URI: 
       tUse select. - electrum - Electrum Bitcoin wallet
  HTML git clone https://git.parazyd.org/electrum
   DIR Log
   DIR Files
   DIR Refs
   DIR Submodules
       ---
   DIR commit 49a48d52ac3c6f364bbf57f0b88f969acad4cf3b
   DIR parent aedfbd3855cd1e24ab9e4c76b20413a95ac39912
  HTML Author: Neil Booth <kyuupichan@gmail.com>
       Date:   Wed,  3 Jun 2015 00:03:33 +0900
       
       Use select.
       
       Diffstat:
         M lib/interface.py                    |     344 +++++++++++++++----------------
         M lib/network.py                      |     297 +++++++++++++++++++------------
       
       2 files changed, 348 insertions(+), 293 deletions(-)
       ---
   DIR diff --git a/lib/interface.py b/lib/interface.py
       t@@ -17,10 +17,14 @@
        # along with this program. If not, see <http://www.gnu.org/licenses/>.
        
        
       -import copy, re, errno, os
       -import threading, traceback, sys, time, Queue
       +import os
       +import re
        import socket
        import ssl
       +import sys
       +import threading
       +import time
       +import traceback
        
        import requests
        ca_path = requests.certs.where()
       t@@ -28,49 +32,30 @@ ca_path = requests.certs.where()
        import util
        import x509
        import pem
       -from version import ELECTRUM_VERSION, PROTOCOL_VERSION
       -from simple_config import SimpleConfig
        
        
       -def Interface(server, response_queue, config = None):
       -    """Interface factory function.  The returned interface class handles the connection
       -    to a single remote electrum server.  The object handles all necessary locking.  It's
       -    exposed API is:
       +def Connection(server, queue, config_path):
       +    """Makes asynchronous connections to a remote remote electrum server.
       +    Returns the running thread that is making the connection.
        
       -    - Inherits everything from threading.Thread.
       -    - Member functions send_request(), stop(), is_connected()
       -    - Member variable server.
       -    
       -    "server" is constant for the object's lifetime and hence synchronization is unnecessary.
       +    Once the thread has connected, it finishes, placing a tuple on the
       +    queue of the form (server, socket), where socket is None if
       +    connection failed.
            """
            host, port, protocol = server.split(':')
       -    if protocol in 'st':
       -        return TcpInterface(server, response_queue, config)
       -    else:
       -        raise Exception('Unknown protocol: %s'%protocol)
       -
       -# Connection status
       -CS_OPENING, CS_CONNECTED, CS_FAILED = range(3)
       +    if not protocol in 'st':
       +        raise Exception('Unknown protocol: %s' % protocol)
       +    c = TcpConnection(server, queue, config_path)
       +    c.start()
       +    return c
        
       -class TcpInterface(threading.Thread):
       +class TcpConnection(threading.Thread):
        
       -    def __init__(self, server, response_queue, config = None):
       +    def __init__(self, server, queue, config_path):
                threading.Thread.__init__(self)
                self.daemon = True
       -        self.config = config if config is not None else SimpleConfig()
       -        # Set by stop(); no more data is exchanged and the thread exits after gracefully
       -        # closing the socket
       -        self.disconnect = False
       -        self._status = CS_OPENING
       -        self.debug = False # dump network messages. can be changed at runtime using the console
       -        self.message_id = 0
       -        self.response_queue = response_queue
       -        self.request_queue = Queue.Queue()
       -        self.unanswered_requests = {}
       -        # request timeouts
       -        self.request_time = time.time()
       -        self.ping_time = 0
       -        # parse server
       +        self.config_path = config_path
       +        self.queue = queue
                self.server = server
                self.host, self.port, self.protocol = self.server.split(':')
                self.host = str(self.host)
       t@@ -78,47 +63,31 @@ class TcpInterface(threading.Thread):
                self.use_ssl = (self.protocol == 's')
        
