makepass.c

建立一个模拟数据库来存储你的登录用户名、密码

/* makepass.c - Make a UNIX password */
/* compile with: gcc -o makepass makepass.c -lcrypt */
/* usage: "makepass 'salt'" */

#include <crypt.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <strings.h>
#include  <unistd.h>

int is_salt(char *salt)
{
  char salts[] =
    "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789./";

  return strlen(salt) == 2 &&
    strchr(salts, salt[0]) != 0 &&  strchr(salts, salt[1]) != 0 &&
    salt[0] != '\0' &&  salt[1] != '\0';
}

int main(int argc, char *argv[])
{
  char *clear;
  char clear1[9];
  char *clear2;

  if(argc != 2) {
    fprintf(stderr, "Usage: %s salt\n", argv[0]);
    return 1;
  }
  
  if(!is_salt(argv[1])) {
    fprintf(stderr, "(%s) is illegal salt!\n", argv[1]);
    return 2;
  }
  
  clear = getpass("Password: ");
  if(clear == NULL) {
    bzero(clear, 8);
    fprintf(stderr, "Not a tty!");
    return 3;
  }
  
  strncpy(clear1, clear, 8);
  bzero(clear, 8);

  clear2 = getpass("Re-enter password: ");
  if(clear2 == NULL) {
    bzero(clear2, 8);
    fprintf(stderr, "Not a tty!");
    return 3;
  }

  if(strcmp(clear1, clear2) != 0) {
    fprintf(stderr, "Sorry, passwords don't match.\n");
    bzero(clear1, 8);
    bzero(clear2, 8);
    return 4;
  }

  printf("Encrypted password: \"%s\"\n", crypt(clear1, argv[1]));
  bzero(clear1, 8);
  bzero(clear2, 8);

  return 0;
}