Add --enable-rust configure switch

Introduce a way to optionally enable Rust integration for our builds. No
actual Rust code is added yet and specifying the flag has no effect
other than failing the build if rustc and cargo are unavailable.

Makefile.am

@@ -25,6 +25,12 @@ else
 TESTING_TOR_BINARY=$(top_builddir)/src/or/tor$(EXEEXT)
 endif
 
+if USE_RUST
+rust_ldadd=
+else
+rust_ldadd=
+endif
+
 include src/include.am
 include doc/include.am
 include contrib/include.am

configure.ac

@@ -55,6 +55,8 @@ AC_ARG_ENABLE(oss-fuzz,
    AS_HELP_STRING(--enable-oss-fuzz, [build extra fuzzers based on 'oss-fuzz' environment]))
 AC_ARG_ENABLE(memory-sentinels,
    AS_HELP_STRING(--disable-memory-sentinels, [disable code that tries to prevent some kinds of memory access bugs. For fuzzing only.]))
+AC_ARG_ENABLE(rust,
+   AS_HELP_STRING(--enable-rust, [enable rust integration]))
 
 if test "x$enable_coverage" != "xyes" -a "x$enable_asserts_in_tests" = "xno" ; then
     AC_MSG_ERROR([Can't disable assertions outside of coverage build])
@@ -65,6 +67,7 @@ AM_CONDITIONAL(COVERAGE_ENABLED, test "x$enable_coverage" = "xyes")
 AM_CONDITIONAL(DISABLE_ASSERTS_IN_UNIT_TESTS, test "x$enable_asserts_in_tests" = "xno")
 AM_CONDITIONAL(LIBFUZZER_ENABLED, test "x$enable_libfuzzer" = "xyes")
 AM_CONDITIONAL(OSS_FUZZ_ENABLED, test "x$enable_oss_fuzz" = "xyes")
+AM_CONDITIONAL(USE_RUST, test "x$enable_rust" = "xyes")
 
 if test "$enable_static_tor" = "yes"; then
   enable_static_libevent="yes";
@@ -249,6 +252,23 @@ if test "x$PYTHON" = "x"; then
 fi
 AM_CONDITIONAL(USEPYTHON, [test "x$PYTHON" != "x"])
 
+
+if test "x$enable_rust" = "xyes"; then
+  AC_ARG_VAR([RUSTC], [path to the rustc binary])
+  AC_CHECK_PROG([RUSTC], [rustc], [rustc],[no])
+  if test "x$RUSTC" = "xno"; then
+    AC_MSG_ERROR([rustc unavailable but rust integration requested.])
+  fi
+
+  AC_ARG_VAR([CARGO], [path to the cargo binary])
+  AC_CHECK_PROG([CARGO], [cargo], [cargo],[no])
+  if test "x$CARGO" = "xno"; then
+    AC_MSG_ERROR([cargo unavailable but rust integration requested.])
+  fi
+
+  AC_DEFINE([HAVE_RUST], 1, [have Rust])
+fi
+
 ifdef([AC_C_FLEXIBLE_ARRAY_MEMBER], [
 AC_C_FLEXIBLE_ARRAY_MEMBER
 ], [

src/include.am

@@ -2,6 +2,7 @@ include src/ext/include.am
 include src/trunnel/include.am
 include src/common/include.am
 include src/or/include.am
+include src/rust/include.am
 include src/test/include.am
 include src/tools/include.am
 include src/win32/include.am

src/or/include.am

@@ -123,7 +123,8 @@ src_or_tor_LDADD = src/or/libtor.a src/common/libor.a src/common/libor-ctime.a \
 	src/trace/libor-trace.a \
 	@TOR_ZLIB_LIBS@ @TOR_LIB_MATH@ @TOR_LIBEVENT_LIBS@ @TOR_OPENSSL_LIBS@ \
 	@TOR_LIB_WS32@ @TOR_LIB_GDI@ @CURVE25519_LIBS@ @TOR_SYSTEMD_LIBS@ \
-	@TOR_LZMA_LIBS@ @TOR_ZSTD_LIBS@
+	@TOR_LZMA_LIBS@ @TOR_ZSTD_LIBS@ \
+	$(rust_ldadd)
 
