asyncio: don't stop network on shutdown (slow)

contrib/deterministic-build/requirements.txt

@@ -7,7 +7,7 @@ jsonrpclib-pelix==0.3.1
 pbkdf2==1.3
 protobuf==3.5.1
 pyaes==1.6.1
-PySocks==1.6.8
+aiosocks==0.2.6
 qrcode==5.3
 requests==2.18.4
 six==1.11.0

contrib/requirements/requirements.txt

@@ -6,4 +6,4 @@ qrcode
 protobuf
 dnspython
 jsonrpclib-pelix
-PySocks>=1.6.6
+aiosocks

lib/__init__.py

@@ -4,7 +4,7 @@ from .wallet import Synchronizer, Wallet
 from .storage import WalletStorage
 from .coinchooser import COIN_CHOOSERS
 from .network import Network, pick_random_server
-from .interface import Connection, Interface
+from .interface import Interface
 from .simple_config import SimpleConfig, get_config, set_config
 from . import bitcoin
 from . import transaction

lib/interface.py

@@ -22,288 +22,257 @@
 # ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 # CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 # SOFTWARE.
+import aiosocks
 import os
+import stat
 import re
-import socket
 import ssl
 import sys
 import threading
 import time
 import traceback
+import asyncio
+import json
+import asyncio.streams
+from asyncio.sslproto import SSLProtocol
+import io
 
 import requests
 
-from .util import print_error
+from aiosocks.errors import SocksError
+from concurrent.futures import TimeoutError
 
 ca_path = requests.certs.where()
 
+from .util import print_error
+from .ssl_in_socks import sslInSocksReaderWriter
 from . import util
 from . import x509
 from . import pem
 
-
+def get_ssl_context(cert_reqs, ca_certs):
-def Connection(server, queue, config_path):
-    """Makes asynchronous connections to a remote electrum server.
-    Returns the running thread that is making the connection.
-
-    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.rsplit(':', 2)
-    if not protocol in 'st':
-        raise Exception('Unknown protocol: %s' % protocol)
-    c = TcpConnection(server, queue, config_path)
-    c.start()
-    return c
-
-
-class TcpConnection(threading.Thread, util.PrintError):
-
-    def __init__(self, server, queue, config_path):
-        threading.Thread.__init__(self)
-        self.config_path = config_path
-        self.queue = queue
-        self.server = server
-        self.host, self.port, self.protocol = self.server.rsplit(':', 2)
-        self.host = str(self.host)
-        self.port = int(self.port)
-        self.use_ssl = (self.protocol == 's')
-        self.daemon = True
-
-    def diagnostic_name(self):
-        return self.host
-
-    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 'subjectAltName' in peercert:
-            for typ, val in peercert["subjectAltName"]:
-                if typ == "DNS" and val == name:
-                    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 cn == name
-        return False
-
-    def get_simple_socket(self):
-        try:
-            l = socket.getaddrinfo(self.host, self.port, socket.AF_UNSPEC, socket.SOCK_STREAM)
-        except socket.gaierror:
-            self.print_error("cannot resolve hostname")
-            return
-        e = None
-        for res in l:
-            try:
-                s = socket.socket(res[0], socket.SOCK_STREAM)
-                s.settimeout(10)
-                s.connect(res[4])
-                s.settimeout(2)
-                s.setsockopt(socket.SOL_SOCKET, socket.SO_KEEPALIVE, 1)
-                return s
-            except BaseException as _e:
-                e = _e
-                continue
-        else:
-            self.print_error("failed to connect", str(e))
-
-    @staticmethod
-    def get_ssl_context(cert_reqs, ca_certs):
     context = ssl.create_default_context(purpose=ssl.Purpose.SERVER_AUTH, cafile=ca_certs)
     context.check_hostname = False
     context.verify_mode = cert_reqs
-
     context.options |= ssl.OP_NO_SSLv2
     context.options |= ssl.OP_NO_SSLv3
     context.options |= ssl.OP_NO_TLSv1
-
     return context
 
-    def get_socket(self):
-        if self.use_ssl:
-            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()
-                if s is None:
-                    return
-                # try with CA first
-                try:
-                    context = self.get_ssl_context(cert_reqs=ssl.CERT_REQUIRED, ca_certs=ca_path)
-                    s = context.wrap_socket(s, do_handshake_on_connect=True)
-                except ssl.SSLError as e:
-                    print_error(e)
-                    s = None
-                except:
-                    return
-
-                if s and self.check_host_name(s.getpeercert(), self.host):
-                    self.print_error("SSL certificate signed by CA")
-                    return s
-                # get server certificate.
-                # Do not use ssl.get_server_certificate because it does not work with proxy
-                s = self.get_simple_socket()
-                if s is None:
-                    return
-                try:
-                    context = self.get_ssl_context(cert_reqs=ssl.CERT_NONE, ca_certs=None)
-                    s = context.wrap_socket(s)
-                except ssl.SSLError as e:
-                    self.print_error("SSL error retrieving SSL certificate:", e)
-                    return
-                except:
-                    return
-
-                dercert = s.getpeercert(True)
-                s.close()
-                cert = ssl.DER_cert_to_PEM_cert(dercert)
-                # workaround android bug
-                cert = re.sub("([^\n])-----END CERTIFICATE-----","\\1\n-----END CERTIFICATE-----",cert)
-                temporary_path = cert_path + '.temp'
-                with open(temporary_path,"w") as f:
-                    f.write(cert)
-            else:
-                is_new = False
-
-        s = self.get_simple_socket()
-        if s is None:
-            return
-
-        if self.use_ssl:
-            try:
-                context = self.get_ssl_context(cert_reqs=ssl.CERT_REQUIRED,
-                                               ca_certs=(temporary_path if is_new else cert_path))
-                s = context.wrap_socket(s, do_handshake_on_connect=True)
-            except socket.timeout:
-                self.print_error('timeout')
-                return
-            except ssl.SSLError as e:
-                self.print_error("SSL error:", e)
-                if e.errno != 1:
-                    return
-                if is_new:
-                    rej = cert_path + '.rej'
-                    if os.path.exists(rej):
-                        os.unlink(rej)
-                    os.rename(temporary_path, rej)
-                else:
-                    with open(cert_path) as f:
-                        cert = f.read()
-                    try:
-                        b = pem.dePem(cert, 'CERTIFICATE')
-                        x = x509.X509(b)
-                    except:
-                        traceback.print_exc(file=sys.stderr)
-                        self.print_error("wrong certificate")
-                        return
-                    try:
-                        x.check_date()
-                    except:
-                        self.print_error("certificate has expired:", cert_path)
-                        os.unlink(cert_path)
-                        return
-                    self.print_error("wrong certificate")
-                if e.errno == 104:
-                    return
-                return
-            except BaseException as e:
-                self.print_error(e)
-                traceback.print_exc(file=sys.stderr)
-                return
-
-            if is_new:
-                self.print_error("saving certificate")
-                os.rename(temporary_path, cert_path)
-
-        return s
-
-    def run(self):
-        socket = self.get_socket()
-        if socket:
-            self.print_error("connected")
-        self.queue.put((self.server, socket))
-
-
 class Interface(util.PrintError):
     """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(),
+    - Member functions close(), fileno(), get_response(), has_timed_out(),
-      ping_required(), queue_request(), send_requests()
+      ping_required(), queue_request(), send_request()
     - Member variable server.
     """
 
