* luci/libs: added inline documentation and luci.ip.cidr.sub() to luci.ip; allow CIDR notation _and_ netmask argument in IPv4() and IPv6() constructors

libs/core/luasrc/ip.lua

@@ -14,6 +14,7 @@ $Id$
 
 ]]--
 
+--- LuCI IP calculation library.
 module( "luci.ip", package.seeall )
 
 require("bit")
@@ -30,6 +31,7 @@ local function __bless(x)
 	return setmetatable( x, {
 		__index	= luci.ip.cidr,
 		__add   = luci.ip.cidr.add,
+		__sub   = luci.ip.cidr.sub,
 		__lt	= luci.ip.cidr.lower,
 		__eq	= luci.ip.cidr.equal,
 		__le	=
@@ -54,8 +56,11 @@ local function __length(family)
 	end
 end
 
--- htons(), htonl(), ntohs(), ntohl()
+--- Convert given short value to network byte order on little endian hosts
-
+-- @param x	Unsigned integer value between 0x0000 and 0xFFFF
+-- @return	Byte-swapped value
+-- @see		htonl
+-- @see		ntohs
 function htons(x)
 	if LITTLE_ENDIAN then
 		return bit.bor(
@@ -67,6 +72,11 @@ function htons(x)
 	end
 end
 
+--- Convert given long value to network byte order on little endian hosts
+-- @param x	Unsigned integer value between 0x00000000 and 0xFFFFFFFF
+-- @return	Byte-swapped value
+-- @see		htons
+-- @see		ntohl
 function htonl(x)
 	if LITTLE_ENDIAN then
 		return bit.bor(
@@ -78,10 +88,31 @@ function htonl(x)
 	end
 end
 
+--- Convert given short value to host byte order on little endian hosts
+-- @param x	Unsigned integer value between 0x0000 and 0xFFFF
+-- @return	Byte-swapped value
+-- @see		htonl
+-- @see		ntohs
 ntohs = htons
+
+--- Convert given short value to host byte order on little endian hosts
+-- @param x	Unsigned integer value between 0x00000000 and 0xFFFFFFFF
+-- @return	Byte-swapped value
+-- @see		htons
+-- @see		ntohl
 ntohl = htonl
 
 
+--- Parse given IPv4 address in dotted quad or CIDR notation. If an optional
+-- netmask is given as second argument and the IP address is encoded in CIDR
+-- notation then the netmask parameter takes precedence. If neither a CIDR
+-- encoded prefix nor a netmask parameter is given, then a prefix length of
+-- 32 bit is assumed.
+-- @param address	IPv4 address in dotted quad or CIDR notation
+-- @param netmask	IPv4 netmask in dotted quad notation (optional)
+-- @return			luci.ip.cidr instance or nil if given address was invalid
+-- @see				IPv6
+-- @see				Hex
 function IPv4(address, netmask)
 	address = address or "0.0.0.0/0"
 
@@ -89,11 +120,11 @@ function IPv4(address, netmask)
 
 	local data = {}
 	local prefix = address:match("/(.+)")
+	address = address:gsub("/.+","")
 
 	if netmask then
 		prefix = obj:prefix(netmask)
 	elseif prefix then
-		address = address:gsub("/.+","")
 		prefix = tonumber(prefix)
 		if not prefix or prefix < 0 or prefix > 32 then return nil end
 	else
@@ -119,6 +150,16 @@ function IPv4(address, netmask)
 	end
 end
 
+--- Parse given IPv6 address in full, compressed, mixed or CIDR notation.
+-- If an optional netmask is given as second argument and the IP address is
+-- encoded in CIDR notation then the netmask parameter takes precedence.
+-- If neither a CIDR encoded prefix nor a netmask parameter is given, then a
+-- prefix length of 128 bit is assumed.
+-- @param address	IPv6 address in full/compressed/mixed or CIDR notation
+-- @param netmask	IPv6 netmask in full/compressed/mixed notation (optional)
+-- @return			luci.ip.cidr instance or nil if given address was invalid
+-- @see				IPv4
+-- @see				Hex
 function IPv6(address, netmask)
 	address = address or "::/0"
 
