// SPDX-License-Identifier: GPL-2.0+
/*
 * Copyright (C) 2003-2008 Takahiro Hirofuchi
 * Copyright (C) 2015-2016 Samsung Electronics
 *               Krzysztof Opasiak <k.opasiak@samsung.com>
 */

#include <asm/byteorder.h>
#include <linux/file.h>
#include <linux/fs.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/stat.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <net/sock.h>

#include "usbip_common.h"

#define DRIVER_AUTHOR "Takahiro Hirofuchi <hirofuchi@users.sourceforge.net>"
#define DRIVER_DESC "USB/IP Core"

#ifdef CONFIG_USBIP_DEBUG
unsigned long usbip_debug_flag = 0xffffffff;
#else
unsigned long usbip_debug_flag;
#endif
EXPORT_SYMBOL_GPL(usbip_debug_flag);
module_param(usbip_debug_flag, ulong, S_IRUGO|S_IWUSR);
MODULE_PARM_DESC(usbip_debug_flag, "debug flags (defined in usbip_common.h)");

/* FIXME */
struct device_attribute dev_attr_usbip_debug;
EXPORT_SYMBOL_GPL(dev_attr_usbip_debug);

static ssize_t usbip_debug_show(struct device *dev,
                                struct device_attribute *attr, char *buf)
{
        return sprintf(buf, "%lx\n", usbip_debug_flag);
}

static ssize_t usbip_debug_store(struct device *dev,
                                 struct device_attribute *attr, const char *buf,
                                 size_t count)
{
        if (sscanf(buf, "%lx", &usbip_debug_flag) != 1)
                return -EINVAL;
        return count;
}
DEVICE_ATTR_RW(usbip_debug);

static void usbip_dump_buffer(char *buff, int bufflen)
{
        print_hex_dump(KERN_DEBUG, "usbip-core", DUMP_PREFIX_OFFSET, 16, 4,
                       buff, bufflen, false);
}

static void usbip_dump_pipe(unsigned int p)
{
        unsigned char type = usb_pipetype(p);
        unsigned char ep   = usb_pipeendpoint(p);
        unsigned char dev  = usb_pipedevice(p);
        unsigned char dir  = usb_pipein(p);

        pr_debug("dev(%d) ep(%d) [%s] ", dev, ep, dir ? "IN" : "OUT");

        switch (type) {
        case PIPE_ISOCHRONOUS:
                pr_debug("ISO\n");
                break;
        case PIPE_INTERRUPT:
                pr_debug("INT\n");
                break;
        case PIPE_CONTROL:
                pr_debug("CTRL\n");
                break;
        case PIPE_BULK:
                pr_debug("BULK\n");
                break;
        default:
                pr_debug("ERR\n");
                break;
        }
}

static void usbip_dump_usb_device(struct usb_device *udev)
{
        struct device *dev = &udev->dev;
        int i;

        dev_dbg(dev, "       devnum(%d) devpath(%s) usb speed(%s)",
                udev->devnum, udev->devpath, usb_speed_string(udev->speed));

        pr_debug("tt hub ttport %d\n", udev->ttport);

        dev_dbg(dev, "                    ");
        for (i = 0; i < 16; i++)
                pr_debug(" %2u", i);
        pr_debug("\n");

        dev_dbg(dev, "       toggle0(IN) :");
        for (i = 0; i < 16; i++)
                pr_debug(" %2u", (udev->toggle[0] & (1 << i)) ? 1 : 0);
        pr_debug("\n");

        dev_dbg(dev, "       toggle1(OUT):");
        for (i = 0; i < 16; i++)
                pr_debug(" %2u", (udev->toggle[1] & (1 << i)) ? 1 : 0);
        pr_debug("\n");

        dev_dbg(dev, "       epmaxp_in   :");
        for (i = 0; i < 16; i++) {
                if (udev->ep_in[i])
                        pr_debug(" %2u",
                            le16_to_cpu(udev->ep_in[i]->desc.wMaxPacketSize));
        }
        pr_debug("\n");

        dev_dbg(dev, "       epmaxp_out  :");
        for (i = 0; i < 16; i++) {
                if (udev->ep_out[i])
                        pr_debug(" %2u",
                            le16_to_cpu(udev->ep_out[i]->desc.wMaxPacketSize));
        }
        pr_debug("\n");

