Module:IPAddress

Functions are not "local", so other modules can require this module and call them directly. We return an object with 3 small stub functions to call the real ones so that the functions can be called from templates also.

Only dotted decimal notation for IPv4 supported. Does not support dotted hexadecimal, dotted octal, or single-number formats (see IPv4#Address_representations).

Unit tests at Module:IPAddress/testcases

---

--[[
Functions are not "local", so other modules can require this module and call them directly.
We return an object with 3 small stub functions to call the real ones so that the functions
can be called from templates also.

Unit tests at Module:IPAddress/tests
]]

function _isIpV6( s )
    local dcolon, groups
    if type( s ) ~= "string"
        or s:len() == 0
        or s:find( "[^:%x]" ) -- only colon and hex digits are legal chars
        or s:find( "^:[^:]" ) -- can begin or end with :: but not with single :
        or s:find( "[^:]:$" )
        or s:find( ":::" )
    then
        return false
    end 
    s, dcolon = s:gsub( "::", ":" )
    if dcolon > 1 then return false end -- at most one ::
    s = s:gsub( "^:?", ":" ) -- prepend : if needed, upper
    s, groups = s:gsub( ":%x%x?%x?%x?", "" ) -- remove valid groups, and count them
    return ( ( dcolon == 1 and groups < 8 ) or ( dcolon == 0 and groups == 8 ) )
        and ( s:len() == 0 or ( dcolon == 1 and s == ":" ) ) -- might be one dangling : if original ended with ::
end

-- Currently supports only [[dotted decimal]] notation for IPv4. Does not support
-- dotted hexadecimal, dotted octal, or single-number formats (see [[IPv4#Address_representations]]).
function _isIpV4( s )
    local function legal( n ) return ( tonumber( n ) or 256 ) < 256  end-- in lua 0 is true!
    
    if type( s ) ~= "string" then return false end
    local p1, p2, p3, p4 = s:match( "^(%d+)%.(%d+)%.(%d+)%.(%d+)$" ) 
    return legal( p1 ) and legal( p2 ) and legal( p3 ) and legal( p4 )
end

function _isIp( s )
    return _isIpV4( s ) and "4" or _isIpV6( s ) and "6"
end

local p = {}

function p.isIpV6(frame) return _isIpV6( frame.args[ 1 ] ) and "1" or "0" end
function p.isIpV4(frame) return _isIpV4( frame.args[ 1 ] ) and "1" or "0" end
function p.isIp(frame) return _isIp( frame.args[ 1 ] ) or "" end

return p