            def print_error(self, *msg):
       -        util.print_error("[%s]"%self.host, *msg)
       -
       -    def process_response(self, response):
       -        if self.debug:
       -            self.print_error("<--", response)
       -
       -        msg_id = response.get('id')
       -        error = response.get('error')
       -        result = response.get('result')
       -
       -        if msg_id is not None:
       -            method, params, _id, queue = self.unanswered_requests.pop(msg_id)
       -            if queue is None:
       -                queue = self.response_queue
       +        util.print_error("[%s]" % self.host, *msg)
       +
       +    def check_host_name(self, peercert, name):
       +        """Simple certificate/host name checker.  Returns True if the
       +        certificate matches, False otherwise.  Does not support
       +        wildcards."""
       +        # Check that the peer has supplied a certificate.
       +        # None/{} is not acceptable.
       +        if not peercert:
       +            return False
       +        if peercert.has_key("subjectAltName"):
       +            for typ, val in peercert["subjectAltName"]:
       +                if typ == "DNS" and val == name:
       +                    return True
                else:
       -            # notification
       -            method = response.get('method')
       -            params = response.get('params')
       -            _id = None
       -            queue = self.response_queue
       -            # restore parameters
       -            if method == 'blockchain.numblocks.subscribe':
       -                result = params[0]
       -                params = []
       -            elif method == 'blockchain.headers.subscribe':
       -                result = params[0]
       -                params = []
       -            elif method == 'blockchain.address.subscribe':
       -                addr = params[0]
       -                result = params[1]
       -                params = [addr]
       -
       -        if method == 'server.version':
       -            self.server_version = result
       -            return
       -
       -        if error:
       -            queue.put((self, {'method':method, 'params':params, 'error':error, 'id':_id}))
       -        else:
       -            queue.put((self, {'method':method, 'params':params, 'result':result, 'id':_id}))
       -
       +            # Only check the subject DN if there is no subject alternative
       +            # name.
       +            cn = None
       +            for attr, val in peercert["subject"]:
       +                # Use most-specific (last) commonName attribute.
       +                if attr == "commonName":
       +                    cn = val
       +            if cn is not None:
       +                return cn == name
       +        return False
        
            def get_simple_socket(self):
                try:
       t@@ -138,10 +107,9 @@ class TcpInterface(threading.Thread):
                else:
                    self.print_error("failed to connect", str(e))
        
       -
            def get_socket(self):
                if self.use_ssl:
       -            cert_path = os.path.join( self.config.path, 'certs', self.host)
       +            cert_path = os.path.join(self.config_path, 'certs', self.host)
                    if not os.path.exists(cert_path):
                        is_new = True
                        s = self.get_simple_socket()
       t@@ -152,7 +120,7 @@ class TcpInterface(threading.Thread):
                            s = ssl.wrap_socket(s, ssl_version=ssl.PROTOCOL_TLSv1, cert_reqs=ssl.CERT_REQUIRED, ca_certs=ca_path, do_handshake_on_connect=True)
                        except ssl.SSLError, e:
                            s = None
       -                if s and check_host_name(s.getpeercert(), self.host):
       +                if s and self.check_host_name(s.getpeercert(), self.host):
                            self.print_error("SSL certificate signed by CA")
                            return s
        
       t@@ -229,117 +197,131 @@ class TcpInterface(threading.Thread):
        
                return s
        
       -    def send_request(self, request, response_queue = None):
       +    def run(self):
       +        socket = self.get_socket()
       +        if socket:
       +            self.print_error("connected")
       +        self.queue.put((self.server, socket))
       +
       +class Interface:
       +    """The Interface class handles a socket connected to a single remote
       +    electrum server.  It's exposed API is:
       +
       +    - Member functions close(), fileno(), get_responses(), has_timed_out(),
       +      ping_required(), queue_request(), send_requests()
       +    - Member variable server.
       +    """
       +
       +    def __init__(self, server, socket):
       +        self.server = server
       +        self.host, _, _ = server.split(':')
       +        self.socket = socket
       +
       +        self.pipe = util.SocketPipe(socket)
       +        self.pipe.set_timeout(0.0)  # Don't wait for data
       +        # Dump network messages.  Set at runtime from the console.
       +        self.debug = False
       +        self.message_id = 0
       +        self.unsent_requests = []
       +        self.unanswered_requests = {}
       +        # Set last ping to zero to ensure immediate ping
       +        self.last_request = time.time()
       +        self.last_ping = 0
       +        self.closed_remotely = False
       +
       +    def print_error(self, *msg):
       +        util.print_error("[%s]" % self.host, *msg)
       +
       +    def fileno(self):
       +        # Needed for select
       +        return self.socket.fileno()
       +
       +    def close(self):
       +        if not self.closed_remotely:
       +            self.socket.shutdown(socket.SHUT_RDWR)
       +        self.socket.close()
       +
       +    def queue_request(self, request):
                '''Queue a request.'''
                self.request_time = time.time()
       -        self.request_queue.put((copy.deepcopy(request), response_queue))
       +        self.unsent_requests.append(request)
        
