libmicrohttpd2

mhd_daemon.h (30891B)

---

 /* SPDX-License-Identifier: LGPL-2.1-or-later OR (GPL-2.0-or-later WITH eCos-exception-2.0) */
 /*
   This file is part of GNU libmicrohttpd.
   Copyright (C) 2024 Evgeny Grin (Karlson2k)
 
   GNU libmicrohttpd is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.
 
   GNU libmicrohttpd is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.
 
   Alternatively, you can redistribute GNU libmicrohttpd and/or
   modify it under the terms of the GNU General Public License as
   published by the Free Software Foundation; either version 2 of
   the License, or (at your option) any later version, together
   with the eCos exception, as follows:
 
     As a special exception, if other files instantiate templates or
     use macros or inline functions from this file, or you compile this
     file and link it with other works to produce a work based on this
     file, this file does not by itself cause the resulting work to be
     covered by the GNU General Public License. However the source code
     for this file must still be made available in accordance with
     section (3) of the GNU General Public License v2.
 
     This exception does not invalidate any other reasons why a work
     based on this file might be covered by the GNU General Public
     License.
 
   You should have received copies of the GNU Lesser General Public
   License and the GNU General Public License along with this library;
   if not, see <https://www.gnu.org/licenses/>.
 */
 
 /**
  * @file src/mhd2/mhd_daemon.h
  * @brief  The header for declaration of struct MHD_Daemon
  * @author Karlson2k (Evgeny Grin)
  */
 
 #ifndef MHD_DAEMON_H
 #define MHD_DAEMON_H 1
 
 #include "mhd_sys_options.h"
 
 #include "sys_bool_type.h"
 #include "sys_base_types.h"
 
 #include "mhd_dlinked_list.h"
 
 #include "mhd_buffer.h"
 #include "mhd_socket_type.h"
 #include "mhd_atomic_counter.h"
 
 #ifdef MHD_SUPPORT_AUTH_DIGEST
 #  include "mhd_digest_auth_data.h"
 #endif
 
 #ifdef MHD_SUPPORT_HTTPS
 #  include "mhd_tls_choice.h"
 #endif
 
 #ifdef MHD_SUPPORT_THREADS
 #  include "mhd_threads.h"
 #  include "mhd_itc_types.h"
 #endif
 
 #include "mhd_locks.h"
 
 #include "sys_select.h"
 #include "sys_poll.h"
 #ifdef MHD_SUPPORT_EPOLL
 #  include <sys/epoll.h>
 #endif
 
 #include "mempool_types.h"
 
 #include "mhd_public_api.h"
 
 struct DaemonOptions; /* Forward declaration */
 struct MHD_Connection; /* Forward declaration */
 
 /**
  * The helper struct for the connections list
  */
 mhd_DLINKEDL_LIST_DEF (MHD_Connection);
 
 /**
  * The current phase of the daemon life
  */
 enum MHD_FIXED_ENUM_ mhd_DaemonState
 {
   /**
    * The daemon has been created, but not yet started.
    * Setting configuration options is possible.
    */
   mhd_DAEMON_STATE_NOT_STARTED = 0
   ,
   /**
    * The daemon is being started.
    */
   mhd_DAEMON_STATE_STARTING
   ,
   /**
    * The daemon has been started.
    * Normal operations.
    */
   mhd_DAEMON_STATE_STARTED
   ,
   /**
    * The daemon has failed to start
    */
   mhd_DAEMON_STATE_FAILED
   ,
   /**
    * The daemon is being stopped.
    */
   mhd_DAEMON_STATE_STOPPING
   ,
   /**
    * The daemon is stopped.
    * The state should rarely visible as daemon should be destroyed when stopped.
    */
   mhd_DAEMON_STATE_STOPPED
 };
 
 
 /**
  * Internal version of the daemon work mode type
  */
 enum MHD_FIXED_ENUM_ mhd_WorkModeIntType
 {
   /**
    * Network edge-triggered events are monitored and provided by application.
    * Receiving, sending and processing of the network data if performed when
    * special MHD function is called by application.
    * No threads managed by the daemon.
    */
   mhd_WM_INT_EXTERNAL_EVENTS_EDGE
   ,
   /**
    * Network level-triggered events are monitored and provided by application.
    * Receiving, sending and processing of the network data if performed when
    * special MHD function is called by application.
    * No threads managed by the daemon.
    */
   mhd_WM_INT_EXTERNAL_EVENTS_LEVEL
   ,
   /**
    * The daemon checks for the network events, receives, sends and process
    * the network data when special MHD function is called by application.
    * No threads managed by the daemon.
    */
   mhd_WM_INT_INTERNAL_EVENTS_NO_THREADS
 #ifdef MHD_SUPPORT_THREADS
   ,
   /**
    * The daemon runs its own single thread, where the daemon monitors
    * all network events, receives, sends and process the network data.
    */
   mhd_WM_INT_INTERNAL_EVENTS_ONE_THREAD
   ,
   /**
    * The daemon runs its own single thread, where the daemon monitors
    * the new incoming connections, and runs individual thread for each
    * established connection, where the daemon monitors connection, receives,
    * sends and process the network data.
    */
   mhd_WM_INT_INTERNAL_EVENTS_THREAD_PER_CONNECTION
   ,
   /**
    * The daemon runs its fixed number of threads, all threads monitors the
    * new incoming connections and each thread handles own subset of the network
    * connections (monitors connections network events, receives, sends and
    * process the network data).
    */
   mhd_WM_INT_INTERNAL_EVENTS_THREAD_POOL
 #endif
 };
 
