Merge #15990: Add tests and documentation for blocksonly

fa8ced32a6 doc: Mention blocksonly in reduce-traffic.md, unhide option (MarcoFalke)
fa320de79f test: Add test for p2p_blocksonly (MarcoFalke)
fa3872e7b4 test: Format predicate source as multiline on error (MarcoFalke)
fa1dce7329 net: Rename ::fRelayTxes to ::g_relay_txes (MarcoFalke)

Pull request description:

  This is de-facto no longer hidden

ACKs for commit fa8ced:
  jamesob:
    utACK fa8ced32a6

Tree-SHA512: 474fbdee6cbd035ed9068a066b6056c1f909ec7520be0417820fcd1672ab3069b53f55c5147968978d9258fd3a3933fe1a9ef8e4f6e14fb6ebbd79701a0a1245

test/functional/p2p_blocksonly.py

@@ -0,0 +1,58 @@
+#!/usr/bin/env python3
+# Copyright (c) 2019 The Bitcoin Core developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
+"""Test p2p blocksonly"""
+
+from test_framework.messages import msg_tx, CTransaction, FromHex
+from test_framework.mininode import P2PInterface
+from test_framework.test_framework import BitcoinTestFramework
+from test_framework.util import assert_equal
+
+
+class P2PBlocksOnly(BitcoinTestFramework):
+    def set_test_params(self):
+        self.setup_clean_chain = False
+        self.num_nodes = 1
+        self.extra_args = [["-blocksonly"]]
+
+    def run_test(self):
+        self.nodes[0].add_p2p_connection(P2PInterface())
+
+        self.log.info('Check that txs from p2p are rejected')
+        prevtx = self.nodes[0].getblock(self.nodes[0].getblockhash(1), 2)['tx'][0]
+        rawtx = self.nodes[0].createrawtransaction(
+            inputs=[{
+                'txid': prevtx['txid'],
+                'vout': 0
+            }],
+            outputs=[{
+                self.nodes[0].get_deterministic_priv_key().address: 50 - 0.00125
+            }],
+        )
+        sigtx = self.nodes[0].signrawtransactionwithkey(
+            hexstring=rawtx,
+            privkeys=[self.nodes[0].get_deterministic_priv_key().key],
+            prevtxs=[{
+                'txid': prevtx['txid'],
+                'vout': 0,
+                'scriptPubKey': prevtx['vout'][0]['scriptPubKey']['hex'],
+            }],
+        )['hex']
+        assert_equal(self.nodes[0].getnetworkinfo()['localrelay'], False)
+        with self.nodes[0].assert_debug_log(['transaction sent in violation of protocol peer=0']):
+            self.nodes[0].p2p.send_message(msg_tx(FromHex(CTransaction(), sigtx)))
+            self.nodes[0].p2p.sync_with_ping()
+            assert_equal(self.nodes[0].getmempoolinfo()['size'], 0)
+
+        self.log.info('Check that txs from rpc are not rejected and relayed to other peers')
+        assert_equal(self.nodes[0].getpeerinfo()[0]['relaytxes'], True)
+        txid = self.nodes[0].testmempoolaccept([sigtx])[0]['txid']
+        with self.nodes[0].assert_debug_log(['received getdata for: tx {} peer=0'.format(txid)]):
+            self.nodes[0].sendrawtransaction(sigtx)
+            self.nodes[0].p2p.wait_for_tx(txid)
+            assert_equal(self.nodes[0].getmempoolinfo()['size'], 1)
+
+
+if __name__ == '__main__':
+    P2PBlocksOnly().main()

test/functional/test_framework/mininode.py

@@ -361,6 +361,14 @@ class P2PInterface(P2PConnection):
 
     # Message receiving helper methods
 
+    def wait_for_tx(self, txid, timeout=60):
+        def test_function():
+            if not self.last_message.get('tx'):
+                return False
+            return self.last_message['tx'].tx.rehash() == txid
+
+        wait_until(test_function, timeout=timeout, lock=mininode_lock)
+
     def wait_for_block(self, blockhash, timeout=60):
         test_function = lambda: self.last_message.get("block") and self.last_message["block"].block.rehash() == blockhash
         wait_until(test_function, timeout=timeout, lock=mininode_lock)

test/functional/test_framework/util.py

@@ -216,7 +216,7 @@ def wait_until(predicate, *, attempts=float('inf'), timeout=float('inf'), lock=N
         time.sleep(0.05)
 
     # Print the cause of the timeout
-    predicate_source = inspect.getsourcelines(predicate)
+    predicate_source = "''''\n" + inspect.getsource(predicate) + "'''"
     logger.error("wait_until() failed. Predicate: {}".format(predicate_source))
     if attempt >= attempts:
         raise AssertionError("Predicate {} not true after {} attempts".format(predicate_source, attempts))

test/functional/test_runner.py

@@ -141,6 +141,7 @@ BASE_SCRIPTS = [
     'rpc_net.py',
     'wallet_keypool.py',
     'p2p_mempool.py',
+    'p2p_blocksonly.py',
     'mining_prioritisetransaction.py',
     'p2p_invalid_locator.py',
     'p2p_invalid_block.py',