-    def __init__(self, server, socket):
+    def __init__(self, server, config_path, proxy_config, is_running, exception_handler):
-        self.server = server
+        self.error_future = asyncio.Future()
-        self.host, _, _ = server.rsplit(':', 2)
+        self.error_future.add_done_callback(exception_handler)
-        self.socket = socket
+        self.is_running = lambda: is_running() and not self.error_future.done()
+        self.addr = self.auth = None
+        if proxy_config is not None:
+            if proxy_config["mode"] == "socks5":
+                self.addr = aiosocks.Socks5Addr(proxy_config["host"], proxy_config["port"])
+                self.auth = aiosocks.Socks5Auth(proxy_config["user"], proxy_config["password"]) if proxy_config["user"] != "" else None
+            elif proxy_config["mode"] == "socks4":
+                self.addr = aiosocks.Socks4Addr(proxy_config["host"], proxy_config["port"])
+                self.auth = aiosocks.Socks4Auth(proxy_config["password"]) if proxy_config["password"] != "" else None
+            else:
+                raise Exception("proxy mode not supported")
 
-        self.pipe = util.SocketPipe(socket)
+        self.server = server
-        self.pipe.set_timeout(0.0)  # Don't wait for data
+        self.config_path = config_path
+        host, port, protocol = self.server.split(':')
+        self.host = host
+        self.port = int(port)
+        self.use_ssl = (protocol=='s')
+        self.reader = self.writer = None
+        self.lock = asyncio.Lock()
         # Dump network messages.  Set at runtime from the console.
         self.debug = False
-        self.unsent_requests = []
+        self.unsent_requests = asyncio.PriorityQueue()
         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
+        self.buf = bytes()
+
+    def conn_coro(self, context):
+        return asyncio.open_connection(self.host, self.port, ssl=context)
+
+    async def _save_certificate(self, cert_path, require_ca):
+        dercert = None
+        if require_ca:
+            context = get_ssl_context(cert_reqs=ssl.CERT_REQUIRED, ca_certs=ca_path)
+        else:
+            context = get_ssl_context(cert_reqs=ssl.CERT_NONE, ca_certs=None)
+        if self.addr is not None:
+            self.print_error("can't save certificate through socks!")
+            # just save the empty file to force use of PKI
+            # this will break all self-signed servers, of course
+            cert = ""
+        else:
+            reader, writer = await asyncio.wait_for(self.conn_coro(context), 3)
+            dercert = writer.get_extra_info('ssl_object').getpeercert(True)
+            # an exception will be thrown by now if require_ca is True (e.g. a certificate was supplied)
+            writer.close()
+            if not require_ca:
+                cert = ssl.DER_cert_to_PEM_cert(dercert)
+            else:
+                # Don't pin a CA signed certificate
+                cert = ""
+        temporary_path = cert_path + '.temp'
+        with open(temporary_path, "w") as f:
+            f.write(cert)
+        return temporary_path
+
+    async def _get_read_write(self):
+        async with self.lock:
+            if self.reader is not None and self.writer is not None:
+                return self.reader, self.writer, True
+            if self.use_ssl:
+                cert_path = os.path.join(self.config_path, 'certs', self.host)
+                if not os.path.exists(cert_path):
+                    temporary_path = None
+                    # first, we try to save a certificate signed through the PKI
+                    try:
+                      temporary_path = await self._save_certificate(cert_path, True)
+                    except ssl.SSLError:
+                      pass
+                    except (TimeoutError, OSError) as e:
+                      if not self.error_future.done(): self.error_future.set_result(e)
+                      raise
+                    # if the certificate verification failed, we try to save a self-signed certificate
+                    if not temporary_path:
+                      try:
+                        temporary_path = await self._save_certificate(cert_path, False)
+                      # we also catch SSLError here, but it shouldn't matter since no certificate is required,
+                      # so the SSLError wouldn't mean certificate validation failed
+                      except (TimeoutError, OSError) as e:
+                        if not self.error_future.done(): self.error_future.set_result(e)
+                        raise
+                    if not temporary_path:
+                        if not self.error_future.done(): self.error_future.set_result(ConnectionError("Could not get certificate"))
+                        raise ConnectionError("Could not get certificate on second try")
+
+                    is_new = True
+                else:
+                    is_new = False
+                ca_certs = temporary_path if is_new else cert_path
+
+                size = os.stat(ca_certs)[stat.ST_SIZE]
+                self_signed = size != 0
+                if not self_signed:
+                    ca_certs = ca_path
+            try:
+                if self.addr is not None:
+                    if not self.use_ssl:
+                        open_coro = aiosocks.open_connection(proxy=self.addr, proxy_auth=self.auth, dst=(self.host, self.port))
+                        self.reader, self.writer = await asyncio.wait_for(open_coro, 5)
+                    else:
+                        ssl_in_socks_coro = sslInSocksReaderWriter(self.addr, self.auth, self.host, self.port, ca_certs)
+                        self.reader, self.writer = await asyncio.wait_for(ssl_in_socks_coro, 5)
+                else:
+                    context = get_ssl_context(cert_reqs=ssl.CERT_REQUIRED, ca_certs=ca_certs) if self.use_ssl else None
+                    self.reader, self.writer = await asyncio.wait_for(self.conn_coro(context), 5)
+            except TimeoutError:
+                self.print_error("TimeoutError after getting certificate successfully...")
+                raise
+            except ssl.SSLError:
+                # FIXME TODO
+                assert not self_signed, "we shouldn't reject self-signed here since the certificate has been saved (has size {})".format(size)
+                raise
+            except BaseException as e:
+                if self.is_running():
+                    if not isinstance(e, OSError):
+                        traceback.print_exc()
+                        self.print_error("Previous exception will now be reraised")
+                raise e
+            if self.use_ssl and is_new:
+                self.print_error("saving new certificate for", self.host)
+                os.rename(temporary_path, cert_path)
+            return self.reader, self.writer, False
+
+    async def send_all(self, list_of_requests):
+        _, w, usedExisting = await self._get_read_write()
+        starttime = time.time()
+        for i in list_of_requests:
+            w.write(json.dumps(i).encode("ascii") + b"\n")
+        await w.drain()
+        if time.time() - starttime > 2.5:
+            self.print_error("send_all: sending is taking too long. Used existing connection: ", usedExisting)
+            raise ConnectionError("sending is taking too long")
+
+    def close(self):
+        if self.writer:
+            self.writer.close()
+
+    def _try_extract(self):
+        try:
+            pos = self.buf.index(b"\n")
+        except ValueError:
+            return
+        obj = self.buf[:pos]
+        try:
+            obj = json.loads(obj.decode("ascii"))
+        except ValueError:
+            return
+        else:
+            self.buf = self.buf[pos+1:]
+            self.last_action = time.time()
+            return obj
+    async def get(self):
+        reader, _, _ = await self._get_read_write()
+
+        while self.is_running():
+            tried = self._try_extract()
+            if tried: return tried
+            temp = io.BytesIO()
+            try:
+                data = await asyncio.wait_for(reader.read(2**10), 1)
+                temp.write(data)
+            except asyncio.TimeoutError:
+                continue
+            self.buf += temp.getvalue()
+
+    def idle_time(self):
+        return time.time() - self.last_action
 
     def diagnostic_name(self):
         return self.host
 
-    def fileno(self):
+    async def queue_request(self, *args):  # method, params, _id
-        # Needed for select
-        return self.socket.fileno()
-
-    def close(self):
-        if not self.closed_remotely:
-            try:
-                self.socket.shutdown(socket.SHUT_RDWR)
-            except socket.error:
-                pass
-        self.socket.close()
-
-    def queue_request(self, *args):  # method, params, _id
         '''Queue a request, later to be send with send_requests when the
         socket is available for writing.
         '''
         self.request_time = time.time()
-        self.unsent_requests.append(args)
+        await self.unsent_requests.put((self.request_time, args))
+        await self.unsent_requests.join()
 
     def num_requests(self):
         '''Keep unanswered requests below 100'''
         n = 100 - len(self.unanswered_requests)
-        return min(n, len(self.unsent_requests))
+        return min(n, self.unsent_requests.qsize())
 
