stuff

training/IntroZ3/tasks/chall2_dreamer/dream.c

@@ -0,0 +1,59 @@
+#include <stdlib.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <sys/mman.h>
+#include <string.h>
+#define ROTL(X, N)  (((X) << (N)) | ((X) >> (8 * sizeof(X) - (N))))
+#define ROTR(X, N)  (((X) >> (N)) | ((X) << (8 * sizeof(X) - (N))))
+unsigned long STATE; 
+unsigned long CURRENT;
+
+char custom_random(){
+    STATE = ROTL(STATE,30) ^ ROTR(STATE,12) ^ ROTL(STATE,42) ^ ROTL(STATE,4) ^ ROTR(STATE,5);
+    return STATE % 256;
+}
+
+void* experience(long origin){
+  char* ccol= mmap (0,1024, PROT_READ|PROT_WRITE|PROT_EXEC,
+              MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
+    size_t k = 0;
+    while(k<106){
+        *(ccol+k) = 0x90; //nop just in case;
+        k++;
+    }
+    k=16;
+    *((int*)ccol) = origin;
+    while(k<100){
+        *(ccol+k)=custom_random();
+        k++;
+    }
+    return ccol;
+
+}
+
+void sleepy(void * dream){
+    int (*d)(void) = (void*)dream;
+    d();
+}
+
+
+void win(){
+    execv("/bin/sh",NULL);
+}
+
+void setup(){
+    setvbuf(stdin, NULL, _IONBF, 0);
+    setvbuf(stdout, NULL, _IONBF, 0);
+    setvbuf(stderr, NULL, _IONBF, 0);
+}
+
+int main(){
+    setup();
+    long seed=0;
+    printf("the win is yours at %p\n", win);
+    scanf("%ld",&seed); 
+    STATE = seed;
+    printf("what are you thinking about?");
+    scanf("%ld",&seed);
+    sleepy(experience(seed));
+}