Merge bitcoin#18309: zmq: Add support to listen on multiple interfaces

e66870c zmq: Append address to notify log output (nthumann)
241803d test: Add zmq test to support multiple interfaces (nthumann)
a0b2e5c doc: Add release notes to support multiple interfaces (nthumann)
b1c3f18 doc: Adjust ZMQ usage to support multiple interfaces (nthumann)
347c94f zmq: Add support to listen on multiple interfaces (Nicolas Thumann)

Pull request description:

  This PR adds support for ZeroMQ to listen on multiple interfaces, just like the RPC server.
  Currently, if you specify more than one e.g. `zmqpubhashblock` paramter, only the first one will be used. Therefore a user may be forced to listen on all interfaces (e.g. `zmqpubhashblock=0.0.0.0:28332`), which can result in an increased attack surface.
  With this PR a user can specify multiple interfaces to listen on, e.g.
  `-zmqpubhashblock=tcp://127.0.0.1:28332 -zmqpubhashblock=tcp://192.168.1.123:28332`.

ACKs for top commit:
  laanwj:
    Code review ACK e66870c
  instagibbs:
    reACK bitcoin@e66870c

Tree-SHA512: f38ab4a6ff00dc821e5f4842508cefadb701e70bb3893992c1b32049be20247c8aa9476a1f886050c5f17fe7f2ce99ee30193ce2c81a7482a5a51f8fc22300c7

doc/release-notes-18309.md

@@ -0,0 +1,4 @@
+Command-line options
+-----------------------------
+
+The same ZeroMQ notification (e.g. `-zmqpubhashtx=address`) can now be specified multiple times to publish the same notification to different ZeroMQ sockets.

doc/zmq.md

@@ -80,6 +80,7 @@ Currently, the following notifications are supported:
 
 The socket type is PUB and the address must be a valid ZeroMQ socket
 address. The same address can be used in more than one notification.
+The same notification can be specified more than once.
 
 The option to set the PUB socket's outbound message high water mark
 (SNDHWM) may be set individually for each notification:
@@ -108,6 +109,7 @@ The high water mark value must be an integer greater than or equal to 0.
 For instance:
 
     $ dashd -zmqpubhashtx=tcp://127.0.0.1:28332 \
+               -zmqpubhashtx=tcp://192.168.1.2:28332 \
                -zmqpubrawtx=ipc:///tmp/dashd.tx.raw \
                -zmqpubhashtxhwm=10000
 

src/zmq/zmqnotificationinterface.cpp

@@ -55,10 +55,8 @@ CZMQNotificationInterface* CZMQNotificationInterface::Create()
     for (const auto& entry : factories)
     {
         std::string arg("-zmq" + entry.first);
-        if (gArgs.IsArgSet(arg))
-        {
-            const auto& factory = entry.second;
-            const std::string address = gArgs.GetArg(arg, "");
+        const auto& factory = entry.second;
+        for (const std::string& address : gArgs.GetArgs(arg)) {
             std::unique_ptr<CZMQAbstractNotifier> notifier = factory();
             notifier->SetType(entry.first);
             notifier->SetAddress(address);

src/zmq/zmqpublishnotifier.cpp

@@ -198,7 +198,7 @@ bool CZMQAbstractPublishNotifier::SendZmqMessage(const char *command, const void
 bool CZMQPublishHashBlockNotifier::NotifyBlock(const CBlockIndex *pindex)
 {
     uint256 hash = pindex->GetBlockHash();
-    LogPrint(BCLog::ZMQ, "zmq: Publish hashblock %s\n", hash.GetHex());
+    LogPrint(BCLog::ZMQ, "zmq: Publish hashblock %s to %s\n", hash.GetHex(), this->address);
     char data[32];
     for (unsigned int i = 0; i < 32; i++)
         data[31 - i] = hash.begin()[i];
@@ -218,7 +218,7 @@ bool CZMQPublishHashChainLockNotifier::NotifyChainLock(const CBlockIndex *pindex
 bool CZMQPublishHashTransactionNotifier::NotifyTransaction(const CTransaction &transaction)
 {
     uint256 hash = transaction.GetHash();
-    LogPrint(BCLog::ZMQ, "zmq: Publish hashtx %s\n", hash.GetHex());
+    LogPrint(BCLog::ZMQ, "zmq: Publish hashtx %s to %s\n", hash.GetHex(), this->address);
     char data[32];
     for (unsigned int i = 0; i < 32; i++)
         data[31 - i] = hash.begin()[i];
@@ -279,7 +279,7 @@ bool CZMQPublishHashRecoveredSigNotifier::NotifyRecoveredSig(const std::shared_p
 
 bool CZMQPublishRawBlockNotifier::NotifyBlock(const CBlockIndex *pindex)
 {
-    LogPrint(BCLog::ZMQ, "zmq: Publish rawblock %s\n", pindex->GetBlockHash().GetHex());
+    LogPrint(BCLog::ZMQ, "zmq: Publish rawblock %s to %s\n", pindex->GetBlockHash().GetHex(), this->address);
 
