/*
<:copyright-BRCM:2016:DUAL/GPL:standard

   Broadcom Proprietary and Confidential.(c) 2016 Broadcom
   All Rights Reserved

Unless you and Broadcom execute a separate written software license
agreement governing use of this software, this software is licensed
to you under the terms of the GNU General Public License version 2
(the "GPL"), available at http://www.broadcom.com/licenses/GPLv2.php,
with the following added to such license:

   As a special exception, the copyright holders of this software give
   you permission to link this software with independent modules, and
   to copy and distribute the resulting executable under terms of your
   choice, provided that you also meet, for each linked independent
   module, the terms and conditions of the license of that module.
   An independent module is a module which is not derived from this
   software.  The special exception does not apply to any modifications
   of the software.

Not withstanding the above, under no circumstances may you combine
this software in any way with any other Broadcom software provided
under a license other than the GPL, without Broadcom's express prior
written consent.

:>
 */


#include <sys/types.h>
#include <sys/socket.h>
#include <linux/netlink.h>
#include <poll.h>

#include <bcmos_system.h>
#include <bcmtr_plugin.h>
#include <bcm_config.h>
#include <bcmolt_tr_nl.h>

#define BCMNL_TXPREFIX_LEN      (NLMSG_HDRLEN + sizeof(uint32_t))


/* Buffer list header */
typedef struct bcmtr_nl_buf bcmtr_nl_buf;
struct bcmtr_nl_buf
{
    STAILQ_ENTRY(bcmtr_nl_buf) list;
    uint32_t len; /**< Total Length of buffer */
};

/* Plugin channel structure */
typedef struct bcmtr_nl_channel
{
    int device;         /* Device */
    STAILQ_HEAD(nl_buf_list, bcmtr_nl_buf) buf_list;
    bcmos_sem sem;      /* Semaphore that indicates that new buffer is available */
    bcmos_mutex lock;   /* lock that protects this structure */
} bcmtr_nl_channel;

/* A single NL socket is shared by multiple devices.
 * The following control block is used for socket multiplexing
 */
static struct
{
    int s;                                      /* Netlink socket */
    int users;                                  /* Number of users */
    bcmos_mutex lock;                           /* lock that protects this structure */
    bcmos_task nl_rx_task;                      /* Task that reads from the shared NL socket */
    bcmtr_nl_channel *nlch[BCMTR_MAX_OLTS];     /* Channels */
} bcmtr_nl_common;

/* NL socket RX task handler */
static int bcmtr_nl_rx_task_handler(long data);

/** Open first communication channel */
static bcmos_errno bcmtr_nl_open_first(void)
{
    struct sockaddr_nl sa = {};
    bcmos_task_parm tp = {
        .name = "nl_tx",
        .handler = bcmtr_nl_rx_task_handler,
        .priority = TASK_PRIORITY_TRANSPORT_RX
    };
    int s;
    bcmos_errno err;

    s = socket(AF_NETLINK, SOCK_RAW, BCMTR_NL_FAMILY);
    if (s < 0)
    {
        BCMOS_TRACE_RETURN(BCM_ERR_COMM_FAIL, "Can't create NL socket\n");
    }

    /* Connect to remote */
    sa.nl_pid = 0;
    if (connect(s, (struct sockaddr*)&sa, sizeof(sa)) == -1)
    {
        close(s);
        BCMOS_TRACE_RETURN(BCM_ERR_COMM_FAIL, "Can't connect NL socket. error %d (%s)\n",
            errno, strerror(errno));
    }

    /* Bind local */
    sa.nl_family = AF_NETLINK;
    sa.nl_pid = getpid();
    if (bind(s, (struct sockaddr*)&sa, sizeof(sa) ) == -1)
    {
        close(s);
        BCMOS_TRACE_RETURN(BCM_ERR_COMM_FAIL, "Can't bind NL socket. error %d (%s)\n",
            errno, strerror(errno));
    }

    bcmtr_nl_common.s = s;

    /* Create RX thread */
    err = bcmos_task_create(&bcmtr_nl_common.nl_rx_task, &tp);
    if (err)
    {
        close(s);
        bcmtr_nl_common.s = 0;
        BCMOS_TRACE_RETURN(BCM_ERR_COMM_FAIL, "Can't create NL RX thread. error %d (%s)\n",
            err, bcmos_strerror(err));
    }

    return BCM_ERR_OK;
}

/** Close last communication channel */
static bcmos_errno bcmtr_nl_close_last(void)
{
    close(bcmtr_nl_common.s);
    return bcmos_task_destroy(&bcmtr_nl_common.nl_rx_task);
}

