fixes #1083 Random number improvements

13 files changed, 376 insertions, 556 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index c13365f4..2789e0bd 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -221,9 +221,6 @@ elseif (CMAKE_SYSTEM_NAME MATCHES "Android")
 elseif (CMAKE_SYSTEM_NAME MATCHES "Darwin")
     add_definitions(-DNNG_PLATFORM_POSIX)
     add_definitions(-DNNG_PLATFORM_DARWIN)
-    # macOS 10.12 and later have getentropy, but the older releases
-    # have ARC4_RANDOM, and that is sufficient to our needs.
-    add_definitions(-DNNG_USE_ARC4RANDOM)
     set(NNG_PLATFORM_POSIX ON)
 
 elseif (CMAKE_SYSTEM_NAME MATCHES "FreeBSD")
@@ -325,7 +322,6 @@ else ()
 
     nng_check_func(lockf NNG_HAVE_LOCKF)
     nng_check_func(flock NNG_HAVE_FLOCK)
-    nng_check_func(getentropy NNG_HAVE_GETENTROPY)
     nng_check_func(getrandom NNG_HAVE_GETRANDOM)
     nng_check_func(arc4random_buf NNG_HAVE_ARC4RANDOM)
 
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index f5e2eca0..1b177aa1 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -1,6 +1,6 @@
 #
+# Copyright 2020 Staysail Systems, Inc. <info@staysail.tech>
 # Copyright 2018 Capitar IT Group BV <info@capitar.com>
-# Copyright 2018 Staysail Systems, Inc. <info@staysail.tech>
 # Copyright (c) 2012-2013 Martin Sustrik  All rights reserved.
 # Copyright (c) 2013 GoPivotal, Inc.  All rights reserved.
 # Copyright (c) 2015-2016 Jack R. Dunaway. All rights reserved.
@@ -24,7 +24,7 @@
 #   IN THE SOFTWARE.
 #
 
-add_library (${PROJECT_NAME}
+add_library(${PROJECT_NAME}
         nng.c
         ${PROJECT_SOURCE_DIR}/include/nng/nng.h)
 
@@ -34,148 +34,145 @@ if (NNG_TESTS)
             ${PROJECT_SOURCE_DIR}/tests/testutil.c
             ${PROJECT_SOURCE_DIR}/tests/testutil.h
             ${PROJECT_SOURCE_DIR}/include/nng/nng.h)
-endif()
-
-set (NNG_SRCS
-
-    core/defs.h
-
-    core/aio.c
-    core/aio.h
-    core/clock.c
-    core/clock.h
-    core/device.c
-    core/device.h
-    core/dialer.c
-    core/dialer.h
-    core/file.c
-    core/file.h
-    core/idhash.c
-    core/idhash.h
-    core/init.c
-    core/init.h
-    core/list.c
-    core/list.h
-    core/listener.c
-    core/listener.h
-    core/lmq.c
-    core/lmq.h
-    core/message.c
-    core/message.h
-    core/msgqueue.c
-    core/msgqueue.h
-    core/nng_impl.h
-    core/options.c
-    core/options.h
-    core/pollable.c
-    core/pollable.h
-    core/panic.c
-    core/panic.h
-    core/pipe.c
-    core/pipe.h
-    core/platform.h
-    core/protocol.c
-    core/protocol.h
-    core/random.c
-    core/random.h
-    core/reap.c
-    core/reap.h
-    core/socket.c
-    core/socket.h
-    core/sockimpl.h
-    core/stats.c
-    core/stats.h
-    core/stream.c
-    core/stream.h
-    core/strs.c
-    core/strs.h
-    core/taskq.c
-    core/taskq.h
-    core/thread.c
-    core/thread.h
-    core/timer.c
-    core/timer.h
-    core/transport.c
-    core/transport.h
-    core/url.c
-    core/url.h
-)
+endif ()
+
+set(NNG_SRCS
+
+        core/defs.h
+
+        core/aio.c
+        core/aio.h
+        core/clock.c
+        core/clock.h
+        core/device.c
+        core/device.h
+        core/dialer.c
+        core/dialer.h
+        core/file.c
+        core/file.h
+        core/idhash.c
+        core/idhash.h
+        core/init.c
+        core/init.h
+        core/list.c
+        core/list.h
+        core/listener.c
+        core/listener.h
+        core/lmq.c
+        core/lmq.h
+        core/message.c
+        core/message.h
+        core/msgqueue.c
+        core/msgqueue.h
+        core/nng_impl.h
+        core/options.c
+        core/options.h
+        core/pollable.c
+        core/pollable.h
+        core/panic.c
+        core/panic.h
+        core/pipe.c
+        core/pipe.h
+        core/platform.h
+        core/protocol.c
+        core/protocol.h
+        core/reap.c
+        core/reap.h
+        core/socket.c
+        core/socket.h
+        core/sockimpl.h
+        core/stats.c
+        core/stats.h
+        core/stream.c
+        core/stream.h
+        core/strs.c
+        core/strs.h
+        core/taskq.c
+        core/taskq.h
+        core/thread.c
+        core/thread.h
+        core/timer.c
+        core/timer.h
+        core/transport.c
+        core/transport.h
+        core/url.c
+        core/url.h
+        )
 
 if (NNG_PLATFORM_POSIX)
-    find_package (Threads REQUIRED)
+    find_package(Threads REQUIRED)
     list(APPEND NNG_LIBS Threads::Threads)
 
