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Add barebones IPC framework to bitcoin-qt and bitcoind
This adds some IPC functions and classes in src/ipc/ that let bitcoin-qt fork a bitcoind process and communicate with it over a socketpair. Only a handful of IPC calls are implemented, but this demonstrates a working framework supporting bidirectional IPC calls (requests from bitcoin-qt to bitcoind and notifications from bitcoind to bitcoin-qt). The IPC protocol used in this implementation is Cap'n Proto (https://capnproto.org/), but this could be swapped out for another protocol. Can'n Proto types and libraries are only accessed in ipc/server.cpp and ipc/client.cpp, and not in any headers or other parts of bitcoin code.
1 parent 29efc39 commit 0ca73bc

37 files changed

+1939
-128
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‎configure.ac‎

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@@ -1111,6 +1111,7 @@ AM_CONDITIONAL([USE_LCOV],[test x$use_lcov = xyes])
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AM_CONDITIONAL([GLIBC_BACK_COMPAT],[test x$use_glibc_compat = xyes])
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AM_CONDITIONAL([HARDEN],[test x$use_hardening = xyes])
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AC_DEFINE_UNQUOTED(BITCOIN_DAEMON_NAME, "$BITCOIN_DAEMON_NAME", [Base name of bitcoind executable])
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AC_DEFINE(CLIENT_VERSION_MAJOR, _CLIENT_VERSION_MAJOR, [Major version])
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AC_DEFINE(CLIENT_VERSION_MINOR, _CLIENT_VERSION_MINOR, [Minor version])
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AC_DEFINE(CLIENT_VERSION_REVISION, _CLIENT_VERSION_REVISION, [Build revision])

‎src/Makefile.am‎

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@@ -102,6 +102,12 @@ BITCOIN_CORE_H = \
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httpserver.h \
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indirectmap.h \
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init.h \
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ipc/client.h \
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ipc/interfaces.h \
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ipc/messages.capnp.h \
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ipc/serialize.h \
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ipc/server.h \
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ipc/util.h \
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key.h \
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keystore.h \
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dbwrapper.h \
@@ -173,7 +179,7 @@ obj/build.h: FORCE
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libbitcoin_util_a-clientversion.$(OBJEXT): obj/build.h
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# server: shared between bitcoind and bitcoin-qt
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libbitcoin_server_a_CPPFLAGS = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES) $(MINIUPNPC_CPPFLAGS) $(EVENT_CFLAGS) $(EVENT_PTHREADS_CFLAGS)
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libbitcoin_server_a_CPPFLAGS = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES) $(MINIUPNPC_CPPFLAGS) $(EVENT_CFLAGS) $(EVENT_PTHREADS_CFLAGS) $(CAPNP_RPC_CFLAGS)
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libbitcoin_server_a_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
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libbitcoin_server_a_SOURCES = \
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addrman.cpp \
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compat/glibc_sanity.cpp \
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compat/glibcxx_sanity.cpp \
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compat/strnlen.cpp \
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ipc/client.cpp \
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ipc/interfaces.cpp \
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ipc/messages.capnp \
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ipc/messages.capnp.c++ \
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ipc/serialize.cpp \
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ipc/server.cpp \
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ipc/util.cpp \
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random.cpp \
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rpc/protocol.cpp \
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support/cleanse.cpp \
@@ -374,7 +387,7 @@ bitcoind_LDADD = \
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$(LIBMEMENV) \
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$(LIBSECP256K1)
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bitcoind_LDADD += $(BOOST_LIBS) $(BDB_LIBS) $(SSL_LIBS) $(CRYPTO_LIBS) $(MINIUPNPC_LIBS) $(EVENT_PTHREADS_LIBS) $(EVENT_LIBS) $(ZMQ_LIBS)
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bitcoind_LDADD += $(BOOST_LIBS) $(BDB_LIBS) $(SSL_LIBS) $(CRYPTO_LIBS) $(MINIUPNPC_LIBS) $(EVENT_PTHREADS_LIBS) $(EVENT_LIBS) $(ZMQ_LIBS) $(CAPNP_RPC_LIBS)
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# bitcoin-cli binary #
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bitcoin_cli_SOURCES = bitcoin-cli.cpp

