network: extend existing connection modes to use a list of servers

The internal names of connection modes are unchanged:
 - auto-connect: behaviour unchanged
 - manual: choose history server within bookmarks. header nodes are not restricted
 - oneserver: choose history server and header nodes within bookmarks

Author: ecdsa

electrum/gui/messages.py

@@ -112,11 +112,12 @@ def to_rtf(msg):
 
 
 MSG_CONNECTMODE_AUTOCONNECT = _('Auto-connect')
-MSG_CONNECTMODE_MANUAL = _('Manual server selection')
-MSG_CONNECTMODE_ONESERVER = _('Connect only to a single server')
+MSG_CONNECTMODE_MANUAL = _('Bookmarked servers')
+MSG_CONNECTMODE_ONESERVER = _('Bookmarked servers (strict)')
 
 MSG_CONNECTMODE_SERVER_HELP = _(
-    "Electrum connects to a unique server in order to receive your transaction history. "
+    "This is the list of servers from wich Electrum may request your transaction history"
+    "Electrum will pick one server from this list, with the longest blockchain. "
     "This server will learn your wallet adddresses."
 )
 MSG_CONNECTMODE_NODES_HELP = _(
@@ -132,12 +133,13 @@ def to_rtf(msg):
 )
 
 MSG_CONNECTMODE_MANUAL_HELP = _(
-    "Electrum will stay with the server you selected. It will warn you if your server is lagging."
+    "Electrum will use the servers you selected in order to request your wallet history. "
+    "It will connect to other nodes for block headers and warn you if your server is lagging."
 )
 
 MSG_CONNECTMODE_ONESERVER_HELP = _(
-    "Electrum will stay with the server you selected, and it will not connect to additional nodes. "
+    "Electrum will use the servers you selected inorder to request your history, and it will not connect to additional nodes. "
     "This will disable fork detection. "
-    "This mode is only intended for connecting to your own fully trusted server. "
-    "Using this option on a public server is a security risk and is discouraged."
+    "This mode is only intended for connecting to a set of fully trusted server. "
+    "Using this option on a single public server is a security risk and is discouraged."
 )

electrum/gui/qt/network_dialog.py

@@ -87,9 +87,9 @@ class ItemType(IntEnum):
         DISCONNECTED_SERVER = 2
         TOPLEVEL = 3
 
-    followServer = pyqtSignal([ServerAddr], arguments=['server'])
     followChain = pyqtSignal([str], arguments=['chain_id'])
     setServer = pyqtSignal([str], arguments=['server'])
+    setBookmark = pyqtSignal([ServerAddr, bool])
 
     def __init__(self, *, network: Network):
         QTreeWidget.__init__(self)
@@ -106,23 +106,18 @@ def create_menu(self, position):
         menu = QMenu()
         if item_type in [self.ItemType.CONNECTED_SERVER, self.ItemType.DISCONNECTED_SERVER]:
             server = item.data(0, self.SERVER_ADDR_ROLE)  # type: ServerAddr
-            if item_type == self.ItemType.CONNECTED_SERVER:
-                def do_follow_server():
-                    self.followServer.emit(server)
-                menu.addAction(read_QIcon("chevron-right.png"), _("Use as server"), do_follow_server)
-            elif item_type == self.ItemType.DISCONNECTED_SERVER:
+
+            if self.network.auto_connect or self.network.is_server_bookmarked(server):
                 def do_set_server():
                     self.setServer.emit(str(server))
                 menu.addAction(read_QIcon("chevron-right.png"), _("Use as server"), do_set_server)
 
-            def set_bookmark(*, add: bool):
-                self.network.set_server_bookmark(server, add=add)
-                self.update()
-
+            def do_set_bookmark(*, add: bool):
+                self.setBookmark.emit(server, add)
             if self.network.is_server_bookmarked(server):
-                menu.addAction(read_QIcon("bookmark_remove.png"), _("Remove from bookmarks"), lambda: set_bookmark(add=False))
+                menu.addAction(read_QIcon("bookmark_remove.png"), _("Remove from bookmarks"), lambda: do_set_bookmark(add=False))
             else:
-                menu.addAction(read_QIcon("bookmark_add.png"), _("Bookmark this server"), lambda: set_bookmark(add=True))
+                menu.addAction(read_QIcon("bookmark_add.png"), _("Bookmark this server"), lambda: do_set_bookmark(add=True))
         elif item_type == self.ItemType.CHAIN:
             chain_id = item.data(0, self.CHAIN_ID_ROLE)
 
