summaryrefslogtreecommitdiff
path: root/src/resolve/resolved-dns-stub.c
diff options
context:
space:
mode:
Diffstat (limited to 'src/resolve/resolved-dns-stub.c')
-rw-r--r--src/resolve/resolved-dns-stub.c538
1 files changed, 0 insertions, 538 deletions
diff --git a/src/resolve/resolved-dns-stub.c b/src/resolve/resolved-dns-stub.c
deleted file mode 100644
index e76de6c06a..0000000000
--- a/src/resolve/resolved-dns-stub.c
+++ /dev/null
@@ -1,538 +0,0 @@
-/***
- This file is part of systemd.
-
- Copyright 2016 Lennart Poettering
-
- systemd is free software; you can redistribute it and/or modify it
- under the terms of the GNU Lesser General Public License as published by
- the Free Software Foundation; either version 2.1 of the License, or
- (at your option) any later version.
-
- systemd is distributed in the hope that it will be useful, but
- WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- Lesser General Public License for more details.
-
- You should have received a copy of the GNU Lesser General Public License
- along with systemd; If not, see <http://www.gnu.org/licenses/>.
-***/
-
-#include "fd-util.h"
-#include "resolved-dns-stub.h"
-#include "socket-util.h"
-
-/* The MTU of the loopback device is 64K on Linux, advertise that as maximum datagram size, but subtract the Ethernet,
- * IP and UDP header sizes */
-#define ADVERTISE_DATAGRAM_SIZE_MAX (65536U-14U-20U-8U)
-
-static int manager_dns_stub_udp_fd(Manager *m);
-static int manager_dns_stub_tcp_fd(Manager *m);
-
-static int dns_stub_make_reply_packet(
- uint16_t id,
- int rcode,
- DnsQuestion *q,
- DnsAnswer *answer,
- 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 */
- DnsPacket **ret) {
-
- _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
- DnsResourceRecord *rr;
- unsigned c = 0;
- int r;
-
- /* Note that we don't bother with any additional RRs, as this is stub is for local lookups only, and hence
- * roundtrips aren't expensive. */
-
- r = dns_packet_new(&p, DNS_PROTOCOL_DNS, 0);
- if (r < 0)
- return r;
-
- /* If the client didn't do EDNS, clamp the rcode to 4 bit */
- if (!add_opt && rcode > 0xF)
- rcode = DNS_RCODE_SERVFAIL;
-
- 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 */,
- ad /* ad */,
- 0 /* cd */,
- rcode));
-
- r = dns_packet_append_question(p, q);
- if (r < 0)
- return r;
- DNS_PACKET_HEADER(p)->qdcount = htobe16(dns_question_size(q));
-
- DNS_ANSWER_FOREACH(rr, answer) {
- r = dns_question_matches_rr(q, rr, NULL);
- if (r < 0)
- return r;
- if (r > 0)
- goto add;
-
- r = dns_question_matches_cname_or_dname(q, rr, NULL);
- if (r < 0)
- return r;
- if (r > 0)
- goto add;
-
- continue;
- add:
- r = dns_packet_append_rr(p, rr, NULL, NULL);
- if (r < 0)
- return r;
-
- c++;
- }
- DNS_PACKET_HEADER(p)->ancount = htobe16(c);
-
- if (add_opt) {
- r = dns_packet_append_opt(p, ADVERTISE_DATAGRAM_SIZE_MAX, edns0_do, rcode, NULL);
- if (r < 0)
- return r;
- }
-
- *ret = p;
- p = NULL;
-
- return 0;
-}
-
-static void dns_stub_detach_stream(DnsStream *s) {
- assert(s);
-
- s->complete = NULL;
- s->on_packet = NULL;
- s->query = NULL;
-}
-
-static int dns_stub_send(Manager *m, DnsStream *s, DnsPacket *p, DnsPacket *reply) {
- int r;
-
- assert(m);
- assert(p);
- assert(reply);
-
- if (s)
- r = dns_stream_write_packet(s, reply);
- 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");
-
- /* Note that it is essential here that we explicitly choose the source IP address for this packet. This
