net/hub.c

/*
 * Hub net client
 *
 * Copyright IBM, Corp. 2012
 *
 * Authors:
 *  Stefan Hajnoczi   <stefanha@linux.vnet.ibm.com>
 *  Zhi Yong Wu       <wuzhy@linux.vnet.ibm.com>
 *
 * This work is licensed under the terms of the GNU LGPL, version 2 or later.
 * See the COPYING.LIB file in the top-level directory.
 *
 */

#include "monitor.h"
#include "net.h"
#include "hub.h"

/*
 * A hub broadcasts incoming packets to all its ports except the source port.
 * Hubs can be used to provide independent network segments, also confusingly
 * named the QEMU 'vlan' feature.
 */

typedef struct NetHub NetHub;

typedef struct NetHubPort {
    VLANClientState nc;
    QLIST_ENTRY(NetHubPort) next;
    NetHub *hub;
    int id;
} NetHubPort;

struct NetHub {
    int id;
    QLIST_ENTRY(NetHub) next;
    int num_ports;
    QLIST_HEAD(, NetHubPort) ports;
};

static QLIST_HEAD(, NetHub) hubs = QLIST_HEAD_INITIALIZER(&hubs);

static ssize_t net_hub_receive(NetHub *hub, NetHubPort *source_port,
                               const uint8_t *buf, size_t len)
{
    NetHubPort *port;

    QLIST_FOREACH(port, &hub->ports, next) {
        if (port == source_port) {
            continue;
        }

        qemu_send_packet(&port->nc, buf, len);
    }
    return len;
}

static ssize_t net_hub_receive_iov(NetHub *hub, NetHubPort *source_port,
                                   const struct iovec *iov, int iovcnt)
{
    NetHubPort *port;
    ssize_t ret = 0;

    QLIST_FOREACH(port, &hub->ports, next) {
        if (port == source_port) {
            continue;
        }

        ret = qemu_sendv_packet(&port->nc, iov, iovcnt);
    }
    return ret;
}

static NetHub *net_hub_new(int id)
{
    NetHub *hub;

    hub = g_malloc(sizeof(*hub));
    hub->id = id;
    hub->num_ports = 0;
    QLIST_INIT(&hub->ports);

    QLIST_INSERT_HEAD(&hubs, hub, next);

    return hub;
}

static ssize_t net_hub_port_receive(VLANClientState *nc,
                                    const uint8_t *buf, size_t len)
{
    NetHubPort *port = DO_UPCAST(NetHubPort, nc, nc);

    return net_hub_receive(port->hub, port, buf, len);
}

static ssize_t net_hub_port_receive_iov(VLANClientState *nc,
                                        const struct iovec *iov, int iovcnt)
{
    NetHubPort *port = DO_UPCAST(NetHubPort, nc, nc);

    return net_hub_receive_iov(port->hub, port, iov, iovcnt);
}

static void net_hub_port_cleanup(VLANClientState *nc)
{
    NetHubPort *port = DO_UPCAST(NetHubPort, nc, nc);

    QLIST_REMOVE(port, next);
}

static NetClientInfo net_hub_port_info = {
    .type = NET_CLIENT_OPTIONS_KIND_HUBPORT,
    .size = sizeof(NetHubPort),
    .receive = net_hub_port_receive,
    .receive_iov = net_hub_port_receive_iov,
    .cleanup = net_hub_port_cleanup,
};

static NetHubPort *net_hub_port_new(NetHub *hub, const char *name)
{
    VLANClientState *nc;
    NetHubPort *port;
    int id = hub->num_ports++;
    char default_name[128];

    if (!name) {
        snprintf(default_name, sizeof(default_name),
                 "hub%dport%d", hub->id, id);
        name = default_name;
    }

    nc = qemu_new_net_client(&net_hub_port_info, NULL, NULL, "hub", name);
    port = DO_UPCAST(NetHubPort, nc, nc);
    port->id = id;
    port->hub = hub;

    QLIST_INSERT_HEAD(&hub->ports, port, next);

    return port;
}

/**
 * Create a port on a given hub
 * @name: Net client name or NULL for default name.
 *
 * If there is no existing hub with the given id then a new hub is created.
 */
VLANClientState *net_hub_add_port(int hub_id, const char *name)
{
    NetHub *hub;
    NetHubPort *port;

    QLIST_FOREACH(hub, &hubs, next) {
        if (hub->id == hub_id) {
            break;
        }
    }

    if (!hub) {
        hub = net_hub_new(hub_id);
    }

    port = net_hub_port_new(hub, name);
    return &port->nc;
}

/**
 * Print hub configuration
 */
void net_hub_info(Monitor *mon)
{
    NetHub *hub;
    NetHubPort *port;

    QLIST_FOREACH(hub, &hubs, next) {
        monitor_printf(mon, "hub %d\n", hub->id);
        QLIST_FOREACH(port, &hub->ports, next) {
            monitor_printf(mon, "    port %d peer %s\n", port->id,
                           port->nc.peer ? port->nc.peer->name : "<none>");
        }
    }
}

/**
 * Get the hub id that a client is connected to
 *
 * @id              Pointer for hub id output, may be NULL
 */
int net_hub_id_for_client(VLANClientState *nc, int *id)
{
    NetHubPort *port;

    if (nc->info->type == NET_CLIENT_OPTIONS_KIND_HUBPORT) {
        port = DO_UPCAST(NetHubPort, nc, nc);
    } else if (nc->peer != NULL && nc->peer->info->type ==
            NET_CLIENT_OPTIONS_KIND_HUBPORT) {
        port = DO_UPCAST(NetHubPort, nc, nc->peer);
    } else {
        return -ENOENT;
    }

    if (id) {
        *id = port->hub->id;
    }
    return 0;
}

int net_init_hubport(const NetClientOptions *opts, const char *name,
                     VLANClientState *peer)
{
    const NetdevHubPortOptions *hubport;

    assert(opts->kind == NET_CLIENT_OPTIONS_KIND_HUBPORT);
    hubport = opts->hubport;

    /* Treat hub port like a backend, NIC must be the one to peer */
    if (peer) {
        return -EINVAL;
    }

    net_hub_add_port(hubport->hubid, name);
    return 0;
}