 if COVERAGE_ENABLED
 src_or_tor_cov_SOURCES = src/or/tor_main.c

src/test/fuzz/include.am

@@ -20,7 +20,8 @@ FUZZING_LIBS = \
 	@TOR_OPENSSL_LIBS@ @TOR_LIB_WS32@ @TOR_LIB_GDI@ @CURVE25519_LIBS@ \
 	@TOR_SYSTEMD_LIBS@ \
 	@TOR_LZMA_LIBS@ \
-	@TOR_ZSTD_LIBS@
+	@TOR_ZSTD_LIBS@ \
+	$(rust_ldadd)
 
 oss-fuzz-prereqs: \
 	src/or/libtor-testing.a \

src/test/include.am

@@ -181,7 +181,8 @@ src_test_test_switch_id_LDADD = \
 	src/common/libor-testing.a \
 	src/common/libor-ctime-testing.a \
 	@TOR_ZLIB_LIBS@ @TOR_LIB_MATH@ \
-	@TOR_LZMA_LIBS@ @TOR_ZSTD_LIBS@
+	@TOR_LZMA_LIBS@ @TOR_ZSTD_LIBS@ \
+	$(rust_ldadd)
 
 src_test_test_LDFLAGS = @TOR_LDFLAGS_zlib@ @TOR_LDFLAGS_openssl@ \
         @TOR_LDFLAGS_libevent@
@@ -196,7 +197,8 @@ src_test_test_LDADD = src/or/libtor-testing.a \
 	src/trace/libor-trace.a \
 	@TOR_ZLIB_LIBS@ @TOR_LIB_MATH@ @TOR_LIBEVENT_LIBS@ \
 	@TOR_OPENSSL_LIBS@ @TOR_LIB_WS32@ @TOR_LIB_GDI@ @CURVE25519_LIBS@ \
-	@TOR_SYSTEMD_LIBS@ @TOR_LZMA_LIBS@ @TOR_ZSTD_LIBS@
+	@TOR_SYSTEMD_LIBS@ @TOR_LZMA_LIBS@ @TOR_ZSTD_LIBS@ \
+	$(rust_ldadd)
 
 src_test_test_slow_CPPFLAGS = $(src_test_test_CPPFLAGS)
 src_test_test_slow_CFLAGS = $(src_test_test_CFLAGS)
@@ -220,7 +222,8 @@ src_test_bench_LDADD = src/or/libtor.a src/common/libor.a \
 	src/trace/libor-trace.a \
 	@TOR_ZLIB_LIBS@ @TOR_LIB_MATH@ @TOR_LIBEVENT_LIBS@ \
 	@TOR_OPENSSL_LIBS@ @TOR_LIB_WS32@ @TOR_LIB_GDI@ @CURVE25519_LIBS@ \
-	@TOR_SYSTEMD_LIBS@ @TOR_LZMA_LIBS@ @TOR_ZSTD_LIBS@
+	@TOR_SYSTEMD_LIBS@ @TOR_LZMA_LIBS@ @TOR_ZSTD_LIBS@ \
+	$(rust_ldadd)
 
 src_test_test_workqueue_LDFLAGS = @TOR_LDFLAGS_zlib@ @TOR_LDFLAGS_openssl@ \
         @TOR_LDFLAGS_libevent@
@@ -232,7 +235,8 @@ src_test_test_workqueue_LDADD = src/or/libtor-testing.a \
 	src/trace/libor-trace.a \
 	@TOR_ZLIB_LIBS@ @TOR_LIB_MATH@ @TOR_LIBEVENT_LIBS@ \
 	@TOR_OPENSSL_LIBS@ @TOR_LIB_WS32@ @TOR_LIB_GDI@ @CURVE25519_LIBS@ \
-	@TOR_LZMA_LIBS@ @TOR_ZSTD_LIBS@
+	@TOR_LZMA_LIBS@ @TOR_ZSTD_LIBS@ \
+	$(rust_ldadd)
 
