/*
 * Copyright (c) 2010 Voltaire Inc.  All rights reserved.
 *
 * This software is available to you under a choice of one of two
 * licenses.  You may choose to be licensed under the terms of the GNU
 * General Public License (GPL) Version 2, available from the file
 * COPYING in the main directory of this source tree, or the
 * OpenIB.org BSD license below:
 *
 *     Redistribution and use in source and binary forms, with or
 *     without modification, are permitted provided that the following
 *     conditions are met:
 *
 *      - Redistributions of source code must retain the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer.
 *
 *      - 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.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#define pr_fmt(fmt) "%s:%s: " fmt, KBUILD_MODNAME, __func__

#include <linux/export.h>
#include <net/netlink.h>
#include <net/net_namespace.h>
#include <net/sock.h>
#include <rdma/rdma_netlink.h>
#include "core_priv.h"

struct ibnl_client {
        struct list_head                list;
        int                             index;
        int                             nops;
        const struct ibnl_client_cbs   *cb_table;
};

static DEFINE_MUTEX(ibnl_mutex);
static struct sock *nls;
static LIST_HEAD(client_list);

int ibnl_chk_listeners(unsigned int group)
{
        if (netlink_has_listeners(nls, group) == 0)
                return -1;
        return 0;
}

int ibnl_add_client(int index, int nops,
                    const struct ibnl_client_cbs cb_table[])
{
        struct ibnl_client *cur;
        struct ibnl_client *nl_client;

        nl_client = kmalloc(sizeof *nl_client, GFP_KERNEL);
        if (!nl_client)
                return -ENOMEM;

        nl_client->index        = index;
        nl_client->nops         = nops;
        nl_client->cb_table     = cb_table;

        mutex_lock(&ibnl_mutex);

        list_for_each_entry(cur, &client_list, list) {
                if (cur->index == index) {
                        pr_warn("Client for %d already exists\n", index);
                        mutex_unlock(&ibnl_mutex);
                        kfree(nl_client);
                        return -EINVAL;
                }
        }

        list_add_tail(&nl_client->list, &client_list);

        mutex_unlock(&ibnl_mutex);

        return 0;
}
EXPORT_SYMBOL(ibnl_add_client);

int ibnl_remove_client(int index)
{
        struct ibnl_client *cur, *next;

        mutex_lock(&ibnl_mutex);
        list_for_each_entry_safe(cur, next, &client_list, list) {
                if (cur->index == index) {
                        list_del(&(cur->list));
                        mutex_unlock(&ibnl_mutex);
                        kfree(cur);
                        return 0;
                }
        }
        pr_warn("Can't remove callback for client idx %d. Not found\n", index);
        mutex_unlock(&ibnl_mutex);

        return -EINVAL;
}
EXPORT_SYMBOL(ibnl_remove_client);

void *ibnl_put_msg(struct sk_buff *skb, struct nlmsghdr **nlh, int seq,
                   int len, int client, int op, int flags)
{
        unsigned char *prev_tail;

        prev_tail = skb_tail_pointer(skb);
        *nlh = nlmsg_put(skb, 0, seq, RDMA_NL_GET_TYPE(client, op),
                         len, flags);
        if (!*nlh)
                goto out_nlmsg_trim;
        (*nlh)->nlmsg_len = skb_tail_pointer(skb) - prev_tail;
        return nlmsg_data(*nlh);

out_nlmsg_trim:
        nlmsg_trim(skb, prev_tail);
        return NULL;
}
EXPORT_SYMBOL(ibnl_put_msg);

int ibnl_put_attr(struct sk_buff *skb, struct nlmsghdr *nlh,
                  int len, void *data, int type)
{
        unsigned char *prev_tail;

        prev_tail = skb_tail_pointer(skb);
        if (nla_put(skb, type, len, data))
                goto nla_put_failure;
        nlh->nlmsg_len += skb_tail_pointer(skb) - prev_tail;
        return 0;

nla_put_failure:
        nlmsg_trim(skb, prev_tail - nlh->nlmsg_len);
        return -EMSGSIZE;
}
EXPORT_SYMBOL(ibnl_put_attr);

static int ibnl_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
                        struct netlink_ext_ack *extack)
{
        struct ibnl_client *client;
        int type = nlh->nlmsg_type;
        int index = RDMA_NL_GET_CLIENT(type);
        unsigned int op = RDMA_NL_GET_OP(type);

        list_for_each_entry(client, &client_list, list) {
                if (client->index == index) {
                        if (op >= client->nops || !client->cb_table[op].dump)
                                return -EINVAL;

