Reference

link_event.lua

#!/usr/bin/env eco

local hex = require 'eco.encoding.hex'
local rtnl = require 'eco.rtnl'
local nl = require 'eco.nl'

local function print_event(nlh, msg)
    if nlh.type == rtnl.RTM_NEWLINK then
        print('new link')
    elseif nlh.type == rtnl.RTM_DELLINK then
        print('del link')
    end

    local info = rtnl.parse_ifinfomsg(msg)
    for k, v in pairs(info) do
        if k == 'flags' or k == 'change' then
            print(k .. ':', string.format('0x%x', v))
        else
            print(k .. ':', v)
        end
    end

    if info.flags & rtnl.IFF_RUNNING > 0 then
        print('RUNNING')
    else
        print('NOT RUNNING')
    end

    local attrs = msg:parse_attr(rtnl.IFINFOMSG_SIZE)

    if attrs[rtnl.IFLA_IFNAME] then
        local ifname = nl.attr_get_str(attrs[rtnl.IFLA_IFNAME])
        print('ifname:', ifname)
    end

    if attrs[rtnl.IFLA_MTU] then
        local mtu = nl.attr_get_u32(attrs[rtnl.IFLA_MTU])
        print('mtu:', mtu)
    end

    if attrs[rtnl.IFLA_ADDRESS] then
        local addr = nl.attr_get_payload(attrs[rtnl.IFLA_ADDRESS])
        print('addr:', hex.encode(addr, ':'))
    end

    print()
end

local sock, err = nl.open(nl.NETLINK_ROUTE)
if not sock then
    print('open fail:', err)
    return
end

local ok, err = sock:bind(rtnl.RTNLGRP_LINK)
if not ok then
    print('bind fail:', err)
    return
end

ok, err = sock:recv_messages(function(msg, nlh)
    if nlh.type == rtnl.RTM_NEWLINK or nlh.type == rtnl.RTM_DELLINK then
        print_event(nlh, msg)
    end
end)
if not ok then
    print('err:', err)
end
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link_event.lua
