io.c

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/*
 *   This program 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; either version 2 of the License, or (at
 *   your option) any later version.
 *
 *   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, write to the Free Software
 *   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
 */
 
/**
 * $Id: bc8c2f5e425fadc79767d3409c937329bee576cc $
 * @file rlm_unbound/io.c
 * @brief Provides interface between libunbound and the FreeRADIUS event loop
 *
 * @copyright 2019 The FreeRADIUS server project
 * @copyright 2019 Arran Cudbard-Bell (a.cudbardb@freeradius.org)
 */
RCSID("$Id: bc8c2f5e425fadc79767d3409c937329bee576cc $")
 
#define LOG_PREFIX "unbound"
 
#include <freeradius-devel/server/log.h>
#include <freeradius-devel/util/debug.h>
#include <freeradius-devel/util/syserror.h>
 
#include "io.h"
 
#ifdef HAVE_WDOCUMENTATION
DIAG_OFF(documentation)
#endif
#include <unbound-event.h>
#ifdef HAVE_WDOCUMENTATION
DIAG_ON(documentation)
#endif
 
/** Definition for libunbound's event callback
 *
 * Here because they don't provide one.
 */
typedef void(*unbound_cb_t)(int, short flags, void *uctx);
 
/** Wrapper around event handle for our event loop
 *
 * This stores libunbound specific information for an event in our event loop.
 *
 * Lifetime should be bound to the event base.
 */
typedef struct {
        struct ub_event         base;           //!< Unbound event base, which we populate with
                                                ///< callback functions for adding events for FDs
                                                ///< setting timers etc...
                                                ///< MUST BE LISTED FIRST.
 
        unbound_io_event_base_t *ev_b;          //!< Event base this handle was created for.
 
        fr_timer_t              *timer_ev;      //!< Stores the pointer to the enabled timer for
                                                ///< this event handled.  libunbound uses a single
                                                ///< handle for managing related FD events and
                                                ///< timers, which is weird, but ok...
 
        short                   events;         //!< The events this event handle should receive
                                                ///< when activated.
 
        int                     fd;             //!< File descriptor this event handle relates to.
 
        unbound_cb_t            cb;             //!< The callback we need to call when a specified
                                                ///< event happens.
 
        void                    *uctx;          //!< This is the argument libunbound wants passed to
                                                ///< the callback when it's called.  It usually
                                                ///< contains libunbound's internal connection handled.
                                                ///< We don't have any visibility, it just remains
                                                ///< an opaque blob to us.
 
        bool                    active;         //!< Whether this event is considered active.
} unbound_io_event_t;
 
/** Alter the enabled flags associated with the event
 *
 * Event *MUST* be disabled before these flags are changed.
 */
static void _unbound_io_event_flags_add(struct ub_event *ub_ev, short flags)
{
        unbound_io_event_t      *ev = talloc_get_type_abort(ub_ev, unbound_io_event_t);
        short                   new = ev->events | flags;
 
        DEBUG4("unbound event %p - Adding flags %i (current %i, new %i)", ev, flags, ev->events, new);
 
        fr_assert(!ev->active); /* must not be active */
 
        ev->events = new;
}
 
/** Alter the enabled flags associated with the event
 *
 * Event *MUST* be disabled before these flags are changed.
 */
static void _unbound_io_event_flags_del(struct ub_event *ub_ev, short flags)
{
        unbound_io_event_t      *ev = talloc_get_type_abort(ub_ev, unbound_io_event_t);
        short                   new = ev->events & ~flags;
 
        fr_assert(!ev->active);                 /* must not be active */
 
        DEBUG4("unbound event %p - Removing flags %i (current %i, new %i)", ev, flags, ev->events, new);
 
        ev->events = new;
}
 
/** Change the file descriptor associated with an event
 *
 * Event *MUST* be disabled before changing the fd.
 */
static void _unbound_io_event_fd_set(struct ub_event *ub_ev, int fd)
{
        unbound_io_event_t      *ev = talloc_get_type_abort(ub_ev, unbound_io_event_t);
 
        fr_assert(!ev->active);                 /* must not be active */
 
        if (fd == ev->fd) return;
 
        DEBUG4("unbound event %p - Changed FD from %i to %i", ev, ev->fd, fd);
 
        ev->fd = fd;
}
 
/** Free an event, and, by the magic of talloc, any timers or fd events
 *
 */
static void _unbound_io_event_free(struct ub_event *ub_ev)
{
        unbound_io_event_t      *ev = talloc_get_type_abort(ub_ev, unbound_io_event_t);
 