@@ -126,11 +167,11 @@ function IPv6(address, netmask)
 
 	local data = {}
 	local prefix = address:match("/(.+)")
+	address = address:gsub("/.+","")
 
 	if netmask then
 		prefix = obj:prefix(netmask)
 	elseif prefix then
-		address = address:gsub("/.+","")
 		prefix = tonumber(prefix)
 		if not prefix or prefix < 0 or prefix > 128 then return nil end
 	else
@@ -147,7 +188,7 @@ function IPv6(address, netmask)
 		if not borderh then break end
 
 		block = tonumber(address:sub(borderl, borderh - 1), 16)
-		if block and block <= 65535 then
+		if block and block <= 0xFFFF then
 			table.insert(data, block)
 		else
 			if zeroh or borderh - borderl > 1 then return nil end
@@ -160,7 +201,7 @@ function IPv6(address, netmask)
 	chunk = address:sub(borderl)
 	if #chunk > 0 and #chunk <= 4 then
 		block = tonumber(chunk, 16)
-		if not block or block > 65535 then return nil end
+		if not block or block > 0xFFFF then return nil end
 
 		table.insert(data, block)
 	elseif #chunk > 4 then
@@ -198,6 +239,15 @@ function IPv6(address, netmask)
 	end
 end
 
+--- Transform given hex-encoded value to luci.ip.cidr instance of specified
+-- address family.
+-- @param hex		String containing hex encoded value
+-- @param prefix	Prefix length of CIDR instance (optional, default is 32/128)
+-- @param family	Address family, either luci.ip.FAMILY_INET4 or FAMILY_INET6
+-- @param swap		Bool indicating weather to swap byteorder on low endian host
+-- @return			luci.ip.cidr instance or nil if given value was invalid
+-- @see				IPv4
+-- @see				IPv6
 function Hex( hex, prefix, family, swap )
 	family = ( family ~= nil ) and family or FAMILY_INET4
 	swap   = ( swap   == nil ) and true   or swap
@@ -230,16 +280,29 @@ function Hex( hex, prefix, family, swap )
 end
 
 
+--- LuCI IP Library / CIDR instances
+-- @class	module
+-- @name	luci.ip.cidr
 cidr = luci.util.class()
 
+--- Test weather the instance is a IPv4 address.
+-- @return	Boolean indicating a IPv4 address type
+-- @see		is6
 function cidr.is4( self )
 	return self[1] == FAMILY_INET4
 end
 
+--- Test weather the instance is a IPv6 address.
+-- @return	Boolean indicating a IPv6 address type
+-- @see		is4
 function cidr.is6( self )
 	return self[1] == FAMILY_INET6
 end
 
+--- Return a corresponding string representation of the instance.
+-- If the prefix length is lower then the maximum possible prefix length for the
+-- corresponding address type then the address is returned in CIDR notation,
+-- otherwise the prefix will be left out.
 function cidr.string( self )
 	local str
 	if self:is4() then
@@ -260,6 +323,13 @@ function cidr.string( self )
 	return str
 end
 
+--- Test weather the value of the instance is lower then the given address.
+-- This function will throw an exception if the given address has a different
+-- family than this instance.
+-- @param addr	A luci.ip.cidr instance to compare against
+-- @return		Boolean indicating weather this instance is lower
+-- @see			higher
+-- @see			equal
 function cidr.lower( self, addr )
 	assert( self[1] == addr[1], "Can't compare IPv4 and IPv6 addresses" )
 	for i = 1, #self[2] do
@@ -270,6 +340,13 @@ function cidr.lower( self, addr )
 	return false
 end
 
+--- Test weather the value of the instance is higher then the given address.
+-- This function will throw an exception if the given address has a different
+-- family than this instance.
+-- @param addr	A luci.ip.cidr instance to compare against
+-- @return		Boolean indicating weather this instance is higher
+-- @see			lower
+-- @see			equal
 function cidr.higher( self, addr )
 	assert( self[1] == addr[1], "Can't compare IPv4 and IPv6 addresses" )
 	for i = 1, #self[2] do
@@ -280,6 +357,13 @@ function cidr.higher( self, addr )
 	return false
 end
 
