add lisener for socket

include/net/ListenerPlan.hpp

@@ -0,0 +1,60 @@
+/*********************************/
+/*                               */
+/*     o.riabenkyi@gmail.com     */
+/*                               */
+/*********************************/
+
+#ifndef LISTENERPLAN_HPP
+#define LISTENERPLAN_HPP
+
+#include <sys/socket.h>
+
+#include <exception>
+#include <string>
+#include <vector>
+
+#include "config/Config.hpp"
+
+namespace webserv {
+
+// Turns a validated Config into the deduplicated set of sockets the server
+// must bind. Two server blocks may list the same host:port to share one
+// socket (virtual hosting, picked apart later by server_name), so this
+// groups listen directives by unique host:port instead of binding one
+// socket per directive, which would make the second bind() fail.
+//
+// The ServerConfig pointers in routes() point into the Config passed to
+// build(); that Config must outlive the ListenerPlan.
+class ListenerPlan final {
+  public:
+    class Error : public std::exception {
+      public:
+        explicit Error(std::string message);
+        const char* what() const noexcept override;
+
+      private:
+        std::string msg_;
+    };
+
+    static ListenerPlan build(const Config& config);
+
+    const std::vector<sockaddr_storage>& endpoints() const noexcept {
+      return endpoints_;
+    }
+
+    // routes()[i] lists, in config order, every ServerConfig reachable
+    // through endpoints()[i]. Not consumed yet: it becomes the input to
+    // Host-header based virtual host selection once HTTP request routing
+    // exists.
+    const std::vector<std::vector<const ServerConfig*>>& routes() const noexcept {
+      return routes_;
+    }
+
+  private:
+    std::vector<sockaddr_storage> endpoints_;
+    std::vector<std::vector<const ServerConfig*>> routes_;
+};
+
+}  // namespace webserv
+
+#endif