Rename headers to .hpp (#1154)

Fixes #1153

src/web/Resolver.hpp

@@ -0,0 +1,63 @@
+//------------------------------------------------------------------------------
+/*
+    This file is part of clio: https://github.com/XRPLF/clio
+    Copyright (c) 2023, the clio developers.
+
+    Permission to use, copy, modify, and distribute this software for any
+    purpose with or without fee is hereby granted, provided that the above
+    copyright notice and this permission notice appear in all copies.
+
+    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
+    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+    ANY  SPECIAL,  DIRECT,  INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
+    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+//==============================================================================
+
+#pragma once
+
+#include <boost/asio.hpp>
+#include <boost/asio/io_context.hpp>
+#include <boost/asio/ip/tcp.hpp>
+
+#include <concepts>
+#include <string>
+#include <string_view>
+#include <vector>
+
+namespace web {
+
+template <typename T>
+concept SomeResolver = requires(T t) {
+    std::is_default_constructible_v<T>;
+    {
+        t.resolve(std::string_view{}, std::string_view{})
+    } -> std::same_as<std::vector<std::string>>;
+};
+
+/**
+ * @brief Simple hostnames to IP addresses resolver.
+ */
+class Resolver {
+public:
+    /**
+     * @brief Resolve hostname to IP addresses.
+     *
+     * @throw This method throws an exception when the hostname cannot be resolved.
+     *
+     * @param hostname Hostname to resolve
+     * @param service Service to resolve (could be empty or port number or http)
+     * @return std::vector<std::string> IP addresses of the hostname
+     */
+    std::vector<std::string>
+    resolve(std::string_view hostname, std::string_view service = "");
+
+private:
+    boost::asio::io_context ioContext_;
+    boost::asio::ip::tcp::resolver resolver_{ioContext_};
+};
+
+}  // namespace web