static int forward_query(int udpfd, union mysockaddr *udpaddr,
struct all_addr *dst_addr, unsigned int dst_iface,
HEADER *header, size_t plen, time_t now, struct frec *forward)
{
char *domain = NULL;
int type = 0;
struct all_addr *addrp = NULL;
unsigned int crc = questions_crc(header, plen, daemon->namebuff);
unsigned short flags = 0;
unsigned short gotname = extract_request(header, plen, daemon->namebuff, NULL);
struct server *start = NULL;
/* may be no servers available. */
if (!daemon->servers)
forward = NULL;
else if (forward || (forward = lookup_frec_by_sender(ntohs(header->id), udpaddr, crc)))
{
/* retry on existing query, send to all available servers */
domain = forward->sentto->domain;
forward->sentto->failed_queries++;
if (!(daemon->options & OPT_ORDER))
{
forward->forwardall = 1;
daemon->last_server = NULL;
}
type = forward->sentto->flags & SERV_TYPE;
if (!(start = forward->sentto->next))
start = daemon->servers; /* at end of list, recycle */
header->id = htons(forward->new_id);
}
else
{
if (gotname)
flags = search_servers(now, &addrp, gotname, daemon->namebuff, &type, &domain);
if (!flags && !(forward = get_new_frec(now, NULL)))
/* table full - server failure. */
flags = F_NEG;
if (forward)
{
/* force unchanging id for signed packets */
int is_sign;
find_pseudoheader(header, plen, NULL, NULL, &is_sign);
forward->source = *udpaddr;
forward->dest = *dst_addr;
forward->iface = dst_iface;
forward->orig_id = ntohs(header->id);
forward->new_id = get_id(is_sign, forward->orig_id, crc);
forward->fd = udpfd;
forward->crc = crc;
forward->forwardall = 0;
header->id = htons(forward->new_id);
/* In strict_order mode, or when using domain specific servers
always try servers in the order specified in resolv.conf,
otherwise, use the one last known to work. */
if (type != 0 || (daemon->options & OPT_ORDER))
start = daemon->servers;
else if (!(start = daemon->last_server) ||
daemon->forwardcount++ > FORWARD_TEST ||
difftime(now, daemon->forwardtime) > FORWARD_TIME)
{
start = daemon->servers;
forward->forwardall = 1;
daemon->forwardcount = 0;
daemon->forwardtime = now;
}
}
}
/* check for send errors here (no route to host)
if we fail to send to all nameservers, send back an error
packet straight away (helps modem users when offline) */
if (!flags && forward)
{
struct server *firstsentto = start;
int forwarded = 0;
while (1)
{
/* only send to servers dealing with our domain.
domain may be NULL, in which case server->domain
must be NULL also. */
if (type == (start->flags & SERV_TYPE) &&
(type != SERV_HAS_DOMAIN || hostname_isequal(domain, start->domain)) &&
!(start->flags & SERV_LITERAL_ADDRESS))
{
int fd;
/* find server socket to use, may need to get random one. */
if (start->sfd)
fd = start->sfd->fd;
else
{
#ifdef HAVE_IPV6
if (start->addr.sa.sa_family == AF_INET6)
{
if (!forward->rfd6 &&
!(forward->rfd6 = allocate_rfd(AF_INET6)))
break;
daemon->rfd_save = forward->rfd6;
fd = forward->rfd6->fd;
}
else
#endif
{
if (!forward->rfd4 &&
!(forward->rfd4 = allocate_rfd(AF_INET)))
break;
daemon->rfd_save = forward->rfd4;
fd = forward->rfd4->fd;
}
#ifdef ANDROID
// Mark the socket so it goes out on the correct network. Note
// that we never clear the mark, only re-set it the next time we
// allocate a new random fd. This is because we buffer DNS
// queries (in daemon->srv_save, daemon->packet_len) and socket
// file descriptors (in daemon->rfd_save) with the expectation of
// being able to use them again.
//
// Server fds are marked separately in allocate_sfd.
setsockopt(fd, SOL_SOCKET, SO_MARK, &start->mark, sizeof(start->mark));
#endif
}
if (sendto(fd, (char *)header, plen, 0,
&start->addr.sa,
sa_len(&start->addr)) == -1)
{
if (retry_send())
continue;
}
else
{
/* Keep info in case we want to re-send this packet */
daemon->srv_save = start;
daemon->packet_len = plen;
if (!gotname)
strcpy(daemon->namebuff, "query");
if (start->addr.sa.sa_family == AF_INET)
log_query(F_SERVER | F_IPV4 | F_FORWARD, daemon->namebuff,
(struct all_addr *)&start->addr.in.sin_addr, NULL);
#ifdef HAVE_IPV6
else
log_query(F_SERVER | F_IPV6 | F_FORWARD, daemon->namebuff,
(struct all_addr *)&start->addr.in6.sin6_addr, NULL);
#endif
start->queries++;
forwarded = 1;
forward->sentto = start;
if (!forward->forwardall)
break;
forward->forwardall++;
}
}
if (!(start = start->next))
start = daemon->servers;
if (start == firstsentto)
break;
}
if (forwarded)
return 1;
/* could not send on, prepare to return */
header->id = htons(forward->orig_id);
free_frec(forward); /* cancel */
}
/* could not send on, return empty answer or address if known for whole domain */
if (udpfd != -1)
{
plen = setup_reply(header, plen, addrp, flags, daemon->local_ttl);
send_from(udpfd, daemon->options & OPT_NOWILD, (char *)header, plen, udpaddr, dst_addr, dst_iface);
}
return 0;
}
