/*
 * Copyright (C) 2003-2008 Takahiro Hirofuchi
 *
 * This is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
 * USA.
 */

#include <asm/byteorder.h>
#include <linux/kthread.h>
#include <linux/usb.h>
#include <linux/usb/hcd.h>

#include "usbip_common.h"
#include "stub.h"

static int is_clear_halt_cmd(struct urb *urb)
{
        struct usb_ctrlrequest *req;

        req = (struct usb_ctrlrequest *) urb->setup_packet;

         return (req->bRequest == USB_REQ_CLEAR_FEATURE) &&
                 (req->bRequestType == USB_RECIP_ENDPOINT) &&
                 (req->wValue == USB_ENDPOINT_HALT);
}

static int is_set_interface_cmd(struct urb *urb)
{
        struct usb_ctrlrequest *req;

        req = (struct usb_ctrlrequest *) urb->setup_packet;

        return (req->bRequest == USB_REQ_SET_INTERFACE) &&
                (req->bRequestType == USB_RECIP_INTERFACE);
}

static int is_set_configuration_cmd(struct urb *urb)
{
        struct usb_ctrlrequest *req;

        req = (struct usb_ctrlrequest *) urb->setup_packet;

        return (req->bRequest == USB_REQ_SET_CONFIGURATION) &&
                (req->bRequestType == USB_RECIP_DEVICE);
}

static int is_reset_device_cmd(struct urb *urb)
{
        struct usb_ctrlrequest *req;
        __u16 value;
        __u16 index;

        req = (struct usb_ctrlrequest *) urb->setup_packet;
        value = le16_to_cpu(req->wValue);
        index = le16_to_cpu(req->wIndex);

        if ((req->bRequest == USB_REQ_SET_FEATURE) &&
            (req->bRequestType == USB_RT_PORT) &&
            (value == USB_PORT_FEAT_RESET)) {
                usbip_dbg_stub_rx("reset_device_cmd, port %u\n", index);
                return 1;
        } else
                return 0;
}

static int tweak_clear_halt_cmd(struct urb *urb)
{
        struct usb_ctrlrequest *req;
        int target_endp;
        int target_dir;
        int target_pipe;
        int ret;

        req = (struct usb_ctrlrequest *) urb->setup_packet;

        /*
         * The stalled endpoint is specified in the wIndex value. The endpoint
         * of the urb is the target of this clear_halt request (i.e., control
         * endpoint).
         */
        target_endp = le16_to_cpu(req->wIndex) & 0x000f;

        /* the stalled endpoint direction is IN or OUT?. USB_DIR_IN is 0x80.  */
        target_dir = le16_to_cpu(req->wIndex) & 0x0080;

        if (target_dir)
                target_pipe = usb_rcvctrlpipe(urb->dev, target_endp);
        else
                target_pipe = usb_sndctrlpipe(urb->dev, target_endp);

        ret = usb_clear_halt(urb->dev, target_pipe);
        if (ret < 0)
                dev_err(&urb->dev->dev, "usb_clear_halt error: devnum %d endp "
                        "%d ret %d\n", urb->dev->devnum, target_endp, ret);
        else
                dev_info(&urb->dev->dev, "usb_clear_halt done: devnum %d endp "
                         "%d\n", urb->dev->devnum, target_endp);

        return ret;
}

static int tweak_set_interface_cmd(struct urb *urb)
{
        struct usb_ctrlrequest *req;
        __u16 alternate;
        __u16 interface;
        int ret;

        req = (struct usb_ctrlrequest *) urb->setup_packet;
        alternate = le16_to_cpu(req->wValue);
        interface = le16_to_cpu(req->wIndex);

        usbip_dbg_stub_rx("set_interface: inf %u alt %u\n",
                          interface, alternate);

        ret = usb_set_interface(urb->dev, interface, alternate);
        if (ret < 0)
                dev_err(&urb->dev->dev, "usb_set_interface error: inf %u alt "
                        "%u ret %d\n", interface, alternate, ret);
        else
                dev_info(&urb->dev->dev, "usb_set_interface done: inf %u alt "
                         "%u\n", interface, alternate);

        return ret;
}

static int tweak_set_configuration_cmd(struct urb *urb)
{
        struct usb_ctrlrequest *req;
        __u16 config;

        req = (struct usb_ctrlrequest *) urb->setup_packet;
        config = le16_to_cpu(req->wValue);

        /*
         * I have never seen a multi-config device. Very rare.
         * For most devices, this will be called to choose a default
         * configuration only once in an initialization phase.
         *
         * set_configuration may change a device configuration and its device
         * drivers will be unbound and assigned for a new device configuration.
         * This means this usbip driver will be also unbound when called, then
         * eventually reassigned to the device as far as driver matching
         * condition is kept.
         *
         * Unfortunately, an existing usbip connection will be dropped
         * due to this driver unbinding. So, skip here.
         * A user may need to set a special configuration value before
         * exporting the device.
         */
        dev_info(&urb->dev->dev, "usb_set_configuration %d to %s... skip!\n",
                 config, dev_name(&urb->dev->dev));

        return 0;
}

static int tweak_reset_device_cmd(struct urb *urb)
{
        struct stub_priv *priv = (struct stub_priv *) urb->context;
        struct stub_device *sdev = priv->sdev;

        dev_info(&urb->dev->dev, "usb_queue_reset_device\n");

        /*
         * With the implementation of pre_reset and post_reset the driver no
         * longer unbinds. This allows the use of synchronous reset.
         */

        if (usb_lock_device_for_reset(sdev->udev, sdev->interface) < 0) {
                dev_err(&urb->dev->dev, "could not obtain lock to reset device\n");
                return 0;
        }
        usb_reset_device(sdev->udev);
        usb_unlock_device(sdev->udev);

        return 0;
}

/*
 * clear_halt, set_interface, and set_configuration require special tricks.
 */
static void tweak_special_requests(struct urb *urb)
{
        if (!urb || !urb->setup_packet)
                return;

        if (usb_pipetype(urb->pipe) != PIPE_CONTROL)
                return;

        if (is_clear_halt_cmd(urb))
                /* tweak clear_halt */
                 tweak_clear_halt_cmd(urb);

        else if (is_set_interface_cmd(urb))
                /* tweak set_interface */
                tweak_set_interface_cmd(urb);

        else if (is_set_configuration_cmd(urb))
                /* tweak set_configuration */
                tweak_set_configuration_cmd(urb);

        else if (is_reset_device_cmd(urb))
                tweak_reset_device_cmd(urb);
        else
                usbip_dbg_stub_rx("no need to tweak\n");
}

/*
 * stub_recv_unlink() unlinks the URB by a call to usb_unlink_urb().
 * By unlinking the urb asynchronously, stub_rx can continuously
 * process coming urbs.  Even if the urb is unlinked, its completion
 * handler will be called and stub_tx will send a return pdu.
 *
 * See also comments about unlinking strategy in vhci_hcd.c.
 */
static int stub_recv_cmd_unlink(struct stub_device *sdev,
                                struct usbip_header *pdu)
{
        int ret;
        unsigned long flags;
        struct stub_priv *priv;

        spin_lock_irqsave(&sdev->priv_lock, flags);

        list_for_each_entry(priv, &sdev->priv_init, list) {
                if (priv->seqnum != pdu->u.cmd_unlink.seqnum)
                        continue;

                dev_info(&priv->urb->dev->dev, "unlink urb %p\n",
                         priv->urb);

                /*
                 * This matched urb is not completed yet (i.e., be in
                 * flight in usb hcd hardware/driver). Now we are
                 * cancelling it. The unlinking flag means that we are
                 * now not going to return the normal result pdu of a
                 * submission request, but going to return a result pdu
                 * of the unlink request.
                 */
                priv->unlinking = 1;