        dev_dbg(dev, "parent %s, bus %s\n", dev_name(&udev->parent->dev),
                udev->bus->bus_name);

        dev_dbg(dev, "have_langid %d, string_langid %d\n",
                udev->have_langid, udev->string_langid);

        dev_dbg(dev, "maxchild %d\n", udev->maxchild);
}

static void usbip_dump_request_type(__u8 rt)
{
        switch (rt & USB_RECIP_MASK) {
        case USB_RECIP_DEVICE:
                pr_debug("DEVICE");
                break;
        case USB_RECIP_INTERFACE:
                pr_debug("INTERF");
                break;
        case USB_RECIP_ENDPOINT:
                pr_debug("ENDPOI");
                break;
        case USB_RECIP_OTHER:
                pr_debug("OTHER ");
                break;
        default:
                pr_debug("------");
                break;
        }
}

static void usbip_dump_usb_ctrlrequest(struct usb_ctrlrequest *cmd)
{
        if (!cmd) {
                pr_debug("       : null pointer\n");
                return;
        }

        pr_debug("       ");
        pr_debug("bRequestType(%02X) bRequest(%02X) wValue(%04X) wIndex(%04X) wLength(%04X) ",
                 cmd->bRequestType, cmd->bRequest,
                 cmd->wValue, cmd->wIndex, cmd->wLength);
        pr_debug("\n       ");

        if ((cmd->bRequestType & USB_TYPE_MASK) == USB_TYPE_STANDARD) {
                pr_debug("STANDARD ");
                switch (cmd->bRequest) {
                case USB_REQ_GET_STATUS:
                        pr_debug("GET_STATUS\n");
                        break;
                case USB_REQ_CLEAR_FEATURE:
                        pr_debug("CLEAR_FEAT\n");
                        break;
                case USB_REQ_SET_FEATURE:
                        pr_debug("SET_FEAT\n");
                        break;
                case USB_REQ_SET_ADDRESS:
                        pr_debug("SET_ADDRRS\n");
                        break;
                case USB_REQ_GET_DESCRIPTOR:
                        pr_debug("GET_DESCRI\n");
                        break;
                case USB_REQ_SET_DESCRIPTOR:
                        pr_debug("SET_DESCRI\n");
                        break;
                case USB_REQ_GET_CONFIGURATION:
                        pr_debug("GET_CONFIG\n");
                        break;
                case USB_REQ_SET_CONFIGURATION:
                        pr_debug("SET_CONFIG\n");
                        break;
                case USB_REQ_GET_INTERFACE:
                        pr_debug("GET_INTERF\n");
                        break;
                case USB_REQ_SET_INTERFACE:
                        pr_debug("SET_INTERF\n");
                        break;
                case USB_REQ_SYNCH_FRAME:
                        pr_debug("SYNC_FRAME\n");
                        break;
                default:
                        pr_debug("REQ(%02X)\n", cmd->bRequest);
                        break;
                }
                usbip_dump_request_type(cmd->bRequestType);
        } else if ((cmd->bRequestType & USB_TYPE_MASK) == USB_TYPE_CLASS) {
                pr_debug("CLASS\n");
        } else if ((cmd->bRequestType & USB_TYPE_MASK) == USB_TYPE_VENDOR) {
                pr_debug("VENDOR\n");
        } else if ((cmd->bRequestType & USB_TYPE_MASK) == USB_TYPE_RESERVED) {
                pr_debug("RESERVED\n");
        }
}

void usbip_dump_urb(struct urb *urb)
{
        struct device *dev;

        if (!urb) {
                pr_debug("urb: null pointer!!\n");
                return;
        }

        if (!urb->dev) {
                pr_debug("urb->dev: null pointer!!\n");
                return;
        }

        dev = &urb->dev->dev;

        usbip_dump_usb_device(urb->dev);

        dev_dbg(dev, "   pipe                  :%08x ", urb->pipe);

        usbip_dump_pipe(urb->pipe);

        dev_dbg(dev, "   status                :%d\n", urb->status);
        dev_dbg(dev, "   transfer_flags        :%08X\n", urb->transfer_flags);
        dev_dbg(dev, "   transfer_buffer_length:%d\n",
                                                urb->transfer_buffer_length);
        dev_dbg(dev, "   actual_length         :%d\n", urb->actual_length);