static int forward_query(int udpfd, union mysockaddr *udpaddr,
struct all_addr *dst_addr, unsigned int dst_iface,
struct dns_header *header, size_t plen, time_t now, struct frec *forward)
{
char *domain = NULL;
int type = 0, norebind = 0;
struct all_addr *addrp = NULL;
unsigned int crc = questions_crc(header, plen, daemon->namebuff);
unsigned int flags = 0;
unsigned int gotname = extract_request(header, plen, daemon->namebuff, NULL);
struct server *start = NULL;
/* RFC 4035: sect 4.6 para 2 */
header->hb4 &= ~HB4_AD;
/* may be no servers available. */
if (!daemon->servers)
forward = NULL;
else if (forward || (forward = lookup_frec_by_sender(ntohs(header->id), udpaddr, crc)))
{
/* retry on existing query, send to all available servers */
domain = forward->sentto->domain;
forward->sentto->failed_queries++;
if (!option_bool(OPT_ORDER))
{
forward->forwardall = 1;
daemon->last_server = NULL;
}
type = forward->sentto->flags & SERV_TYPE;
if (!(start = forward->sentto->next))
start = daemon->servers; /* at end of list, recycle */
header->id = htons(forward->new_id);
}
else
{
if (gotname)
flags = search_servers(now, &addrp, gotname, daemon->namebuff, &type, &domain, &norebind);
if (!flags && !(forward = get_new_frec(now, NULL)))
/* table full - server failure. */
flags = F_NEG;
if (forward)
{
forward->source = *udpaddr;
forward->dest = *dst_addr;
forward->iface = dst_iface;
forward->orig_id = ntohs(header->id);
forward->new_id = get_id(crc);
forward->fd = udpfd;
forward->crc = crc;
forward->forwardall = 0;
if (norebind)
forward->flags |= FREC_NOREBIND;
if (header->hb4 & HB4_CD)
forward->flags |= FREC_CHECKING_DISABLED;
header->id = htons(forward->new_id);
/* In strict_order mode, always try servers in the order
specified in resolv.conf, if a domain is given
always try all the available servers,
otherwise, use the one last known to work. */
if (type == 0)
{
if (option_bool(OPT_ORDER))
start = daemon->servers;
else if (!(start = daemon->last_server) ||
daemon->forwardcount++ > FORWARD_TEST ||
difftime(now, daemon->forwardtime) > FORWARD_TIME)
{
start = daemon->servers;
forward->forwardall = 1;
daemon->forwardcount = 0;
daemon->forwardtime = now;
}
}
else
{
start = daemon->servers;
if (!option_bool(OPT_ORDER))
forward->forwardall = 1;
}
}
}
/* check for send errors here (no route to host)
if we fail to send to all nameservers, send back an error
packet straight away (helps modem users when offline) */
if (!flags && forward)
{
struct server *firstsentto = start;
int forwarded = 0;
if (udpaddr && option_bool(OPT_ADD_MAC))
plen = add_mac(header, plen, ((char *) header) + PACKETSZ, udpaddr);
while (1)
{
/* only send to servers dealing with our domain.
domain may be NULL, in which case server->domain
must be NULL also. */
if (type == (start->flags & SERV_TYPE) &&
(type != SERV_HAS_DOMAIN || hostname_isequal(domain, start->domain)) &&
!(start->flags & SERV_LITERAL_ADDRESS))
{
int fd;
/* find server socket to use, may need to get random one. */
if (start->sfd)
fd = start->sfd->fd;
else
{
#ifdef HAVE_IPV6
if (start->addr.sa.sa_family == AF_INET6)
{
if (!forward->rfd6 &&
!(forward->rfd6 = allocate_rfd(AF_INET6)))
break;
daemon->rfd_save = forward->rfd6;
fd = forward->rfd6->fd;
}
else
#endif
{
if (!forward->rfd4 &&
!(forward->rfd4 = allocate_rfd(AF_INET)))
break;
daemon->rfd_save = forward->rfd4;
fd = forward->rfd4->fd;
}
#ifdef HAVE_CONNTRACK
/* Copy connection mark of incoming query to outgoing connection. */
if (option_bool(OPT_CONNTRACK))
{
unsigned int mark;
if (get_incoming_mark(udpaddr, dst_addr, 0, &mark))
setsockopt(fd, SOL_SOCKET, SO_MARK, &mark, sizeof(unsigned int));
}
#endif
}
if (sendto(fd, (char *)header, plen, 0,
&start->addr.sa,
sa_len(&start->addr)) == -1)
{
if (retry_send())
continue;
}
else
{
/* Keep info in case we want to re-send this packet */
daemon->srv_save = start;
daemon->packet_len = plen;
if (!gotname)
strcpy(daemon->namebuff, "query");
if (start->addr.sa.sa_family == AF_INET)
log_query(F_SERVER | F_IPV4 | F_FORWARD, daemon->namebuff,
(struct all_addr *)&start->addr.in.sin_addr, NULL);
#ifdef HAVE_IPV6
else
log_query(F_SERVER | F_IPV6 | F_FORWARD, daemon->namebuff,
(struct all_addr *)&start->addr.in6.sin6_addr, NULL);
#endif
start->queries++;
forwarded = 1;
forward->sentto = start;
if (!forward->forwardall)
break;
forward->forwardall++;
}
}
if (!(start = start->next))
start = daemon->servers;
if (start == firstsentto)
break;
}
if (forwarded)
return 1;
/* could not send on, prepare to return */
header->id = htons(forward->orig_id);
free_frec(forward); /* cancel */
}
/* could not send on, return empty answer or address if known for whole domain */
if (udpfd != -1)
{
plen = setup_reply(header, plen, addrp, flags, daemon->local_ttl);
send_from(udpfd, option_bool(OPT_NOWILD), (char *)header, plen, udpaddr, dst_addr, dst_iface);
}
return 0;
}
