diff options
Diffstat (limited to 'src/resolve/resolved-dns-stream.c')
| -rw-r--r-- | src/resolve/resolved-dns-stream.c | 567 |
1 files changed, 567 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..aee339a --- /dev/null +++ b/src/resolve/resolved-dns-stream.c @@ -0,0 +1,567 @@ +/* SPDX-License-Identifier: LGPL-2.1+ */ + +#include <netinet/tcp.h> + +#include "alloc-util.h" +#include "fd-util.h" +#include "io-util.h" +#include "missing.h" +#include "resolved-dns-stream.h" + +#define DNS_STREAM_TIMEOUT_USEC (10 * USEC_PER_SEC) +#define DNS_STREAMS_MAX 128 + +static void dns_stream_stop(DnsStream *s) { + assert(s); + + s->io_event_source = sd_event_source_unref(s->io_event_source); + s->timeout_event_source = sd_event_source_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) { + int 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; + } + if (!s->read_packet || s->n_read < sizeof(s->read_size) + s->read_packet->size) + f |= EPOLLIN; + +#if ENABLE_DNS_OVER_TLS + /* For handshake and clean closing purposes, TLS can override requested events */ + if (s->dnstls_events) + 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); + +#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) { + union { + struct cmsghdr header; /* For alignment */ + uint8_t buffer[CMSG_SPACE(MAXSIZE(struct in_pktinfo, struct in6_pktinfo)) + + 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, s->local.sa.sa_family == AF_INET ? (union in_addr_union*) &s->local.in.sin_addr : (union in_addr_union*) &s->local.in6.sin6_addr); + + if (s->protocol == DNS_PROTOCOL_LLMNR && s->ifindex > 0) { + uint32_t ifindex = htobe32(s->ifindex); + + /* Make sure all packets for this connection are sent on the same interface */ + if (s->local.sa.sa_family == AF_INET) { + r = setsockopt(s->fd, IPPROTO_IP, IP_UNICAST_IF, &ifindex, sizeof(ifindex)); + if (r < 0) + log_debug_errno(errno, "Failed to invoke IP_UNICAST_IF: %m"); + } else if (s->local.sa.sa_family == AF_INET6) { + r = setsockopt(s->fd, IPPROTO_IPV6, IPV6_UNICAST_IF, &ifindex, sizeof(ifindex)); + if (r < 0) + log_debug_errno(errno, "Failed to invoke 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)) { + ssize_t ss; + size_t i; + + m = 0; + for (i = 0; i < iovcnt; i++) { + ss = dnstls_stream_write(s, iov[i].iov_base, iov[i].iov_len); + if (ss < 0) + return ss; + + m += ss; + if (ss != (ssize_t) iov[i].iov_len) + continue; + } + } else +#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 = userdata; + + assert(s); + + return dns_stream_complete(s, ETIMEDOUT); +} + +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 */ + 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[2]; + ssize_t ss; + + iov[0] = IOVEC_MAKE(&s->write_size, sizeof(s->write_size)); + iov[1] = IOVEC_MAKE(DNS_PACKET_DATA(s->write_packet), s->write_packet->size); + + IOVEC_INCREMENT(iov, 2, s->n_written); + + ss = dns_stream_writev(s, iov, 2, 0); + if (ss < 0) { + if (!IN_SET(-ss, EINTR, EAGAIN)) + return dns_stream_complete(s, -ss); + } else + 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); + } + } + + if ((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 (!IN_SET(-ss, EINTR, EAGAIN)) + return dns_stream_complete(s, -ss); + } else if (ss == 0) + return dns_stream_complete(s, ECONNRESET); + else + 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; + + 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 (!IN_SET(-ss, EINTR, EAGAIN)) + return dns_stream_complete(s, -ss); + } else if (ss == 0) + return dns_stream_complete(s, ECONNRESET); + else + s->n_read += ss; + } + + /* Are we done? If so, disable the event source for EPOLLIN */ + if (s->n_read >= sizeof(s->read_size) + be16toh(s->read_size)) { + /* If there's a packet handler + * installed, call that. Note that + * this is optional... */ + if (s->on_packet) { + r = s->on_packet(s); + if (r < 0) + return r; + } + + r = dns_stream_update_io(s); + if (r < 0) + return dns_stream_complete(s, -r); + } + } + } + + if ((s->write_packet && s->n_written >= sizeof(s->write_size) + s->write_packet->size) && + (s->read_packet && s->n_read >= sizeof(s->read_size) + s->read_packet->size)) + return dns_stream_complete(s, 0); + + return 0; +} + +static DnsStream *dns_stream_free(DnsStream *s) { + DnsPacket *p; + Iterator i; + + assert(s); + + dns_stream_stop(s); + + if (s->manager) { + LIST_REMOVE(streams, s->manager->dns_streams, s); + s->manager->n_dns_streams--; + } + +#if ENABLE_DNS_OVER_TLS + if (s->encrypted) + dnstls_stream_free(s); +#endif + + ORDERED_SET_FOREACH(p, s->write_queue, i) + 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, + DnsProtocol protocol, + int fd, + const union sockaddr_union *tfo_address) { + + _cleanup_(dns_stream_unrefp) DnsStream *s = NULL; + int r; + + assert(m); + assert(ret); + assert(fd >= 0); + + if (m->n_dns_streams > DNS_STREAMS_MAX) + return -EBUSY; + + s = new(DnsStream, 1); + if (!s) + return -ENOMEM; + + *s = (DnsStream) { + .n_ref = 1, + .fd = -1, + .protocol = protocol, + }; + + 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( + m->event, + &s->timeout_event_source, + clock_boottime_or_monotonic(), + now(clock_boottime_or_monotonic()) + DNS_STREAM_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++; + s->manager = m; + + s->fd = fd; + + 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); +} + +DnsPacket *dns_stream_take_read_packet(DnsStream *s) { + assert(s); + + 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); +} + +void dns_stream_detach(DnsStream *s) { + assert(s); + + if (!s->server) + return; + + if (s->server->stream != s) + return; + + dns_server_unref_stream(s->server); +} |