Add tests and documentation for blocksonly #15990

  34 | @@ -35,3 +35,9 @@ blocks and transactions to fewer nodes.
  35 |  Reducing the maximum connected nodes to a minimum could be desirable if traffic
  36 |  limits are tiny. Keep in mind that bitcoin's trustless model works best if you are
  37 |  connected to a handful of nodes.
  38 | +
  39 | +## 4. Turn off transaction relay (`-blocksonly`)
  40 | +
  41 | +Forwarding transactions to peers increases the P2P traffic. To only sync blocks
  42 | +with other peers, you can disable transaction relay. Be reminded that this
  43 | +setting could hurt your privacy if used while a wallet is loaded.

---

  42 | +        assert_equal(self.nodes[0].getnetworkinfo()['localrelay'], False)
  43 | +        with self.nodes[0].assert_debug_log(['transaction sent in violation of protocol peer=0']):
  44 | +            self.nodes[0].p2p.send_message(msg_tx(FromHex(CTransaction(), sigtx)))
  45 | +            self.nodes[0].p2p.sync_with_ping()
  46 | +
  47 | +        self.log.info('Check that txs from wallet (or rpc) are not rejected and relayed to other peers')

---

  40 | +
  41 | +Forwarding transactions to peers increases the P2P traffic. To only sync blocks
  42 | +with other peers, you can disable transaction relay.
  43 | +
  44 | +Be reminded that this setting could hurt your privacy if used while a wallet is
  45 | +loaded or you use the node to broadcast transactions.

---

  10 | +from test_framework.util import assert_equal
  11 | +
  12 | +
  13 | +class P2PBlocksOnly(BitcoinTestFramework):
  14 | +    def set_test_params(self):
  15 | +        self.setup_clean_chain = False

---

 382 | @@ -383,7 +383,7 @@ void SetupServerArgs()
 383 |      gArgs.AddArg("-blocksdir=<dir>", "Specify blocks directory (default: <datadir>/blocks)", false, OptionsCategory::OPTIONS);
 384 |      gArgs.AddArg("-blocknotify=<cmd>", "Execute command when the best block changes (%s in cmd is replaced by block hash)", false, OptionsCategory::OPTIONS);
 385 |      gArgs.AddArg("-blockreconstructionextratxn=<n>", strprintf("Extra transactions to keep in memory for compact block reconstructions (default: %u)", DEFAULT_BLOCK_RECONSTRUCTION_EXTRA_TXN), false, OptionsCategory::OPTIONS);
 386 | -    gArgs.AddArg("-blocksonly", strprintf("Whether to operate in a blocks only mode (default: %u)", DEFAULT_BLOCKSONLY), true, OptionsCategory::OPTIONS);
 387 | +    gArgs.AddArg("-blocksonly", strprintf("Whether to reject transactions from network peers. Transactions from the wallet or RPC are not affected. (default: %u)", DEFAULT_BLOCKSONLY), false, OptionsCategory::OPTIONS);

---

  34 | @@ -35,3 +35,14 @@ blocks and transactions to fewer nodes.
  35 |  Reducing the maximum connected nodes to a minimum could be desirable if traffic
  36 |  limits are tiny. Keep in mind that bitcoin's trustless model works best if you are
  37 |  connected to a handful of nodes.
  38 | +
  39 | +## 4. Turn off transaction relay (`-blocksonly`)

---

  43 | +
  44 | +Be reminded that this setting could hurt your privacy if used while a wallet is
  45 | +loaded or if you use the node to broadcast transactions.
  46 | +
  47 | +Moreover, this makes block propagation slower because compact block relay can
  48 | +only be used when transaction relay is enabled

---

  40 | +            }],
  41 | +        )['hex']
  42 | +        assert_equal(self.nodes[0].getnetworkinfo()['localrelay'], False)
  43 | +        with self.nodes[0].assert_debug_log(['transaction sent in violation of protocol peer=0']):
  44 | +            self.nodes[0].p2p.send_message(msg_tx(FromHex(CTransaction(), sigtx)))
  45 | +            self.nodes[0].p2p.sync_with_ping()

---