src/HttpControlMsg.h

   1 /*
   2  * Copyright (C) 1996-2015 The Squid Software Foundation and contributors
   3  *
   4  * Squid software is distributed under GPLv2+ license and includes
   5  * contributions from numerous individuals and organizations.
   6  * Please see the COPYING and CONTRIBUTORS files for details.
   7  */
   8
   9 #ifndef SQUID_HTTP_CONTROL_MSG_H
  10 #define SQUID_HTTP_CONTROL_MSG_H
  11
  12 #include "base/AsyncCall.h"
  13 #include "HttpReply.h"
  14
  15 class HttpControlMsg;
  16
  17 /*
  18  * This API exists to throttle forwarding of 1xx messages from the server
  19  * side (Source == HttpStateData) to the client side (Sink == ConnStateData).
  20  *
  21  * Without throttling, Squid would have to drop some 1xx responses to
  22  * avoid DoS attacks that send many 1xx responses without reading them.
  23  * Dropping 1xx responses without violating HTTP is as complex as throttling.
  24  */
  25
  26 /// sends a single control message, notifying the Sink
  27 class HttpControlMsgSink: public virtual AsyncJob
  28 {
  29 public:
  30     HttpControlMsgSink(): AsyncJob("unused") {}
  31
  32     /// called to send the 1xx message and notify the Source
  33     virtual void sendControlMsg(HttpControlMsg msg) = 0;
  34 };
  35
  36 /// bundles HTTP 1xx reply and the "successfully forwarded" callback
  37 class HttpControlMsg
  38 {
  39 public:
  40     typedef AsyncCall::Pointer Callback;
  41
  42     HttpControlMsg(const HttpReply::Pointer &aReply, const Callback &aCallback):
  43         reply(aReply), cbSuccess(aCallback) {}
  44
  45 public:
  46     HttpReply::Pointer reply; ///< the 1xx message being forwarded
  47     Callback cbSuccess; ///< called after successfully writing the 1xx message
  48
  49     // We could add an API to notify of send failures as well, but the
  50     // current Source and Sink are tied via Store anyway, so the Source
  51     // will know, eventually, if the Sink is gone or otherwise failed.
  52 };
  53
  54 inline std::ostream &
  55 operator <<(std::ostream &os, const HttpControlMsg &msg)
  56 {
  57     return os << msg.reply << ", " << msg.cbSuccess;
  58 }
  59
  60 #endif /* SQUID_HTTP_CONTROL_MSG_H */
  61