/*
 * Copyright (c) 2002 Mark Santcroos <marks@ripe.net>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * Netgraph "device" node
 *
 * This node presents a /dev/ngd%d device that interfaces to an other 
 * netgraph node.
 *
 * $FreeBSD: src/sys/netgraph/ng_device.c,v 1.1.2.1 2002/08/23 07:15:44 julian Exp $
 *
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/mbuf.h>
#include <sys/uio.h>
#include <sys/queue.h>
#include <sys/malloc.h>
#include <sys/conf.h>
#include <sys/poll.h>

#include <netgraph/ng_message.h>
#include <netgraph/netgraph.h>

#include "ng_device.h"

/* turn this on for verbose messages */
#define NGD_DEBUG

/* Netgraph methods */
static ng_constructor_t ng_device_cons;
static ng_rcvmsg_t      ng_device_rcvmsg;
static ng_newhook_t     ng_device_newhook;
static ng_connect_t     ng_device_connect;
static ng_rcvdata_t     ng_device_rcvdata;
static ng_disconnect_t  ng_device_disconnect;
static int              ng_device_mod_event(module_t mod, int event, void *data);

static int ng_device_init(void);
static int get_free_unit(void);

/* Netgraph type */
static struct ng_type typestruct = {
        NG_VERSION,                     /* version */
        NG_DEVICE_NODE_TYPE,            /* name */
        ng_device_mod_event,            /* modevent */
        ng_device_cons,                 /* constructor */
        ng_device_rcvmsg,               /* receive msg */
        NULL,                           /* shutdown */
        ng_device_newhook,              /* newhook */
        NULL,                           /* findhook */
        ng_device_connect,              /* connect */
        ng_device_rcvdata,              /* receive data */
        ng_device_rcvdata,              /* receive queued data */
        ng_device_disconnect,           /* disconnect */
        NULL
};
NETGRAPH_INIT(device, &typestruct);

/* per hook data */
struct ngd_connection {
        SLIST_ENTRY(ngd_connection) links;

        cdev_t  ngddev;
        struct  ng_hook *active_hook;
        char    *readq;
        int     loc;
        int     unit;
};

/* global data */
struct ngd_softc {
        SLIST_HEAD(, ngd_connection) head;

        node_p node;
        char nodename[NG_NODESIZ];
} ngd_softc;

/* helper definition */
#define         MIN(a, b)       ((a) < (b) ? (a) : (b))

/* the per connection receiving queue maximum */
#define NGD_QUEUE_SIZE (1024*10)

/* Maximum number of NGD devices */
#define MAX_NGD 25              /* should be more than enough for now */

static d_close_t ngdclose;
static d_open_t ngdopen;
static d_read_t ngdread;
static d_write_t ngdwrite;
static d_ioctl_t ngdioctl;
static d_poll_t ngdpoll;

#define NGD_CDEV_MAJOR 20
static struct cdevsw ngd_cdevsw = {
        /* name */      "ngd",
        /* maj */       NGD_CDEV_MAJOR,
        /* flags */     0,
        /* port */      NULL,
        /* clone */     NULL,

        /* open */      ngdopen,
        /* close */     ngdclose,
        /* read */      ngdread,
        /* write */     ngdwrite,
        /* ioctl */     ngdioctl,
        /* poll */      ngdpoll,
        /* mmap */      nommap,
        /* strategy */  nostrategy,
        /* dump */      nodump,
        /* psize */     nopsize
};

/* 
 * this holds all the stuff that should be done at load time 
 */
static int
ng_device_mod_event(module_t mod, int event, void *data)
{
        int error = 0;

#ifdef NGD_DEBUG
        kprintf("%s()\n", __func__);
#endif /* NGD_DEBUG */

        switch (event) {
                case MOD_LOAD:
                        cdevsw_add(&ngd_cdevsw, 0, 0);
                        ng_device_init();
                        break;

                case MOD_UNLOAD:
                        /* XXX do we need to do something specific ? */
                        /* ng_device_breakdown */
                        cdevsw_remove(&ngd_cdevsw, 0, 0);
                        error = EBUSY; /* no unload! */
                        break;

                
                default:
                        error = EOPNOTSUPP;
                        break;
        }

        return(error);
}


static int
ng_device_init(void)
{
        struct ngd_softc *sc = &ngd_softc;
        
