summaryrefslogtreecommitdiffstats
path: root/src/resolve/resolved-dns-stream.c
diff options
context:
space:
mode:
Diffstat (limited to '')
-rw-r--r--src/resolve/resolved-dns-stream.c595
1 files changed, 595 insertions, 0 deletions
diff --git a/src/resolve/resolved-dns-stream.c b/src/resolve/resolved-dns-stream.c
new file mode 100644
index 0000000..95fbb56
--- /dev/null
+++ b/src/resolve/resolved-dns-stream.c
@@ -0,0 +1,595 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <netinet/tcp.h>
+#include <unistd.h>
+
+#include "alloc-util.h"
+#include "fd-util.h"
+#include "io-util.h"
+#include "macro.h"
+#include "missing_network.h"
+#include "resolved-dns-stream.h"
+#include "resolved-manager.h"
+
+#define DNS_STREAMS_MAX 128
+
+#define DNS_QUERIES_PER_STREAM 32
+
+static void dns_stream_stop(DnsStream *s) {
+ assert(s);
+
+ s->io_event_source = sd_event_source_disable_unref(s->io_event_source);
+ s->timeout_event_source = sd_event_source_disable_unref(s->timeout_event_source);
+ s->fd = safe_close(s->fd);
+
+ /* Disconnect us from the server object if we are now not usable anymore */
+ dns_stream_detach(s);
+}
+
+static int dns_stream_update_io(DnsStream *s) {
+ uint32_t f = 0;
+
+ assert(s);
+
+ if (s->write_packet && s->n_written < sizeof(s->write_size) + s->write_packet->size)
+ f |= EPOLLOUT;
+ else if (!ordered_set_isempty(s->write_queue)) {
+ dns_packet_unref(s->write_packet);
+ s->write_packet = ordered_set_steal_first(s->write_queue);
+ s->write_size = htobe16(s->write_packet->size);
+ s->n_written = 0;
+ f |= EPOLLOUT;
+ }
+
+ /* Let's read a packet if we haven't queued any yet. Except if we already hit a limit of parallel
+ * queries for this connection. */
+ if ((!s->read_packet || s->n_read < sizeof(s->read_size) + s->read_packet->size) &&
+ set_size(s->queries) < DNS_QUERIES_PER_STREAM)
+ f |= EPOLLIN;
+
+ s->requested_events = f;
+
+#if ENABLE_DNS_OVER_TLS
+ /* For handshake and clean closing purposes, TLS can override requested events */
+ if (s->dnstls_events != 0)
+ f = s->dnstls_events;
+#endif
+
+ return sd_event_source_set_io_events(s->io_event_source, f);
+}
+
+static int dns_stream_complete(DnsStream *s, int error) {
+ _cleanup_(dns_stream_unrefp) _unused_ DnsStream *ref = dns_stream_ref(s); /* Protect stream while we process it */
+
+ assert(s);
+ assert(error >= 0);
+
+ /* Error is > 0 when the connection failed for some reason in the network stack. It's == 0 if we sent
+ * and received exactly one packet each (in the LLMNR client case). */
+
+#if ENABLE_DNS_OVER_TLS
+ if (s->encrypted) {
+ int r;
+
+ r = dnstls_stream_shutdown(s, error);
+ if (r != -EAGAIN)
+ dns_stream_stop(s);
+ } else
+#endif
+ dns_stream_stop(s);
+
+ dns_stream_detach(s);
+
+ if (s->complete)
+ s->complete(s, error);
+ else /* the default action if no completion function is set is to close the stream */
+ dns_stream_unref(s);
+
+ return 0;
+}
+
+static int dns_stream_identify(DnsStream *s) {
+ CMSG_BUFFER_TYPE(CMSG_SPACE(MAXSIZE(struct in_pktinfo, struct in6_pktinfo))
+ + CMSG_SPACE(int) + /* for the TTL */
+ + EXTRA_CMSG_SPACE /* kernel appears to require extra space */) control;
+ struct msghdr mh = {};
+ struct cmsghdr *cmsg;
