WebSocket ping, fixes, coverage:

* Improve test coverage
* tests for invokable in composed ops

* Update documentation
* Add License badge to README
* Target Windows 7 SDK and later
* Make role_type private
* Remove extra unused masking functions
* Allow stream reuse / reconnect after failure
* Restructure logic of composed operations
* Allow 0 for read_message_max meaning no limit
* Respect keep alive when building HTTP responses
* Check version in upgrade request
* Response with 426 status on unsupported WebSocket version
* Remove unnecessary Sec-WebSocket-Key in HTTP responses
* Rename to mask_buffer_size

* Remove maybe_throw
* Add ping, async_ping, async_on_pong
* Add ping_op
* Add pong_op
* Fix crash in accept_op
* Fix suspend in close_op
* Fix read_frame_op logic
* Fix crash in read_op
* Fix races in echo sync and async echo servers

test/core/CMakeLists.txt

@@ -29,6 +29,7 @@ add_executable (core-tests
     write_streambuf.cpp
     detail/base64.cpp
     detail/empty_base_optimization.cpp
+    detail/get_lowest_layer.cpp
     detail/sha1.cpp
 )
 

test/core/detail/get_lowest_layer.cpp

@@ -0,0 +1,88 @@
+//
+// Copyright (c) 2013-2016 Vinnie Falco (vinnie dot falco at gmail dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+// Test that header file is self-contained.
+#include <beast/core/detail/get_lowest_layer.hpp>
+
+#include <beast/unit_test/suite.hpp>
+#include <type_traits>
+
+namespace beast {
+namespace detail {
+
+class get_lowest_layer_test
+    : public beast::unit_test::suite
+{
+public:
+    struct F1
+    {
+    };
+
+    struct F2
+    {
+    };
+
+    template<class F>
+    struct F3
+    {
+        using next_layer_type =
+            typename std::remove_reference<F>::type;
+
+        using lowest_layer_type = typename
+            get_lowest_layer<next_layer_type>::type;
+    };
+
+    template<class F>
+    struct F4
+    {
+        using next_layer_type =
+            typename std::remove_reference<F>::type;
+
+        using lowest_layer_type = typename
+            get_lowest_layer<next_layer_type>::type;
+    };
+
+    void
+    run()
+    {
+        static_assert(! has_lowest_layer<F1>::value, "");
+        static_assert(! has_lowest_layer<F2>::value, "");
+        static_assert(has_lowest_layer<F3<F1>>::value, "");
+        static_assert(has_lowest_layer<F4<F3<F2>>>::value, "");
+
+        static_assert(std::is_same<
+            get_lowest_layer<F1>::type, F1>::value, "");
+
+        static_assert(std::is_same<
+            get_lowest_layer<F2>::type, F2>::value, "");
+
+        static_assert(std::is_same<
+            get_lowest_layer<F3<F1>>::type, F1>::value, "");
+
+        static_assert(std::is_same<
+            get_lowest_layer<F3<F2>>::type, F2>::value, "");
+
+        static_assert(std::is_same<
+            get_lowest_layer<F4<F1>>::type, F1>::value, "");
+
+        static_assert(std::is_same<
+            get_lowest_layer<F4<F2>>::type, F2>::value, "");
+
+        static_assert(std::is_same<
+            get_lowest_layer<F4<F3<F1>>>::type, F1>::value, "");
+
+        static_assert(std::is_same<
+            get_lowest_layer<F4<F3<F2>>>::type, F2>::value, "");
+
+        pass();
+    }
+};
+
+BEAST_DEFINE_TESTSUITE(get_lowest_layer,core,beast);
+
+} // detail
+} // beast

test/core/prepare_buffers.cpp

@@ -89,6 +89,7 @@ public:
 
     void testIterator()
     {
+        using boost::asio::buffer_size;
         using boost::asio::const_buffer;
         char b[3];
         std::array<const_buffer, 3> bs{{
@@ -98,7 +99,12 @@ public:
         auto pb = prepare_buffers(2, bs);
         std::size_t n = 0;
         for(auto it = pb.end(); it != pb.begin(); --it)
+        {
+            decltype(pb)::const_iterator it2(std::move(it));
+            expect(buffer_size(*it2) == 1);
+            it = std::move(it2);
             ++n;
+        }
         expect(n == 2);
     }