#ifdef NGD_DEBUG
        kprintf("%s()\n", __func__);
#endif /* NGD_DEBUG */ 

        SLIST_INIT(&sc->head);

        if (ng_make_node_common(&typestruct, &sc->node) != 0) {
                kprintf("%s(): ng_make_node_common failed\n", __func__);
                return(ENXIO);
        }
        ksprintf(sc->nodename, "%s", NG_DEVICE_NODE_TYPE);
        if (ng_name_node(sc->node, sc->nodename)) {
                NG_NODE_UNREF(sc->node); /* make it go away again */
                kprintf("%s(): ng_name_node failed\n", __func__);
                return(ENXIO);
        }
        NG_NODE_SET_PRIVATE(sc->node, sc);

        return(0);
}

/* 
 * don't allow to be created, only the device can do that 
 */
static int
ng_device_cons(node_p node)
{

#ifdef NGD_DEBUG
        kprintf("%s()\n", __func__);
#endif /* NGD_DEBUG */
        
        return(EINVAL);
}

/*
 * Receive control message. We just  free it.
 */
static int
ng_device_rcvmsg(node_p node, 
        struct ng_mesg *msg, const char *retaddr, struct ng_mesg **rptr)
{
        kfree(msg, M_NETGRAPH);
        return(ENOTTY);
}

static int
get_free_unit(void)
{
        struct ngd_connection *tmp = NULL;
        struct ngd_softc *sc = &ngd_softc;
        int n = 0;
        int unit = -1;

#ifdef NGD_DEBUG
        kprintf("%s()\n", __func__);
#endif /* NGD_DEBUG */

        /* When there is no list yet, the first device unit is always 0. */
        if (SLIST_EMPTY(&sc->head)) {
                unit = 0;
                return(unit);
        }

        /* Just do a brute force loop to find the first free unit that is
         * smaller than MAX_NGD.
         * Set MAX_NGD to a large value, doesn't impact performance.
         */
        for(n = 0;n<MAX_NGD && unit == -1;n++) {
                SLIST_FOREACH(tmp, &sc->head, links) {

                        if(tmp->unit == n) {
                                unit = -1;
                                break;
                        }
                        unit = n;
                }
        }

        return(unit);
}

/*
 * incoming hook
 */
static int
ng_device_newhook(node_p node, hook_p hook, const char *name)
{
        struct ngd_softc *sc = &ngd_softc;
        struct ngd_connection * new_connection = NULL;

#ifdef NGD_DEBUG
        kprintf("%s()\n", __func__);
#endif /* NGD_DEBUG */

        new_connection = kmalloc(sizeof(struct ngd_connection), M_DEVBUF, M_NOWAIT);
        if(new_connection == NULL) {
                kprintf("%s(): ERROR: new_connection == NULL\n", __func__);
                return(-1);
        }

        new_connection->unit = get_free_unit();
        if(new_connection->unit<0) {
                kprintf("%s: No free unit found by get_free_unit(), "
                                "increas MAX_NGD\n", __func__);
                kfree(new_connection, M_DEVBUF);
                return(-1);
        }
        new_connection->ngddev = make_dev(&ngd_cdevsw,
            new_connection->unit, 0, 0, 0600, "ngd%d", new_connection->unit);
        if(new_connection->ngddev == NULL) {
                kprintf("%s(): make_dev failed\n", __func__);
                SLIST_REMOVE(&sc->head, new_connection, ngd_connection, links);
                kfree(new_connection, M_DEVBUF);
                return(-1);
        }

        new_connection->readq =
            kmalloc(sizeof(char)*NGD_QUEUE_SIZE, M_DEVBUF, M_NOWAIT | M_ZERO);
        if(new_connection->readq == NULL) {
                kprintf("%s(): readq malloc failed\n", __func__);
                destroy_dev(new_connection->ngddev);
                SLIST_REMOVE(&sc->head, new_connection, ngd_connection, links);
                kfree(new_connection, M_DEVBUF);
                return(-1);
        }

        /* point to begin of buffer */
        new_connection->loc = 0;
        new_connection->active_hook = hook;

        SLIST_INSERT_HEAD(&sc->head, new_connection, links);

        return(0);
}

/*
 * we gave ok to a new hook
 * now connect
 */
static int
ng_device_connect(hook_p hook)
{