            def send_requests(self):
       -        '''Sends all queued requests'''
       -        while self.is_connected() and not self.request_queue.empty():
       -            request, response_queue = self.request_queue.get()
       -            method = request.get('method')
       -            params = request.get('params')
       -            r = {'id': self.message_id, 'method': method, 'params': params}
       -            try:
       -                self.pipe.send(r)
       -            except socket.error, e:
       -                self.print_error("socket error:", e)
       -                self.stop()
       -                return
       -            if self.debug:
       -                self.print_error("-->", r)
       -            self.unanswered_requests[self.message_id] = method, params, request.get('id'), response_queue
       +        '''Sends all queued requests.  Returns False on failure.'''
       +        def copy_request(orig):
       +            # Replace ID after making copy - mustn't change caller's copy
       +            request = orig.copy()
       +            request['id'] = self.message_id
                    self.message_id += 1
       +            if self.debug:
       +                self.print_error("-->", request, orig.get('id'))
       +            return request
       +
       +        requests_as_sent = map(copy_request, self.unsent_requests)
       +        try:
       +            self.pipe.send_all(requests_as_sent)
       +        except socket.error, e:
       +            self.print_error("socket error:", e)
       +            return False
       +        # unanswered_requests stores the original unmodified user
       +        # request, keyed by wire ID
       +        for n, request in enumerate(self.unsent_requests):
       +            self.unanswered_requests[requests_as_sent[n]['id']] = request
       +        self.unsent_requests = []
       +        return True
       +
       +    def ping_required(self):
       +        '''Maintains time since last ping.  Returns True if a ping should
       +        be sent.
       +        '''
       +        now = time.time()
       +        if now - self.last_ping > 60:
       +            self.last_ping = now
       +            return True
       +        return False
        
       -    def is_connected(self):
       -        '''True if status is connected'''
       -        return self._status == CS_CONNECTED and not self.disconnect
       -
       -    def stop(self):
       -        if not self.disconnect:
       -            self.disconnect = True
       -            self.print_error("disconnecting")
       -
       -    def maybe_ping(self):
       -        # ping the server with server.version
       -        if time.time() - self.ping_time > 60:
       -            self.send_request({'method':'server.version', 'params':[ELECTRUM_VERSION, PROTOCOL_VERSION]})
       -            self.ping_time = time.time()
       -        # stop interface if we have been waiting for more than 10 seconds
       -        if self.unanswered_requests and time.time() - self.request_time > 10 and self.pipe.idle_time() > 10:
       -            self.print_error("interface timeout", len(self.unanswered_requests))
       -            self.stop()
       -
       -    def get_and_process_response(self):
       -        if self.is_connected():
       +    def has_timed_out(self):
       +        '''Returns True if the interface has timed out.'''
       +        if (self.unanswered_requests and time.time() - self.request_time > 10
       +            and self.pipe.idle_time() > 10):
       +            self.print_error("timeout", len(self.unanswered_requests))
       +            return True
       +
       +        return False
       +
       +    def get_responses(self):
       +        '''Call if there is data available on the socket.  Returns a list of
       +        notifications and a list of responses.  The notifications are
       +        singleton unsolicited responses presumably as a result of
       +        prior subscriptions.  The responses are (request, response)
       +        pairs.  If the connection was closed remotely or the remote
       +        server is misbehaving, the last notification will be None.
       +        '''
       +        notifications, responses = [], []
       +        while True:
                    try:
                        response = self.pipe.get()
                    except util.timeout:
       -                return
       -            # If remote side closed the socket, SocketPipe closes our socket and returns None
       +                break
                    if response is None:
       -                self.disconnect = True
       +                notifications.append(None)
       +                self.closed_remotely = True
                        self.print_error("connection closed remotely")
       +                break
       +            if self.debug:
       +                self.print_error("<--", response)
       +            wire_id = response.pop('id', None)
       +            if wire_id is None:
       +                notifications.append(response)
       +            elif wire_id in self.unanswered_requests:
       +                request = self.unanswered_requests.pop(wire_id)
       +                responses.append((request, response))
                    else:
       -                self.process_response(response)
       +                notifications.append(None)
       +                self.print_error("unknown wire ID", wire_id)
       +                break
        
