Add a simple (single threaded) echo server

echoserver.adb

@@ -0,0 +1,55 @@
+--
+--  Echo server!
+
+private with Ada.Text_IO;
+private with Ada.Streams;
+private with GNAT.Sockets;
+
+use Ada.Text_IO;
+use Ada.Streams;
+use GNAT.Sockets;
+
+procedure echoserver is
+    ServerSock : Socket_Type;
+    ClientSock : Socket_Type;
+    ServerAddr : Sock_Addr_Type;
+
+    Listen_Addr : constant String := "127.0.0.1";
+    Listen_Port : constant Integer := 2046;
+
+
+begin
+    Initialize; -- Initialize the GNAT.Sockets library
+    ServerAddr.Addr := Inet_Addr (Listen_Addr);
+    ServerAddr.Port := Port_Type (Listen_Port);
+
+    Create_Socket (ServerSock);
+    Set_Socket_Option (ServerSock, Socket_Level, (Reuse_Address, True));
+    Put_Line (">>> Starting echo server on port" & Integer'Image (Listen_Port) & " ...");
+
+    Bind_Socket (ServerSock, ServerAddr);
+    Put_Line (".. bound to socket");
+
+    Listen_Socket (ServerSock);
+    Put_Line (".. listening for connections");
+
+    loop
+        Accept_Socket (ServerSock, ClientSock, ServerAddr);
+        Put_Line (".. accepted connection");
+
+        declare
+            Channel : Stream_Access := Stream (ClientSock);
+            Char : Character;
+            Data : Ada.Streams.Stream_Element_Array (1 .. 1);
+            Offset : Ada.Streams.Stream_Element_Count;
+        begin
+            while true loop
+                Ada.Streams.Read (Channel.All, Data, Offset);
+                exit when Offset = 0;
+                Put (Character'Val (Data (1)));
+            end loop;
+            Put_Line (".. closing connection");
+            Close_Socket (ClientSock);
+        end;
+    end loop;
+end;