Problem: no C++ style secure memory allocator available

Solution: Added secure_allocator_t based on libsodium's memory management functions when available

CMakeLists.txt

@@ -871,6 +871,7 @@ set(cxx-sources
   req.hpp
   router.hpp
   scatter.hpp
+  secure_allocator.hpp
   select.hpp
   server.hpp
   session_base.hpp

Makefile.am

@@ -179,6 +179,7 @@ src_libzmq_la_SOURCES = \
 	src/router.hpp \
 	src/scatter.cpp \
 	src/scatter.hpp \
+	src/secure_allocator.hpp \
 	src/select.cpp \
 	src/select.hpp \
 	src/server.cpp \

src/curve_mechanism_base.hpp

@@ -48,6 +48,8 @@
 #include "mechanism_base.hpp"
 #include "options.hpp"
 
+#include <memory>
+
 namespace zmq
 {
 class curve_mechanism_base_t : public virtual mechanism_base_t

src/secure_allocator.hpp

@@ -0,0 +1,103 @@
+/*
+    Copyright (c) 2007-2019 Contributors as noted in the AUTHORS file
+
+    This file is part of libzmq, the ZeroMQ core engine in C++.
+
+    libzmq is free software; you can redistribute it and/or modify it under
+    the terms of the GNU Lesser General Public License (LGPL) as published
+    by the Free Software Foundation; either version 3 of the License, or
+    (at your option) any later version.
+
+    As a special exception, the Contributors give you permission to link
+    this library with independent modules to produce an executable,
+    regardless of the license terms of these independent modules, and to
+    copy and distribute the resulting executable under terms of your choice,
+    provided that you also meet, for each linked independent module, the
+    terms and conditions of the license of that module. An independent
+    module is a module which is not derived from or based on this library.
+    If you modify this library, you must extend this exception to your
+    version of the library.
+
+    libzmq is distributed in the hope that it will be useful, but WITHOUT
+    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+    FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
+    License for more details.
+
+    You should have received a copy of the GNU Lesser General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef __ZMQ_SECURE_ALLOCATOR_HPP_INCLUDED__
+#define __ZMQ_SECURE_ALLOCATOR_HPP_INCLUDED__
+
+#include "platform.hpp"
+#include "macros.hpp"
+
+#ifdef ZMQ_HAVE_CURVE
+
+#if defined(ZMQ_USE_LIBSODIUM)
+#include "sodium.h"
+#endif
+
+#include <memory>
+
+namespace zmq
+{
+#if defined(ZMQ_USE_LIBSODIUM)
+template <class T> struct secure_allocator_t
+{
+    typedef T value_type;
+
+    secure_allocator_t () {}
+    template <class U>
+    secure_allocator_t (const secure_allocator_t<U> &) ZMQ_NOEXCEPT
+    {
+    }
+    T *allocate (std::size_t n) ZMQ_NOEXCEPT
+    {
+        T *res = static_cast<T *> (sodium_allocarray (sizeof (T), n));
+        alloc_assert (res);
+        return res;
+    }
+    void deallocate (T *p, std::size_t) ZMQ_NOEXCEPT { sodium_free (p); }
+
+    // the following is only required with C++98
+    // TODO maybe make this conditionally compiled
+    typedef T *pointer;
+    typedef const T *const_pointer;
+    typedef T &reference;
+    typedef const T &const_reference;
+    typedef std::size_t size_type;
+    typedef std::ptrdiff_t difference_type;
+    template <class U> struct rebind
+    {
+        typedef secure_allocator_t<U> other;
+    };
+
+    void construct (pointer p, const_reference val)
+    {
+        new ((void *) p) value_type (val);
+    }
+    void destroy (pointer p) { p->~value_type (); }
+    size_type max_size () const { return SIZE_MAX; }
+};
+template <class T, class U>
+bool operator== (const secure_allocator_t<T> &, const secure_allocator_t<U> &)
+{
+    return true;
+}
+template <class T, class U>
+bool operator!= (const secure_allocator_t<T> &, const secure_allocator_t<U> &)
+{
+    return false;
+}
+#else
+template <typename T> struct secure_allocator_t : std::allocator<T>
+{
+};
+#endif
+}
+
+#endif
+
+#endif