       -    def run(self):
       -        s = self.get_socket()
       -        if s:
       -            self.pipe = util.SocketPipe(s)
       -            s.settimeout(0.1)
       -            self.print_error("connected")
       -            self._status = CS_CONNECTED
       -            # Indicate to parent that we've connected
       -            self.notify_status()
       -            while self.is_connected():
       -                self.maybe_ping()
       -                self.send_requests()
       -                self.get_and_process_response()
       -            s.shutdown(socket.SHUT_RDWR)
       -            s.close()
       -
       -        # Also for the s is None case 
       -        self._status = CS_FAILED
       -        # Indicate to parent that the connection is now down
       -        self.notify_status()
       -
       -    def notify_status(self):
       -        '''Notify owner that we have just connected or just failed the connection.
       -        Owner determines which through e.g. testing is_connected()'''
       -        self.response_queue.put((self, None))
       -
       -
       -def _match_hostname(name, val):
       -    if val == name:
       -        return True
       -
       -    return val.startswith('*.') and name.endswith(val[1:])
       -
       -
       -def check_host_name(peercert, name):
       -    """Simple certificate/host name checker.  Returns True if the
       -    certificate matches, False otherwise."""
       -    # Check that the peer has supplied a certificate.
       -    # None/{} is not acceptable.
       -    if not peercert:
       -        return False
       -    if peercert.has_key("subjectAltName"):
       -        for typ, val in peercert["subjectAltName"]:
       -            if typ == "DNS" and _match_hostname(name, val):
       -                return True
       -    else:
       -        # Only check the subject DN if there is no subject alternative
       -        # name.
       -        cn = None
       -        for attr, val in peercert["subject"]:
       -            # Use most-specific (last) commonName attribute.
       -            if attr == "commonName":
       -                cn = val
       -        if cn is not None:
       -            return _match_hostname(name, cn)
       -    return False
       +        return notifications, responses
        
        
        def check_cert(host, cert):
       t@@ -361,7 +343,15 @@ def check_cert(host, cert):
            util.print_msg(m)
        
        
       +# Used by tests
       +def _match_hostname(name, val):
       +    if val == name:
       +        return True
       +
       +    return val.startswith('*.') and name.endswith(val[1:])
       +
        def test_certificates():
       +    from simple_config import SimpleConfig
            config = SimpleConfig()
            mydir = os.path.join(config.path, "certs")
            certs = os.listdir(mydir)
   DIR diff --git a/lib/network.py b/lib/network.py
       t@@ -3,7 +3,9 @@ import Queue
        import os
        import sys
        import random
       +import select
        import traceback
       +from collections import deque
        
        import socks
        import socket
       t@@ -11,9 +13,9 @@ import json
        
        import util
        from bitcoin import *
       -import interface
       +from interface import Connection, Interface
        from blockchain import Blockchain
       -from collections import deque
       +from version import ELECTRUM_VERSION, PROTOCOL_VERSION
        
        DEFAULT_PORTS = {'t':'50001', 's':'50002', 'h':'8081', 'g':'8082'}
        
       t@@ -119,11 +121,13 @@ def deserialize_server(server_str):
        def serialize_server(host, port, protocol):
            return str(':'.join([host, port, protocol]))
        
       -
        class Network(util.DaemonThread):
       -    """The Network class manages a set of connections to remote
       -    electrum servers, each connection is handled by its own
       -    thread object returned from Interface().  Its external API:
       +    """The Network class manages a set of connections to remote electrum
       +    servers, each connected socket is handled by an Interface() object.
       +    Connections are initiated by a Connection() thread which stops once
       +    the connection succeeds or fails.
       +
       +    Our external API:
        