        DEBUG4("unbound event %p - Freed", ev);
 
        talloc_free(ev);
}
 
/** Timeout fired
 *
 * Unbound uses these timeouts as part of its mechanism to measure rtt from
 * candidate DNS servers, working out which is the fastest to use for any
 * given query.  The timeout happening causes the timeout against the server
 * to be increased for any subsequent queries sent to it.
 */
static void _unbound_io_service_timer_expired(UNUSED fr_timer_list_t *tl, UNUSED fr_time_t now, void *uctx)
{
        unbound_io_event_t      *ev = talloc_get_type_abort(uctx, unbound_io_event_t);
 
        DEBUG4("unbound event %p - Timeout", ev);
 
        ev->cb(-1, UB_EV_TIMEOUT, ev->uctx);    /* Inform libunbound */
}
 
/** Unbound FD became readable
 *
 * Because we don't have the separation between the IO event loop
 * and the event loop processing results, we call ub_process
 * immediately after calling the IO callback.
 */
static void _unbound_io_service_readable(fr_event_list_t *el, int fd, UNUSED int flags, void *uctx)
{
        unbound_io_event_t      *ev = talloc_get_type_abort(uctx, unbound_io_event_t);
 
        fr_assert(ev->active);                  /* must be active */
 
        DEBUG4("unbound event %p - FD %i now readable", ev, fd);
 
        ev->cb(fd, UB_EV_READ, ev->uctx);               /* Inform libunbound */
 
        /*
         *      Remove IO events
         */
        if (!(ev->events & UB_EV_PERSIST)) {
                DEBUG4("unbound event %p - UB_EV_PERSIST not set - Removing events for FD %i", ev, ev->fd);
                if (fr_event_fd_delete(el, ev->fd, FR_EVENT_FILTER_IO) < 0) {
                        PERROR("unbound event %p - De-registration failed for FD %i", ev, ev->fd);
                }
        }
}
 
/** Unbound FD became writable
 *
 */
static void _unbound_io_service_writable(fr_event_list_t *el, int fd, UNUSED int flags, void *uctx)
{
        unbound_io_event_t      *ev = talloc_get_type_abort(uctx, unbound_io_event_t);
 
        fr_assert(ev->active);                  /* must be active */
 
        DEBUG4("unbound event %p - FD %i now writable", ev, fd);
 
        ev->cb(fd, UB_EV_WRITE, ev->uctx);      /* Inform libunbound */
 
        /*
         *      Remove IO events
         */
        if (!(ev->events & UB_EV_PERSIST)) {
                DEBUG4("unbound event %p - UB_EV_PERSIST not set - Removing events for FD %i", ev, ev->fd);
                if (fr_event_fd_delete(el, ev->fd, FR_EVENT_FILTER_IO) < 0) {
                        PERROR("unbound event %p - De-registration failed for FD %i", ev, ev->fd);
                }
        }
}
 
/** Unbound FD errored
 *
 * libunbound doesn't request errors, so tell it a timeout occurred
 *
 * Because we don't have the separation between the IO event loop
 * and the event loop processing results, we call ub_process
 * immediately after calling the IO callback.
 */
static void _unbound_io_service_errored(UNUSED fr_event_list_t *el,
                                        int fd, UNUSED int flags, int fd_errno, void *uctx)
{
        unbound_io_event_t      *ev = talloc_get_type_abort(uctx, unbound_io_event_t);
 
        fr_assert(ev->active);                  /* must be active */
 
        DEBUG4("unbound event %p - FD %i errored: %s", ev, fd, fr_syserror(fd_errno));
 
        /*
         *      Delete the timer as we're telling libunbound
         *      that it fired.  This is imperfect but unbound
         *      doesn't have a callback for receiving errors.
         */
        FR_TIMER_DISARM(ev->timer_ev);
 
        ev->cb(-1, UB_EV_TIMEOUT, ev->uctx);    /* Call libunbound - pretend this is a timeout */
}
 
 
/** Activate FD events and set a timer for a timeout
 *
 */
static int _unbound_io_event_activate(struct ub_event *ub_ev, struct timeval *tv)
{
        unbound_io_event_t      *ev = talloc_get_type_abort(ub_ev, unbound_io_event_t);
 
        fr_assert(!ev->active); /* must not be active */
 
        /*
         *      File descriptor event
         */
        if ((ev->events & UB_EV_READ) && (ev->events & UB_EV_WRITE)) {
                fr_assert(ev->fd >= 0); /* File descriptor must valid */
 
