/*
 * Copyright (c) 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017 Nicira, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at:
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <config.h>
#include "tc.h"
#include <errno.h>
#include "netlink-socket.h"
#include "netlink.h"
#include "openvswitch/ofpbuf.h"
#include "openvswitch/vlog.h"

VLOG_DEFINE_THIS_MODULE(tc);

/* Returns tc handle 'major':'minor'. */
unsigned int
tc_make_handle(unsigned int major, unsigned int minor)
{
    return TC_H_MAKE(major << 16, minor);
}

/* Returns the major number from 'handle'. */
unsigned int
tc_get_major(unsigned int handle)
{
    return TC_H_MAJ(handle) >> 16;
}

/* Returns the minor number from 'handle'. */
unsigned int
tc_get_minor(unsigned int handle)
{
    return TC_H_MIN(handle);
}

struct tcmsg *
tc_make_request(int ifindex, int type, unsigned int flags,
                struct ofpbuf *request)
{
    struct tcmsg *tcmsg;

    ofpbuf_init(request, 512);
    nl_msg_put_nlmsghdr(request, sizeof *tcmsg, type, NLM_F_REQUEST | flags);
    tcmsg = ofpbuf_put_zeros(request, sizeof *tcmsg);
    tcmsg->tcm_family = AF_UNSPEC;
    tcmsg->tcm_ifindex = ifindex;
    /* Caller should fill in tcmsg->tcm_handle. */
    /* Caller should fill in tcmsg->tcm_parent. */

    return tcmsg;
}

int
tc_transact(struct ofpbuf *request, struct ofpbuf **replyp)
{
    int error = nl_transact(NETLINK_ROUTE, request, replyp);
    ofpbuf_uninit(request);
    return error;
}

/* Adds or deletes a root ingress qdisc on device with specified ifindex.
 *
 * This function is equivalent to running the following when 'add' is true:
 *     /sbin/tc qdisc add dev <devname> handle ffff: ingress
 *
 * This function is equivalent to running the following when 'add' is false:
 *     /sbin/tc qdisc del dev <devname> handle ffff: ingress
 *
 * Where dev <devname> is the device with specified ifindex name.
 *
 * The configuration and stats may be seen with the following command:
 *     /sbin/tc -s qdisc show dev <devname>
 *
 * Returns 0 if successful, otherwise a positive errno value.
 */
int
tc_add_del_ingress_qdisc(int ifindex, bool add)
{
    struct ofpbuf request;
    struct tcmsg *tcmsg;
    int error;
    int type = add ? RTM_NEWQDISC : RTM_DELQDISC;
    int flags = add ? NLM_F_EXCL | NLM_F_CREATE : 0;

    tcmsg = tc_make_request(ifindex, type, flags, &request);
    tcmsg->tcm_handle = tc_make_handle(0xffff, 0);
    tcmsg->tcm_parent = TC_H_INGRESS;
    nl_msg_put_string(&request, TCA_KIND, "ingress");
    nl_msg_put_unspec(&request, TCA_OPTIONS, NULL, 0);

    error = tc_transact(&request, NULL);
    if (error) {
        /* If we're deleting the qdisc, don't worry about some of the
         * error conditions. */
        if (!add && (error == ENOENT || error == EINVAL)) {
            return 0;
        }
        return error;
    }

    return 0;
}