pdl/netlink.pdl

// PDL grammar file for netlink packet format.
//
// This only includes definitions necessary for the mac80211_hwsim
// use case.
//
// See
//   - [RFC 3549](https://datatracker.ietf.org/doc/html/rfc3549)
//   - netlink.h


// Host byte order
little_endian_packets

// Netlink Message Header

struct NlMsgHdr {
    nlmsg_len : 32,             // Length of message including header
    nlmsg_type : 16,            // Message type identifier
    nlmsg_flags : 16,           // Flags (NLM_F_)
    nlmsg_seq : 32,             // Sequence number
    nlmsg_pid : 32,             // Sending process port ID
}

// Netlink Attribute Header

/*
 *  <------- NLA_HDRLEN ------> <-- NLA_ALIGN(payload)-->
 * +---------------------+- - -+- - - - - - - - - -+- - -+
 * |        Header       | Pad |     Payload       | Pad |
 * |   (struct nlattr)   | ing |                   | ing |
 * +---------------------+- - -+- - - - - - - - - -+- - -+
 *  <-------------- nlattr->nla_len -------------->
 */

/*
 * nla_type (16 bits)
 * +---+---+-------------------------------+
 * | N | O | Attribute Type                |
 * +---+---+-------------------------------+
 * N := Carries nested attributes
 * O := Payload stored in network byte order
 *
 * Note: The N and O flag are mutually exclusive.
 */

// Base netlink attribute TLV header.

struct NlAttrHdr {
    nla_len : 16,
    nla_type: 14,
    nla_m : 1,
    nla_o : 1,
}