-    set (NNG_SRCS ${NNG_SRCS}
-        platform/posix/posix_impl.h
-        platform/posix/posix_aio.h
-        platform/posix/posix_ipc.h
-        platform/posix/posix_config.h
-        platform/posix/posix_pollq.h
-        platform/posix/posix_tcp.h
-
-        platform/posix/posix_alloc.c
-        platform/posix/posix_atomic.c
-        platform/posix/posix_clock.c
-        platform/posix/posix_debug.c
-        platform/posix/posix_file.c
-        platform/posix/posix_ipcconn.c
-        platform/posix/posix_ipcdial.c
-        platform/posix/posix_ipclisten.c
-        platform/posix/posix_pipe.c
-        platform/posix/posix_rand.c
-        platform/posix/posix_resolv_gai.c
-        platform/posix/posix_sockaddr.c
-        platform/posix/posix_tcpconn.c
-        platform/posix/posix_tcpdial.c
-        platform/posix/posix_tcplisten.c
-        platform/posix/posix_thread.c
-        platform/posix/posix_udp.c
-    )
+    set(NNG_SRCS ${NNG_SRCS}
+            platform/posix/posix_impl.h
+            platform/posix/posix_aio.h
+            platform/posix/posix_ipc.h
+            platform/posix/posix_config.h
+            platform/posix/posix_pollq.h
+            platform/posix/posix_tcp.h
+
+            platform/posix/posix_alloc.c
+            platform/posix/posix_atomic.c
+            platform/posix/posix_clock.c
+            platform/posix/posix_debug.c
+            platform/posix/posix_file.c
+            platform/posix/posix_ipcconn.c
+            platform/posix/posix_ipcdial.c
+            platform/posix/posix_ipclisten.c
+            platform/posix/posix_pipe.c
+            platform/posix/posix_resolv_gai.c
+            platform/posix/posix_sockaddr.c
+            platform/posix/posix_tcpconn.c
+            platform/posix/posix_tcpdial.c
+            platform/posix/posix_tcplisten.c
+            platform/posix/posix_thread.c
+            platform/posix/posix_udp.c
+            )
 
     if (NNG_HAVE_PORT_CREATE)
-        set (NNG_SRCS ${NNG_SRCS}
-            platform/posix/posix_pollq_port.c
-        )
+        set(NNG_SRCS ${NNG_SRCS} platform/posix/posix_pollq_port.c)
     elseif (NNG_HAVE_KQUEUE)
-        set (NNG_SRCS ${NNG_SRCS}
-            platform/posix/posix_pollq_kqueue.c
-        )
+        set(NNG_SRCS ${NNG_SRCS} platform/posix/posix_pollq_kqueue.c)
     elseif (NNG_HAVE_EPOLL AND NNG_HAVE_EVENTFD)
-        set (NNG_SRCS ${NNG_SRCS}
-            platform/posix/posix_pollq_epoll.c
-        )
-    else()
-        set (NNG_SRCS ${NNG_SRCS}
-            platform/posix/posix_pollq_poll.c
-        )
-    endif()
-endif()
+        set(NNG_SRCS ${NNG_SRCS} platform/posix/posix_pollq_epoll.c)
+    else ()
+        set(NNG_SRCS ${NNG_SRCS} platform/posix/posix_pollq_poll.c)
+    endif ()
+
+    if (NNG_HAVE_ARC4RANDOM)
+        set(NNG_SRCS ${NNG_SRCS} platform/posix/posix_rand_arc4random.c)
+    elseif (NNG_HAVE_GETRANDOM)
+        set(NNG_SRCS ${NNG_SRCS} platform/posix/posix_rand_getrandom.c)
+    else ()
+        set(NNG_SRCS ${NNG_SRCS} platform/posix/posix_rand_urandom.c)
+    endif ()
+endif ()
 
 if (NNG_PLATFORM_WINDOWS)
-    set (NNG_SRCS ${NNG_SRCS}
-        platform/windows/win_impl.h
-        platform/windows/win_ipc.h
-        platform/windows/win_tcp.h
-
-        platform/windows/win_clock.c
-        platform/windows/win_debug.c
-        platform/windows/win_file.c
-        platform/windows/win_io.c
-        platform/windows/win_ipcconn.c
-        platform/windows/win_ipcdial.c
-        platform/windows/win_ipclisten.c
-        platform/windows/win_pipe.c
-        platform/windows/win_rand.c
-        platform/windows/win_resolv.c
-        platform/windows/win_sockaddr.c
-        platform/windows/win_tcp.c
-        platform/windows/win_tcpconn.c
-        platform/windows/win_tcpdial.c
-        platform/windows/win_tcplisten.c
-        platform/windows/win_thread.c
-        platform/windows/win_udp.c
-        )
-endif()
+    set(NNG_SRCS ${NNG_SRCS}
+            platform/windows/win_impl.h
+            platform/windows/win_ipc.h
+            platform/windows/win_tcp.h
+
+            platform/windows/win_clock.c
+            platform/windows/win_debug.c
+            platform/windows/win_file.c
+            platform/windows/win_io.c
+            platform/windows/win_ipcconn.c
+            platform/windows/win_ipcdial.c
+            platform/windows/win_ipclisten.c
+            platform/windows/win_pipe.c
+            platform/windows/win_rand.c
+            platform/windows/win_resolv.c
+            platform/windows/win_sockaddr.c
+            platform/windows/win_tcp.c
+            platform/windows/win_tcpconn.c
+            platform/windows/win_tcpdial.c
+            platform/windows/win_tcplisten.c
+            platform/windows/win_thread.c
+            platform/windows/win_udp.c
+            )
+endif ()
 
 
 add_subdirectory(compat/nanomsg)
@@ -207,8 +204,8 @@ include_directories(AFTER SYSTEM ${PROJECT_SOURCE_DIR}/src ${NNG_INCS})
 
 add_definitions(${NNG_DEFS})
 
