alfred/files/bat-hosts.lua

   1 #!/usr/bin/lua
   2
   3 local type_id = 64 -- bat-hosts
   4
   5 function get_hostname()
   6   local hostfile = io.open("/proc/sys/kernel/hostname", "r")
   7   local ret_string = hostfile:read()
   8   hostfile:close()
   9   return ret_string
  10 end
  11
  12 function get_interfaces_names()
  13   local ret = {}
  14
  15   for name in io.popen("ls -1 /sys/class/net/"):lines() do
  16     table.insert(ret, name)
  17   end
  18
  19   return ret
  20 end
  21
  22 function get_interface_address(name)
  23   local addressfile = io.open("/sys/class/net/"..name.."/address", "r")
  24   local ret_string = addressfile:read()
  25   addressfile:close()
  26   return ret_string
  27 end
  28
  29
  30 local function generate_bat_hosts()
  31 -- get hostname and interface macs/names
  32 -- then return a table containing valid bat-hosts lines
  33   local n, i
  34   local ifaces, ret = {}, {}
  35
  36   local hostname = get_hostname()
  37
  38   for n, i in ipairs(get_interfaces_names()) do
  39     local address = get_interface_address(i)
  40     if not ifaces[address] then ifaces[address] = i end
  41   end
  42
  43   for mac, iname in pairs(ifaces) do
  44     if mac:match("^%x%x:%x%x:%x%x:%x%x:%x%x:%x%x$") and not mac:match("00:00:00:00:00:00") then
  45       table.insert(ret, mac.." "..hostname.."_"..iname.."\n")
  46     end
  47   end
  48
  49   return ret
  50 end
  51
  52 local function publish_bat_hosts()
  53 -- pass a raw chunk of data to alfred
  54   local fd = io.popen("alfred -s " .. type_id, "w")
  55   if fd then
  56     local ret = generate_bat_hosts()
  57     if ret then
  58       fd:write(table.concat(ret))
  59     end
  60     fd:close()
  61   end
  62 end
  63
  64 local function write_bat_hosts(rows)
  65   local content = { "### /tmp/bat-hosts generated by alfred-bat-hosts\n",
  66                     "### /!\\ This file is overwritten every 5 minutes /!\\\n",
  67                     "### (To keep manual changes, replace /etc/bat-hosts symlink with a static file)\n" }
  68
  69   -- merge the chunks from all nodes, de-escaping newlines
  70   for _, row in ipairs(rows) do
  71     local node, value = unpack(row)
  72     table.insert(content, "# Node ".. node .. "\n")
  73     table.insert(content, value:gsub("\x0a", "\n") .. "\n")
  74   end
  75
  76   -- write parsed content down to disk
  77   local fd = io.open("/tmp/bat-hosts", "w")
  78   if fd then
  79     fd:write(table.concat(content))
  80     fd:close()
  81   end
  82
  83   -- try to make a symlink in /etc pointing to /tmp,
  84   -- if it exists, ln will do nothing.
  85   os.execute("ln -ns /tmp/bat-hosts /etc/bat-hosts 2>/dev/null")
  86 end
  87
  88 local function receive_bat_hosts()
  89 -- read raw chunks from alfred, convert them to a nested table and call write_bat_hosts
  90   local fd = io.popen("alfred -r " .. type_id)
  91     --[[ this command returns something like
  92     { "54:e6:fc:b9:cb:37", "00:11:22:33:44:55 ham_wlan0\x0a00:22:33:22:33:22 ham_eth0\x0a" },
  93     { "90:f6:52:bb:ec:57", "00:22:33:22:33:23 spam\x0a" },
  94     ]]--
  95
  96   if fd then
  97     local output = fd:read("*a")
  98     if output then
  99       assert(loadstring("rows = {" .. output .. "}"))()
 100       write_bat_hosts(rows)
 101     end
 102     fd:close()
 103   end
 104 end
 105
 106 publish_bat_hosts()
 107 receive_bat_hosts()