-    def send_requests(self):
+    async def send_request(self):
-        '''Sends queued requests.  Returns False on failure.'''
+        '''Sends a queued request.'''
         make_dict = lambda m, p, i: {'method': m, 'params': p, 'id': i}
         n = self.num_requests()
-        wire_requests = self.unsent_requests[0:n]
+        prio, request = await self.unsent_requests.get()
         try:
-            self.pipe.send_all([make_dict(*r) for r in wire_requests])
+            await self.send_all([make_dict(*request)])
-        except socket.error as e:
+        except (SocksError, OSError, TimeoutError) as e:
-            self.print_error("socket error:", e)
+            if type(e) is SocksError:
-            return False
+                self.print_error(e)
-        self.unsent_requests = self.unsent_requests[n:]
+            await self.unsent_requests.put((prio, request))
-        for request in wire_requests:
+            return
+        self.unsent_requests.task_done()
         if self.debug:
             self.print_error("-->", request)
         self.unanswered_requests[request[2]] = request
-        return True
+        self.last_action = time.time()
 
     def ping_required(self):
         '''Maintains time since last ping.  Returns True if a ping should
@@ -317,14 +286,14 @@ class Interface(util.PrintError):
 
     def has_timed_out(self):
         '''Returns True if the interface has timed out.'''
+        if self.error_future.done(): return True
         if (self.unanswered_requests and time.time() - self.request_time > 10
-            and self.pipe.idle_time() > 10):
+            and self.idle_time() > 10):
             self.print_error("timeout", len(self.unanswered_requests))
             return True
-
         return False
 
-    def get_responses(self):
+    async def get_response(self):
         '''Call if there is data available on the socket.  Returns a list of
         (request, response) pairs.  Notifications are singleton
         unsolicited responses presumably as a result of prior
@@ -333,34 +302,25 @@ class Interface(util.PrintError):
         corresponding request.  If the connection was closed remotely
         or the remote server is misbehaving, a (None, None) will appear.
         '''
-        responses = []
+        response = await self.get()
-        while True:
-            try:
-                response = self.pipe.get()
-            except util.timeout:
-                break
         if not type(response) is dict:
-                responses.append((None, None))
             if response is None:
                 self.closed_remotely = True
+                if self.is_running():
                     self.print_error("connection closed remotely")
-                break
+            return None, None
         if self.debug:
             self.print_error("<--", response)
         wire_id = response.get('id', None)
         if wire_id is None:  # Notification
-                responses.append((None, response))
+            return None, response
         else:
             request = self.unanswered_requests.pop(wire_id, None)
             if request:
-                    responses.append((request, response))
+                return request, response
             else:
                 self.print_error("unknown wire ID", wire_id)
-                    responses.append((None, None)) # Signal
+                return None, None # Signal
-                    break
-
-        return responses
-
 
 def check_cert(host, cert):
     try:

lib/network.py

@@ -20,6 +20,9 @@
 # ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 # CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 # SOFTWARE.
+import sys
+import collections
+from functools import partial
 import time
 import queue
 import os
@@ -30,15 +33,15 @@ import re
 import select
 from collections import defaultdict
 import threading
-import socket
 import json
+import asyncio
+import traceback
 
-import socks
 from . import util
 from . import bitcoin
 from .bitcoin import *
 from . import constants
-from .interface import Connection, Interface
+from .interface import Interface
 from . import blockchain
 from .version import ELECTRUM_VERSION, PROTOCOL_VERSION
 from .i18n import _
@@ -47,6 +50,7 @@ from .i18n import _
 NODES_RETRY_INTERVAL = 60
 SERVER_RETRY_INTERVAL = 10
 
+from concurrent.futures import TimeoutError, CancelledError
 
 def parse_servers(result):
     """ parse servers list into dict format"""
@@ -78,7 +82,7 @@ def filter_version(servers):
     def is_recent(version):
         try:
             return util.normalize_version(version) >= util.normalize_version(PROTOCOL_VERSION)
-        except Exception as e:
+        except BaseException as e:
             return False
     return {k: v for k, v in servers.items() if is_recent(v.get('version'))}
 
@@ -159,10 +163,18 @@ class Network(util.DaemonThread):
 
     - Member functions get_header(), get_interfaces(), get_local_height(),
           get_parameters(), get_server_height(), get_status_value(),
-          is_connected(), set_parameters(), stop()
+          is_connected(), set_parameters(), stop(), follow_chain()
     """
 
     def __init__(self, config=None):
+        self.lock = threading.Lock()
+        # callbacks set by the GUI
+        self.callbacks = defaultdict(list)
+        self.set_status("disconnected")
+        self.disconnected_servers = {}
+        self.connecting = {}
+        self.stopped = True
+        asyncio.set_event_loop(None)
         if config is None:
             config = {}  # Do not use mutables as default values!
         util.DaemonThread.__init__(self)
@@ -184,8 +196,6 @@ class Network(util.DaemonThread):
                 self.default_server = None
         if not self.default_server:
             self.default_server = pick_random_server()
-        self.lock = threading.Lock()
-        self.pending_sends = []
         self.message_id = 0
         self.debug = False
         self.irc_servers = {} # returned by interface (list from irc)
@@ -197,8 +207,6 @@ class Network(util.DaemonThread):
         # callbacks passed with subscriptions
         self.subscriptions = defaultdict(list)
         self.sub_cache = {}
-        # callbacks set by the GUI
-        self.callbacks = defaultdict(list)
 
         dir_path = os.path.join( self.config.path, 'certs')
         if not os.path.exists(dir_path):
@@ -214,16 +222,11 @@ class Network(util.DaemonThread):
         self.server_retry_time = time.time()
         self.nodes_retry_time = time.time()
         # kick off the network.  interface is the main server we are currently
-        # communicating with.  interfaces is the set of servers we are connecting
+        # communicating with.  interfaces is the set of servers we are connected
         # to or have an ongoing connection with
         self.interface = None
         self.interfaces = {}
         self.auto_connect = self.config.get('auto_connect', True)
-        self.connecting = set()
-        self.requested_chunks = set()
-        self.socket_queue = queue.Queue()
-        self.start_network(deserialize_server(self.default_server)[2],
-                           deserialize_proxy(self.config.get('proxy')))
 
     def register_callback(self, callback, events):
         with self.lock:
@@ -290,19 +293,20 @@ class Network(util.DaemonThread):
     def is_up_to_date(self):
         return self.unanswered_requests == {}
 
-    def queue_request(self, method, params, interface=None):
+    async def queue_request(self, method, params, interface=None):
         # If you want to queue a request on any interface it must go
         # through this function so message ids are properly tracked
         if interface is None:
+            assert self.interface is not None
             interface = self.interface
         message_id = self.message_id
         self.message_id += 1
         if self.debug:
             self.print_error(interface.host, "-->", method, params, message_id)
-        interface.queue_request(method, params, message_id)
+        await interface.queue_request(method, params, message_id)
         return message_id
 
-    def send_subscriptions(self):
+    async def send_subscriptions(self):
         self.print_error('sending subscriptions to', self.interface.server, len(self.unanswered_requests), len(self.subscribed_addresses))
         self.sub_cache.clear()
         # Resend unanswered requests
@@ -310,24 +314,27 @@ class Network(util.DaemonThread):
         self.unanswered_requests = {}
         if self.interface.ping_required():
             params = [ELECTRUM_VERSION, PROTOCOL_VERSION]
-            self.queue_request('server.version', params, self.interface)
+            await self.queue_request('server.version', params, self.interface)
         for request in requests:
-            message_id = self.queue_request(request[0], request[1])
+            message_id = await self.queue_request(request[0], request[1])
             self.unanswered_requests[message_id] = request
-        self.queue_request('server.banner', [])
+        await self.queue_request('server.banner', [])
-        self.queue_request('server.donation_address', [])
+        await self.queue_request('server.donation_address', [])
-        self.queue_request('server.peers.subscribe', [])
+        await self.queue_request('server.peers.subscribe', [])
-        self.request_fee_estimates()
+        await self.request_fee_estimates()
-        self.queue_request('blockchain.relayfee', [])
+        await self.queue_request('blockchain.relayfee', [])
+        if self.interface.ping_required():
+            params = [ELECTRUM_VERSION, PROTOCOL_VERSION]
+            await self.queue_request('server.version', params, self.interface)
         for h in self.subscribed_addresses:
-            self.queue_request('blockchain.scripthash.subscribe', [h])
+            await self.queue_request('blockchain.scripthash.subscribe', [h])
 