                        /*
                         * For response or local service set_timeout request,
                         * there is no need to use netlink_dump_start.
                         */
                        if (!(nlh->nlmsg_flags & NLM_F_REQUEST) ||
                            (index == RDMA_NL_LS &&
                             op == RDMA_NL_LS_OP_SET_TIMEOUT)) {
                                struct netlink_callback cb = {
                                        .skb = skb,
                                        .nlh = nlh,
                                        .dump = client->cb_table[op].dump,
                                        .module = client->cb_table[op].module,
                                };

                                return cb.dump(skb, &cb);
                        }

                        {
                                struct netlink_dump_control c = {
                                        .dump = client->cb_table[op].dump,
                                        .module = client->cb_table[op].module,
                                };
                                return netlink_dump_start(nls, skb, nlh, &c);
                        }
                }
        }

        pr_info("Index %d wasn't found in client list\n", index);
        return -EINVAL;
}

static void ibnl_rcv_reply_skb(struct sk_buff *skb)
{
        struct nlmsghdr *nlh;
        int msglen;

        /*
         * Process responses until there is no more message or the first
         * request. Generally speaking, it is not recommended to mix responses
         * with requests.
         */
        while (skb->len >= nlmsg_total_size(0)) {
                nlh = nlmsg_hdr(skb);

                if (nlh->nlmsg_len < NLMSG_HDRLEN || skb->len < nlh->nlmsg_len)
                        return;

                /* Handle response only */
                if (nlh->nlmsg_flags & NLM_F_REQUEST)
                        return;

                ibnl_rcv_msg(skb, nlh, NULL);

                msglen = NLMSG_ALIGN(nlh->nlmsg_len);
                if (msglen > skb->len)
                        msglen = skb->len;
                skb_pull(skb, msglen);
        }
}

static void ibnl_rcv(struct sk_buff *skb)
{
        mutex_lock(&ibnl_mutex);
        ibnl_rcv_reply_skb(skb);
        netlink_rcv_skb(skb, &ibnl_rcv_msg);
        mutex_unlock(&ibnl_mutex);
}

int ibnl_unicast(struct sk_buff *skb, struct nlmsghdr *nlh,
                        __u32 pid)
{
        int err;

        err = netlink_unicast(nls, skb, pid, 0);
        return (err < 0) ? err : 0;
}
EXPORT_SYMBOL(ibnl_unicast);

int ibnl_multicast(struct sk_buff *skb, struct nlmsghdr *nlh,
                        unsigned int group, gfp_t flags)
{
        return nlmsg_multicast(nls, skb, 0, group, flags);
}
EXPORT_SYMBOL(ibnl_multicast);

int __init ibnl_init(void)
{
        struct netlink_kernel_cfg cfg = {
                .input  = ibnl_rcv,
        };

        nls = netlink_kernel_create(&init_net, NETLINK_RDMA, &cfg);
        if (!nls) {
                pr_warn("Failed to create netlink socket\n");
                return -ENOMEM;
        }

        nls->sk_sndtimeo = 10 * HZ;
        return 0;
}

void ibnl_cleanup(void)
{
        struct ibnl_client *cur, *next;

        mutex_lock(&ibnl_mutex);
        list_for_each_entry_safe(cur, next, &client_list, list) {
                list_del(&(cur->list));
                kfree(cur);
        }
        mutex_unlock(&ibnl_mutex);

        netlink_kernel_release(nls);
}