MXS-1220: Create HTTP response class

The HTTP response class simplifies the response creation. The next step is
to add generation of all the default headers that are needed by the REST
API.

server/core/httpresponse.cc

@@ -0,0 +1,75 @@
+/*
+ * Copyright (c) 2016 MariaDB Corporation Ab
+ *
+ * Use of this software is governed by the Business Source License included
+ * in the LICENSE.TXT file and at www.mariadb.com/bsl11.
+ *
+ * Change Date: 2019-07-01
+ *
+ * On the date above, in accordance with the Business Source License, use
+ * of this software will be governed by version 2 or later of the General
+ * Public License.
+ */
+
+#include "maxscale/httpresponse.hh"
+
+#include <new>
+#include <string>
+#include <sstream>
+
+#include <maxscale/alloc.h>
+#include <sys/time.h>
+
+using std::string;
+using std::stringstream;
+
+HttpResponse::HttpResponse(string response, enum http_code code):
+    m_body(response),
+    m_code(code)
+{
+}
+
+HttpResponse* HttpResponse::create(json_t* response, enum http_code code)
+{
+    HttpResponse* rval = NULL;
+    char* json = json_dumps(response, 0);
+
+    if (json)
+    {
+        rval = HttpResponse::create(json, code);
+        MXS_FREE(json);
+    }
+
+    return rval;
+}
+
+HttpResponse* HttpResponse::create(string response, enum http_code code)
+{
+    return new (std::nothrow) HttpResponse(response, code);
+}
+
+HttpResponse::~HttpResponse()
+{
+}
+
+void HttpResponse::add_header(string name, string value)
+{
+    m_headers[name] = value;
+}
+
+string HttpResponse::get_response() const
+{
+    stringstream response;
+    response << "HTTP/1.1 " << http_code_to_string(m_code);
+
+    for (map<string, string>::const_iterator it = m_headers.begin();
+         it != m_headers.end(); it++)
+    {
+        response << it->first << ": " << it->second << "\r\n";
+    }
+
+    /** End of headers, add the body */
+    response << "\r\n" <<  m_body;
+
+    return response.str();
+}