-    def request_fee_estimates(self):
+    async def request_fee_estimates(self):
         from .simple_config import FEE_ETA_TARGETS
         self.config.requested_fee_estimates()
-        self.queue_request('mempool.get_fee_histogram', [])
+        await self.queue_request("mempool.get_fee_histogram", [])
         for i in FEE_ETA_TARGETS:
-            self.queue_request('blockchain.estimatefee', [i])
+            await self.queue_request('blockchain.estimatefee', [i])
 
     def get_status_value(self, key):
         if key == 'status':
@@ -336,7 +343,7 @@ class Network(util.DaemonThread):
             value = self.banner
         elif key == 'fee':
             value = self.config.fee_estimates
-        elif key == 'fee_histogram':
+        elif key == "fee_histogram":
             value = self.config.mempool_fees
         elif key == 'updated':
             value = (self.get_local_height(), self.get_server_height())
@@ -378,68 +385,57 @@ class Network(util.DaemonThread):
                     out[host] = { protocol:port }
         return out
 
-    def start_interface(self, server):
+    async def start_interface(self, server):
-        if (not server in self.interfaces and not server in self.connecting):
+        if server not in self.interfaces and server not in self.connecting and not self.stopped:
+            self.connecting[server] = asyncio.Future()
             if server == self.default_server:
                 self.print_error("connecting to %s as new interface" % server)
                 self.set_status('connecting')
-            self.connecting.add(server)
+            iface = self.new_interface(server)
-            c = Connection(server, self.socket_queue, self.config.path)
+            success = await iface.launched
+            # if the interface was launched sucessfully, we save it in interfaces
+            # since that dictionary only stores "good" interfaces
+            if success:
+                assert server not in self.interfaces
+                self.interfaces[server] = iface
+            if not self.connecting[server].done(): self.connecting[server].set_result(True)
+            del self.connecting[server]
 
-    def start_random_interface(self):
+    async def start_random_interface(self):
-        exclude_set = self.disconnected_servers.union(set(self.interfaces))
+        exclude_set = set(self.disconnected_servers.keys()).union(set(self.interfaces.keys()))
         server = pick_random_server(self.get_servers(), self.protocol, exclude_set)
         if server:
-            self.start_interface(server)
+            await self.start_interface(server)
-
-    def start_interfaces(self):
-        self.start_interface(self.default_server)
-        for i in range(self.num_server - 1):
-            self.start_random_interface()
-
-    def set_proxy(self, proxy):
-        self.proxy = proxy
-        # Store these somewhere so we can un-monkey-patch
-        if not hasattr(socket, "_socketobject"):
-            socket._socketobject = socket.socket
-            socket._getaddrinfo = socket.getaddrinfo
-        if proxy:
-            self.print_error('setting proxy', proxy)
-            proxy_mode = proxy_modes.index(proxy["mode"]) + 1
-            socks.setdefaultproxy(proxy_mode,
-                                  proxy["host"],
-                                  int(proxy["port"]),
-                                  # socks.py seems to want either None or a non-empty string
-                                  username=(proxy.get("user", "") or None),
-                                  password=(proxy.get("password", "") or None))
-            socket.socket = socks.socksocket
-            # prevent dns leaks, see http://stackoverflow.com/questions/13184205/dns-over-proxy
-            socket.getaddrinfo = lambda *args: [(socket.AF_INET, socket.SOCK_STREAM, 6, '', (args[0], args[1]))]
-        else:
-            socket.socket = socket._socketobject
-            socket.getaddrinfo = socket._getaddrinfo
 
     def start_network(self, protocol, proxy):
+        self.stopped = False
         assert not self.interface and not self.interfaces
-        assert not self.connecting and self.socket_queue.empty()
+        assert len(self.connecting) == 0
         self.print_error('starting network')
-        self.disconnected_servers = set([])
         self.protocol = protocol
-        self.set_proxy(proxy)
+        self.proxy = proxy
-        self.start_interfaces()
 
-    def stop_network(self):
+    async def stop_network(self):
+        self.stopped = True
         self.print_error("stopping network")
-        for interface in list(self.interfaces.values()):
+        async def stop(interface):
-            self.close_interface(interface)
+            await self.connection_down(interface.server, "stopping network")
-        if self.interface:
+            await interface.boot_job
-            self.close_interface(self.interface)
+        stopped_this_time = set()
-        assert self.interface is None
+        while self.connecting:
-        assert not self.interfaces
+            try:
-        self.connecting = set()
+                await next(iter(self.connecting.values()))
-        # Get a new queue - no old pending connections thanks!
+            except asyncio.CancelledError:
-        self.socket_queue = queue.Queue()
+                # ok since we are shutting down
+                pass
+        while self.interfaces:
+            do_next = next(iter(self.interfaces.values()))
+            stopped_this_time.add(do_next)
+            await stop(do_next)
+        self.process_pending_sends_job.cancel()
+        await self.process_pending_sends_job
 
+    # called from the Qt thread
     def set_parameters(self, host, port, protocol, proxy, auto_connect):
         proxy_str = serialize_proxy(proxy)
         server = serialize_server(host, port, protocol)
@@ -459,25 +455,41 @@ class Network(util.DaemonThread):
             return
         self.auto_connect = auto_connect
         if self.proxy != proxy or self.protocol != protocol:
+            async def job():
+                try:
+                    async with self.restartLock:
                         # Restart the network defaulting to the given server
-            self.stop_network()
+                        await self.stop_network()
+                        self.print_error("STOOOOOOOOOOOOOOOOOOOOOOOOOOPPED")
                         self.default_server = server
+                        self.disconnected_servers = {}
                         self.start_network(protocol, proxy)
+                except BaseException as e:
+                    traceback.print_exc()
+                    self.print_error("exception from restart job")
+            if self.restartLock.locked():
+                self.print_error("NOT RESTARTING, RESTART IN PROGRESS")
+                return
+            asyncio.run_coroutine_threadsafe(job(), self.loop)
         elif self.default_server != server:
-            self.switch_to_interface(server)
+            async def job():
+                await self.switch_to_interface(server)
+            asyncio.run_coroutine_threadsafe(job(), self.loop)
         else:
-            self.switch_lagging_interface()
+            async def job():
+                await self.switch_lagging_interface()
                 self.notify('updated')
+            asyncio.run_coroutine_threadsafe(job(), self.loop)
 
-    def switch_to_random_interface(self):
+    async 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))
+            await self.switch_to_interface(random.choice(servers))
 
-    def switch_lagging_interface(self):
+    async def switch_lagging_interface(self):
         '''If auto_connect and lagging, switch interface'''
         if self.server_is_lagging() and self.auto_connect:
             # switch to one that has the correct header (not height)
@@ -485,9 +497,9 @@ class Network(util.DaemonThread):
             filtered = list(map(lambda x:x[0], filter(lambda x: x[1].tip_header==header, self.interfaces.items())))
             if filtered:
                 choice = random.choice(filtered)
-                self.switch_to_interface(choice)
+                await self.switch_to_interface(choice)
 