                /*
                 * In the case that unlinking flag is on, prev->seqnum
                 * is changed from the seqnum of the cancelling urb to
                 * the seqnum of the unlink request. This will be used
                 * to make the result pdu of the unlink request.
                 */
                priv->seqnum = pdu->base.seqnum;

                spin_unlock_irqrestore(&sdev->priv_lock, flags);

                /*
                 * usb_unlink_urb() is now out of spinlocking to avoid
                 * spinlock recursion since stub_complete() is
                 * sometimes called in this context but not in the
                 * interrupt context.  If stub_complete() is executed
                 * before we call usb_unlink_urb(), usb_unlink_urb()
                 * will return an error value. In this case, stub_tx
                 * will return the result pdu of this unlink request
                 * though submission is completed and actual unlinking
                 * is not executed. OK?
                 */
                /* In the above case, urb->status is not -ECONNRESET,
                 * so a driver in a client host will know the failure
                 * of the unlink request ?
                 */
                ret = usb_unlink_urb(priv->urb);
                if (ret != -EINPROGRESS)
                        dev_err(&priv->urb->dev->dev,
                                "failed to unlink a urb %p, ret %d\n",
                                priv->urb, ret);

                return 0;
        }

        usbip_dbg_stub_rx("seqnum %d is not pending\n",
                          pdu->u.cmd_unlink.seqnum);

        /*
         * The urb of the unlink target is not found in priv_init queue. It was
         * already completed and its results is/was going to be sent by a
         * CMD_RET pdu. In this case, usb_unlink_urb() is not needed. We only
         * return the completeness of this unlink request to vhci_hcd.
         */
        stub_enqueue_ret_unlink(sdev, pdu->base.seqnum, 0);

        spin_unlock_irqrestore(&sdev->priv_lock, flags);

        return 0;
}

static int valid_request(struct stub_device *sdev, struct usbip_header *pdu)
{
        struct usbip_device *ud = &sdev->ud;
        int valid = 0;

        if (pdu->base.devid == sdev->devid) {
                spin_lock_irq(&ud->lock);
                if (ud->status == SDEV_ST_USED) {
                        /* A request is valid. */
                        valid = 1;
                }
                spin_unlock_irq(&ud->lock);
        }

        return valid;
}

static struct stub_priv *stub_priv_alloc(struct stub_device *sdev,
                                         struct usbip_header *pdu)
{
        struct stub_priv *priv;
        struct usbip_device *ud = &sdev->ud;
        unsigned long flags;

        spin_lock_irqsave(&sdev->priv_lock, flags);

        priv = kmem_cache_zalloc(stub_priv_cache, GFP_ATOMIC);
        if (!priv) {
                dev_err(&sdev->interface->dev, "alloc stub_priv\n");
                spin_unlock_irqrestore(&sdev->priv_lock, flags);
                usbip_event_add(ud, SDEV_EVENT_ERROR_MALLOC);
                return NULL;
        }

        priv->seqnum = pdu->base.seqnum;
        priv->sdev = sdev;

        /*
         * After a stub_priv is linked to a list_head,
         * our error handler can free allocated data.
         */
        list_add_tail(&priv->list, &sdev->priv_init);

        spin_unlock_irqrestore(&sdev->priv_lock, flags);

        return priv;
}

static int get_pipe(struct stub_device *sdev, int epnum, int dir)
{
        struct usb_device *udev = sdev->udev;
        struct usb_host_endpoint *ep;
        struct usb_endpoint_descriptor *epd = NULL;

        if (dir == USBIP_DIR_IN)
                ep = udev->ep_in[epnum & 0x7f];
        else
                ep = udev->ep_out[epnum & 0x7f];
        if (!ep) {
                dev_err(&sdev->interface->dev, "no such endpoint?, %d\n",
                        epnum);
                BUG();
        }