+--- Test weather the value of the instance is uequal to the given address.
+-- This function will throw an exception if the given address is a different
+-- family than this instance.
+-- @param addr	A luci.ip.cidr instance to compare against
+-- @return		Boolean indicating weather this instance is equal
+-- @see			lower
+-- @see			higher
 function cidr.equal( self, addr )
 	assert( self[1] == addr[1], "Can't compare IPv4 and IPv6 addresses" )
 	for i = 1, #self[2] do
@@ -290,6 +374,8 @@ function cidr.equal( self, addr )
 	return true
 end
 
+--- Return the prefix length of this CIDR instance.
+-- @return	Prefix length in bit
 function cidr.prefix( self, mask )
 	local prefix = self[3]
 
@@ -322,6 +408,12 @@ function cidr.prefix( self, mask )
 	return prefix
 end
 
+--- Return a corresponding CIDR representing the network address of this
+-- instance.
+-- @param bits	Override prefix length of this instance (optional)
+-- @return		CIDR instance containing the network address
+-- @see			host
+-- @see			mask
 function cidr.network( self, bits )
 	local data = { }
 	bits = bits or self[3]
@@ -341,10 +433,20 @@ function cidr.network( self, bits )
 	return __bless({ self[1], data, __length(self[1]) })
 end
 
+--- Return a corresponding CIDR representing the host address of this
+-- instance. This is intended to extract the host address from larger subnet.
+-- @return		CIDR instance containing the network address
+-- @see			network
+-- @see			mask
 function cidr.host( self )
 	return __bless({ self[1], data, __length(self[1]) })
 end
 
+--- Return a corresponding CIDR representing the netmask of this instance.
+-- @param bits	Override prefix length of this instance (optional)
+-- @return		CIDR instance containing the netmask
+-- @see			network
+-- @see			host
 function cidr.mask( self, bits )
 	local data = { }
 	bits = bits or self[3]
@@ -364,6 +466,9 @@ function cidr.mask( self, bits )
 	return __bless({ self[1], data, __length(self[1]) })
 end
 
+--- Test weather this instance fully contains the given CIDR instance.
+-- @param addr	CIDR instance to test against
+-- @return		Boolean indicating weather this instance contains the given CIDR
 function cidr.contains( self, addr )
 	assert( self[1] == addr[1], "Can't compare IPv4 and IPv6 addresses" )
 
@@ -374,6 +479,10 @@ function cidr.contains( self, addr )
 	return false
 end
 
+--- Add specified amount of hosts to this instance.
+-- @param amount	Number of hosts to add to this instance
+-- @return			CIDR representing the new address or nil on overflow error
+-- @see				sub
 function cidr.add( self, amount )
 	local shorts = { bit.rshift(amount, 16), bit.band(amount, 0xFFFF) }
 	local data   = { unpack(self[2]) }
@@ -394,3 +503,28 @@ function cidr.add( self, amount )
 
 	return __bless({ self[1], data, self[3] })
 end
+
+--- Substract specified amount of hosts from this instance.
+-- @param amount	Number of hosts to substract from this instance
+-- @return			CIDR representing the new address or nil on underflow error
+-- @see				add
+function cidr.sub( self, amount )
+	local shorts = { bit.rshift(amount, 16), bit.band(amount, 0xFFFF) }
+	local data   = { unpack(self[2]) }
+
+	for pos = #data, 1, -1 do
+		local sub = ( #shorts > 0 ) and table.remove( shorts, #shorts ) or 0
+		if ( data[pos] - sub ) < 0 then
+			data[pos] = ( sub - data[pos] ) % 0xFFFF
+			if pos > 1 then
+				data[pos-1] = data[pos-1] - ( sub + data[pos] )
+			else
+				return nil
+			end
+		else
+			data[pos] = data[pos] - sub
+		end
+	end
+
+	return __bless({ self[1], data, self[3] })
+end