/*
 * ng_bpf.c
 *
 * Copyright (c) 1999 Whistle Communications, Inc.
 * All rights reserved.
 * 
 * Subject to the following obligations and disclaimer of warranty, use and
 * redistribution of this software, in source or object code forms, with or
 * without modifications are expressly permitted by Whistle Communications;
 * provided, however, that:
 * 1. Any and all reproductions of the source or object code must include the
 *    copyright notice above and the following disclaimer of warranties; and
 * 2. No rights are granted, in any manner or form, to use Whistle
 *    Communications, Inc. trademarks, including the mark "WHISTLE
 *    COMMUNICATIONS" on advertising, endorsements, or otherwise except as
 *    such appears in the above copyright notice or in the software.
 * 
 * THIS SOFTWARE IS BEING PROVIDED BY WHISTLE COMMUNICATIONS "AS IS", AND
 * TO THE MAXIMUM EXTENT PERMITTED BY LAW, WHISTLE COMMUNICATIONS MAKES NO
 * REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING THIS SOFTWARE,
 * INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT.
 * WHISTLE COMMUNICATIONS DOES NOT WARRANT, GUARANBPF, OR MAKE ANY
 * REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS OF THE USE OF THIS
 * SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, RELIABILITY OR OTHERWISE.
 * IN NO EVENT SHALL WHISTLE COMMUNICATIONS BE LIABLE FOR ANY DAMAGES
 * RESULTING FROM OR ARISING OUT OF ANY USE OF THIS SOFTWARE, INCLUDING
 * WITHOUT LIMITATION, ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
 * PUNITIVE, OR CONSEQUENTIAL DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES, LOSS OF USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER 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 WHISTLE COMMUNICATIONS IS ADVISED OF THE POSSIBILITY
 * OF SUCH DAMAGE.
 *
 * Author: Archie Cobbs <archie@freebsd.org>
 *
 * $FreeBSD: src/sys/netgraph/ng_bpf.c,v 1.2.4.4 2002/07/02 23:44:02 archie Exp $
 * $Whistle: ng_bpf.c,v 1.3 1999/12/03 20:30:23 archie Exp $
 */

/*
 * BPF NETGRAPH NODE TYPE
 *
 * This node type accepts any number of hook connections.  With each hook
 * is associated a bpf(4) filter program, and two hook names (each possibly
 * the empty string).  Incoming packets are compared against the filter;
 * matching packets are delivered out the first named hook (or dropped if
 * the empty string), and non-matching packets are delivered out the second
 * named hook (or dropped if the empty string).
 *
 * Each hook also keeps statistics about how many packets have matched, etc.
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/errno.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>

#include <net/bpf.h>

#include <netgraph/ng_message.h>
#include <netgraph/netgraph.h>
#include <netgraph/ng_parse.h>
#include "ng_bpf.h"

#define ERROUT(x)       do { error = (x); goto done; } while (0)

/* Per hook private info */
struct ng_bpf_hookinfo {
        node_p                  node;
        hook_p                  hook;
        struct ng_bpf_hookprog  *prog;
        struct ng_bpf_hookstat  stats;
};
typedef struct ng_bpf_hookinfo *hinfo_p;

/* Netgraph methods */
static ng_constructor_t ng_bpf_constructor;
static ng_rcvmsg_t      ng_bpf_rcvmsg;
static ng_shutdown_t    ng_bpf_rmnode;
static ng_newhook_t     ng_bpf_newhook;
static ng_rcvdata_t     ng_bpf_rcvdata;
static ng_disconnect_t  ng_bpf_disconnect;

/* Internal helper functions */
static int      ng_bpf_setprog(hook_p hook, const struct ng_bpf_hookprog *hp);

/* Parse type for one struct bfp_insn */
static const struct ng_parse_struct_field ng_bpf_insn_type_fields[] = {
        { "code",       &ng_parse_hint16_type   },
        { "jt",         &ng_parse_uint8_type    },
        { "jf",         &ng_parse_uint8_type    },
        { "k",          &ng_parse_uint32_type   },
        { NULL }
};
static const struct ng_parse_type ng_bpf_insn_type = {
        &ng_parse_struct_type,
        &ng_bpf_insn_type_fields
};

