USB Network Redirection protocol description version 0.7 (19 May 2014)

Revisions

---------

Version 0.1

-Initial version (released as initial RFC without a version number)

Version 0.2

-Version demo-ed at FOSDEM 2011

-Remove usb_redir_report_descriptor packet, as it is not possible to get

 the cached descriptors from the OS on all platforms and we can do without

-Replace vm-host with usb-guest

-Replace the synchroneous / asynchroneous commands nomenclature with

 control / data packets

-Move the packet id to the main packet header shared by all packets

-Add note: "All integers in the protocol are send over the pipe in least

 significant byte first order."

-Add note: "All structs are packed"

-s/data_size/length/

-Add an usb_redir_cancel_data_packet packet

-Add usb_redir_reset and usb_redir_reset_status packets

Version 0.3, released 14 July 2011

-First "stable" version, all later versions should be compatible with this

 version

-Add an usb_redir_device_connect packet

-Add an usb_redir_device_disconnect packet

-Add an usb_redir_interface_info packet

-Add an usb_redir_ep_info packet

-Add support for interrupt transfers, add the following packets:

 usb_redir_start_interrupt_receiving

 usb_redir_stop_interrupt_receiving

 usb_redir_interrupt_receiving_status

 usb_redir_interrupt_packet

-Add a list with the possible values for the status field

-Report usb_redir_stall as iso status error to indicate a stream stop

-Drop usb_redir_disconnect status, instead the usb-host should always

 send a usb_redir_device_disconnect packet on device disconnection. The

 reason behind this is that having to handle disconnection from data packet

 handlers make things unnecessarily hard for the usb-guest

-Drop usb_redir_reset_status, instead if reconnecting to the device fails

 after reset the usb-host will send a usb_redir_device_disconnect packet

Version 0.3.1, released 18 August 2011

- No protocol changes

Version 0.3.2, released  3 January 2012

-The usb_redir_device_connect_header has been extended with a

 device_version_bcd field. This is only send / received if both sides

 have the usb_redir_cap_connect_device_version capability

Version 0.3.3, released 12 January 2012

- No protocol changes

Version 0.4,   released 22 February 2012

- Add usb_redir_filter_reject and usb_redir_filter_filter packets and

  an usb_redir_cap_filter capability flag

- Add an usb_redir_device_disconnect_ack packet and

  an usb_redir_cap_device_disconnect_ack capability flag

Version 0.4.1, released 25 February 2012

- No protocol changes

Version 0.4.2, released  6 March 2012

- Add usb_redir_babble status code

- The usb_redir_ep_info_header has been extended with a max_packet_size field

  This is only send / received if both sides have the

  usb_redir_cap_ep_info_max_packet_size capability

Version 0.5,   released  7 September 2012

- Add the posibility to use 64 bits packet ids

Version 0.5.3, released  7 October 2012

- Extend the length field in bulk packets headers to 32 bits, the extra 16

  bits are only send / received if both sides have the

  usb_redir_cap_32bits_bulk_length capability

Version 0.6,   released 13 December 2012

- Add support for buffered bulk input, new packets:

  usb_redir_start_bulk_receiving, usb_redir_stop_bulk_receiving,

  usb_redir_bulk_receiving_status, usb_redir_buffered_bulk_packet

  New capability: usb_redir_cap_bulk_receiving

Version 0.7,   released 19 May 2014

- The usb_redir_ep_info_header has been extended with a max_streams field

  This is only send / received if both sides have the

  usb_redir_cap_bulk_streams capability.

- Change bulk_stream packet definitions to allow allocating / freeing

  streams on multiple endpoints in one go, technically this is a protocol

  change, but no-one has implemented usb_redir_cap_bulk_streams so far, so

  we can safely do this

USB redirection protocol version 0.7

------------------------------------

The protocol described in this document is meant for tunneling usb transfers

to a single usb device. Note: not an entire hub, only a single device.

The most significant use case for this is taking a usb device attached to

some machine "a" which acts as a client / viewer to a virtual machine "v"

hosted on another machine "b", and make the usb device show up inside the

virtual machine as if it were attached directly to the virtual machine "v".

