wipeable_string: add hex_to_pod function

contrib/epee/include/hex.h

@@ -44,6 +44,7 @@ namespace epee
     static std::string string(const span<const std::uint8_t> src);
     //! \return A epee::wipeable_string containing hex of `src`.
     static epee::wipeable_string wipeable_string(const span<const std::uint8_t> src);
+    template<typename T> static epee::wipeable_string wipeable_string(const T &pod) { return wipeable_string(span<const uint8_t>((const uint8_t*)&pod, sizeof(pod))); }
 
     //! \return An array containing hex of `src`.
     template<std::size_t N>

contrib/epee/include/wipeable_string.h

@@ -28,10 +28,11 @@
 
 #pragma once
 
-#include <boost/optional/optional_fwd.hpp>
+#include <boost/optional/optional.hpp>
 #include <stddef.h>
 #include <vector>
 #include <string>
+#include "memwipe.h"
 #include "fnv1.h"
 
 namespace epee
@@ -65,6 +66,8 @@ namespace epee
     void trim();
     void split(std::vector<wipeable_string> &fields) const;
     boost::optional<wipeable_string> parse_hexstr() const;
+    template<typename T> inline bool hex_to_pod(T &pod) const;
+    template<typename T> inline bool hex_to_pod(tools::scrubbed<T> &pod) const { return hex_to_pod(unwrap(pod)); }
     void resize(size_t sz);
     void reserve(size_t sz);
     void clear();
@@ -79,6 +82,20 @@ namespace epee
   private:
     std::vector<char> buffer;
   };
+
+  template<typename T> inline bool wipeable_string::hex_to_pod(T &pod) const
+  {
+    static_assert(std::is_pod<T>::value, "expected pod type");
+    if (size() != sizeof(T) * 2)
+      return false;
+    boost::optional<epee::wipeable_string> blob = parse_hexstr();
+    if (!blob)
+      return false;
+    if (blob->size() != sizeof(T))
+      return false;
+    pod = *(const T*)blob->data();
+    return true;
+  }
 }
 
 namespace std

contrib/epee/src/wipeable_string.cpp

@@ -32,6 +32,8 @@
 #include "misc_log_ex.h"
 #include "wipeable_string.h"
 
+static constexpr const char hex[] = u8"0123456789abcdef";
+
 namespace
 {
   int atolower(int c)
@@ -197,7 +199,6 @@ boost::optional<epee::wipeable_string> wipeable_string::parse_hexstr() const
   const size_t len = size();
   const char *d = data();
   res->grow(0, len / 2);
-  static constexpr const char hex[] = u8"0123456789abcdef";
   for (size_t i = 0; i < len; i += 2)
   {
     char c = atolower(d[i]);

tests/unit_tests/wipeable_string.cpp

@@ -32,6 +32,7 @@
 
 #include "misc_log_ex.h"
 #include "wipeable_string.h"
+#include "hex.h"
 
 TEST(wipeable_string, ctor)
 {
@@ -202,3 +203,9 @@ TEST(wipeable_string, parse_hexstr)
   ASSERT_TRUE((s = epee::wipeable_string("414243").parse_hexstr()));
   ASSERT_EQ(*s, epee::wipeable_string("ABC"));
 }
+
+TEST(wipeable_string, to_hex)
+{
+  ASSERT_TRUE(epee::to_hex::wipeable_string(epee::span<const uint8_t>((const uint8_t*)"", 0)) == epee::wipeable_string(""));
+  ASSERT_TRUE(epee::to_hex::wipeable_string(epee::span<const uint8_t>((const uint8_t*)"abc", 3)) == epee::wipeable_string("616263"));
+}