utils/src/RandomString.cpp

   1 #include <random>
   2 #include <time.h>
   3 #include <unistd.h>
   4 #include <stdlib.h>
   5 #include <atomic>
   6 #include "BitTwiddle.hpp"
   7 #include "RandomString.h"
   8
   9 static std::atomic<uint32_t> s_rnd_next_seed;
  10
  11 size_t RandomStringBuffer(unsigned char *out, size_t min_len, size_t max_len, unsigned int flags)
  12 {
  13         std::mt19937 rng;
  14         rng.seed(getpid() ^ time(NULL) ^ RevBytes(uint32_t(clock())) ^ uint32_t(s_rnd_next_seed));
  15         size_t len = min_len;
  16         if (max_len > min_len) {
  17                 std::uniform_int_distribution<std::mt19937::result_type> len_dist(0, max_len - min_len);
  18                 len+= len_dist(rng);
  19         }
  20
  21         std::uniform_int_distribution<std::mt19937::result_type> chr_dist(0, 0xff);
  22         for (size_t i = 0; i < len; ) {
  23                 unsigned char v = chr_dist(rng);
  24                 if (v == 0) {
  25                         if ((flags & RNDF_ZERO) == 0) {
  26                                 continue;
  27                         }
  28                 } else if (v >= 'A' && v <= 'Z') {
  29                         if ((flags & RNDF_HICASE) == 0) {
  30                                 continue;
  31                         }
  32                 } else if (v >= 'a' && v <= 'z') {
  33                         if ((flags & RNDF_LOCASE) == 0) {
  34                                 continue;
  35                         }
  36                 } else if (v >= '0' && v <= '9') {
  37                         if ((flags & RNDF_DIGITS) == 0) {
  38                                 continue;
  39                         }
  40                 } else if (v >= 128) {
  41                         if ((flags & RNDF_X128) == 0) {
  42                                 continue;
  43                         }
  44                 } else if ((flags & RNDF_ETC) == 0) {
  45                         continue;
  46                 }
  47
  48                 out[i] = v;
  49                 ++i;
  50         }
  51
  52         std::uniform_int_distribution<std::mt19937::result_type> seed_dist(0, 0xffffffff);
  53         s_rnd_next_seed = seed_dist(rng);
  54
  55         return len;
  56 }
  57
  58 void RandomStringAppend(std::string &out, size_t min_len, size_t max_len, unsigned int flags)
  59 {
  60         const size_t orig_size = out.size();
  61         out.resize(orig_size + max_len);
  62         size_t len = RandomStringBuffer(&out[orig_size], min_len, max_len, flags);
  63         out.resize(orig_size + len);
  64 }