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.

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')