 #ifdef MHD_SUPPORT_THREADS
 /**
  * Check whether given mhd_WorkModeIntType value should have internal threads,
  * either directly controlled or indirectly, via additional workers daemons.
  */
 #  define mhd_WM_INT_HAS_THREADS(wm_i) \
         (mhd_WM_INT_INTERNAL_EVENTS_ONE_THREAD <= wm_i)
 /**
  * Check whether given mhd_WorkModeIntType value equals "thread-per-connection"
  */
 #  define mhd_WM_INT_IS_THREAD_PER_CONN(wm_i) \
         (mhd_WM_INT_INTERNAL_EVENTS_THREAD_PER_CONNECTION == wm_i)
 /**
  * Check whether given mhd_WorkModeIntType value equals "thread pool"
  */
 #  define mhd_WM_INT_IS_THREAD_POOL(wm_i) \
         (mhd_WM_INT_INTERNAL_EVENTS_THREAD_POOL == wm_i)
 #else  /* ! MHD_SUPPORT_THREADS */
 #  define mhd_WM_INT_HAS_THREADS(wm_i)          (0)
 #  define mhd_WM_INT_IS_THREAD_PER_CONN(wm_i)   (0)
 #  define mhd_WM_INT_IS_THREAD_POOL(wm_i)       (0)
 #endif /* ! MHD_SUPPORT_THREADS */
 
 /**
  * Check whether given mhd_WorkModeIntType value has external events
  */
 #define mhd_WM_INT_HAS_EXT_EVENTS(wm_i) \
         (mhd_WM_INT_EXTERNAL_EVENTS_LEVEL >= wm_i)
 
 
 /**
  * Sockets polling internal syscalls used by MHD.
  *
  * The same value used as by #MHD_SockPollSyscall, however instead of "auto"
  * method this enum uses "not yet set" and enum is extended with an additional
  * "external" value.
  */
 enum MHD_FIXED_ENUM_ mhd_IntPollType
 {
   /**
    * External sockets polling is used.
    */
   mhd_POLL_TYPE_EXT = -1
   ,
   /**
    * Internal sockets polling syscall has not been selected yet.
    */
   mhd_POLL_TYPE_NOT_SET_YET = MHD_SPS_AUTO
   ,
   /**
    * Use select().
    */
   mhd_POLL_TYPE_SELECT = MHD_SPS_SELECT
   ,
   /**
    * Use poll().
    */
   mhd_POLL_TYPE_POLL = MHD_SPS_POLL
 #ifdef MHD_SUPPORT_EPOLL
   ,
   /**
    * Use epoll.
    */
   mhd_POLL_TYPE_EPOLL = MHD_SPS_EPOLL
 #endif /* MHD_SUPPORT_EPOLL */
 };
 
 
 #ifdef MHD_SUPPORT_EPOLL
 /**
  * Check whether provided mhd_IntPollType value is "epoll"
  */
 #  define mhd_POLL_TYPE_INT_IS_EPOLL(poll_type) \
         (mhd_POLL_TYPE_EPOLL == poll_type)
 #else
 #  define mhd_POLL_TYPE_INT_IS_EPOLL(poll_type) (0)
 #endif
 
 #if defined(HAVE_UINTPTR_T)
 typedef uintptr_t mhd_SockRelMarker;
 #else
 typedef unsigned char *mhd_SockRelMarker;
 #endif
 
 
 #define mhd_SOCKET_REL_MARKER_EMPTY    ((mhd_SockRelMarker) (0))
 
 #define mhd_SOCKET_REL_MARKER_ITC      ((mhd_SockRelMarker) (-1))
 
 #define mhd_SOCKET_REL_MARKER_LISTEN   (mhd_SOCKET_REL_MARKER_ITC - 1)
 /**
  * Identifier of the FD related to event
  */
 union mhd_SocketRelation
 {
   /**
    * Identifier of the FD.
    * Only valid when it is equal to #mhd_SOCKET_REL_MARKER_EMPTY,
    * #mhd_SOCKET_REL_MARKER_ITC or #mhd_SOCKET_REL_MARKER_LISTEN.
    */
   mhd_SockRelMarker fd_id;
   /**
    * This is a connection's FD.
    * This is valid only when @a fd_id is not valid.
    */
   struct MHD_Connection *connection;
 };
 
