+/* SPDX-License-Identifier: LGPL-2.1+ */
/***
This file is part of systemd.
static int dns_stub_make_reply_packet(
DnsPacket **p,
+ size_t max_size,
DnsQuestion *q,
- DnsAnswer *answer) {
+ DnsAnswer *answer,
+ bool *ret_truncated) {
+ bool truncated = false;
DnsResourceRecord *rr;
unsigned c = 0;
int r;
* roundtrips aren't expensive. */
if (!*p) {
- r = dns_packet_new(p, DNS_PROTOCOL_DNS, 0);
+ r = dns_packet_new(p, DNS_PROTOCOL_DNS, 0, max_size);
if (r < 0)
return r;
continue;
add:
r = dns_packet_append_rr(*p, rr, 0, NULL, NULL);
+ if (r == -EMSGSIZE) {
+ truncated = true;
+ break;
+ }
if (r < 0)
return r;
c++;
}
+ if (ret_truncated)
+ *ret_truncated = truncated;
+ else if (truncated)
+ return -EMSGSIZE;
+
DNS_PACKET_HEADER(*p)->ancount = htobe16(be16toh(DNS_PACKET_HEADER(*p)->ancount) + c);
return 0;
DnsPacket *p,
uint16_t id,
int rcode,
+ bool tc, /* set the Truncated bit? */
bool add_opt, /* add an OPT RR to this packet? */
bool edns0_do, /* set the EDNS0 DNSSEC OK bit? */
bool ad) { /* set the DNSSEC authenticated data bit? */
assert(p);
- /* If the client didn't do EDNS, clamp the rcode to 4 bit */
- if (!add_opt && rcode > 0xF)
- rcode = DNS_RCODE_SERVFAIL;
+ if (!add_opt) {
+ /* If the client can't to EDNS0, don't do DO either */
+ edns0_do = false;
+
+ /* If the client didn't do EDNS, clamp the rcode to 4 bit */
+ if (rcode > 0xF)
+ rcode = DNS_RCODE_SERVFAIL;
+ }
+
+ /* Don't set the AD bit unless DO is on, too */
+ if (!edns0_do)
+ ad = false;
DNS_PACKET_HEADER(p)->id = id;
DNS_PACKET_HEADER(p)->flags = htobe16(DNS_PACKET_MAKE_FLAGS(
- 1 /* qr */,
- 0 /* opcode */,
- 0 /* aa */,
- 0 /* tc */,
- 1 /* rd */,
- 1 /* ra */,
+ 1 /* qr */,
+ 0 /* opcode */,
+ 0 /* aa */,
+ tc /* tc */,
+ 1 /* rd */,
+ 1 /* ra */,
ad /* ad */,
- 0 /* cd */,
+ 0 /* cd */,
rcode));
if (add_opt) {
else {
int fd;
- /* Truncate the message to the right size */
- if (reply->size > DNS_PACKET_PAYLOAD_SIZE_MAX(p)) {
- dns_packet_truncate(reply, DNS_PACKET_UNICAST_SIZE_MAX);
- DNS_PACKET_HEADER(reply)->flags = htobe16(be16toh(DNS_PACKET_HEADER(reply)->flags) | DNS_PACKET_FLAG_TC);
- }
-
fd = manager_dns_stub_udp_fd(m);
if (fd < 0)
return log_debug_errno(fd, "Failed to get reply socket: %m");
return 0;
}
-static int dns_stub_send_failure(Manager *m, DnsStream *s, DnsPacket *p, int rcode) {
+static int dns_stub_send_failure(Manager *m, DnsStream *s, DnsPacket *p, int rcode, bool authenticated) {
_cleanup_(dns_packet_unrefp) DnsPacket *reply = NULL;
int r;
assert(m);
assert(p);
- r = dns_stub_make_reply_packet(&reply, p->question, NULL);
+ r = dns_stub_make_reply_packet(&reply, DNS_PACKET_PAYLOAD_SIZE_MAX(p), p->question, NULL, NULL);
if (r < 0)