-    def switch_to_interface(self, server):
+    async def switch_to_interface(self, server):
         '''Switch to server as our interface.  If no connection exists nor
         being opened, start a thread to connect.  The actual switch will
         happen on receipt of the connection notification.  Do nothing
@@ -495,25 +507,28 @@ class Network(util.DaemonThread):
         self.default_server = server
         if server not in self.interfaces:
             self.interface = None
-            self.start_interface(server)
+            await self.start_interface(server)
             return
         i = self.interfaces[server]
-        if self.interface != i:
+        if self.interface != i and self.num_server != 0:
-            self.print_error("switching to", server)
+            self.print_error("switching to", server, "from", self.interface.server if self.interface else "None")
             # stop any current interface in order to terminate subscriptions
             # fixme: we don't want to close headers sub
             #self.close_interface(self.interface)
             self.interface = i
-            self.send_subscriptions()
+            await self.send_subscriptions()
             self.set_status('connected')
             self.notify('updated')
 
-    def close_interface(self, interface):
+    async def close_interface(self, interface):
-        if interface:
+        self.print_error('closing connection', interface.server)
         if interface.server in self.interfaces:
             self.interfaces.pop(interface.server)
         if interface.server == self.default_server:
             self.interface = None
+        assert not interface.boot_job.cancelled()
+        interface.boot_job.cancel()
+        await interface.boot_job
         interface.close()
 
     def add_recent_server(self, server):
@@ -524,7 +539,7 @@ class Network(util.DaemonThread):
         self.recent_servers = self.recent_servers[0:20]
         self.save_recent_servers()
 
-    def process_response(self, interface, response, callbacks):
+    async def process_response(self, interface, response, callbacks):
         if self.debug:
             self.print_error("<--", response)
         error = response.get('error')
@@ -537,7 +552,7 @@ class Network(util.DaemonThread):
             interface.server_version = result
         elif method == 'blockchain.headers.subscribe':
             if error is None:
-                self.on_notify_header(interface, result)
+                await self.on_notify_header(interface, result)
         elif method == 'server.peers.subscribe':
             if error is None:
                 self.irc_servers = parse_servers(result)
@@ -549,11 +564,11 @@ class Network(util.DaemonThread):
         elif method == 'server.donation_address':
             if error is None:
                 self.donation_address = result
-        elif method == 'mempool.get_fee_histogram':
+        elif method == "mempool.get_fee_histogram":
             if error is None:
-                self.print_error('fee_histogram', result)
+                self.print_error("fee_histogram", result)
                 self.config.mempool_fees = result
-                self.notify('fee_histogram')
+                self.notify("fee_histogram")
         elif method == 'blockchain.estimatefee':
             if error is None and result > 0:
                 i = params[0]
@@ -566,20 +581,25 @@ class Network(util.DaemonThread):
                 self.relay_fee = int(result * COIN)
                 self.print_error("relayfee", self.relay_fee)
         elif method == 'blockchain.block.get_chunk':
-            self.on_get_chunk(interface, response)
+            await self.on_get_chunk(interface, response)
         elif method == 'blockchain.block.get_header':
-            self.on_get_header(interface, response)
+            await self.on_get_header(interface, response)
 
         for callback in callbacks:
+           if asyncio.iscoroutinefunction(callback):
+               if response is None:
+                   print("RESPONSE IS NONE")
+               await callback(response)
+           else:
                callback(response)
 
     def get_index(self, method, params):
         """ hashable index for subscriptions and cache"""
         return str(method) + (':' + str(params[0]) if params else '')
 
-    def process_responses(self, interface):
+    async def process_responses(self, interface):
-        responses = interface.get_responses()
+        while interface.is_running():
-        for request, response in responses:
+            request, response = await interface.get_response()
             if request:
                 method, params, message_id = request
                 k = self.get_index(method, params)
@@ -604,8 +624,8 @@ class Network(util.DaemonThread):
                     self.subscribed_addresses.add(params[0])
             else:
                 if not response:  # Closed remotely / misbehaving
-                    self.connection_down(interface.server)
+                    if interface.is_running(): await self.connection_down(interface.server, "no response in process responses")
-                    break
+                    return
                 # Rewrite response shape to match subscription request response
                 method = response.get('method')
                 params = response.get('params')
@@ -622,7 +642,9 @@ class Network(util.DaemonThread):
             if method.endswith('.subscribe'):
                 self.sub_cache[k] = response
             # Response is now in canonical form
-            self.process_response(interface, response, callbacks)
+            await self.process_response(interface, response, callbacks)
+            await self.run_coroutines()    # Synchronizer and Verifier
+
 
     def addr_to_scripthash(self, addr):
         h = bitcoin.address_to_scripthash(addr)
@@ -651,20 +673,23 @@ class Network(util.DaemonThread):
     def send(self, messages, callback):
         '''Messages is a list of (method, params) tuples'''
         messages = list(messages)
-        with self.lock:
+        async def job(future):
-            self.pending_sends.append((messages, callback))
+            await self.pending_sends.put((messages, callback))
+            if future: future.set_result("put pending send: " + repr(messages))
+        asyncio.run_coroutine_threadsafe(job(None), self.loop)
 
-    def process_pending_sends(self):
+    async def process_pending_sends(self):
         # Requests needs connectivity.  If we don't have an interface,
         # we cannot process them.
         if not self.interface:
+            await asyncio.sleep(1)
             return
 
-        with self.lock:
+        try:
-            sends = self.pending_sends
+            messages, callback = await asyncio.wait_for(self.pending_sends.get(), 1)
-            self.pending_sends = []
+        except TimeoutError:
+            return
 
-        for messages, callback in sends:
         for method, params in messages:
             r = None
             if method.endswith('.subscribe'):
@@ -680,7 +705,7 @@ class Network(util.DaemonThread):
                 util.print_error("cache hit", k)
                 callback(r)
             else:
-                    message_id = self.queue_request(method, params)
+                message_id = await self.queue_request(method, params)
                 self.unanswered_requests[message_id] = method, params, callback
 
     def unsubscribe(self, callback):
@@ -693,88 +718,56 @@ class Network(util.DaemonThread):
                 if callback in v:
                     v.remove(callback)
 
-    def connection_down(self, server):
+    async def connection_down(self, server, reason=None):
         '''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 in self.disconnected_servers:
+            print("already disconnected " + server + " because " + repr(self.disconnected_servers[server]) + ". new reason: " + repr(reason))
+            return
+        self.print_error("connection down", server, reason)
+        self.disconnected_servers[server] = reason
         if server == self.default_server:
             self.set_status('disconnected')
+        if server in self.connecting:
+            await self.connecting[server]
         if server in self.interfaces:
-            self.close_interface(self.interfaces[server])
+            await self.close_interface(self.interfaces[server])
             self.notify('interfaces')
         for b in self.blockchains.values():
             if b.catch_up == server:
                 b.catch_up = None
 
-    def new_interface(self, server, socket):
+    def new_interface(self, server):
         # todo: get tip first, then decide which checkpoint to use.
         self.add_recent_server(server)
-        interface = Interface(server, socket)
+        def interface_exception_handler(exception_future):
+            try:
+                raise exception_future.result()
+            except BaseException as e:
+                asyncio.ensure_future(self.connection_down(server, "error in interface: " + str(e)))
+        interface = Interface(server, self.config.path, self.proxy, lambda: not self.stopped and (server in self.connecting or server in self.interfaces), interface_exception_handler)
+        # this future has its result set when the interface should be considered opened,
+        # e.g. should be moved from connecting to interfaces
+        interface.launched = asyncio.Future()
         interface.blockchain = None
         interface.tip_header = None
         interface.tip = 0
         interface.mode = 'default'
         interface.request = None
-        self.interfaces[server] = interface
+        interface.jobs = None
-        self.queue_request('blockchain.headers.subscribe', [], interface)
+        interface.boot_job = None
-        if server == self.default_server:
+        self.boot_interface(interface)
-            self.switch_to_interface(server)
+        assert server not in self.interfaces
-        #self.notify('interfaces')
+        assert not self.stopped
+        return interface
 