        epd = &ep->desc;
        if (usb_endpoint_xfer_control(epd)) {
                if (dir == USBIP_DIR_OUT)
                        return usb_sndctrlpipe(udev, epnum);
                else
                        return usb_rcvctrlpipe(udev, epnum);
        }

        if (usb_endpoint_xfer_bulk(epd)) {
                if (dir == USBIP_DIR_OUT)
                        return usb_sndbulkpipe(udev, epnum);
                else
                        return usb_rcvbulkpipe(udev, epnum);
        }

        if (usb_endpoint_xfer_int(epd)) {
                if (dir == USBIP_DIR_OUT)
                        return usb_sndintpipe(udev, epnum);
                else
                        return usb_rcvintpipe(udev, epnum);
        }

        if (usb_endpoint_xfer_isoc(epd)) {
                if (dir == USBIP_DIR_OUT)
                        return usb_sndisocpipe(udev, epnum);
                else
                        return usb_rcvisocpipe(udev, epnum);
        }

        /* NOT REACHED */
        dev_err(&sdev->interface->dev, "get pipe, epnum %d\n", epnum);
        return 0;
}

static void masking_bogus_flags(struct urb *urb)
{
        int                             xfertype;
        struct usb_device               *dev;
        struct usb_host_endpoint        *ep;
        int                             is_out;
        unsigned int    allowed;

        if (!urb || urb->hcpriv || !urb->complete)
                return;
        dev = urb->dev;
        if ((!dev) || (dev->state < USB_STATE_UNAUTHENTICATED))
                return;

        ep = (usb_pipein(urb->pipe) ? dev->ep_in : dev->ep_out)
                [usb_pipeendpoint(urb->pipe)];
        if (!ep)
                return;

        xfertype = usb_endpoint_type(&ep->desc);
        if (xfertype == USB_ENDPOINT_XFER_CONTROL) {
                struct usb_ctrlrequest *setup =
                        (struct usb_ctrlrequest *) urb->setup_packet;

                if (!setup)
                        return;
                is_out = !(setup->bRequestType & USB_DIR_IN) ||
                        !setup->wLength;
        } else {
                is_out = usb_endpoint_dir_out(&ep->desc);
        }

        /* enforce simple/standard policy */
        allowed = (URB_NO_TRANSFER_DMA_MAP | URB_NO_INTERRUPT |
                   URB_DIR_MASK | URB_FREE_BUFFER);
        switch (xfertype) {
        case USB_ENDPOINT_XFER_BULK:
                if (is_out)
                        allowed |= URB_ZERO_PACKET;
                /* FALLTHROUGH */
        case USB_ENDPOINT_XFER_CONTROL:
                allowed |= URB_NO_FSBR; /* only affects UHCI */
                /* FALLTHROUGH */
        default:                        /* all non-iso endpoints */
                if (!is_out)
                        allowed |= URB_SHORT_NOT_OK;
                break;
        case USB_ENDPOINT_XFER_ISOC:
                allowed |= URB_ISO_ASAP;
                break;
        }
        urb->transfer_flags &= allowed;
}

static void stub_recv_cmd_submit(struct stub_device *sdev,
                                 struct usbip_header *pdu)
{
        int ret;
        struct stub_priv *priv;
        struct usbip_device *ud = &sdev->ud;
        struct usb_device *udev = sdev->udev;
        int pipe = get_pipe(sdev, pdu->base.ep, pdu->base.direction);

        priv = stub_priv_alloc(sdev, pdu);
        if (!priv)
                return;

        /* setup a urb */
        if (usb_pipeisoc(pipe))
                priv->urb = usb_alloc_urb(pdu->u.cmd_submit.number_of_packets,
                                          GFP_KERNEL);
        else
                priv->urb = usb_alloc_urb(0, GFP_KERNEL);

        if (!priv->urb) {
                dev_err(&sdev->interface->dev, "malloc urb\n");
                usbip_event_add(ud, SDEV_EVENT_ERROR_MALLOC);
                return;
        }