return log_debug_errno(r, "Failed to make failure packet: %m");
- r = dns_stub_finish_reply_packet(reply, DNS_PACKET_ID(p), rcode, !!p->opt, DNS_PACKET_DO(p), false);
+ r = dns_stub_finish_reply_packet(reply, DNS_PACKET_ID(p), rcode, false, !!p->opt, DNS_PACKET_DO(p), authenticated);
if (r < 0)
return log_debug_errno(r, "Failed to build failure packet: %m");
switch (q->state) {
- case DNS_TRANSACTION_SUCCESS:
+ case DNS_TRANSACTION_SUCCESS: {
+ bool truncated;
- r = dns_stub_make_reply_packet(&q->reply_dns_packet, q->question_idna, q->answer);
+ r = dns_stub_make_reply_packet(&q->reply_dns_packet, DNS_PACKET_PAYLOAD_SIZE_MAX(q->request_dns_packet), q->question_idna, q->answer, &truncated);
if (r < 0) {
log_debug_errno(r, "Failed to build reply packet: %m");
break;
r = dns_query_process_cname(q);
if (r == -ELOOP) {
- (void) dns_stub_send_failure(q->manager, q->request_dns_stream, q->request_dns_packet, DNS_RCODE_SERVFAIL);
+ (void) dns_stub_send_failure(q->manager, q->request_dns_stream, q->request_dns_packet, DNS_RCODE_SERVFAIL, false);
break;
}
if (r < 0) {
q->reply_dns_packet,
DNS_PACKET_ID(q->request_dns_packet),
q->answer_rcode,
+ truncated,
!!q->request_dns_packet->opt,
DNS_PACKET_DO(q->request_dns_packet),
- DNS_PACKET_DO(q->request_dns_packet) && dns_query_fully_authenticated(q));
+ dns_query_fully_authenticated(q));
if (r < 0) {
log_debug_errno(r, "Failed to finish reply packet: %m");
break;
(void) dns_stub_send(q->manager, q->request_dns_stream, q->request_dns_packet, q->reply_dns_packet);
break;
+ }
case DNS_TRANSACTION_RCODE_FAILURE:
- (void) dns_stub_send_failure(q->manager, q->request_dns_stream, q->request_dns_packet, q->answer_rcode);
+ (void) dns_stub_send_failure(q->manager, q->request_dns_stream, q->request_dns_packet, q->answer_rcode, dns_query_fully_authenticated(q));
break;
case DNS_TRANSACTION_NOT_FOUND:
- (void) dns_stub_send_failure(q->manager, q->request_dns_stream, q->request_dns_packet, DNS_RCODE_NXDOMAIN);
+ (void) dns_stub_send_failure(q->manager, q->request_dns_stream, q->request_dns_packet, DNS_RCODE_NXDOMAIN, dns_query_fully_authenticated(q));
break;
case DNS_TRANSACTION_TIMEOUT:
case DNS_TRANSACTION_NO_TRUST_ANCHOR:
case DNS_TRANSACTION_RR_TYPE_UNSUPPORTED:
case DNS_TRANSACTION_NETWORK_DOWN:
- (void) dns_stub_send_failure(q->manager, q->request_dns_stream, q->request_dns_packet, DNS_RCODE_SERVFAIL);
+ (void) dns_stub_send_failure(q->manager, q->request_dns_stream, q->request_dns_packet, DNS_RCODE_SERVFAIL, false);
break;
case DNS_TRANSACTION_NULL:
if (in_addr_is_localhost(p->family, &p->sender) <= 0 ||
in_addr_is_localhost(p->family, &p->destination) <= 0) {
log_error("Got packet on unexpected IP range, refusing.");
- dns_stub_send_failure(m, s, p, DNS_RCODE_SERVFAIL);