-foreach(_PKG IN ITEMS ${NNG_PKGS})
-	find_package(${_PKG} REQUIRED)
+foreach (_PKG IN ITEMS ${NNG_PKGS})
+    find_package(${_PKG} REQUIRED)
 endforeach ()
 
 # Library
@@ -216,10 +213,10 @@ target_sources(${PROJECT_NAME} PRIVATE ${NNG_SRCS})
 
 if (NNG_TESTS)
     target_sources(${PROJECT_NAME}_testlib PRIVATE ${NNG_SRCS})
-    target_link_libraries (${PROJECT_NAME}_testlib PUBLIC ${NNG_LIBS})
+    target_link_libraries(${PROJECT_NAME}_testlib PUBLIC ${NNG_LIBS})
     target_compile_definitions(${PROJECT_NAME}_testlib PUBLIC NNG_STATIC_LIB NNG_TEST_LIB)
-    target_include_directories (${PROJECT_NAME}_testlib PUBLIC ${PROJECT_SOURCE_DIR}/include)
-endif()
+    target_include_directories(${PROJECT_NAME}_testlib PUBLIC ${PROJECT_SOURCE_DIR}/include)
+endif ()
 
 # When building shared libraries we prefer to suppress default symbol
 # visibility, so that only the symbols that should be exposed in the
@@ -229,55 +226,55 @@ if (BUILD_SHARED_LIBS)
     if (NNG_HIDDEN_VISIBILITY)
         target_compile_definitions(${PROJECT_NAME} PRIVATE -DNNG_HIDDEN_VISIBILITY)
         set_target_properties(${PROJECT_NAME} PROPERTIES C_VISIBILITY_PRESET hidden)
-    endif()
-else()
+    endif ()
+else ()
     target_compile_definitions(${PROJECT_NAME} PUBLIC -DNNG_STATIC_LIB)
-endif()
+endif ()
 
-set_target_properties (${PROJECT_NAME}
-	PROPERTIES SOVERSION ${NNG_ABI_SOVERSION} VERSION "${NNG_ABI_VERSION}")
+set_target_properties(${PROJECT_NAME}
+        PROPERTIES SOVERSION ${NNG_ABI_SOVERSION} VERSION "${NNG_ABI_VERSION}")
 
 # Set library outputs same as top-level project binary outputs
-set_target_properties (${PROJECT_NAME}
-	PROPERTIES RUNTIME_OUTPUT_DIRECTORY ${PROJECT_BINARY_DIR})
-set_target_properties (${PROJECT_NAME}
-	PROPERTIES LIBRARY_OUTPUT_DIRECTORY ${PROJECT_BINARY_DIR})
-set_target_properties (${PROJECT_NAME}
-	PROPERTIES ARCHIVE_OUTPUT_DIRECTORY ${PROJECT_BINARY_DIR})
-
-set_target_properties (${PROJECT_NAME} ${PROJECT_NAME}
-	PROPERTIES FRAMEWORK OFF)
-
-target_link_libraries (${PROJECT_NAME} PRIVATE ${NNG_LIBS})
-
-target_include_directories (${PROJECT_NAME} INTERFACE $<INSTALL_INTERFACE:include>
-$<BUILD_INTERFACE:${PROJECT_SOURCE_DIR}/include>)
-
-target_include_directories (${PROJECT_NAME} PRIVATE ${PROJECT_SOURCE_DIR}/include)
-
-install (TARGETS ${PROJECT_NAME}
-    EXPORT ${PROJECT_NAME}-target
-    FRAMEWORK DESTINATION ${CMAKE_INSTALL_LIBDIR} COMPONENT Library
-    ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR} COMPONENT Library
-    LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR} COMPONENT Library
-    RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR} COMPONENT Tools
-)
-
-install (EXPORT ${PROJECT_NAME}-target
-    FILE ${PROJECT_NAME}-targets.cmake
-    NAMESPACE nng::
-    DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake/${PROJECT_NAME}
-    COMPONENT Library
-)
-
-export (EXPORT ${PROJECT_NAME}-target
-    FILE ${CMAKE_CURRENT_BINARY_DIR}/${PROJECT_NAME}-targets.cmake
-    NAMESPACE nng::)
+set_target_properties(${PROJECT_NAME}
+        PROPERTIES RUNTIME_OUTPUT_DIRECTORY ${PROJECT_BINARY_DIR})
+set_target_properties(${PROJECT_NAME}
+        PROPERTIES LIBRARY_OUTPUT_DIRECTORY ${PROJECT_BINARY_DIR})
+set_target_properties(${PROJECT_NAME}
+        PROPERTIES ARCHIVE_OUTPUT_DIRECTORY ${PROJECT_BINARY_DIR})
+
+set_target_properties(${PROJECT_NAME} ${PROJECT_NAME}
+        PROPERTIES FRAMEWORK OFF)
+
+target_link_libraries(${PROJECT_NAME} PRIVATE ${NNG_LIBS})
+
+target_include_directories(${PROJECT_NAME} INTERFACE $<INSTALL_INTERFACE:include>
+        $<BUILD_INTERFACE:${PROJECT_SOURCE_DIR}/include>)
+
+target_include_directories(${PROJECT_NAME} PRIVATE ${PROJECT_SOURCE_DIR}/include)
+
+install(TARGETS ${PROJECT_NAME}
+        EXPORT ${PROJECT_NAME}-target
+        FRAMEWORK DESTINATION ${CMAKE_INSTALL_LIBDIR} COMPONENT Library
+        ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR} COMPONENT Library
+        LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR} COMPONENT Library
+        RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR} COMPONENT Tools
+        )
+
+install(EXPORT ${PROJECT_NAME}-target
+        FILE ${PROJECT_NAME}-targets.cmake
+        NAMESPACE nng::
+        DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake/${PROJECT_NAME}
+        COMPONENT Library
+        )
+
+export(EXPORT ${PROJECT_NAME}-target
+        FILE ${CMAKE_CURRENT_BINARY_DIR}/${PROJECT_NAME}-targets.cmake
+        NAMESPACE nng::)
 
