Switch custom RNG for libsodium

CMakeLists.txt

@@ -485,6 +485,7 @@ if(NINTENDO_SWITCH)
     Source/platform/switch/network.cpp
     Source/platform/switch/keyboard.cpp
     Source/platform/switch/docking.cpp
+    Source/platform/switch/random.cpp
     Source/platform/switch/asio/net/if.c
     Source/platform/switch/asio/sys/signal.c)
 endif()

Source/main.cpp

@@ -1,6 +1,7 @@
 #include <SDL.h>
 #ifdef __SWITCH__
 #include "platform/switch/network.h"
+#include "platform/switch/random.hpp"
 #endif
 #ifdef __3DS__
 #include "platform/ctr/system.h"
@@ -26,6 +27,7 @@ int main(int argc, char **argv)
 {
 #ifdef __SWITCH__
 	switch_enable_network();
+	randombytes_switchrandom_init();
 #endif
 #ifdef __3DS__
 	ctr_sys_init();

Source/platform/switch/random.cpp

@@ -0,0 +1,54 @@
+#include <sys/types.h>
+#include <sodium.h>
+
+extern "C" {
+#include <switch/sf/service.h>
+#include <switch/services/csrng.h>
+}
+
+static const char *randombytes_switchrandom_implementation_name()
+{
+	return "switchrandom";
+}
+
+static bool randombytes_switchrandom_tryfill(void *const buf, const size_t size)
+{
+	Result res;
+	Service *csrngService = csrngGetServiceSession();
+	if (!serviceIsActive(csrngService)) {
+		res = csrngInitialize();
+		if (!R_SUCCEEDED(res))
+			return false;
+	}
+	res = csrngGetRandomBytes(buf, size);
+	return R_SUCCEEDED(res);
+}
+
+static uint32_t randombytes_switchrandom()
+{
+	uint32_t num;
+	if (!randombytes_switchrandom_tryfill(&num, sizeof(uint32_t)))
+		sodium_misuse();
+	return num;
+}
+
+static void randombytes_switchrandom_buf(void *const buf, const size_t size)
+{
+	if (!randombytes_switchrandom_tryfill(buf, size))
+		sodium_misuse();
+}
+
+struct randombytes_implementation randombytes_switchrandom_implementation = {
+	randombytes_switchrandom_implementation_name,
+	randombytes_switchrandom,
+	nullptr,
+	nullptr,
+	randombytes_switchrandom_buf,
+	nullptr
+};
+
+void randombytes_switchrandom_init()
+{
+	randombytes_set_implementation(&randombytes_switchrandom_implementation);
+	atexit(csrngExit);
+}

Source/platform/switch/random.hpp

@@ -0,0 +1,2 @@
+#pragma once
+void randombytes_switchrandom_init();