/* Parse type for the field 'bpf_prog' in struct ng_bpf_hookprog */
static int
ng_bpf_hookprogary_getLength(const struct ng_parse_type *type,
        const u_char *start, const u_char *buf)
{
        const struct ng_bpf_hookprog *hp;

        hp = (const struct ng_bpf_hookprog *)
            (buf - __offsetof(struct ng_bpf_hookprog, bpf_prog));
        return hp->bpf_prog_len;
}

static const struct ng_parse_array_info ng_bpf_hookprogary_info = {
        &ng_bpf_insn_type,
        &ng_bpf_hookprogary_getLength,
        NULL
};
static const struct ng_parse_type ng_bpf_hookprogary_type = {
        &ng_parse_array_type,
        &ng_bpf_hookprogary_info
};

/* Parse type for struct ng_bpf_hookprog */
static const struct ng_parse_struct_field ng_bpf_hookprog_type_fields[]
        = NG_BPF_HOOKPROG_TYPE_INFO(&ng_bpf_hookprogary_type);
static const struct ng_parse_type ng_bpf_hookprog_type = {
        &ng_parse_struct_type,
        &ng_bpf_hookprog_type_fields
};

/* Parse type for struct ng_bpf_hookstat */
static const struct ng_parse_struct_field ng_bpf_hookstat_type_fields[]
        = NG_BPF_HOOKSTAT_TYPE_INFO;
static const struct ng_parse_type ng_bpf_hookstat_type = {
        &ng_parse_struct_type,
        &ng_bpf_hookstat_type_fields
};

/* List of commands and how to convert arguments to/from ASCII */
static const struct ng_cmdlist ng_bpf_cmdlist[] = {
        {
          NGM_BPF_COOKIE,
          NGM_BPF_SET_PROGRAM,
          "setprogram",
          &ng_bpf_hookprog_type,
          NULL
        },
        {
          NGM_BPF_COOKIE,
          NGM_BPF_GET_PROGRAM,
          "getprogram",
          &ng_parse_hookbuf_type,
          &ng_bpf_hookprog_type
        },
        {
          NGM_BPF_COOKIE,
          NGM_BPF_GET_STATS,
          "getstats",
          &ng_parse_hookbuf_type,
          &ng_bpf_hookstat_type
        },
        {
          NGM_BPF_COOKIE,
          NGM_BPF_CLR_STATS,
          "clrstats",
          &ng_parse_hookbuf_type,
          NULL
        },
        {
          NGM_BPF_COOKIE,
          NGM_BPF_GETCLR_STATS,
          "getclrstats",
          &ng_parse_hookbuf_type,
          &ng_bpf_hookstat_type
        },
        { 0 }
};

/* Netgraph type descriptor */
static struct ng_type typestruct = {
        NG_VERSION,
        NG_BPF_NODE_TYPE,
        NULL,
        ng_bpf_constructor,
        ng_bpf_rcvmsg,
        ng_bpf_rmnode,
        ng_bpf_newhook,
        NULL,
        NULL,
        ng_bpf_rcvdata,
        ng_bpf_rcvdata,
        ng_bpf_disconnect,
        ng_bpf_cmdlist
};
NETGRAPH_INIT(bpf, &typestruct);

/* Default BPF program for a hook that matches nothing */
static const struct ng_bpf_hookprog ng_bpf_default_prog = {
        { '\0' },               /* to be filled in at hook creation time */
        { '\0' },
        { '\0' },
        1,
        { BPF_STMT(BPF_RET+BPF_K, 0) }
};

/*
 * Node constructor
 *
 * We don't keep any per-node private data
 */
static int
ng_bpf_constructor(node_p *nodep)
{
        int error = 0;

        if ((error = ng_make_node_common(&typestruct, nodep)))
                return (error);
        (*nodep)->private = NULL;
        return (0);
}

/*
 * Add a hook
 */
static int
ng_bpf_newhook(node_p node, hook_p hook, const char *name)
{
        hinfo_p hip;
        int error;