 #ifdef MHD_SUPPORT_SELECT
 
 /**
  * Daemon's pointers to the preallocated arrays for running sockets monitoring
  * by poll().
  */
 struct mhd_DaemonEventsSelectData
 {
   /**
    * Set of sockets monitored for read (receive) readiness.
    */
   fd_set *rfds;
   /**
    * Set of sockets monitored for write (send) readiness.
    */
   fd_set *wfds;
   /**
    * Set of sockets monitored for exception (error) readiness.
    */
   fd_set *efds;
 };
 
 #endif /* MHD_SUPPORT_SELECT */
 
 #ifdef MHD_SUPPORT_POLL
 
 /**
  * Daemon's pointers to the preallocated arrays for running sockets monitoring
  * by poll().
  */
 struct mhd_DaemonEventsPollData
 {
   /**
    * Array of sockets monitored for read (receive) readiness.
    * The size of the array is maximum number of connections per this daemon plus
    * two (one for the listen socket and one for ITC).
    * ITC FDs and the listening are always the first (and the second), if used.
    * The number of elements is always two plus maximum number of connections
    * allowed for the daemon.
    */
   struct pollfd *fds;
   /**
    * Array of the @a fds identifications.
    * Each slot matches the slot with the same number in @a fds.
    * Up to two first positions reserved for the ITC and the listening.
    * The number of elements is always two plus maximum number of connections
    * allowed for the daemon.
    */
   union mhd_SocketRelation *rel;
 };
 
 #endif /* MHD_SUPPORT_POLL */
 
 #ifdef MHD_SUPPORT_EPOLL
 /**
  * Daemon's parameters and pointers to the preallocated memory for running
  * sockets monitoring by epoll.
  */
 struct mhd_DaemonEventsEPollData
 {
   /**
    * The epoll control FD.
    */
   int e_fd;
   /**
    * The array of events reported by epoll.
    */
   struct epoll_event *events;
 
   /**
    * The number of elements in the allocated @a events arrays.
    */
   size_t num_elements;
 };
 
 #endif
 
 /**
  * Daemon's data for external events callback.
  * Internal version of struct MHD_WorkModeExternalEventLoopCBParam.
  */
 struct mhd_DaemonEventsExternalCallback
 {
   /**
    * Socket registration callback
    */
   MHD_SocketRegistrationUpdateCallback cb;
   /**
    * Closure for the @a cb
    */
   void *cls;
 };
 
 
 #ifdef MHD_SUPPORT_THREADS
 /**
  * External events data for ITC FD
  */
 struct mhd_DaemonEventsExternalDaemonItcData
 {
   /**
    * Application context for ITC FD
    */
   void *app_cntx;
 
   /**
    * Set to 'true' when active state was detected on ITC by
    * external polling
    */
   bool is_active;
 
   /**
    * Set to 'true' when error state was detected on ITC by
    * external polling.
    * The daemon may become non-functional.
    */
   bool is_broken;
 };
 #endif /* MHD_SUPPORT_THREADS */
 
 /**
  * External events data for the listen socket
  */
 struct mhd_DaemonEventsExternalDaemonListenData
 {
   /**
    * Application context for ITC FD
    */
   void *app_cntx;
 };
 
 /**
  * Daemon's data for external events for sockets monitoring.
  */
 struct mhd_DaemonEventsExternal
 {
   /**
    * Daemon's data for external events callback.
    * Internal version of struct MHD_WorkModeExternalEventLoopCBParam.
    */
   struct mhd_DaemonEventsExternalCallback cb_data;
 
 #ifdef MHD_SUPPORT_THREADS
   /**
    * External events data for ITC FD
    */
   struct mhd_DaemonEventsExternalDaemonItcData itc_data;
 #endif /* MHD_SUPPORT_THREADS */
 
   /**
    * External events data for the listen socket
    */
   struct mhd_DaemonEventsExternalDaemonListenData listen_data;
 
   /**
    * If set to 'true' then all FDs must be registered each round.
    * If set to 'false' then only changed FDs must be registered.
    */
   bool reg_all;
 };
 
 /**
  * Type-specific events monitoring data
  */
 union mhd_DaemonEventMonitoringTypeSpecificData
 {
 #ifdef MHD_SUPPORT_SELECT
   /**
    * Daemon's pointers to the preallocated arrays for running sockets monitoring
    * by poll().
    */
   struct mhd_DaemonEventsSelectData select;
 #endif /* MHD_SUPPORT_SELECT */
 
 #ifdef MHD_SUPPORT_POLL
   /**
    * Daemon's pointers to the preallocated arrays for running sockets monitoring
    * by poll().
    */
   struct mhd_DaemonEventsPollData poll;
 #endif /* MHD_SUPPORT_POLL */
 