- * is because otherwise the kernel will choose it automatically based on the routing table and will
- * thus pick 127.0.0.1 rather than 127.0.0.53. */
-
- r = manager_send(m, fd, LOOPBACK_IFINDEX, p->family, &p->sender, p->sender_port, &p->destination, reply);
- }
- if (r < 0)
- return log_debug_errno(r, "Failed to send reply packet: %m");
-
- return 0;
-}
-
-static int dns_stub_send_failure(Manager *m, DnsStream *s, DnsPacket *p, int rcode) {
- _cleanup_(dns_packet_unrefp) DnsPacket *reply = NULL;
- int r;
-
- assert(m);
- assert(p);
-
- r = dns_stub_make_reply_packet(DNS_PACKET_ID(p), rcode, p->question, NULL, !!p->opt, DNS_PACKET_DO(p), false, &reply);
- if (r < 0)
- return log_debug_errno(r, "Failed to build failure packet: %m");
-
- return dns_stub_send(m, s, p, reply);
-}
-
-static void dns_stub_query_complete(DnsQuery *q) {
- int r;
-
- assert(q);
- assert(q->request_dns_packet);
-
- switch (q->state) {
-
- case DNS_TRANSACTION_SUCCESS: {
- _cleanup_(dns_packet_unrefp) DnsPacket *reply = NULL;
-
- r = dns_stub_make_reply_packet(
- DNS_PACKET_ID(q->request_dns_packet),
- q->answer_rcode,
- q->question_idna,
- q->answer,
- !!q->request_dns_packet->opt,
- DNS_PACKET_DO(q->request_dns_packet),
- DNS_PACKET_DO(q->request_dns_packet) && q->answer_authenticated,
- &reply);
- if (r < 0) {
- log_debug_errno(r, "Failed to build reply packet: %m");
- break;
- }
-
- (void) dns_stub_send(q->manager, q->request_dns_stream, q->request_dns_packet, reply);
- break;
- }
-
- case DNS_TRANSACTION_RCODE_FAILURE:
- (void) dns_stub_send_failure(q->manager, q->request_dns_stream, q->request_dns_packet, q->answer_rcode);
- break;
-
- case DNS_TRANSACTION_NOT_FOUND:
- (void) dns_stub_send_failure(q->manager, q->request_dns_stream, q->request_dns_packet, DNS_RCODE_NXDOMAIN);
- break;
-
- case DNS_TRANSACTION_TIMEOUT:
- case DNS_TRANSACTION_ATTEMPTS_MAX_REACHED:
- /* Propagate a timeout as a no packet, i.e. that the client also gets a timeout */
- break;
-
- case DNS_TRANSACTION_NO_SERVERS:
- case DNS_TRANSACTION_INVALID_REPLY:
- case DNS_TRANSACTION_ERRNO:
- case DNS_TRANSACTION_ABORTED:
- case DNS_TRANSACTION_DNSSEC_FAILED:
- 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);
- break;
-
- case DNS_TRANSACTION_NULL:
- case DNS_TRANSACTION_PENDING:
- case DNS_TRANSACTION_VALIDATING:
- default:
- assert_not_reached("Impossible state");
- }
-
- /* If there's a packet to write set, let's leave the stream around */
- if (q->request_dns_stream && DNS_STREAM_QUEUED(q->request_dns_stream)) {
-
- /* Detach the stream from our query (make it an orphan), but do not drop the reference to it. The
- * default completion action of the stream will drop the reference. */
-
- dns_stub_detach_stream(q->request_dns_stream);
- q->request_dns_stream = NULL;
- }
-
- dns_query_free(q);
-}
-
-static int dns_stub_stream_complete(DnsStream *s, int error) {
- assert(s);
-
- log_debug_errno(error, "DNS TCP connection terminated, destroying query: %m");
-
- assert(s->query);
- dns_query_free(s->query);
-
- return 0;
-}
-
-static void dns_stub_process_query(Manager *m, DnsStream *s, DnsPacket *p) {
- DnsQuery *q = NULL;
- int r;
-
- assert(m);
- assert(p);
- assert(p->protocol == DNS_PROTOCOL_DNS);
-
- /* Takes ownership of the *s stream object */
-
- 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);
- 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);