#ifdef NGD_DEBUG
        kprintf("%s()\n", __func__);
#endif /* NGD_DEBUG */

        return(0);
}


/*
 * Receive data from hook
 */
static int
ng_device_rcvdata(hook_p hook, struct mbuf *m, meta_p meta)
{
        struct ngd_softc *sc = &ngd_softc;
        struct ngd_connection * connection = NULL;
        struct ngd_connection * tmp;
        char *buffer;

#ifdef NGD_DEBUG
        kprintf("%s()\n", __func__);
#endif /* NGD_DEBUG */

        SLIST_FOREACH(tmp, &sc->head, links) {
                if(tmp->active_hook == hook) {
                        connection = tmp;
                }
        }
        if(connection == NULL) {
                kprintf("%s(): connection still NULL, no hook found\n", __func__);
                return(-1);
        }

        NG_FREE_META(meta);

        m = m_pullup(m, m->m_len);
        if(m == NULL) {
                kprintf("%s(): ERROR: m_pullup failed\n", __func__);
                return(-1);
        }

        buffer = kmalloc(sizeof(char)*m->m_len, M_DEVBUF, M_NOWAIT | M_ZERO);
        if(buffer == NULL) {
                kprintf("%s(): ERROR: buffer malloc failed\n", __func__);
                return(-1);
        }

        buffer = mtod(m, char *);

        if( (connection->loc+m->m_len) < NGD_QUEUE_SIZE) {
                memcpy(connection->readq+connection->loc, buffer, m->m_len);
                connection->loc += m->m_len;
        } else
                kprintf("%s(): queue full, first read out a bit\n", __func__);

        kfree(buffer, M_DEVBUF);

        return(0);
}

/*
 * Removal of the last link destroys the node
 */
static int
ng_device_disconnect(hook_p hook)
{
        struct ngd_softc *sc = &ngd_softc;
        struct ngd_connection * connection = NULL;
        struct ngd_connection * tmp;

#ifdef NGD_DEBUG
        kprintf("%s()\n", __func__);
#endif /* NGD_DEBUG */

        SLIST_FOREACH(tmp, &sc->head, links) {
                if(tmp->active_hook == hook) {
                        connection = tmp;
                }
        }
        if(connection == NULL) {
                kprintf("%s(): connection still NULL, no hook found\n",
                    __func__);
                return(-1);
        }

        kfree(connection->readq, M_DEVBUF);

        destroy_dev(connection->ngddev);

        SLIST_REMOVE(&sc->head, connection, ngd_connection, links);

        return(0);
}
/*
 * the device is opened 
 */
static int
ngdopen(cdev_t dev, int flag, int mode, struct thread *td)
{

#ifdef NGD_DEBUG
        kprintf("%s()\n", __func__);
#endif /* NGD_DEBUG */

        return(0);
}

/*
 * the device is closed 
 */
static int
ngdclose(cdev_t dev, int flag, int mode, struct thread *td)
{

#ifdef NGD_DEBUG
        kprintf("%s()\n", __func__);
#endif

        return(0);
}


/*
 * process ioctl
 *
 * they are translated into netgraph messages and passed on
 * 
 */
static int
ngdioctl(cdev_t dev, u_long cmd, caddr_t addr, int flag, struct thread *td)
{
        struct ngd_softc *sc = &ngd_softc;
        struct ngd_connection * connection = NULL;
        struct ngd_connection * tmp;
        int error = 0;
        struct ng_mesg *msg;
        struct ngd_param_s * datap;

#ifdef NGD_DEBUG
        kprintf("%s()\n", __func__);
#endif /* NGD_DEBUG */

        SLIST_FOREACH(tmp, &sc->head, links) {
                if(tmp->ngddev == dev) {
                        connection = tmp;
                }
        }
        if(connection == NULL) {
                kprintf("%s(): connection still NULL, no dev found\n",
                    __func__);
                return(-1);
        }

        /* NG_MKMESSAGE(msg, cookie, cmdid, len, how) */
        NG_MKMESSAGE(msg, NGM_DEVICE_COOKIE, cmd, sizeof(struct ngd_param_s), 
                        M_NOWAIT);
        if (msg == NULL) {
                kprintf("%s(): msg == NULL\n", __func__);
                goto nomsg;
        }

