// gcc ./cxxdition_rxxe.c -o pwn
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <unistd.h>

#define ROUNDS 1000000

int passwd[4];
int input[4];

void init() {
    setvbuf(stdin, 0LL, 2, 0LL);
    setvbuf(stdout, 0LL, 2, 0LL);
    setvbuf(stderr, 0LL, 2, 0LL);
}


void *init_passwd(void *arg) {
    init();
    srand(time(NULL));
    for(int i = 0; i < ROUNDS; ++i) {
        passwd[i%4] ^= rand();
    }
    int fd = open("/dev/urandom", O_RDONLY);
    int key[4] = {};
    for(int i = 0; i < ROUNDS; ++i) {
        int tmp;
        read(fd, (char *) &tmp, sizeof(tmp));
        key[i%4] ^= tmp;
    }
    for(int i = 0; i < 4; ++i) {
        passwd[i] ^= key[i];
    }
    close(fd);
    return NULL;
}


void win() {
    init();
    char buf[0x30];
    int fd = open("flag", O_RDONLY);
    if(fd < 0) {
        perror("Open flag error!");
    }
    read(fd, buf, sizeof(buf)); 
    puts(buf);
    close(fd);
}


void *check_passwd(void * arg) {
    init();
    if(!memcmp(input, passwd, sizeof(passwd))) {
        puts("Login success!");
        puts("This is your flag:");
        win();
    } else {
        puts("Login failed!");
    }
}

int main() {
    pthread_t init_passwd_tid;
    pthread_create(&init_passwd_tid, NULL, init_passwd, NULL);
    while(1) {
        // sleep(1);
        puts("Password: ");
        read(0, (char *) &input, sizeof(input));        
        pthread_t check_passwd_tid;
        pthread_create(&check_passwd_tid, NULL, check_passwd, NULL);
    }
    return 0;
}