Allow setting additional openssl CTX options from client applications (#600)

ixwebsocket/IXSocketOpenSSL.cpp

@@ -561,6 +561,11 @@ namespace ix
             return false;
         }
 
+        if (_tlsOptions.hasAdditionalOptions())
+        {
+            SSL_CTX_set_options(_ssl_context, _tlsOptions.additional_openssl_ctx_options);
+        }
+
         return true;
     }
 
@@ -598,7 +603,7 @@ namespace ix
                         SSL_CTX_set_mode(_ssl_context, SSL_MODE_ENABLE_PARTIAL_WRITE);
                         SSL_CTX_set_mode(_ssl_context, SSL_MODE_ACCEPT_MOVING_WRITE_BUFFER);
                         SSL_CTX_set_options(_ssl_context,
-                                            SSL_OP_ALL | SSL_OP_NO_SSLv2 | SSL_OP_NO_SSLv3);
+                                            SSL_OP_ALL | SSL_OP_NO_SSLv2 | SSL_OP_NO_SSLv3 | _tlsOptions.additional_openssl_ctx_options);
                     }
                 }
             }

ixwebsocket/IXSocketTLSOptions.cpp

@@ -49,6 +49,11 @@ namespace ix
         return true;
     }
 
+    bool SocketTLSOptions::hasAdditionalOptions() const
+    {
+        return additional_openssl_ctx_options != 0;
+    }
+
     bool SocketTLSOptions::hasCertAndKey() const
     {
         return !certFile.empty() && !keyFile.empty();

ixwebsocket/IXSocketTLSOptions.h

@@ -36,6 +36,11 @@ namespace ix
         // whether to skip validating the peer's hostname against the certificate presented
         bool disable_hostname_validation = false;
 
+        // additional OpenSSL CTX options to set when calling SSL_CTX_set_options during the handshake
+        uint64_t additional_openssl_ctx_options = 0;
+
+        bool hasAdditionalOptions() const;
+
         bool hasCertAndKey() const;
 
         bool isUsingSystemDefaults() const;