From 8d7680408fc3b667166c30c1503e2c03242ca825 Mon Sep 17 00:00:00 2001
From: Logan007 <you@example.com>
Date: Sun, 30 Aug 2020 03:05:48 +0545
Subject: [PATCH] cosmetics on random numbers code

---
 include/n2n.h            |  8 +-------
 include/random_numbers.h | 44 +++++++++++++++++++++++++++++++++-------
 src/random_numbers.c     | 20 ++++++++----------
 3 files changed, 47 insertions(+), 25 deletions(-)

diff --git a/include/n2n.h b/include/n2n.h
index dc08248..da5c0c3 100644
--- a/include/n2n.h
+++ b/include/n2n.h
@@ -83,14 +83,12 @@
 #define N2N_CAN_NAME_IFACE 1
 #include <linux/netlink.h>
 #include <linux/rtnetlink.h>
-#include <sys/syscall.h>
 #include <unistd.h>
 #include <net/if_arp.h>
 #include <net/if.h>
 #include <linux/if_tun.h>
 #include <linux/netlink.h>
 #include <linux/rtnetlink.h>
-#define GRND_NONBLOCK       1
 #endif /* #ifdef __linux__ */
 
 #ifdef __FreeBSD__
@@ -100,10 +98,6 @@
 #include <syslog.h>
 #include <sys/wait.h>
 
-#if defined (__RDRND__) || defined (__RDSEED__)
-#include <immintrin.h>
-#endif
-
 #define ETH_ADDR_LEN 6
 
 struct ether_hdr
@@ -130,12 +124,12 @@ typedef struct ether_hdr ether_hdr_t;
 #include <assert.h>
 #include <sys/stat.h>
 #include <stdint.h>
+
 #ifdef N2N_HAVE_AES
 #include <openssl/opensslv.h>
 #include <openssl/crypto.h>
 #endif
 
-
 #define closesocket(a) close(a)
 #endif /* #ifndef WIN32 */
 
diff --git a/include/random_numbers.h b/include/random_numbers.h
index 6271163..77a7ba2 100644
--- a/include/random_numbers.h
+++ b/include/random_numbers.h
@@ -16,19 +16,46 @@
  *
  */
 
-/* The WIN32 code is still untested and thus commented
+
+#ifndef RND_H
+#define RND_H
+
+
+#include <stdint.h>
+#include <stddef.h>
+#include <time.h>        // time, clock
+
+#include "n2n.h"         // traceEvent
+
+// syscall and inquiring random number from hardware generators might fail, so we will retry
+#define RND_RETRIES      1000
+
+#if defined (__linux__)
+#include <sys/syscall.h> // syscall
+#ifdef SYS_getrandom
+#define GRND_NONBLOCK       1
+#include <errno.h>       // errno
+#endif
+#endif
+
+#if defined (__RDRND__) || defined (__RDSEED__)
+#include <immintrin.h>  // _rdrand64_step, rdseed4_step
+#endif
+
+/* The WIN32 code is still untested and thus commented, also see random_numbers.c
    #if defined (WIN32)
-   #include <Wincrypt.h>
-   #endif 
+   #include <Wincrypt.h>   // HCTYPTPROV, Crypt*-functions
+   #endif
 */
 
-struct rn_generator_state_t {
+
+typedef struct rn_generator_state_t {
   uint64_t a, b;
-};
+} rn_generator_state_t;
 
-struct splitmix64_state_t {
+typedef struct splitmix64_state_t {
     uint64_t s;
-};
+} splitmix64_state_t;
 
 
 int n2n_srand (uint64_t seed);
@@ -36,3 +63,6 @@ int n2n_srand (uint64_t seed);
 uint64_t n2n_rand ();
 
 uint64_t n2n_seed ();
+
+
+#endif // RND_H
diff --git a/src/random_numbers.c b/src/random_numbers.c
index aa98fb8..1704796 100644
--- a/src/random_numbers.c
+++ b/src/random_numbers.c
@@ -16,11 +16,8 @@
  *
  */
 
-#ifdef SYS_getrandom
-#include <errno.h>
-#endif
 
-#include "n2n.h"
+#include "random_numbers.h"
 
 
 /* The following code offers an alterate pseudo random number generator
@@ -31,13 +28,13 @@
 
 /* The state must be seeded in a way that it is not all zero, choose some
    arbitrary defaults (in this case: taken from splitmix64) */
-static struct rn_generator_state_t rn_current_state = {
+static rn_generator_state_t rn_current_state = {
   .a    = 0x9E3779B97F4A7C15,
   .b    = 0xBF58476D1CE4E5B9 };
 
 
 /* used for mixing the initializing seed */
-static uint64_t splitmix64 (struct splitmix64_state_t *state) {
+static uint64_t splitmix64 (splitmix64_state_t *state) {
 
   uint64_t result = state->s;
 
@@ -51,8 +48,9 @@ static uint64_t splitmix64 (struct splitmix64_state_t *state) {
 
 
 int n2n_srand (uint64_t seed) {
+
   uint8_t i;
-  struct splitmix64_state_t smstate = {seed};
+  splitmix64_state_t smstate = {seed};
 
   rn_current_state.a = 0;
   rn_current_state.b = 0;
@@ -67,7 +65,7 @@ int n2n_srand (uint64_t seed) {
     rn_current_state.b = 0xBF58476D1CE4E5B9;
   }
 
-  /* stabilize in unlikely case of weak state with only a few bits set */
+  // stabilize in unlikely case of weak state with only a few bits set
   for(i = 0; i < 32; i++)
     n2n_rand();
 
@@ -160,16 +158,16 @@ uint64_t n2n_seed (void) {
      #ifdef WIN32
      HCRYPTPROV crypto_provider;
      CryptAcquireContext (&crypto_provider, NULL, (LPCWSTR)L"Microsoft Base Cryptographic Provider v1.0",
-     PROV_RSA_FULL, CRYPT_VERIFYCONTEXT);
+                          PROV_RSA_FULL, CRYPT_VERIFYCONTEXT);
      CryptGenRandom (crypto_provider, 8, &seed);
      CryptReleaseContext (crypto_provider, 0);
      ret += seed;
      #endif */
 
-  seed = time(NULL); /* UTC in seconds */
+  seed = time(NULL);             // UTC in seconds
   ret += seed;
 
-  seed = clock() * 18444244737;  /* clock() = ticks since program start */
+  seed = clock() * 18444244737;  // clock() = ticks since program start
   ret += seed;
 
   return ret;