preloadNSS: Drop the dns query workaround

We can actually just load nss ourselves and call in nss to configure it
and we don't need to run a dummy query entirely to have nss load nss_dns
as a side-effect.

Signed-off-by: Arthur Gautier <baloo@superbaloo.net>
This commit is contained in:
Arthur Gautier 2021-10-13 17:10:35 +00:00
parent 4c0cde95ad
commit d1da45855c

View file

@ -15,9 +15,9 @@
#include <sys/stat.h>
#include <unistd.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <gnu/lib-names.h>
#include <nss.h>
#include <dlfcn.h>
#include <openssl/crypto.h>
@ -121,21 +121,8 @@ static void preloadNSS() {
been loaded in the parent. So we force a lookup of an invalid domain to force the NSS machinery to
load its lookup libraries in the parent before any child gets a chance to. */
std::call_once(dns_resolve_flag, []() {
struct addrinfo *res = NULL;
/* nss will only force the "local" (not through nscd) dns resolution if its on the LOCALDOMAIN.
We need the resolution to be done locally, as nscd socket will not be accessible in the
sandbox. */
char * previous_env = getenv("LOCALDOMAIN");
setenv("LOCALDOMAIN", "invalid", 1);
if (getaddrinfo("this.pre-initializes.the.dns.resolvers.invalid.", "http", NULL, &res) == 0) {
if (res) freeaddrinfo(res);
}
if (previous_env) {
setenv("LOCALDOMAIN", previous_env, 1);
} else {
unsetenv("LOCALDOMAIN");
}
dlopen (LIBNSS_DNS_SO, RTLD_NOW);
__nss_configure_lookup ("hosts", "dns");
});
}