add checkpoint dialog to the kivy gui

gui/kivy/uix/dialogs/checkpoint_dialog.py

@@ -0,0 +1,86 @@
+from kivy.app import App
+from kivy.factory import Factory
+from kivy.properties import ObjectProperty
+from kivy.lang import Builder
+
+
+
+Builder.load_string('''
+#:import _ electrum_gui.kivy.i18n._
+
+<CheckpointDialog@Popup>
+    id: popup
+    cp_height: 0
+    cp_value: ''
+    title: _('Checkpoint')
+    size_hint: 0.8, 0.8
+    pos_hint: {'top':0.9}
+    BoxLayout:
+        orientation: 'vertical'
+        Label:
+            id: description
+            text: 'In the event of a blockchain fork, a checkpoint can be used to ensure that you are on the correct blockchain.'
+            halign: 'left'
+            text_size: self.width, None
+            size: self.texture_size
+        BoxLayout:
+            orientation: 'horizontal'
+            size_hint: 1, 0.2
+            Label:
+                text: _('Height')
+                height: '48dp'
+            TextInput:
+                id: height_input
+                text: '%d'%root.cp_height
+                on_focus: root.on_height_str()
+        TopLabel:
+            text: _('Block hash') + ':'
+        TxHashLabel:
+            data: root.cp_value
+        Label:
+            text: 'Edit the height to fetch a checkpoint from your main server, and check its value from independent sources.'
+            halign: 'left'
+            text_size: self.width, None
+            size: self.texture_size
+        Widget:
+            size_hint: 1, 0.3
+        BoxLayout:
+            orientation: 'horizontal'
+            size_hint: 1, 0.2
+            Button:
+                text: _('Cancel')
+                size_hint: 0.5, None
+                height: '48dp'
+                on_release: popup.dismiss()
+            Button:
+                text: _('OK')
+                size_hint: 0.5, None
+                height: '48dp'
+                on_release:
+                    root.callback(root.cp_height, root.cp_value)
+                    popup.dismiss()
+''')
+
+class CheckpointDialog(Factory.Popup):
+    def __init__(self, network, callback):
+        Factory.Popup.__init__(self)
+        self.network = network
+        self.cp_height, self.cp_value = self.network.blockchain.get_checkpoint()
+        self.callback = callback
+
+    def on_height_str(self):
+        try:
+            new_height = int(self.ids.height_input.text)
+        except:
+            new_height = 0
+        if new_height == self.cp_height:
+            return
+        try:
+            header = self.network.synchronous_get(('blockchain.block.get_header', [new_height]), 5)
+            new_value = self.network.blockchain.hash_header(header)
+        except BaseException as e:
+            self.network.print_error(str(e))
+            new_value = ''
+        if new_value:
+            self.cp_height = new_height
+            self.cp_value = new_value

gui/kivy/uix/dialogs/settings.py

@@ -113,6 +113,12 @@ Builder.load_string('''
                     title: _('Coin selection') + ': ' + self.status
                     description: "Coin selection method"
                     action: partial(root.coinselect_dialog, self)
+                CardSeparator
+                SettingsItem:
+                    status: root.checkpoint_status()
+                    title: _('Checkpoint') + ': ' + self.status
+                    description: _("Configure blockchain checkpoint")
+                    action: partial(root.checkpoint_dialog, self)
 ''')
 
 
@@ -134,6 +140,7 @@ class SettingsDialog(Factory.Popup):
         self._language_dialog = None
         self._unit_dialog = None
         self._coinselect_dialog = None
+        self._checkpoint_dialog = None
 
     def update(self):
         self.wallet = self.app.wallet
@@ -177,6 +184,21 @@ class SettingsDialog(Factory.Popup):
             self._coinselect_dialog = ChoiceDialog(_('Coin selection'), choosers, chooser_name, cb)
         self._coinselect_dialog.open()
 
+    def checkpoint_status(self):
+        height, value = self.app.network.blockchain.get_checkpoint()
+        return "Block %d"% height if height else _("Genesis block")
+
+    def checkpoint_dialog(self, item, dt):
+        from checkpoint_dialog import CheckpointDialog
+        if self._checkpoint_dialog is None:
+            def callback(height, value):
+                if value:
+                    self.app.network.blockchain.set_checkpoint(height, value)
+                    item.status = self.checkpoint_status()
+
+            self._checkpoint_dialog = CheckpointDialog(self.app.network, callback)
+        self._checkpoint_dialog.open()
+
     def network_dialog(self, item, dt):
         if self._network_dialog is None:
             server, port, protocol, proxy, auto_connect = self.app.network.get_parameters()

gui/qt/network_dialog.py

@@ -192,8 +192,7 @@ class NetworkChoiceLayout(object):
         n = len(network.get_interfaces())
         status = _("Connected to %d nodes.")%n if n else _("Not connected")
         height_str = "%d "%(network.get_local_height()) + _("blocks")
-        self.checkpoint_height = self.config.get('checkpoint_height', 0)
-        self.checkpoint_value = self.config.get('checkpoint_value', bitcoin.GENESIS)
+        self.checkpoint_height, self.checkpoint_value = network.blockchain.get_checkpoint()
         self.cph_label = QLabel(_('Height'))
         self.cph = QLineEdit("%d"%self.checkpoint_height)
         self.cph.setFixedWidth(80)
@@ -337,8 +336,7 @@ class NetworkChoiceLayout(object):
         auto_connect = self.autoconnect_cb.isChecked()
 
         self.network.set_parameters(host, port, protocol, proxy, auto_connect)
-        self.config.set_key('checkpoint_height', self.checkpoint_height)
-        self.config.set_key('checkpoint_value', self.checkpoint_value)
+        self.network.blockchain.set_checkpoint(self.checkpoint_height, self.checkpoint_value)
 
     def suggest_proxy(self, found_proxy):
         self.tor_proxy = found_proxy

lib/blockchain.py

@@ -37,8 +37,7 @@ class Blockchain(util.PrintError):
     def __init__(self, config, network):
         self.config = config
         self.network = network
-        self.checkpoint_height = self.config.get('checkpoint_height', 0)
-        self.checkpoint_hash = self.config.get('checkpoint_value', bitcoin.GENESIS)
+        self.checkpoint_height, self.checkpoint_hash = self.get_checkpoint()
         self.check_truncate_headers()
         self.set_local_height()
 
@@ -189,6 +188,7 @@ class Blockchain(util.PrintError):
             return
         if self.hash_header(checkpoint) == self.checkpoint_hash:
             return
+        self.print_error('checkpoint mismatch:', self.hash_header(checkpoint), self.checkpoint_hash)
         self.print_error('Truncating headers file at height %d'%self.checkpoint_height)
         name = self.path()
         f = open(name, 'rb+')
@@ -274,3 +274,15 @@ class Blockchain(util.PrintError):
         except BaseException as e:
             self.print_error('verify_chunk failed', str(e))
             return idx - 1
+
+    def get_checkpoint(self):
+        height = self.config.get('checkpoint_height', 0)
+        value = self.config.get('checkpoint_value', bitcoin.GENESIS)
+        return (height, value)
+
+    def set_checkpoint(self, height, value):
+        self.checkpoint_height = height
+        self.checkpoint_hash = value
+        self.config.set_key('checkpoint_height', height)
+        self.config.set_key('checkpoint_value', value)
+        self.check_truncate_headers()