Namecoin / AuxPoW: Support deserializing headers with trailing data; …

…support verifying chunks of variable-length headers.

lib/auxpow.py

@@ -59,7 +59,7 @@ def auxpow_active(base_header):
 
     return height_allows_auxpow and version_allows_auxpow
 
-def deserialize_auxpow_header(base_header, s):
+def deserialize_auxpow_header(base_header, s, expect_trailing_data=False):
     auxpow_header = {}
 
     # Chain ID is the top 16 bits of the 32-bit version.
@@ -81,14 +81,19 @@ def deserialize_auxpow_header(base_header, s):
     auxpow_header['coinbase_merkle_branch'], auxpow_header['coinbase_merkle_index'], s = deserialize_merkle_branch(s)
     auxpow_header['chain_merkle_branch'], auxpow_header['chain_merkle_index'], s = deserialize_merkle_branch(s)
 
-    # Finally there's the parent header.  Deserialize it.
-    # deserialize_header will error if there's any trailing data,
-    # so we don't need to check it here.
-    auxpow_header['parent_header'] = electrum_nmc.blockchain.deserialize_header(s, 1)
+    # Finally there's the parent header.  Deserialize it, along with any
+    # trailing data if requested.
+    if expect_trailing_data:
+        auxpow_header['parent_header'], trailing_data = electrum_nmc.blockchain.deserialize_header(s, 1, expect_trailing_data=expect_trailing_data)
+    else:
+        auxpow_header['parent_header'] = electrum_nmc.blockchain.deserialize_header(s, 1, expect_trailing_data=expect_trailing_data)
     # The parent block header doesn't have any block height,
     # so delete that field.  (We used 1 as a dummy value above.)
     del auxpow_header['parent_header']['block_height']
 
+    if expect_trailing_data:
+        return auxpow_header, trailing_data
+
     return auxpow_header
 
 # Copied from merkle_branch_from_string in https://github.com/electrumalt/electrum-doge/blob/f74312822a14f59aa8d50186baff74cade449ccd/lib/blockchain.py#L622

lib/blockchain.py

@@ -46,7 +46,7 @@ def serialize_header(res):
         + int_to_hex(int(res.get('nonce')), 4)
     return s
 
-def deserialize_header(s, height):
+def deserialize_header(s, height, expect_trailing_data=False):
     if not s:
         raise Exception('Invalid header: {}'.format(s))
     if len(s) < 80:
@@ -62,9 +62,18 @@ def deserialize_header(s, height):
     h['block_height'] = height
 
     if auxpow.auxpow_active(h):
-        h['auxpow'] = auxpow.deserialize_auxpow_header(h, s[80:])
-    elif len(s) != 80:
-        raise Exception('Invalid header length: {}'.format(len(s)))
+        if expect_trailing_data:
+            h['auxpow'], trailing_data = auxpow.deserialize_auxpow_header(h, s[80:], expect_trailing_data=True)
+        else:
+            h['auxpow'] = auxpow.deserialize_auxpow_header(h, s[80:])
+    else:
+        if expect_trailing_data:
+            trailing_data = s[80:]
+        elif len(s) != 80:
+            raise Exception('Invalid header length: {}'.format(len(s)))
+
+    if expect_trailing_data:
+        return h, trailing_data
 
     return h
 
@@ -178,14 +187,15 @@ def verify_header(self, header, prev_hash, target):
             raise Exception("insufficient proof of work: %s vs target %s" % (int('0x' + _hash, 16), target))
 
     def verify_chunk(self, index, data):
-        num = len(data) // 80
+        trailing_data = data
         prev_hash = self.get_hash(index * 2016 - 1)
         target = self.get_target(index-1)
-        for i in range(num):
-            raw_header = data[i*80:(i+1) * 80]
-            header = deserialize_header(raw_header, index*2016 + i)
+        i = 0
+        while len(trailing_data) > 0:
+            header, trailing_data = deserialize_header(trailing_data, index*2016 + i, expect_trailing_data=True)
             self.verify_header(header, prev_hash, target)
             prev_hash = hash_header(header)
+            i = i + 1
 
     def path(self):
         d = util.get_headers_dir(self.config)