src/comm/TcpAcceptor.h

   1 /*
   2  * Copyright (C) 1996-2025 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_SRC_COMM_TCPACCEPTOR_H
  10 #define SQUID_SRC_COMM_TCPACCEPTOR_H
  11
  12 #include "anyp/forward.h"
  13 #include "base/AsyncJob.h"
  14 #include "base/CbcPointer.h"
  15 #include "base/Subscription.h"
  16 #include "comm/Flag.h"
  17 #include "comm/forward.h"
  18
  19 class CommCloseCbParams;
  20
  21 namespace Comm
  22 {
  23
  24 class AcceptLimiter;
  25
  26 /**
  27  * Listens on a Comm::Connection for new incoming connections and
  28  * emits an active Comm::Connection descriptor for the new client.
  29  *
  30  * Handles all event limiting required to quash inbound connection
  31  * floods within the global FD limits of available Squid_MaxFD and
  32  * client_ip_max_connections.
  33  *
  34  * Fills the emitted connection with all connection details able to
  35  * be looked up. Currently these are the local/remote IP:port details
  36  * and the listening socket transparent-mode flag.
  37  */
  38 class TcpAcceptor : public AsyncJob
  39 {
  40     CBDATA_CHILD(TcpAcceptor);
  41
  42 public:
  43     typedef CbcPointer<Comm::TcpAcceptor> Pointer;
  44
  45 private:
  46     void start() override;
  47     bool doneAll() const override;
  48     void swanSong() override;
  49     const char *status() const override;
  50
  51     TcpAcceptor(const TcpAcceptor &); // not implemented.
  52
  53 public:
  54     TcpAcceptor(const Comm::ConnectionPointer &conn, const char *note, const Subscription::Pointer &aSub);
  55     TcpAcceptor(const AnyP::PortCfgPointer &listenPort, const char *note, const Subscription::Pointer &aSub);
  56
  57 protected:
  58     /** Subscribe a handler to receive calls back about new connections.
  59      * Unsubscribes any existing subscribed handler.
  60      */
  61     void subscribe(const Subscription::Pointer &aSub);
  62
  63     /** Remove the currently waiting callback subscription.
  64      * Already scheduled callbacks remain scheduled.
  65      */
  66     void unsubscribe(const char *reason);
  67
  68     /** Try and accept another connection (synchronous).
  69      * If one is pending already the subscribed callback handler will be scheduled
  70      * to handle it before this method returns.
  71      */
  72     void acceptNext();
  73
  74     /// Call the subscribed callback handler with details about a new connection.
  75     void notify(const Comm::Flag flag, const Comm::ConnectionPointer &details) const;
  76
  77     /// errno code of the last accept() or listen() action if one occurred.
  78     int errcode;
  79
  80     /// Method to test if there are enough file descriptors to open a new client connection
  81     /// if not the accept() will be postponed
  82     static bool okToAccept();
  83
  84     friend class AcceptLimiter;
  85
  86 private:
  87     Subscription::Pointer theCallSub;    ///< used to generate AsyncCalls handling our events.
  88
  89     /// conn being listened on for new connections
  90     /// Reserved for read-only use.
  91     ConnectionPointer conn;
  92
  93     /// configuration details of the listening port (if provided)
  94     AnyP::PortCfgPointer listenPort_;
  95
  96     /// listen socket closure handler
  97     AsyncCall::Pointer closer_;
  98
  99     /// Method callback for whenever an FD is ready to accept a client connection.
 100     static void doAccept(int fd, void *data);
 101
 102     void acceptOne();
 103     bool acceptInto(Comm::ConnectionPointer &);
 104     void setListen();
 105     void handleClosure(const CommCloseCbParams &io);
 106     /// whether we are listening on one of the squid.conf *ports
 107     bool intendedForUserConnections() const { return bool(listenPort_); }
 108     void logAcceptError(const ConnectionPointer &tcpClient) const;
 109 };
 110
 111 } // namespace Comm
 112
 113 #endif /* SQUID_SRC_COMM_TCPACCEPTOR_H */
 114