The described protocol assumes a reliable ordered bidirectional transport is

available, for example a tcp socket. All integers in the protocol are send

over the pipe in least significant byte first order. All structs send over

the pipe are packed (no padding).

Definitions:

usb-device: The usb-device whose usb transfers are being tunneled.

usb-guest: The entity connecting to the usb-device and using it as if

    connected directly to it. For example a virtual machine running a guest

    os which accesses a usb-device over the network as if it is part of the

    virtual machine.

usb-host: The entity making the usb-device available for use by a usb-guest.

    For example a daemon on a machine which "exports" the usb-device over the

    network which then "appears" inside a virtual machine on another machine.

Basic packet structure / communication

--------------------------------------

Each packet exchanged between the usb-guest and the usb-host starts with a

usb_redir_header, followed by an optional packet type specific header

follow by optional additional data.

The usb_redir_header each packet starts with looks as follows:

struct usb_redir_header {

    uint32_t type;

    uint32_t length;

    uint32_t id;

}

Or, if both sides have the usb_redir_cap_64bits_ids capability, it looks as

follows!  :

struct usb_redir_header {

    uint32_t type;

    uint32_t length;

    uint64_t id;

}

type:    This identifies the type of packet, from the type enum

length:  Length of the optional type specific packet header + the optional

         additional data. Can be 0.

id:      A unique id, generated by the usb-guest when sending a packet,

         the usb-host will use the same id in its response packet, allowing

         the usb-guest to match responses to its original requests.

There are 2 types of packets:

1) control packets

2) data packets

Control packets are handled synchroneously inside the usb-host, it will hand

the request over to the host os and then *wait* for a response. The usb-host

will thus stop processing further packets. Where as for data packets the

usb-host hands them over to the host os with the request to let the usb-host

process know when there is a response from the usb-device.

Note that control packets should only be send to the usb-host when no data

packets are pending on the device / interface / endpoint affected by the

control packet. Any pending data packets will get dropped, and any active

iso streams / allocated bulk streams will get stopped / free-ed.

Packet type list

----------------

control packets:

usb_redir_hello

usb_redir_device_connect

usb_redir_device_disconnect

usb_redir_reset

usb_redir_interface_info

usb_redir_ep_info

usb_redir_set_configuration

usb_redir_get_configuration

usb_redir_configuration_status

usb_redir_set_alt_setting

usb_redir_get_alt_setting

usb_redir_alt_setting_status

usb_redir_start_iso_stream

usb_redir_stop_iso_stream

usb_redir_iso_stream_status

usb_redir_start_interrupt_receiving

usb_redir_stop_interrupt_receiving

usb_redir_interrupt_receiving_status

usb_redir_alloc_bulk_streams

usb_redir_free_bulk_streams

usb_redir_bulk_streams_status

usb_redir_cancel_data_packet

usb_redir_filter_reject

usb_redir_filter_filter

usb_redir_device_disconnect_ack

usb_redir_start_bulk_receiving

usb_redir_stop_bulk_receiving

usb_redir_bulk_receiving_status

data packets:

usb_redir_control_packet

usb_redir_bulk_packet

usb_redir_iso_packet

usb_redir_interrupt_packet

usb_redir_buffered_bulk_packet

Status code list

----------------

Many usb-host replies have a status field, this field can have the following

values:

enum {

    usb_redir_success,

    usb_redir_cancelled,    /* The transfer was cancelled */

    usb_redir_inval,        /* Invalid packet type / length / ep, etc. */

    usb_redir_ioerror,      /* IO error */

    usb_redir_stall,        /* Stalled */

    usb_redir_timeout,      /* Request timed out */

    usb_redir_babble,       /* The device has "babbled" */

};

Note that in future versions there may be additional status codes to signal

new / other *error* conditions. So any unknown status value should be

interpreted as an error.

usb_redir_hello

---------------

usb_redir_header.type:    usb_redir_hello

usb_redir_header.length:  <see description>

usb_redir_header.id:      0 (always as this is an unsolicited packet)

struct usb_redir_hello_header {

    char     version[64];

    uint32_t capabilities[0];

}

No packet type specific additional data.

