Add ZeroMQ support. Notify blocks and transactions via ZeroMQ

Continues Johnathan Corgan's work.
Publishing multipart messages

Bugfix: Add missing zmq header includes

Bugfix: Adjust build system to link ZeroMQ code for Qt binaries

Author: Jeff Garzik

configure.ac

@@ -137,6 +137,12 @@ AC_ARG_ENABLE([glibc-back-compat],
   [use_glibc_compat=$enableval],
   [use_glibc_compat=no])
 
+AC_ARG_ENABLE([zmq],
+  [AC_HELP_STRING([--disable-zmq],
+  [Disable ZMQ notifications])],
+  [use_zmq=$enableval],
+  [use_zmq=yes])
+
 AC_ARG_WITH([protoc-bindir],[AS_HELP_STRING([--with-protoc-bindir=BIN_DIR],[specify protoc bin path])], [protoc_bin_path=$withval], [])
 
 # Enable debug 
@@ -833,6 +839,22 @@ if test x$bitcoin_enable_qt != xno; then
   fi
 fi
 
+# conditional search for and use libzmq
+AC_MSG_CHECKING([whether to build ZMQ support])
+if test "x$use_zmq" = "xyes"; then
+  AC_MSG_RESULT([yes])
+  PKG_CHECK_MODULES([ZMQ],[libzmq],
+    [AC_DEFINE([ENABLE_ZMQ],[1],[Define to 1 to enable ZMQ functions])],
+    [AC_DEFINE([ENABLE_ZMQ],[0],[Define to 1 to enable ZMQ functions])
+     AC_MSG_WARN([libzmq not found, disabling])
+     use_zmq=no])
+else
+  AC_MSG_RESULT([no, --disable-zmq used])
+  AC_DEFINE_UNQUOTED([ENABLE_ZMQ],[0],[Define to 1 to enable ZMQ functions])
+fi
+
+AM_CONDITIONAL([ENABLE_ZMQ], [test "x$use_zmq" = "xyes"])
+
 AC_MSG_CHECKING([whether to build test_bitcoin])
 if test x$use_tests = xyes; then
   AC_MSG_RESULT([yes])

contrib/zmq/zmq_sub.py

@@ -0,0 +1,37 @@
+#!/usr/bin/env python2
+
+import array
+import binascii
+import zmq
+
+port = 28332
+
+zmqContext = zmq.Context()
+zmqSubSocket = zmqContext.socket(zmq.SUB)
+zmqSubSocket.setsockopt(zmq.SUBSCRIBE, "hashblock")
+zmqSubSocket.setsockopt(zmq.SUBSCRIBE, "hashtx")
+zmqSubSocket.setsockopt(zmq.SUBSCRIBE, "rawblock")
+zmqSubSocket.setsockopt(zmq.SUBSCRIBE, "rawtx")
+zmqSubSocket.connect("tcp://127.0.0.1:%i" % port)
+
+try:
+    while True:
+        msg = zmqSubSocket.recv_multipart()
+        topic = str(msg[0])
+        body = msg[1]
+
+        if topic == "hashblock":
+            print "- HASH BLOCK -"
+            print binascii.hexlify(body)
+        elif topic == "hashtx":
+            print '- HASH TX -'
+            print binascii.hexlify(body)
+        elif topic == "rawblock":
+            print "- RAW BLOCK HEADER -"
+            print binascii.hexlify(body[:80])
+        elif topic == "rawtx":
+            print '- RAW TX -'
+            print binascii.hexlify(body)
+
+except KeyboardInterrupt:
+    zmqContext.destroy()