        if (urb->setup_packet && usb_pipetype(urb->pipe) == PIPE_CONTROL)
                usbip_dump_usb_ctrlrequest(
                        (struct usb_ctrlrequest *)urb->setup_packet);

        dev_dbg(dev, "   start_frame           :%d\n", urb->start_frame);
        dev_dbg(dev, "   number_of_packets     :%d\n", urb->number_of_packets);
        dev_dbg(dev, "   interval              :%d\n", urb->interval);
        dev_dbg(dev, "   error_count           :%d\n", urb->error_count);
}
EXPORT_SYMBOL_GPL(usbip_dump_urb);

void usbip_dump_header(struct usbip_header *pdu)
{
        pr_debug("BASE: cmd %u seq %u devid %u dir %u ep %u\n",
                 pdu->base.command,
                 pdu->base.seqnum,
                 pdu->base.devid,
                 pdu->base.direction,
                 pdu->base.ep);

        switch (pdu->base.command) {
        case USBIP_CMD_SUBMIT:
                pr_debug("USBIP_CMD_SUBMIT: x_flags %u x_len %u sf %u #p %d iv %d\n",
                         pdu->u.cmd_submit.transfer_flags,
                         pdu->u.cmd_submit.transfer_buffer_length,
                         pdu->u.cmd_submit.start_frame,
                         pdu->u.cmd_submit.number_of_packets,
                         pdu->u.cmd_submit.interval);
                break;
        case USBIP_CMD_UNLINK:
                pr_debug("USBIP_CMD_UNLINK: seq %u\n",
                         pdu->u.cmd_unlink.seqnum);
                break;
        case USBIP_RET_SUBMIT:
                pr_debug("USBIP_RET_SUBMIT: st %d al %u sf %d #p %d ec %d\n",
                         pdu->u.ret_submit.status,
                         pdu->u.ret_submit.actual_length,
                         pdu->u.ret_submit.start_frame,
                         pdu->u.ret_submit.number_of_packets,
                         pdu->u.ret_submit.error_count);
                break;
        case USBIP_RET_UNLINK:
                pr_debug("USBIP_RET_UNLINK: status %d\n",
                         pdu->u.ret_unlink.status);
                break;
        default:
                /* NOT REACHED */
                pr_err("unknown command\n");
                break;
        }
}
EXPORT_SYMBOL_GPL(usbip_dump_header);

/* Receive data over TCP/IP. */
int usbip_recv(struct socket *sock, void *buf, int size)
{
        int result;
        struct kvec iov = {.iov_base = buf, .iov_len = size};
        struct msghdr msg = {.msg_flags = MSG_NOSIGNAL};
        int total = 0;

        if (!sock || !buf || !size)
                return -EINVAL;

        iov_iter_kvec(&msg.msg_iter, ITER_DEST, &iov, 1, size);

        usbip_dbg_xmit("enter\n");

        do {
                sock->sk->sk_allocation = GFP_NOIO;
                sock->sk->sk_use_task_frag = false;

                result = sock_recvmsg(sock, &msg, MSG_WAITALL);
                if (result <= 0)
                        goto err;

                total += result;
        } while (msg_data_left(&msg));

        if (usbip_dbg_flag_xmit) {
                pr_debug("receiving....\n");
                usbip_dump_buffer(buf, size);
                pr_debug("received, osize %d ret %d size %zd total %d\n",
                         size, result, msg_data_left(&msg), total);
        }

        return total;

err:
        return result;
}
EXPORT_SYMBOL_GPL(usbip_recv);

/* there may be more cases to tweak the flags. */
static unsigned int tweak_transfer_flags(unsigned int flags)
{
        flags &= ~URB_NO_TRANSFER_DMA_MAP;
        return flags;
}

/*
 * USBIP driver packs URB transfer flags in PDUs that are exchanged
 * between Server (usbip_host) and Client (vhci_hcd). URB_* flags
 * are internal to kernel and could change. Where as USBIP URB flags
 * exchanged in PDUs are USBIP user API must not change.
 *
 * USBIP_URB* flags are exported as explicit API and client and server
 * do mapping from kernel flags to USBIP_URB*. Details as follows:
 *
 * Client tx path (USBIP_CMD_SUBMIT):
 * - Maps URB_* to USBIP_URB_* when it sends USBIP_CMD_SUBMIT packet.
 *
 * Server rx path (USBIP_CMD_SUBMIT):
 * - Maps USBIP_URB_* to URB_* when it receives USBIP_CMD_SUBMIT packet.
 *
 * Flags aren't included in USBIP_CMD_UNLINK and USBIP_RET_SUBMIT packets
 * and no special handling is needed for them in the following cases:
 * - Server rx path (USBIP_CMD_UNLINK)
 * - Client rx path & Server tx path (USBIP_RET_SUBMIT)
 *
 * Code paths:
 * usbip_pack_pdu() is the common routine that handles packing pdu from
 * urb and unpack pdu to an urb.
 *
 * usbip_pack_cmd_submit() and usbip_pack_ret_submit() handle
 * USBIP_CMD_SUBMIT and USBIP_RET_SUBMIT respectively.
 *
 * usbip_map_urb_to_usbip() and usbip_map_usbip_to_urb() are used
 * by usbip_pack_cmd_submit() and usbip_pack_ret_submit() to map
 * flags.
 */

struct urb_to_usbip_flags {
        u32 urb_flag;
        u32 usbip_flag;
};

#define NUM_USBIP_FLAGS 17

static const struct urb_to_usbip_flags flag_map[NUM_USBIP_FLAGS] = {
        {URB_SHORT_NOT_OK, USBIP_URB_SHORT_NOT_OK},
        {URB_ISO_ASAP, USBIP_URB_ISO_ASAP},
        {URB_NO_TRANSFER_DMA_MAP, USBIP_URB_NO_TRANSFER_DMA_MAP},
        {URB_ZERO_PACKET, USBIP_URB_ZERO_PACKET},
        {URB_NO_INTERRUPT, USBIP_URB_NO_INTERRUPT},
        {URB_FREE_BUFFER, USBIP_URB_FREE_BUFFER},
        {URB_DIR_IN, USBIP_URB_DIR_IN},
        {URB_DIR_OUT, USBIP_URB_DIR_OUT},
        {URB_DIR_MASK, USBIP_URB_DIR_MASK},
        {URB_DMA_MAP_SINGLE, USBIP_URB_DMA_MAP_SINGLE},
        {URB_DMA_MAP_PAGE, USBIP_URB_DMA_MAP_PAGE},
        {URB_DMA_MAP_SG, USBIP_URB_DMA_MAP_SG},
        {URB_MAP_LOCAL, USBIP_URB_MAP_LOCAL},
        {URB_SETUP_MAP_SINGLE, USBIP_URB_SETUP_MAP_SINGLE},
        {URB_SETUP_MAP_LOCAL, USBIP_URB_SETUP_MAP_LOCAL},
        {URB_DMA_SG_COMBINED, USBIP_URB_DMA_SG_COMBINED},
        {URB_ALIGNED_TEMP_BUFFER, USBIP_URB_ALIGNED_TEMP_BUFFER},
};

static unsigned int urb_to_usbip(unsigned int flags)
{
        unsigned int map_flags = 0;
        int loop;

        for (loop = 0; loop < NUM_USBIP_FLAGS; loop++) {
                if (flags & flag_map[loop].urb_flag)
                        map_flags |= flag_map[loop].usbip_flag;
        }

        return map_flags;
}

static unsigned int usbip_to_urb(unsigned int flags)
{
        unsigned int map_flags = 0;
        int loop;

        for (loop = 0; loop < NUM_USBIP_FLAGS; loop++) {
                if (flags & flag_map[loop].usbip_flag)
                        map_flags |= flag_map[loop].urb_flag;
        }

        return map_flags;
}

static void usbip_pack_cmd_submit(struct usbip_header *pdu, struct urb *urb,
                                  int pack)
{
        struct usbip_header_cmd_submit *spdu = &pdu->u.cmd_submit;

