RPS

rps/game-redacted.c

@@ -0,0 +1,154 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <string.h>
+#include <time.h>
+#include <unistd.h>
+#include <sys/time.h>
+#include <sys/types.h>
+
+
+#define WAIT 60
+
+
+
+static const char* flag = "[REDACTED]";
+
+char* hands[3] = {"rock", "paper", "scissors"};
+char* loses[3] = {"paper", "scissors", "rock"};
+int wins = 0;
+
+
+
+int tgetinput(char *input, unsigned int l)
+{
+    fd_set          input_set;
+    struct timeval  timeout;
+    int             ready_for_reading = 0;
+    int             read_bytes = 0;
+    
+    if( l <= 0 )
+    {
+      printf("'l' for tgetinput must be greater than 0\n");
+      return -2;
+    }
+    
+    
+    /* Empty the FD Set */
+    FD_ZERO(&input_set );
+    /* Listen to the input descriptor */
+    FD_SET(STDIN_FILENO, &input_set);
+
+    /* Waiting for some seconds */
+    timeout.tv_sec = WAIT;    // WAIT seconds
+    timeout.tv_usec = 0;    // 0 milliseconds
+
+    /* Listening for input stream for any activity */
+    ready_for_reading = select(1, &input_set, NULL, NULL, &timeout);
+    /* Here, first parameter is number of FDs in the set, 
+     * second is our FD set for reading,
+     * third is the FD set in which any write activity needs to updated,
+     * which is not required in this case. 
+     * Fourth is timeout
+     */
+
+    if (ready_for_reading == -1) {
+        /* Some error has occured in input */
+        printf("Unable to read your input\n");
+        return -1;
+    } 
+
+    if (ready_for_reading) {
+        read_bytes = read(0, input, l-1);
+        if(input[read_bytes-1]=='\n'){
+        --read_bytes;
+        input[read_bytes]='\0';
+        }
+        if(read_bytes==0){
+            printf("No data given.\n");
+            return -4;
+        } else {
+            return 0;
+        }
+    } else {
+        printf("Timed out waiting for user input. Press Ctrl-C to disconnect\n");
+        return -3;
+    }
+
+    return 0;
+}
+
+
+bool play () {
+  char player_turn[100];
+  srand(time(0));
+  int r;
+
+  printf("Please make your selection (rock/paper/scissors):\n");
+  r = tgetinput(player_turn, 100);
+  // Timeout on user input
+  if(r == -3)
+  {
+    printf("Goodbye!\n");
+    exit(0);
+  }
+
+  int computer_turn = rand() % 3;
+  printf("You played: %s\n", player_turn);
+  printf("The computer played: %s\n", hands[computer_turn]);
+
+  if (strstr(player_turn, loses[computer_turn])) {
+    puts("You win! Play again?");
+    return true;
+  } else {
+    puts("Seems like you didn't win this time. Play again?");
+    return false;
+  }
+}
+
+
+int main () {
+  char input[3] = {'\0'};
+  int command;
+  int r;
+
+  puts("Welcome challenger to the game of Rock, Paper, Scissors");
+  puts("For anyone that beats me 5 times in a row, I will offer up a flag I found");
+  puts("Are you ready?");
+  
+  while (true) {
+    puts("Type '1' to play a game");
+    puts("Type '2' to exit the program");
+    r = tgetinput(input, 3);
+    // Timeout on user input
+    if(r == -3)
+    {
+      printf("Goodbye!\n");
+      exit(0);
+    }
+    
+    if ((command = strtol(input, NULL, 10)) == 0) {
+      puts("Please put in a valid number");
+      
+    } else if (command == 1) {
+      printf("\n\n");
+      if (play()) {
+        wins++;
+      } else {
+        wins = 0;
+      }
+
+      if (wins >= 5) {
+        puts("Congrats, here's the flag!");
+        puts(flag);
+      }
+    } else if (command == 2) {
+      return 0;
+    } else {
+      puts("Please type either 1 or 2");
+    }
+  }
+
+  return 0;
+}
+

rps/sol.py

@@ -0,0 +1,32 @@
+#!/usr/bin/env python
+from pwn import *
+
+wins = 0
+rounds = 0
+
+def play_round(wins):
+    conn.recvuntil(b"exit the program")
+    conn.recvline()
+    conn.sendline(b"1")
+    conn.recvuntil(b"s):")
+    conn.recvline()
+    conn.sendline(b"rock")
+    conn.recvuntil(b"computer played")
+    conn.recvline()
+    result = conn.recvline()
+    if b"You win" in result:
+        return wins+1
+    else:
+        return 0
+
+conn = remote("saturn.picoctf.net", 49891)
+
+p = log.progress("brute-forcing solution")
+while wins < 5:
+    rounds += 1
+    wins = play_round(wins)
+    p.status(f"round {rounds}, wins: {wins}")
+p.success("won 5 rounds")
+
+conn.interactive()
+