‎src/Makefile.qt.include‎

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@@ -409,7 +409,7 @@ qt_bitcoin_qt_LDADD += $(LIBBITCOIN_ZMQ) $(ZMQ_LIBS)
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endif
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qt_bitcoin_qt_LDADD += $(LIBBITCOIN_CLI) $(LIBBITCOIN_COMMON) $(LIBBITCOIN_UTIL) $(LIBBITCOIN_CONSENSUS) $(LIBBITCOIN_CRYPTO) $(LIBUNIVALUE) $(LIBLEVELDB) $(LIBMEMENV) \
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$(BOOST_LIBS) $(QT_LIBS) $(QT_DBUS_LIBS) $(QR_LIBS) $(PROTOBUF_LIBS) $(BDB_LIBS) $(SSL_LIBS) $(CRYPTO_LIBS) $(MINIUPNPC_LIBS) $(LIBSECP256K1) \
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$(EVENT_PTHREADS_LIBS) $(EVENT_LIBS)
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$(EVENT_PTHREADS_LIBS) $(EVENT_LIBS) $(CAPNP_RPC_LIBS)
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qt_bitcoin_qt_LDFLAGS = $(RELDFLAGS) $(AM_LDFLAGS) $(QT_LDFLAGS) $(LIBTOOL_APP_LDFLAGS)
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qt_bitcoin_qt_LIBTOOLFLAGS = --tag CXX
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‎src/Makefile.qttest.include‎

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@@ -61,7 +61,7 @@ endif
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qt_test_test_bitcoin_qt_LDADD += $(LIBBITCOIN_CLI) $(LIBBITCOIN_COMMON) $(LIBBITCOIN_UTIL) $(LIBBITCOIN_CONSENSUS) $(LIBBITCOIN_CRYPTO) $(LIBUNIVALUE) $(LIBLEVELDB) \
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$(LIBMEMENV) $(BOOST_LIBS) $(QT_DBUS_LIBS) $(QT_TEST_LIBS) $(QT_LIBS) \
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$(QR_LIBS) $(PROTOBUF_LIBS) $(BDB_LIBS) $(SSL_LIBS) $(CRYPTO_LIBS) $(MINIUPNPC_LIBS) $(LIBSECP256K1) \
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$(EVENT_PTHREADS_LIBS) $(EVENT_LIBS)
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$(EVENT_PTHREADS_LIBS) $(EVENT_LIBS) $(CAPNP_RPC_LIBS)
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qt_test_test_bitcoin_qt_LDFLAGS = $(RELDFLAGS) $(AM_LDFLAGS) $(QT_LDFLAGS) $(LIBTOOL_APP_LDFLAGS)
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qt_test_test_bitcoin_qt_CXXFLAGS = $(AM_CXXFLAGS) $(QT_PIE_FLAGS)
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‎src/bitcoind.cpp‎

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#include "compat.h"
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#include "rpc/server.h"
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#include "init.h"
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#include "ipc/server.h"
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#include "noui.h"
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#include "scheduler.h"
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#include "util.h"
@@ -188,6 +189,13 @@ bool AppInit(int argc, char* argv[])
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int main(int argc, char* argv[])
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{
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// Check if bitcoind is being invoked as an IPC server. If so, then bypass
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// normal execution and just respond to requests from the IPC channel.
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int exitStatus;
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if (ipc::StartServer(argc, argv, exitStatus)) {
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return exitStatus;
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}
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SetupEnvironment();
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// Connect bitcoind signal handlers

‎src/ipc/README.md‎

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Bitcoin Interprocess Communication
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==================================
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The IPC functions and classes in `src/ipc/` allow the `bitcoin-qt` process to
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fork a `bitcoind` process and communicate with it over a socketpair. This gives
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`bitcoin-qt` a code a bit of modularity, avoiding a monolithic architecture
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where UI, P2P, wallet, consensus, and database code all runs in a single
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process.
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In the future, the IPC mechanism could be extended to allow other subdivisions
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of functionality. For example, wallet code could run in a separate process from
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P2P code. Also in the future, IPC sockets could also be exposed more publicly.
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For example, exposed IPC server sockets could allow a `bitcoin-qt` process to
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control a `bitcoind` process other than the one it spawns internally. These
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changes would be straightforward to implement, but would create security,
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backwards-compatibility, complexity, and maintainablity concerns, so would
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require further discussion.
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The IPC protocol used is [Cap'n Proto](https://capnproto.org/), but the protocol
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could be swapped out for another protocol (such as JSON-RPC with long polling)
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without changing any code outside of the `src/ipc/` directory. No Cap'n Proto
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types are used or headers included in any public interface.
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Here are the important files in the `src/ipc/` directory:
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Public Interfaces
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-----------------
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* `interfaces.h` – `Node`, `Wallet`, `Handler` interface definitions
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* `client.h` – `StartClient` function to spawn a `bitcoind` process and
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return a `Node` object controlling it through a socketpair.
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* `server.h` – `StartServer` function to allow a `bitcoind` process to
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open a socket file descriptor and respond to remote commands.
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Other Files
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-----------
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* `interfaces.cpp – In-process implementations of `Node`, `Wallet`, `Handler`
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interfaces.
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* `client.cpp – IPC implementations of `Node`, `Wallet`, `Handler`
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interfaces that forward calls to a socket.
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* `server.cpp – IPC implementation responding to client requests.
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* `messages.capnp – IPC interface definition.
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* `serialize.{h,cpp}` – Helper functions for translating IPC messages.
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* `util.{h,cpp}` – Helper functions for making and receiving IPC calls.

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