            - Member functions get_header(), get_parameters(), get_status_value(),
                               new_blockchain_height(), set_parameters(), start(),
       t@@ -137,7 +141,6 @@ class Network(util.DaemonThread):
                self.config = SimpleConfig(config) if type(config) == type({}) else config
                self.num_server = 8 if not self.config.get('oneserver') else 0
                self.blockchain = Blockchain(self.config, self)
       -        self.queue = Queue.Queue()
                self.requests_queue = pipe.send_queue
                self.response_queue = pipe.get_queue
                # A deque of interface header requests, processed left-to-right
       t@@ -169,7 +172,7 @@ class Network(util.DaemonThread):
                self.subscribed_addresses = set()
                # cached address status
                self.addr_responses = {}
       -        # unanswered requests
       +        # Requests from client we've not seen a response to
                self.unanswered_requests = {}
                # retry times
                self.server_retry_time = time.time()
       t@@ -180,6 +183,8 @@ class Network(util.DaemonThread):
                self.interface = None
                self.interfaces = {}
                self.auto_connect = self.config.get('auto_connect', False)
       +        self.connecting = {}
       +        self.socket_queue = Queue.Queue()
                self.start_network(deserialize_server(self.default_server)[2],
                                   deserialize_proxy(self.config.get('proxy')))
        
       t@@ -224,19 +229,22 @@ class Network(util.DaemonThread):
                self.notify('status')
        
            def is_connected(self):
       -        return self.interface and self.interface.is_connected()
       +        return self.interface is not None
       +
       +    def queue_request(self, method, params):
       +        self.interface.queue_request({'method': method, 'params': params})
        
            def send_subscriptions(self):
                # clear cache
                self.cached_responses = {}
                self.print_error('sending subscriptions to', self.interface.server, len(self.unanswered_requests), len(self.subscribed_addresses))
                for r in self.unanswered_requests.values():
       -            self.interface.send_request(r)
       +            self.interface.queue_request(r)
                for addr in self.subscribed_addresses:
       -            self.interface.send_request({'method':'blockchain.address.subscribe','params':[addr]})
       -        self.interface.send_request({'method':'server.banner','params':[]})
       -        self.interface.send_request({'method':'server.peers.subscribe','params':[]})
       -        self.interface.send_request({'method':'blockchain.estimatefee','params':[2]})
       +            self.queue_request('blockchain.address.subscribe', [addr])
       +        self.queue_request('server.banner', [])
       +        self.queue_request('server.peers.subscribe', [])
       +        self.queue_request('blockchain.estimatefee', [2])
        
            def get_status_value(self, key):
                if key == 'status':
       t@@ -263,7 +271,7 @@ class Network(util.DaemonThread):
        
            def get_interfaces(self):
                '''The interfaces that are in connected state'''
       -        return [s for s, i in self.interfaces.items() if i.is_connected()]
       +        return self.interfaces.keys()
        
            def get_servers(self):
                if self.irc_servers:
       t@@ -280,12 +288,11 @@ class Network(util.DaemonThread):
                return out
        
            def start_interface(self, server):
       -        if not server in self.interfaces.keys():
       +        if (not server in self.interfaces and not server in self.connecting):
                    if server == self.default_server:
                        self.set_status('connecting')
       -            i = interface.Interface(server, self.queue, self.config)
       -            self.interfaces[i.server] = i
       -            i.start()
       +            c = Connection(server, self.socket_queue, self.config.path)
       +            self.connecting[server] = c
        
            def start_random_interface(self):
                exclude_set = self.disconnected_servers.union(set(self.interfaces))
       t@@ -312,6 +319,7 @@ class Network(util.DaemonThread):
        
            def start_network(self, protocol, proxy):
                assert not self.interface and not self.interfaces
       +        assert not self.connecting and self.socket_queue.empty()
                self.print_error('starting network')
                self.disconnected_servers = set([])
                self.protocol = protocol
       t@@ -320,10 +328,13 @@ class Network(util.DaemonThread):
        
            def stop_network(self):
                self.print_error("stopping network")
       -        for i in self.interfaces.values():
       -            i.stop()
       -        self.interface = None
       -        self.interfaces = {}
       +        for interface in self.interfaces.values():
       +            self.close_interface(interface)
       +        assert self.interface is None
       +        assert not self.interfaces
       +        self.connecting = {}
       +        # Get a new queue - no old pending connections thanks!
       +        self.socket_queue = Queue.Queue()
        
