[user/henk/code/inspircd.git] / include / socketengine.h

/*
 * InspIRCd -- Internet Relay Chat Daemon
 *
 *   Copyright (C) 2013-2016 Attila Molnar <attilamolnar@hush.com>
 *   Copyright (C) 2013-2014 Adam <Adam@anope.org>
 *   Copyright (C) 2012-2013, 2017-2020 Sadie Powell <sadie@witchery.services>
 *   Copyright (C) 2012 Robby <robby@chatbelgie.be>
 *   Copyright (C) 2009 Uli Schlachter <psychon@inspircd.org>
 *   Copyright (C) 2009 Daniel De Graaf <danieldg@inspircd.org>
 *   Copyright (C) 2007-2008, 2017 Robin Burchell <robin+git@viroteck.net>
 *   Copyright (C) 2007-2008, 2010 Craig Edwards <brain@inspircd.org>
 *   Copyright (C) 2007 burlex <burlex@e03df62e-2008-0410-955e-edbf42e46eb7>
 *   Copyright (C) 2007 Dennis Friis <peavey@inspircd.org>
 *
 * This file is part of InspIRCd.  InspIRCd is free software: you can
 * redistribute it and/or modify it under the terms of the GNU General Public
 * License as published by the Free Software Foundation, version 2.
 *
 * This program 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 General Public License for more
 * details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */


#pragma once

#include <vector>
#include <string>
#include <map>
#include "config.h"
#include "socket.h"
#include "base.h"

#ifndef _WIN32
#include <sys/uio.h>
#endif

#ifndef IOV_MAX
#define IOV_MAX 1024
#endif

/**
 * Event mask for SocketEngine events
 */
enum EventMask
{
        /** Do not test this socket for readability
         */
        FD_WANT_NO_READ = 0x1,
        /** Give a read event at all times when reads will not block.
         */
        FD_WANT_POLL_READ = 0x2,
        /** Give a read event when there is new data to read.
         *
         * An event MUST be sent if there is new data to be read, and the most
         * recent read/recv() on this FD returned EAGAIN. An event MAY be sent
         * at any time there is data to be read on the socket.
         */
        FD_WANT_FAST_READ = 0x4,
        /** Give an optional read event when reads begin to unblock
         *
         * This state is useful if you want to leave data in the OS receive
         * queue but not get continuous event notifications about it, because
         * it may not require a system call to transition from FD_WANT_FAST_READ
         */
        FD_WANT_EDGE_READ = 0x8,

        /** Mask for all read events */
        FD_WANT_READ_MASK = 0x0F,

        /** Do not test this socket for writeability
         */
        FD_WANT_NO_WRITE = 0x10,
        /** Give a write event at all times when writes will not block.
         *
         * You probably shouldn't use this state; if it's likely that the write
         * will not block, try it first, then use FD_WANT_FAST_WRITE if it
         * fails. If it's likely to block (or you are using polling-style reads)
         * then use FD_WANT_SINGLE_WRITE.
         */
        FD_WANT_POLL_WRITE = 0x20,
        /** Give a write event when writes don't block any more
         *
         * An event MUST be sent if writes will not block, and the most recent
         * write/send() on this FD returned EAGAIN, or connect() returned
         * EINPROGRESS. An event MAY be sent at any time that writes will not
         * block.
         *
         * Before calling OnEventHandler*(), a socket engine MAY change the state of
         * the FD back to FD_WANT_EDGE_WRITE if it is simpler (for example, if a
         * one-shot notification was registered). If further writes are needed,
         * it is the responsibility of the event handler to change the state to
         * one that will generate the required notifications
         */
        FD_WANT_FAST_WRITE = 0x40,
        /** Give an optional write event on edge-triggered write unblock.
         *
         * This state is useful to avoid system calls when moving to/from
         * FD_WANT_FAST_WRITE when writing data to a mostly-unblocked socket.
         */
        FD_WANT_EDGE_WRITE = 0x80,
        /** Request a one-shot poll-style write notification. The socket will
         * return to the FD_WANT_NO_WRITE state before OnEventHandler*() is called.
         */
        FD_WANT_SINGLE_WRITE = 0x100,

