fix #3955: fix interference between verifier and catch_up

lib/blockchain.py

@@ -181,7 +181,8 @@ class Blockchain(util.PrintError):
         if d < 0:
             chunk = chunk[-d:]
             d = 0
-        self.write(chunk, d, index > len(self.checkpoints))
+        truncate = index >= len(self.checkpoints)
+        self.write(chunk, d, truncate)
         self.swap_with_parent()
 
     def swap_with_parent(self):
@@ -338,7 +339,7 @@ class Blockchain(util.PrintError):
             self.save_chunk(idx, data)
             return True
         except BaseException as e:
-            self.print_error('verify_chunk failed', str(e))
+            self.print_error('verify_chunk %d failed'%idx, str(e))
             return False
 
     def get_checkpoints(self):

lib/network.py

@@ -777,6 +777,7 @@ class Network(util.DaemonThread):
         error = response.get('error')
         result = response.get('result')
         params = response.get('params')
+        blockchain = interface.blockchain
         if result is None or params is None or error is not None:
             interface.print_error(error or 'bad response')
             return
@@ -785,17 +786,17 @@ class Network(util.DaemonThread):
         if index not in self.requested_chunks:
             return
         self.requested_chunks.remove(index)
-        connect = interface.blockchain.connect_chunk(index, result)
+        connect = blockchain.connect_chunk(index, result)
         if not connect:
             self.connection_down(interface.server)
             return
         # If not finished, get the next chunk
-        if interface.blockchain.height() < interface.tip:
+        if index >= len(blockchain.checkpoints) and blockchain.height() < interface.tip:
             self.request_chunk(interface, index+1)
         else:
             interface.mode = 'default'
-            interface.print_error('catch up done', interface.blockchain.height())
-            interface.blockchain.catch_up = None
+            interface.print_error('catch up done', blockchain.height())
+            blockchain.catch_up = None
         self.notify('updated')
 
     def request_header(self, interface, height):

lib/verifier.py

@@ -36,15 +36,19 @@ class SPV(ThreadJob):
         self.merkle_roots = {}
 
     def run(self):
+        if not self.network.interface:
+            return
         lh = self.network.get_local_height()
         unverified = self.wallet.get_unverified_txs()
+        blockchain = self.network.blockchain()
         for tx_hash, tx_height in unverified.items():
             # do not request merkle branch before headers are available
             if (tx_height > 0) and (tx_height <= lh):
-                header = self.network.blockchain().read_header(tx_height)
-                if header is None and self.network.interface:
+                header = blockchain.read_header(tx_height)
+                if header is None:
                     index = tx_height // 2016
-                    self.network.request_chunk(self.network.interface, index)
+                    if index < len(blockchain.checkpoints):
+                        self.network.request_chunk(self.network.interface, index)
                 else:
                     if tx_hash not in self.merkle_roots:
                         request = ('blockchain.transaction.get_merkle',