            def set_parameters(self, host, port, protocol, proxy, auto_connect):
                self.auto_connect = auto_connect
       t@@ -339,7 +350,10 @@ class Network(util.DaemonThread):
                    self.switch_lagging_interface()
        
            def switch_to_random_interface(self):
       +        '''Switch to a random connected server other than the current one'''
                servers = self.get_interfaces()    # Those in connected state
       +        if self.default_server in servers:
       +            servers.remove(self.default_server)
                if servers:
                    self.switch_to_interface(random.choice(servers))
        
       t@@ -362,30 +376,28 @@ class Network(util.DaemonThread):
                    self.start_interface(server)
                    return
                i = self.interfaces[server]
       -        if not i.is_connected():
       -            # do nothing; we will switch once connected
       -            return
                if self.interface != i:
                    self.print_error("switching to", server)
                    # stop any current interface in order to terminate subscriptions
       -            self.stop_interface()
       +            self.close_interface(self.interface)
                    self.interface = i
                    self.addr_responses = {}
                    self.send_subscriptions()
                    self.set_status('connected')
                    self.notify('updated')
        
       -    def stop_interface(self):
       -        if self.interface:
       -            self.interface.stop()
       -            self.interface = None
       +    def close_interface(self, interface):
       +        if interface:
       +            self.interfaces.pop(interface.server)
       +            if interface.server == self.default_server:
       +                self.interface = None
       +            interface.close()
        
       -    def add_recent_server(self, i):
       +    def add_recent_server(self, server):
                # list is ordered
       -        s = i.server
       -        if s in self.recent_servers:
       -            self.recent_servers.remove(s)
       -        self.recent_servers.insert(0,s)
       +        if server in self.recent_servers:
       +            self.recent_servers.remove(server)
       +        self.recent_servers.insert(0, server)
                self.recent_servers = self.recent_servers[0:20]
                self.save_recent_servers()
        
       t@@ -393,70 +405,75 @@ class Network(util.DaemonThread):
                self.switch_lagging_interface(i.server)
                self.notify('updated')
        
       -    def process_if_notification(self, i):
       -        '''Handle interface addition and removal through notifications'''
       -        if i.is_connected():
       -            self.add_recent_server(i)
       -            i.send_request({'method':'blockchain.headers.subscribe','params':[]})
       -            if i.server == self.default_server:
       -                self.switch_to_interface(i.server)
       -        else:
       -            self.interfaces.pop(i.server, None)
       -            self.heights.pop(i.server, None)
       -            if i == self.interface:
       -                self.interface = None
       -                self.addr_responses = {}
       -                self.set_status('disconnected')
       -            self.disconnected_servers.add(i.server)
       -        # Our set of interfaces changed
       -        self.notify('interfaces')
       -
       -    def process_response(self, i, response):
       -        # the id comes from the daemon or the network proxy
       -        _id = response.get('id')
       -        if _id is not None:
       -            if i != self.interface:
       -                return
       -            self.unanswered_requests.pop(_id)
       -
       -        method = response.get('method')
       +    def process_response(self, interface, response):
       +        error = response.get('error')
                result = response.get('result')
       -        if method == 'blockchain.headers.subscribe':
       -            self.on_header(i, response)
       +        method = response.get('method')
       +
       +        # We handle some responses; return the rest to the client.
       +        if method == 'server.version':
       +            interface.server_version = result
       +        elif method == 'blockchain.headers.subscribe':
       +            if error is None:
       +                self.on_header(interface, result)
                elif method == 'server.peers.subscribe':
       -            self.irc_servers = parse_servers(result)
       -            self.notify('servers')
       +            if error is None:
       +                self.irc_servers = parse_servers(result)
       +                self.notify('servers')
                elif method == 'server.banner':
       -            self.banner = result
       -            self.notify('banner')
       +            if error is None:
       +                self.banner = result
       +                self.notify('banner')
                elif method == 'blockchain.estimatefee':
       -            from bitcoin import COIN
       -            self.fee = int(result * COIN)
       -            self.print_error("recommended fee", self.fee)
       -            self.notify('fee')
       -        elif method == 'blockchain.address.subscribe':
       -            addr = response.get('params')[0]
       -            self.addr_responses[addr] = result
       -            self.response_queue.put(response)
       +            if error is None:
       +                self.fee = int(result * COIN)
       +                self.print_error("recommended fee", self.fee)
       +                self.notify('fee')
                elif method == 'blockchain.block.get_chunk':
       -            self.on_get_chunk(i, response)
       +            self.on_get_chunk(interface, response)
                elif method == 'blockchain.block.get_header':
       -            self.on_get_header(i, response)
       +            self.on_get_header(interface, response)
                else:
       +            # Cache address subscription results
       +            if method == 'blockchain.address.subscribe' and error is None:
       +                addr = response['params'][0]
       +                self.addr_responses[addr] = result
                    self.response_queue.put(response)
        