-    def maintain_sockets(self):
+    async def request_chunk(self, interface, idx):
-        '''Socket maintenance.'''
+        interface.print_error("requesting chunk %d" % idx)
-        # Responses to connection attempts?
+        await self.queue_request('blockchain.block.get_chunk', [idx], interface)
-        while not self.socket_queue.empty():
+        interface.request = idx
-            server, socket = self.socket_queue.get()
+        interface.req_time = time.time()
-            if server in self.connecting:
-                self.connecting.remove(server)
-            if socket:
-                self.new_interface(server, socket)
-            else:
-                self.connection_down(server)
 
-        # Send pings and shut down stale interfaces
+    async def on_get_chunk(self, interface, response):
-        # must use copy of values
-        for interface in list(self.interfaces.values()):
-            if interface.has_timed_out():
-                self.connection_down(interface.server)
-            elif interface.ping_required():
-                params = [ELECTRUM_VERSION, PROTOCOL_VERSION]
-                self.queue_request('server.version', params, interface)
-
-        now = time.time()
-        # nodes
-        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:
-                if not self.is_connecting():
-                    self.switch_to_random_interface()
-            else:
-                if self.default_server in self.disconnected_servers:
-                    if now - self.server_retry_time > SERVER_RETRY_INTERVAL:
-                        self.disconnected_servers.remove(self.default_server)
-                        self.server_retry_time = now
-                else:
-                    self.switch_to_interface(self.default_server)
-        else:
-            if self.config.is_fee_estimates_update_required():
-                self.request_fee_estimates()
-
-    def request_chunk(self, interface, index):
-        if index in self.requested_chunks:
-            return
-        interface.print_error("requesting chunk %d" % index)
-        self.requested_chunks.add(index)
-        self.queue_request('blockchain.block.get_chunk', [index], interface)
-
-    def on_get_chunk(self, interface, response):
         '''Handle receiving a chunk of block headers'''
         error = response.get('error')
         result = response.get('result')
@@ -784,43 +777,36 @@ class Network(util.DaemonThread):
             interface.print_error(error or 'bad response')
             return
         index = params[0]
-        # Ignore unsolicited chunks
-        if index not in self.requested_chunks:
-            interface.print_error("received chunk %d (unsolicited)" % index)
-            return
-        else:
-            interface.print_error("received chunk %d" % index)
-        self.requested_chunks.remove(index)
         connect = blockchain.connect_chunk(index, result)
         if not connect:
-            self.connection_down(interface.server)
+            await self.connection_down(interface.server, "could not connect chunk")
             return
         # If not finished, get the next chunk
-        if index >= len(blockchain.checkpoints) and blockchain.height() < interface.tip:
+        if index >= len(blockchain.checkpoints) and interface.blockchain.height() < interface.tip:
-            self.request_chunk(interface, index+1)
+            await self.request_chunk(interface, index+1)
         else:
             interface.mode = 'default'
             interface.print_error('catch up done', blockchain.height())
             blockchain.catch_up = None
         self.notify('updated')
 
-    def request_header(self, interface, height):
+    async def request_header(self, interface, height):
         #interface.print_error("requesting header %d" % height)
-        self.queue_request('blockchain.block.get_header', [height], interface)
+        await self.queue_request('blockchain.block.get_header', [height], interface)
         interface.request = height
         interface.req_time = time.time()
 
-    def on_get_header(self, interface, response):
+    async def on_get_header(self, interface, response):
         '''Handle receiving a single block header'''
         header = response.get('result')
         if not header:
             interface.print_error(response)
-            self.connection_down(interface.server)
+            await self.connection_down(interface.server, "no header in on_get_header")
             return
         height = header.get('block_height')
         if interface.request != height:
             interface.print_error("unsolicited header",interface.request, height)
-            self.connection_down(interface.server)
+            await self.connection_down(interface.server, "unsolicited header")
             return
         chain = blockchain.check_header(header)
         if interface.mode == 'backward':
@@ -840,7 +826,7 @@ class Network(util.DaemonThread):
                 assert next_height >= self.max_checkpoint(), (interface.bad, interface.good)
             else:
                 if height == 0:
-                    self.connection_down(interface.server)
+                    await self.connection_down(interface.server, "height zero in on_get_header")
                     next_height = None
                 else:
                     interface.bad = height
@@ -859,7 +845,7 @@ class Network(util.DaemonThread):
                 next_height = (interface.bad + interface.good) // 2
                 assert next_height >= self.max_checkpoint()
             elif not interface.blockchain.can_connect(interface.bad_header, check_height=False):
-                self.connection_down(interface.server)
+                await self.connection_down(interface.server, "blockchain can't connect")
                 next_height = None
             else:
                 branch = self.blockchains.get(interface.bad)
@@ -918,7 +904,7 @@ class Network(util.DaemonThread):
                 # exit catch_up state
                 interface.print_error('catch up done', interface.blockchain.height())
                 interface.blockchain.catch_up = None
-                self.switch_lagging_interface()
+                await self.switch_lagging_interface()
                 self.notify('updated')
 
         else:
@@ -926,9 +912,9 @@ class Network(util.DaemonThread):
         # If not finished, get the next header
         if next_height:
             if interface.mode == 'catch_up' and interface.tip > next_height + 50:
-                self.request_chunk(interface, next_height // 2016)
+                await self.request_chunk(interface, next_height // 2016)
             else:
-                self.request_header(interface, next_height)
+                await self.request_header(interface, next_height)
         else:
             interface.mode = 'default'
             interface.request = None
@@ -936,34 +922,44 @@ class Network(util.DaemonThread):
         # refresh network dialog
         self.notify('interfaces')
 
-    def maintain_requests(self):
+    def make_send_requests_job(self, interface):
-        for interface in list(self.interfaces.values()):
+        async def job():
-            if interface.request and time.time() - interface.request_time > 20:
-                interface.print_error("blockchain request timed out")
-                self.connection_down(interface.server)
-                continue
-
-    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.num_requests()]
             try:
-            rout, wout, xout = select.select(rin, win, [], 0.1)
+                while True:
-        except socket.error as e:
+                    # this wait_for is necessary since CancelledError
-            # TODO: py3, get code from e
+                    # doesn't seem to get thrown without it
-            code = None
+                    # when using ssl_in_socks
-            if code == errno.EINTR:
+                    try:
-                return
+                        await asyncio.wait_for(interface.send_request(), 1)
-            raise
+                    except TimeoutError:
-        assert not xout
+                        pass
-        for interface in wout:
+            except CancelledError:
-            interface.send_requests()
+                pass
-        for interface in rout:
+            except BaseException as e:
-            self.process_responses(interface)
+                await self.connection_down(interface.server, "exp while send_request: " + str(e))
+
+        return asyncio.ensure_future(job())
+
+    def make_process_responses_job(self, interface):
+        async def job():
+            try:
+                await self.process_responses(interface)
+            except CancelledError:
+                pass
+            except:
+                await self.connection_down(interface.server, "exp in process_responses")
+        return asyncio.ensure_future(job())
+
+    def make_process_pending_sends_job(self):
+        async def job():
+            try:
+                while True:
+                   await self.process_pending_sends()
+            except CancelledError:
+                pass
+            except:
+                await self.connection_down(interface.server, "exp in process_pending_sends_job")
+        return asyncio.ensure_future(job())
 
     def init_headers_file(self):
         b = self.blockchains[0]
@@ -977,23 +973,116 @@ class Network(util.DaemonThread):
         with b.lock:
             b.update_size()
 