 # Install the header files.
 install(DIRECTORY ../include/nng
-    DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}
-    COMPONENT Headers)
+        DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}
+        COMPONENT Headers)
 
 # Promote settings to parent
 set(NNG_LIBS ${NNG_LIBS} PARENT_SCOPE)
@@ -300,13 +297,13 @@ set(version_config "${CMAKE_CURRENT_BINARY_DIR}/${PROJECT_NAME}-config-version.c
 set(project_config "${CMAKE_CURRENT_BINARY_DIR}/${PROJECT_NAME}-config.cmake")
 
 write_basic_package_version_file("${version_config}"
-    VERSION ${NNG_PACKAGE_VERSION}
-    COMPATIBILITY SameMajorVersion
-)
+        VERSION ${NNG_PACKAGE_VERSION}
+        COMPATIBILITY SameMajorVersion
+        )
 configure_package_config_file(${PROJECT_SOURCE_DIR}/cmake/${PROJECT_NAME}-config.cmake.in "${project_config}"
-    INSTALL_DESTINATION "${CMAKE_INSTALL_LIBDIR}/cmake/${PROJECT_NAME}"
-    PATH_VARS INCLUDE_INSTALL_DIRS)
+        INSTALL_DESTINATION "${CMAKE_INSTALL_LIBDIR}/cmake/${PROJECT_NAME}"
+        PATH_VARS INCLUDE_INSTALL_DIRS)
 
 install(FILES "${project_config}" "${version_config}"
-    DESTINATION "${CMAKE_INSTALL_LIBDIR}/cmake/${PROJECT_NAME}"
-    COMPONENT Library)
+        DESTINATION "${CMAKE_INSTALL_LIBDIR}/cmake/${PROJECT_NAME}"
+        COMPONENT Library)
diff --git a/src/core/init.c b/src/core/init.c
index 60736fb7..4749516f 100644
--- a/src/core/init.c
+++ b/src/core/init.c
@@ -1,5 +1,5 @@
 //
-// Copyright 2018 Staysail Systems, Inc. <info@staysail.tech>
+// Copyright 2020 Staysail Systems, Inc. <info@staysail.tech>
 // Copyright 2018 Capitar IT Group BV <info@capitar.com>
 //
 // This software is supplied under the terms of the MIT License, a
@@ -32,7 +32,6 @@ nni_init_helper(void)
 	    ((rv = nni_reap_sys_init()) != 0) ||
 	    ((rv = nni_timer_sys_init()) != 0) ||
 	    ((rv = nni_aio_sys_init()) != 0) ||
-	    ((rv = nni_random_sys_init()) != 0) ||
 	    ((rv = nni_sock_sys_init()) != 0) ||
 	    ((rv = nni_listener_sys_init()) != 0) ||
 	    ((rv = nni_dialer_sys_init()) != 0) ||
@@ -77,7 +76,6 @@ nni_fini(void)
 	nni_listener_sys_fini();
 	nni_sock_sys_fini();
 	nni_reap_drain();
-	nni_random_sys_fini();
 	nni_aio_sys_fini();
 	nni_timer_sys_fini();
 	nni_taskq_sys_fini();
diff --git a/src/core/nng_impl.h b/src/core/nng_impl.h
index 0dcc976f..cfcd0e08 100644
--- a/src/core/nng_impl.h
+++ b/src/core/nng_impl.h
@@ -40,7 +40,6 @@
 #include "core/panic.h"
 #include "core/pollable.h"
 #include "core/protocol.h"
-#include "core/random.h"
 #include "core/reap.h"
 #include "core/stats.h"
 #include "core/stream.h"
diff --git a/src/core/platform.h b/src/core/platform.h
index b56f9a68..355ef7eb 100644
--- a/src/core/platform.h
+++ b/src/core/platform.h
@@ -208,11 +208,8 @@ extern void nni_plat_sleep(nni_duration);
 // Entropy Support
 //
 
-// nni_plat_seed_prng seeds the PRNG subsystem.  The specified number
-// of bytes of entropy should be stashed.  When possible, cryptographic
-// quality entropy sources should be used.  Note that today we prefer
-// to seed up to 256 bytes of data.
-extern void nni_plat_seed_prng(void *, size_t);
+// nni_random returns a cryptographically secure random uint32.
+uint32_t nni_random(void);
 
