Merge #13570: RPC: Add new "getzmqnotifications" method

161e8d4 RPC: Add new getzmqnotifications method. (Daniel Kraft)
caac39b Make ZMQ notification interface instance global. (Daniel Kraft)

Pull request description:

  This adds a new RPC method `getzmqnotifications`, which returns information about all active ZMQ notification endpoints.  This is useful for software that layers on top of bitcoind, so it can verify that ZeroMQ is enabled and also figure out where it should listen.

  See #13526.

Tree-SHA512: edce722925741c84ddbf7b3a879fc9db1907e5269d0d97138fe724035d93ee541c2118c24fa92f4197403f380d0e25c2fda5ca6c62d526792ea749cf527a99a0

Author: laanwj

doc/release-notes.md

@@ -79,6 +79,8 @@ RPC changes
    `getmempoolentry` when verbosity is set to `true` with sub-fields `ancestor`, `base`, `modified`
    and `descendant` denominated in BTC. This new field deprecates previous fee fields, such as
    `fee`, `modifiedfee`, `ancestorfee` and `descendantfee`.
+- The new RPC `getzmqnotifications` returns information about active ZMQ
+  notifications.
 
 External wallet files
 ---------------------

src/Makefile.am

@@ -194,7 +194,8 @@ BITCOIN_CORE_H = \
   zmq/zmqabstractnotifier.h \
   zmq/zmqconfig.h\
   zmq/zmqnotificationinterface.h \
-  zmq/zmqpublishnotifier.h
+  zmq/zmqpublishnotifier.h \
+  zmq/zmqrpc.h
 
 
 obj/build.h: FORCE
@@ -255,7 +256,8 @@ libbitcoin_zmq_a_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
 libbitcoin_zmq_a_SOURCES = \
   zmq/zmqabstractnotifier.cpp \
   zmq/zmqnotificationinterface.cpp \
-  zmq/zmqpublishnotifier.cpp
+  zmq/zmqpublishnotifier.cpp \
+  zmq/zmqrpc.cpp
 endif
 
 

src/init.cpp

@@ -63,6 +63,7 @@
 
 #if ENABLE_ZMQ
 #include <zmq/zmqnotificationinterface.h>
+#include <zmq/zmqrpc.h>
 #endif
 
 bool fFeeEstimatesInitialized = false;
@@ -100,10 +101,6 @@ void DummyWalletInit::AddWalletOptions() const
 const WalletInitInterface& g_wallet_init_interface = DummyWalletInit();
 #endif
 
-#if ENABLE_ZMQ
-static CZMQNotificationInterface* pzmqNotificationInterface = nullptr;
-#endif
-
 #ifdef WIN32
 // Win32 LevelDB doesn't use filedescriptors, and the ones used for
 // accessing block files don't count towards the fd_set size limit
@@ -269,10 +266,10 @@ void Shutdown()
     g_wallet_init_interface.Stop();
 
 #if ENABLE_ZMQ
-    if (pzmqNotificationInterface) {
-        UnregisterValidationInterface(pzmqNotificationInterface);
-        delete pzmqNotificationInterface;
-        pzmqNotificationInterface = nullptr;
+    if (g_zmq_notification_interface) {
+        UnregisterValidationInterface(g_zmq_notification_interface);
+        delete g_zmq_notification_interface;
+        g_zmq_notification_interface = nullptr;
     }
 #endif
 
@@ -1282,6 +1279,9 @@ bool AppInitMain()
      */
     RegisterAllCoreRPCCommands(tableRPC);
     g_wallet_init_interface.RegisterRPC(tableRPC);
+#if ENABLE_ZMQ
+    RegisterZMQRPCCommands(tableRPC);
+#endif
 
     /* Start the RPC server already.  It will be started in "warmup" mode
      * and not really process calls already (but it will signify connections
@@ -1398,10 +1398,10 @@ bool AppInitMain()
     }
 
 #if ENABLE_ZMQ
-    pzmqNotificationInterface = CZMQNotificationInterface::Create();
+    g_zmq_notification_interface = CZMQNotificationInterface::Create();
 
-    if (pzmqNotificationInterface) {
-        RegisterValidationInterface(pzmqNotificationInterface);
+    if (g_zmq_notification_interface) {
+        RegisterValidationInterface(g_zmq_notification_interface);
     }
 #endif
     uint64_t nMaxOutboundLimit = 0; //unlimited unless -maxuploadtarget is set

src/zmq/zmqnotificationinterface.cpp

@@ -1,4 +1,4 @@
-// Copyright (c) 2015-2017 The Bitcoin Core developers
+// Copyright (c) 2015-2018 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
@@ -29,6 +29,15 @@ CZMQNotificationInterface::~CZMQNotificationInterface()
     }
 }
 