+ dns_stub_send_failure(m, s, p, DNS_RCODE_SERVFAIL, false);
goto fail;
}
r = dns_packet_extract(p);
if (r < 0) {
log_debug_errno(r, "Failed to extract resources from incoming packet, ignoring packet: %m");
- dns_stub_send_failure(m, s, p, DNS_RCODE_FORMERR);
+ dns_stub_send_failure(m, s, p, DNS_RCODE_FORMERR, false);
goto fail;
}
if (!DNS_PACKET_VERSION_SUPPORTED(p)) {
log_debug("Got EDNS OPT field with unsupported version number.");
- dns_stub_send_failure(m, s, p, DNS_RCODE_BADVERS);
+ dns_stub_send_failure(m, s, p, DNS_RCODE_BADVERS, false);
goto fail;
}
if (dns_type_is_obsolete(p->question->keys[0]->type)) {
log_debug("Got message with obsolete key type, refusing.");
- dns_stub_send_failure(m, s, p, DNS_RCODE_NOTIMP);
+ dns_stub_send_failure(m, s, p, DNS_RCODE_NOTIMP, false);
goto fail;
}
if (dns_type_is_zone_transer(p->question->keys[0]->type)) {
log_debug("Got request for zone transfer, refusing.");
- dns_stub_send_failure(m, s, p, DNS_RCODE_NOTIMP);
+ dns_stub_send_failure(m, s, p, DNS_RCODE_NOTIMP, false);
goto fail;
}
if (!DNS_PACKET_RD(p)) {
/* If the "rd" bit is off (i.e. recursion was not requested), then refuse operation */
log_debug("Got request with recursion disabled, refusing.");
- dns_stub_send_failure(m, s, p, DNS_RCODE_REFUSED);
+ dns_stub_send_failure(m, s, p, DNS_RCODE_REFUSED, false);
goto fail;
}
if (DNS_PACKET_DO(p) && DNS_PACKET_CD(p)) {
log_debug("Got request with DNSSEC CD bit set, refusing.");
- dns_stub_send_failure(m, s, p, DNS_RCODE_NOTIMP);
+ dns_stub_send_failure(m, s, p, DNS_RCODE_NOTIMP, false);
goto fail;
}
r = dns_query_new(m, &q, p->question, p->question, 0, SD_RESOLVED_PROTOCOLS_ALL|SD_RESOLVED_NO_SEARCH);
if (r < 0) {
log_error_errno(r, "Failed to generate query object: %m");
- dns_stub_send_failure(m, s, p, DNS_RCODE_SERVFAIL);
+ dns_stub_send_failure(m, s, p, DNS_RCODE_SERVFAIL, false);
goto fail;
}
r = dns_query_go(q);
if (r < 0) {
log_error_errno(r, "Failed to start query: %m");
- dns_stub_send_failure(m, s, p, DNS_RCODE_SERVFAIL);
+ dns_stub_send_failure(m, s, p, DNS_RCODE_SERVFAIL, false);
goto fail;
}
cfd = accept4(fd, NULL, NULL, SOCK_NONBLOCK|SOCK_CLOEXEC);
if (cfd < 0) {
- if (errno == EAGAIN || errno == EINTR)
+ if (IN_SET(errno, EAGAIN, EINTR))
return 0;
return -errno;
assert(m);
+ if (m->dns_stub_listener_mode == DNS_STUB_LISTENER_NO)
+ log_debug("Not creating stub listener.");
+ else
+ log_debug("Creating stub listener using %s.",
+ m->dns_stub_listener_mode == DNS_STUB_LISTENER_UDP ? "UDP" :
+ m->dns_stub_listener_mode == DNS_STUB_LISTENER_TCP ? "TCP" :
+ "UDP/TCP");
+
if (IN_SET(m->dns_stub_listener_mode, DNS_STUB_LISTENER_YES, DNS_STUB_LISTENER_UDP))
r = manager_dns_stub_udp_fd(m);