/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#include <sys/types.h>
#include <sys/atomic.h>
#include <sys/pattr.h>
#include <netinet/in.h>
#include <netinet/ip6.h>
#include <inet/common.h>
#include <inet/ip.h>
#include <inet/ip6.h>
#include <ipp/dscpmk/dscpmk_impl.h>

/* Module to mark the ToS/DS field for a given packet */

/* Debug level */
int dscpmk_debug = 0;

/*
 * Given a packet, this routine marks the ToS or DSCP for IPv4 and IPv6 resp.
 * using the configured dscp_map.
 * Note that this module does not change the ECN bits.
 */
int
dscpmk_process(mblk_t **mpp, dscpmk_data_t *dscpmk_data, ip_proc_t proc)
{
        ipha_t *ipha;
        ip6_t *ip6_hdr;
        boolean_t is_v4;
        uint8_t dscp, new_dscp;
        mblk_t *mp;

        ASSERT((mpp != NULL) && (*mpp != NULL));
        mp = *mpp;

        /*
         * The action module will receive an M_DATA or an M_CTL followed
         * by an M_DATA. In the latter case skip the M_CTL.
         */
        if (mp->b_datap->db_type != M_DATA) {
                if ((mp->b_cont != NULL) &&
                    (mp->b_cont->b_datap->db_type == M_DATA)) {
                        mp = mp->b_cont;
                } else {
                        dscpmk0dbg(("dscpmk_process: no data\n"));
                        atomic_inc_64(&dscpmk_data->epackets);
                        return (EINVAL);
                }
        }

        /* Pull-up needed? */
        if ((mp->b_wptr - mp->b_rptr) < IP_SIMPLE_HDR_LENGTH) {
                if (!pullupmsg(mp, IP_SIMPLE_HDR_LENGTH)) {
                        dscpmk0dbg(("dscpmk_process: pullup failed\n"));
                        atomic_inc_64(&dscpmk_data->epackets);
                        return (EINVAL);
                }
        }
        ipha = (ipha_t *)mp->b_rptr;

        /* Update global stats */
        atomic_inc_64(&dscpmk_data->npackets);

        /*
         * This should only be called for outgoing packets. For inbound packets
         * proceed with the next action.
         */
        if ((proc == IPP_LOCAL_IN) || (proc == IPP_FWD_IN)) {
                dscpmk2dbg(("dscpmk_process: cannot mark incoming packets\n"));
                atomic_inc_64(&dscpmk_data->ipackets);
                return (0);
        }

        /* Figure out the ToS or the Traffic Class from the message */
        if (IPH_HDR_VERSION(ipha) == IPV4_VERSION) {
                dscp = ipha->ipha_type_of_service;
                is_v4 = B_TRUE;
        } else {
                ip6_hdr = (ip6_t *)mp->b_rptr;
                dscp = __IPV6_TCLASS_FROM_FLOW(ip6_hdr->ip6_vcf);
                is_v4 = B_FALSE;
        }

        /*
         * Select the new dscp from the dscp_map after ignoring the
         * ECN/CU from dscp (hence dscp >> 2). new_dscp will be the
         * 6-bit DSCP value.
         */
        new_dscp = dscpmk_data->dscp_map[dscp >> 2];

        /* Update stats for this new_dscp */
        atomic_inc_64(&dscpmk_data->dscp_stats[new_dscp].npackets);

        /*
         * if new_dscp is same as the original, update stats and
         * return.
         */
        if (new_dscp == (dscp >> 2)) {
                atomic_inc_64(&dscpmk_data->unchanged);
                return (0);
        }

        /* Get back the ECN/CU value from the original dscp */
        new_dscp = (new_dscp << 2) | (dscp & 0x3);

        atomic_inc_64(&dscpmk_data->changed);
        /*
         * IPv4 : ToS structure -- RFC 791
         *
         *        0   1   2   3   4   5   6   7
         *      +---+---+---+---+---+---+---+---+
         *      | IP Precd  | D | T | R | 0 | 0 |
         *      |           |   |   |   |   |   |
         *      +---+---+---+---+---+---+---+---+
         *
         * For Backward Compatability the diff serv DSCP will be mapped
         * to the 3-bits Precedence field. DTR is not supported. Thus,
         * the following Class Seletor CodePoints are reserved from this
         * purpose : xxx000; where x is 0 or 1 (note the last 2 bits are
         * 00) -- see RFC 2474.
         */

        if (is_v4) {
                ipha->ipha_type_of_service = new_dscp;
                /*
                 * If the hardware supports checksumming, we don't need
                 * to do anything.
                 */
                if (!(mp->b_datap->db_struioun.cksum.flags &
                    HCK_IPV4_HDRCKSUM)) {
                        ipha->ipha_hdr_checksum = 0;
                        ipha->ipha_hdr_checksum = ip_csum_hdr(ipha);
                }
        } else {

        /*
         * IPv6 : DSCP field structure is as given -- RFC 2474
         *
         *        0   1   2   3   4   5   6   7
         *      +---+---+---+---+---+---+---+---+
         *      |       DSCP            | CU    |
         *      |                       |       |
         *      +---+---+---+---+---+---+---+---+
         *
         * CU -- Currently Unused
         *
         * the 32 bit vcf consists of version (4 bits), Traffic class (8 bits)
         * and flow id (20 bits). Need to take care of Big/Little-Endianess.
         */
#ifdef _BIG_ENDIAN
                ip6_hdr->ip6_vcf = (ip6_hdr->ip6_vcf & TCLASS_MASK) |
                    (new_dscp << 20);
#else
                ip6_hdr->ip6_vcf = (ip6_hdr->ip6_vcf & TCLASS_MASK) |
                    ((new_dscp >> 4) | ((new_dscp << 12) & 0xF000));
#endif
        }

        return (0);
}