doc/zmq.md

@@ -0,0 +1,98 @@
+# Block and Transaction Broadcasting With ZeroMQ
+
+[ZeroMQ](http://zeromq.org/) is a lightweight wrapper around TCP
+connections, inter-process communications, and shared-memory,
+providing various message-oriented semantics such as publish/subcribe,
+request/reply, and push/pull.
+
+The Bitcoin Core daemon can be configured to act as a trusted "border
+router", implementing the bitcoin wire protocol and relay, making
+consensus decisions, maintaining the local blockchain database,
+broadcasting locally generated transactions into the network, and
+providing a queryable RPC interface to interact on a polled basis for
+requesting blockchain related data. However, there exists only a
+limited service to notify external software of events like the arrival
+of new blocks or transactions.
+
+The ZeroMQ facility implements a notification interface through a
+set of specific notifiers. Currently there are notifiers that publish
+blocks and transactions. This read-only facility requires only the
+connection of a corresponding ZeroMQ subscriber port in receiving 
+software; it is not authenticated nor is there any two-way protocol
+involvement. Therefore, subscribers should validate the received data
+since it may be out of date, incomplete or even invalid.
+
+ZeroMQ sockets are self-connecting and self-healing; that is, connects
+made between two endpoints will be automatically restored after an
+outage, and either end may be freely started or stopped in any order.
+
+Because ZeroMQ is message oriented, subscribers receive transactions
+and blocks all-at-once and do not need to implement any sort of
+buffering or reassembly.
+
+## Prerequisites
+
+The ZeroMQ feature in Bitcoin Core uses only a very small part of the
+ZeroMQ C API, and is thus compatible with any version of ZeroMQ
+from 2.1 onward, including all versions in the 3.x and 4.x release
+series. Typically, it is packaged by distributions as something like
+*libzmq-dev*.
+
+The C++ wrapper for ZeroMQ is *not* needed.
+
+## Enabling
+
+By default, the ZeroMQ port functionality is enabled. Two steps are
+required to enable--compiling in the ZeroMQ code, and configuring
+runtime operation on the command-line or configuration file.
+
+    $ ./configure --enable-zmq (other options)
+
+This will produce a binary that is capable of providing the ZeroMQ
+facility, but will not do so until also configured properly.
+
+## Usage
+
+Currently, the following notifications are supported:
+
+    -zmqpubhashtx=address
+    -zmqpubhashblock=address
+    -zmqpubrawblock=address
+    -zmqpubrawtx=address
+
+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.
+
+For instance:
+
+    $ bitcoind -zmqpubhashtx=tcp://127.0.0.1:28332 -zmqpubrawtx=ipc:///tmp/bitcoind.tx.raw
+
+Each PUB notification has a topic and body, where the header
+corresponds to the notification type. For instance, for the notification
+`-zmqpubhashtx` the topic is `hashtx` (no null terminator) and the body is the
+hexadecimal transaction hash (32 bytes).
+
+These options can also be provided in bitcoin.conf.
+
+ZeroMQ endpoint specifiers for TCP (and others) are documented in the
+[ZeroMQ API](http://api.zeromq.org).
+
+Client side, then, the ZeroMQ subscriber socket must have the
+ZMQ_SUBSCRIBE option set to one or either of these prefixes (for instance, just `hash`); without
+doing so will result in no messages arriving. Please see `contrib/zmq/zmq_sub.py`
+for a working example.
+
+## Remarks
+
+From the perspective of bitcoind, the ZeroMQ socket is write-only; PUB
+sockets don't even have a read function. Thus, there is no state
+introduced into bitcoind directly. Furthermore, no information is
+broadcast that wasn't already received from the public P2P network.
+
+No authentication or authorization is done on connecting clients; it
+is assumed that the ZeroMQ port is exposed only to trusted entities,
+using other means such as firewalling.
+
+Note that when the block chain tip changes, a reorganisation may occur and just
+the tip will be notified. It is up to the subscriber to retrieve the chain
+from the last known block to the new tip.

src/Makefile.am

@@ -48,6 +48,9 @@ if ENABLE_WALLET
 BITCOIN_INCLUDES += $(BDB_CPPFLAGS)
 EXTRA_LIBRARIES += libbitcoin_wallet.a
 endif
+if ENABLE_ZMQ
+EXTRA_LIBRARIES += libbitcoin_zmq.a
+endif
 
 if BUILD_BITCOIN_LIBS
 lib_LTLIBRARIES = libbitcoinconsensus.la
@@ -157,7 +160,12 @@ BITCOIN_CORE_H = \
   wallet/db.h \
   wallet/wallet.h \
   wallet/wallet_ismine.h \
-  wallet/walletdb.h
+  wallet/walletdb.h \
+  zmq/zmqabstractnotifier.h \
+  zmq/zmqconfig.h\
+  zmq/zmqnotificationinterface.h \
+  zmq/zmqpublishnotifier.h
+
 
 obj/build.h: FORCE
 	@$(MKDIR_P) $(builddir)/obj
@@ -199,6 +207,17 @@ libbitcoin_server_a_SOURCES = \
   validationinterface.cpp \
   $(BITCOIN_CORE_H)
 
