New feature: force peer discovery via proxy

Set FORCE_PROXY to non-empty to force peer discovery to go
through the proxy.  See docs/ENVIRONMENT.rst

Wait for an attempt at proxy discovery to be made before beginning
peer discovery.

docs/ENVIRONMENT.rst

@@ -251,6 +251,15 @@ some of this.
   peer discovery if it notices it is not present in the peer's
   returned list.
 
+* **FORCE_PROXY**
+
+  By default peer discovery happens over the clear internet.  Set this
+  to non-empty to force peer discovery to be done via the proxy.  This
+  might be useful if you are running a Tor service exclusively and
+  wish to keep your IP address private.  **NOTE**: in such a case you
+  should leave **IRC** unset as IRC connections are *always* over the
+  normal internet.
+
 * **TOR_PROXY_HOST**
 
   The host where your Tor proxy is running.  Defaults to *localhost*.
@@ -316,7 +325,8 @@ connectivity on IRC:
 
 * **IRC**
 
-  Set to anything non-empty to advertise on IRC
+  Set to anything non-empty to advertise on IRC.  ElectrumX connects
+  to IRC over the clear internet, always.
 
 * **IRC_NICK**
 

lib/socks.py

@@ -146,6 +146,7 @@ class SocksProxy(util.LoggedClass):
         self.errors = 0
         self.ip_addr = None
         self.lost_event = asyncio.Event()
+        self.tried_event = asyncio.Event()
         self.loop = loop or asyncio.get_event_loop()
         self.set_lost()
 
@@ -209,6 +210,8 @@ class SocksProxy(util.LoggedClass):
                     self.logger.info('failed to detect proxy at {}: {}'
                                      .format(util.address_string(paddress), e))
 
+        self.tried_event.set()
+
         # Failed all ports?
         if sock is None:
             return

server/env.py

@@ -53,6 +53,7 @@ class Env(LoggedClass):
         # Peer discovery
         self.peer_discovery = bool(self.default('PEER_DISCOVERY', True))
         self.peer_announce = bool(self.default('PEER_ANNOUNCE', True))
+        self.force_proxy = bool(self.default('FORCE_PROXY', False))
         self.tor_proxy_host = self.default('TOR_PROXY_HOST', 'localhost')
         self.tor_proxy_port = self.integer('TOR_PROXY_PORT', None)
         # The electrum client takes the empty string as unspecified

server/peers.py

@@ -195,15 +195,7 @@ class PeerSession(JSONSession):
     def shutdown_connection(self):
         self.peer.last_connect = time.time()
         is_good = not (self.failed or self.bad)
-        self.peer_mgr.set_connection_status(self.peer, is_good)
-        if self.peer.is_tor:
-            how = 'via {} over Tor'.format(self.kind)
-        else:
-            how = 'via {} at {}'.format(self.kind,
-                                        self.peer_addr(anon=False))
-        status = 'verified' if is_good else 'failed to verify'
-        elapsed = time.time() - self.peer.last_try
-        self.log_info('{} {} in {:.1f}s'.format(status, how, elapsed))
+        self.peer_mgr.set_verification_status(self.peer, self.kind, is_good)
         self.close_connection()
 
 
@@ -230,8 +222,8 @@ class PeerManager(util.LoggedClass):
         self.peers = set()
         self.onion_peers = []
         self.permit_onion_peer_time = time.time()
-        self.tor_proxy = SocksProxy(env.tor_proxy_host, env.tor_proxy_port,
-                                    loop=self.loop)
+        self.proxy = SocksProxy(env.tor_proxy_host, env.tor_proxy_port,
+                                loop=self.loop)
         self.import_peers()
 
     def my_clearnet_peer(self):
@@ -462,13 +454,19 @@ class PeerManager(util.LoggedClass):
           2) Verifying connectivity of new peers.
           3) Retrying old peers at regular intervals.
         '''
-        self.ensure_future(self.tor_proxy.auto_detect_loop())
         self.connect_to_irc()
         if not self.env.peer_discovery:
             self.logger.info('peer discovery is disabled')
             return
 
+        # Wait a few seconds after starting the proxy detection loop
+        # for proxy detection to succeed
+        self.ensure_future(self.proxy.auto_detect_loop())
+        await self.proxy.tried_event.wait()
+
         self.logger.info('beginning peer discovery')
+        self.logger.info('force use of proxy: {}'.format(self.env.force_proxy))
+
         try:
             while True:
                 timeout = self.loop.call_later(WAKEUP_SECS,
@@ -516,11 +514,11 @@ class PeerManager(util.LoggedClass):
         kind, port = port_pairs[0]
         sslc = ssl.SSLContext(ssl.PROTOCOL_TLS) if kind == 'SSL' else None
 
-        if peer.is_tor:
-            # Don't attempt an onion connection if we don't have a tor proxy
-            if not self.tor_proxy.is_up():
+        if self.env.force_proxy or peer.is_tor:
+            # Only attempt a proxy connection if the proxy is up
+            if not self.proxy.is_up():
                 return
-            create_connection = self.tor_proxy.create_connection
+            create_connection = self.proxy.create_connection
         else:
             create_connection = self.loop.create_connection
 
@@ -546,10 +544,18 @@ class PeerManager(util.LoggedClass):
             if port_pairs:
                 self.retry_peer(peer, port_pairs)
             else:
-                self.set_connection_status(peer, False)
+                self.maybe_forget_peer(peer)
+
+    def set_verification_status(self, peer, kind, good):
+        '''Called when a verification succeeded or failed.'''
+        if self.env.force_proxy or peer.is_tor:
+            how = 'via {} over Tor'.format(kind)
+        else:
+            how = 'via {} at {}'.format(kind, peer.ip_addr)
+        status = 'verified' if good else 'failed to verify'
+        elapsed = time.time() - peer.last_try
+        self.log_info('{} {} in {:.1f}s'.format(status, how, elapsed))
 
-    def set_connection_status(self, peer, good):
-        '''Called when a connection succeeded or failed.'''
         if good:
             peer.try_count = 0
             peer.source = 'peer'

server/session.py

@@ -277,9 +277,9 @@ class ElectrumX(SessionBase):
     def is_tor(self):
         '''Try to detect if the connection is to a tor hidden service we are
         running.'''
-        tor_proxy = self.controller.peer_mgr.tor_proxy
+        proxy = self.controller.peer_mgr.proxy
         peer_info = self.peer_info()
-        return peer_info and peer_info[0] == tor_proxy.ip_addr
+        return peer_info and peer_info[0] == proxy.ip_addr
 
     async def replaced_banner(self, banner):
         network_info = await self.controller.daemon_request('getnetworkinfo')