 // nni_plat_init is called to allow the platform the chance to
 // do any necessary initialization.  This routine MUST be idempotent,
diff --git a/src/core/random.c b/src/core/random.c
deleted file mode 100644
index 2d899f21..00000000
--- a/src/core/random.c
+++ /dev/null
@@ -1,202 +0,0 @@
-//
-// Copyright 2018 Staysail Systems, Inc. <info@staysail.tech>
-// Copyright 2018 Capitar IT Group BV <info@capitar.com>
-//
-// This software is supplied under the terms of the MIT License, a
-// copy of which should be located in the distribution where this
-// file was obtained (LICENSE.txt).  A copy of the license may also be
-// found online at https://opensource.org/licenses/MIT.
-//
-
-#include "core/nng_impl.h"
-
-// This is ISAAC, a (reputedly) cryptographically secure PRNG that is also
-// quite efficient.  While the particular adjustments to fit in our code
-// base are under our copyright, the actual algorithm itself, as well as
-// sample implementations, are part of the public domain.  See this:
-// http://www.burtleburtle.net/bob/c/readable.c
-//
-// Our changes include making this code thread safe/reentrant, and naming
-// and style changes, to fit C99.
-
-typedef struct {
-	// the rsl is the actual results, and the randcnt is the length
-	// of the results.
-	uint32_t randrsl[256];
-	uint32_t randcnt;
-
-	// lock to protect concurrent access
-	nni_mtx mx;
-
-	// more or less internal state
-	uint32_t mm[256];
-	uint32_t aa;
-	uint32_t bb;
-	uint32_t cc;
-} nni_isaac_ctx;
-
-static void
-nni_isaac(nni_isaac_ctx *ctx)
-{
-	ctx->cc++;          // cc incremented once per 256 results
-	ctx->bb += ctx->cc; // then combined with bb
-
-	for (uint32_t i = 0; i < 256; ++i) {
-		uint32_t x = ctx->mm[i];
-		uint32_t y;
-		switch (i % 4) {
-		case 0:
-			ctx->aa ^= (ctx->aa << 13);
-			break;
-		case 1:
-			ctx->aa ^= (ctx->aa >> 6);
-			break;
-		case 2:
-			ctx->aa ^= (ctx->aa << 2);
-			break;
-		case 3:
-			ctx->aa ^= (ctx->aa >> 16);
-			break;
-		}
-		ctx->aa += ctx->mm[(i + 128) % 256];
-		ctx->mm[i] = y  = ctx->mm[(x >> 2) % 256] + ctx->aa + ctx->bb;
-		ctx->randrsl[i] = ctx->bb = ctx->mm[(y >> 10) % 256] + x;
-
-		// Note that bits 2..9 are chosen from x but 10..17 are chosen
-		// from y.  The only important thing here is that 2..9 and
-		// 10..17 don't overlap.  2..9 and 10..17 were then chosen
-		// for speed in the optimized version (rand.c)
-
-		// See http://burtleburtle.net/bob/rand/isaac.html
-		// for further explanations and analysis.
-	}
-}
-
-// if (flag!=0), then use the contents of randrsl[] to initialize mm[].
-#define nni_isaac_mix(a, b, c, d, e, f, g, h) \
-	{                                     \
-		a ^= b << 11;                 \
-		d += a;                       \
-		b += c;                       \
-		b ^= c >> 2;                  \
-		e += b;                       \
-		c += d;                       \
-		c ^= d << 8;                  \
-		f += c;                       \
-		d += e;                       \
-		d ^= e >> 16;                 \
-		g += d;                       \
-		e += f;                       \
-		e ^= f << 10;                 \
-		h += e;                       \
-		f += g;                       \
-		f ^= g >> 4;                  \
-		a += f;                       \
-		g += h;                       \
-		g ^= h << 8;                  \
-		b += g;                       \
-		h += a;                       \
-		h ^= a >> 9;                  \
-		c += h;                       \
-		a += b;                       \
-	}
-
-static void
-nni_isaac_randinit(nni_isaac_ctx *ctx, int flag)
-{
-	int      i;
-	uint32_t a, b, c, d, e, f, g, h;
-
-	ctx->aa = ctx->bb = ctx->cc = 0;
-	a = b = c = d = e = f = g = h = 0x9e3779b9; // the golden ratio
-
-	for (i = 0; i < 4; ++i) { // scramble it
-		nni_isaac_mix(a, b, c, d, e, f, g, h);
-	}
-
-	for (i = 0; i < 256; i += 8) { // fill in mm[] with messy stuff
-		if (flag) {            // use all the information in the seed
-			a += ctx->randrsl[i];
-			b += ctx->randrsl[i + 1];
-			c += ctx->randrsl[i + 2];
-			d += ctx->randrsl[i + 3];
-			e += ctx->randrsl[i + 4];
-			f += ctx->randrsl[i + 5];
-			g += ctx->randrsl[i + 6];
-			h += ctx->randrsl[i + 7];
-		}
-		nni_isaac_mix(a, b, c, d, e, f, g, h);
-		ctx->mm[i]     = a;
-		ctx->mm[i + 1] = b;
-		ctx->mm[i + 2] = c;
-		ctx->mm[i + 3] = d;
-		ctx->mm[i + 4] = e;
-		ctx->mm[i + 5] = f;
-		ctx->mm[i + 6] = g;
-		ctx->mm[i + 7] = h;
-	}
-
-	if (flag) {
-		// do a second pass to make all of the seed affect all of mm
-		for (i = 0; i < 256; i += 8) {
-			a += ctx->mm[i];
-			b += ctx->mm[i + 1];
-			c += ctx->mm[i + 2];
-			d += ctx->mm[i + 3];
-			e += ctx->mm[i + 4];
-			f += ctx->mm[i + 5];
-			g += ctx->mm[i + 6];
-			h += ctx->mm[i + 7];
-			nni_isaac_mix(a, b, c, d, e, f, g, h);
-			ctx->mm[i]     = a;
-			ctx->mm[i + 1] = b;
-			ctx->mm[i + 2] = c;
-			ctx->mm[i + 3] = d;
-			ctx->mm[i + 4] = e;
-			ctx->mm[i + 5] = f;