- 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);
- 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);
- 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);
- 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);
- 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);
- goto fail;
- }
-
- r = dns_query_new(m, &q, p->question, p->question, 0, SD_RESOLVED_PROTOCOLS_ALL|SD_RESOLVED_NO_SEARCH|SD_RESOLVED_NO_CNAME);
- if (r < 0) {
- log_error_errno(r, "Failed to generate query object: %m");
- dns_stub_send_failure(m, s, p, DNS_RCODE_SERVFAIL);
- goto fail;
- }
-
- /* Request that the TTL is corrected by the cached time for this lookup, so that we return vaguely useful TTLs */
- q->clamp_ttl = true;
-
- q->request_dns_packet = dns_packet_ref(p);
- q->request_dns_stream = dns_stream_ref(s); /* make sure the stream stays around until we can send a reply through it */
- q->complete = dns_stub_query_complete;
-
- if (s) {
- s->on_packet = NULL;
- s->complete = dns_stub_stream_complete;
- s->query = q;
- }
-
- 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);
- goto fail;
- }
-
- log_info("Processing query...");
- return;
-
-fail:
- if (s && DNS_STREAM_QUEUED(s))
- dns_stub_detach_stream(s);
-
- dns_query_free(q);
-}
-
-static int on_dns_stub_packet(sd_event_source *s, int fd, uint32_t revents, void *userdata) {
- _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
- Manager *m = userdata;
- int r;
-
- r = manager_recv(m, fd, DNS_PROTOCOL_DNS, &p);
- if (r <= 0)
- return r;
-
- if (dns_packet_validate_query(p) > 0) {
- log_debug("Got DNS stub UDP query packet for id %u", DNS_PACKET_ID(p));
-
- dns_stub_process_query(m, NULL, p);
- } else
- log_debug("Invalid DNS stub UDP packet, ignoring.");
-
- return 0;
-}
-
-static int manager_dns_stub_udp_fd(Manager *m) {
- static const int one = 1;
- union sockaddr_union sa = {
- .in.sin_family = AF_INET,
- .in.sin_port = htobe16(53),
- .in.sin_addr.s_addr = htobe32(INADDR_DNS_STUB),
- };
- _cleanup_close_ int fd = -1;
- int r;
-
- if (m->dns_stub_udp_fd >= 0)
- return m->dns_stub_udp_fd;
-
- fd = socket(AF_INET, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
- if (fd < 0)
- return -errno;
-
- if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof one) < 0)
- return -errno;
-
- if (setsockopt(fd, IPPROTO_IP, IP_PKTINFO, &one, sizeof one) < 0)
- return -errno;
-
- if (setsockopt(fd, IPPROTO_IP, IP_RECVTTL, &one, sizeof one) < 0)
- return -errno;
-
- /* Make sure no traffic from outside the local host can leak to onto this socket */
- if (setsockopt(fd, SOL_SOCKET, SO_BINDTODEVICE, "lo", 3) < 0)
- return -errno;
-
- if (bind(fd, &sa.sa, sizeof(sa.in)) < 0)
- return -errno;
-
- r = sd_event_add_io(m->event, &m->dns_stub_udp_event_source, fd, EPOLLIN, on_dns_stub_packet, m);
- if (r < 0)
- return r;
-
- (void) sd_event_source_set_description(m->dns_stub_udp_event_source, "dns-stub-udp");
- m->dns_stub_udp_fd = fd;
- fd = -1;
-
- return m->dns_stub_udp_fd;
-}
-
-static int on_dns_stub_stream_packet(DnsStream *s) {
- assert(s);
- assert(s->read_packet);
-
- if (dns_packet_validate_query(s->read_packet) > 0) {
- log_debug("Got DNS stub TCP query packet for id %u", DNS_PACKET_ID(s->read_packet));
-
- dns_stub_process_query(s->manager, s, s->read_packet);
- } else
- log_debug("Invalid DNS stub TCP packet, ignoring.");
-
- /* Drop the reference to the stream. Either a query was created and added its own reference to the stream now,
