Add the missing ssl::context callback in websocket_client_config (#1049)

* Add the missing ssl::context callback in websocket_client_config, borrowing heavily from http_client

* Add dependency on Boost and OpenSSL when websocketpp is used for Secure WebSocket, just like for http_client when CPPREST_HTTP_CLIENT_IMPL STREQUAL "asio"

Author: garethsb

Release/include/cpprest/ws_client.h

@@ -28,6 +28,17 @@
 #include <memory>
 #include <mutex>
 
+#if !defined(_WIN32) || !defined(__cplusplus_winrt)
+#if defined(__clang__)
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wconversion"
+#endif
+#include "boost/asio/ssl.hpp"
+#if defined(__clang__)
+#pragma clang diagnostic pop
+#endif
+#endif
+
 namespace web
 {
 // For backwards compatibility for when in the experimental namespace.
@@ -168,13 +179,36 @@ class websocket_client_config
     /// caution.</remarks>
     void set_validate_certificates(bool validate_certs) { m_validate_certificates = validate_certs; }
 
+#if !defined(_WIN32) || !defined(__cplusplus_winrt)
+    /// <summary>
+    /// Sets a callback to enable custom setting of the ssl context, at construction time.
+    /// </summary>
+    /// <param name="callback">A user callback allowing for customization of the ssl context at construction
+    /// time.</param>
+    void set_ssl_context_callback(const std::function<void(boost::asio::ssl::context&)>& callback)
+    {
+        m_ssl_context_callback = callback;
+    }
+
+    /// <summary>
+    /// Gets the user's callback to allow for customization of the ssl context.
+    /// </summary>
+    const std::function<void(boost::asio::ssl::context&)>& get_ssl_context_callback() const
+    {
+        return m_ssl_context_callback;
+    }
+#endif
+
 private:
     web::web_proxy m_proxy;
     web::credentials m_credentials;
     web::http::http_headers m_headers;
     bool m_sni_enabled;
     utf8string m_sni_hostname;
     bool m_validate_certificates;
+#if !defined(_WIN32) || !defined(__cplusplus_winrt)
+    std::function<void(boost::asio::ssl::context&)> m_ssl_context_callback;
+#endif
 };
 
 /// <summary>

Release/src/CMakeLists.txt

@@ -67,6 +67,9 @@ elseif(CPPREST_WEBSOCKETS_IMPL STREQUAL "wspp")
   )
   cpprest_find_websocketpp()
   target_link_libraries(cpprest PRIVATE cpprestsdk_websocketpp_internal)
+  cpprest_find_boost()
+  cpprest_find_openssl()
+  target_link_libraries(cpprest PUBLIC cpprestsdk_boost_internal cpprestsdk_openssl_internal)
 else()
   message(FATAL_ERROR "Invalid implementation")
 endif()

Release/src/websockets/client/ws_client_wspp.cpp

@@ -189,6 +189,10 @@ class wspp_callback_client : public websocket_client_callback_impl,
                     new boost::asio::ssl::context(boost::asio::ssl::context::sslv23));
                 sslContext->set_default_verify_paths();
                 sslContext->set_options(boost::asio::ssl::context::default_workarounds);
+                if (m_config.get_ssl_context_callback())
+                {
+                    m_config.get_ssl_context_callback()(*sslContext);
+                }
                 if (m_config.validate_certificates())
                 {
                     sslContext->set_verify_mode(boost::asio::ssl::context::verify_peer);