Add getblockheader RPC call

Author: saltduck

bitcoin/rpc.py

@@ -43,7 +43,7 @@
     import urlparse
 
 import bitcoin
-from bitcoin.core import COIN, lx, b2lx, CBlock, CTransaction, COutPoint, CTxOut
+from bitcoin.core import COIN, lx, b2lx, CBlock, CBlockHeader, CTransaction, COutPoint, CTxOut
 from bitcoin.core.script import CScript
 from bitcoin.wallet import CBitcoinAddress, CBitcoinSecret
 
@@ -350,6 +350,24 @@ def getbestblockhash(self):
         """Return hash of best (tip) block in longest block chain."""
         return lx(self._call('getbestblockhash'))
 
+    def getblockheader(self, block_hash):
+        """Get block header <block_hash>
+
+        Raises IndexError if block_hash is not valid.
+        """
+        try:
+            block_hash = b2lx(block_hash)
+        except TypeError:
+            raise TypeError('%s.getblockheader(): block_hash must be bytes; got %r instance' %
+                    (self.__class__.__name__, block_hash.__class__))
+        try:
+            r = self._call('getblockheader', block_hash, False)
+        except JSONRPCError as ex:
+            raise IndexError('%s.getblockheader(): %s (%d)' %
+                    (self.__class__.__name__, ex.error['message'], ex.error['code']))
+        return CBlockHeader.deserialize(unhexlify(r))
+
+
     def getblock(self, block_hash):
         """Get block <block_hash>