relay/actor.py

   1 import aiohttp
   2 import aiohttp.web
   3 import asyncio
   4 import logging
   5 import uuid
   6 import re
   7 import simplejson as json
   8 import cgi
   9 from urllib.parse import urlsplit
  10 from Crypto.PublicKey import RSA
  11 from .database import DATABASE
  12 from .http_debug import http_debug
  13
  14 from cachetools import LFUCache
  15
  16
  17 # generate actor keys if not present
  18 if "actorKeys" not in DATABASE:
  19     logging.info("No actor keys present, generating 4096-bit RSA keypair.")
  20
  21     privkey = RSA.generate(4096)
  22     pubkey = privkey.publickey()
  23
  24     DATABASE["actorKeys"] = {
  25         "publicKey": pubkey.exportKey('PEM').decode('utf-8'),
  26         "privateKey": privkey.exportKey('PEM').decode('utf-8')
  27     }
  28
  29
  30 PRIVKEY = RSA.importKey(DATABASE["actorKeys"]["privateKey"])
  31 PUBKEY = PRIVKEY.publickey()
  32
  33
  34 from . import app, CONFIG
  35 from .remote_actor import fetch_actor
  36
  37
  38 AP_CONFIG = CONFIG.get('ap', {'host': 'localhost','blocked_instances':[], 'whitelist_enabled': False, 'whitelist': []})
  39 CACHE_SIZE = CONFIG.get('cache-size', 16384)
  40
  41
  42 CACHE = LFUCache(CACHE_SIZE)
  43
  44
  45 async def actor(request):
  46     data = {
  47         "@context": "https://www.w3.org/ns/activitystreams",
  48         "endpoints": {
  49             "sharedInbox": "https://{}/inbox".format(request.host)
  50         },
  51         "followers": "https://{}/followers".format(request.host),
  52         "following": "https://{}/following".format(request.host),
  53         "inbox": "https://{}/inbox".format(request.host),
  54         "name": "ActivityRelay",
  55         "type": "Application",
  56         "id": "https://{}/actor".format(request.host),
  57         "publicKey": {
  58             "id": "https://{}/actor#main-key".format(request.host),
  59             "owner": "https://{}/actor".format(request.host),
  60             "publicKeyPem": DATABASE["actorKeys"]["publicKey"]
  61         },
  62         "summary": "ActivityRelay bot",
  63         "preferredUsername": "relay",
  64         "url": "https://{}/actor".format(request.host)
  65     }
  66     return aiohttp.web.json_response(data)
  67
  68
  69 app.router.add_get('/actor', actor)
  70
  71
  72 from .http_signatures import sign_headers
  73
  74
  75 get_actor_inbox = lambda actor: actor.get('endpoints', {}).get('sharedInbox', actor['inbox'])
  76
  77
  78 async def push_message_to_actor(actor, message, our_key_id):
  79     inbox = get_actor_inbox(actor)
  80
  81     url = urlsplit(inbox)
  82
  83     # XXX: Digest
  84     data = json.dumps(message)
  85     headers = {
  86         '(request-target)': 'post {}'.format(url.path),
  87         'Content-Length': str(len(data)),
  88         'Content-Type': 'application/activity+json',
  89         'User-Agent': 'ActivityRelay'
  90     }
  91     headers['signature'] = sign_headers(headers, PRIVKEY, our_key_id)
  92     headers.pop('(request-target)')
  93
  94     logging.debug('%r >> %r', inbox, message)
  95
  96     try:
  97         async with aiohttp.ClientSession(trace_configs=[http_debug()]) as session:
  98             async with session.post(inbox, data=data, headers=headers) as resp:
  99                 if resp.status == 202:
 100                     return
 101                 resp_payload = await resp.text()
 102                 logging.debug('%r >> resp %r', inbox, resp_payload)
 103     except Exception as e:
 104         logging.info('Caught %r while pushing to %r.', e, inbox)
 105
 106
 107 async def follow_remote_actor(actor_uri):
 108     actor = await fetch_actor(actor_uri)
 109
 110     if not actor:
 111         logging.info('failed to fetch actor at: %r', actor_uri)
 112         return
 113
 114     if AP_CONFIG['whitelist_enabled'] is True and urlsplit(actor_uri).hostname not in AP_CONFIG['whitelist']:
 115         logging.info('refusing to follow non-whitelisted actor: %r', actor_uri)
 116         return
 117
 118     logging.info('following: %r', actor_uri)
 119
 120     message = {
 121         "@context": "https://www.w3.org/ns/activitystreams",
 122         "type": "Follow",
 123         "to": [actor['id']],
 124         "object": actor['id'],
 125         "id": "https://{}/activities/{}".format(AP_CONFIG['host'], uuid.uuid4()),
 126         "actor": "https://{}/actor".format(AP_CONFIG['host'])
 127     }
 128     await push_message_to_actor(actor, message, "https://{}/actor#main-key".format(AP_CONFIG['host']))
 129
 130
 131 async def unfollow_remote_actor(actor_uri):
 132     actor = await fetch_actor(actor_uri)
 133     if not actor:
 134         logging.info('failed to fetch actor at: %r', actor_uri)
 135         return
 136
 137     logging.info('unfollowing: %r', actor_uri)
 138
 139     message = {
 140         "@context": "https://www.w3.org/ns/activitystreams",
 141         "type": "Undo",
 142         "to": [actor['id']],
 143         "object": {
 144              "type": "Follow",
 145              "object": actor_uri,
 146              "actor": actor['id'],
 147              "id": "https://{}/activities/{}".format(AP_CONFIG['host'], uuid.uuid4())
 148         },
 149         "id": "https://{}/activities/{}".format(AP_CONFIG['host'], uuid.uuid4()),
 150         "actor": "https://{}/actor".format(AP_CONFIG['host'])
 151     }
 152     await push_message_to_actor(actor, message, "https://{}/actor#main-key".format(AP_CONFIG['host']))
 153
 154
 155 tag_re = re.compile(r'(<!--.*?-->|<[^>]*>)')
 156 def strip_html(data):
 157     no_tags = tag_re.sub('', data)
 158     return cgi.escape(no_tags)
 159
 160
 161 def distill_inboxes(actor, object_id):
 162     global DATABASE
 163
 164     origin_hostname = urlsplit(object_id).hostname
 165
 166     inbox = get_actor_inbox(actor)
 167     targets = [target for target in DATABASE.get('relay-list', []) if target != inbox]
 168     targets = [target for target in targets if urlsplit(target).hostname != origin_hostname]
 169     hostnames = [urlsplit(target).hostname for target in targets]
 170
 171     assert inbox not in targets
 172     assert origin_hostname not in hostnames
 173
 174     return targets
 175
 176
 177 def distill_object_id(activity):
 178     logging.debug('>> determining object ID for %r', activity['object'])
 179     obj = activity['object']
 180
 181     if isinstance(obj, str):
 182         return obj
 183
 184     return obj['id']
 185
 186
 187 async def handle_relay(actor, data, request):
 188     global CACHE
 189
 190     object_id = distill_object_id(data)
 191
 192     if object_id in CACHE:
 193         logging.debug('>> already relayed %r as %r', object_id, CACHE[object_id])
 194         return
 195
 196     activity_id = "https://{}/activities/{}".format(request.host, uuid.uuid4())
 197
 198     message = {
 199         "@context": "https://www.w3.org/ns/activitystreams",
 200         "type": "Announce",
 201         "to": ["https://{}/followers".format(request.host)],
 202         "actor": "https://{}/actor".format(request.host),
 203         "object": object_id,
 204         "id": activity_id
 205     }
 206
 207     logging.debug('>> relay: %r', message)
 208
 209     inboxes = distill_inboxes(actor, object_id)
 210
 211     futures = [push_message_to_actor({'inbox': inbox}, message, 'https://{}/actor#main-key'.format(request.host)) for inbox in inboxes]
 212     asyncio.ensure_future(asyncio.gather(*futures))