/** Open communication channel */
static bcmos_errno bcmtr_nl_open(int device, bcmtr_plugin_cfg *cfg, bcmtr_plugin_channel *ch)
{
    bcmtr_nl_channel *nlch;
    bcmos_errno err = BCM_ERR_OK;

    if ((unsigned)device >= BCMTR_MAX_OLTS)
        BCMOS_TRACE_RETURN(BCM_ERR_PARM, "Device %d is invalid\n");

    if (bcmtr_nl_common.nlch[device])
        BCMOS_TRACE_RETURN(BCM_ERR_ALREADY, "Channel for device %d is already opened\n");

    nlch = bcmos_calloc(sizeof(*nlch));
    if (!nlch)
    {
        BCMOS_TRACE_RETURN(BCM_ERR_NOMEM, "No memory\n");
    }
    nlch->device = device;
    STAILQ_INIT(&nlch->buf_list);
    err = bcmos_mutex_create(&nlch->lock, 0, "tr_nlch");
    err = err ? err : bcmos_sem_create(&nlch->sem, 0, 0, "tr_nlch");

    /* Tie in with the control block shared by all devices */
    bcmos_mutex_lock(&bcmtr_nl_common.lock);
    if (!bcmtr_nl_common.users)
        err = err ? err : bcmtr_nl_open_first();
    if (err)
    {
        bcmos_mutex_unlock(&bcmtr_nl_common.lock);
        bcmos_free(nlch);
        BCMOS_TRACE_RETURN(err, "Failed to open or bind NL socket\n");
    }
    ++bcmtr_nl_common.users;
    bcmtr_nl_common.nlch[device] = nlch;
    bcmos_mutex_unlock(&bcmtr_nl_common.lock);

    *ch = (bcmtr_plugin_channel)nlch;

    return BCM_ERR_OK;
}

/** Close communication channel */
static bcmos_errno bcmtr_nl_close(bcmtr_plugin_channel ch)
{
    bcmtr_nl_channel *nlch = (bcmtr_nl_channel *)ch;
    bcmtr_nl_buf *nl_buf, *nl_buf_tmp;
    bcmolt_buf buf;
    bcmos_errno err = BCM_ERR_OK;

    bcmos_mutex_lock(&bcmtr_nl_common.lock);
    if (bcmtr_nl_common.nlch[nlch->device] == nlch)
    {
        bcmtr_nl_common.nlch[nlch->device] = NULL;
        --bcmtr_nl_common.users;
        if (bcmtr_nl_common.users)
            err = bcmtr_nl_close_last();
    }
    else
    {
        BCMOS_TRACE_ERR("Unexpected NL channel\n");
        err = BCM_ERR_INTERNAL;
    }
    bcmos_mutex_unlock(&bcmtr_nl_common.lock);
    bcmos_mutex_destroy(&nlch->lock);
    bcmos_sem_destroy(&nlch->sem);
    STAILQ_FOREACH_SAFE(nl_buf, &nlch->buf_list, list, nl_buf_tmp)
    {
        STAILQ_REMOVE_HEAD(&nlch->buf_list, list);
        bcmolt_buf_init(&buf, nl_buf->len, (uint8_t *)nl_buf, BCMTR_BUF_ENDIAN);
        bcmolt_buf_free(&buf);
    }
    bcmos_free(nlch);

    return err;
}

/** Send data */
static bcmos_errno bcmtr_nl_send(bcmtr_plugin_channel ch, bcmolt_subchannel subch, bcmolt_buf *buf,
    bcmtr_send_flags flags)
{
    bcmtr_nl_channel *nlch = (bcmtr_nl_channel *)ch;
    int total_len = bcmolt_buf_get_used(buf);
    struct nlmsghdr *nlmsg_hdr = (struct nlmsghdr *)(long)buf->start;
    struct iovec iov = { buf->start, .iov_len=total_len };
    struct msghdr msg = { .msg_iov = &iov, .msg_iovlen = 1 };
    int rc;

    nlmsg_hdr->nlmsg_len = total_len;
    nlmsg_hdr->nlmsg_pid = getpid();
    buf->start[NLMSG_HDRLEN] = nlch->device;