        /** Mask for all write events */
        FD_WANT_WRITE_MASK = 0x1F0,

        /** Add a trial read. During the next DispatchEvents invocation, this
         * will call OnEventHandlerRead() unless reads are known to be
         * blocking.
         */
        FD_ADD_TRIAL_READ  = 0x1000,
        /** Assert that reads are known to block. This cancels FD_ADD_TRIAL_READ.
         * Reset by SE before running OnEventHandlerRead().
         */
        FD_READ_WILL_BLOCK = 0x2000,

        /** Add a trial write. During the next DispatchEvents invocation, this
         * will call OnEventHandlerWrite() unless writes are known to be
         * blocking.
         *
         * This could be used to group several writes together into a single
         * send() syscall, or to ensure that writes are blocking when attempting
         * to use FD_WANT_FAST_WRITE.
         */
        FD_ADD_TRIAL_WRITE = 0x4000,
        /** Assert that writes are known to block. This cancels FD_ADD_TRIAL_WRITE.
         * Reset by SE before running OnEventHandlerWrite().
         */
        FD_WRITE_WILL_BLOCK = 0x8000,

        /** Mask for trial read/trial write */
        FD_TRIAL_NOTE_MASK = 0x5000
};

/** This class is a basic I/O handler class.
 * Any object which wishes to receive basic I/O events
 * from the socketengine must derive from this class and
 * implement the OnEventHandler*() methods. The derived class
 * must then be added to SocketEngine using the method
 * SocketEngine::AddFd(), after which point the derived
 * class will receive events to its OnEventHandler*() methods.
 * The event mask passed to SocketEngine::AddFd() determines
 * what events the EventHandler gets notified about and with
 * what semantics. SocketEngine::ChangeEventMask() can be
 * called to update the event mask later. The only
 * requirement beyond this for an event handler is that it
 * must have a file descriptor. What this file descriptor
 * is actually attached to is completely up to you.
 */
class CoreExport EventHandler : public classbase
{
 private:
        /** Private state maintained by socket engine */
        int event_mask;

        void SetEventMask(int mask) { event_mask = mask; }

 protected:
        /** File descriptor.
         * All events which can be handled must have a file descriptor.  This
         * allows you to add events for sockets, fifo's, pipes, and various
         * other forms of IPC.  Do not change this while the object is
         * registered with the SocketEngine
         */
        int fd;

        /** Swaps the internals of this EventHandler with another one.
         * @param other A EventHandler to swap internals with.
         */
        void SwapInternals(EventHandler& other);

 public:
        /** Get the current file descriptor
         * @return The file descriptor of this handler
         */
        inline int GetFd() const { return fd; }

        /** Checks if this event handler has a fd associated with it. */
        inline bool HasFd() const { return fd >= 0; }

        inline int GetEventMask() const { return event_mask; }

        /** Set a new file descriptor
         * @param FD The new file descriptor. Do not call this method without
         * first deleting the object from the SocketEngine if you have
         * added it to a SocketEngine instance.
         */
        void SetFd(int FD);

        /** Constructor
         */
        EventHandler();

        /** Destructor
         */
        virtual ~EventHandler() {}

        /** Called by the socket engine in case of a read event
         */
        virtual void OnEventHandlerRead() = 0;

        /** Called by the socket engine in case of a write event.
         * The default implementation does nothing.
         */
        virtual void OnEventHandlerWrite();

        /** Called by the socket engine in case of an error event.
         * The default implementation does nothing.
         * @param errornum Error code
         */
        virtual void OnEventHandlerError(int errornum);

        friend class SocketEngine;
};

/** Provides basic file-descriptor-based I/O support.
 * The actual socketengine class presents the
 * same interface on all operating systems, but
 * its private members and internal behaviour
 * should be treated as blackboxed, and vary
 * from system to system and upon the config
 * settings chosen by the server admin.
 */
class CoreExport SocketEngine
{
 public:
        /** Socket engine statistics: count of various events, bandwidth usage
         */
        class Statistics
        {
                mutable size_t indata;
                mutable size_t outdata;
                mutable time_t lastempty;