 src_test_test_timers_CPPFLAGS = $(src_test_test_CPPFLAGS)
 src_test_test_timers_CFLAGS = $(src_test_test_CFLAGS)
@@ -243,7 +247,8 @@ src_test_test_timers_LDADD = \
 	src/common/libor-crypto-testing.a $(LIBKECCAK_TINY) $(LIBDONNA) \
 	@TOR_ZLIB_LIBS@ @TOR_LIB_MATH@ @TOR_LIBEVENT_LIBS@ \
 	@TOR_OPENSSL_LIBS@ @TOR_LIB_WS32@ @TOR_LIB_GDI@ @CURVE25519_LIBS@ \
-	@TOR_LZMA_LIBS@
+	@TOR_LZMA_LIBS@ \
+	$(rust_ldadd)
 src_test_test_timers_LDFLAGS = $(src_test_test_LDFLAGS)
 
 noinst_HEADERS+= \
@@ -270,7 +275,8 @@ src_test_test_ntor_cl_LDADD = src/or/libtor.a src/common/libor.a \
 	src/trace/libor-trace.a \
 	@TOR_ZLIB_LIBS@ @TOR_LIB_MATH@ \
 	@TOR_OPENSSL_LIBS@ @TOR_LIB_WS32@ @TOR_LIB_GDI@ @CURVE25519_LIBS@ \
-	@TOR_LZMA_LIBS@
+	@TOR_LZMA_LIBS@ \
+	$(rust_ldadd)
 src_test_test_ntor_cl_AM_CPPFLAGS =	       \
 	-I"$(top_srcdir)/src/or"
 
@@ -291,7 +297,8 @@ src_test_test_bt_cl_LDADD = src/common/libor-testing.a \
 	src/common/libor-ctime-testing.a \
 	src/trace/libor-trace.a \
 	@TOR_LIB_MATH@ \
-	@TOR_LIB_WS32@ @TOR_LIB_GDI@
+	@TOR_LIB_WS32@ @TOR_LIB_GDI@ \
+	$(rust_ldadd)
 src_test_test_bt_cl_CFLAGS = $(AM_CFLAGS) $(TEST_CFLAGS)
 src_test_test_bt_cl_CPPFLAGS= $(src_test_AM_CPPFLAGS) $(TEST_CPPFLAGS)
 

src/tools/include.am

@@ -8,7 +8,8 @@ src_tools_tor_resolve_SOURCES = src/tools/tor-resolve.c
 src_tools_tor_resolve_LDFLAGS =
 src_tools_tor_resolve_LDADD = src/common/libor.a \
 	src/common/libor-ctime.a \
-	@TOR_LIB_MATH@ @TOR_LIB_WS32@
+	@TOR_LIB_MATH@ @TOR_LIB_WS32@ \
+	$(rust_ldadd)
 
 if COVERAGE_ENABLED
 src_tools_tor_cov_resolve_SOURCES = src/tools/tor-resolve.c
@@ -26,7 +27,8 @@ src_tools_tor_gencert_LDADD = src/common/libor.a src/common/libor-crypto.a \
 	$(LIBKECCAK_TINY) \
 	$(LIBDONNA) \
 	@TOR_LIB_MATH@ @TOR_ZLIB_LIBS@ @TOR_OPENSSL_LIBS@ \
-    @TOR_LIB_WS32@ @TOR_LIB_GDI@ @CURVE25519_LIBS@
+	@TOR_LIB_WS32@ @TOR_LIB_GDI@ @CURVE25519_LIBS@ \
+	$(rust_ldadd)
 
 if COVERAGE_ENABLED
 src_tools_tor_cov_gencert_SOURCES = src/tools/tor-gencert.c