-			ctx->mm[i + 6] = g;
-			ctx->mm[i + 7] = h;
-		}
-	}
-
-	nni_isaac(ctx);     // fill in the first set of results
-	ctx->randcnt = 256; // prepare to use the first set of results
-}
-
-static nni_isaac_ctx nni_random_ctx;
-
-int
-nni_random_sys_init(void)
-{
-	// minimally, grab the system clock
-	nni_isaac_ctx *ctx = &nni_random_ctx;
-
-	nni_mtx_init(&ctx->mx);
-	nni_plat_seed_prng(ctx->randrsl, sizeof(ctx->randrsl));
-	nni_isaac_randinit(ctx, 1);
-	return (0);
-}
-
-uint32_t
-nni_random(void)
-{
-	uint32_t       rv;
-	nni_isaac_ctx *ctx = &nni_random_ctx;
-
-	nni_mtx_lock(&ctx->mx);
-	if (ctx->randcnt < 1) {
-		nni_isaac(ctx);
-		ctx->randcnt = 256;
-	}
-	ctx->randcnt--;
-	rv = ctx->randrsl[ctx->randcnt];
-	nni_mtx_unlock(&ctx->mx);
-
-	return (rv);
-}
-
-void
-nni_random_sys_fini(void)
-{
-	nni_mtx_fini(&nni_random_ctx.mx);
-}
diff --git a/src/core/random.h b/src/core/random.h
deleted file mode 100644
index 33229b09..00000000
--- a/src/core/random.h
+++ /dev/null
@@ -1,26 +0,0 @@
-//
-// Copyright 2017 Garrett D'Amore <garrett@damore.org>
-//
-// This software is supplied under the terms of the MIT License, a
-// copy of which should be located in the distribution where this
-// file was obtained (LICENSE.txt).  A copy of the license may also be
-// found online at https://opensource.org/licenses/MIT.
-//
-
-#ifndef CORE_RANDOM_H
-#define CORE_RANDOM_H
-
-// nni_random_sys_init initializes the pRNG subsystem.  This includes obtaining
-// suitable seeding material from the platform.
-extern int nni_random_sys_init(void);
-
-// nni_random_sys_fini destroys the pRNG subsystem.
-extern void nni_random_sys_fini(void);
-
-// nni_random returns a random 32-bit integer.  Note that this routine is
-// thread-safe/reentrant.  The pRNG is very robust, should be of crypto
-// quality.  However, its usefulness for cryptography will be determined
-// by the quality of the seeding material provided by the platform.
-extern uint32_t nni_random(void);
-
-#endif // CORE_RANDOM_H
diff --git a/src/platform/posix/posix_rand.c b/src/platform/posix/posix_rand.c
deleted file mode 100644
index 2b704e2f..00000000
--- a/src/platform/posix/posix_rand.c
+++ /dev/null
@@ -1,88 +0,0 @@
-//
-// Copyright 2018 Staysail Systems, Inc. <info@staysail.tech>
-// Copyright 2018 Capitar IT Group BV <info@capitar.com>
-//
-// This software is supplied under the terms of the MIT License, a
-// copy of which should be located in the distribution where this
-// file was obtained (LICENSE.txt).  A copy of the license may also be
-// found online at https://opensource.org/licenses/MIT.
-//
-
-// POSIX clock stuff.
-#include "core/nng_impl.h"
-
-#ifdef NNG_PLATFORM_POSIX
-
-#include <errno.h>
-#include <fcntl.h>
-#include <stdlib.h>
-#include <string.h>
-#include <sys/types.h>
-#include <sys/utsname.h>
-#include <time.h>
-#include <unistd.h>
-
-#if defined(NNG_USE_GETRANDOM)
-#include <linux/random.h>
-#elif defined(NNG_USE_GETENTROPY)
-#include <sys/random.h>
-#endif
-
-// This structure represents the very barest minimum that we can use as
-// a source of entropy.  We mix these into our initial entropy, but really
-// really really you want to have more data than this available, especially
-// for cryptographic applications.
-struct nni_plat_prng_x {
-	nni_time       now;
-	pid_t          pid;
-	uid_t          uid;
-	struct utsname uts;
-};
-
-void
-nni_plat_seed_prng(void *buf, size_t bufsz)
-{
-	struct nni_plat_prng_x x;
-	size_t                 i;
-
-	memset(buf, 0, bufsz);
-
-#if defined(NNG_USE_GETRANDOM)
-	// Latest Linux has a nice API here.
-	(void) getrandom(buf, bufsz, 0);
-#elif defined(NNG_USE_GETENTROPY)
-	// Modern BSD systems prefer this, but can only generate 256 bytes
-	(void) getentropy(buf, bufsz > 256 ? 256 : 0);
-#elif defined(NNG_USE_ARC4RANDOM)
-	// This uses BSD style pRNG seeded from the kernel in libc.
-	(void) arc4random_buf(buf, bufsz);
-#elif defined(NNG_USE_DEVURANDOM)
-	// The historic /dev/urandom device.  This is not as a good as
-	// a system call, since file descriptor attacks are possible,
-	// and it may need special permissions.  We choose /dev/urandom
-	// over /dev/random to avoid diminishing the system entropy.
-	int fd;
-
-	if ((fd = open("/dev/urandom", O_RDONLY)) >= 0) {
-		(void) read(fd, buf, bufsz);
-		(void) close(fd);
-	}
-#endif
-
-	// As a special extra guard, let's mixin the data from the
-	// following system calls.  This ensures that even on the most
-	// limited of systems, we have at least *some* level of randomness.
-	// The mixing is done in a way to avoid diminishing entropy we may
-	// have already collected.
-	memset(&x, 0, sizeof(x)); // satisfy valgrind
-	x.now = nni_clock();
-	x.pid = getpid();
-	x.uid = getuid();
-	uname(&x.uts);
-
-	for (i = 0; (i < bufsz) && (i < sizeof(x)); i++) {
-		((uint8_t *) buf)[i] ^= ((uint8_t *) &x)[i];
-	}
-}
-
-#endif // NNG_PLATFORM_POSIX