 #ifdef MHD_SUPPORT_EPOLL
   /**
    * Daemon's parameters and pointers to the preallocated memory for running
    * sockets monitoring by epoll.
    */
   struct mhd_DaemonEventsEPollData epoll;
 #endif
 
   /**
    * Daemon's data for external events for sockets monitoring.
    */
   struct mhd_DaemonEventsExternal extr;
 };
 
 
 /**
  * The required actions for the daemon
  */
 struct mhd_DaemonEventActionRequired
 {
   /**
    * If 'true' connection resuming is required.
    * TODO: implement resuming
    * TODO: add initialisation
    */
   bool resume;
 };
 
 
 /**
  * The data for events monitoring
  */
 struct mhd_DaemonEventMonitoringData
 {
   /**
    * Sockets polling type used by the daemon.
    */
   enum mhd_IntPollType poll_type;
 
   /**
    * Type-specific events monitoring data
    */
   union mhd_DaemonEventMonitoringTypeSpecificData data;
 
   /**
    * The required actions for the daemon.
    * If daemon has internal thread, this should be changed only inside
    * the daemon's thread.
    */
   struct mhd_DaemonEventActionRequired act_req;
 
   /**
    * When set to 'true' the listen socket has new incoming connection(s).
    */
   bool accept_pending;
 
   /**
    * The list of the daemon's connections that need processing
    */
   mhd_DLNKDL_LIST (MHD_Connection,proc_ready);
 
 };
 
 
 /**
  * The type of the socket
  */
 enum MHD_FIXED_ENUM_ mhd_SocketType
 {
   /**
    * The socket type is some non-IP type.
    */
   mhd_SOCKET_TYPE_NON_IP = -2
   ,
   /**
    * The socket type is UNIX (LOCAL)
    */
   mhd_SOCKET_TYPE_UNIX = -1
   ,
   /**
    * The socket is unknown yet. It can be IP or non-IP.
    */
   mhd_SOCKET_TYPE_UNKNOWN = 0
   ,
   /**
    * The socket is definitely IP.
    */
   mhd_SOCKET_TYPE_IP = 1
 };
 
 /**
  * Listen socket data
  */
 struct mhd_ListenSocket
 {
   /**
    * The listening socket
    */
   MHD_Socket fd;
   /**
    * Set to 'true' when unrecoverable error is detected on the listen socket.
    * If set to 'true', but @a fd is not #MHD_INVALID_SOCKET then "broken" state
    * has not yet processed by MHD.
    */
   bool is_broken;
   /**
    * The type of the listening socket @a fd
    */
   enum mhd_SocketType type;
   /**
    * 'true' if @a fd is non-blocking
    */
   bool non_block;
   /**
    * The port number for @a fd
    *
    * Zero if unknown and for non-IP socket.
    */
   uint_least16_t port;
 };
 
 /**
  * Configured settings for the daemon's network data
  */
 struct mhd_DaemonNetworkSettings
 {
 #ifdef MHD_SOCKETS_KIND_POSIX
   /**
    * The maximum number for the network FDs.
    * The valid FD number must be less then @a max_fd_num.
    */
   MHD_Socket max_fd_num;
 #else
   int dummy; /* mute compiler warning */
 #endif
 };
 
 /**
  * The daemon network/sockets data
  *
  * This structure holds mostly static information -- typically initialised once
  * when the daemon starts, and possibly updated once later (e.g., if the
  * listening socket fails or is closed).
  *
  * It does NOT contain any operational states.
  */
 struct mhd_DaemonNetwork
 {
   /**
    * The listening socket
    */
   struct mhd_ListenSocket listen;
 
 #ifdef MHD_SUPPORT_EPOLL
   /**
    * The epoll FD.
    * Set to '-1' when epoll is not used.
    */
   int epoll_fd;
 #endif
   /**
    * Configured settings for the daemon's network data
    */
   struct mhd_DaemonNetworkSettings cfg;
 };
 
 #ifdef MHD_SUPPORT_AUTH_DIGEST
 
 /**
  * Digest Auth nonce data
  */
 struct mhd_DaemonAuthDigestNonceData
 {
   /**
    * The nonce value in the binary form, excluding validity tail
    */
   uint8_t nonce[mhd_AUTH_DIGEST_NONCE_RAND_BIN_SIZE];
 
   /**
    * The nonce validity time
    */
   uint_fast32_t valid_time;
 
   /**
    * The largest last received 'nc' value.
    * This 'nc' value has been already used by the client.
    */
   uint_fast32_t max_recvd_nc;
 
   /**
    * Bitmask over the previous 64 nc values (down to to nc-64).
    * Used to allow out-of-order 'nc'.
    * If bit in the bitmask is set to one, then this 'nc' value was already used
    * by the client.
    */
   uint_fast64_t nmask;
 };
 