                DEBUG4("unbound event %p - Registered for read+write events on FD %i", ev, ev->fd);
 
                if (fr_event_fd_insert(ev, NULL, ev->ev_b->el, ev->fd,
                                       _unbound_io_service_readable,
                                       _unbound_io_service_writable,
                                       _unbound_io_service_errored,
                                       ev) < 0) {
                        PERROR("unbound event %p - Registration failed for read+write+error events on FD %i",
                               ev, ev->fd);
 
                        return -1;
                }
        } else if (ev->events & UB_EV_READ) {
                fr_assert(ev->fd >= 0); /* File descriptor must valid */
 
                DEBUG4("unbound event %p - Registered for read+error events on FD %i", ev, ev->fd);
 
                if (fr_event_fd_insert(ev, NULL, ev->ev_b->el, ev->fd,
                                       _unbound_io_service_readable,
                                       NULL,
                                       _unbound_io_service_errored,
                                       ev) < 0) {
                        PERROR("unbound event %p - Registration failed for read+error events on FD %i",
                               ev, ev->fd);
 
                        return -1;
                }
        } else if (ev->events & UB_EV_WRITE) {
                fr_assert(ev->fd >= 0); /* File descriptor must valid */
 
                DEBUG4("unbound event %p - Registered for write+error events on FD %i", ev, ev->fd);
 
                if (fr_event_fd_insert(ev, NULL, ev->ev_b->el, ev->fd,
                                       NULL,
                                       _unbound_io_service_writable,
                                       _unbound_io_service_errored,
                                       ev) < 0) {
                        PERROR("unbound event %p - Registration failed for write+error events on FD %i",
                               ev, ev->fd);
 
                        return -1;
                }
        }
 
        /*
         *      Add a timeout event
         */
        if (ev->events & UB_EV_TIMEOUT) {
                fr_time_delta_t timeout = fr_time_delta_from_timeval(tv);
 
                DEBUG4("unbound event %p - Timeout in %pV seconds", ev, fr_box_time_delta(timeout));
 
                if (fr_timer_in(ev, ev->ev_b->el->tl, &ev->timer_ev,
                                timeout, false, _unbound_io_service_timer_expired, ev) < 0) {
                        PERROR("unbound event %p - Failed adding timeout", ev);
 
                        if (ev->events & (UB_EV_READ | UB_EV_WRITE)) {
                                fr_event_fd_delete(ev->ev_b->el, ev->fd, FR_EVENT_FILTER_IO);
                        }
 
                        return -1;
                }
        }
 
        ev->active = true;      /* Event is now active! */
 
        return 0;
}
 
/* Deactivate FD events and disarm the timeout
 *
 */
static int _unbound_io_event_deactivate(struct ub_event *ub_ev)
{
        unbound_io_event_t      *ev = talloc_get_type_abort(ub_ev, unbound_io_event_t);
        int                     ret = 0;
 
        if (!ev->active) return 0;      /* Allow this to be called multiple times */
 
        if (ev->events & (UB_EV_READ | UB_EV_WRITE)) {
                DEBUG4("unbound event %p - De-registering FD %i", ev, ev->fd);
 
                if (fr_event_fd_delete(ev->ev_b->el, ev->fd, FR_EVENT_FILTER_IO) < 0) {
                        PERROR("unbound event %p - De-registration failed for FD %i", ev, ev->fd);
 
                        ret = -1;
                }
        }
 
        if (ev->events & UB_EV_TIMEOUT) {
                DEBUG4("unbound event %p - Disarming timeout", ev);
 
                FR_TIMER_DISARM_RETURN(ev->timer_ev);
        }
 
        ev->active = false;     /* Event is now inactive and can be modified */
 
        return ret;
}
 
/** Modify an existing timeout
 *
 */
static int _unbound_io_timer_modify(struct ub_event *ub_ev, UNUSED struct ub_event_base *ev_b,
                                    void (*cb)(int, short, void*),
                                    void *uctx, struct timeval *tv)
{
        unbound_io_event_t      *ev = talloc_get_type_abort(ub_ev, unbound_io_event_t);
        int                     ret = 0;
        fr_time_delta_t         timeout;
 
        fr_assert(ev->events & UB_EV_TIMEOUT);
 
        if (ev->cb != cb) {
                DEBUG4("unbound event %p - New callback %p (old callback was %p)",
                       ev, cb, ev->cb);
                ev->cb = cb;
        }
        if (ev->uctx != uctx) {
                DEBUG4("unbound event %p - New uctx %p (old uctx was %p)",
                       ev, uctx, ev->uctx);
                ev->uctx = uctx;
        }
        FR_TIMER_DISARM_RETURN(ev->timer_ev);
 
        timeout = fr_time_delta_from_timeval(tv);
 
