Sindbad~EG File Manager

local ffi = require "ffi"
local type = type
local byte = string.byte
local _M = {}

-- FFI stuff from : https://groups.google.com/g/openresty/c/nl3A-Z6ZmWA
-- Also see : https://github.com/agentzh/lua-php-utils

ffi.cdef[[
    struct in_addr {
        uint32_t s_addr;
    };

    int inet_aton(const char *cp, struct in_addr *inp);
    uint32_t ntohl(uint32_t netlong);

    char *inet_ntoa(struct in_addr in);
    uint32_t htonl(uint32_t hostlong);
]]

function _M.ip2long(ip)
    local inp = ffi.new("struct in_addr[1]")
    if ffi.C.inet_aton(ip, inp) ~= 0 then
        return ffi.C.ntohl(inp[0].s_addr)
    end
    return nil
end

function _M.long2ip(long)
    if type(long) ~= "number" then
        return nil
    end
    local addr = ffi.new("struct in_addr")
    addr.s_addr = ffi.C.htonl(long)
    return ffi.string(ffi.C.inet_ntoa(addr))
end

-- Convert a binary nginx IP to a long representation
-- @binaryIp the IP binary representation from ngx.var.binary_remote_addr
function _M.binary2longIp(binaryIp)
    return 16777216 * byte(binaryIp, 1) 
    + 65536 * byte(binaryIp, 2) 
    + 256 * byte(binaryIp, 3) 
    + byte(binaryIp, 4)
end

-- Convert a binary nginx IP to the normal string reprensentation of an IP address
-- @binaryIp the IP binary representation from ngx.var.binary_remote_addr
-- @return string|nil
function _M.binaryToStringIp(binaryIp)
    local longIp = _M.binary2longIp(binaryIp)
    if(type(longIp) ~= 'number') then
        return nil
    end
    return _M.long2ip(longIp)
end

return _M