    rc = sendmsg(bcmtr_nl_common.s, &msg, 0);

    return (rc == total_len) ? BCM_ERR_OK : BCM_ERR_COMM_FAIL;
}

/* NL socket RX task handler */
static int bcmtr_nl_rx_task_handler(long data)
{
    bcmos_task *my_task = bcmos_task_current();
    struct iovec iov;
    struct msghdr msg = { .msg_iov = &iov, .msg_iovlen = 1 };
    uint32_t device;
    bcmolt_buf buf = {};
    bcmtr_nl_buf *nl_buf;
    bcmtr_nl_channel *nlch;
    bcmos_errno err;
    int rc;

    while (!my_task->destroy_request)
    {
        err = bcmolt_buf_alloc(&buf, BCMTR_MAX_MTU_SIZE + BCMNL_TXPREFIX_LEN, BCMTR_BUF_ENDIAN);
        if (err)
        {
            /* We are out of memory, hopefully temporary. Wait and continue */
            bcmos_usleep(1000);
            continue;
        }
        iov.iov_base = buf.start;
        iov.iov_len = buf.len;

        /* Wait for message */
        rc = recvmsg(bcmtr_nl_common.s, &msg, 0);
        if (rc < NLMSG_HDRLEN)
        {
            BCMOS_TRACE_ERR("Fatal error. recvmsg() failed with error %d (%s)\n", errno, strerror(errno));
            break;
        }

        /* Device follows NL header */
        memcpy(&device, buf.start + NLMSG_HDRLEN, sizeof(uint32_t));
        if (device >= BCMTR_MAX_OLTS || !(nlch = bcmtr_nl_common.nlch[device]))
        {
            BCMOS_TRACE_ERR("Got message from unexpected device %u. Ignored\n", device);
            bcmolt_buf_free(&buf);
            continue;
        }

        /* Put message on the channel's queue */
        nl_buf = (bcmtr_nl_buf *)(long)buf.start;
        nl_buf->len = rc;
        bcmos_mutex_lock(&nlch->lock);
        STAILQ_INSERT_TAIL(&nlch->buf_list, nl_buf, list);
        bcmos_mutex_unlock(&nlch->lock);
        bcmos_sem_post(&nlch->sem);

        /* Buffer is in use elsewhere */
        buf.start = buf.curr = NULL;
    }

    bcmolt_buf_free(&buf);
    my_task->destroyed = BCMOS_TRUE;
    return 0;
}

/** Receive data */
static bcmos_errno bcmtr_nl_recv(bcmtr_plugin_channel ch, bcmolt_subchannel *subch, bcmolt_buf *buf)
{
    bcmtr_nl_channel *nlch = (bcmtr_nl_channel *)ch;
    bcmtr_nl_buf *nl_buf;
    bcmos_errno err;

    err = bcmos_sem_wait(&nlch->sem, BCMTR_MSG_TIMEOUT * 1000);
    if (err)
        return err;
    bcmos_mutex_lock(&nlch->lock);
    nl_buf = STAILQ_FIRST(&nlch->buf_list);
    if (!nl_buf)
    {
        bcmos_mutex_unlock(&nlch->lock);
        return BCM_ERR_COMM_FAIL;
    }
    STAILQ_REMOVE_HEAD(&nlch->buf_list, list);
    bcmos_mutex_unlock(&nlch->lock);

    /* Got buffer */
    bcmolt_buf_init(buf, nl_buf->len, (uint8_t *)nl_buf, BCMTR_BUF_ENDIAN);
    buf->curr = buf->start + BCMNL_TXPREFIX_LEN;

    *subch = 0;

    return BCM_ERR_OK;
}

/** Initialize plugin callbacks
 * \param[in,out]       driver Transport plugin driver structure
 * \return error code
 */
bcmos_errno bcmtr_nl_plugin_init(bcmtr_plugin_cfg *cfg, bcmtr_driver *driver)
{
    bcmos_errno err;

    bcmos_printf("Launching with a netlink connection\n");

    driver->open = bcmtr_nl_open;
    driver->close = bcmtr_nl_close;
    driver->recv = bcmtr_nl_recv;
    driver->send = bcmtr_nl_send;
    cfg->headroom = BCMNL_TXPREFIX_LEN;

    err = bcmos_mutex_create(&bcmtr_nl_common.lock, 0, "tr_nl");

    return err;
}