        DEBUG4("unbound event %p - Timeout in %pV seconds", ev, fr_box_time_delta(timeout));
 
        if (fr_timer_in(ev, ev->ev_b->el->tl, &ev->timer_ev,
                        timeout,
                        false, _unbound_io_service_timer_expired, ev) < 0) {
                PERROR("unbound event %p - Failed adding timeout", ev);
 
                ret = -1;
        }
 
        return ret;
}
 
/** Deactivate a timeout
 *
 */
static int _unbound_io_timer_deactivate(struct ub_event *ub_ev)
{
        unbound_io_event_t      *ev = talloc_get_type_abort(ub_ev, unbound_io_event_t);
 
        fr_assert(ev->events & UB_EV_TIMEOUT);
 
        DEBUG4("unbound event %p - Disarming timeout", ev);
 
        FR_TIMER_DISARM_RETURN(ev->timer_ev);
 
        return 0;
}
 
/** Returns a new libunbound event handle
 *
 * This handle is used by libunbound to interface with the worker's event loop
 */
static struct ub_event *_unbound_io_event_new(struct ub_event_base* base, int fd, short flags,
                                              void (*cb)(int, short, void*), void *uctx)
{
        unbound_io_event_base_t *ev_b = talloc_get_type_abort(base, unbound_io_event_base_t);
        unbound_io_event_t      *ev;
 
        static struct ub_event_vmt      vmt = {
                .add_bits       = _unbound_io_event_flags_add,
                .del_bits       = _unbound_io_event_flags_del,
                .set_fd         = _unbound_io_event_fd_set,
                .free           = _unbound_io_event_free,
                .add            = _unbound_io_event_activate,
                .del            = _unbound_io_event_deactivate,
                .add_timer      = _unbound_io_timer_modify,
                .del_timer      = _unbound_io_timer_deactivate
        };
 
        MEM(ev = talloc_zero(ev_b, unbound_io_event_t));
        ev->base.magic = UB_EVENT_MAGIC;        /* Magic value libunbound requires */
        ev->base.vmt = &vmt;                    /* Callbacks for adding/removing timers/fd events */
        ev->ev_b = ev_b;                        /* Our event base (containing the el ) */
        ev->events = flags;                     /* When this event should fire */
        ev->fd = fd;                            /* File descriptor to register events for */
        ev->cb = cb;                            /* Callback to execute on event */
        ev->uctx = uctx;                        /* Lib unbound's arg to pass to the cb */
        ev->active = false;                     /* Event is not currently active */
 
        DEBUG4("unbound event %p - Allocated - Events %i, FD %i, callback %p, uctx %p", ev, flags, fd, cb, uctx);
 
        return (struct ub_event *)ev;
}
 
static int _event_base_free(unbound_io_event_base_t *ev_b)
{
        if (ev_b->ub) ub_ctx_delete(ev_b->ub);
 
        return 0;
}
 
/** Alloc a new event base, and unbound ctx initialised from that event base
 *
 * The ub_ctx is configured to use the el specified.
 *
 * When the thread ctx is freed, unbound_io_free should be called to gracefully
 * free the ub_ctx, and then the event base structure it depends on.
 *
 * @param[in] ctx       Talloc ctx to allocate even base in.
 * @param[out] ev_b_out Event base.  Free with talloc_free.
 * @param[in] el        To use to run the unbound event loop.
 * @return
 *      - 0 on success.
 *      - -1 on failure.
 */
int unbound_io_init(TALLOC_CTX *ctx, unbound_io_event_base_t **ev_b_out, fr_event_list_t *el)
{
        unbound_io_event_base_t *ev_b;
 
        static struct ub_event_base_vmt vmt = {
                .new_event      = _unbound_io_event_new
        };
 
        /*
         *      Should be manually freed *AFTER* t->ub
         *      is freed.  So must be parented from the NULL
         *      ctx.
         */
        MEM(ev_b = talloc_zero(ctx, unbound_io_event_base_t));
        ev_b->base.magic = UB_EVENT_MAGIC;
        ev_b->base.vmt = &vmt;
        ev_b->el = el;
 
        /*
         *      Create the main ub_ctx using our event base
         *      which specifies how libunbound integrates
         *      with our event loop.
         */
        ev_b->ub = ub_ctx_create_ub_event((struct ub_event_base *)ev_b);
        if (!ev_b->ub) {
                ERROR("Failed creating ub_ctx");
                TALLOC_FREE(ev_b);
                return -1;
        }
        talloc_set_destructor(ev_b, _event_base_free);
 
        *ev_b_out = ev_b;
 
        return 0;
}