, CONF_DOMAIN
+from homeassistant.loader import bind_hass
+import homeassistant.helpers.config_validation as cv
+from homeassistant.helpers.event import async_track_time_interval
+from homeassistant.helpers.aiohttp_client import async_get_clientsession
+
+DOMAIN = 'duckdns'
+UPDATE_URL = 'https://www.duckdns.org/update'
+INTERVAL = timedelta(minutes=5)
+_LOGGER = logging.getLogger(__name__)
+SERVICE_SET_TXT = 'set_txt'
+ATTR_TXT = 'txt'
+
+CONFIG_SCHEMA = vol.Schema({
+    DOMAIN: vol.Schema({
+        vol.Required(CONF_DOMAIN): cv.string,
+        vol.Required(CONF_ACCESS_TOKEN): cv.string,
+    })
+}, extra=vol.ALLOW_EXTRA)
+
+SERVICE_TXT_SCHEMA = vol.Schema({
+    vol.Required(ATTR_TXT): vol.Any(None, cv.string)
+})
+
+
+@bind_hass
+@asyncio.coroutine
+def async_set_txt(hass, txt):
+    """Set the txt record. Pass in None to remove it."""
+    yield from hass.services.async_call(DOMAIN, SERVICE_SET_TXT, {
+        ATTR_TXT: txt
+    }, blocking=True)
+
+
+@asyncio.coroutine
+def async_setup(hass, config):
+    """Initialize the DuckDNS component."""
+    domain = config[DOMAIN][CONF_DOMAIN]
+    token = config[DOMAIN][CONF_ACCESS_TOKEN]
+    session = async_get_clientsession(hass)
+
+    result = yield from _update_duckdns(session, domain, token)
+
+    if not result:
+        return False
+
+    @asyncio.coroutine
+    def update_domain_interval(now):
+        """Update the DuckDNS entry."""
+        yield from _update_duckdns(session, domain, token)
+
+    @asyncio.coroutine
+    def update_domain_service(call):
+        """Update the DuckDNS entry."""
+        yield from _update_duckdns(session, domain, token,
+                                   txt=call.data[ATTR_TXT])
+
+    async_track_time_interval(hass, update_domain_interval, INTERVAL)
+    hass.services.async_register(
+        DOMAIN, SERVICE_SET_TXT, update_domain_service,
+        schema=SERVICE_TXT_SCHEMA)
+
+    return result
+
+
+_SENTINEL = object()
+
+
+@asyncio.coroutine
+def _update_duckdns(session, domain, token, *, txt=_SENTINEL, clear=False):
+    """Update DuckDNS."""
+    params = {
+        'domains': domain,
+        'token': token,
+    }
+
+    if txt is not _SENTINEL:
+        if txt is None:
+            # Pass in empty txt value to indicate it's clearing txt record
+            params['txt'] = ''
+            clear = True
+        else:
+            params['txt'] = txt
+
+    if clear:
+        params['clear'] = 'true'
+
+    resp = yield from session.get(UPDATE_URL, params=params)
+    body = yield from resp.text()
+
+    if body != 'OK':
+        _LOGGER.warning('Updating DuckDNS domain %s failed', domain)
+        return False
+
+    return True