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 a table with 3 small stub functions to call the "real" ones, in a scribunto fashion,
so the functions can be called from templates also.
]]

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

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

-- return a table to allow the functions to be called from templates
return {
    ["isIpV6"] = function( frame ) return isIpV6( frame.args[ 1 ] ) and "1" or "0" end,
    ["isIpV4"] = function( frame ) return isIpV4( frame.args[ 1 ] ) and "1" or "0" end,
    ["isIp"] = function( frame ) return isIp( frame.args[ 1 ] ) or "" end
}