        /*
         * Some members are not still implemented in usbip. I hope this issue
         * will be discussed when usbip is ported to other operating systems.
         */
        if (pack) {
                /* map after tweaking the urb flags */
                spdu->transfer_flags = urb_to_usbip(tweak_transfer_flags(urb->transfer_flags));
                spdu->transfer_buffer_length    = urb->transfer_buffer_length;
                spdu->start_frame               = urb->start_frame;
                spdu->number_of_packets         = urb->number_of_packets;
                spdu->interval                  = urb->interval;
        } else  {
                urb->transfer_flags         = usbip_to_urb(spdu->transfer_flags);
                urb->transfer_buffer_length = spdu->transfer_buffer_length;
                urb->start_frame            = spdu->start_frame;
                urb->number_of_packets      = spdu->number_of_packets;
                urb->interval               = spdu->interval;
        }
}

static void usbip_pack_ret_submit(struct usbip_header *pdu, struct urb *urb,
                                  int pack)
{
        struct usbip_header_ret_submit *rpdu = &pdu->u.ret_submit;

        if (pack) {
                rpdu->status            = urb->status;
                rpdu->actual_length     = urb->actual_length;
                rpdu->start_frame       = urb->start_frame;
                rpdu->number_of_packets = urb->number_of_packets;
                rpdu->error_count       = urb->error_count;
        } else {
                urb->status             = rpdu->status;
                urb->actual_length      = rpdu->actual_length;
                urb->start_frame        = rpdu->start_frame;
                urb->number_of_packets = rpdu->number_of_packets;
                urb->error_count        = rpdu->error_count;
        }
}

void usbip_pack_pdu(struct usbip_header *pdu, struct urb *urb, int cmd,
                    int pack)
{
        switch (cmd) {
        case USBIP_CMD_SUBMIT:
                usbip_pack_cmd_submit(pdu, urb, pack);
                break;
        case USBIP_RET_SUBMIT:
                usbip_pack_ret_submit(pdu, urb, pack);
                break;
        default:
                /* NOT REACHED */
                pr_err("unknown command\n");
                break;
        }
}
EXPORT_SYMBOL_GPL(usbip_pack_pdu);

static void correct_endian_basic(struct usbip_header_basic *base, int send)
{
        if (send) {
                base->command   = cpu_to_be32(base->command);
                base->seqnum    = cpu_to_be32(base->seqnum);
                base->devid     = cpu_to_be32(base->devid);
                base->direction = cpu_to_be32(base->direction);
                base->ep        = cpu_to_be32(base->ep);
        } else {
                base->command   = be32_to_cpu(base->command);
                base->seqnum    = be32_to_cpu(base->seqnum);
                base->devid     = be32_to_cpu(base->devid);
                base->direction = be32_to_cpu(base->direction);
                base->ep        = be32_to_cpu(base->ep);
        }
}

static void correct_endian_cmd_submit(struct usbip_header_cmd_submit *pdu,
                                      int send)
{
        if (send) {
                pdu->transfer_flags = cpu_to_be32(pdu->transfer_flags);

                cpu_to_be32s(&pdu->transfer_buffer_length);
                cpu_to_be32s(&pdu->start_frame);
                cpu_to_be32s(&pdu->number_of_packets);
                cpu_to_be32s(&pdu->interval);
        } else {
                pdu->transfer_flags = be32_to_cpu(pdu->transfer_flags);

                be32_to_cpus(&pdu->transfer_buffer_length);
                be32_to_cpus(&pdu->start_frame);
                be32_to_cpus(&pdu->number_of_packets);
                be32_to_cpus(&pdu->interval);
        }
}

static void correct_endian_ret_submit(struct usbip_header_ret_submit *pdu,
                                      int send)
{
        if (send) {
                cpu_to_be32s(&pdu->status);
                cpu_to_be32s(&pdu->actual_length);
                cpu_to_be32s(&pdu->start_frame);
                cpu_to_be32s(&pdu->number_of_packets);
                cpu_to_be32s(&pdu->error_count);
        } else {
                be32_to_cpus(&pdu->status);
                be32_to_cpus(&pdu->actual_length);
                be32_to_cpus(&pdu->start_frame);
                be32_to_cpus(&pdu->number_of_packets);
                be32_to_cpus(&pdu->error_count);
        }
}

static void correct_endian_cmd_unlink(struct usbip_header_cmd_unlink *pdu,
                                      int send)
{
        if (send)
                pdu->seqnum = cpu_to_be32(pdu->seqnum);
        else
                pdu->seqnum = be32_to_cpu(pdu->seqnum);
}

static void correct_endian_ret_unlink(struct usbip_header_ret_unlink *pdu,
                                      int send)
{
        if (send)
                cpu_to_be32s(&pdu->status);
        else
                be32_to_cpus(&pdu->status);
}