diff --git a/src/platform/posix/posix_rand_arc4random.c b/src/platform/posix/posix_rand_arc4random.c
new file mode 100644
index 00000000..a3cc265b
--- /dev/null
+++ b/src/platform/posix/posix_rand_arc4random.c
@@ -0,0 +1,24 @@
+//
+// Copyright 2020 Staysail Systems, Inc. <info@staysail.tech>
+//
+// This software is supplied under the terms of the MIT License, a
+// copy of which should be located in the distribution where this
+// file was obtained (LICENSE.txt).  A copy of the license may also be
+// found online at https://opensource.org/licenses/MIT.
+//
+
+// arc4random is the preferred source of cryptographic random numbers
+// on any platform where it is found.
+#include <stdlib.h>
+
+#include "core/nng_impl.h"
+
+#ifdef NNG_HAVE_ARC4RANDOM
+
+uint32_t
+nni_random(void)
+{
+	return (arc4random());
+}
+
+#endif
\ No newline at end of file
diff --git a/src/platform/posix/posix_rand_getrandom.c b/src/platform/posix/posix_rand_getrandom.c
new file mode 100644
index 00000000..489b2c76
--- /dev/null
+++ b/src/platform/posix/posix_rand_getrandom.c
@@ -0,0 +1,40 @@
+//
+// Copyright 2020 Staysail Systems, Inc. <info@staysail.tech>
+//
+// This software is supplied under the terms of the MIT License, a
+// copy of which should be located in the distribution where this
+// file was obtained (LICENSE.txt).  A copy of the license may also be
+// found online at https://opensource.org/licenses/MIT.
+//
+
+// getrandom is not as nice as arc4random, but on platforms where it
+// exists and arc4random does not, we should use it.
+//
+// getrandom will block only if the urandom device is not seeded yet.
+// That can only happen during very early boot (earlier than we should
+// normally be running.  This is the only time it can fail with correct
+// arguments, and then only if it is interrupted with a signal.
+
+#include <sys/random.h>
+
+#include "core/nng_impl.h"
+
+#ifdef NNG_HAVE_GETRANDOM
+
+uint32_t
+nni_random(void)
+{
+	uint32_t val;
+
+	// Documentation claims that as long as we are not using
+	// GRND_RANDOM and buflen < 256, this should never fail.
+	// The exception here is that we could fail if for some
+	// reason we got a signal while blocked at very early boot
+	// (i.e. /dev/urandom was not yet seeded).
+	if (getrandom(&val, sizeof(val), 0) != sizeof(val)) {
+		nni_panic("getrandom failed");
+	}
+	return (val);
+}
+
+#endif
\ No newline at end of file
diff --git a/src/platform/posix/posix_rand_urandom.c b/src/platform/posix/posix_rand_urandom.c
new file mode 100644
index 00000000..32ea6a51
--- /dev/null
+++ b/src/platform/posix/posix_rand_urandom.c
@@ -0,0 +1,58 @@
+//
+// Copyright 2020 Staysail Systems, Inc. <info@staysail.tech>
+//
+// This software is supplied under the terms of the MIT License, a
+// copy of which should be located in the distribution where this
+// file was obtained (LICENSE.txt).  A copy of the license may also be
+// found online at https://opensource.org/licenses/MIT.
+//
+
+#include <fcntl.h>
+#include <pthread.h>
+#include <stdint.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include "core/nng_impl.h"
+
+// The historic /dev/urandom device.  This is not as a good as
+// a system call, since file descriptor attacks are possible,  and it may
+// need special permissions. Modern advice is to always use /dev/urandom
+// unless you have very particular reasons for doing otherwise.
+// If you're in this code base, you're probably on either an ancient OS,
+// or one of the off-beat ones that hasn't updated for support with
+// arc4random or getrandom.
+
+// We could use ISAAC or something like that to seed it only once,
+// but instead we just keep our file descriptor open.  This will have
+// the apparent effect of leaking these file descriptors across fork.
+
+static int             urandom_fd   = -1;
+static pthread_mutex_t urandom_lock = PTHREAD_MUTEX_INITIALIZER;
+
+#ifndef O_CLOEXEC
+#define O_CLOEXEC 0u
+#endif
+
+uint32_t
+nni_random(void)
+{
+	int      fd;
+	uint32_t val;
+
+	(void) pthread_mutex_lock(&urandom_lock);
+	if ((fd = urandom_fd) == -1) {
+		if ((fd = open("/dev/urandom", O_RDONLY | O_CLOEXEC)) < 0) {
+			(void) pthread_mutex_unlock(&urandom_lock);
+			nni_panic("failed to open /dev/urandom");
+		}
+		urandom_fd = fd;
+	}
+	(void) pthread_mutex_unlock(&urandom_lock);
+
+	if (read(fd, &val, sizeof(val)) != sizeof(val)) {
+		nni_panic("failed reading /dev/urandom");
+	}
+	return (val);
+}
\ No newline at end of file
diff --git a/src/platform/windows/win_rand.c b/src/platform/windows/win_rand.c
index afe703ef..21568a81 100644
--- a/src/platform/windows/win_rand.c
+++ b/src/platform/windows/win_rand.c
@@ -1,5 +1,5 @@
 //
-// Copyright 2017 Garrett D'Amore <garrett@damore.org>
+// Copyright 2020 Staysail Systems, Inc. <info@staysail.tech>
 //
 // This software is supplied under the terms of the MIT License, a
 // copy of which should be located in the distribution where this
@@ -11,22 +11,24 @@
 
