Spice server channel Registration

1. server-side channel implementation

1. The server registers the channel.

Server channel type

enum {    SPICE_CHANNEL_MAIN = 1,    SPICE_CHANNEL_DISPLAY,    SPICE_CHANNEL_INPUTS,    SPICE_CHANNEL_CURSOR,    SPICE_CHANNEL_PLAYBACK,    SPICE_CHANNEL_RECORD,    SPICE_CHANNEL_TUNNEL,    SPICE_CHANNEL_SMARTCARD,    SPICE_CHANNEL_USBREDIR,    SPICE_CHANNEL_PORT,    SPICE_END_CHANNEL};

 

The most critical data structure of the server is redsstate. Another example is spiceserver. The server maintains a global redsstate variable to store global data. The global data structure is created by qemu during coreinterface initialization and passed to libspice through the VDI interface.

A data member in redsstate is channel * channels. The server maintains a channel linked list through this variable. All channels supported by the server must be registered through reds_register_channel. Except that inputchannle is registered in spice_server_init (that is, registered during coreinterface initialization), other channels are initialized on qemu for Virtual Devices, you have registered a VDI instance by calling the spice_server_add_interface function, as shown below:

// Register in container: Register in container // spice_server_add_interface (partition) red_dispatcher_init: Register in spice_channel_display, container // container (partition) snd_attach_playback: Container // spice_server_add_interface (partition) register in snd_attach_record: spice_channel_record // spice_server_add_interface (spice_interface_net_wire) red_tunnel_attach: spice_channel_tunnel

Registering a channel is to initialize a channel object and insert it into the channels ring of redsstate for subsequent access. The specific channel structure is as follows:

struct RedChannel {    uint32_t type;    uint32_t id;    uint32_t refs;    RingItem link; // channels link for reds    SpiceCoreInterface *core;    int handle_acks;    // RedChannel will hold only connected channel clients (logic - when pushing pipe item to all channel clients, there    // is no need to go over disconnect clients)    // . While client will hold the channel clients till it is destroyed    // and then it will destroy them as well.    // However RCC still holds a reference to the Channel.    // Maybe replace these logic with ref count?    // TODO: rename to 'connected_clients'?    Ring clients;    uint32_t clients_num;    OutgoingHandlerInterface outgoing_cb;    IncomingHandlerInterface incoming_cb;    ChannelCbs channel_cbs;    ClientCbs client_cbs;    RedChannelCapabilities local_caps;    uint32_t migration_flags;    void *data;    // TODO: when different channel_clients are in different threads from Channel -> need to protect!    pthread_t thread_id;#ifdef RED_STATISTICS    uint64_t *out_bytes_counter;#endif};