       -    def handle_requests(self):
       -        '''Some requests require connectivity, others we handle locally in
       -        process_request() and must do so in order to e.g. prevent the
       -        daemon seeming unresponsive.
       -        '''
       -        unhandled = []
       +    def process_responses(self, interface):
       +        notifications, responses = interface.get_responses()
       +
       +        for request, response in responses:
       +            # Client ID was given by the daemon or proxy
       +            client_id = request.get('id')
       +            if client_id is not None:
       +                if interface != self.interface:
       +                    continue
       +                self.unanswered_requests.pop(client_id)
       +            # Copy the request method and params to the response
       +            response['method'] = request.get('method')
       +            response['params'] = request.get('params')
       +            response['id'] = client_id
       +            self.process_response(interface, response)
       +
       +        for response in notifications:
       +            if not response:  # Closed remotely
       +                self.connection_down(interface.server)
       +                break
       +            # Rewrite response shape to match subscription request response
       +            method = response.get('method')
       +            if method == 'blockchain.headers.subscribe':
       +                response['result'] = response['params'][0]
       +                response['params'] = []
       +            elif method == 'blockchain.address.subscribe':
       +                params = response['params']
       +                response['params'] = [params[0]]  # addr
       +                response['result'] = params[1]
       +            self.process_response(interface, response)
       +
       +    def handle_incoming_requests(self):
                while not self.requests_queue.empty():
       -            request = self.requests_queue.get()
       -            if not self.process_request(request):
       -                unhandled.append(request)
       -        for request in unhandled:
       -            self.requests_queue.put(request)
       +            self.process_request(self.requests_queue.get())
        
            def process_request(self, request):
                '''Returns true if the request was processed.'''
       t@@ -487,22 +504,62 @@ class Network(util.DaemonThread):
        
                # This request needs connectivity.  If we don't have an
                # interface, we cannot process it.
       -        if not self.is_connected():
       +        if not self.interface:
                    return False
        
                self.unanswered_requests[_id] = request
       -        self.interface.send_request(request)
       +        self.interface.queue_request(request)
                return True
        
       -    def check_interfaces(self):
       +    def connection_down(self, server):
       +        '''A connection to server either went down, or was never made.
       +        We distinguish by whether it is in self.interfaces.'''
       +        self.disconnected_servers.add(server)
       +        if server == self.default_server:
       +            self.set_status('disconnected')
       +        if server in self.interfaces:
       +            self.close_interface(self.interfaces[server])
       +            self.heights.pop(server, None)
       +            self.notify('interfaces')
       +
       +    def new_interface(self, server, socket):
       +        self.add_recent_server(server)
       +        self.interfaces[server] = interface = Interface(server, socket)
       +        interface.queue_request({'method': 'blockchain.headers.subscribe',
       +                                 'params': []})
       +        if server == self.default_server:
       +            self.switch_to_interface(server)
       +        self.notify('interfaces')
       +
       +    def maintain_sockets(self):
       +        '''Socket maintenance.'''
       +        # Responses to connection attempts?
       +        while not self.socket_queue.empty():
       +            server, socket = self.socket_queue.get()
       +            self.connecting.pop(server)
       +            if socket:
       +                self.new_interface(server, socket)
       +            else:
       +                self.connection_down(server)
       +
       +        # Send pings and shut down stale interfaces
       +        for interface in self.interfaces.values():
       +            if interface.has_timed_out():
       +                self.connection_down(interface.server)
       +            elif interface.ping_required():
       +                version_req = {'method': 'server.version',
       +                               'params': [ELECTRUM_VERSION, PROTOCOL_VERSION]}
       +                interface.queue_request(version_req)
       +
                now = time.time()
                # nodes
       -        if len(self.interfaces) < self.num_server:
       +        if len(self.interfaces) + len(self.connecting) < self.num_server:
                    self.start_random_interface()
                    if now - self.nodes_retry_time > NODES_RETRY_INTERVAL:
                        self.print_error('network: retrying connections')
                        self.disconnected_servers = set([])
                        self.nodes_retry_time = now
       +
                # main interface
                if not self.is_connected():
                    if self.auto_connect:
       t@@ -517,7 +574,8 @@ class Network(util.DaemonThread):
        