+ socklen_t sl;
+ int r;
+
+ assert(s);
+
+ if (s->identified)
+ return 0;
+
+ /* Query the local side */
+ s->local_salen = sizeof(s->local);
+ r = getsockname(s->fd, &s->local.sa, &s->local_salen);
+ if (r < 0)
+ return -errno;
+ if (s->local.sa.sa_family == AF_INET6 && s->ifindex <= 0)
+ s->ifindex = s->local.in6.sin6_scope_id;
+
+ /* Query the remote side */
+ s->peer_salen = sizeof(s->peer);
+ r = getpeername(s->fd, &s->peer.sa, &s->peer_salen);
+ if (r < 0)
+ return -errno;
+ if (s->peer.sa.sa_family == AF_INET6 && s->ifindex <= 0)
+ s->ifindex = s->peer.in6.sin6_scope_id;
+
+ /* Check consistency */
+ assert(s->peer.sa.sa_family == s->local.sa.sa_family);
+ assert(IN_SET(s->peer.sa.sa_family, AF_INET, AF_INET6));
+
+ /* Query connection meta information */
+ sl = sizeof(control);
+ if (s->peer.sa.sa_family == AF_INET) {
+ r = getsockopt(s->fd, IPPROTO_IP, IP_PKTOPTIONS, &control, &sl);
+ if (r < 0)
+ return -errno;
+ } else if (s->peer.sa.sa_family == AF_INET6) {
+
+ r = getsockopt(s->fd, IPPROTO_IPV6, IPV6_2292PKTOPTIONS, &control, &sl);
+ if (r < 0)
+ return -errno;
+ } else
+ return -EAFNOSUPPORT;
+
+ mh.msg_control = &control;
+ mh.msg_controllen = sl;
+
+ CMSG_FOREACH(cmsg, &mh) {
+
+ if (cmsg->cmsg_level == IPPROTO_IPV6) {
+ assert(s->peer.sa.sa_family == AF_INET6);
+
+ switch (cmsg->cmsg_type) {
+
+ case IPV6_PKTINFO: {
+ struct in6_pktinfo *i = (struct in6_pktinfo*) CMSG_DATA(cmsg);
+
+ if (s->ifindex <= 0)
+ s->ifindex = i->ipi6_ifindex;
+ break;
+ }
+
+ case IPV6_HOPLIMIT:
+ s->ttl = *(int *) CMSG_DATA(cmsg);
+ break;
+ }
+
+ } else if (cmsg->cmsg_level == IPPROTO_IP) {
+ assert(s->peer.sa.sa_family == AF_INET);
+
+ switch (cmsg->cmsg_type) {
+
+ case IP_PKTINFO: {
+ struct in_pktinfo *i = (struct in_pktinfo*) CMSG_DATA(cmsg);
+
+ if (s->ifindex <= 0)
+ s->ifindex = i->ipi_ifindex;
+ break;
+ }
+
+ case IP_TTL:
+ s->ttl = *(int *) CMSG_DATA(cmsg);
+ break;
+ }
+ }
+ }
+
+ /* The Linux kernel sets the interface index to the loopback
+ * device if the connection came from the local host since it
+ * avoids the routing table in such a case. Let's unset the
+ * interface index in such a case. */
+ if (s->ifindex == LOOPBACK_IFINDEX)
+ s->ifindex = 0;
+
+ /* If we don't know the interface index still, we look for the
+ * first local interface with a matching address. Yuck! */
+ if (s->ifindex <= 0)
+ s->ifindex = manager_find_ifindex(s->manager, s->local.sa.sa_family, sockaddr_in_addr(&s->local.sa));
+
+ if (s->protocol == DNS_PROTOCOL_LLMNR && s->ifindex > 0) {
+ /* Make sure all packets for this connection are sent on the same interface */
+ r = socket_set_unicast_if(s->fd, s->local.sa.sa_family, s->ifindex);
+ if (r < 0)
+ log_debug_errno(errno, "Failed to invoke IP_UNICAST_IF/IPV6_UNICAST_IF: %m");
+ }
+
+ s->identified = true;
+
+ return 0;
+}
+
+ssize_t dns_stream_writev(DnsStream *s, const struct iovec *iov, size_t iovcnt, int flags) {
+ ssize_t m;
+
+ assert(s);
+ assert(iov);
+
+#if ENABLE_DNS_OVER_TLS
+ if (s->encrypted && !(flags & DNS_STREAM_WRITE_TLS_DATA))
+ return dnstls_stream_writev(s, iov, iovcnt);
+#endif
+
+ if (s->tfo_salen > 0) {
+ struct msghdr hdr = {
+ .msg_iov = (struct iovec*) iov,