                /** Reset the byte counters and lastempty if there wasn't a reset in this second.
                 */
                void CheckFlush() const;

         public:
                /** Constructor, initializes member vars except indata and outdata because those are set to 0
                 * in CheckFlush() the first time Update() or GetBandwidth() is called.
                 */
                Statistics() : lastempty(0), TotalEvents(0), ReadEvents(0), WriteEvents(0), ErrorEvents(0) { }

                /** Update counters for network data received.
                 * This should be called after every read-type syscall.
                 * @param len_in Number of bytes received, or -1 for error, as typically
                 * returned by a read-style syscall.
                 */
                void UpdateReadCounters(int len_in);

                /** Update counters for network data sent.
                 * This should be called after every write-type syscall.
                 * @param len_out Number of bytes sent, or -1 for error, as typically
                 * returned by a read-style syscall.
                 */
                void UpdateWriteCounters(int len_out);

                /** Get data transfer statistics.
                 * @param kbitpersec_in Filled with incoming traffic in this second in kbit/s.
                 * @param kbitpersec_out Filled with outgoing traffic in this second in kbit/s.
                 * @param kbitpersec_total Filled with total traffic in this second in kbit/s.
                 */
                void CoreExport GetBandwidth(float& kbitpersec_in, float& kbitpersec_out, float& kbitpersec_total) const;

                unsigned long TotalEvents;
                unsigned long ReadEvents;
                unsigned long WriteEvents;
                unsigned long ErrorEvents;
        };

 private:
        /** Reference table, contains all current handlers
         **/
        static std::vector<EventHandler*> ref;

        /** Current number of descriptors in the engine. */
        static size_t CurrentSetSize;

        /** The maximum number of descriptors in the engine. */
        static size_t MaxSetSize;

        /** List of handlers that want a trial read/write
         */
        static std::set<int> trials;

        /** Socket engine statistics: count of various events, bandwidth usage
         */
        static Statistics stats;

        /** Look up the fd limit using rlimit. */
        static void LookupMaxFds();

        /** Terminates the program when the socket engine fails to initialize. */
        static void InitError();

        static void OnSetEvent(EventHandler* eh, int old_mask, int new_mask);

        /** Add an event handler to the base socket engine. AddFd(EventHandler*, int) should call this.
         */
        static bool AddFdRef(EventHandler* eh);

        static void DelFdRef(EventHandler* eh);

        template <typename T>
        static void ResizeDouble(std::vector<T>& vect)
        {
                if (SocketEngine::CurrentSetSize > vect.size())
                        vect.resize(SocketEngine::CurrentSetSize * 2);
        }

public:
#ifndef _WIN32
        typedef iovec IOVector;
#else
        typedef WindowsIOVec IOVector;
#endif

        /** Constructor.
         * The constructor transparently initializes
         * the socket engine which the ircd is using.
         * Please note that if there is a catastrophic
         * failure (for example, you try and enable
         * epoll on a 2.4 linux kernel) then this
         * function may bail back to the shell.
         * @return void, but it is acceptable for this function to bail back to
         * the shell or operating system on fatal error.
         */
        static void Init();

        /** Destructor.
         * The destructor transparently tidies up
         * any resources used by the socket engine.
         */
        static void Deinit();

        /** Add an EventHandler object to the engine.  Use AddFd to add a file
         * descriptor to the engine and have the socket engine monitor it. You
         * must provide an object derived from EventHandler which implements
         * the required OnEventHandler*() methods.
         * @param eh An event handling object to add
         * @param event_mask The initial event mask for the object
         */
        static bool AddFd(EventHandler* eh, int event_mask);

        /** If you call this function and pass it an
         * event handler, that event handler will
         * receive the next available write event,
         * even if the socket is a readable socket only.
         * Developers should avoid constantly keeping
         * an eventhandler in the writeable state,
         * as this will consume large amounts of
         * CPU time.
         * @param eh The event handler to change
         * @param event_mask The changes to make to the wait state
         */
        static void ChangeEventMask(EventHandler* eh, int event_mask);

        /** Returns the number of file descriptors reported by the system this program may use
         * when it was started.
         * @return If non-zero the number of file descriptors that the system reported that we
         * may use.
         */
        static size_t GetMaxFds() { return MaxSetSize; }

        /** Returns the number of file descriptors being queried
         * @return The set size
         */
        static size_t GetUsedFds() { return CurrentSetSize; }