void usbip_header_correct_endian(struct usbip_header *pdu, int send)
{
        __u32 cmd = 0;

        if (send)
                cmd = pdu->base.command;

        correct_endian_basic(&pdu->base, send);

        if (!send)
                cmd = pdu->base.command;

        switch (cmd) {
        case USBIP_CMD_SUBMIT:
                correct_endian_cmd_submit(&pdu->u.cmd_submit, send);
                break;
        case USBIP_RET_SUBMIT:
                correct_endian_ret_submit(&pdu->u.ret_submit, send);
                break;
        case USBIP_CMD_UNLINK:
                correct_endian_cmd_unlink(&pdu->u.cmd_unlink, send);
                break;
        case USBIP_RET_UNLINK:
                correct_endian_ret_unlink(&pdu->u.ret_unlink, send);
                break;
        default:
                /* NOT REACHED */
                pr_err("unknown command\n");
                break;
        }
}
EXPORT_SYMBOL_GPL(usbip_header_correct_endian);

static void usbip_iso_packet_correct_endian(
                struct usbip_iso_packet_descriptor *iso, int send)
{
        /* does not need all members. but copy all simply. */
        if (send) {
                iso->offset     = cpu_to_be32(iso->offset);
                iso->length     = cpu_to_be32(iso->length);
                iso->status     = cpu_to_be32(iso->status);
                iso->actual_length = cpu_to_be32(iso->actual_length);
        } else {
                iso->offset     = be32_to_cpu(iso->offset);
                iso->length     = be32_to_cpu(iso->length);
                iso->status     = be32_to_cpu(iso->status);
                iso->actual_length = be32_to_cpu(iso->actual_length);
        }
}

static void usbip_pack_iso(struct usbip_iso_packet_descriptor *iso,
                           struct usb_iso_packet_descriptor *uiso, int pack)
{
        if (pack) {
                iso->offset             = uiso->offset;
                iso->length             = uiso->length;
                iso->status             = uiso->status;
                iso->actual_length      = uiso->actual_length;
        } else {
                uiso->offset            = iso->offset;
                uiso->length            = iso->length;
                uiso->status            = iso->status;
                uiso->actual_length     = iso->actual_length;
        }
}

/* must free buffer */
struct usbip_iso_packet_descriptor*
usbip_alloc_iso_desc_pdu(struct urb *urb, ssize_t *bufflen)
{
        struct usbip_iso_packet_descriptor *iso;
        int np = urb->number_of_packets;
        ssize_t size = np * sizeof(*iso);
        int i;

        iso = kzalloc(size, GFP_KERNEL);
        if (!iso)
                return NULL;

        for (i = 0; i < np; i++) {
                usbip_pack_iso(&iso[i], &urb->iso_frame_desc[i], 1);
                usbip_iso_packet_correct_endian(&iso[i], 1);
        }

        *bufflen = size;

        return iso;
}
EXPORT_SYMBOL_GPL(usbip_alloc_iso_desc_pdu);

/* some members of urb must be substituted before. */
int usbip_recv_iso(struct usbip_device *ud, struct urb *urb)
{
        void *buff;
        struct usbip_iso_packet_descriptor *iso;
        int np = urb->number_of_packets;
        int size = np * sizeof(*iso);
        int i;
        int ret;
        int total_length = 0;

        if (!usb_pipeisoc(urb->pipe))
                return 0;

        /* my Bluetooth dongle gets ISO URBs which are np = 0 */
        if (np == 0)
                return 0;

        buff = kzalloc(size, GFP_KERNEL);
        if (!buff)
                return -ENOMEM;

        ret = usbip_recv(ud->tcp_socket, buff, size);
        if (ret != size) {
                dev_err(&urb->dev->dev, "recv iso_frame_descriptor, %d\n",
                        ret);
                kfree(buff);

                if (ud->side == USBIP_STUB || ud->side == USBIP_VUDC)
                        usbip_event_add(ud, SDEV_EVENT_ERROR_TCP);
                else
                        usbip_event_add(ud, VDEV_EVENT_ERROR_TCP);

                return -EPIPE;
        }

        iso = (struct usbip_iso_packet_descriptor *) buff;
        for (i = 0; i < np; i++) {
                usbip_iso_packet_correct_endian(&iso[i], 0);
                usbip_pack_iso(&iso[i], &urb->iso_frame_desc[i], 0);
                total_length += urb->iso_frame_desc[i].actual_length;
        }