 213
 214     CACHE[object_id] = activity_id
 215
 216
 217 async def handle_forward(actor, data, request):
 218     object_id = distill_object_id(data)
 219
 220     logging.debug('>> Relay %r', data)
 221
 222     inboxes = distill_inboxes(actor, object_id)
 223
 224     futures = [
 225         push_message_to_actor(
 226             {'inbox': inbox},
 227             data,
 228             'https://{}/actor#main-key'.format(request.host))
 229         for inbox in inboxes]
 230     asyncio.ensure_future(asyncio.gather(*futures))
 231
 232
 233 async def handle_follow(actor, data, request):
 234     global DATABASE
 235
 236     following = DATABASE.get('relay-list', [])
 237     inbox = get_actor_inbox(actor)
 238
 239     if urlsplit(inbox).hostname in AP_CONFIG['blocked_instances']:
 240         return
 241
 242     if inbox not in following:
 243         following += [inbox]
 244         DATABASE['relay-list'] = following
 245
 246         if data['object'].endswith('/actor'):
 247             asyncio.ensure_future(follow_remote_actor(actor['id']))
 248
 249     message = {
 250         "@context": "https://www.w3.org/ns/activitystreams",
 251         "type": "Accept",
 252         "to": [actor["id"]],
 253         "actor": "https://{}/actor".format(request.host),
 254
 255         # this is wrong per litepub, but mastodon < 2.4 is not compliant with that profile.
 256         "object": {
 257              "type": "Follow",
 258              "id": data["id"],
 259              "object": "https://{}/actor".format(request.host),
 260              "actor": actor["id"]
 261         },
 262
 263         "id": "https://{}/activities/{}".format(request.host, uuid.uuid4()),
 264     }
 265
 266     asyncio.ensure_future(push_message_to_actor(actor, message, 'https://{}/actor#main-key'.format(request.host)))
 267
 268
 269 async def handle_undo(actor, data, request):
 270     global DATABASE
 271
 272     child = data['object']
 273     if child['type'] == 'Follow':
 274         following = DATABASE.get('relay-list', [])
 275
 276         inbox = get_actor_inbox(actor)
 277
 278         if inbox in following:
 279             following.remove(inbox)
 280             DATABASE['relay-list'] = following
 281
 282         if child['object'].endswith('/actor'):
 283             await unfollow_remote_actor(actor['id'])
 284
 285
 286 processors = {
 287     'Announce': handle_relay,
 288     'Create': handle_relay,
 289     'Delete': handle_forward,
 290     'Follow': handle_follow,
 291     'Undo': handle_undo,
 292     'Update': handle_forward,
 293 }
 294
 295
 296 async def inbox(request):
 297     data = await request.json()
 298     instance = urlsplit(data['actor']).hostname
 299
 300     if 'actor' not in data or not request['validated']:
 301         raise aiohttp.web.HTTPUnauthorized(body='access denied', content_type='text/plain')
 302
 303     elif data['type'] != 'Follow' and 'https://{}/inbox'.format(instance) not in DATABASE['relay-list']:
 304         raise aiohttp.web.HTTPUnauthorized(body='access denied', content_type='text/plain')
 305
 306     elif AP_CONFIG['whitelist_enabled'] is True and instance not in AP_CONFIG['whitelist']:
 307         raise aiohttp.web.HTTPUnauthorized(body='access denied', content_type='text/plain')
 308
 309     actor = await fetch_actor(data["actor"])
 310     actor_uri = 'https://{}/actor'.format(request.host)
 311
 312     logging.debug(">> payload %r", data)
 313
 314     processor = processors.get(data['type'], None)
 315     if processor:
 316         await processor(actor, data, request)
 317
 318     return aiohttp.web.Response(body=b'{}', content_type='application/activity+json')
 319
 320
 321 app.router.add_post('/inbox', inbox)