 /**
  * Digest Auth daemon configuration data
  */
 struct mhd_DaemonAuthDigestCfg
 {
   /**
    * The number of elements in the nonces array
    */
   size_t nonces_num;
 
   /**
    * The nonce validity time (in seconds)
    */
   unsigned int nonce_tmout;
 
   /**
    * The default maximum value of nc
    */
   uint_fast32_t def_max_nc;
 };
 
 /**
  * The Digest Auth daemon's data
  */
 struct mhd_DaemonAuthDigestData
 {
   /**
    * The entropy data used for Digests generation
    */
   struct mhd_Buffer entropy;
 
   /**
    * The array of generated nonce and related nc
    */
   struct mhd_DaemonAuthDigestNonceData *nonces;
 
   /**
    * Number of nonces has been generated.
    * Used as addition for the nonce source data to ensure unique nonce value.
    * TODO: remove and directly use random generator for nonce generation.
    */
   struct mhd_AtomicCounter num_gen_nonces;
 
 #ifdef MHD_SUPPORT_THREADS
   /**
    * The mutex to change or access the @a nonces data
    */
   mhd_mutex nonces_lock;
 #endif
 
   /**
    * Digest Auth daemon configuration data
    */
   struct mhd_DaemonAuthDigestCfg cfg;
 };
 
 #endif /* MHD_SUPPORT_AUTH_DIGEST */
 
 #ifdef MHD_SUPPORT_THREADS
 
 /**
  * The type of the daemon
  */
 enum MHD_FIXED_ENUM_ mhd_DaemonType
 {
   /**
    * A single daemon, performing all the work.
    *
    * This daemon may have a optional single thread, managed by MHD.
    */
   mhd_DAEMON_TYPE_SINGLE
 #ifndef NDEBUG
     = 1
 #endif
 #ifdef MHD_SUPPORT_THREADS
   ,
   /**
    * A master daemon, only controlling worker daemons.
    *
    * This daemon never handle any network activity directly.
    */
   mhd_DAEMON_TYPE_MASTER_CONTROL_ONLY
   ,
   /**
    * A daemon with single internal thread for listening and multiple threads
    * handling connections with the clients, one thread per connection.
    */
   mhd_DAEMON_TYPE_LISTEN_ONLY
   ,
   /**
    * A worker daemon, performing the same work as a single daemon, but
    * controlled by master daemon.
    *
    * This type of daemon always have single internal tread and never exposed
    * to application directly.
    */
   mhd_DAEMON_TYPE_WORKER
 #endif /* MHD_SUPPORT_THREADS */
 };
 
 /**
  * Check whether the daemon type is allowed to have internal thread with
  * direct control
  */
 #define mhd_D_TYPE_IS_VALID(t) \
         ((mhd_DAEMON_TYPE_SINGLE <= (t)) && (mhd_DAEMON_TYPE_WORKER >= (t)))
 
 /**
  * Check whether the daemon type must not be exposed to the application
  */
 #define mhd_D_TYPE_IS_INTERNAL_ONLY(t) \
         (mhd_DAEMON_TYPE_WORKER == (t))
 
 /**
  * Check whether the daemon type is allowed to process the network data
  */
 #define mhd_D_TYPE_HAS_EVENTS_PROCESSING(t) \
         (mhd_DAEMON_TYPE_MASTER_CONTROL_ONLY != (t))
 
 /**
  * Check whether the daemon type must not be exposed to the application
  */
 #define mhd_D_TYPE_HAS_WORKERS(t) \
         (mhd_DAEMON_TYPE_MASTER_CONTROL_ONLY == (t))
 
 /**
  * Check whether the daemon type has master (controlling) daemon
  */
 #define mhd_D_TYPE_HAS_MASTER_DAEMON(t) \
         (mhd_DAEMON_TYPE_WORKER == (t))
 
 /**
  * Check whether the daemon is listening only (with connection data
  * processed in separate threads)
  */
 #define mhd_D_TYPE_IS_LISTEN_ONLY(t) \
         (mhd_DAEMON_TYPE_LISTEN_ONLY == (t))
 
 #else  /* ! MHD_SUPPORT_THREADS */
 
 /**
  * Check whether the daemon type is allowed to have internal thread with
  * direct control
  */
 #define mhd_D_TYPE_IS_VALID(t) (! 0)
 
 /**
  * Check whether the daemon type must not be exposed to the application
  */
 #define mhd_D_TYPE_IS_INTERNAL_ONLY(t) (0)
 
 /**
  * Check whether the daemon type is allowed to process the network data
  */
 #define mhd_D_TYPE_HAS_EVENTS_PROCESSING(t) (! 0)
 
 /**
  * Check whether the daemon type must not be exposed to the application
  */
 #define mhd_D_TYPE_HAS_WORKERS(t) (0)
 
 /**
  * Check whether the daemon type has master (controlling) daemon
  */
 #define mhd_D_TYPE_HAS_MASTER_DAEMON(t)  (0)
 