A packet of this type is send by both sides as soon as a connection is

establised. It is mandatory that this packet is the first packet send by

both sides! This packet contains:

version:       A free form 0 terminated version string, useful for logging

               should not be parsed! Suggested format: "qemu 0.13",

               "usb-redir-daemon 0.1", etc.

capabilities:  A variable length array for announcing capabilities.

Note that since the peer caps are not known until the usb_redir_hello

packet is received, the hello packet always has 32 bits id fields!

The value of the length field depends on the size of the capabilities array.

If we cross the 32 capabilities count, it will go from 1 uint32_t to 2,

etc. the value is 64 + capabilities-array-size * sizeof(uint32_t).

Currently the following capabilities are defined:

enum {

    /* Supports USB 3 bulk streams */

    usb_redir_cap_bulk_streams,

    /* The device_connect packet has the device_version_bcd field */

    usb_redir_cap_connect_device_version,

    /* Supports usb_redir_filter_reject and usb_redir_filter_filter pkts */

    usb_redir_cap_filter,

    /* Supports the usb_redir_device_disconnect_ack packet */

    usb_redir_cap_device_disconnect_ack,

    /* The ep_info packet has the max_packet_size field */

    usb_redir_cap_ep_info_max_packet_size,

    /* Supports 64 bits ids in usb_redir_header */

    usb_redir_cap_64bits_ids,

    /* Supports 32 bits length in usb_redir_bulk_packet_header */

    usb_redir_cap_32bits_bulk_length,

    /* Supports bulk receiving / buffered bulk input */

    usb_redir_cap_bulk_receiving,

};

usb_redir_device_connect

------------------------

usb_redir_header.type:    usb_redir_device_connect

usb_redir_header.length:  sizeof(usb_redir_device_connect_header)

usb_redir_header.id:      0 (always as this is an unsolicited packet)

enum {

    usb_redir_speed_low,

    usb_redir_speed_full,

    usb_redir_speed_high,

    usb_redir_speed_super,

    usb_redir_speed_unknown = 255

}

struct usb_redir_device_connect_header {

    uint8_t speed;

    uint8_t device_class;

    uint8_t device_subclass;

    uint8_t device_protocol;

    uint16_t vendor_id;

    uint16_t product_id;

    uint16_t device_version_bcd;

}

No packet type specific additional data.

This packet gets send by the usb-host when a device becomes available (it is

possible for the usb-host to wait for a device to get plugged in).

The device_version_bcd field should only be send (and expected on receive)

when both sides have the usb_redir_cap_connect_device_version capability.

If this is not the case the length of the packet will be 2 bytes less!

Note that a usb-host may re-use the existing connection for a new / re-plugged

device in this case this packet can be send after a usb_redir_device_disconnect

message to notify the usb-guest that a new device is available.

Note the usbredir-host *must* first send usb_redir_ep_info followed by

usb_redir_interface_info before sending the usb_redir_device_connect_info!

usb_redir_device_disconnect

---------------------------

usb_redir_header.type:    usb_redir_device_disconnect

usb_redir_header.length:  0

usb_redir_header.id:      0 (always as this is an unsolicited packet)

No packet type specific header.

No packet type specific additional data.

This packet may be send by the usb-host to indicate that the device has been

disconnect (unplugged). Note on some platforms the usb-host may not become

aware of the disconnection until a usb packet is send to the device.

usb_redir_reset

---------------

usb_redir_header.type:    usb_redir_reset

usb_redir_header.length:  0

No packet type specific header.

No packet type specific additional data.

This packet can be send by the usb-guest to cause a reset of the usb

device. Note that of things go wrong the usb-host may be unable to re-connect

to the device after the reset! If this happens a usb_redir_device_disconnect

packet will be send by the usb-host.

usb_redir_interface_info

------------------------

usb_redir_header.type:    usb_redir_interface_info

usb_redir_header.length:  sizeof(usb_redir_interface_info_header)

usb_redir_header.id:      0 (always as this is an unsolicited packet)

struct usb_redir_interface_info_header {

    uint32_t interface_count;

    uint8_t interface[32];

    uint8_t interface_class[32];

    uint8_t interface_subclass[32];

    uint8_t interface_protocol[32];

}

No packet type specific additional data.