-    def run(self):
+    def boot_interface(self, interface):
-        self.init_headers_file()
+        async def job():
-        while self.is_running():
+            try:
-            self.maintain_sockets()
+                interface.jobs = [self.make_send_requests_job(interface)] # we need this job to process the request queued below
-            self.wait_on_sockets()
+                await asyncio.wait_for(self.queue_request('server.version', [ELECTRUM_VERSION, PROTOCOL_VERSION], interface), 10)
-            self.maintain_requests()
+                handshakeResult = await asyncio.wait_for(interface.get_response(), 10)
-            self.run_jobs()    # Synchronizer and Verifier
+                if not interface.is_running():
-            self.process_pending_sends()
+                    self.print_error("WARNING: quitting bootjob instead of handling CancelledError!")
-        self.stop_network()
+                    return
-        self.on_stop()
+                await self.queue_request('blockchain.headers.subscribe', [], interface)
+                if interface.server == self.default_server:
+                    await asyncio.wait_for(self.switch_to_interface(interface.server), 5)
+                interface.jobs += [self.make_process_responses_job(interface)]
+                gathered = asyncio.gather(*interface.jobs)
+                interface.launched.set_result(handshakeResult)
+                while interface.is_running():
+                    try:
+                        await asyncio.wait_for(asyncio.shield(gathered), 1)
+                    except TimeoutError:
+                        pass
+                    if interface.has_timed_out():
+                        self.print_error(interface.server, "timed out")
+                        await self.connection_down(interface.server, "time out in ping_job")
+                        break
+                    elif interface.ping_required():
+                        params = [ELECTRUM_VERSION, PROTOCOL_VERSION]
+                        await self.queue_request('server.version', params, interface)
+                #self.notify('interfaces')
+            except TimeoutError:
+                asyncio.ensure_future(self.connection_down(interface.server, "timeout in boot_interface while getting response"))
+            except CancelledError:
+                pass
+            except:
+                traceback.print_exc()
+            finally:
+                for i in interface.jobs: i.cancel()
+                if not interface.launched.done(): interface.launched.set_result(None)
+        interface.boot_job = asyncio.ensure_future(job())
+        interface.boot_job.server = interface.server
 
-    def on_notify_header(self, interface, header):
+    async def maintain_interfaces(self):
+        if self.stopped:
+            return
+        now = time.time()
+        # nodes
+        if len(self.interfaces) + len(self.connecting) < self.num_server:
+            # ensure future so that servers can be connected to in parallel
+            asyncio.ensure_future(self.start_random_interface())
+            if now - self.nodes_retry_time > NODES_RETRY_INTERVAL:
+                self.print_error('network: retrying connections')
+                self.disconnected_servers = {}
+                self.nodes_retry_time = now
+
+        # main interface
+        if not self.is_connected():
+            if self.auto_connect:
+                if not self.is_connecting():
+                    await self.switch_to_random_interface()
+            else:
+                if self.default_server in self.disconnected_servers:
+                    if now - self.server_retry_time > SERVER_RETRY_INTERVAL:
+                        del self.disconnected_servers[self.default_server]
+                        self.server_retry_time = now
+                else:
+                    await self.switch_to_interface(self.default_server)
+        else:
+            if self.config.is_fee_estimates_update_required():
+                await self.request_fee_estimates()
+
+
+    def run(self):
+        loop = asyncio.new_event_loop()
+        asyncio.set_event_loop(loop) # this does not set the loop on the qt thread
+        self.loop = loop # so we store it in the instance too
+        self.init_headers_file()
+        self.pending_sends = asyncio.Queue()
+        self.restartLock = asyncio.Lock()
+        self.start_network(deserialize_server(self.default_server)[2], deserialize_proxy(self.config.get('proxy')))
+        self.process_pending_sends_job = self.make_process_pending_sends_job()
+        run_future = asyncio.Future()
+        self.run_forever_coroutines()
+        asyncio.ensure_future(self.run_async(run_future))
+
+        loop.run_until_complete(run_future)
+        loop.run_until_complete(self.forever_coroutines_task)
+        run_future.exception()
+        # this would provoke errors of unfinished futures
+        # since we havn't stopped network.
+        # (fast shutdown is more important)
+        #loop.close()
+
+    async def run_async(self, future):
+        try:
+            while self.is_running():
+                await self.maintain_interfaces()
+                self.run_jobs()
+                await asyncio.sleep(1)
+            # not shutting down network if we are going to quit anyway, the OS can clean up
+            #await self.stop_network()
+            self.on_stop()
+            future.set_result("run_async done")
+        except BaseException as e:
+            future.set_exception(e)
+
+    async def on_notify_header(self, interface, header):
         height = header.get('block_height')
         if not height:
             return
         if height < self.max_checkpoint():
-            self.connection_down(interface.server)
+            await self.connection_down(interface.server, "height under max checkpoint in on_notify_header")
             return
         interface.tip_header = header
         interface.tip = height
@@ -1002,7 +1091,7 @@ class Network(util.DaemonThread):
         b = blockchain.check_header(header)
         if b:
             interface.blockchain = b
-            self.switch_lagging_interface()
+            await self.switch_lagging_interface()
             self.notify('updated')
             self.notify('interfaces')
             return
@@ -1010,7 +1099,7 @@ class Network(util.DaemonThread):
         if b:
             interface.blockchain = b
             b.save_header(header)
-            self.switch_lagging_interface()
+            await self.switch_lagging_interface()
             self.notify('updated')
             self.notify('interfaces')
             return
@@ -1019,17 +1108,14 @@ class Network(util.DaemonThread):
             interface.mode = 'backward'
             interface.bad = height
             interface.bad_header = header
-            self.request_header(interface, min(tip +1, height - 1))
+            await self.request_header(interface, min(tip + 1, height - 1))
         else:
             chain = self.blockchains[0]
             if chain.catch_up is None:
                 chain.catch_up = interface
                 interface.mode = 'catch_up'
                 interface.blockchain = chain
-                self.print_error("switching to catchup mode", tip,  self.blockchains)
+                await self.request_header(interface, 0)
-                self.request_header(interface, 0)
-            else:
-                self.print_error("chain already catching up with", chain.catch_up.server)
 
     def blockchain(self):
         if self.interface and self.interface.blockchain is not None:
@@ -1044,6 +1130,7 @@ class Network(util.DaemonThread):
                 out[k] = r
         return out
 
+    # called from the Qt thread
     def follow_chain(self, index):
         blockchain = self.blockchains.get(index)
         if blockchain:
@@ -1051,16 +1138,19 @@ class Network(util.DaemonThread):
             self.config.set_key('blockchain_index', index)
             for i in self.interfaces.values():
                 if i.blockchain == blockchain:
-                    self.switch_to_interface(i.server)
+                    asyncio.run_coroutine_threadsafe(self.switch_to_interface(i.server), self.loop)
                     break
         else:
             raise BaseException('blockchain not found', index)
 