            def request_chunk(self, interface, data, idx):
                interface.print_error("requesting chunk %d" % idx)
       -        interface.send_request({'method':'blockchain.block.get_chunk', 'params':[idx]})
       +        interface.queue_request({'method':'blockchain.block.get_chunk',
       +                                 'params':[idx]})
                data['chunk_idx'] = idx
                data['req_time'] = time.time()
        
       t@@ -537,7 +595,8 @@ class Network(util.DaemonThread):
        
            def request_header(self, interface, data, height):
                interface.print_error("requesting header %d" % height)
       -        interface.send_request({'method':'blockchain.block.get_header', 'params':[height]})
       +        interface.queue_request({'method':'blockchain.block.get_header',
       +                                 'params':[height]})
                data['header_height'] = height
                data['req_time'] = time.time()
                if not 'chain' in data:
       t@@ -563,7 +622,9 @@ class Network(util.DaemonThread):
                            self.request_header(interface, data, next_height)
        
            def bc_request_headers(self, interface, data):
       -        '''Send a request for the next header, or a chunk of them, if necessary'''
       +        '''Send a request for the next header, or a chunk of them,
       +        if necessary.
       +        '''
                local_height, if_height = self.get_local_height(), data['if_height']
                if if_height <= local_height:
                    return False
       t@@ -575,11 +636,12 @@ class Network(util.DaemonThread):
        
            def handle_bc_requests(self):
                '''Work through each interface that has notified us of a new header.
       -        Send it requests if it is ahead of our blockchain object'''
       +        Send it requests if it is ahead of our blockchain object.
       +        '''
                while self.bc_requests:
                    interface, data = self.bc_requests.popleft()
                    # If the connection was lost move on
       -            if not interface.is_connected():
       +            if not interface in self.interfaces.values():
                        continue
        
                    req_time = data.get('req_time')
       t@@ -590,36 +652,39 @@ class Network(util.DaemonThread):
                            continue
                    elif time.time() - req_time > 10:
                        interface.print_error("blockchain request timed out")
       -                interface.stop()
       +                self.connection_down(interface.server)
                        continue
                    # Put updated request state back at head of deque
                    self.bc_requests.appendleft((interface, data))
                    break
        
       +    def wait_on_sockets(self):
       +        # Python docs say Windows doesn't like empty selects.
       +        # Sleep to prevent busy looping
       +        if not self.interfaces:
       +            time.sleep(0.1)
       +            return
       +        rin = [i for i in self.interfaces.values()]
       +        win = [i for i in self.interfaces.values() if i.unsent_requests]
       +        rout, wout, xout = select.select(rin, win, [], 0.1)
       +        assert not xout
       +        for interface in wout:
       +            interface.send_requests()
       +        for interface in rout:
       +            self.process_responses(interface)
       +
            def run(self):
                self.blockchain.init()
                while self.is_running():
       -            self.check_interfaces()
       -            self.handle_requests()
       +            self.maintain_sockets()
       +            self.wait_on_sockets()
       +            self.handle_incoming_requests()
                    self.handle_bc_requests()
       -            try:
       -                i, response = self.queue.get(timeout=0.1)
       -            except Queue.Empty:
       -                continue
       -
       -            # if response is None it is a notification about the interface
       -            if response is None:
       -                self.process_if_notification(i)
       -            else:
       -                self.process_response(i, response)
        
                self.stop_network()
                self.print_error("stopped")
        
       -    def on_header(self, i, r):
       -        header = r.get('result')
       -        if not header:
       -            return
       +    def on_header(self, i, header):
                height = header.get('block_height')
                if not height:
                    return