[Spice-devel] [PATCH spice-protocol v2 1/4] Add protocol to send streams to server

[Jonathon Jongsma]

On Thu, 2017-08-10 at 20:51 +0100, Frediano Ziglio wrote:
> This protocol allows a guest to send a video stream to the server.
> 
> Signed-off-by: Frediano Ziglio <fziglio at redhat.com>
> ---
>  spice/Makefile.am     |   1 +
>  spice/stream-device.h | 128
> ++++++++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 129 insertions(+)
>  create mode 100644 spice/stream-device.h
> 
> diff --git a/spice/Makefile.am b/spice/Makefile.am
> index a54ae89..4f9a607 100644
> --- a/spice/Makefile.am
> +++ b/spice/Makefile.am
> @@ -19,6 +19,7 @@ spice_protocol_include_HEADERS =		\
>  	types.h					\
>  	vd_agent.h				\
>  	vdi_dev.h				\
> +	stream-device.h				\
>  	$(NULL)
>  
>  -include $(top_srcdir)/git.mk
> diff --git a/spice/stream-device.h b/spice/stream-device.h
> new file mode 100644
> index 0000000..2441ac1
> --- /dev/null
> +++ b/spice/stream-device.h
> @@ -0,0 +1,128 @@
> +/*
> +   Copyright (C) 2017 Red Hat, Inc.
> +
> +   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.
> +       * Neither the name of the copyright holder nor the names of
> its
> +         contributors may be used to endorse or promote products
> derived
> +         from this software without specific prior written
> permission.
> +
> +   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER AND
> CONTRIBUTORS "AS
> +   IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
> LIMITED
> +   TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
> +   PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
> COPYRIGHT
> +   HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
> INCIDENTAL,
> +   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
> +   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
> USE,
> +   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
> ANY
> +   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
> TORT
> +   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
> USE
> +   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
> DAMAGE.
> +*/
> +
> +/*
> + * This header contains definition for the device that
> + * allows to send streamed data to the server.
> + *
> + * The device is currently implemented as a VirtIO port inside the
> + * guest. The guest should open that device to use this protocol to
> + * communicate with the host.
> + * The name of the port is "com.redhat.stream.0".
> + */
> +
> +#ifndef SPICE_STREAM_DEVICE_H_
> +#define SPICE_STREAM_DEVICE_H_
> +
> +#include <spice/types.h>
> +
> +/*
> + * Structures are all "naturally aligned"
> + * containing integers up to 64 bit.
> + * All numbers are in little endian format.
> + *
> + * The protocol can be defined by these states:
> + * - Initial. Device just opened. Guest should wait

missing "for". Guests should wait for a message...

> + *   a message from the host;
> + * - Idle. No streaming allowed;
> + * - Ready. Server sent list of possible codecs;
> + * - Streaming. Stream active, enabled by the guest.
> + */
> +
> +/* version of the protocol */
> +#define STREAM_DEVICE_PROTOCOL 1
> +
> +typedef struct StreamDevHeader {
> +    /* should be STREAM_DEVICE_PROTOCOL */
> +    uint8_t protocol_version;
> +    /* reserved, should be set to 0 */
> +    uint8_t padding;
> +    /* as defined in StreamDevType enumeration */
> +    uint16_t type;
> +    /* size of the following message.
> +     * A message of type STREAM_TYPE_XXX_YYY is represented with a
> +     * corresponding StreamMsgXxxYyy structure. */
> +    uint32_t size;
> +} StreamDevHeader;
> +
> +typedef enum StreamDevType {
> +    /* invalid, do not use */
> +    STREAM_TYPE_INVALID = 0,
> +    /* allows to send version information */
> +    STREAM_TYPE_CAPABILITIES,
> +    /* send screen resolution */
> +    STREAM_TYPE_FORMAT,
> +    /* stream data */
> +    STREAM_TYPE_DATA,
> +} StreamDevType;

The name StreamDevType makes it sound like it's a type of stream
device. I think a better name would be something like
StreamDevMessageType or StreamMessageType since these are message
types.

> +
> +/* Generic extension capabilities.
> + * This is a set of bit to specify which capability host and guest
> supports.

bit -> bits
capability -> capabilities
supports -> support

> + * This message is sent by the host to the guest or by the guest to
> the host.
> + * Should be sent as first message.
> + * If not sent means that guest/host doesn't support any extension.

"If it is not sent, it means"...

> + * Guest should sent this as a reply from same type of message

sent -> send

> + * from the host.
> + * This message should be limited to 1024 bytes. This allows
> + * plenty of negotiations.
> + *
> + * States allowed: Initial(host), Idle(guest)
> + *   state will change to Idle.
> + */
> +typedef struct StreamMsgCapabilities {
> +    uint8_t capabilities[0];
> +} StreamMsgCapabilities;
> +
> +/* Define the format of the stream, start a new stream.
> + * This message is sent by the guest to the host to
> + * tell the host the new stream format.
> + *
> + * States allowed: Ready
> + *   state will change to Streaming.
> + */
> +typedef struct StreamMsgFormat {
> +    /* screen resolution/stream size */
> +    uint32_t width;
> +    uint32_t height;
> +    /* as defined in SpiceVideoCodecType enumeration */
> +    uint8_t codec;
> +    uint8_t padding1[3];
> +} StreamMsgFormat;
> +
> +/* This message contains just raw data stream.
> + * This message is sent by the guest to the host.
> + *
> + * States allowed: Streaming
> + */
> +typedef struct StreamMsgData {
> +    uint8_t data[0];
> +} StreamMsgData;
> +
> +#endif /* SPICE_STREAM_DEVICE_H_ */