        /** Delete an event handler from the engine.
         * This function call deletes an EventHandler
         * from the engine, returning true if it succeeded
         * and false if it failed. This does not free the
         * EventHandler pointer using delete, if this is
         * required you must do this yourself.
         * @param eh The event handler object to remove
         */
        static void DelFd(EventHandler* eh);

        /** Returns true if a file descriptor exists in
         * the socket engine's list.
         * @param fd The event handler to look for
         * @return True if this fd has an event handler
         */
        static bool HasFd(int fd);

        /** Returns the EventHandler attached to a specific fd.
         * If the fd isn't in the socketengine, returns NULL.
         * @param fd The event handler to look for
         * @return A pointer to the event handler, or NULL
         */
        static EventHandler* GetRef(int fd);

        /** Waits for events and dispatches them to handlers.  Please note that
         * this doesn't wait long, only a couple of milliseconds. It returns the
         * number of events which occurred during this call.  This method will
         * dispatch events to their handlers by calling their
         * EventHandler::OnEventHandler*() methods.
         * @return The number of events which have occurred.
         */
        static int DispatchEvents();

        /** Dispatch trial reads and writes. This causes the actual socket I/O
         * to happen when writes have been pre-buffered.
         */
        static void DispatchTrialWrites();

        /** Returns true if the file descriptors in the given event handler are
         * within sensible ranges which can be handled by the socket engine.
         */
        static bool BoundsCheckFd(EventHandler* eh);

        /** Abstraction for BSD sockets accept(2).
         * This function should emulate its namesake system call exactly.
         * @param fd This version of the call takes an EventHandler instead of a bare file descriptor.
         * @param addr The client IP address and port
         * @param addrlen The size of the sockaddr parameter.
         * @return This method should return exactly the same values as the system call it emulates.
         */
        static int Accept(EventHandler* fd, sockaddr *addr, socklen_t *addrlen);

        /** Close the underlying fd of an event handler, remove it from the socket engine and set the fd to -1.
         * @param eh The EventHandler to close.
         * @return 0 on success, a negative value on error
         */
        static int Close(EventHandler* eh);

        /** Abstraction for BSD sockets close(2).
         * This function should emulate its namesake system call exactly.
         * This function should emulate its namesake system call exactly.
         * @return This method should return exactly the same values as the system call it emulates.
         */
        static int Close(int fd);

        /** Abstraction for BSD sockets send(2).
         * This function should emulate its namesake system call exactly.
         * @param fd This version of the call takes an EventHandler instead of a bare file descriptor.
         * @param buf The buffer in which the data that is sent is stored.
         * @param len The size of the buffer.
         * @param flags A flag value that controls the sending of the data.
         * @return This method should return exactly the same values as the system call it emulates.
         */
        static int Send(EventHandler* fd, const void *buf, size_t len, int flags);

        /** Abstraction for vector write function writev().
         * This function should emulate its namesake system call exactly.
         * @param fd EventHandler to send data with
         * @param iov Array of IOVectors containing the buffers to send and their lengths in the platform's
         * native format.
         * @param count Number of elements in iov.
         * @return This method should return exactly the same values as the system call it emulates.
         */
        static int WriteV(EventHandler* fd, const IOVector* iov, int count);

#ifdef _WIN32
        /** Abstraction for vector write function writev() that accepts a POSIX format iovec.
         * This function should emulate its namesake system call exactly.
         * @param fd EventHandler to send data with
         * @param iov Array of iovecs containing the buffers to send and their lengths in POSIX format.
         * @param count Number of elements in iov.
         * @return This method should return exactly the same values as the system call it emulates.
         */
        static int WriteV(EventHandler* fd, const iovec* iov, int count);
#endif

        /** Abstraction for BSD sockets recv(2).
         * This function should emulate its namesake system call exactly.
         * @param fd This version of the call takes an EventHandler instead of a bare file descriptor.
         * @param buf The buffer in which the data that is read is stored.
         * @param len The size of the buffer.
         * @param flags A flag value that controls the reception of the data.
         * @return This method should return exactly the same values as the system call it emulates.
         */
        static int Recv(EventHandler* fd, void *buf, size_t len, int flags);