 /**
  * Check whether the daemon is listening only (with connection data
  * processed in separate threads)
  */
 #define mhd_D_TYPE_IS_LISTEN_ONLY(t)    (0)
 
 #endif /* ! MHD_SUPPORT_THREADS */
 
 #ifdef MHD_SUPPORT_THREADS
 
 /**
  * Workers pool data
  */
 struct mhd_DaemonWorkerPoolData
 {
   /**
    * Array of worker daemons
    */
   struct MHD_Daemon *workers;
 
   /**
    * The number of workers in the @a workers array
    */
   unsigned int num;
 };
 
 /**
  * Hierarchy data for the daemon
  */
 union mhd_DaemonHierarchyData
 {
   /**
    * The pointer to the master daemon
    * Only for #mhd_DAEMON_TYPE_WORKER daemons.
    */
   struct MHD_Daemon *master;
 
   /**
    * Workers pool data.
    * Only for #mhd_DAEMON_TYPE_MASTER_CONTROL_ONLY daemons.
    */
   struct mhd_DaemonWorkerPoolData pool;
 };
 
 /**
  * Configured settings for threading
  */
 struct mhd_DaemonThreadingDataSettings
 {
   /**
    * The size of the stack.
    * Zero to use system's defaults.
    */
   size_t stack_size;
 };
 
 /**
  * Threading and Inter-Thread Communication data
  */
 struct mhd_DaemonThreadingData
 {
   /**
    * The type of this daemon
    */
   enum mhd_DaemonType d_type;
 
   /**
    * Inter-Thread Communication channel.
    * Used to trigger processing of the command or the data provided or updated
    * by the application.
    */
   struct mhd_itc itc;
 
   /**
    * 'True' if stop has been requested.
    * The daemon thread should stop all connections and then close.
    */
   volatile bool stop_requested;
 
   /**
    * The handle of the daemon's thread (if managed by the daemon)
    */
   mhd_thread_handle_ID tid;
 
   /**
    * The hierarchy data for the daemon.
    * Used only when @a d_type is #mhd_DAEMON_TYPE_MASTER_CONTROL_ONLY or
    * #mhd_DAEMON_TYPE_WORKER.
    */
   union mhd_DaemonHierarchyData hier;
 
   /**
    * Configured settings for threading
    */
   struct mhd_DaemonThreadingDataSettings cfg;
 };
 
 #endif /* MHD_SUPPORT_THREADS */
 
 /**
  * Configured settings for the daemon's connections
  */
 struct mhd_DaemonConnectionsSettings
 {
   /**
    * The maximum number of connections handled by the daemon
    */
   unsigned int count_limit;
 
   /**
    * The maximum number of connections per any IP handled by the daemon
    */
   unsigned int per_ip_limit;
 
   /**
    * Connection's default timeout value (in milliseconds)
    */
   uint_fast64_t timeout_ms;
 
   /**
    * Connection's memory pool size
    */
   size_t mem_pool_size;
 
   /**
    * Memory pool zeroing mode
    */
   enum mhd_MemPoolZeroing mem_pool_zeroing;
 };
 
 #ifdef MHD_SUPPORT_UPGRADE
 
 /**
  * The data for HTTP-Upgraded connections
  */
 struct mhd_DaemonConnectionsUpgraded
 {
   /**
    * The list of HTTP-Upgraded connection closed by application and
    * queued for cleanup
    */
   mhd_DLNKDL_LIST (MHD_Connection,upgr_cleanup);
 
 #ifdef MHD_SUPPORT_THREADS
   /**
    * The mutex to change or check the @a upgr_cleanup list values
    */
   mhd_mutex ucu_lock;
 #endif
 };
 
 #endif /* MHD_SUPPORT_UPGRADE */
 
 /**
  * Connections handling data
  */
 struct mhd_DaemonConnections
 {
 
   /**
    * The list of all daemon's connections.
    * All connection are listed here, expect connection in @a to_clean list.
    */
   mhd_DLNKDL_LIST (MHD_Connection,all_conn);
 
   /**
    * The list of connections sorted by last activity
    */
   mhd_DLNKDL_LIST (MHD_Connection,def_timeout);
 
   /**
    * The list of connections with custom timeouts
    */
   mhd_DLNKDL_LIST (MHD_Connection,cust_timeout);
 
   /**
    * The current number of connections handled by the daemon
    */
   unsigned int count;
 
   /**
    * If set to 'true' then no new connection is allowed.
    * New connection may be blocked because of various system limits, when
    * additional connection would fail anyway. This flag should be cleared
    * when any already processing connection closed.
    * Can be checked from other threads
    */
   volatile bool block_new;
 
   /**
    * Configured settings for the daemon's connections
    */
   struct mhd_DaemonConnectionsSettings cfg;
 