This packet gets send by the usb-host to inform the usb-guest about the

interfaces of the device. It contains the interface number, class and protocol

info for interface_count interfaces. This gets send after a (successful)

initial connection, set_config and set_alt_setting.

usb_redir_ep_info

-----------------

usb_redir_header.type:    usb_redir_ep_info

usb_redir_header.length:  sizeof(usb_redir_ep_info_header)

usb_redir_header.id:      0 (always as this is an unsolicited packet)

enum {

    /* Note these 4 match the usb spec! */

    usb_redir_type_control,

    usb_redir_type_iso,

    usb_redir_type_bulk,

    usb_redir_type_interrupt,

    usb_redir_type_invalid = 255

}

struct usb_redir_ep_info_header {

    uint8_t type[32];

    uint8_t interval[32];

    uint8_t interface[32];

    uint16_t max_packet_size[32];

    uint32_t max_streams[32];

}

No packet type specific additional data.

This packet gets send by the usb-host to let the usb-guest know the endpoint

type, interval and interface it belongs to for all possible endpoints,

first 0-15 out, then 0-15 in. This gets send after a (successful) initial

connection, set_config and set_alt_setting.

The max_packet_size field should only be send (and expected on receive)

when both sides have the usb_redir_cap_ep_info_max_packet_size capability.

If this is not the case the length of the packet will be 64 bytes less!

The max_streams field should only be send (and expected on receive)

when both sides have the usb_redir_cap_bulk_streams capability. If this is

not the case the length of the packet will be 128 bytes less!

Note implementations with the usb_redir_cap_bulk_streams capability must

always also have the usb_redir_cap_ep_info_max_packet_size capability.

Advertising usb_redir_cap_bulk_streams without

usb_redir_cap_ep_info_max_packet_size is not allowed!

usb_redir_set_configuration

---------------------------

usb_redir_header.type:    usb_redir_set_configuration

usb_redir_header.length:  sizeof(usb_redir_set_configuration_header)

struct usb_redir_set_configuration_header {

    uint8_t configuration;

}

No packet type specific additional data.

This packet can be send by the usb-guest to set (change) the active

configuration of the usb-device.

usb_redir_get_configuration

---------------------------

usb_redir_header.type:    usb_redir_get_configuration

usb_redir_header.length:  0

No packet type specific header.

No packet type specific additional data.

This packet can be send by the usb-guest to get (query) the active

configuration of the usb-device.

usb_redir_configuration_status

------------------------------

usb_redir_header.type:    usb_redir_configuration_status

usb_redir_header.length:  sizeof(usb_redir_configuration_status_header)

struct usb_redir_configuration_status_header {

    uint8_t status;

    uint8_t configuration;

}

No packet type specific additional data.

This is send by the usb-host in response to a usb_redir_set_configuration /

usb_redir_get_configuration packet. It reports a status code and on success

the resulting / active configuration.

Note that after a successful usb_redir_set_configuration command the

usbredir-host *must* first send usb_redir_ep_info followed by

usb_redir_interface_info before sending the usb_redir_configuration_status,

to ensure the usb-guest has the new info when it starts using the new

configuration.

usb_redir_set_alt_setting

-------------------------

usb_redir_header.type:    usb_redir_set_alt_setting

usb_redir_header.length:  sizeof(usb_redir_set_alt_setting_header)

struct usb_redir_set_alt_setting_header {

    uint8_t interface;

    uint8_t alt;

}

No packet type specific additional data.

This packet can be send by the usb-guest to set (change) the alt_setting of

interface <interface> to <alt>.

usb_redir_get_alt_setting

---------------------------

usb_redir_header.type:    usb_redir_get_alt_setting

usb_redir_header.length:  sizeof(usb_redir_get_alt_setting_header)

struct usb_redir_get_alt_setting_header {

    uint8_t interface;

}

No packet type specific additional data.

