src/HttpControlMsg.h

   1 /*
   2  * Copyright (C) 1996-2023 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 CommIoCbParams;
  16 class HttpControlMsg;
  17
  18 /*
  19  * This API exists to throttle forwarding of 1xx messages from the server
  20  * side (Source == HttpStateData) to the client side (Sink == ConnStateData).
  21  *
  22  * Without throttling, Squid would have to drop some 1xx responses to
  23  * avoid DoS attacks that send many 1xx responses without reading them.
  24  * Dropping 1xx responses without violating HTTP is as complex as throttling.
  25  */
  26
  27 /// sends a single control message, notifying the Sink
  28 class HttpControlMsgSink: public virtual AsyncJob
  29 {
  30 public:
  31     HttpControlMsgSink(): AsyncJob("unused") {}
  32
  33     /// called to send the 1xx message and notify the Source
  34     virtual void sendControlMsg(HttpControlMsg msg) = 0;
  35
  36     virtual void doneWithControlMsg();
  37
  38     /// callback to handle Comm::Write completion
  39     void wroteControlMsg(const CommIoCbParams &);
  40
  41     /// Call to schedule when the control msg has been sent
  42     AsyncCall::Pointer cbControlMsgSent;
  43 };
  44
  45 /// bundles HTTP 1xx reply and the "successfully forwarded" callback
  46 class HttpControlMsg
  47 {
  48 public:
  49     typedef AsyncCall::Pointer Callback;
  50
  51     HttpControlMsg(const HttpReply::Pointer &aReply, const Callback &aCallback):
  52         reply(aReply), cbSuccess(aCallback) {}
  53
  54 public:
  55     HttpReply::Pointer reply; ///< the 1xx message being forwarded
  56     Callback cbSuccess; ///< called after successfully writing the 1xx message
  57
  58     // We could add an API to notify of send failures as well, but the
  59     // current Source and Sink are tied via Store anyway, so the Source
  60     // will know, eventually, if the Sink is gone or otherwise failed.
  61 };
  62
  63 inline std::ostream &
  64 operator <<(std::ostream &os, const HttpControlMsg &msg)
  65 {
  66     return os << msg.reply << ", " << msg.cbSuccess;
  67 }
  68
  69 #endif /* SQUID_HTTP_CONTROL_MSG_H */
  70