+if ENABLE_ZMQ
+LIBBITCOIN_ZMQ=libbitcoin_zmq.a
+
+libbitcoin_zmq_a_CPPFLAGS = $(BITCOIN_INCLUDES)
+libbitcoin_zmq_a_SOURCES = \
+  zmq/zmqabstractnotifier.cpp \
+  zmq/zmqnotificationinterface.cpp \
+  zmq/zmqpublishnotifier.cpp
+endif
+
+
 # wallet: shared between bitcoind and bitcoin-qt, but only linked
 # when wallet enabled
 libbitcoin_wallet_a_CPPFLAGS = $(BITCOIN_INCLUDES)
@@ -320,12 +339,15 @@ bitcoind_LDADD = \
   $(LIBMEMENV) \
   $(LIBSECP256K1)
 
+if ENABLE_ZMQ
+bitcoind_LDADD += $(LIBBITCOIN_ZMQ) $(ZMQ_LIBS)
+endif
+
 if ENABLE_WALLET
 bitcoind_LDADD += libbitcoin_wallet.a
 endif
 
 bitcoind_LDADD += $(BOOST_LIBS) $(BDB_LIBS) $(SSL_LIBS) $(CRYPTO_LIBS) $(MINIUPNPC_LIBS) $(EVENT_PTHREADS_LIBS) $(EVENT_LIBS)
-#
 
 # bitcoin-cli binary #
 bitcoin_cli_SOURCES = bitcoin-cli.cpp

src/Makefile.qt.include

@@ -361,6 +361,9 @@ qt_bitcoin_qt_LDADD = qt/libbitcoinqt.a $(LIBBITCOIN_SERVER)
 if ENABLE_WALLET
 qt_bitcoin_qt_LDADD += $(LIBBITCOIN_WALLET)
 endif
+if ENABLE_ZMQ
+qt_bitcoin_qt_LDADD += $(LIBBITCOIN_ZMQ) $(ZMQ_LIBS)
+endif
 qt_bitcoin_qt_LDADD += $(LIBBITCOIN_CLI) $(LIBBITCOIN_COMMON) $(LIBBITCOIN_UTIL) $(LIBBITCOIN_CRYPTO) $(LIBBITCOIN_UNIVALUE) $(LIBLEVELDB) $(LIBMEMENV) \
   $(BOOST_LIBS) $(QT_LIBS) $(QT_DBUS_LIBS) $(QR_LIBS) $(PROTOBUF_LIBS) $(BDB_LIBS) $(SSL_LIBS) $(CRYPTO_LIBS) $(MINIUPNPC_LIBS) $(LIBSECP256K1) \
   $(EVENT_PTHREADS_LIBS) $(EVENT_LIBS)

src/Makefile.qttest.include

@@ -30,6 +30,9 @@ qt_test_test_bitcoin_qt_LDADD = $(LIBBITCOINQT) $(LIBBITCOIN_SERVER)
 if ENABLE_WALLET
 qt_test_test_bitcoin_qt_LDADD += $(LIBBITCOIN_WALLET)
 endif
+if ENABLE_ZMQ
+qt_test_test_bitcoin_qt_LDADD += $(LIBBITCOIN_ZMQ) $(ZMQ_LIBS)
+endif
 qt_test_test_bitcoin_qt_LDADD += $(LIBBITCOIN_CLI) $(LIBBITCOIN_COMMON) $(LIBBITCOIN_UTIL) $(LIBBITCOIN_CRYPTO) $(LIBBITCOIN_UNIVALUE) $(LIBLEVELDB) \
   $(LIBMEMENV) $(BOOST_LIBS) $(QT_DBUS_LIBS) $(QT_TEST_LIBS) $(QT_LIBS) \
   $(QR_LIBS) $(PROTOBUF_LIBS) $(BDB_LIBS) $(SSL_LIBS) $(CRYPTO_LIBS) $(MINIUPNPC_LIBS) $(LIBSECP256K1) \

src/Makefile.test.include

@@ -100,6 +100,10 @@ endif
 test_test_bitcoin_LDADD += $(LIBBITCOIN_CONSENSUS) $(BDB_LIBS) $(SSL_LIBS) $(CRYPTO_LIBS) $(MINIUPNPC_LIBS)
 test_test_bitcoin_LDFLAGS = $(RELDFLAGS) $(AM_LDFLAGS) $(LIBTOOL_APP_LDFLAGS) -static
 