        kfree(buff);

        if (total_length != urb->actual_length) {
                dev_err(&urb->dev->dev,
                        "total length of iso packets %d not equal to actual length of buffer %d\n",
                        total_length, urb->actual_length);

                if (ud->side == USBIP_STUB || ud->side == USBIP_VUDC)
                        usbip_event_add(ud, SDEV_EVENT_ERROR_TCP);
                else
                        usbip_event_add(ud, VDEV_EVENT_ERROR_TCP);

                return -EPIPE;
        }

        return ret;
}
EXPORT_SYMBOL_GPL(usbip_recv_iso);

/*
 * This functions restores the padding which was removed for optimizing
 * the bandwidth during transfer over tcp/ip
 *
 * buffer and iso packets need to be stored and be in propeper endian in urb
 * before calling this function
 */
void usbip_pad_iso(struct usbip_device *ud, struct urb *urb)
{
        int np = urb->number_of_packets;
        int i;
        int actualoffset = urb->actual_length;

        if (!usb_pipeisoc(urb->pipe))
                return;

        /* if no packets or length of data is 0, then nothing to unpack */
        if (np == 0 || urb->actual_length == 0)
                return;

        /*
         * if actual_length is transfer_buffer_length then no padding is
         * present.
         */
        if (urb->actual_length == urb->transfer_buffer_length)
                return;

        /*
         * loop over all packets from last to first (to prevent overwriting
         * memory when padding) and move them into the proper place
         */
        for (i = np-1; i > 0; i--) {
                actualoffset -= urb->iso_frame_desc[i].actual_length;
                memmove(urb->transfer_buffer + urb->iso_frame_desc[i].offset,
                        urb->transfer_buffer + actualoffset,
                        urb->iso_frame_desc[i].actual_length);
        }
}
EXPORT_SYMBOL_GPL(usbip_pad_iso);

/* some members of urb must be substituted before. */
int usbip_recv_xbuff(struct usbip_device *ud, struct urb *urb)
{
        struct scatterlist *sg;
        int ret = 0;
        int recv;
        int size;
        int copy;
        int i;

        if (ud->side == USBIP_STUB || ud->side == USBIP_VUDC) {
                /* the direction of urb must be OUT. */
                if (usb_pipein(urb->pipe))
                        return 0;

                size = urb->transfer_buffer_length;
        } else {
                /* the direction of urb must be IN. */
                if (usb_pipeout(urb->pipe))
                        return 0;

                size = urb->actual_length;
        }

        /* no need to recv xbuff */
        if (!(size > 0))
                return 0;

        if (size > urb->transfer_buffer_length)
                /* should not happen, probably malicious packet */
                goto error;

        if (urb->num_sgs) {
                copy = size;
                for_each_sg(urb->sg, sg, urb->num_sgs, i) {
                        int recv_size;

                        if (copy < sg->length)
                                recv_size = copy;
                        else
                                recv_size = sg->length;

                        recv = usbip_recv(ud->tcp_socket, sg_virt(sg),
                                                recv_size);

                        if (recv != recv_size)
                                goto error;

                        copy -= recv;
                        ret += recv;

                        if (!copy)
                                break;
                }

                if (ret != size)
                        goto error;
        } else {
                ret = usbip_recv(ud->tcp_socket, urb->transfer_buffer, size);
                if (ret != size)
                        goto error;
        }

        return ret;

error:
        dev_err(&urb->dev->dev, "recv xbuf, %d\n", ret);
        if (ud->side == USBIP_STUB || ud->side == USBIP_VUDC)
                usbip_event_add(ud, SDEV_EVENT_ERROR_TCP);
        else
                usbip_event_add(ud, VDEV_EVENT_ERROR_TCP);

        return -EPIPE;
}
EXPORT_SYMBOL_GPL(usbip_recv_xbuff);

static int __init usbip_core_init(void)
{
        return usbip_init_eh();
}

static void __exit usbip_core_exit(void)
{
        usbip_finish_eh();
        return;
}

module_init(usbip_core_init);
module_exit(usbip_core_exit);

MODULE_AUTHOR(DRIVER_AUTHOR);
MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_LICENSE("GPL");