+ .msg_iovlen = iovcnt,
+ .msg_name = &s->tfo_address.sa,
+ .msg_namelen = s->tfo_salen
+ };
+
+ m = sendmsg(s->fd, &hdr, MSG_FASTOPEN);
+ if (m < 0) {
+ if (errno == EOPNOTSUPP) {
+ s->tfo_salen = 0;
+ if (connect(s->fd, &s->tfo_address.sa, s->tfo_salen) < 0)
+ return -errno;
+
+ return -EAGAIN;
+ }
+ if (errno == EINPROGRESS)
+ return -EAGAIN;
+
+ return -errno;
+ } else
+ s->tfo_salen = 0; /* connection is made */
+ } else {
+ m = writev(s->fd, iov, iovcnt);
+ if (m < 0)
+ return -errno;
+ }
+
+ return m;
+}
+
+static ssize_t dns_stream_read(DnsStream *s, void *buf, size_t count) {
+ ssize_t ss;
+
+#if ENABLE_DNS_OVER_TLS
+ if (s->encrypted)
+ ss = dnstls_stream_read(s, buf, count);
+ else
+#endif
+ {
+ ss = read(s->fd, buf, count);
+ if (ss < 0)
+ return -errno;
+ }
+
+ return ss;
+}
+
+static int on_stream_timeout(sd_event_source *es, usec_t usec, void *userdata) {
+ DnsStream *s = ASSERT_PTR(userdata);
+
+ return dns_stream_complete(s, ETIMEDOUT);
+}
+
+static DnsPacket *dns_stream_take_read_packet(DnsStream *s) {
+ assert(s);
+
+ /* Note, dns_stream_update() should be called after this is called. When this is called, the
+ * stream may be already full and the EPOLLIN flag is dropped from the stream IO event source.
+ * Even this makes a room to read in the stream, this does not call dns_stream_update(), hence
+ * EPOLLIN flag is not set automatically. So, to read further packets from the stream,
+ * dns_stream_update() must be called explicitly. Currently, this is only called from
+ * on_stream_io(), and there dns_stream_update() is called. */
+
+ if (!s->read_packet)
+ return NULL;
+
+ if (s->n_read < sizeof(s->read_size))
+ return NULL;
+
+ if (s->n_read < sizeof(s->read_size) + be16toh(s->read_size))
+ return NULL;
+
+ s->n_read = 0;
+ return TAKE_PTR(s->read_packet);
+}
+
+static int on_stream_io(sd_event_source *es, int fd, uint32_t revents, void *userdata) {
+ _cleanup_(dns_stream_unrefp) DnsStream *s = dns_stream_ref(userdata); /* Protect stream while we process it */
+ bool progressed = false;
+ int r;
+
+ assert(s);
+
+#if ENABLE_DNS_OVER_TLS
+ if (s->encrypted) {
+ r = dnstls_stream_on_io(s, revents);
+ if (r == DNSTLS_STREAM_CLOSED)
+ return 0;
+ if (r == -EAGAIN)
+ return dns_stream_update_io(s);
+ if (r < 0)
+ return dns_stream_complete(s, -r);
+
+ r = dns_stream_update_io(s);
+ if (r < 0)
+ return r;
+ }
+#endif
+
+ /* only identify after connecting */
+ if (s->tfo_salen == 0) {
+ r = dns_stream_identify(s);
+ if (r < 0)
+ return dns_stream_complete(s, -r);
+ }
+
+ if ((revents & EPOLLOUT) &&
+ s->write_packet &&
+ s->n_written < sizeof(s->write_size) + s->write_packet->size) {
+
+ struct iovec iov[] = {
+ IOVEC_MAKE(&s->write_size, sizeof(s->write_size)),
+ IOVEC_MAKE(DNS_PACKET_DATA(s->write_packet), s->write_packet->size),
+ };
+
+ IOVEC_INCREMENT(iov, ELEMENTSOF(iov), s->n_written);
+
+ ssize_t ss = dns_stream_writev(s, iov, ELEMENTSOF(iov), 0);
+ if (ss < 0) {
+ if (!ERRNO_IS_TRANSIENT(ss))
+ return dns_stream_complete(s, -ss);
+ } else {
+ progressed = true;
+ s->n_written += ss;
+ }
+
+ /* Are we done? If so, disable the event source for EPOLLOUT */
+ if (s->n_written >= sizeof(s->write_size) + s->write_packet->size) {