This packet can be send by the usb-guest to get (query) the active

alt_setting of an interface of the usb-device.

usb_redir_alt_setting_status

----------------------------

usb_redir_header.type:    usb_redir_alt_setting_status

usb_redir_header.length:  sizeof(usb_redir_alt_setting_status_header)

struct usb_redir_alt_setting_status_header {

    uint8_t status;

    uint8_t interface;

    uint8_t alt;

}

No packet type specific additional data.

This is send by the usb-host in response to a usb_redir_set_alt_setting /

usb_redir_get_alt_setting packet. It reports a status code, the affected

interface and on success the resulting / active alt_setting for that interface.

Note that after a successful usb_redir_set_alt_setting command the

usbredir-host *must* first send usb_redir_ep_info followed by

usb_redir_interface_info before sending the usb_redir_alt_setting_status,

to ensure the usb-guest has the new info when it starts using the new

alt setting.

usb_redir_start_iso_stream

--------------------------

usb_redir_header.type:    usb_redir_start_iso_stream

usb_redir_header.length:  sizeof(usb_redir_start_iso_stream_header)

struct usb_redir_start_iso_stream_header {

    uint8_t endpoint;

    uint8_t pkts_per_urb;

    uint8_t no_urbs;

}

No packet type specific additional data.

This packet can be send by the usb-guest to start a iso stream on the

designated endpoint of the usb-device.

This function allocates no_urbs urbs with pkts_per_urb iso packets/frames

per urb. For iso input endpoints these urbs will get submitted to the

device *immediately*, for iso output endpoints the usb-host will wait till

it has received (pkts_per_urb * no_urbs / 2) packets to fill its buffers,

before submitting the first urb.

usb_redir_stop_iso_stream

-------------------------

usb_redir_header.type:    usb_redir_stop_iso_stream

usb_redir_header.length:  sizeof(struct usb_redir_start_iso_stream_header)

struct usb_redir_stop_iso_stream_header {

    uint8_t endpoint;

}

No packet type specific additional data.

This packet can be send by the usb-guest to stop an iso stream on the

designated endpoint. This will cancel all pending urbs, flush the usb-host's

buffers and free all relevant resources. Note that the usb-guest can still

receive isoc data packets from an isoc in endpoint after sending this, as

some data packets may already be inside the transport pipe.

usb_redir_iso_stream_status

---------------------------

usb_redir_header.type:    usb_redir_iso_stream_status

usb_redir_header.length:  sizeof(usb_redir_iso_stream_status_header)

struct usb_redir_iso_stream_status_header {

    uint8_t status;

    uint8_t endpoint;

}

No packet type specific additional data.

This packet is send by the usb-host in response to a

usb_redir_start_iso_stream or usb_redir_stop_iso_stream packet. Note that

for the starting of output iso streams a success status only indicates that

all the buffers were successfully allocated, the actual stream is not

started until enough packets are buffered.

Note that this can also be send unsolicited by a usb-host in case of an

error with an iso output stream, see usb_redir_iso_packet.

To allow the usb-guest to detect if the stream was adversely stopped, the

usb-host will always report usb_redir_stall as status if the stream was

stopped for any reason other then an usb_redir_stop_iso_stream.

usb_redir_start_interrupt_receiving

-----------------------------------

usb_redir_header.type:    usb_redir_start_interrupt_receiving

usb_redir_header.length:  sizeof(usb_redir_start_interrupt_receiving_header)

struct usb_redir_start_interrupt_receiving_header {

    uint8_t endpoint;

}

No packet type specific additional data.

This packet can be send by the usb-guest to start receiving interrupts

from the designated endpoint of the usb-device.

This function is for *input* interrupt endpoints only. Input interrupt

endpoints need to be polled timely otherwise data may get lost. So for

input interrupt endpoints the usb-host takes care of the submitting and

re-submitting of urbs.

On receiving this packet the usb-host will start an interrupt transfer

to the endpoint using the interval and maxPacketSize from the descriptors.

When this transfer completes, the usb-host will send an

usb_redir_interrupt_packet to the usb-guest, and will re-submit the urb.

usb_redir_stop_interrupt_receiving

----------------------------------

usb_redir_header.type:    usb_redir_stop_interrupt_receiving

usb_redir_header.length:  sizeof(struct usb_redir_start_interrupt_receiving_header)

struct usb_redir_stop_interrupt_receiving_header {

    uint8_t endpoint;

}

No packet type specific additional data.

