wallet: wipe seed from memory where appropriate

contrib/epee/src/hex.cpp

@@ -52,17 +52,21 @@ namespace epee
     }
   }
 
-  std::string to_hex::string(const span<const std::uint8_t> src)
+  template<typename T>
+  T to_hex::convert(const span<const std::uint8_t> src)
   {
     if (std::numeric_limits<std::size_t>::max() / 2 < src.size())
       throw std::range_error("hex_view::to_string exceeded maximum size");
 
-    std::string out{};
+    T out{};
     out.resize(src.size() * 2);
-    buffer_unchecked(std::addressof(out[0]), src);
+    to_hex::buffer_unchecked((char*)out.data(), src); // can't see the non const version in wipeable_string??
     return out;
   }
 
+  std::string to_hex::string(const span<const std::uint8_t> src) { return convert<std::string>(src); }
+  epee::wipeable_string to_hex::wipeable_string(const span<const std::uint8_t> src) { return convert<epee::wipeable_string>(src); }
+
   void to_hex::buffer(std::ostream& out, const span<const std::uint8_t> src)
   {
     write_hex(std::ostreambuf_iterator<char>{out}, src);

contrib/epee/src/wipeable_string.cpp

@@ -26,11 +26,22 @@
 // STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
 // THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
+#include <boost/optional/optional.hpp>
 #include <string.h>
 #include "memwipe.h"
 #include "misc_log_ex.h"
 #include "wipeable_string.h"
 
+namespace
+{
+  int atolower(int c)
+  {
+    if (c >= 'A' && c <= 'Z')
+      c |= 32;
+    return c;
+  }
+}
+
 namespace epee
 {
 
@@ -69,6 +80,12 @@ wipeable_string::wipeable_string(const char *s)
   memcpy(buffer.data(), s, size());
 }
 
+wipeable_string::wipeable_string(const char *s, size_t len)
+{
+  grow(len);
+  memcpy(buffer.data(), s, len);
+}
+
 wipeable_string::~wipeable_string()
 {
   wipe();
@@ -109,9 +126,100 @@ void wipeable_string::push_back(char c)
   buffer.back() = c;
 }
 
-void wipeable_string::pop_back()
+void wipeable_string::operator+=(char c)
 {
-  resize(size() - 1);
+  push_back(c);
+}
+
+void wipeable_string::append(const char *ptr, size_t len)
+{
+  const size_t orgsz = size();
+  CHECK_AND_ASSERT_THROW_MES(orgsz < std::numeric_limits<size_t>::max() - len, "Appended data too large");
+  grow(orgsz + len);
+  if (len > 0)
+    memcpy(data() + orgsz, ptr, len);
+}
+
+void wipeable_string::operator+=(const char *s)
+{
+  append(s, strlen(s));
+}
+
+void wipeable_string::operator+=(const epee::wipeable_string &s)
+{
+  append(s.data(), s.size());
+}
+
+void wipeable_string::operator+=(const std::string &s)
+{
+  append(s.c_str(), s.size());
+}
+
+void wipeable_string::trim()
+{
+  size_t prefix = 0;
+  while (prefix < size() && data()[prefix] == ' ')
+    ++prefix;
+  if (prefix > 0)
+    memmove(buffer.data(), buffer.data() + prefix, size() - prefix);
+
+  size_t suffix = 0;
+  while (suffix < size()-prefix && data()[size() - 1 - prefix - suffix] == ' ')
+    ++suffix;
+
+  resize(size() - prefix - suffix);
+}
+
+void wipeable_string::split(std::vector<wipeable_string> &fields) const
+{
+  fields.clear();
+  size_t len = size();
+  const char *ptr = data();
+  bool space = true;
+  while (len--)
+  {
+    const char c = *ptr++;
+    if (c != ' ')
+    {
+      if (space)
+        fields.push_back({});
+      fields.back().push_back(c);
+    }
+    space = c == ' ';
+  }
+}
+
+boost::optional<epee::wipeable_string> wipeable_string::parse_hexstr() const
+{
+  if (size() % 2 != 0)
+    return boost::none;
+  boost::optional<epee::wipeable_string> res = epee::wipeable_string("");
+  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]);
+    const char *ptr0 = strchr(hex, c);
+    if (!ptr0)
+      return boost::none;
+    c = atolower(d[i+1]);
+    const char *ptr1 = strchr(hex, c);
+    if (!ptr1)
+      return boost::none;
+    res->push_back(((ptr0-hex)<<4) | (ptr1-hex));
+  }
+  return res;
+}
+
+char wipeable_string::pop_back()
+{
+  const size_t sz = size();
+  CHECK_AND_ASSERT_THROW_MES(sz > 0, "Popping from an empty string");
+  const char c = buffer.back();
+  resize(sz - 1);
+  return c;
 }
 
 void wipeable_string::resize(size_t sz)