        /* allocate urb transfer buffer, if needed */
        if (pdu->u.cmd_submit.transfer_buffer_length > 0) {
                priv->urb->transfer_buffer =
                        kzalloc(pdu->u.cmd_submit.transfer_buffer_length,
                                GFP_KERNEL);
                if (!priv->urb->transfer_buffer) {
                        usbip_event_add(ud, SDEV_EVENT_ERROR_MALLOC);
                        return;
                }
        }

        /* copy urb setup packet */
        priv->urb->setup_packet = kmemdup(&pdu->u.cmd_submit.setup, 8,
                                          GFP_KERNEL);
        if (!priv->urb->setup_packet) {
                dev_err(&sdev->interface->dev, "allocate setup_packet\n");
                usbip_event_add(ud, SDEV_EVENT_ERROR_MALLOC);
                return;
        }

        /* set other members from the base header of pdu */
        priv->urb->context                = (void *) priv;
        priv->urb->dev                    = udev;
        priv->urb->pipe                   = pipe;
        priv->urb->complete               = stub_complete;

        usbip_pack_pdu(pdu, priv->urb, USBIP_CMD_SUBMIT, 0);


        if (usbip_recv_xbuff(ud, priv->urb) < 0)
                return;

        if (usbip_recv_iso(ud, priv->urb) < 0)
                return;

        /* no need to submit an intercepted request, but harmless? */
        tweak_special_requests(priv->urb);

        masking_bogus_flags(priv->urb);
        /* urb is now ready to submit */
        ret = usb_submit_urb(priv->urb, GFP_KERNEL);

        if (ret == 0)
                usbip_dbg_stub_rx("submit urb ok, seqnum %u\n",
                                  pdu->base.seqnum);
        else {
                dev_err(&sdev->interface->dev, "submit_urb error, %d\n", ret);
                usbip_dump_header(pdu);
                usbip_dump_urb(priv->urb);

                /*
                 * Pessimistic.
                 * This connection will be discarded.
                 */
                usbip_event_add(ud, SDEV_EVENT_ERROR_SUBMIT);
        }

        usbip_dbg_stub_rx("Leave\n");
        return;
}

/* recv a pdu */
static void stub_rx_pdu(struct usbip_device *ud)
{
        int ret;
        struct usbip_header pdu;
        struct stub_device *sdev = container_of(ud, struct stub_device, ud);
        struct device *dev = &sdev->interface->dev;

        usbip_dbg_stub_rx("Enter\n");

        memset(&pdu, 0, sizeof(pdu));

        /* receive a pdu header */
        ret = usbip_recv(ud->tcp_socket, &pdu, sizeof(pdu));
        if (ret != sizeof(pdu)) {
                dev_err(dev, "recv a header, %d\n", ret);
                usbip_event_add(ud, SDEV_EVENT_ERROR_TCP);
                return;
        }

        usbip_header_correct_endian(&pdu, 0);

        if (usbip_dbg_flag_stub_rx)
                usbip_dump_header(&pdu);

        if (!valid_request(sdev, &pdu)) {
                dev_err(dev, "recv invalid request\n");
                usbip_event_add(ud, SDEV_EVENT_ERROR_TCP);
                return;
        }

        switch (pdu.base.command) {
        case USBIP_CMD_UNLINK:
                stub_recv_cmd_unlink(sdev, &pdu);
                break;

        case USBIP_CMD_SUBMIT:
                stub_recv_cmd_submit(sdev, &pdu);
                break;

        default:
                /* NOTREACHED */
                dev_err(dev, "unknown pdu\n");
                usbip_event_add(ud, SDEV_EVENT_ERROR_TCP);
                break;
        }
}

int stub_rx_loop(void *data)
{
        struct usbip_device *ud = data;

        while (!kthread_should_stop()) {
                if (usbip_event_happened(ud))
                        break;

                stub_rx_pdu(ud);
        }

        return 0;
}