Update to handle enable/disable of TLSv1_3

Update to handle enable/disable of TLSv1_3

src/Abstract_Socket.cc

@@ -1980,6 +1980,7 @@ SSL_Socket::SSL_Socket()
   TLSv1=true;
   TLSv1_1=true;
   TLSv1_2=true;
+  TLSv1_3=true; 
 }
 
 SSL_Socket::SSL_Socket(const char *tp_type, const char *tp_name)
@@ -2003,6 +2004,7 @@ SSL_Socket::SSL_Socket(const char *tp_type, const char *tp_name)
   TLSv1=true;
   TLSv1_1=true;
   TLSv1_2=true;
+  TLSv1_3=true; 
 }
 
 SSL_Socket::~SSL_Socket()
@@ -2075,6 +2077,10 @@ bool SSL_Socket::parameter_set(const char *parameter_name,
     if(strcasecmp(parameter_value, "yes") == 0) TLSv1_2 = false;
     else if(strcasecmp(parameter_value, "no") == 0) TLSv1_2 = true;
     else log_error("Parameter value '%s' not recognized for parameter '%s'", parameter_value, ssl_disable_TLSv1_2());
+  } else if(strcasecmp(parameter_name, ssl_disable_TLSv1_3()) == 0) { 
+    if(strcasecmp(parameter_value, "yes") == 0) TLSv1_3 = false;
+    else if(strcasecmp(parameter_value, "no") == 0) TLSv1_3 = true;
+    else log_error("Parameter value '%s' not recognized for parameter '%s'", parameter_value, ssl_disable_TLSv1_3());
   } else {
     log_debug("leaving SSL_Socket::parameter_set(%s, %s)", parameter_name, parameter_value);
     return Abstract_Socket::parameter_set(parameter_name, parameter_value);
@@ -2126,6 +2132,11 @@ bool SSL_Socket::add_user_data(int client_id) {
     SSL_set_options(ssl_current_ssl,SSL_OP_NO_TLSv1_2);
   }
 #endif
+#ifdef SSL_OP_NO_TLSv1_3
+  if(!TLSv1_3){
+    SSL_set_options(ssl_current_ssl,SSL_OP_NO_TLSv1_3);
+  }
+#endif
     
   set_user_data(client_id, ssl_current_ssl);
   log_debug("New client added with key '%d'", client_id);
@@ -2551,6 +2562,7 @@ const char* SSL_Socket::ssl_disable_SSLv3()      { return "ssl_disable_SSLv3";}
 const char* SSL_Socket::ssl_disable_TLSv1()      { return "ssl_disable_TLSv1";}
 const char* SSL_Socket::ssl_disable_TLSv1_1()      { return "ssl_disable_TLSv1_1";}
 const char* SSL_Socket::ssl_disable_TLSv1_2()      { return "ssl_disable_TLSv1_2";}
+const char* SSL_Socket::ssl_disable_TLSv1_3()      { return "ssl_disable_TLSv1_3";} 
 
 
 void SSL_Socket::ssl_actions_to_seed_PRNG() {