Implement peer subscriptions

Incremental updates are passed.
Also implement a server.features RPC

docs/ENVIRONMENT.rst

@@ -89,7 +89,7 @@ These environment variables are optional:
 * **SSL_PORT**
 
   If set ElectrumX will serve SSL clients on **HOST**:**SSL_PORT**.
-  If set SSL_CERTFILE and SSL_KEYFILE must be defined and be
+  If set then SSL_CERTFILE and SSL_KEYFILE must be defined and be
   filesystem paths to those SSL files.
 
 * **RPC_PORT**

server/controller.py

@@ -91,12 +91,10 @@ class Controller(util.LoggedClass):
             ('server',
              'banner donation_address'),
         ]
-        handlers = {'.'.join([prefix, suffix]):
-                    getattr(self, suffix.replace('.', '_'))
-                    for prefix, suffixes in rpcs
-                    for suffix in suffixes.split()}
-        handlers['server.peers.subscribe'] = self.peers.subscribe
-        self.electrumx_handlers = handlers
+        self.electrumx_handlers = {'.'.join([prefix, suffix]):
+                                   getattr(self, suffix.replace('.', '_'))
+                                   for prefix, suffixes in rpcs
+                                   for suffix in suffixes.split()}
 
     async def mempool_transactions(self, hashX):
         '''Generate (hex_hash, tx_fee, unconfirmed) tuples for mempool
@@ -358,6 +356,11 @@ class Controller(util.LoggedClass):
             for session in sessions:
                 await session.notify(self.bp.db_height, touched)
 
+    def notify_peers(self, updates):
+        '''Notify of peer updates.'''
+        for session in self.sessions:
+            session.notify_peers(updates)
+
     def electrum_header(self, height):
         '''Return the binary header at the given height.'''
         if not 0 <= height <= self.bp.db_height:
@@ -605,7 +608,7 @@ class Controller(util.LoggedClass):
 
     def rpc_peers(self):
         '''Return a list of server peers, currently taken from IRC.'''
-        return self.peers.peer_list()
+        return self.peers.peer_dict()
 
     def rpc_reorg(self, count=3):
         '''Force a reorg of the given number of blocks.

server/peers.py

@@ -7,6 +7,8 @@
 
 '''Peer management.'''
 
+import asyncio
+import itertools
 import socket
 from collections import namedtuple
 
@@ -32,20 +34,27 @@ class PeerManager(util.LoggedClass):
         self.env = env
         self.controller = controller
         self.irc = IRC(env, self)
-        self.identities = []
+        self.pruning = None
+        self._identities = []
         # Keyed by nick
         self.irc_peers = {}
+        self.updated_nicks = set()
 
         # We can have a Tor identity inaddition to a normal one
-        self.identities.append(NetIdentity(env.report_host,
-                                           env.report_tcp_port,
-                                           env.report_ssl_port,
-                                           ''))
+        self._identities.append(self.identity(env.report_host,
+                                              env.report_tcp_port,
+                                              env.report_ssl_port,
+                                              ''))
         if env.report_host_tor.endswith('.onion'):
-            self.identities.append(NetIdentity(env.report_host_tor,
-                                               env.report_tcp_port_tor,
-                                               env.report_ssl_port_tor,
-                                               '_tor'))
+            self._identities.append(self.identity(env.report_host_tor,
+                                                  env.report_tcp_port_tor,
+                                                  env.report_ssl_port_tor,
+                                                  '_tor'))
+
+    @classmethod
+    def identity(self, host, tcp_port, ssl_port, suffix):
+        '''Returns a NetIdentity object.  Unpublished ports are None.'''
+        return NetIdentity(host, tcp_port or None, ssl_port or None, suffix)
 
     @classmethod
     def real_name(cls, identity):
@@ -62,19 +71,29 @@ class PeerManager(util.LoggedClass):
         ssl = port_text('s', identity.ssl_port)
         return '{} v{}{}{}'.format(identity.host, cls.VERSION, tcp, ssl)
 