+if ENABLE_ZMQ
+test_test_bitcoin_LDADD += $(ZMQ_LIBS)
+endif
+
 nodist_test_test_bitcoin_SOURCES = $(GENERATED_TEST_FILES)
 
 $(BITCOIN_TESTS): $(GENERATED_TEST_FILES)

src/init.cpp

@@ -38,7 +38,6 @@
 #include "wallet/wallet.h"
 #include "wallet/walletdb.h"
 #endif
-
 #include <stdint.h>
 #include <stdio.h>
 
@@ -55,13 +54,21 @@
 #include <boost/thread.hpp>
 #include <openssl/crypto.h>
 
+#if ENABLE_ZMQ
+#include "zmq/zmqnotificationinterface.h"
+#endif
+
 using namespace std;
 
 #ifdef ENABLE_WALLET
 CWallet* pwalletMain = NULL;
 #endif
 bool fFeeEstimatesInitialized = false;
 
+#if ENABLE_ZMQ
+static CZMQNotificationInterface* pzmqNotificationInterface = NULL;
+#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
@@ -211,6 +218,16 @@ void Shutdown()
     if (pwalletMain)
         pwalletMain->Flush(true);
 #endif
+
+#if ENABLE_ZMQ
+    if (pzmqNotificationInterface) {
+        UnregisterValidationInterface(pzmqNotificationInterface);
+        pzmqNotificationInterface->Shutdown();
+        delete pzmqNotificationInterface;
+        pzmqNotificationInterface = NULL;
+    }
+#endif
+
 #ifndef WIN32
     try {
         boost::filesystem::remove(GetPidFile());
@@ -375,6 +392,14 @@ std::string HelpMessage(HelpMessageMode mode)
         " " + _("(1 = keep tx meta data e.g. account owner and payment request information, 2 = drop tx meta data)"));
 #endif
 
+#if ENABLE_ZMQ
+    strUsage += HelpMessageGroup(_("ZeroMQ notification options:"));
+    strUsage += HelpMessageOpt("-zmqpubhashblock=<address>", _("Enable publish hash block in <address>"));
+    strUsage += HelpMessageOpt("-zmqpubhashtransaction=<address>", _("Enable publish hash transaction in <address>"));
+    strUsage += HelpMessageOpt("-zmqpubrawblock=<address>", _("Enable publish raw block in <address>"));
+    strUsage += HelpMessageOpt("-zmqpubrawtransaction=<address>", _("Enable publish raw transaction in <address>"));
+#endif
+
     strUsage += HelpMessageGroup(_("Debugging/Testing options:"));
     if (showDebug)
     {
@@ -1125,6 +1150,15 @@ bool AppInit2(boost::thread_group& threadGroup, CScheduler& scheduler)
     BOOST_FOREACH(const std::string& strDest, mapMultiArgs["-seednode"])
         AddOneShot(strDest);
 
+#if ENABLE_ZMQ
+    pzmqNotificationInterface = CZMQNotificationInterface::CreateWithArguments(mapArgs);
+
+    if (pzmqNotificationInterface) {
+        pzmqNotificationInterface->Initialize();
+        RegisterValidationInterface(pzmqNotificationInterface);
+    }
+#endif
+
     // ********************************************************* Step 7: load block chain
 
     fReindex = GetBoolArg("-reindex", false);

src/validationinterface.cpp

@@ -45,7 +45,6 @@ void UnregisterAllValidationInterfaces() {
     g_signals.SetBestChain.disconnect_all_slots();
     g_signals.UpdatedTransaction.disconnect_all_slots();
     g_signals.SyncTransaction.disconnect_all_slots();
-    g_signals.UpdatedTransaction.disconnect_all_slots();
     g_signals.UpdatedBlockTip.disconnect_all_slots();
 }
 

src/zmq/zmqabstractnotifier.cpp

@@ -0,0 +1,22 @@
+// Copyright (c) 2015 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 "zmqabstractnotifier.h"
+#include "util.h"
+
+
+CZMQAbstractNotifier::~CZMQAbstractNotifier()
+{
+    assert(!psocket);
+}
+
+bool CZMQAbstractNotifier::NotifyBlock(const uint256 &/*hash*/)
+{
+    return true;
+}
+
+bool CZMQAbstractNotifier::NotifyTransaction(const CTransaction &/*transaction*/)
+{
+    return true;
+}