Linx.Netlink.Message (Linx v0.1.0)

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A netlink message — the nlmsghdr header (include/uapi/linux/netlink.h) and its payload — and the framing codec for it.

Every netlink message, of every protocol family, has the same 16-byte header:

0       4      6      8            12            16
+-------+------+------+------------+------------+----- ... -----+
|  len  | type | flags|    seq     |    pid     |    payload    |
+-------+------+------+------------+------------+----- ... -----+

All fields are in native byte order; len covers the header and payload. This module frames a message for sending and splits a received buffer back into messages. It does not interpret type — that is a protocol family's job — beyond using each message's len to find the next one.

A single receive can carry several messages — notably a multipart dump batch — so decode/1 returns a list.

Summary

Types

t()

Functions

decode(binary)

Decodes a received buffer into its list of messages, in order.

encode(message)

Encodes a message into its on-the-wire binary, computing nlmsg_len.

Types

t()

@type t() :: %Linx.Netlink.Message{
  flags: 0..65535,
  payload: binary(),
  pid: non_neg_integer(),
  seq: non_neg_integer(),
  type: 0..65535
}

Functions

decode(binary)

@spec decode(binary()) :: [t()]

Decodes a received buffer into its list of messages, in order.

A trailing run too short to form a header is ignored (alignment padding). Raises ArgumentError if a message's nlmsg_len overruns the buffer.

encode(message)

@spec encode(t()) :: binary()

Encodes a message into its on-the-wire binary, computing nlmsg_len.

The result is padded to the 4-byte alignment boundary, so encoded messages concatenate into a valid multi-message buffer.