        /* Create hook private structure */
        hip = kmalloc(sizeof(*hip), M_NETGRAPH, M_NOWAIT | M_ZERO);
        if (hip == NULL)
                return (ENOMEM);
        hip->hook = hook;
        hook->private = hip;
        hip->node = node;

        /* Attach the default BPF program */
        if ((error = ng_bpf_setprog(hook, &ng_bpf_default_prog)) != 0) {
                kfree(hip, M_NETGRAPH);
                hook->private = NULL;
                return (error);
        }

        /* Set hook name */
        strncpy(hip->prog->thisHook, name, sizeof(hip->prog->thisHook) - 1);
        hip->prog->thisHook[sizeof(hip->prog->thisHook) - 1] = '\0';
        return (0);
}

/*
 * Receive a control message
 */
static int
ng_bpf_rcvmsg(node_p node, struct ng_mesg *msg, const char *retaddr,
           struct ng_mesg **rptr)
{
        struct ng_mesg *resp = NULL;
        int error = 0;

        switch (msg->header.typecookie) {
        case NGM_BPF_COOKIE:
                switch (msg->header.cmd) {
                case NGM_BPF_SET_PROGRAM:
                    {
                        struct ng_bpf_hookprog *const
                            hp = (struct ng_bpf_hookprog *)msg->data;
                        hook_p hook;

                        /* Sanity check */
                        if (msg->header.arglen < sizeof(*hp)
                            || msg->header.arglen
                              != NG_BPF_HOOKPROG_SIZE(hp->bpf_prog_len))
                                ERROUT(EINVAL);

                        /* Find hook */
                        if ((hook = ng_findhook(node, hp->thisHook)) == NULL)
                                ERROUT(ENOENT);

                        /* Set new program */
                        if ((error = ng_bpf_setprog(hook, hp)) != 0)
                                ERROUT(error);
                        break;
                    }

                case NGM_BPF_GET_PROGRAM:
                    {
                        struct ng_bpf_hookprog *hp;
                        hook_p hook;

                        /* Sanity check */
                        if (msg->header.arglen == 0)
                                ERROUT(EINVAL);
                        msg->data[msg->header.arglen - 1] = '\0';

                        /* Find hook */
                        if ((hook = ng_findhook(node, msg->data)) == NULL)
                                ERROUT(ENOENT);

                        /* Build response */
                        hp = ((hinfo_p)hook->private)->prog;
                        NG_MKRESPONSE(resp, msg,
                            NG_BPF_HOOKPROG_SIZE(hp->bpf_prog_len), M_NOWAIT);
                        if (resp == NULL)
                                ERROUT(ENOMEM);
                        bcopy(hp, resp->data,
                           NG_BPF_HOOKPROG_SIZE(hp->bpf_prog_len));
                        break;
                    }

                case NGM_BPF_GET_STATS:
                case NGM_BPF_CLR_STATS:
                case NGM_BPF_GETCLR_STATS:
                    {
                        struct ng_bpf_hookstat *stats;
                        hook_p hook;

                        /* Sanity check */
                        if (msg->header.arglen == 0)
                                ERROUT(EINVAL);
                        msg->data[msg->header.arglen - 1] = '\0';

                        /* Find hook */
                        if ((hook = ng_findhook(node, msg->data)) == NULL)
                                ERROUT(ENOENT);
                        stats = &((hinfo_p)hook->private)->stats;

                        /* Build response (if desired) */
                        if (msg->header.cmd != NGM_BPF_CLR_STATS) {
                                NG_MKRESPONSE(resp,
                                    msg, sizeof(*stats), M_NOWAIT);
                                if (resp == NULL)
                                        ERROUT(ENOMEM);
                                bcopy(stats, resp->data, sizeof(*stats));
                        }

