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// Protocol support for RFC 6455 
// 
// $Id$ 
// 
// 2018-09-27 Henrik Grubbström 
 
inherit "module"; 
 
#include <module.h> 
#include <request_trace.h> 
 
constant cvs_version = "$Id$"; 
constant thread_safe = 1; 
constant module_name = "WebSockets: Protocol support"; 
constant module_type = MODULE_FIRST; 
constant module_doc  = "Adds support for the HTTP extension defined " 
  "in <a href='http://rfc.roxen.com/6455'>RFC 6455 (WebSocket)</a>."; 
constant module_unique = 1; 
 
#ifdef WS_DEBUG 
#define WS_WERROR(X...)     werror(X) 
#else /* !WS_DEBUG */ 
#define WS_WERROR(X...) 
#endif /* WS_DEBUG */ 
 
Configuration conf; 
 
void create() 
{ 
} 
 
void start(int q, Configuration c) 
{ 
  conf = c; 
} 
 
protected int is_connection_upgrade(string path, RequestID id) 
{ 
  return has_value(lower_case(id->request_headers->connection||"")/",", 
                   "upgrade"); 
} 
 
protected int is_upgrade_websocket(string path, RequestID id) 
{ 
  return has_value(lower_case(id->request_headers->upgrade||"")/",", 
                   "websocket"); 
} 
 
protected int is_websocket_version_13(string path, RequestID id) 
{ 
  return id->request_headers["sec-websocket-version"] == "13"; 
} 
 
protected int has_valid_websocket_key(string path, RequestID id) 
{ 
  string raw_key = ""; 
  catch { 
    raw_key = MIME.decode_base64(id->request_headers["sec-websocket-key"]); 
  }; 
  return sizeof(raw_key) >= 16; 
} 
 
// Operation: 
// 
// * For syntactically valid WebSocket requests, the 
//   method field in the RequestID is set to "WebSocketOpen", 
//   the default error_code set to HTTP_BAD and zero returned. 
// 
// * For requests that don't seem to be WebSocket requests 
//   nothing is done, and zero is returned. 
// 
// * For requests that are upgrade requests to other than 
//   websockets, the default error_code is set to HTTP_BAD, 
//   and zero returned. 
// 
// * For other invalid requests an appropriate HTTP_BAD 
//   error status is returned. 
// 
// This means that modules implementing support for WebSockets 
// need to check for the method "WebSocketOpen", and then 
// return Roxen.upgrade_to_websocket() if appropriate. 
 
mapping(string:mixed)|int(-1..0) first_try(RequestID id) 
{ 
  TRACE_ENTER("Checking if this is a valid websocket request...", this); 
  if (id->misc->internal_get) { 
    TRACE_LEAVE("No - internal request."); 
    return 0; 
  } 
 
  if (id->method != "GET") { 
    TRACE_LEAVE("No - wrong method."); 
    return 0; 
  } 
 
  id->register_vary_callback("connection", is_connection_upgrade); 
 
  if (!is_connection_upgrade("", id)) { 
    TRACE_LEAVE("No - no connection: upgrade."); 
    return 0; 
  } 
 
  id->register_vary_callback("connection", is_upgrade_websocket); 
 
  if (!is_upgrade_websocket("", id)) { 
    // Unsupported upgrade header. 
    id->misc->error_code = id->misc->error_code || Protocols.HTTP.HTTP_BAD; 
    TRACE_LEAVE("No - Unsupported or missing upgrade header."); 
    return 0; 
  } 
 
  id->register_vary_callback("sec-websocket-version", is_websocket_version_13); 
 
  if (!is_websocket_version_13("", id)) { 
    // Unsupported WebSocket version. 
    TRACE_LEAVE("No - Unsupported websocket version."); 
    return Roxen.http_status(Protocols.HTTP.HTTP_BAD, 
                             "Unsupported WebSocket version.") + ([ 
      "extra_heads": ([ 
        "Sec-WebSocket-Version": (string)13/*Protocols.WebSocket.websocket_version*/, 
      ]), 
    ]); 
  } 
 
  id->register_vary_callback("sec-websocket-key", has_valid_websocket_key); 
 
  if (!has_valid_websocket_key("", id)) { 
    // Invalid Sec-WebSocet-Key. 
    TRACE_LEAVE("No - Invalid Sec-WebSocket-Key."); 
    return Roxen.http_status(Protocols.HTTP.HTTP_BAD, 
                             "Invalid Sec-WebSocket-Key."); 
  } 
 
  // FIXME: Fix vary support for http version. 
  if (!has_prefix(id->prot, "HTTP/") || 
      (id->prot[sizeof("HTTP/")..] < "1.1")) { 
    // HTTP/1.1 or later required. 
    NOCACHE(); 
    TRACE_LEAVE("No - not HTTP/1.1 or later."); 
    return 0; 
  } 
 
  TRACE_LEAVE("Yes."); 
 
  // NB: The mixed case in the method ensures that it can't be 
  //     set directly from the http request. 
  id->method = "WebSocketOpen"; 
  id->misc->error_code = Protocols.HTTP.HTTP_BAD; 
 
  // Continue request processing. 
  return 0; 
}