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

/*       +------------------------------------+
 *       | Inspire Internet Relay Chat Daemon |
 *       +------------------------------------+
 *
 *  InspIRCd: (C) 2002-2009 InspIRCd Development Team
 * See: http://wiki.inspircd.org/Credits
 *
 * This program is free but copyrighted software; see
 *            the file COPYING for details.
 *
 * ---------------------------------------------------
 */

#ifndef __SOCKETENGINE__
#define __SOCKETENGINE__

#include <vector>
#include <string>
#include <map>
#include "inspircd_config.h"
#include "base.h"

/** Types of event an EventHandler may receive.
 * EVENT_READ is a readable file descriptor,
 * and EVENT_WRITE is a writeable file descriptor.
 * EVENT_ERROR can always occur, and indicates
 * a write error or read error on the socket,
 * e.g. EOF condition or broken pipe.
 */
enum EventType
{
        /** Read event */
        EVENT_READ      =       0,
        /** Write event */
        EVENT_WRITE     =       1,
        /** Error event */
        EVENT_ERROR     =       2
};

/**
 * 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 HandleEvent, 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 HandleEvent 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 HandleEvent with EVENT_READ 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 EVENT_READ
         */
        FD_READ_WILL_BLOCK = 0x2000,

        /** Add a trial write. During the next DispatchEvents invocation, this
         * will call HandleEvent with EVENT_WRITE 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 EVENT_WRITE
         */
        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 HandleEvent() method. 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 HandleEvent() method.
 * The derived class should also implement one of Readable()
 * and Writeable(). In the current implementation, only
 * Readable() is used. If this returns true, the socketengine
 * inserts a readable socket. If it is false, the socketengine
 * inserts a writeable socket. The derived class should never
 * change the value this function returns without first
 * deleting the socket from the socket engine. 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;
 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;
 public:
        /** Get the current file descriptor
         * @return The file descriptor of this handler
         */
        inline int GetFd() const { return fd; }

        inline int GetEventMask() const { return event_mask; }

        /** Set a new file desciptor
         * @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() {}

        /** Process an I/O event.
         * You MUST implement this function in your derived
         * class, and it will be called whenever read or write
         * events are received.
         * @param et either one of EVENT_READ for read events,
         * and EVENT_WRITE for write events.
         */
        virtual void HandleEvent(EventType et, int errornum = 0) = 0;

        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. The current
 * version supports select, epoll and kqueue.
 * The configure script will enable a socket engine
 * based upon what OS is detected, and will derive
 * a class from SocketEngine based upon what it finds.
 * The derived classes file will also implement a
 * classfactory, SocketEngineFactory, which will
 * create a derived instance of SocketEngine using
 * polymorphism so that the core and modules do not
 * have to be aware of which SocketEngine derived
 * class they are using.
 */
class CoreExport SocketEngine
{
 protected:
        /** Current number of descriptors in the engine
         */
        int CurrentSetSize;
        /** Reference table, contains all current handlers
         */
        EventHandler** ref;
        /** List of handlers that want a trial read/write
         */
        std::set<int> trials;

        int MAX_DESCRIPTORS;

        size_t indata;
        size_t outdata;
        time_t lastempty;

        void UpdateStats(size_t len_in, size_t len_out);

        virtual void OnSetEvent(EventHandler* eh, int old_mask, int new_mask) = 0;
        void SetEventMask(EventHandler* eh, int value);
public:

        double TotalEvents;
        double ReadEvents;
        double WriteEvents;
        double ErrorEvents;

        /** 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.
         */
        SocketEngine();

        /** Destructor.
         * The destructor transparently tidies up
         * any resources used by the socket engine.
         */
        virtual ~SocketEngine();

        /** 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
         * HandleEvent().
         * @param eh An event handling object to add
         * @param event_mask The initial event mask for the object
         */
        virtual bool AddFd(EventHandler* eh, int event_mask) = 0;

        /** 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
         */
        void ChangeEventMask(EventHandler* eh, int event_mask);

        /** Returns the highest file descriptor you may store in the socket engine
         * @return The maximum fd value
         */
        inline int GetMaxFds() const { return MAX_DESCRIPTORS; }

        /** Returns the number of file descriptors being queried
         * @return The set size
         */
        inline int GetUsedFds() const { 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.
         * Note on forcing deletes. DO NOT DO THIS! This is
         * extremely dangerous and will most likely render the
         * socketengine dead. This was added only for handling
         * very rare cases where broken 3rd party libs destroys
         * the OS socket beyond our control. If you can't explain
         * in minute details why forcing is absolutely necessary
         * then you don't need it. That was a NO!
         * @param eh The event handler object to remove
         * @param force *DANGEROUS* See method description!
         * @return True if the event handler was removed
         */
        virtual bool DelFd(EventHandler* eh, bool force = false) = 0;

        /** 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
         */
        virtual bool HasFd(int fd);

        /** Returns the EventHandler attached to a specific fd.
         * If the fd isnt in the socketengine, returns NULL.
         * @param fd The event handler to look for
         * @return A pointer to the event handler, or NULL
         */
        virtual 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::HandleEvent() methods with the necessary EventType
         * value.
         * @return The number of events which have occured.
         */
        virtual int DispatchEvents() = 0;

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

        /** Returns the socket engines name.  This returns the name of the
         * engine for use in /VERSION responses.
         * @return The socket engine name
         */
        virtual std::string GetName() = 0;

        /** Returns true if the file descriptors in the given event handler are
         * within sensible ranges which can be handled by the socket engine.
         */
        virtual 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.
         * @return This method should return exactly the same values as the system call it emulates.
         */
        int Accept(EventHandler* fd, sockaddr *addr, socklen_t *addrlen);

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

        /** 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.
         */
        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.
         * @return This method should return exactly the same values as the system call it emulates.
         */
        int Send(EventHandler* fd, const void *buf, size_t len, int flags);

        /** 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.
         * @return This method should return exactly the same values as the system call it emulates.
         */
        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.
         * @return This method should return exactly the same values as the system call it emulates.
         */
        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.
         * @return This method should return exactly the same values as the system call it emulates.
         */
        int SendTo(EventHandler* fd, const void *buf, size_t len, int flags, const sockaddr *to, socklen_t tolen);

        /** 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.
         * @return This method should return exactly the same values as the system call it emulates.
         */
        int Connect(EventHandler* fd, const sockaddr *serv_addr, socklen_t addrlen);

        /** 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.
         */
        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.
         */
        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.
         * @return This method should return exactly the same values as the system call it emulates.
         */
        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.
         */
        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.
         */
        int Bind(int fd, const sockaddr *my_addr, socklen_t addrlen);

        /** 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.
         */
        int Listen(int sockfd, int backlog);

        /** Set SO_REUSEADDR and SO_LINGER on this file descriptor
         */
        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.
         */
        virtual void RecoverFromFork();

        /** Get data transfer statistics, kilobits per second in and out and total.
         */
        void GetStats(float &kbitpersec_in, float &kbitpersec_out, float &kbitpersec_total);
};

SocketEngine* CreateSocketEngine();

#endif