     const Consensus::Params& consensusParams = Params().GetConsensus();
     CDataStream ss(SER_NETWORK, PROTOCOL_VERSION);
@@ -344,7 +344,7 @@ bool CZMQPublishRawChainLockSigNotifier::NotifyChainLock(const CBlockIndex *pind
 bool CZMQPublishRawTransactionNotifier::NotifyTransaction(const CTransaction &transaction)
 {
     uint256 hash = transaction.GetHash();
-    LogPrint(BCLog::ZMQ, "zmq: Publish rawtx %s\n", hash.GetHex());
+    LogPrint(BCLog::ZMQ, "zmq: Publish rawtx %s to %s\n", hash.GetHex(), this->address);
     CDataStream ss(SER_NETWORK, PROTOCOL_VERSION);
     ss << transaction;
     return SendZmqMessage(MSG_RAWTX, &(*ss.begin()), ss.size());
@@ -353,7 +353,7 @@ bool CZMQPublishRawTransactionNotifier::NotifyTransaction(const CTransaction &tr
 bool CZMQPublishRawTransactionLockNotifier::NotifyTransactionLock(const CTransactionRef& transaction, const std::shared_ptr<const llmq::CInstantSendLock>& islock)
 {
     uint256 hash = transaction->GetHash();
-    LogPrint(BCLog::ZMQ, "zmq: Publish rawtxlock %s\n", hash.GetHex());
+    LogPrint(BCLog::ZMQ, "zmq: Publish rawtxlock %s to %s\n", hash.GetHex(), this->address);
     CDataStream ss(SER_NETWORK, PROTOCOL_VERSION);
     ss << *transaction;
     return SendZmqMessage(MSG_RAWTXLOCK, &(*ss.begin()), ss.size());
@@ -362,7 +362,7 @@ bool CZMQPublishRawTransactionLockNotifier::NotifyTransactionLock(const CTransac
 bool CZMQPublishRawTransactionLockSigNotifier::NotifyTransactionLock(const CTransactionRef& transaction, const std::shared_ptr<const llmq::CInstantSendLock>& islock)
 {
     uint256 hash = transaction->GetHash();
-    LogPrint(BCLog::ZMQ, "zmq: Publish rawtxlocksig %s\n", hash.GetHex());
+    LogPrint(BCLog::ZMQ, "zmq: Publish rawtxlocksig %s to %s\n", hash.GetHex(), this->address);
     CDataStream ss(SER_NETWORK, PROTOCOL_VERSION);
     ss << *transaction;
     ss << *islock;
@@ -372,7 +372,7 @@ bool CZMQPublishRawTransactionLockSigNotifier::NotifyTransactionLock(const CTran
 bool CZMQPublishRawGovernanceVoteNotifier::NotifyGovernanceVote(const std::shared_ptr<const CGovernanceVote>& vote)
 {
     uint256 nHash = vote->GetHash();
-    LogPrint(BCLog::ZMQ, "zmq: Publish rawgovernanceobject: hash = %s, vote = %d\n", nHash.ToString(), vote->ToString());
+    LogPrint(BCLog::ZMQ, "zmq: Publish rawgovernanceobject: hash = %s to %s, vote = %d\n", nHash.ToString(), this->address, vote->ToString());
     CDataStream ss(SER_NETWORK, PROTOCOL_VERSION);
     ss << *vote;
     return SendZmqMessage(MSG_RAWGVOTE, &(*ss.begin()), ss.size());
@@ -381,7 +381,7 @@ bool CZMQPublishRawGovernanceVoteNotifier::NotifyGovernanceVote(const std::share
 bool CZMQPublishRawGovernanceObjectNotifier::NotifyGovernanceObject(const std::shared_ptr<const CGovernanceObject>& govobj)
 {
     uint256 nHash = govobj->GetHash();
-    LogPrint(BCLog::ZMQ, "zmq: Publish rawgovernanceobject: hash = %s, type = %d\n", nHash.ToString(), ToUnderlying(govobj->GetObjectType()));
+    LogPrint(BCLog::ZMQ, "zmq: Publish rawgovernanceobject: hash = %s to %s, type = %d\n", nHash.ToString(), this->address, ToUnderlying(govobj->GetObjectType()));
     CDataStream ss(SER_NETWORK, PROTOCOL_VERSION);
     ss << *govobj;
     return SendZmqMessage(MSG_RAWGOBJ, &(*ss.begin()), ss.size());

test/functional/interface_zmq.py

@@ -78,6 +78,7 @@ def setup_nodes(self):
     def run_test(self):
         try:
             self._zmq_test()
+            self.test_multiple_interfaces()
         finally:
             # Destroy the ZMQ context.
             self.log.debug("Destroying ZMQ context")
@@ -131,5 +132,29 @@ def _zmq_test(self):
 
         assert_equal(self.nodes[1].getzmqnotifications(), [])
 
+    def test_multiple_interfaces(self):
+        import zmq
+        # Set up two subscribers with different addresses
+        subscribers = []
+        for i in range(2):
+            address = 'tcp://127.0.0.1:%d' % (28334 + i)
+            socket = self.zmq_context.socket(zmq.SUB)
+            socket.set(zmq.RCVTIMEO, 60000)
+            hashblock = ZMQSubscriber(socket, b"hashblock")
+            socket.connect(address)
+            subscribers.append({'address': address, 'hashblock': hashblock})
+
+        self.restart_node(0, ['-zmqpub%s=%s' % (subscriber['hashblock'].topic.decode(), subscriber['address']) for subscriber in subscribers])
+
+        # Relax so that the subscriber is ready before publishing zmq messages
+        sleep(0.2)
+
+        # Generate 1 block in nodes[0] and receive all notifications
+        self.nodes[0].generatetoaddress(1, ADDRESS_BCRT1_UNSPENDABLE)
+
+        # Should receive the same block hash on both subscribers
+        assert_equal(self.nodes[0].getbestblockhash(), subscribers[0]['hashblock'].receive().hex())
+        assert_equal(self.nodes[0].getbestblockhash(), subscribers[1]['hashblock'].receive().hex())
+
 if __name__ == '__main__':
     ZMQTest().main()