Rewrite byte parsing in full JS without depending on parseInt

The parseInt function is full of surprises. Instead of trying to find all its pitfalls, let's parse bytes manually.

Author: rs

lib/netmask.coffee

@@ -6,27 +6,57 @@ long2ip = (long) ->
  return [a, b, c, d].join('.')
 
 ip2long = (ip) ->
- b = (ip + '').split('.');
- if b.length is 0 or b.length > 4 then throw new Error('Invalid IP')
- for byte, i in b
- if byte and byte[0] == '0'
- if byte.length > 2 and (byte[1] == 'x' or byte[1] == 'x')
- # make sure 0x prefixed bytes are parsed as hex
- byte = parseInt(byte, 16)
- else
- # make sure 0 prefixed bytes are parsed as octal
- byte = parseInt(byte, 8)
- else if byte and (byte[0] == ' ' or byte[byte.length-1] == ' ')
- throw new Error('Invalid IP')
- else
- byte = parseInt(byte, 10)
- if isNaN(byte) then throw new Error("Invalid byte: #{byte}")
- if byte < 0 or byte > 255 then throw new Error("Invalid byte: #{byte}")
- b[i] = byte
+ b = []
+ for i in [0..3]
+ if ip.length == 0
+ break
+ if i > 0
+ if ip[0] != '.'
+ throw new Error('Invalid IP')
+ ip = ip.substring(1)
+ [n, c] = atob(ip)
+ ip = ip.substring(c)
+ b.push(n)
+ if ip.length != 0
+ throw new Error('Invalid IP')
  while b.length < 4
  b.unshift(0)
  return (b[0] << 24 | b[1] << 16 | b[2] << 8 | b[3]) >>> 0
 
+atob = (s) ->
+ n = 0
+ base = 10
+ dmax = '9'
+ i = 0
+ if s.length > 1 and s[i] == '0'
+ if s[i+1] == 'x' or s[i+1] == 'X'
+ i+=2
+ base = 16
+ else if '0' <= s[i+1] and s[i+1] <= '7'
+ i++
+ base = 8
+ dmax = '7'
+ start = i
+ chr = (b) -> return b.charCodeAt(0)
+ while s.length > 0
+ if '0' <= s[i] and s[i] <= dmax
+ n = n*base + (chr(s[i])-chr('0'))
+ else if base == 16
+ if 'a' <= s[i] and s[i] <= 'f'
+ n = n*base + (10+chr(s[i])-chr('a'))
+ else if 'A' <= s[i] and s[i] <= 'F'
+ n = n*base + (10+chr(s[i])-chr('A'))
+ else
+ break
+ else
+ break
+ if n > 0xFF
+ throw new Error('byte overflow')
+ i++
+ if i == start
+ throw new Error('empty octet')
+ return [n, i]
+
 class Netmask
  constructor: (net, mask) ->
  throw new Error("Missing `net' parameter") unless typeof net is 'string'

test/badnets.coffee

@@ -35,11 +35,14 @@ vows.describe('IPs with bytes greater than 255')
 vows.describe('Invalid IP format')
  .addBatch
  ' 1.2.3.4': shouldFailWithError 'Invalid net'
+ ' 1.2.3.4': shouldFailWithError 'Invalid net'
  '1. 2.3.4': shouldFailWithError 'Invalid net'
  '1.2. 3.4': shouldFailWithError 'Invalid net'
  '1.2.3. 4': shouldFailWithError 'Invalid net'
  '1.2.3.4 ': shouldFailWithError 'Invalid net'
  '1 .2.3.4': shouldFailWithError 'Invalid net'
+ '018.0.0.0': shouldFailWithError 'Invalid net'
+ '0xfg.0.0.0': shouldFailWithError 'Invalid net'
  .export(module)
 
 vows.describe('Ranges that are a power-of-two big, but are not legal blocks')