fix: Handling ip addresses in format of ::ffff:192.168.0.1

[John222]

In case the haproxy is running in Ipv4 and IPv6 mode, the haproxy maps Ipv4 addresses in the IPv6 format. This fix converts the IPv4 mapped address in IPv6 format back to a regular IPv4 address like 192.168.0.1

[superstes]

@John222 Yeah - makes total sense.
Do you mind trying a non-regex alternative? It might perform marginally better

local V4_MAPPED_PREFIX = "::ffff:"
local PREFIX_LEN = 7

local function normalize_ip(ip)
    if ip:sub(1, PREFIX_LEN) == V4_MAPPED_PREFIX then
        return ip:sub(PREFIX_LEN + 1)
    end
    return ip
end

In my tests it worked

[John222]

Hi @superstes i tried your suggestion. It worked.