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/* $OpenBSD: ypldap_dns.c,v 1.20 2024/11/21 13:21:34 claudio Exp $ */
/*
* Copyright (c) 2003-2008 Henning Brauer <henning@openbsd.org>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF MIND, USE, DATA OR PROFITS, WHETHER
* IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
* OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/tree.h>
#include <sys/queue.h>
#include <netinet/in.h>
#include <netdb.h>
#include <pwd.h>
#include <errno.h>
#include <event.h>
#include <resolv.h>
#include <poll.h>
#include <signal.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <limits.h>
#include "ypldap.h"
#include "log.h"
volatile sig_atomic_t quit_dns = 0;
struct imsgev *iev_dns;
void dns_dispatch_imsg(int, short, void *);
void dns_sig_handler(int, short, void *);
void dns_shutdown(void);
int host_dns(const char *, struct ypldap_addr_list *);
void
dns_sig_handler(int sig, short event, void *p)
{
switch (sig) {
case SIGINT:
case SIGTERM:
dns_shutdown();
break;
case SIGHUP:
/* ignore */
break;
default:
fatalx("unexpected signal");
}
}
void
dns_shutdown(void)
{
log_info("dns engine exiting");
_exit(0);
}
pid_t
ypldap_dns(int pipe_ntp[2], struct passwd *pw)
{
pid_t pid;
struct event ev_sigint;
struct event ev_sigterm;
struct event ev_sighup;
struct env env;
switch (pid = fork()) {
case -1:
fatal("cannot fork");
break;
case 0:
break;
default:
return (pid);
}
setproctitle("dns engine");
close(pipe_ntp[0]);
if (setgroups(1, &pw->pw_gid) ||
setresgid(pw->pw_gid, pw->pw_gid, pw->pw_gid) ||
setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid))
fatal("can't drop privileges");
endservent();
if (pledge("stdio dns", NULL) == -1)
fatal("pledge");
event_init();
signal_set(&ev_sigint, SIGINT, dns_sig_handler, NULL);
signal_set(&ev_sigterm, SIGTERM, dns_sig_handler, NULL);
signal_set(&ev_sighup, SIGHUP, dns_sig_handler, NULL);
signal_add(&ev_sigint, NULL);
signal_add(&ev_sigterm, NULL);
signal_add(&ev_sighup, NULL);
if ((env.sc_iev = calloc(1, sizeof(*env.sc_iev))) == NULL)
fatal(NULL);
env.sc_iev->events = EV_READ;
env.sc_iev->data = &env;
imsgbuf_init(&env.sc_iev->ibuf, pipe_ntp[1]);
env.sc_iev->handler = dns_dispatch_imsg;
event_set(&env.sc_iev->ev, env.sc_iev->ibuf.fd, env.sc_iev->events,
env.sc_iev->handler, &env);
event_add(&env.sc_iev->ev, NULL);
event_dispatch();
dns_shutdown();
return (0);
}
void
dns_dispatch_imsg(int fd, short events, void *p)
{
struct imsg imsg;
int n, cnt;
char *name;
struct ypldap_addr_list hn = TAILQ_HEAD_INITIALIZER(hn);
struct ypldap_addr *h;
struct ibuf *buf;
struct env *env = p;
struct imsgev *iev = env->sc_iev;
struct imsgbuf *ibuf = &iev->ibuf;
int shut = 0;
size_t len;
if ((events & (EV_READ | EV_WRITE)) == 0)
fatalx("unknown event");
if (events & EV_READ) {
if ((n = imsgbuf_read(ibuf)) == -1)
fatal("imsgbuf_read error");
if (n == 0)
shut = 1;
}
if (events & EV_WRITE) {
if (imsgbuf_write(ibuf) == -1) {
if (errno == EPIPE) /* connection closed */
shut = 1;
else
fatal("imsgbuf_write");
}
}
for (;;) {
if ((n = imsg_get(ibuf, &imsg)) == -1)
fatal("client_dispatch_imsg: imsg_get error");
if (n == 0)
break;
switch (imsg.hdr.type) {
case IMSG_HOST_DNS:
name = imsg.data;
if (imsg.hdr.len < 1 + IMSG_HEADER_SIZE)
fatalx("invalid IMSG_HOST_DNS received");
len = imsg.hdr.len - 1 - IMSG_HEADER_SIZE;
if (name[len] != '\0' ||
strlen(name) != len)
fatalx("invalid IMSG_HOST_DNS received");
if ((cnt = host_dns(name, &hn)) == -1)
break;
buf = imsg_create(ibuf, IMSG_HOST_DNS,
imsg.hdr.peerid, 0,
cnt * sizeof(struct sockaddr_storage));
if (buf == NULL)
break;
if (cnt > 0) {
while (!TAILQ_EMPTY(&hn)) {
h = TAILQ_FIRST(&hn);
TAILQ_REMOVE(&hn, h, next);
imsg_add(buf, &h->ss, sizeof(h->ss));
free(h);
}
}
imsg_close(ibuf, buf);
break;
default:
break;
}
imsg_free(&imsg);
}
if (!shut)
imsg_event_add(iev);
else {
/* this pipe is dead, so remove the event handler */
event_del(&iev->ev);
event_loopexit(NULL);
}
}
int
host_dns(const char *s, struct ypldap_addr_list *hn)
{
struct addrinfo hints, *res0, *res;
int error, cnt = 0;
struct sockaddr_in *sa_in;
struct sockaddr_in6 *sa_in6;
struct ypldap_addr *h;
memset(&hints, 0, sizeof(hints));
hints.ai_family = PF_UNSPEC;
hints.ai_socktype = SOCK_DGRAM; /* DUMMY */
error = getaddrinfo(s, NULL, &hints, &res0);
if (error != 0) {
log_warnx("could not resolve \"%s\": %s", s,
gai_strerror(error));
if (error == EAI_AGAIN || error == EAI_NODATA ||
error == EAI_NONAME)
return (0);
return (-1);
}
for (res = res0; res && cnt < MAX_SERVERS_DNS; res = res->ai_next) {
if (res->ai_family != AF_INET &&
res->ai_family != AF_INET6)
continue;
if ((h = calloc(1, sizeof(struct ypldap_addr))) == NULL)
fatal(NULL);
h->ss.ss_family = res->ai_family;
if (res->ai_family == AF_INET) {
sa_in = (struct sockaddr_in *)&h->ss;
sa_in->sin_len = sizeof(struct sockaddr_in);
sa_in->sin_addr.s_addr = ((struct sockaddr_in *)
res->ai_addr)->sin_addr.s_addr;
} else {
sa_in6 = (struct sockaddr_in6 *)&h->ss;
sa_in6->sin6_len = sizeof(struct sockaddr_in6);
memcpy(&sa_in6->sin6_addr, &((struct sockaddr_in6 *)
res->ai_addr)->sin6_addr, sizeof(struct in6_addr));
}
TAILQ_INSERT_HEAD(hn, h, next);
cnt++;
}
freeaddrinfo(res0);
return (cnt);
}
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