【OVS2.5.0源码分析】openflow连接实现分析（1）

openflow连接有两个用途： 1）与controller连接；2）提供给ovs-ofctl工具配置流表等。

我们先看连接的初始化过程，配置入口是bridge_reconfigure函数。

1、bridge_reconfigure函数

    collect_in_band_managers(ovs_cfg, &managers, &n_managers);    //收集配置的manager信息
    HMAP_FOR_EACH (br, node, &all_bridges) {
        struct port *port;

        /* We need the datapath ID early to allow LACP ports to use it as the
         * default system ID. */
        bridge_configure_datapath_id(br);

        HMAP_FOR_EACH (port, hmap_node, &br->ports) {
            struct iface *iface;

            port_configure(port);

            LIST_FOR_EACH (iface, port_elem, &port->ifaces) {
                iface_set_ofport(iface->cfg, iface->ofp_port);
                /* Clear eventual previous errors */
                ovsrec_interface_set_error(iface->cfg, NULL);
                iface_configure_cfm(iface);
                iface_configure_qos(iface, port->cfg->qos);
                iface_set_mac(br, port, iface);
                ofproto_port_set_bfd(br->ofproto, iface->ofp_port,
                                     &iface->cfg->bfd);
                ofproto_port_set_lldp(br->ofproto, iface->ofp_port,
                                      &iface->cfg->lldp);
            }
        }
        bridge_configure_mirrors(br);
        bridge_configure_forward_bpdu(br);
        bridge_configure_mac_table(br);
        bridge_configure_mcast_snooping(br);
        bridge_configure_remotes(br, managers, n_managers);   //配置入口
        bridge_configure_netflow(br);
        bridge_configure_sflow(br, &sflow_bridge_number);
        bridge_configure_ipfix(br);
        bridge_configure_spanning_tree(br);
        bridge_configure_tables(br);
        bridge_configure_dp_desc(br);
        bridge_configure_aa(br);
    }

2、bridge_configure_remote函数

static void
bridge_configure_remotes(struct bridge *br,
                         const struct sockaddr_in *managers, size_t n_managers)
{
    bool disable_in_band;

    struct ovsrec_controller **controllers;
    size_t n_controllers;

    enum ofproto_fail_mode fail_mode;

    struct ofproto_controller *ocs;
    size_t n_ocs;
    size_t i;

    /* Check if we should disable in-band control on this bridge. */
    disable_in_band = smap_get_bool(&br->cfg->other_config, "disable-in-band",
                                    false);

    /* Set OpenFlow queue ID for in-band control. */
    ofproto_set_in_band_queue(br->ofproto,
                              smap_get_int(&br->cfg->other_config,
                                           "in-band-queue", -1));

    if (disable_in_band) {
        ofproto_set_extra_in_band_remotes(br->ofproto, NULL, 0);
    } else {
        ofproto_set_extra_in_band_remotes(br->ofproto, managers, n_managers);
    }

    n_controllers = bridge_get_controllers(br, &controllers);     //获取controller配置信息

    ocs = xmalloc((n_controllers + 1) * sizeof *ocs);
    n_ocs = 0;

    bridge_ofproto_controller_for_mgmt(br, &ocs[n_ocs++]);     //第1个，本质上不是controller，是作为管理供ovs-ofctl工具进行连接，使用punix
    for (i = 0; i < n_controllers; i++) {
        struct ovsrec_controller *c = controllers[i];

        if (!strncmp(c->target, "punix:", 6)
            || !strncmp(c->target, "unix:", 5)) {
            static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5);