Allow us to build a semi-dynamic official binary that works back to CentOS 6, at least on x64, and is very fast since we can build it with newer clang or icc.

ext/misc/linux-old-glibc-compat.c

@@ -0,0 +1,18 @@
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+
+__asm__(".symver memcpy,memcpy@GLIBC_2.2.5");
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+extern void *__wrap_memcpy(void *dest,const void *src,size_t n)
+{
+  return memcpy(dest,src,n);
+}
+
+#ifdef __cplusplus
+}
+#endif

make-linux.mk

@@ -71,7 +71,6 @@ ifeq ($(ZT_DEBUG),1)
 	# C25519 in particular is almost UNUSABLE in -O0 even on a 3ghz box!
 node/Salsa20.o node/SHA512.o node/C25519.o node/Poly1305.o: CXXFLAGS=-Wall -O2 -g -pthread $(INCLUDES) $(DEFS)
 else
-	override DEFS+=-D_FORTIFY_SOURCE=2
 	CFLAGS?=-O3 -fstack-protector
 	override CFLAGS+=-Wall -Wno-deprecated -fPIE -pthread $(INCLUDES) -DNDEBUG $(DEFS)
 	CXXFLAGS?=-O3 -fstack-protector
@@ -210,6 +209,12 @@ ifeq ($(ZT_STATIC),1)
 	override LDFLAGS+=-static
 endif
 
+# For building an official semi-static binary on CentOS 7
+ifeq ($(ZT_OFFICIAL),1)
+	CORE_OBJS+=ext/misc/linux-old-glibc-compat.o
+	override LDFLAGS+=-Wl,--wrap=memcpy -static-libstdc++
+endif
+
 # ARM32 hell -- use conservative CFLAGS
 ifeq ($(ZT_ARCHITECTURE),3)
 	ifeq ($(shell if [ -e /usr/bin/dpkg ]; then dpkg --print-architecture; fi),armel)
@@ -254,7 +259,7 @@ libzerotiercore.a:	FORCE
 core: libzerotiercore.a
 
 selftest:	$(CORE_OBJS) $(ONE_OBJS) selftest.o
-	$(CXX) $(CXXFLAGS) $(LDFLAGS) -o zerotier-selftest selftest.o $(CORE_OBJS) $(ONE_OBJS $(LDLIBS)
+	$(CXX) $(CXXFLAGS) $(LDFLAGS) -o zerotier-selftest selftest.o $(CORE_OBJS) $(ONE_OBJS) $(LDLIBS)
 	$(STRIP) zerotier-selftest
 
 zerotier-selftest: selftest
@@ -265,7 +270,7 @@ manpages:	FORCE
 doc:	manpages
 
 clean: FORCE
-	rm -rf *.a *.so *.o node/*.o controller/*.o osdep/*.o service/*.o ext/http-parser/*.o ext/miniupnpc/*.o ext/libnatpmp/*.o $(CORE_OBJS) $(ONE_OBJS) zerotier-one zerotier-idtool zerotier-cli zerotier-selftest build-* ZeroTierOneInstaller-* *.deb *.rpm .depend debian/files debian/zerotier-one*.debhelper debian/zerotier-one.substvars debian/*.log debian/zerotier-one doc/node_modules
+	rm -rf *.a *.so *.o node/*.o controller/*.o osdep/*.o service/*.o ext/http-parser/*.o ext/miniupnpc/*.o ext/libnatpmp/*.o $(CORE_OBJS) $(ONE_OBJS) zerotier-one zerotier-idtool zerotier-cli zerotier-selftest build-* ZeroTierOneInstaller-* *.deb *.rpm .depend debian/files debian/zerotier-one*.debhelper debian/zerotier-one.substvars debian/*.log debian/zerotier-one doc/node_modules ext/misc/*.o
 
 distclean:	clean
 

selftest.cpp

@@ -660,6 +660,7 @@ static int testOther()
 	std::cout << " " << InetAddress("").toString(buf);
 	std::cout << std::endl;
 
+#if 0
 	std::cout << "[other] Benchmarking memcpy... "; std::cout.flush();
 	{
 		unsigned char *bb = (unsigned char *)::malloc(1234567);
@@ -681,6 +682,7 @@ static int testOther()
 		::free((void *)bb);
 		::free((void *)cc);
 	}
+#endif
 
 	std::cout << "[other] Benchmarking ZT_FAST_MEMCPY... "; std::cout.flush();
 	{