- * or that didn't happen in which case we want to free the stream */
- dns_stream_unref(s);
-
- return 0;
-}
-
-static int on_dns_stub_stream(sd_event_source *s, int fd, uint32_t revents, void *userdata) {
- DnsStream *stream;
- Manager *m = userdata;
- int cfd, r;
-
- cfd = accept4(fd, NULL, NULL, SOCK_NONBLOCK|SOCK_CLOEXEC);
- if (cfd < 0) {
- if (errno == EAGAIN || errno == EINTR)
- return 0;
-
- return -errno;
- }
-
- r = dns_stream_new(m, &stream, DNS_PROTOCOL_DNS, cfd);
- if (r < 0) {
- safe_close(cfd);
- return r;
- }
-
- stream->on_packet = on_dns_stub_stream_packet;
-
- /* We let the reference to the stream dangling here, it will either be dropped by the default "complete" action
- * of the stream, or by our packet callback, or when the manager is shut down. */
-
- return 0;
-}
-
-static int manager_dns_stub_tcp_fd(Manager *m) {
- static const int one = 1;
- union sockaddr_union sa = {
- .in.sin_family = AF_INET,
- .in.sin_addr.s_addr = htobe32(INADDR_DNS_STUB),
- .in.sin_port = htobe16(53),
- };
- _cleanup_close_ int fd = -1;
- int r;
-
- if (m->dns_stub_tcp_fd >= 0)
- return m->dns_stub_tcp_fd;
-
- fd = socket(AF_INET, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
- if (fd < 0)
- return -errno;
-
- if (setsockopt(fd, IPPROTO_IP, IP_TTL, &one, sizeof one) < 0)
- return -errno;
-
- if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof one) < 0)
- return -errno;
-
- if (setsockopt(fd, IPPROTO_IP, IP_PKTINFO, &one, sizeof one) < 0)
- return -errno;
-
- if (setsockopt(fd, IPPROTO_IP, IP_RECVTTL, &one, sizeof one) < 0)
- return -errno;
-
- /* Make sure no traffic from outside the local host can leak to onto this socket */
- if (setsockopt(fd, SOL_SOCKET, SO_BINDTODEVICE, "lo", 3) < 0)
- return -errno;
-
- if (bind(fd, &sa.sa, sizeof(sa.in)) < 0)
- return -errno;
-
- if (listen(fd, SOMAXCONN) < 0)
- return -errno;
-
- r = sd_event_add_io(m->event, &m->dns_stub_tcp_event_source, fd, EPOLLIN, on_dns_stub_stream, m);
- if (r < 0)
- return r;
-
- (void) sd_event_source_set_description(m->dns_stub_tcp_event_source, "dns-stub-tcp");
- m->dns_stub_tcp_fd = fd;
- fd = -1;
-
- return m->dns_stub_tcp_fd;
-}
-
-int manager_dns_stub_start(Manager *m) {
- const char *t = "UDP";
- int r = 0;
-
- assert(m);
-
- if (IN_SET(m->dns_stub_listener_mode, DNS_STUB_LISTENER_YES, DNS_STUB_LISTENER_UDP))
- r = manager_dns_stub_udp_fd(m);
-
- if (r >= 0 &&
- IN_SET(m->dns_stub_listener_mode, DNS_STUB_LISTENER_YES, DNS_STUB_LISTENER_TCP)) {
- t = "TCP";
- r = manager_dns_stub_tcp_fd(m);
- }
-
- if (IN_SET(r, -EADDRINUSE, -EPERM)) {
- if (r == -EADDRINUSE)
- log_warning_errno(r,
- "Another process is already listening on %s socket 127.0.0.53:53.\n"
- "Turning off local DNS stub support.", t);
- else
- log_warning_errno(r,
- "Failed to listen on %s socket 127.0.0.53:53: %m.\n"
- "Turning off local DNS stub support.", t);
- manager_dns_stub_stop(m);
- } else if (r < 0)
- return log_error_errno(r, "Failed to listen on %s socket 127.0.0.53:53: %m", t);
-
- return 0;
-}
-
-void manager_dns_stub_stop(Manager *m) {
- assert(m);
-
- m->dns_stub_udp_event_source = sd_event_source_unref(m->dns_stub_udp_event_source);
- m->dns_stub_tcp_event_source = sd_event_source_unref(m->dns_stub_tcp_event_source);
-
- m->dns_stub_udp_fd = safe_close(m->dns_stub_udp_fd);
- m->dns_stub_tcp_fd = safe_close(m->dns_stub_tcp_fd);
-}
generated by cgit v1.2.3 (git 2.25.1) at 2024-06-01 14:43:04 +0000