#! /home/tak/bin/mytop
(************************************************************
   proxy.ml		Created      : Fri Feb 15 22:18:25 2002
  			Last modified: Sun Feb 09 13:33:12 2003
  FTP Directory: sources/ocaml #
  mytopの作り方
  >  ocamlmktop unix.cma -custom -o mytop
  並列度がなく、ブロックばかりするので、遅いプロキシ
************************************************************)

#use "url.ml"

module Unix = UnixLabels;;

let port = 80

let connect host port =
  let addr = Unix.gethostbyname host in
  let s = 
    Unix.socket ~domain:Unix.PF_INET ~kind:Unix.SOCK_STREAM ~protocol:0 in
  Unix.connect s (Unix.ADDR_INET(addr.Unix.h_addr_list.(0), port)); s

let request_split_regexp = Str.regexp "\\(\r\n\\)+"
let line_split_regexp = Str.regexp " +"

let receive_request s =
  let c = ref "" in
  let buf = String.make 1 '\000' in
  let lf = ref false in
  try
    while true do
      let num = Unix.recv s buf 0 1 [] in
      if num = 0 then
	raise End_of_file
      else
	let ch = String.sub buf 0 num in
	begin
	  c := !c^(String.sub buf 0 num);
	  let size = String.length !c in
	  if size >= 4 then
	    let last = Str.last_chars !c 4 in
	    if last = "\r\n\r\n" then
	      raise End_of_file
	end
    done;
    "hoge"
  with End_of_file -> !c

let receive_message_from_connected_socket s =
  let c = ref "" in
  let buf = String.make 1 '\000' in
  try
    while true do
      let num = Unix.recv s buf 0 1 [] in
      if num = 0 then
	raise End_of_file
      else
	c := !c^(String.sub buf 0 num)
    done;
    "hoge"
  with End_of_file -> !c

let interpret_request request =
  let hd::tl = Str.split request_split_regexp request in
  let m::url::remain = Str.split line_split_regexp hd in
  let u = of_string url in
  let host = u.hostname in
  let path = u.path in
  (host, path)

let session (serv_sock, addr) =
  let request = receive_request serv_sock in
  let _ = print_endline ("PROXY request =====>\n" ^ request) in
  let (host, path) = interpret_request request in
  let sock = connect host port in
  let size = String.length request in
  let _ = Unix.send sock request 0 size [] in
  let reply = receive_message_from_connected_socket sock in
  let _ = print_endline ("PROXY reply <=====\n" ^ reply); flush stdout in
  let reply_size = String.length reply in
  begin
    ignore (Unix.send serv_sock reply 0 reply_size []);
    Unix.shutdown serv_sock Unix.SHUTDOWN_SEND;
  end

let listen_as_server ~host ~port =
  let s = Unix.socket ~domain:Unix.PF_INET ~kind:Unix.SOCK_STREAM ~protocol:0 in
  begin
    Unix.bind s ~addr:(Unix.ADDR_INET(((Unix.gethostbyname host).Unix.h_addr_list).(0),
				      port));
    Unix.listen s ~max:5; (* maxは受け付ける接続数 *)
    while true do
      session (Unix.accept s)
    done
  end;;

(************************************************************
 * メイン
 *
 *
 *)
   
if (Array.length Sys.argv) != 3 then
  print_string "listen [hostname] [port]\n"
else
  listen_as_server Sys.argv.(1) (int_of_string Sys.argv.(2));