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/* $Id: dnsproc.c,v 1.12 2021/12/13 13:30:39 jca Exp $ */
/*
* Copyright (c) 2016 Kristaps Dzonsons <kristaps@bsd.lv>
*
* 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 AUTHORS DISCLAIM ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF 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/socket.h>
#include <arpa/inet.h>
#include <err.h>
#include <netdb.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "extern.h"
struct addr {
int family; /* 4 for PF_INET, 6 for PF_INET6 */
char ip[INET6_ADDRSTRLEN];
};
/*
* This is a modified version of host_dns in config.c of OpenBSD's ntpd.
*/
/*
* Copyright (c) 2003, 2004 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 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.
*/
static ssize_t
host_dns(const char *s, struct addr *vec)
{
struct addrinfo hints, *res0, *res;
int error;
ssize_t vecsz;
struct sockaddr *sa;
memset(&hints, 0, sizeof(hints));
hints.ai_family = PF_UNSPEC;
hints.ai_socktype = SOCK_DGRAM; /* DUMMY */
hints.ai_flags = AI_ADDRCONFIG;
error = getaddrinfo(s, NULL, &hints, &res0);
if (error == EAI_AGAIN ||
/* FIXME */
#ifndef __FreeBSD__
error == EAI_NODATA ||
#endif
error == EAI_NONAME)
return 0;
if (error) {
warnx("%s: parse error: %s",
s, gai_strerror(error));
return -1;
}
for (vecsz = 0, res = res0;
res != NULL && vecsz < MAX_SERVERS_DNS;
res = res->ai_next) {
if (res->ai_family != AF_INET &&
res->ai_family != AF_INET6)
continue;
sa = res->ai_addr;
if (res->ai_family == AF_INET) {
vec[vecsz].family = 4;
inet_ntop(AF_INET,
&(((struct sockaddr_in *)sa)->sin_addr),
vec[vecsz].ip, INET6_ADDRSTRLEN);
} else {
vec[vecsz].family = 6;
inet_ntop(AF_INET6,
&(((struct sockaddr_in6 *)sa)->sin6_addr),
vec[vecsz].ip, INET6_ADDRSTRLEN);
}
dodbg("%s: DNS: %s", s, vec[vecsz].ip);
vecsz++;
}
freeaddrinfo(res0);
return vecsz;
}
int
dnsproc(int nfd)
{
char *look = NULL, *last = NULL;
struct addr v[MAX_SERVERS_DNS];
int rc = 0, cc;
long lval;
ssize_t vsz = 0;
size_t i;
enum dnsop op;
if (pledge("stdio dns", NULL) == -1) {
warn("pledge");
goto out;
}
/*
* This is simple: just loop on a request operation, and each
* time we write back zero or more entries.
* Also do a simple trick and cache the last lookup.
*/
for (;;) {
op = DNS__MAX;
if ((lval = readop(nfd, COMM_DNS)) == 0)
op = DNS_STOP;
else if (lval == DNS_LOOKUP)
op = lval;
if (op == DNS__MAX) {
warnx("unknown operation from netproc");
goto out;
} else if (op == DNS_STOP)
break;
if ((look = readstr(nfd, COMM_DNSQ)) == NULL)
goto out;
/*
* Check if we're asked to repeat the lookup.
* If not, request it from host_dns().
*/
if (last == NULL || strcmp(look, last)) {
if ((vsz = host_dns(look, v)) < 0)
goto out;
free(last);
last = look;
look = NULL;
} else {
free(look);
look = NULL;
}
if ((cc = writeop(nfd, COMM_DNSLEN, vsz)) == 0)
break;
else if (cc < 0)
goto out;
for (i = 0; i < (size_t)vsz; i++) {
if (writeop(nfd, COMM_DNSF, v[i].family) <= 0)
goto out;
if (writestr(nfd, COMM_DNSA, v[i].ip) <= 0)
goto out;
}
}
rc = 1;
out:
close(nfd);
free(look);
free(last);
return rc;
}
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