@@ -404,7 +399,7 @@ def __init__(self, network: Network, parent=None):
         grid.addWidget(self.connect_combo, 0, 1, 1, 3)
 
         self.server_e = QLineEdit()
-        self.server_e.editingFinished.connect(self.on_server_settings_changed)
+        self.server_e.editingFinished.connect(self.on_server_edited)
         grid.addWidget(QLabel(_('Server') + ':'), 1, 0)
         grid.addWidget(self.server_e, 1, 1, 1, 3)
         grid.addWidget(HelpButton(messages.MSG_CONNECTMODE_SERVER_HELP), 1, 4)
@@ -430,13 +425,10 @@ def __init__(self, network: Network, parent=None):
         self.layout().addLayout(grid)
 
         self.nodes_list_widget = NodesListWidget(network=self.network)
-        self.nodes_list_widget.followServer.connect(self.follow_server)
         self.nodes_list_widget.followChain.connect(self.follow_branch)
+        self.nodes_list_widget.setBookmark.connect(self.set_bookmark)
 
-        def do_set_server(server):
-            self.server_e.setText(server)
-            self.set_server()
-        self.nodes_list_widget.setServer.connect(do_set_server)
+        self.nodes_list_widget.setServer.connect(self.set_server)
 
         self.layout().addWidget(self.nodes_list_widget)
         self.nodes_list_widget.update()
@@ -462,10 +454,9 @@ def on_server_settings_changed(self):
         if not self.network._was_started:
             self.update()
             return
-        server = self.server_e.text().strip()
         net_params = self.network.get_parameters()
-        if server != net_params.server or self.is_auto_connect() != net_params.auto_connect or self.is_one_server() != net_params.oneserver:
-            self.set_server()
+        if self.is_auto_connect() != net_params.auto_connect or self.is_one_server() != net_params.oneserver:
+            self.set_params()
 
     def update(self):
         self.server_e.setEnabled(self.config.cv.NETWORK_SERVER.is_modifiable() and not self.is_auto_connect())
@@ -493,15 +484,19 @@ def update(self):
                     msg += _('Your server is on branch {0} ({1} blocks)').format(name, chain.get_branch_size())
         self.split_label.setText(msg)
 
+    def update_server_edit(self):
+        self.server_e.setText(str(self.network.default_server) if self.network.default_server else '')
+
+    @qt_event_listener
+    def on_event_default_server_changed(self):
+        self.update_server_edit()
+
     def update_from_config(self):
         auto_connect = self.config.NETWORK_AUTO_CONNECT
         one_server = self.config.NETWORK_ONESERVER
         v = ConnectMode.AUTOCONNECT if auto_connect else ConnectMode.ONESERVER if one_server else ConnectMode.MANUAL
         self.connect_combo.setCurrentIndex(v)
-
-        server = self.config.NETWORK_SERVER
-        self.server_e.setText(server)
-
+        self.update_server_edit()
         self.server_e.setEnabled(self.config.cv.NETWORK_SERVER.is_modifiable() and not auto_connect)
         self.nodes_list_widget.setEnabled(self.config.cv.NETWORK_SERVER.is_modifiable())
 
@@ -514,16 +509,41 @@ def follow_server(self, server: ServerAddr):
         self.network.run_from_another_thread(self.network.follow_chain_given_server(server))
         self.update()
 
-    def set_server(self):
-        net_params = self.network.get_parameters()
+    def on_server_edited(self):
+        try:
+            server = ServerAddr.from_str_with_inference(self.server_e.text())
+            if not server:
+                raise Exception("failed to parse server")
+        except Exception as e:
+            print(f'exception {e}')
+            self.server_e.setText('')
+            return
+        #if self.parent.question('add bookmark?'):
+        # ask whether we want to bookmark it
+        print('adding bookmark')
+        self.set_bookmark(server, add=True)
+        self.set_server(str(server))
+
+    def set_bookmark(self, server, add: bool):
+        self.network.set_server_bookmark(server, add=add)
+        self.nodes_list_widget.update()
+        self.update()
+
+    def set_server(self, server_str: str):
+        # if autoconnect, simply follow that server
+        # in other modes too; the server must be bookmarked
         try:
-            server = ServerAddr.from_str_with_inference(str(self.server_e.text()))
+            server = ServerAddr.from_str_with_inference(server_str)
             if not server:
                 raise Exception("failed to parse server")
         except Exception:
             return
+        self.network.run_from_another_thread(self.network.switch_to_interface(server))
+        self.update()
+
+    def set_params(self):
+        net_params = self.network.get_parameters()
         net_params = net_params._replace(
-            server=server,
             auto_connect=self.is_auto_connect(),
             oneserver=self.is_one_server(),
         )