        /* pass the ioctl data into the ->data area */
        datap = (struct ngd_param_s *)msg->data;
        datap->p = addr;

        /*ng_send_msg(node_p here, struct ng_mesg *msg,
                    const char *address, struct ng_mesg **resp); */
        error = ng_send_msg(sc->node, msg,
            NG_HOOK_NAME(connection->active_hook), NULL);
        if(error)
                kprintf("%s(): ng_send_msg() error: %d\n", __func__, error);

nomsg:

        return(0);
}


/*
 * This function is called when a read(2) is done to our device.
 * We pass the data available in kernelspace on into userland using
 * uiomove.
 */
static int
ngdread(cdev_t dev, struct uio *uio, int flag)
{
        int ret = 0, amnt;
        char buffer[uio->uio_resid+1];
        struct ngd_softc *sc = &ngd_softc;
        struct ngd_connection * connection = NULL;
        struct ngd_connection * tmp;

#ifdef NGD_DEBUG
        kprintf("%s()\n", __func__);
#endif /* NGD_DEBUG */

        SLIST_FOREACH(tmp, &sc->head, links) {
                if(tmp->ngddev == dev) {
                        connection = tmp;
                }
        }
        if(connection == NULL) {
                kprintf("%s(): connection still NULL, no dev found\n", __func__);
                return(-1);
        }

        while ( ( uio->uio_resid > 0 ) && ( connection->loc > 0 ) ) {
                amnt = MIN(uio->uio_resid, connection->loc);

                memcpy(buffer, connection->readq, amnt);
                memcpy(connection->readq, connection->readq+amnt,
                                connection->loc-amnt);
                connection->loc -= amnt;

                ret = uiomove((caddr_t)buffer, amnt, uio);
                if(ret != 0)
                        goto error;

        }
        return(0);

error:
        kprintf("%s(): uiomove returns error %d\n", __func__, ret);
        /* do error cleanup here */
        return(ret);
}


/* 
 * This function is called when our device is written to.
 * We read the data from userland into our local buffer and pass it on
 * into the remote hook.
 *
 */
static int
ngdwrite(cdev_t dev, struct uio *uio, int flag)
{
        int ret;
        int error = 0;
        struct mbuf *m;
        char buffer[uio->uio_resid];
        int len = uio->uio_resid;
        struct ngd_softc *sc =& ngd_softc;
        struct ngd_connection * connection = NULL;
        struct ngd_connection * tmp;

#ifdef NGD_DEBUG
        kprintf("%s()\n", __func__);
#endif /* NGD_DEBUG */

        SLIST_FOREACH(tmp, &sc->head, links) {
                if(tmp->ngddev == dev) {
                        connection = tmp;
                }
        }

        if(connection == NULL) {
                kprintf("%s(): connection still NULL, no dev found\n", __func__);
                return(-1);
        }

        if (len > 0) {
                if ((ret = uiomove((caddr_t)buffer, len, uio)) != 0)
                        goto error;
        } else
                kprintf("%s(): len <= 0 : supposed to happen?!\n", __func__);

        m = m_devget(buffer, len, 0, NULL);

        NG_SEND_DATA_ONLY(error, connection->active_hook, m);

        return(0);

error:
        /* do error cleanup here */
        kprintf("%s(): uiomove returned err: %d\n", __func__, ret);

        return(ret);
}

/*
 * we are being polled/selected
 * check if there is data available for read
 */
static int
ngdpoll(cdev_t dev, int events, struct thread *td)
{
        int revents = 0;
        struct ngd_softc *sc = &ngd_softc;
        struct ngd_connection * connection = NULL;
        struct ngd_connection * tmp;


        if (events & (POLLIN | POLLRDNORM)) {
                /* get the connection we have to know the loc from */
                SLIST_FOREACH(tmp, &sc->head, links) {
                        if(tmp->ngddev == dev) {
                                connection = tmp;
                        }
                }
                if(connection == NULL) {
                        kprintf("%s(): ERROR: connection still NULL, "
                                "no dev found\n", __func__);
                        return(-1);
                }

                if (connection->loc > 0)
                        revents |= events & (POLLIN | POLLRDNORM);
        }

        return(revents);
}