                        /* Clear stats (if desired) */
                        if (msg->header.cmd != NGM_BPF_GET_STATS)
                                bzero(stats, sizeof(*stats));
                        break;
                    }

                default:
                        error = EINVAL;
                        break;
                }
                break;
        default:
                error = EINVAL;
                break;
        }
        if (rptr)
                *rptr = resp;
        else if (resp)
                kfree(resp, M_NETGRAPH);

done:
        kfree(msg, M_NETGRAPH);
        return (error);
}

/*
 * Receive data on a hook
 *
 * Apply the filter, and then drop or forward packet as appropriate.
 */
static int
ng_bpf_rcvdata(hook_p hook, struct mbuf *m, meta_p meta)
{
        const hinfo_p hip = hook->private;
        int totlen = m->m_pkthdr.len;
        int needfree = 0, error = 0;
        u_char *data, buf[256];
        hinfo_p dhip;
        hook_p dest;
        u_int len;

        /* Update stats on incoming hook */
        hip->stats.recvFrames++;
        hip->stats.recvOctets += totlen;

        /* Need to put packet in contiguous memory for bpf */
        if (m->m_next != NULL) {
                if (totlen > sizeof(buf)) {
                        data = kmalloc(totlen, M_NETGRAPH, M_NOWAIT);
                        if (data == NULL) {
                                NG_FREE_DATA(m, meta);
                                return (ENOMEM);
                        }
                        needfree = 1;
                } else
                        data = buf;
                m_copydata(m, 0, totlen, data);
        } else
                data = mtod(m, u_char *);

        /* Run packet through filter */
        len = bpf_filter(hip->prog->bpf_prog, data, totlen, totlen);
        if (needfree)
                kfree(data, M_NETGRAPH);

        /* See if we got a match and find destination hook */
        if (len > 0) {

                /* Update stats */
                hip->stats.recvMatchFrames++;
                hip->stats.recvMatchOctets += totlen;

                /* Truncate packet length if required by the filter */
                if (len < totlen) {
                        m_adj(m, -(totlen - len));
                        totlen -= len;
                }
                dest = ng_findhook(hip->node, hip->prog->ifMatch);
        } else
                dest = ng_findhook(hip->node, hip->prog->ifNotMatch);
        if (dest == NULL) {
                NG_FREE_DATA(m, meta);
                return (0);
        }

        /* Deliver frame out destination hook */
        dhip = (hinfo_p)dest->private;
        dhip->stats.xmitOctets += totlen;
        dhip->stats.xmitFrames++;
        NG_SEND_DATA(error, dest, m, meta);
        return (error);
}

/*
 * Shutdown processing
 */
static int
ng_bpf_rmnode(node_p node)
{
        node->flags |= NG_INVALID;
        ng_cutlinks(node);
        ng_unname(node);
        ng_unref(node);
        return (0);
}

/*
 * Hook disconnection
 */
static int
ng_bpf_disconnect(hook_p hook)
{
        const hinfo_p hip = hook->private;

        KASSERT(hip != NULL, ("%s: null info", __func__));
        kfree(hip->prog, M_NETGRAPH);
        bzero(hip, sizeof(*hip));
        kfree(hip, M_NETGRAPH);
        hook->private = NULL;                   /* for good measure */
        if (hook->node->numhooks == 0)
                ng_rmnode(hook->node);
        return (0);
}

/************************************************************************
                        HELPER STUFF
 ************************************************************************/

/*
 * Set the BPF program associated with a hook
 */
static int
ng_bpf_setprog(hook_p hook, const struct ng_bpf_hookprog *hp0)
{
        const hinfo_p hip = hook->private;
        struct ng_bpf_hookprog *hp;
        int size;

        /* Check program for validity */
        if (!bpf_validate(hp0->bpf_prog, hp0->bpf_prog_len))
                return (EINVAL);

        /* Make a copy of the program */
        size = NG_BPF_HOOKPROG_SIZE(hp0->bpf_prog_len);
        hp = kmalloc(size, M_NETGRAPH, M_NOWAIT);
        if (hp == NULL)
                return (ENOMEM);
        bcopy(hp0, hp, size);

        /* Free previous program, if any, and assign new one */
        if (hip->prog != NULL)
                kfree(hip->prog, M_NETGRAPH);
        hip->prog = hp;
        return (0);
}