 #ifdef MHD_SUPPORT_UPGRADE
   /**
    * The data for HTTP-Upgraded connections
    */
   struct mhd_DaemonConnectionsUpgraded upgr;
 #endif /* MHD_SUPPORT_UPGRADE */
 };
 
 /**
  * Early URI callback
  */
 struct mhd_DaemonRequestUriCB
 {
   /**
    * The callback
    */
   MHD_EarlyUriLogCallback cb;
   /**
    * The callback closure
    */
   void *cls;
 };
 
 /**
  * Shared large buffer data
  */
 struct mhd_DaemonLargeBuffer
 {
   /**
    * The amount of memory left allowed to be allocated for the large buffer
    */
   size_t space_left;
 
 #ifdef MHD_SUPPORT_THREADS
   /**
    * The mutex to change or check the @a space_left value
    */
   mhd_mutex lock;
 #endif
 };
 
 #ifdef MHD_SUPPORT_HTTP2
 
 /**
  * Generic settings for HTTP layer communication handling.
  *
  * These settings do not include specific settings for requests processing.
  */
 struct mhd_DaemonHttpSettings
 {
   /**
    * 'true' if HTTP/1.x communication is allowed
    */
   bool http1x;
   /**
    * 'true' if HTTP/2 communication is allowed
    */
   bool http2;
 };
 
 #endif /* MHD_SUPPORT_HTTP2 */
 
 /**
  * Settings for requests processing
  */
 struct mhd_DaemonRequestProcessingSettings
 {
   /**
    * Request callback.
    * The main request processing callback.
    */
   MHD_RequestCallback cb;
 
   /**
    * The closure for @a req_cb
    */
   void *cb_cls;
 
   /**
    * Protocol strictness enforced by MHD on clients.
    */
   enum MHD_ProtocolStrictLevel strictness;
 
 #ifdef MHD_SUPPORT_COOKIES
   /**
    * Disable automatic cookies parsing
    */
   bool disable_cookies;
 #endif
 
   /**
    * Early URI callback
    */
   struct mhd_DaemonRequestUriCB uri_cb; // TODO: set from settings
 
   /**
    * Shared large buffer data
    */
   struct mhd_DaemonLargeBuffer large_buf; // TODO: set from settings
 
   /**
    * Suppress "Date:" header in responses
    */
   bool suppress_date;
 };
 
 
 /**
  * Get whether bare LF in HTTP header and other protocol elements
  * should be treated as the line termination depending on the configured
  * strictness level.
  * RFC 9112, section 2.2
  */
 #define mhd_ALLOW_BARE_LF_AS_CRLF(strictness) (0 >= strictness)
 
 
 #ifndef NDEBUG
 /**
  * Various debugging data
  */
 struct mhd_daemon_debug
 {
   bool net_inited;
   bool net_deinited;
   bool tls_inited;
   bool events_allocated;
   unsigned int num_events_elements;
   bool events_fully_inited;
   bool thread_pool_inited;
   bool threading_inited;
   bool connections_inited;
   bool avoid_accept4;
   size_t initial_lbuf_size;
 };
 #endif /* NDEBUG */
 
 
 struct MHD_Daemon
 {
   /* General data */
 
   /**
    * The daemon state
    */
   enum mhd_DaemonState state;
 
   /**
    * The daemon work mode (private version)
    */
   enum mhd_WorkModeIntType wmode_int;
 
   /* Events/sockets monitoring/polling data */
 
   /**
    * The data for events monitoring
    */
   struct mhd_DaemonEventMonitoringData events;
 
   /* Network/sockets data */
 
   /**
    * The daemon network/sockets data
    *
    * This structure holds mostly static information -- typically initialised
    * once when the daemon starts, and possibly updated once later (e.g., if the
    * listening socket fails or is closed).
    *
    * It does NOT contain any operational states.
    */
   struct mhd_DaemonNetwork net;
 
 #ifdef MHD_SUPPORT_AUTH_DIGEST
   /**
    * The Digest Auth daemon's data
    */
   struct mhd_DaemonAuthDigestData auth_dg;
 #endif /* MHD_SUPPORT_AUTH_DIGEST */
 
 #ifdef MHD_SUPPORT_HTTPS
   /**
    * The pointer to the daemon TLS data.
    * If set to non-NULL then HTTPS protocol is used, if set to NULL then
    * plain HTTP protocol used.
    */
   struct mhd_TlsDaemonData *tls;
 #endif
 
 #ifdef MHD_SUPPORT_THREADS
   /* Threading data */
 
   /**
    * The daemon threading and Inter-Thread Communication data
    */
   struct mhd_DaemonThreadingData threading;
 #endif
 
   /* Connections handling */
 
   /**
    * The connections handling data
    */
   struct mhd_DaemonConnections conns;
 
 
   /* HTTP communication layer */
 #ifdef MHD_SUPPORT_HTTP2
   /**
    * Generic settings for HTTP layer communication handling.
    *
    * These settings do not include specific settings for requests processing.
    */
   struct mhd_DaemonHttpSettings http_cfg;
 #endif /* MHD_SUPPORT_HTTP2 */
 