This packet can be send by the usb-guest to stop interrupt receiving on the

designated endpoint. This will cancel the pending urb. Note that the usb-guest

can still receive usb_redir_interrupt_packet-s after sending this, as

some data packets may already be inside the transport pipe.

usb_redir_interrupt_receiving_status

------------------------------------

usb_redir_header.type:    usb_redir_interrupt_receiving_status

usb_redir_header.length:  sizeof(usb_redir_interrupt_receiving_status_header)

struct usb_redir_interrupt_receiving_status_header {

    uint8_t status;

    uint8_t endpoint;

}

No packet type specific additional data.

This packet is send by the usb-host in response to a

usb_redir_start_interrupt_receiving or usb_redir_stop_interrupt_receiving

packet.

Note that this can also be send unsolicited by a usb-host in case of an

error re-submitting the interrupt urb.

To allow the usb-guest to detect if the stream was adversely stopped, the

usb-host will always report usb_redir_stall as status if the stream was

stopped for any reason other then an usb_redir_stop_interrupt_receiving.

usb_redir_alloc_bulk_streams

----------------------------

usb_redir_header.type:    usb_redir_alloc_bulk_streams

usb_redir_header.length:  sizeof(usb_redir_alloc_bulk_streams_header)

struct usb_redir_alloc_bulk_streams_header {

    uint32_t endpoints; /* bitmask indicating on which eps to alloc streams */

    uint32_t no_streams;

}

No packet type specific additional data.

This packet can be send by the usb-guest to the usb-host to request

that the usb-host allocates IDs so the usb-guest can use up to no_streams

stream IDs on the endpoints indicated by the endpoints bitmask. Endpoints in

the bitmask are indicated by bit number (0-31) using the same numbering as

in usb_redir_ep_info_header.

usb_redir_free_bulk_streams

----------------------------

usb_redir_header.type:    usb_redir_free_bulk_streams

usb_redir_header.length:  sizeof(usb_redir_free_bulk_streams_header)

struct usb_redir_free_bulk_streams_header {

    uint32_t endpoints; /* bitmask indicating on which eps to free streams */

}

No packet type specific additional data.

This packet can be send by the usb-guest to the usb-host to free any

bulk streams previously allocated on the endpoints indicated by the

endpoints bitmask.

usb_redir_bulk_streams_status

-----------------------------

usb_redir_header.type:    usb_redir_bulk_streams_status

usb_redir_header.length:  sizeof(usb_redir_bulk_streams_status_header)

struct usb_redir_bulk_streams_status_header {

    uint32_t endpoints; /* bitmask indicating eps this status message is for */

    uint32_t no_streams;

    uint8_t status;

}

No packet type specific additional data.

This packet is send by the usb-host in response to a

usb_redir_alloc_bulk_streams or usb_redir_free_bulk_streams packet.

For usb_redir_alloc_bulk_streams responses no_streams will be the no_streams

passed to the usb_redir_alloc_bulk_streams packet. usb-hosts are not allowed

to return less streams then requested! For usb_redir_free_bulk_streams

responses no_streams will be 0.

On a success status in response to a usb_redir_alloc_bulk_streams

the usb-guest may use stream ids 1 through no_streams.

usb_redir_start_bulk_receiving

------------------------------

usb_redir_header.type:    usb_redir_start_bulk_receiving

usb_redir_header.length:  sizeof(usb_redir_start_bulk_receiving_header)

struct usb_redir_start_bulk_receiving_header {

    uint32_t stream_id;

    uint32_t bytes_per_transfer;

    uint8_t endpoint;

    uint8_t no_transfers;

}

No packet type specific additional data.

This packet can be send by the usb-guest to start buffered reading from a

bulk endpoint.

Upon receiving this packet the usb-host will submit no_transfers bulk in

transfer of bytes_per_transfer each to the designated endpoint of the

usb-device. Upon completion of a transfer the usb-host will send an

usb_redir_buffered_bulk_packet with the received data to the usb-guest,

and immediately re-submit the completed transfer.

