Merge bitcoin/bitcoin#24374: contrib: refactor: simplify linearize scripts

254a63e contrib: refactor: replace `hex_switchEndian` in linearize scripts (Sebastian Falbesoner)
3f863cf contrib: refactor: simplify block header string routine in linearize-data.py (Sebastian Falbesoner)

Pull request description:

  This PR simplifies the linearization scripts `linearize-data.py` and `linearize-hashes.py` by replacing overly complicated cruft (block header hash string calculation, hex string reverse) with means of the Python3 standard library.

ACKs for top commit:
  laanwj:
    Code review ACK 254a63e

Tree-SHA512: 4a0e20e63bd11f23a190480b22dbc2f2a3070e2a4f3a01b8797f99bb5fc830185e91e6712c8ae97562f9a24a98aa4f19d52f02a3f5fcbe4c578ee88a41382d1d

Author: laanwj

contrib/linearize/linearize-data.py

@@ -20,49 +20,9 @@
 
 settings = {}
 
-def hex_switchEndian(s):
-    """ Switches the endianness of a hex string (in pairs of hex chars) """
-    pairList = [s[i:i+2].encode() for i in range(0, len(s), 2)]
-    return b''.join(pairList[::-1]).decode()
-
-def uint32(x):
-    return x & 0xffffffff
-
-def bytereverse(x):
-    return uint32(( ((x) << 24) | (((x) << 8) & 0x00ff0000) |
-               (((x) >> 8) & 0x0000ff00) | ((x) >> 24) ))
-
-def bufreverse(in_buf):
-    out_words = []
-    for i in range(0, len(in_buf), 4):
-        word = struct.unpack('@I', in_buf[i:i+4])[0]
-        out_words.append(struct.pack('@I', bytereverse(word)))
-    return b''.join(out_words)
-
-def wordreverse(in_buf):
-    out_words = []
-    for i in range(0, len(in_buf), 4):
-        out_words.append(in_buf[i:i+4])
-    out_words.reverse()
-    return b''.join(out_words)
-
-def calc_hdr_hash(blk_hdr):
-    hash1 = hashlib.sha256()
-    hash1.update(blk_hdr)
-    hash1_o = hash1.digest()
-
-    hash2 = hashlib.sha256()
-    hash2.update(hash1_o)
-    hash2_o = hash2.digest()
-
-    return hash2_o
-
 def calc_hash_str(blk_hdr):
-    hash = calc_hdr_hash(blk_hdr)
-    hash = bufreverse(hash)
-    hash = wordreverse(hash)
-    hash_str = hash.hex()
-    return hash_str
+    blk_hdr_hash = hashlib.sha256(hashlib.sha256(blk_hdr).digest()).digest()
+    return blk_hdr_hash[::-1].hex()
 
 def get_blk_dt(blk_hdr):
     members = struct.unpack("<I", blk_hdr[68:68+4])
@@ -78,7 +38,7 @@ def get_block_hashes(settings):
     for line in f:
         line = line.rstrip()
         if settings['rev_hash_bytes'] == 'true':
-            line = hex_switchEndian(line)
+            line = bytes.fromhex(line)[::-1].hex()
         blkindex.append(line)
 
     print("Read " + str(len(blkindex)) + " hashes")

contrib/linearize/linearize-hashes.py

@@ -17,11 +17,6 @@
 
 settings = {}
 
-def hex_switchEndian(s):
-    """ Switches the endianness of a hex string (in pairs of hex chars) """
-    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)
@@ -85,7 +80,7 @@ def get_block_hashes(settings, max_blocks_per_call=10000):
                 sys.exit(1)
             assert(resp_obj['id'] == x) # assume replies are in-sequence
             if settings['rev_hash_bytes'] == 'true':
-                resp_obj['result'] = hex_switchEndian(resp_obj['result'])
+                resp_obj['result'] = bytes.fromhex(resp_obj['result'])[::-1].hex()
             print(resp_obj['result'])
 
         height += num_blocks