Sending a controller role-status message to the controller

Controller role-status messages (OFPT_ROLE_STATUS) are sent from the switch to the set of controllers when the role of a controller is changed as a result of an OFPT_ROLE_REQUEST message. For example, if there are three the controllers connected to a switch (say controller1, controller2, and controller3) and controller1 sends an OFPT_ROLE_REQUEST message to the switch, then the switch should send an OFPT_ROLE_STATUS message to controller2 and controller3.

/* Role status event message. */
struct ofp_role_status {
struct ofp_header header; /* Type OFPT_ROLE_REQUEST / 
                           * OFPT_ROLE_REPLY. */
uint32_t role;            /* One of OFPCR_ROLE_*. */
uint8_t reason;           /* One of OFPCRR_*. */
uint8_t pad[3];           /* Align to 64 bits. */
uint64_t generation_id;   /* Master...