Note bytes_per_transfer must be a multiple of the endpoints max_packet_size.

Note this packet should only be send to usb-hosts with the

usb_redir_cap_bulk_receiving capability.

usb_redir_stop_bulk_receiving

-----------------------------

usb_redir_header.type:    usb_redir_stop_bulk_receiving

usb_redir_header.length:  sizeof(usb_redir_stop_bulk_receiving_header)

struct usb_redir_stop_bulk_receiving_header {

    uint32_t stream_id;

    uint8_t endpoint;

}

No packet type specific additional data.

This packet can be send by the usb-guest to stop bulk receiving on the

designated endpoint. This will cancel all pending transfers. Note that the

usb-guest can still receive usb_redir_bulk_packet-s after sending this, as

some data packets may already be inside the transport pipe.

Note this packet should only be send to usb-hosts with the

usb_redir_cap_bulk_receiving capability.

usb_redir_bulk_receiving_status

-------------------------------

usb_redir_header.type:    usb_redir_bulk_receiving_status

usb_redir_header.length:  sizeof(usb_redir_bulk_receiving_status_header)

struct usb_redir_bulk_receiving_status_header {

    uint32_t stream_id;

    uint8_t endpoint;

    uint8_t status;

}

No packet type specific additional data.

This packet is send by the usb-host in response to a

usb_redir_start_bulk_receiving or usb_redir_stop_bulk_receiving packet.

Note that this can also be send unsolicited by an usb-host in case of an

error re-submitting the bulk transfer.

To allow the usb-guest to detect if the stream was adversely stopped, the

usb-host will always report usb_redir_stall as status if the stream was

stopped for any reason other then an usb_redir_stop_interrupt_receiving.

Note this packet should only be send to usb-guests with the

usb_redir_cap_bulk_receiving capability.

usb_redir_cancel_data_packet

----------------------------

usb_redir_header.type:    usb_redir_cancel_data_packet

usb_redir_header.id       <id of packet to cancel>

usb_redir_header.length:  0

No packet type specific header.

No packet type specific additional data.

This packet can be send by the usb-guest to cancel an earlier send data

packet, the id should be set to the id used when sending the packet the

guest now wishes to cancel.

Note that the usb-guest will always receive back a data packet of the same type

and with the same id, the usb-guest can check if the packet completed

normally (before the cancel packet was processed by the usb-host), or was

cancelled by looking at the return data packet's status field.

usb_redir_filter_reject

-----------------------

usb_redir_header.type:    usb_redir_filter_reject

usb_redir_header.length:  0

usb_redir_header.id:      0 (always as this is an unsolicited packet)

No packet type specific header.

No packet type specific additional data.

This packet is send by the usb-guest after receiving a usb_redir_device_connect

or usb_redir_interface_info packet which was rejected by an usb-guest side

device filter. This packet should only be send to usb-hosts with the

usb_redir_cap_filter capability.

usb_redir_filter_filter

-----------------------

usb_redir_header.type:    usb_redir_filter_filter

usb_redir_header.length:  string-length + 1 (for 0 termination)

usb_redir_header.id:      0 (always as this is an unsolicited packet)

No packet type specific header.

The additional data contains a 0 terminated usredirfilter string.

This packet can be send directly after the hello packet to inform the other

side that a filter is in place and some devices may be rejected.

An usredirfilter consists of one or more rules, where in string form each rule

has the following format:

   <class>,<vendor>,<product>,<version>,<allow>

Values can be either in decimal format, or in hexadecimal format pre-fixed

with 0x, a value of -1 can be used to allow any value.

All rules of a filter are concatenated, separated by the '|' character

to form a single usredirfilter string:

   <rule1>|<rule2>|<rule3>

If a device matches none of the rules the result of the filter is deny and

the device will be rejected.

For more info on filtering see usbredirfilter.h

This packet should only be send to peers with the usb_redir_cap_filter

capability.

usb_redir_device_disconnect_ack

-------------------------------

usb_redir_header.type:    usb_redir_device_disconnect_ack

usb_redir_header.length:  0

usb_redir_header.id:      0 (as the id of the device_disconnect is always 0)

No packet type specific header.

No packet type specific additional data.