+std::list<const CZMQAbstractNotifier*> CZMQNotificationInterface::GetActiveNotifiers() const
+{
+    std::list<const CZMQAbstractNotifier*> result;
+    for (const auto* n : notifiers) {
+        result.push_back(n);
+    }
+    return result;
+}
+
 CZMQNotificationInterface* CZMQNotificationInterface::Create()
 {
     CZMQNotificationInterface* notificationInterface = nullptr;
@@ -180,3 +189,5 @@ void CZMQNotificationInterface::BlockDisconnected(const std::shared_ptr<const CB
         TransactionAddedToMempool(ptx);
     }
 }
+
+CZMQNotificationInterface* g_zmq_notification_interface = nullptr;

src/zmq/zmqnotificationinterface.h

@@ -1,4 +1,4 @@
-// Copyright (c) 2015-2017 The Bitcoin Core developers
+// Copyright (c) 2015-2018 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
@@ -18,6 +18,8 @@ class CZMQNotificationInterface final : public CValidationInterface
 public:
     virtual ~CZMQNotificationInterface();
 
+    std::list<const CZMQAbstractNotifier*> GetActiveNotifiers() const;
+
     static CZMQNotificationInterface* Create();
 
 protected:
@@ -37,4 +39,6 @@ class CZMQNotificationInterface final : public CValidationInterface
     std::list<CZMQAbstractNotifier*> notifiers;
 };
 
+extern CZMQNotificationInterface* g_zmq_notification_interface;
+
 #endif // BITCOIN_ZMQ_ZMQNOTIFICATIONINTERFACE_H

src/zmq/zmqrpc.cpp

@@ -0,0 +1,61 @@
+// Copyright (c) 2018 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <zmq/zmqrpc.h>
+
+#include <rpc/server.h>
+#include <zmq/zmqabstractnotifier.h>
+#include <zmq/zmqnotificationinterface.h>
+
+#include <univalue.h>
+
+namespace {
+
+UniValue getzmqnotifications(const JSONRPCRequest& request)
+{
+    if (request.fHelp || request.params.size() != 0) {
+        throw std::runtime_error(
+            "getzmqnotifications\n"
+            "\nReturns information about the active ZeroMQ notifications.\n"
+            "\nResult:\n"
+            "[\n"
+            "  {                        (json object)\n"
+            "    \"type\": \"pubhashtx\",   (string) Type of notification\n"
+            "    \"address\": \"...\"       (string) Address of the publisher\n"
+            "  },\n"
+            "  ...\n"
+            "]\n"
+            "\nExamples:\n"
+            + HelpExampleCli("getzmqnotifications", "")
+            + HelpExampleRpc("getzmqnotifications", "")
+        );
+    }
+
+    UniValue result(UniValue::VARR);
+    if (g_zmq_notification_interface != nullptr) {
+        for (const auto* n : g_zmq_notification_interface->GetActiveNotifiers()) {
+            UniValue obj(UniValue::VOBJ);
+            obj.pushKV("type", n->GetType());
+            obj.pushKV("address", n->GetAddress());
+            result.push_back(obj);
+        }
+    }
+
+    return result;
+}
+
+const CRPCCommand commands[] =
+{ //  category              name                                actor (function)                argNames
+  //  -----------------     ------------------------            -----------------------         ----------
+    { "zmq",                "getzmqnotifications",              &getzmqnotifications,           {} },
+};
+
+} // anonymous namespace
+
+void RegisterZMQRPCCommands(CRPCTable& t)
+{
+    for (const auto& c : commands) {
+        t.appendCommand(c.name, &c);
+    }
+}

src/zmq/zmqrpc.h

@@ -0,0 +1,12 @@
+// Copyright (c) 2018 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef BITCOIN_ZMQ_ZMQRPC_H
+#define BITCOIN_ZMQ_ZMQRPC_H
+
+class CRPCTable;
+
+void RegisterZMQRPCCommands(CRPCTable& t);
+
+#endif // BITCOIN_ZMQ_ZMRRPC_H

test/functional/rpc_zmq.py

@@ -0,0 +1,33 @@
+#!/usr/bin/env python3
+# Copyright (c) 2018 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 for the ZMQ RPC methods."""
+
+from test_framework.test_framework import BitcoinTestFramework
+from test_framework.util import assert_equal
+
+
+class RPCZMQTest(BitcoinTestFramework):
+
+    address = "tcp://127.0.0.1:28332"
+
+    def set_test_params(self):
+        self.num_nodes = 1
+        self.setup_clean_chain = True
+
+    def run_test(self):
+        self._test_getzmqnotifications()
+
+    def _test_getzmqnotifications(self):
+        self.restart_node(0, extra_args=[])
+        assert_equal(self.nodes[0].getzmqnotifications(), [])
+
+        self.restart_node(0, extra_args=["-zmqpubhashtx=%s" % self.address])
+        assert_equal(self.nodes[0].getzmqnotifications(), [
+            {"type": "pubhashtx", "address": self.address},
+        ])
+
+
+if __name__ == '__main__':
+    RPCZMQTest().main()

test/functional/test_runner.py

@@ -116,6 +116,7 @@
     'feature_versionbits_warning.py',
     'rpc_preciousblock.py',
     'wallet_importprunedfunds.py',
+    'rpc_zmq.py',
     'rpc_signmessage.py',
     'feature_nulldummy.py',
     'mempool_accept.py',