Merge pull request #15 from CodeAnarchist/random

implement global random(xoroshiro128+)

Author: Di Ferrari

kernel/kernel.c

@@ -17,6 +17,7 @@
 #include "networking/processes/net_proc.h"
 #include "memory/page_allocator.h"
 #include "networking/network.h"
+#include "math/random.h"
 
 void kernel_main() {
 
@@ -27,7 +28,11 @@ void kernel_main() {
     enable_uart();
     kprintf_l("UART output enabled");
     // enable_talloc_verbose();
-    
+    uint64_t seed;
+    asm volatile("mrs %0, cntvct_el0" : "=r"(seed)); //virtual timer counter as entropy source for rng seed
+    rng_init_global(seed);
+    kprintf("Random init. seed: %i\n", seed);
+    //kprintf("Next32: %i\n", rng_next32(&global_rng));
     set_exception_vectors();
     kprintf_l("Exception vectors set");
 
@@ -86,4 +91,4 @@ void kernel_main() {
 
     panic("Kernel did not activate any process");
 
-}
+}

shared/math/random.c

@@ -0,0 +1,84 @@
+#include "random.h"
+#include "std/memfunctions.h"
+
+rng_t global_rng;
+
+void rng_seed(rng_t* rng, uint64_t seed){ //i guess it is "private", no definition in header
+    uint64_t z = seed + 0x9E3779B97F4A7C15;
+    z = (z ^ (z >> 30)) * 0xBF58476D1CE4E5B9;
+    z = (z ^ (z >> 27)) *0x94D049BB133111EB;
+    rng->s0 = z ^ (z >> 31);
+
+    z = seed + 0x9E3779B97F4A7C15 + 1;
+    z = (z ^ (z >> 30)) *0xBF58476D1CE4E5B9;
+    z = (z ^ (z >> 27))*0x94D049BB133111EB;
+    rng->s1 = z ^ (z >> 31);
+}
+
+uint64_t rng_next64(rng_t* rng){
+    uint64_t s0 = rng->s0;
+    uint64_t s1 = rng->s1;
+    uint64_t result = s0 + s1;
+
+    s1 ^= s0;
+    rng->s0 = rotl(s0, 55)^s1^(s1 << 14);
+    rng->s1 = rotl(s1, 36);
+
+    return result;
+}
+
+uint32_t rng_next32(rng_t* rng){
+    return (uint32_t)(rng_next64(rng) >> 32);
+}
+
+uint16_t rng_next16(rng_t* rng){
+    return (uint16_t)(rng_next64(rng) >> 48);
+}
+
+uint8_t rng_next8(rng_t* rng){
+    return (uint8_t)(rng_next64(rng) >> 56);
+}
+
+uint64_t rng_between64(rng_t* rng, uint64_t min, uint64_t max){
+    if (max <= min) return min;
+    return rng_next64(rng) % (max - min) + min;
+}
+
+uint32_t rng_between32(rng_t* rng, uint32_t min, uint32_t max){
+    if (max <= min) return min;
+    return rng_next64(rng) % (max - min) + min;
+}
+
+uint16_t rng_between16(rng_t* rng, uint16_t min, uint16_t max){
+    if (max <= min) return min;
+    return (uint16_t)(rng_next64(rng) % (max - min)) + min;
+}
+
+uint8_t rng_between8(rng_t* rng, uint8_t min, uint8_t max){
+    if (max <= min) return min;
+    return (uint8_t)(rng_next64(rng) % (max - min)) + min;
+}
+
+void rng_fill64(rng_t* rng, uint64_t* dst, uint32_t count){
+    for (uint32_t i = 0; i < count; i++)
+        dst[i] = rng_next64(rng);
+}
+
+void rng_fill32(rng_t* rng, uint32_t* dst, uint32_t count){
+    for (uint32_t i = 0; i < count; i++)
+        dst[i] = rng_next32(rng);
+}
+
+void rng_fill16(rng_t* rng, uint16_t* dst, uint32_t count){
+    for (uint32_t i = 0; i < count; i++)
+        dst[i] = rng_next16(rng);
+}
+
+void rng_fill8(rng_t* rng, uint8_t* dst, uint32_t count){
+    for (uint32_t i = 0; i < count; i++)
+        dst[i] = rng_next8(rng);
+}
+
+void rng_init_global(uint64_t seed) {
+    rng_seed(&global_rng, seed);
+}

shared/math/random.h

@@ -0,0 +1,41 @@
+#pragma once
+
+#include "types.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+//xoroshiro128+, pseudorandom
+typedef struct{
+    uint64_t s0;
+    uint64_t s1;
+}rng_t;
+
+static inline uint64_t rotl(uint64_t x, int k){
+    return (x << k)|(x >> (64 - k));
+}
+extern rng_t global_rng; //use &global_rng as rng_t* rng argument
+//init
+void rng_init_global(uint64_t seed);
+//single random
+uint8_t  rng_next8(rng_t* rng);
+uint16_t rng_next16(rng_t* rng);
+uint32_t rng_next32(rng_t* rng);
+uint64_t rng_next64(rng_t* rng);
+
+//random in range
+uint8_t  rng_between8(rng_t* rng, uint8_t min, uint8_t max);
+uint16_t rng_between16(rng_t* rng, uint16_t min, uint16_t max);
+uint32_t rng_between32(rng_t* rng, uint32_t min, uint32_t max);
+uint64_t rng_between64(rng_t* rng, uint64_t min, uint64_t max);
+
+//array fill
+void rng_fill8(rng_t* rng, uint8_t* dst, uint32_t count);
+void rng_fill16(rng_t* rng, uint16_t* dst, uint32_t count);
+void rng_fill32(rng_t* rng, uint32_t* dst, uint32_t count);
+void rng_fill64(rng_t* rng, uint64_t* dst, uint32_t count);
+
+#ifdef __cplusplus
+}
+#endif
+

shared/net/dhcp.c

@@ -1,5 +1,6 @@
 #include "dhcp.h"
 #include "std/memfunctions.h"
+#include "math/random.h"
 
 void create_dhcp_packet(uintptr_t p, dhcp_request *payload){
     network_connection_ctx source = (network_connection_ctx){
@@ -15,7 +16,7 @@ void create_dhcp_packet(uintptr_t p, dhcp_request *payload){
         .htype = 1,//Ethernet
         .hlen = 6,//Mac length
         .hops = 0,
-        .xid = 372,//Transaction ID: Static, could be random
+        .xid = rng_next32(&global_rng),//Transaction ID: RANDOM
         .secs = 0,
         .flags = __builtin_bswap16(0x8000),//Broadcast
         .ciaddr = 0,
@@ -63,4 +64,6 @@ uint16_t dhcp_parse_option(dhcp_packet *pack, uint16_t option){
         if (pack->options[i] == option) return i;
 
     return 0;
-}
+}
+
+