 #ifdef NNG_PLATFORM_WINDOWS
 
+#ifndef _CRT_RAND_S
+#define _CRT_RAND_S
+#endif
+
 #include <stdlib.h>
 
-void
-nni_plat_seed_prng(void *buf, size_t bufsz)
+uint32_t
+nni_random(void)
 {
 	unsigned val;
 
-	// The rand_s routine uses RtlGenRandom to get high quality
-	// pseudo random numbers (i.e. numbers that should be good enough
-	// for use with crypto keying.)
-	while (bufsz > sizeof(val)) {
-		rand_s(&val);
-		memcpy(buf, &val, sizeof(val));
-		buf = (((char *) buf) + sizeof(val));
-		bufsz -= sizeof(val);
-	}
+	// rand_s is claimed by Microsoft to generate cryptographically
+	// secure numbers.  It also is claimed that this will only fail
+	// for EINVAL if val is NULL (not the case here).  Other error
+	// conditions might be possible, but we have no way to tell.
+	// For now we just ignore that possibility.
+	rand_s(&val);
+	return ((uint32_t)val);
 }
 
-#endif // NNG_PLATFORM_WINDOWS
+#endif // NNG_PLATFORM_WINDOWS
\ No newline at end of file
diff --git a/tests/platform.c b/tests/platform.c
index 7546fa7f..fc9eb210 100644
--- a/tests/platform.c
+++ b/tests/platform.c
@@ -66,10 +66,10 @@ test_clock(void)
 	TEST_CHECK(usdelta >= 200);
 	TEST_CHECK(usdelta < 500); // increased tolerance for CIs
 	if (msdelta > usdelta) {
-                TEST_CHECK((msdelta - usdelta) < 50);
+		TEST_CHECK((msdelta - usdelta) < 50);
 	} else {
-                TEST_CHECK((usdelta - msdelta) < 50);
-        }
+		TEST_CHECK((usdelta - msdelta) < 50);
+	}
 }
 
 void
@@ -108,40 +108,65 @@ test_thread(void)
 	nng_thread_destroy(thr);
 	TEST_CHECK(aa.cnt == 1);
 
-        nng_cv_free(aa.cv);
+	nng_cv_free(aa.cv);
 	nng_mtx_free(aa.mx);
 }
 
 void
 test_condvar(void)
 {
-        nng_thread *  thr;
-        int           rv;
-        struct addarg aa;
-
-        TEST_CHECK(nng_mtx_alloc(&aa.mx) == 0);
-        TEST_CHECK(nng_cv_alloc(&aa.cv, aa.mx) == 0);
-        aa.cnt = 0;
-
-        TEST_CHECK((rv = nng_thread_create(&thr, add, &aa)) == 0);
-
-        nng_mtx_lock(aa.mx);
-        while (aa.cnt == 0) {
-                nng_cv_wait(aa.cv);
-        }
-        nng_mtx_unlock(aa.mx);
-        nng_thread_destroy(thr);
-        TEST_CHECK(aa.cnt == 1);
-
-        nng_cv_free(aa.cv);
-        nng_mtx_free(aa.mx);
+	nng_thread *  thr;
+	int           rv;
+	struct addarg aa;
+
+	TEST_CHECK(nng_mtx_alloc(&aa.mx) == 0);
+	TEST_CHECK(nng_cv_alloc(&aa.cv, aa.mx) == 0);
+	aa.cnt = 0;
+
+	TEST_CHECK((rv = nng_thread_create(&thr, add, &aa)) == 0);
+
+	nng_mtx_lock(aa.mx);
+	while (aa.cnt == 0) {
+		nng_cv_wait(aa.cv);
+	}
+	nng_mtx_unlock(aa.mx);
+	nng_thread_destroy(thr);
+	TEST_CHECK(aa.cnt == 1);
+
+	nng_cv_free(aa.cv);
+	nng_mtx_free(aa.mx);
+}
+
+void
+test_random(void)
+{
+	int      same = 0;
+	uint32_t values[1000];
+
+	for (int i = 0; i < 1000; i++) {
+		values[i] = nng_random();
+	}
+	for (int i = 0; i < 1000; i++) {
+		for (int j = 0; j < i; j++) {
+			if (values[j] == values[i]) {
+				same++;
+			}
+		}
+	}
+
+	// 1% reproduction is *highly* unlikely.
+	// There are 4 billion possible options, we are only looking at
+	// 1000 of them.  In general, it would be an extreme outlier
+	// to see more than 2 repeats, unless you RNG is biased.
+	TEST_CHECK_(same < 5, "fewer than 5 in 1000 repeats: %d", same);
 }
 
 TEST_LIST = {
 	{ "sleep", test_sleep },
 	{ "clock", test_clock },
 	{ "mutex", test_mutex },
-        { "thread", test_thread },
-        { "condvar", test_condvar },
+	{ "thread", test_thread },
+	{ "condvar", test_condvar },
+	{ "random", test_random },
 	{ NULL, NULL },
 };