Make linearize scripts Python 3-compatible.

contrib/linearize/linearize-hashes.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 #
 # linearize-hashes.py:  List blocks in a linear, no-fork version of the chain.
 #
@@ -8,11 +8,14 @@
 #
 
 from __future__ import print_function
+try: # Python 3
+    import http.client as httplib
+except ImportError: # Python 2
+    import httplib
 import json
 import struct
 import re
 import base64
-import httplib
 import sys
 
 settings = {}
@@ -20,26 +23,32 @@ settings = {}
 ##### Switch endian-ness #####
 def hex_switchEndian(s):
 	""" Switches the endianness of a hex string (in pairs of hex chars) """
-	pairList = [s[i]+s[i+1] for i in range(0,len(s),2)]
-	return ''.join(pairList[::-1])
+	pairList = [s[i:i+2].encode() for i in range(0, len(s), 2)]
+	return b''.join(pairList[::-1]).decode()
 
 class BitcoinRPC:
 	def __init__(self, host, port, username, password):
 		authpair = "%s:%s" % (username, password)
-		self.authhdr = "Basic %s" % (base64.b64encode(authpair))
-		self.conn = httplib.HTTPConnection(host, port, False, 30)
+		authpair = authpair.encode('utf-8')
+		self.authhdr = b"Basic " + base64.b64encode(authpair)
+		self.conn = httplib.HTTPConnection(host, port=port, timeout=30)
 
 	def execute(self, obj):
-		self.conn.request('POST', '/', json.dumps(obj),
-			{ 'Authorization' : self.authhdr,
-			  'Content-type' : 'application/json' })
+		try:
+			self.conn.request('POST', '/', json.dumps(obj),
+				{ 'Authorization' : self.authhdr,
+				  'Content-type' : 'application/json' })
+		except ConnectionRefusedError:
+			print('RPC connection refused. Check RPC settings and the server status.',
+			      file=sys.stderr)
+			return None
 
 		resp = self.conn.getresponse()
 		if resp is None:
 			print("JSON-RPC: no response", file=sys.stderr)
 			return None
 
-		body = resp.read()
+		body = resp.read().decode('utf-8')
 		resp_obj = json.loads(body)
 		return resp_obj
 
@@ -70,6 +79,9 @@ def get_block_hashes(settings, max_blocks_per_call=10000):
 			batch.append(rpc.build_request(x, 'getblockhash', [height + x]))
 
 		reply = rpc.execute(batch)
+		if reply is None:
+			print('Cannot continue. Program will halt.')
+			return None
 
 		for x,resp_obj in enumerate(reply):
 			if rpc.response_is_error(resp_obj):