-    def start_irc(self):
-        '''Start up the IRC connections if enabled.'''
+    def identities(self):
+        '''Return a list of network identities of this server.'''
+        return self._identities
+
+    async def refresh_peer_subs(self):
+        for n in itertools.count():
+            await asyncio.sleep(60)
+            updates = [self.irc_peers[nick] for nick in self.updated_nicks
+                       if nick in self.irc_peers]
+            if updates:
+                self.controller.notify_peers(updates)
+            self.updated_nicks.clear()
+
+    async def main_loop(self):
+        '''Not a loop for now...'''
+        self.controller.ensure_future(self.refresh_peer_subs())
         if self.env.irc:
             name_pairs = [(self.real_name(identity), identity.nick_suffix)
-                          for identity in self.identities]
+                          for identity in self._identities]
             self.controller.ensure_future(self.irc.start(name_pairs))
         else:
             self.logger.info('IRC is disabled')
 
-    async def main_loop(self):
-        '''Main loop.  No loop for now.'''
-        self.start_irc()
-
     def dns_lookup_peer(self, nick, hostname, details):
         try:
             ip_addr = None
@@ -83,6 +102,7 @@ class PeerManager(util.LoggedClass):
             except socket.error:
                 pass  # IPv6?
             ip_addr = ip_addr or hostname
+            self.updated_nicks.add(nick)
             self.irc_peers[nick] = IRCPeer(ip_addr, hostname, details)
             self.logger.info('new IRC peer {} at {} ({})'
                              .format(nick, hostname, details))
@@ -102,11 +122,9 @@ class PeerManager(util.LoggedClass):
     def count(self):
         return len(self.irc_peers)
 
-    def peer_list(self):
+    def peer_dict(self):
         return self.irc_peers
 
-    def subscribe(self):
-        '''Returns the server peers as a list of (ip, host, details) tuples.
-
-        Despite the name this is not currently treated as a subscription.'''
+    def peer_list(self):
+        '''Returns the server peers as a list of (ip, host, details) tuples.'''
         return list(self.irc_peers.values())

server/session.py

@@ -7,7 +7,6 @@
 
 '''Classes for local RPC server and remote client TCP/SSL servers.'''
 
-
 import time
 import traceback
 from functools import partial
@@ -105,6 +104,7 @@ class ElectrumX(SessionBase):
         super().__init__(*args, **kwargs)
         self.subscribe_headers = False
         self.subscribe_height = False
+        self.subscribe_peers = False
         self.notified_height = None
         self.max_send = self.env.max_send
         self.max_subs = self.env.max_session_subs
@@ -114,6 +114,8 @@ class ElectrumX(SessionBase):
             'blockchain.headers.subscribe': self.headers_subscribe,
             'blockchain.numblocks.subscribe': self.numblocks_subscribe,
             'blockchain.transaction.broadcast': self.transaction_broadcast,
+            'server.features': self.server_features,
+            'server.peers.subscribe': self.peers_subscribe,
             'server.version': self.server_version,
         }
 
@@ -167,6 +169,23 @@ class ElectrumX(SessionBase):
         self.subscribe_height = True
         return self.height()
 
+    def peers_subscribe(self, incremental=False):
+        '''Returns the server peers as a list of (ip, host, details) tuples.
+
+        If incremental is False there is no subscription.  If True the
+        remote side will receive notifications of new or modified
+        peers (peers that disappeared are not notified).
+        '''
+        self.subscribe_peers = incremental
+        return self.controller.peers.peer_list()
+
+    def notify_peers(self, updates):
+        '''Notify of peer updates.  Updates are sent as a list in the same
+        format as the subscription reply, as the first parameter.
+        '''
+        if self.subscribe_peers:
+            self.send_notification('server.peers.subscribe', [updates])
+
     async def address_subscribe(self, address):
         '''Subscribe to an address.
 
@@ -180,6 +199,20 @@ class ElectrumX(SessionBase):
         self.hashX_subs[hashX] = address
         return status
 
+    def server_features(self):
+        '''Returns a dictionary of server features.'''
+        peers = self.controller.peers
+        hosts = {identity.host: {
+            'tcp_port': identity.tcp_port,
+            'ssl_port': identity.ssl_port,
+            'pruning': peers.pruning,
+            'version': peers.VERSION,
+        } for identity in self.controller.peers.identities()}
+
+        return {
+            'hosts': hosts,
+        }
+
     def server_version(self, client_name=None, protocol_version=None):
         '''Returns the server version as a string.