        /** Abstraction for BSD sockets recvfrom(2).
         * This function should emulate its namesake system call exactly.
         * @param fd This version of the call takes an EventHandler instead of a bare file descriptor.
         * @param buf The buffer in which the data that is read is stored.
         * @param len The size of the buffer.
         * @param flags A flag value that controls the reception of the data.
         * @param from The remote IP address and port.
         * @param fromlen The size of the from parameter.
         * @return This method should return exactly the same values as the system call it emulates.
         */
        static int RecvFrom(EventHandler* fd, void *buf, size_t len, int flags, sockaddr *from, socklen_t *fromlen);

        /** Abstraction for BSD sockets sendto(2).
         * This function should emulate its namesake system call exactly.
         * @param fd This version of the call takes an EventHandler instead of a bare file descriptor.
         * @param buf The buffer in which the data that is sent is stored.
         * @param len The size of the buffer.
         * @param flags A flag value that controls the sending of the data.
         * @param address The remote IP address and port.
         * @return This method should return exactly the same values as the system call it emulates.
         */
        static int SendTo(EventHandler* fd, const void* buf, size_t len, int flags, const irc::sockets::sockaddrs& address);

        /** Abstraction for BSD sockets connect(2).
         * This function should emulate its namesake system call exactly.
         * @param fd This version of the call takes an EventHandler instead of a bare file descriptor.
         * @param address The server IP address and port.
         * @return This method should return exactly the same values as the system call it emulates.
         */
        static int Connect(EventHandler* fd, const irc::sockets::sockaddrs& address);

        /** Make a file descriptor blocking.
         * @param fd a file descriptor to set to blocking mode
         * @return 0 on success, -1 on failure, errno is set appropriately.
         */
        static int Blocking(int fd);

        /** Make a file descriptor nonblocking.
         * @param fd A file descriptor to set to nonblocking mode
         * @return 0 on success, -1 on failure, errno is set appropriately.
         */
        static int NonBlocking(int fd);

        /** Abstraction for BSD sockets shutdown(2).
         * This function should emulate its namesake system call exactly.
         * @param fd This version of the call takes an EventHandler instead of a bare file descriptor.
         * @param how What part of the socket to shut down
         * @return This method should return exactly the same values as the system call it emulates.
         */
        static int Shutdown(EventHandler* fd, int how);

        /** Abstraction for BSD sockets shutdown(2).
         * This function should emulate its namesake system call exactly.
         * @return This method should return exactly the same values as the system call it emulates.
         */
        static int Shutdown(int fd, int how);

        /** Abstraction for BSD sockets bind(2).
         * This function should emulate its namesake system call exactly.
         * @return This method should return exactly the same values as the system call it emulates.
         */
        static int Bind(int fd, const irc::sockets::sockaddrs& addr);

        /** Abstraction for BSD sockets listen(2).
         * This function should emulate its namesake system call exactly.
         * @return This method should return exactly the same values as the system call it emulates.
         */
        static int Listen(int sockfd, int backlog);

        /** Set SO_REUSEADDR and SO_LINGER on this file descriptor
         */
        static void SetReuse(int sockfd);

        /** This function is called immediately after fork().
         * Some socket engines (notably kqueue) cannot have their
         * handles inherited by forked processes. This method
         * allows for the socket engine to re-create its handle
         * after the daemon forks as the socket engine is created
         * long BEFORE the daemon forks.
         * @return void, but it is acceptable for this function to bail back to
         * the shell or operating system on fatal error.
         */
        static void RecoverFromFork();

        /** Get data transfer and event statistics
         */
        static const Statistics& GetStats() { return stats; }

        /** Should we ignore the error in errno?
         * Checks EAGAIN and WSAEWOULDBLOCK
         */
        static bool IgnoreError();

        /** Return the last socket related error. strrerror(errno) on *nix
         */
        static std::string LastError();

        /** Returns the error for the given error num, strerror(errnum) on *nix
         */
        static std::string GetError(int errnum);
};

inline bool SocketEngine::IgnoreError()
{
        if ((errno == EAGAIN) || (errno == EWOULDBLOCK))
                return true;

#ifdef _WIN32
        if (WSAGetLastError() == WSAEWOULDBLOCK)
                return true;
#endif

        return false;
}