Two questions about lua

[joris dedieu]

Hi all,

I started to drive into haproxy's lua interface. I produced a few code
that allows dnsbl lookup and it seems to work.

First I have a C wrapper against the libc resolver..

#include <netdb.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#include <lua53/lua.h>
#include <lua53/lauxlib.h>

static int gethostbyname_wrapper(lua_State *L)
{
        const char* query = luaL_checkstring(L, 1);
        struct hostent *he;
        if ((he = gethostbyname(query)) != NULL) {
                const char *first_addr =
                    inet_ntoa(*(struct in_addr*)he->h_addr_list[0]);
                lua_pushstring(L, first_addr);
                return 1;
        }
        return 0;
}

static const luaL_Reg sysdb_methods[] = {
        {"gethostbyname", gethostbyname_wrapper},
        {NULL, NULL}
};

LUALIB_API int luaopen_sysdb(lua_State *L) {
        luaL_newlib(L, sysdb_methods);
        return 1;
}

I have some doubts on the asyncness of libc operations but in other
side I don't want to reinvent the wheel. Should I prefer a resolver
implementation that uses lua socket ? As far as I tested libc seems to
do the job.

Then the lua code

local sysdb = require("sysdb")

core.register_fetches("rbl", function(txn, rbl, ip)
        if (not ip) then
                ip = txn.sf:src()
        end
        if (not rbl) then
                rbl = "zen.spamhaus.org"
        end
        local query = rbl
        for x in string.gmatch(ip, "[^%.]+") do
                query = x .. '.' .. query
        end
        if(sysdb.gethostbyname(query)) then
                return 1
        else
                return 0
        end
end)

I want to use a sticky table as a local cache so my second question :
is there a way to set a gpt0 value from lua ?

Thanks for any comments on this.
Joris