 
   /* Request processing data */
 
   /**
    * Settings for requests processing
    */
   struct mhd_DaemonRequestProcessingSettings req_cfg;
 
   /* Other data */
 
   /**
    * Daemon logging parameters
    */
   struct MHD_DaemonOptionValueLog log_params;
 
 
   /* Temporal data */
 
   /**
    * User settings, before applied to the daemon itself
    */
   struct DaemonOptions *settings;
 
 #ifndef NDEBUG
   /* Debug data */
 
   struct mhd_daemon_debug dbg;
 #endif
 };
 
 
 #ifdef MHD_SOCKETS_KIND_POSIX
 /**
  * Checks whether @a fd socket number fits limitations for the @a d_ptr daemon
  */
 #  define mhd_FD_FITS_DAEMON(d_ptr,fd) \
         ((MHD_INVALID_SOCKET == d_ptr->net.cfg.max_fd_num) || \
          (d_ptr->net.cfg.max_fd_num > fd))
 #else
 #  define mhd_FD_FITS_DAEMON(d_ptr,fd) (! 0)
 #endif
 
 #ifdef MHD_SUPPORT_EPOLL
 #  define mhd_D_IS_USING_EPOLL(d) \
         (mhd_POLL_TYPE_EPOLL == ((d)->events.poll_type))
 #else
 #  define mhd_D_IS_USING_EPOLL(d) (0)
 #endif
 
 /**
  * Check whether the daemon has edge-triggered sockets polling
  */
 #define mhd_D_HAS_EDGE_TRIGG(d) \
         ((mhd_WM_INT_EXTERNAL_EVENTS_EDGE == (d)->wmode_int) || \
          mhd_D_IS_USING_EPOLL (d))
 
 #ifdef MHD_SUPPORT_THREADS
 #  define mhd_D_HAS_THREADS(d) mhd_WM_INT_HAS_THREADS ((d)->wmode_int)
 #else
 #  define mhd_D_HAS_THREADS(d) (0)
 #endif
 
 #ifdef MHD_SUPPORT_THREADS
 #  define mhd_D_HAS_THR_PER_CONN(d) \
         (mhd_WM_INT_INTERNAL_EVENTS_THREAD_PER_CONNECTION == \
          ((d)->wmode_int))
 #else
 #  define mhd_D_HAS_THR_PER_CONN(d) (0)
 #endif
 
 #ifdef MHD_SUPPORT_THREADS
 #  define mhd_D_HAS_STOP_REQ(d)         (d->threading.stop_requested)
 #else
 #  define mhd_D_HAS_STOP_REQ(d)         (0)
 #endif
 
 #define mhd_D_HAS_WORKERS(d) mhd_D_TYPE_HAS_WORKERS ((d)->threading.d_type)
 
 #define mhd_D_HAS_MASTER(d) mhd_D_TYPE_HAS_MASTER_DAEMON ((d)->threading.d_type)
 
 #define mhd_D_IS_INTERNAL_ONLY(d) \
         mhd_D_TYPE_IS_INTERNAL_ONLY ((d)->threading.d_type)
 
 #define mhd_D_IS_USING_EDGE_TRIG(d) \
         (mhd_D_IS_USING_EPOLL (d) || \
          (mhd_WM_INT_EXTERNAL_EVENTS_EDGE ==((d)->wmode_int)))
 
 #ifdef MHD_SUPPORT_HTTPS
 /**
  * Returns non-zero if daemon has TLS enabled or zero otherwise
  */
 #  define mhd_D_HAS_TLS(d) (((d)->tls) ? (! 0) : (0))
 #else
 /**
  * Returns non-zero if daemon has TLS enabled or zero otherwise
  */
 #  define mhd_D_HAS_TLS(d) (0)
 #endif
 
 /*
  * Check whether the daemon support Digest Auth
  */
 #ifdef MHD_SUPPORT_AUTH_DIGEST
 #  define mhd_D_HAS_AUTH_DIGEST(d) (NULL != (d)->auth_dg.nonces)
 #else
 #  define mhd_D_HAS_AUTH_DIGEST(d) (! ! 0)
 #endif
 
 #ifdef MHD_SUPPORT_HTTP2
 #  define mhd_D_IS_HTTP1_ENABLED(d)     (d->http_cfg.http1x)
 #  define mhd_D_IS_HTTP2_ENABLED(d)     (d->http_cfg.http2)
 #else  /* ! MHD_SUPPORT_HTTP2 */
 #  define mhd_D_IS_HTTP1_ENABLED(d)     (! 0)
 #  define mhd_D_IS_HTTP2_ENABLED(d)     (! ! 0)
 #endif /* ! MHD_SUPPORT_HTTP2 */
 
 
 #endif /* ! MHD_DAEMON_H */