+ r = dns_stream_update_io(s);
+ if (r < 0)
+ return dns_stream_complete(s, -r);
+ }
+ }
+
+ while ((revents & (EPOLLIN|EPOLLHUP|EPOLLRDHUP)) &&
+ (!s->read_packet ||
+ s->n_read < sizeof(s->read_size) + s->read_packet->size)) {
+
+ if (s->n_read < sizeof(s->read_size)) {
+ ssize_t ss;
+
+ ss = dns_stream_read(s, (uint8_t*) &s->read_size + s->n_read, sizeof(s->read_size) - s->n_read);
+ if (ss < 0) {
+ if (!ERRNO_IS_TRANSIENT(ss))
+ return dns_stream_complete(s, -ss);
+ break;
+ } else if (ss == 0)
+ return dns_stream_complete(s, ECONNRESET);
+ else {
+ progressed = true;
+ s->n_read += ss;
+ }
+ }
+
+ if (s->n_read >= sizeof(s->read_size)) {
+
+ if (be16toh(s->read_size) < DNS_PACKET_HEADER_SIZE)
+ return dns_stream_complete(s, EBADMSG);
+
+ if (s->n_read < sizeof(s->read_size) + be16toh(s->read_size)) {
+ ssize_t ss;
+
+ if (!s->read_packet) {
+ r = dns_packet_new(&s->read_packet, s->protocol, be16toh(s->read_size), DNS_PACKET_SIZE_MAX);
+ if (r < 0)
+ return dns_stream_complete(s, -r);
+
+ s->read_packet->size = be16toh(s->read_size);
+ s->read_packet->ipproto = IPPROTO_TCP;
+ s->read_packet->family = s->peer.sa.sa_family;
+ s->read_packet->ttl = s->ttl;
+ s->read_packet->ifindex = s->ifindex;
+ s->read_packet->timestamp = now(CLOCK_BOOTTIME);
+
+ if (s->read_packet->family == AF_INET) {
+ s->read_packet->sender.in = s->peer.in.sin_addr;
+ s->read_packet->sender_port = be16toh(s->peer.in.sin_port);
+ s->read_packet->destination.in = s->local.in.sin_addr;
+ s->read_packet->destination_port = be16toh(s->local.in.sin_port);
+ } else {
+ assert(s->read_packet->family == AF_INET6);
+ s->read_packet->sender.in6 = s->peer.in6.sin6_addr;
+ s->read_packet->sender_port = be16toh(s->peer.in6.sin6_port);
+ s->read_packet->destination.in6 = s->local.in6.sin6_addr;
+ s->read_packet->destination_port = be16toh(s->local.in6.sin6_port);
+
+ if (s->read_packet->ifindex == 0)
+ s->read_packet->ifindex = s->peer.in6.sin6_scope_id;
+ if (s->read_packet->ifindex == 0)
+ s->read_packet->ifindex = s->local.in6.sin6_scope_id;
+ }
+ }
+
+ ss = dns_stream_read(s,
+ (uint8_t*) DNS_PACKET_DATA(s->read_packet) + s->n_read - sizeof(s->read_size),
+ sizeof(s->read_size) + be16toh(s->read_size) - s->n_read);
+ if (ss < 0) {
+ if (!ERRNO_IS_TRANSIENT(ss))
+ return dns_stream_complete(s, -ss);
+ break;
+ } else if (ss == 0)
+ return dns_stream_complete(s, ECONNRESET);
+ else
+ s->n_read += ss;
+ }
+
+ /* Are we done? If so, call the packet handler and re-enable EPOLLIN for the
+ * event source if necessary. */
+ _cleanup_(dns_packet_unrefp) DnsPacket *p = dns_stream_take_read_packet(s);
+ if (p) {
+ assert(s->on_packet);
+ r = s->on_packet(s, p);
+ if (r < 0)
+ return r;
+
+ r = dns_stream_update_io(s);
+ if (r < 0)
+ return dns_stream_complete(s, -r);
+
+ s->packet_received = true;
+
+ /* If we just disabled the read event, stop reading */
+ if (!FLAGS_SET(s->requested_events, EPOLLIN))
+ break;
+ }
+ }
+ }
+
+ /* Complete the stream if finished reading and writing one packet, and there's nothing
+ * else left to write. */
+ if (s->type == DNS_STREAM_LLMNR_SEND && s->packet_received &&
+ !FLAGS_SET(s->requested_events, EPOLLOUT))
