Add support for system configuration (WIP)

scripts/lua/modules/ipv4_utils.lua

@@ -0,0 +1,196 @@
+--
+-- (C) 2017-20 - ntop.org
+--
+
+local ipv4_utils = {}
+
+local function ip_to_bit(ip)
+  local x = 0
+  local parts = string.split(ip, "%.")
+
+  for i=0,3 do
+    x = (x | (tonumber(parts[i+1]) << ((3-i)*8)))
+  end
+
+  return x
+end
+
+local function bit_to_ip(bits)
+  local parts = {}
+
+  for i=0, 3 do
+    parts[i+1] = ((bits >> ((3-i)*8)) & 0xFF)
+  end
+
+  return table.concat(parts, ".")
+end
+
+--
+-- Get the number of bits allocated for the network specified by the ip netmask
+-- nil is returned on error
+function ipv4_utils.netmask(ip)
+  if not ipv4_utils.valid(ip) then
+    -- bad netmask
+    return nil
+  end
+
+  local parts = string.split(ip, "%.")
+  local netmask = 0
+
+  for i=1,4 do
+    local val = tonumber(parts[i])
+    local x = nil
+
+    if val == 255 then x = 8
+    elseif val == 254 then x = 7
+    elseif val == 252 then x = 6
+    elseif val == 248 then x = 5
+    elseif val == 240 then x = 4
+    elseif val == 224 then x = 3
+    elseif val == 192 then x = 2
+    elseif val == 128 then x = 1
+    elseif val == 0 then x = 0
+    end
+
+    if x == nil then
+      -- bad netmask
+      return nil
+    end
+
+    netmask = netmask + x
+
+    if val ~= 255 then
+      for j=i+1,4 do
+        if tonumber(parts[j]) ~= 0 then
+          -- bad netmask
+          return nil
+        end
+      end
+
+      break
+    end
+  end
+
+  return netmask
+end
+
+function ipv4_utils.cidr_2_addr(cidr)
+  local parts = split(cidr, "/")
+
+  if #parts ~= 2 then
+    return nil
+  end
+
+  local addr = parts[1]
+  local num_netmask = tonumber(parts[2])
+  local netmask = 0x100000000 - (1 << (32-num_netmask))
+
+  return addr, bit_to_ip(netmask)
+end
+
+--
+-- Compares IPv4 addresses
+-- Precondition: a and b are valid ipv4 addresses
+-- Returns:
+--    >0 if a > b
+--    <0 if a < b
+--    0 if a == b
+--
+function ipv4_utils.cmp(a, b)
+   local a_parts = string.split(a, "%.")
+   local b_parts = string.split(b, "%.")
+
+   for i=1,4 do
+      local a_part = tonumber(a_parts[i])
+      local b_part = tonumber(b_parts[i])
+
+      if a_part > b_part then
+         return 1
+      elseif a_part < b_part then
+         return -1
+      end
+   end
+
+   return 0
+end
+
+-- Assumption: 32bit integer are used. This is already assumed by http://bitop.luajit.org/semantics.html
+function ipv4_utils.ipToInt(ip)
+  local intrepr = 0
+
+  for byte in string.gmatch(ip, "%d+") do
+    intrepr = intrepr * 256 + byte
+  end
+
+  return intrepr
+end
+
+function ipv4_utils.intToIp(int)
+  local parts = {
+    ((int >> 24) & 0xFF),
+    ((int >> 16) & 0xFF),
+    ((int >> 8) & 0xFF),
+    (int & 0xFF)
+  }
+
+  return table.concat(parts, ".")
+end
+
+-- Returns possible DHCP range
+function ipv4_utils.get_possible_dhcp_range(ip, network, broadcast_addr)
+  local ip_int = ipv4_utils.ipToInt(ip)
+  local broadcast_int = ipv4_utils.ipToInt(broadcast_addr)
+  local first_ip
+  local last_ip
+
+  if ip_int >= broadcast_int - 1 then
+    first_ip = ipv4_utils.ipToInt(network) + 1
+    last_ip = ip_int - 1
+  else
+    first_ip = ip_int + 1
+    last_ip = broadcast_int - 1
+  end
+
+  return {
+    first_ip = ipv4_utils.intToIp(first_ip),
+    last_ip = ipv4_utils.intToIp(last_ip),
+  }
+end
+
+function ipv4_utils.includes(network, netmask, ip)
+  local lower = network
+  local upper = ipv4_utils.broadcast_address(network, netmask)
+
+  return (ipv4_utils.cmp(ip, lower) > 0) and
+        (ipv4_utils.cmp(ip, upper) < 0)
+end
+
+-- Get the broadcast address for the given netmask
+function ipv4_utils.broadcast_address(ip, netmask)
+  local ipbit = ip_to_bit(ip)
+  local maskbit = ip_to_bit(netmask)
+
+  return bit_to_ip((~(maskbit) | ipbit))
+end
+
+-- https://stackoverflow.com/questions/10975935/lua-function-check-if-ipv4-or-ipv6-or-string
+function ipv4_utils.valid(address)
+   local chunks = {address:match("(%d+)%.(%d+)%.(%d+)%.(%d+)$")}
+
+  if #chunks == 4 then
+    for _, v in pairs(chunks) do
+      if (tonumber(v) < 0) or (tonumber(v) > 255) then
+        return false
+      end
+    end
+
+    return true
+  end
+end
+
+function ipv4_utils.addressToNetwork(address, netmask)
+  local mask = ipv4_utils.netmask(netmask)
+  return ntop.networkPrefix(address, mask) .. "/" .. mask
+end
+
+return ipv4_utils