-        if self.interface:
+        # commented out on migration to asyncio. not clear if it
-            server = self.interface.server
+        # relies on the coroutine to be done:
-            host, port, protocol, proxy, auto_connect = self.get_parameters()
+
-            host, port, protocol = server.split(':')
+        #if self.interface:
-            self.set_parameters(host, port, protocol, proxy, auto_connect)
+        #    server = self.interface.server
+        #    host, port, protocol, proxy, auto_connect = self.get_parameters()
+        #    host, port, protocol = server.split(':')
+        #    self.set_parameters(host, port, protocol, proxy, auto_connect)
 
     def get_local_height(self):
         return self.blockchain().height()
@@ -1094,3 +1184,34 @@ class Network(util.DaemonThread):
 
     def max_checkpoint(self):
         return max(0, len(constants.net.CHECKPOINTS) * 2016 - 1)
+
+    async def send_async(self, messages, callback=None):
+        """ if callback is None, it returns the result """
+        chosenCallback = callback
+        if callback is None:
+            queue = asyncio.Queue()
+            chosenCallback = queue.put
+        assert type(messages[0]) is tuple and len(messages[0]) == 2, repr(messages) + " does not contain a pair-tuple in first position"
+        await self.pending_sends.put((messages, chosenCallback))
+        if callback is None:
+            #assert queue.qsize() == 1, "queue does not have a single result, it has length " + str(queue.qsize())
+            return await asyncio.wait_for(queue.get(), 5)
+
+    async def asynchronous_get(self, request):
+        assert type(request) is tuple
+        assert type(request[1]) is list
+        res = await self.send_async([request])
+        try:
+            return res.get("result")
+        except:
+            print("asynchronous_get could not get result from", res)
+            raise BaseException("Could not get result: " + repr(res))
+
+    async def broadcast_async(self, tx):
+        tx_hash = tx.txid()
+        try:
+            return True, await self.asynchronous_get(('blockchain.transaction.broadcast', [str(tx)]))
+        except BaseException as e:
+            traceback.print_exc()
+            print("previous trace was captured and printed in broadcast_async")
+            return False, str(e)

lib/ssl_in_socks.py

@@ -0,0 +1,85 @@
+import traceback
+import ssl
+from asyncio.sslproto import SSLProtocol
+import aiosocks
+import asyncio
+from . import interface
+
+class AppProto(asyncio.Protocol):
+    def __init__(self, receivedQueue, connUpLock):
+        self.buf = bytearray()
+        self.receivedQueue = receivedQueue
+        self.connUpLock = connUpLock
+    def connection_made(self, transport):
+        self.connUpLock.release()
+    def data_received(self, data):
+        self.buf.extend(data)
+        NEWLINE = b"\n"[0]
+        for idx, val in enumerate(self.buf):
+            if NEWLINE == val:
+                asyncio.ensure_future(self.receivedQueue.put(bytes(self.buf[:idx+1])))
+                self.buf = self.buf[idx+1:]
+
+def makeProtocolFactory(receivedQueue, connUpLock, ca_certs):
+    class MySSLProtocol(SSLProtocol):
+        def __init__(self):
+            context = interface.get_ssl_context(\
+                    cert_reqs=ssl.CERT_REQUIRED if ca_certs is not None else ssl.CERT_NONE,\
+                    ca_certs=ca_certs)
+            proto = AppProto(receivedQueue, connUpLock)
+            super().__init__(asyncio.get_event_loop(), proto, context, None)
+    return MySSLProtocol
+
+class ReaderEmulator:
+    def __init__(self, receivedQueue):
+        self.receivedQueue = receivedQueue
+    async def read(self, _bufferSize):
+        return await self.receivedQueue.get()
+
+class WriterEmulator:
+    def __init__(self, transport):
+        self.transport = transport
+    def write(self, data):
+        self.transport.write(data)
+    async def drain(self):
+        pass
+    def close(self):
+        self.transport.close()
+
+async def sslInSocksReaderWriter(socksAddr, socksAuth, host, port, ca_certs):
+    receivedQueue = asyncio.Queue()
+    connUpLock = asyncio.Lock()
+    await connUpLock.acquire()
+    transport, protocol = await aiosocks.create_connection(\
+            makeProtocolFactory(receivedQueue, connUpLock, ca_certs),\
+            proxy=socksAddr,\
+            proxy_auth=socksAuth, dst=(host, port))
+    await connUpLock.acquire()
+    return ReaderEmulator(receivedQueue), WriterEmulator(protocol._app_transport)
+
+if __name__ == "__main__":
+    async def l(fut):
+        try:
+            # aiosocks.Socks4Addr("127.0.0.1", 9050), None, "songbird.bauerj.eu", 50002, None)
+            args = aiosocks.Socks4Addr("127.0.0.1", 9050), None, "electrum.akinbo.org", 51002, None
+            reader, writer = await sslInSocksReaderWriter(*args)
+            writer.write(b'{"id":0,"method":"server.version","args":["3.0.2", "1.1"]}\n')
+            await writer.drain()
+            print(await reader.read(4096))
+            writer.write(b'{"id":0,"method":"server.version","args":["3.0.2", "1.1"]}\n')
+            await writer.drain()
+            print(await reader.read(4096))
+            writer.close()
+            fut.set_result("finished")
+        except BaseException as e:
+            fut.set_exception(e)
+
+    def f():
+        loop = asyncio.get_event_loop()
+        fut = asyncio.Future()
+        asyncio.ensure_future(l(fut))
+        loop.run_until_complete(fut)
+        print(fut.result())
+        loop.close()
+
+    f()

lib/util.py

@@ -29,6 +29,7 @@ import traceback
 import urllib
 import threading
 import hmac
+import asyncio
 
 from .i18n import _
 
@@ -148,6 +149,24 @@ class PrintError(object):
     def print_msg(self, *msg):
         print_msg("[%s]" % self.diagnostic_name(), *msg)
 
+class ForeverCoroutineJob(PrintError):
+    """A job that is run from a thread's main loop.  run() is
+    called from that thread's context.
+    """
+
+    async def run(self, is_running):
+        """Called once from the thread"""
+        pass
+
+class CoroutineJob(PrintError):
+    """A job that is run periodically from a thread's main loop.  run() is
+    called from that thread's context.
+    """
+
+    async def run(self):
+        """Called periodically from the thread"""
+        pass
+
 class ThreadJob(PrintError):
     """A job that is run periodically from a thread's main loop.  run() is
     called from that thread's context.
@@ -192,6 +211,44 @@ class DaemonThread(threading.Thread, PrintError):
         self.running_lock = threading.Lock()
         self.job_lock = threading.Lock()
         self.jobs = []
+        self.coroutines = []
+        self.forever_coroutines_task = None
+
+    def add_coroutines(self, jobs):
+        for i in jobs: assert isinstance(i, CoroutineJob), i.__class__.__name__ + " does not inherit from CoroutineJob"
+        self.coroutines.extend(jobs)
+
+    def set_forever_coroutines(self, jobs):
+        for i in jobs: assert isinstance(i, ForeverCoroutineJob), i.__class__.__name__ + " does not inherit from ForeverCoroutineJob"
+        async def put():
+            await self.forever_coroutines_queue.put(jobs)
+        asyncio.run_coroutine_threadsafe(put(), self.loop)
+
+    def run_forever_coroutines(self):
+        self.forever_coroutines_queue = asyncio.Queue() # making queue here because __init__ is called from non-network thread
+        self.loop = asyncio.get_event_loop()
+        async def getFromQueueAndStart():
+            jobs = []
+            while True:
+                try:
+                    jobs = await asyncio.wait_for(self.forever_coroutines_queue.get(), 1)
+                    break
+                except asyncio.TimeoutError:
+                    if not self.is_running(): break
+                    continue
+            await asyncio.gather(*[i.run(self.is_running) for i in jobs])
+        self.forever_coroutines_task = asyncio.ensure_future(getFromQueueAndStart())
+        return self.forever_coroutines_task
+
+    async def run_coroutines(self):
+        for coroutine in self.coroutines:
+            assert isinstance(coroutine, CoroutineJob)
+            await coroutine.run()
+
+    def remove_coroutines(self, jobs):
+        for i in jobs: assert isinstance(i, CoroutineJob)
+        for job in jobs:
+            self.coroutines.remove(job)
 
     def add_jobs(self, jobs):
         with self.job_lock:
@@ -203,6 +260,7 @@ class DaemonThread(threading.Thread, PrintError):
         # malformed or malicious server responses
         with self.job_lock:
             for job in self.jobs:
+                assert isinstance(job, ThreadJob)
                 try:
                     job.run()
                 except Exception as e: