[B.A.T.M.A.N.] [PATCH 2/2] alfred: Bundle a lua script for autogenerating bat-hosts file

[Gui Iribarren <gui@altermundi.net>]

Provide a lua script that uses alfred to propagate and collect all interface
mac + names, then generate a /tmp/bat-hosts file.
If there's already a (probably hand-made) /etc/bat-hosts it won't overwrite it
but if there's none, it will symlink /etc/bat-hosts -> /tmp/bat-hosts

Signed-off-by: Gui Iribarren <gui@altermundi.net>
Thanks-to: Joshua Head <joshua.head@outlook.com>
---
 alfred/Makefile            |    2 +
 alfred/files/bat-hosts.lua |  107 ++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 109 insertions(+)
 create mode 100644 alfred/files/bat-hosts.lua

diff --git a/alfred/Makefile b/alfred/Makefile
index db9c71f..7027192 100644
--- a/alfred/Makefile
+++ b/alfred/Makefile
@@ -74,6 +74,8 @@ define Package/alfred/install
 	$(INSTALL_BIN) ./files/alfred.init $(1)/etc/init.d/alfred
 	$(INSTALL_DIR) $(1)/etc/config
 	$(INSTALL_DATA) ./files/alfred.config $(1)/etc/config/alfred
+	$(INSTALL_DIR) $(1)/etc/alfred
+	$(INSTALL_BIN) ./files/bat-hosts.lua $(1)/etc/alfred/bat-hosts.lua
 endef
 
 $(eval $(call BuildPackage,alfred))
diff --git a/alfred/files/bat-hosts.lua b/alfred/files/bat-hosts.lua
new file mode 100644
index 0000000..19f2cad
--- /dev/null
+++ b/alfred/files/bat-hosts.lua
@@ -0,0 +1,107 @@
+#!/usr/bin/lua
+
+local type_id = 64 -- bat-hosts
+
+function get_hostname()
+  local hostfile = io.open("/proc/sys/kernel/hostname", "r")
+  local ret_string = hostfile:read("*a")
+  ret_string = string.gsub(ret_string, "\n", "")
+  hostfile:close()
+  return ret_string
+end
+
+function get_interfaces_names()
+  local ret = {}
+
+  for name in io.popen("ls -1 /sys/class/net/"):lines() do
+    table.insert(ret, name)
+  end
+
+  return ret
+end
+
+function get_interface_address(name)
+  local addressfile = io.open("/sys/class/net/"..name.."/address", "r")
+  local ret_string = addressfile:read("*a")
+  ret_string = string.gsub(ret_string, "\n", "")
+  addressfile:close()
+  return ret_string
+end
+
+
+local function generate_bat_hosts()
+-- get hostname and interface macs/names
+-- then return a table containing valid bat-hosts lines
+  local n, i
+  local ifaces, ret = {}, {}
+
+  local hostname = get_hostname()
+
+  for n, i in ipairs(get_interfaces_names()) do
+    local address = get_interface_address(i)
+    ifaces[address] = i
+  end
+
+  for mac, iname in pairs(ifaces) do
+    if mac:match("^%x%x:%x%x:%x%x:%x%x:%x%x:%x%x$") and not mac:match("00:00:00:00:00:00") then
+      table.insert(ret, mac.." "..hostname.."_"..iname.."\n")
+    end
+  end
+
+  return ret
+end
+
+local function publish_bat_hosts()
+-- pass a raw chunk of data to alfred
+  local fd = io.popen("alfred -s " .. type_id, "w")
+  if fd then
+    local ret = generate_bat_hosts()
+    if ret then
+      fd:write(table.concat(ret))
+    end
+    fd:close()
+  end
+end
+
+local function receive_bat_hosts()
+-- read raw chunks from alfred, convert them to a nested table and call write_bat_hosts
+  local fd = io.popen("alfred -r " .. type_id)
+    --[[ this command returns something like
+    { "54:e6:fc:b9:cb:37", "00:11:22:33:44:55 ham_wlan0\x0a00:22:33:22:33:22 ham_eth0\x0a" },
+    { "90:f6:52:bb:ec:57", "00:22:33:22:33:23 spam\x0a" },
+    ]]--
+
+  if fd then
+    local output = fd:read("*a")
+    if output then
+      assert(loadstring("rows = {" .. output .. "}"))()
+      write_bat_hosts(rows)
+    end
+    fd:close()
+  end
+end
+
+local function write_bat_hosts(rows)
+  local content = { "### File generated by alfred-bat-hosts\n" }
+
+  -- merge the chunks from all nodes, de-escaping newlines
+  for _, row in ipairs(rows) do
+    local node, value = unpack(row)
+    table.insert(content, "# Node ".. node .. "\n")
+    table.insert(content, value:gsub("\x0a", "\n") .. "\n")
+  end
+
+  -- write parsed content down to disk
+  local fd = io.open("/tmp/bat-hosts", "w")
+  if fd then
+    fd:write(table.concat(content))
+    fd:close()
+  end
+
+  -- try to make a symlink in /etc pointing to /tmp,
+  -- if it exists, ln will do nothing.
+  os.execute("ln -ns /tmp/bat-hosts /etc/bat-hosts 2>/dev/null")
+end
+
+publish_bat_hosts()
+receive_bat_hosts()
-- 
1.7.10.4