std_utils - Templatize bin2hex() / hex2bin()

FIX: The random generators, they were totally broken. (exhausting the entropy pool)

src/std_utils.cc

@@ -342,64 +342,39 @@ namespace pEp {
             std::this_thread::sleep_for(timespan);
         }
 
+        int fastrand(int max)
+        {
+            static int g_seed = static_cast<int>(
+                std::chrono::system_clock::now().time_since_epoch().count());
+            g_seed = (214013 * g_seed + 2531011);
+            return ((g_seed >> 16) & 0x7FFF) % max + 1;
+        }
+
         unsigned char random_char(unsigned char min, unsigned char max)
         {
-            std::random_device rd;
-            std::mt19937 gen(rd());
-            std::uniform_int_distribution<short> dis(static_cast<short>(min), static_cast<short>(max));
-            return static_cast<unsigned char>(dis(gen));
+            static unsigned seed1 = std::chrono::system_clock::now().time_since_epoch().count();
+            static std::mt19937 gen{ seed1 };
+            static std::uniform_int_distribution<unsigned char> dis(min, max);
+            return dis(gen);
         }
 
         std::string random_string(unsigned char min, unsigned char max, int len)
         {
             std::stringstream ret;
             for (int i = 0; i < len; i++) {
-                ret << random_char(97, 122);
+                ret << random_char(min, max);
             }
             return ret.str();
         }
 
-        std::string bin2hex(const std::vector<unsigned char> &bin)
+        std::string random_string_fast(unsigned char min, unsigned char max, int len)
         {
-            std::string ret{};
-            std::stringstream ss{};
-            for (const auto &i : bin) {
-                ss << std::hex << std::setfill('0') << std::setw(2) << (int)i;
-            }
-            ret = ss.str();
-            return ret;
-        }
-
-        std::vector<unsigned char> hex2bin(const std::string &hex_str)
-        {
-            std::vector<unsigned char> ret{};
-            if ((hex_str.size() % 2) != 0) {
-                throw std::runtime_error("hex2bin: Invalid hex string: must be even length");
-            }
-            for (int i = 0; i < hex_str.size(); i += 2) {
-                std::ostringstream val_hex{};
-                val_hex << hex_str.at(i);
-                val_hex << hex_str.at(i + 1);
-
-                int val_int;
-                std::istringstream conv_ss{ val_hex.str() };
-                conv_ss >> std::hex >> val_int;
-                if (conv_ss.fail()) {
-                    throw std::runtime_error("hex2bin: invalid hex string" + hex_str);
-                }
-                ret.push_back((unsigned char)val_int);
+            int range = std::max(max - min, 1);
+            std::stringstream ret;
+            for (int i = 0; i < len; i++) {
+                ret << (fastrand(range) + min);
             }
-            return ret;
-
-            //             alternative way
-            //            std::string extract;
-            //            for (std::string::const_iterator pos = hex_str.begin(); pos < hex_str.end(); pos += 2) {
-            //                extract.assign(pos, pos + 2);
-            //                ret.push_back(std::stoi(extract, nullptr, 16));
-            //            }
-            //            return ret;
+            return ret.str();
         }
-
-
     } // namespace Utils
 } // namespace pEp

src/std_utils.hh

@@ -93,12 +93,16 @@ namespace pEp {
         void sleep_millis(int milis);
 
         // Random
+        int fastrand(int max);
         unsigned char random_char(unsigned char min, unsigned char max);
         std::string random_string(unsigned char min, unsigned char max, int len);
+        std::string random_string_fast(unsigned char min, unsigned char max, int len);
 
         // conversion
-        std::vector<unsigned char> hex2bin(const std::string &hex_str);
-        std::string bin2hex(const std::vector<unsigned char>& bin);
+        template<class T>
+        std::string bin2hex(const T &bin);
+        template<class T>
+        T hex2bin(const std::string &hex_str);
     } // namespace Utils
 } // namespace pEp
 

src/std_utils.hxx

@@ -48,6 +48,49 @@ namespace pEp {
             }
         }
 
+        template<class T>
+        std::string bin2hex(const T &bin)
+        {
+            std::string ret{};
+            std::stringstream ss{};
+            for (const auto &i : bin) {
+                ss << std::hex << std::setfill('0') << std::setw(2) << (int)i;
+            }
+            ret = ss.str();
+            return ret;
+        }
+
+        template<class T>
+        T hex2bin(const std::string &hex_str)
+        {
+            T ret{};
+            if ((hex_str.size() % 2) != 0) {
+                throw std::runtime_error("hex2bin: Invalid hex string: must be even length");
+            }
+            for (int i = 0; i < hex_str.size(); i += 2) {
+                std::ostringstream val_hex{};
+                val_hex << hex_str.at(i);
+                val_hex << hex_str.at(i + 1);
+
+                int val_int;
+                std::istringstream conv_ss{ val_hex.str() };
+                conv_ss >> std::hex >> val_int;
+                if (conv_ss.fail()) {
+                    throw std::runtime_error("hex2bin: invalid hex string" + hex_str);
+                }
+                ret.push_back(static_cast<typename T::value_type>(val_int));
+            }
+            return ret;
+
+            //             alternative way
+            //            std::string extract;
+            //            for (std::string::const_iterator pos = hex_str.begin(); pos < hex_str.end(); pos += 2) {
+            //                extract.assign(pos, pos + 2);
+            //                ret.push_back(std::stoi(extract, nullptr, 16));
+            //            }
+            //            return ret;
+        }
+
     } // namespace Utils
 } // namespace pEp
 #endif // LIBPEPADAPTER_STD_UTILS_HXX

test/test_rand.cc

@@ -0,0 +1,47 @@
+#include "../src/std_utils.hh"
+#include "pEp/pEpLog.hh"
+#include <pEp/pitytest11/PityTest.hh>
+#include <iostream>
+#include <chrono>
+
+using namespace pEp;
+
+int main()
+{
+    pEp::Adapter::pEpLog::set_enabled(true);
+
+    pEpLog("Random functions benchmark");
+    int nr_mb = 10;
+    int nr_bytes = 1024 * 1024 * nr_mb;
+    pEpLog("generating " + std::to_string(nr_mb) + "MB's of random");
+
+    {
+        pEpLog("Utils::random_char()");
+        auto time_start = std::chrono::steady_clock::now();
+        for (int i = 0; i < nr_bytes; i++) {
+            Utils::random_char(0, 255);
+        }
+        auto time_end = std::chrono::steady_clock::now();
+        double duration_ms = (double)std::chrono::duration_cast<std::chrono::microseconds>(
+                                 time_end - time_start)
+                                 .count() /
+                             1000;
+        pEpLog("Time [ms/mbyte]:" + std::to_string(duration_ms / double(nr_mb)));
+    }
+    std::cout << "" << std::endl;
+    {
+        pEpLog("Utils::Fastrand()");
+        auto time_start = std::chrono::steady_clock::now();
+        for (int i = 0; i < nr_bytes; i++) {
+            Utils::fastrand(255);
+        }
+        auto time_end = std::chrono::steady_clock::now();
+        double duration_ms = (double)std::chrono::duration_cast<std::chrono::microseconds>(
+                                 time_end - time_start)
+                                 .count() /
+                             1000;
+
+        pEpLog("Time [ms/mbyte]:" + std::to_string(duration_ms / double(nr_mb)));
+    }
+    return 0;
+}