test: Rename early key response test and move random_bitflip to util

Early key response test is a special kind of test which requires
modified v2 handshake functions. More such tests can be added
where v2 handshake functions send incorrect garbage terminator,
excess garbage bytes etc.. Hence, rename p2p_v2_earlykey.py to a
general test file name - p2p_v2_misbehaving.py.

random_bitflip function (used in signature tests prior to this
commit) can be used in p2p_v2_misbehaving test to generate wrong
garbage terminator, wrong garbage bytes etc..
So, move the function to util.

1 files changed, 7 insertions, 0 deletions

diff --git a/test/functional/test_framework/util.py b/test/functional/test_framework/util.py
index b4b05b1597..53f4a8ee4d 100644
--- a/test/functional/test_framework/util.py
+++ b/test/functional/test_framework/util.py
@@ -14,6 +14,7 @@ import logging
 import os
 import pathlib
 import platform
+import random
 import re
 import time
 
@@ -230,6 +231,12 @@ def ceildiv(a, b):
     return -(-a // b)
 
 
+def random_bitflip(data):
+    data = list(data)
+    data[random.randrange(len(data))] ^= (1 << (random.randrange(8)))
+    return bytes(data)
+
+
 def get_fee(tx_size, feerate_btc_kvb):
     """Calculate the fee in BTC given a feerate is BTC/kvB. Reflects CFeeRate::GetFee"""
     feerate_sat_kvb = int(feerate_btc_kvb * Decimal(1e8)) # Fee in sat/kvb as an int to avoid float precision errors