+ return dns_stream_complete(s, 0);
+
+ /* If we did something, let's restart the timeout event source */
+ if (progressed && s->timeout_event_source) {
+ r = sd_event_source_set_time_relative(s->timeout_event_source, DNS_STREAM_ESTABLISHED_TIMEOUT_USEC);
+ if (r < 0)
+ log_warning_errno(errno, "Couldn't restart TCP connection timeout, ignoring: %m");
+ }
+
+ return 0;
+}
+
+static DnsStream *dns_stream_free(DnsStream *s) {
+ DnsPacket *p;
+
+ assert(s);
+
+ dns_stream_stop(s);
+
+ if (s->manager) {
+ LIST_REMOVE(streams, s->manager->dns_streams, s);
+ s->manager->n_dns_streams[s->type]--;
+ }
+
+#if ENABLE_DNS_OVER_TLS
+ if (s->encrypted)
+ dnstls_stream_free(s);
+#endif
+
+ ORDERED_SET_FOREACH(p, s->write_queue)
+ dns_packet_unref(ordered_set_remove(s->write_queue, p));
+
+ dns_packet_unref(s->write_packet);
+ dns_packet_unref(s->read_packet);
+ dns_server_unref(s->server);
+
+ ordered_set_free(s->write_queue);
+
+ return mfree(s);
+}
+
+DEFINE_TRIVIAL_REF_UNREF_FUNC(DnsStream, dns_stream, dns_stream_free);
+
+int dns_stream_new(
+ Manager *m,
+ DnsStream **ret,
+ DnsStreamType type,
+ DnsProtocol protocol,
+ int fd,
+ const union sockaddr_union *tfo_address,
+ int (on_packet)(DnsStream*, DnsPacket*),
+ int (complete)(DnsStream*, int), /* optional */
+ usec_t connect_timeout_usec) {
+
+ _cleanup_(dns_stream_unrefp) DnsStream *s = NULL;
+ int r;
+
+ assert(m);
+ assert(ret);
+ assert(type >= 0);
+ assert(type < _DNS_STREAM_TYPE_MAX);
+ assert(protocol >= 0);
+ assert(protocol < _DNS_PROTOCOL_MAX);
+ assert(fd >= 0);
+ assert(on_packet);
+
+ if (m->n_dns_streams[type] > DNS_STREAMS_MAX)
+ return -EBUSY;
+
+ s = new(DnsStream, 1);
+ if (!s)
+ return -ENOMEM;
+
+ *s = (DnsStream) {
+ .n_ref = 1,
+ .fd = -1,
+ .protocol = protocol,
+ .type = type,
+ };
+
+ r = ordered_set_ensure_allocated(&s->write_queue, &dns_packet_hash_ops);
+ if (r < 0)
+ return r;
+
+ r = sd_event_add_io(m->event, &s->io_event_source, fd, EPOLLIN, on_stream_io, s);
+ if (r < 0)
+ return r;
+
+ (void) sd_event_source_set_description(s->io_event_source, "dns-stream-io");
+
+ r = sd_event_add_time_relative(
+ m->event,
+ &s->timeout_event_source,
+ CLOCK_BOOTTIME,
+ connect_timeout_usec, 0,
+ on_stream_timeout, s);
+ if (r < 0)
+ return r;
+
+ (void) sd_event_source_set_description(s->timeout_event_source, "dns-stream-timeout");
+
+ LIST_PREPEND(streams, m->dns_streams, s);
+ m->n_dns_streams[type]++;
+ s->manager = m;
+
+ s->fd = fd;
+ s->on_packet = on_packet;
+ s->complete = complete;
+
+ if (tfo_address) {
+ s->tfo_address = *tfo_address;
+ s->tfo_salen = tfo_address->sa.sa_family == AF_INET6 ? sizeof(tfo_address->in6) : sizeof(tfo_address->in);
+ }
+
+ *ret = TAKE_PTR(s);
+
+ return 0;
+}
+
+int dns_stream_write_packet(DnsStream *s, DnsPacket *p) {
+ int r;
+
+ assert(s);
+ assert(p);
+
+ r = ordered_set_put(s->write_queue, p);
+ if (r < 0)
+ return r;
+
+ dns_packet_ref(p);
+
+ return dns_stream_update_io(s);
+}
+
+void dns_stream_detach(DnsStream *s) {
+ assert(s);
+
+ if (!s->server)
+ return;
+
+ if (s->server->stream != s)
+ return;
+
+ dns_server_unref_stream(s->server);
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-28 11:07:17 +0000