electrum

commit 219c2a363ae59c33489e3e641653be5fdad02f15
parent 3031f594cb05b538e218dab3edf9e17bce599dd7
Author: SomberNight <somber.night@protonmail.com>
Date:   Sun,  3 Jun 2018 17:17:56 +0200

fix #4401

Diffstat:
M
lib/blockchain.py
 | 
12
+++++++++++-

1 file changed, 11 insertions(+), 1 deletion(-)
diff --git a/lib/blockchain.py b/lib/blockchain.py
@@ -30,6 +30,11 @@ from .bitcoin import *
 
 MAX_TARGET = 0x00000000FFFF0000000000000000000000000000000000000000000000000000
 
+
+class MissingHeader(Exception):
+    pass
+
+
 def serialize_header(res):
     s = int_to_hex(res.get('version'), 4) \
         + rev_hex(res.get('prev_block_hash')) \
@@ -300,6 +305,8 @@ class Blockchain(util.PrintError):
         # new target
         first = self.read_header(index * 2016)
         last = self.read_header(index * 2016 + 2015)
+        if not first or not last:
+            raise MissingHeader()
         bits = last.get('bits')
         target = self.bits_to_target(bits)
         nActualTimespan = last.get('timestamp') - first.get('timestamp')
@@ -343,7 +350,10 @@ class Blockchain(util.PrintError):
             return False
         if prev_hash != header.get('prev_block_hash'):
             return False
-        target = self.get_target(height // 2016 - 1)
+        try:
+            target = self.get_target(height // 2016 - 1)
+        except MissingHeader:
+            return False
         try:
             self.verify_header(header, prev_hash, target)
         except BaseException as e: