test: Disable automatic connections by default

This prevents the node from trying to connect to random IPs on the internet
while running the functional tests. Exceptions are added when required for
the test to pass.

test/functional/test_framework/util.py

@@ -338,17 +338,17 @@ def rpc_url(datadir, i, chain, rpchost):
 ################
 
 
-def initialize_datadir(dirname, n, chain):
+def initialize_datadir(dirname, n, chain, disable_autoconnect=True):
     datadir = get_datadir_path(dirname, n)
     if not os.path.isdir(datadir):
         os.makedirs(datadir)
-    write_config(os.path.join(datadir, "bitcoin.conf"), n=n, chain=chain)
+    write_config(os.path.join(datadir, "bitcoin.conf"), n=n, chain=chain, disable_autoconnect=disable_autoconnect)
     os.makedirs(os.path.join(datadir, 'stderr'), exist_ok=True)
     os.makedirs(os.path.join(datadir, 'stdout'), exist_ok=True)
     return datadir
 
 
-def write_config(config_path, *, n, chain, extra_config=""):
+def write_config(config_path, *, n, chain, extra_config="", disable_autoconnect=True):
     # Translate chain subdirectory name to config name
     if chain == 'testnet3':
         chain_name_conf_arg = 'testnet'
@@ -376,6 +376,8 @@ def write_config(config_path, *, n, chain, extra_config=""):
         f.write("shrinkdebugfile=0\n")
         # To improve SQLite wallet performance so that the tests don't timeout, use -unsafesqlitesync
         f.write("unsafesqlitesync=1\n")
+        if disable_autoconnect:
+            f.write("connect=0\n")
         f.write(extra_config)