/* 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
#define WRITE_TLS_DATA 1
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);
}
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;
return sd_event_source_set_io_events(s->io_event_source, f);
}
static int dns_stream_complete(DnsStream *s, int error) {
assert(s);
#if ENABLE_DNS_OVER_TLS
if (s->tls_session && IN_SET(error, ETIMEDOUT, 0)) {
int r;
r = gnutls_bye(s->tls_session, GNUTLS_SHUT_RDWR);
if (r == GNUTLS_E_AGAIN && !s->tls_bye) {
dns_stream_ref(s); /* keep reference for closing TLS session */
s->tls_bye = true;
} else
dns_stream_stop(s);
} else
#endif
dns_stream_stop(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;
}
static ssize_t dns_stream_writev(DnsStream *s, const struct iovec *iov, size_t iovcnt, int flags) {
ssize_t r;
assert(s);
assert(iov);
#if ENABLE_DNS_OVER_TLS
if (s->tls_session && !(flags & WRITE_TLS_DATA)) {
ssize_t ss;
size_t i;
r = 0;
for (i = 0; i < iovcnt; i++) {
ss = gnutls_record_send(s->tls_session, iov[i].iov_base, iov[i].iov_len);
if (ss < 0) {
switch(ss) {
case GNUTLS_E_INTERRUPTED:
return -EINTR;
case GNUTLS_E_AGAIN:
return -EAGAIN;
default:
log_debug("Failed to invoke gnutls_record_send: %s", gnutls_strerror(ss));
return -EIO;
}
}
r += 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
};
r = sendmsg(s->fd, &hdr, MSG_FASTOPEN);
if (r < 0) {
if (errno == EOPNOTSUPP) {
s->tfo_salen = 0;
r = connect(s->fd, &s->tfo_address.sa, s->tfo_salen);
if (r < 0)
return -errno;
r = -EAGAIN;
} else if (errno == EINPROGRESS)
r = -EAGAIN;
} else
s->tfo_salen = 0; /* connection is made */
} else {
r = writev(s->fd, iov, iovcnt);
if (r < 0)
r = -errno;
}
return r;
}
static ssize_t dns_stream_read(DnsStream *s, void *buf, size_t count) {
ssize_t ss;
#if ENABLE_DNS_OVER_TLS
if (s->tls_session) {
ss = gnutls_record_recv(s->tls_session, buf, count);
if (ss < 0) {
switch(ss) {
case GNUTLS_E_INTERRUPTED:
return -EINTR;
case GNUTLS_E_AGAIN:
return -EAGAIN;
default:
log_debug("Failed to invoke gnutls_record_send: %s", gnutls_strerror(ss));
return -EIO;
}
} else if (s->on_connection) {
int r;
r = s->on_connection(s);
s->on_connection = NULL; /* only call once */
if (r < 0)
return r;
}
} else
#endif
{
ss = read(s->fd, buf, count);
if (ss < 0)
ss = -errno;
}
return ss;
}
#if ENABLE_DNS_OVER_TLS
static ssize_t dns_stream_tls_writev(gnutls_transport_ptr_t p, const giovec_t * iov, int iovcnt) {
int r;
assert(p);
r = dns_stream_writev((DnsStream*) p, (struct iovec*) iov, iovcnt, WRITE_TLS_DATA);
if (r < 0) {
errno = -r;
return -1;
}
return r;
}
#endif
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) {
DnsStream *s = userdata;
int r;
assert(s);
#if ENABLE_DNS_OVER_TLS
if (s->tls_bye) {
assert(s->tls_session);
r = gnutls_bye(s->tls_session, GNUTLS_SHUT_RDWR);
if (r != GNUTLS_E_AGAIN) {
s->tls_bye = false;
dns_stream_unref(s);
}
return 0;
}
if (s->tls_handshake < 0) {
assert(s->tls_session);
s->tls_handshake = gnutls_handshake(s->tls_session);
if (s->tls_handshake >= 0) {
if (s->on_connection && !(gnutls_session_get_flags(s->tls_session) & GNUTLS_SFLAGS_FALSE_START)) {
r = s->on_connection(s);
s->on_connection = NULL; /* only call once */
if (r < 0)
return r;
}
} else {
if (gnutls_error_is_fatal(s->tls_handshake))
return dns_stream_complete(s, ECONNREFUSED);
else
return 0;
}
}
#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].iov_base = &s->write_size;
iov[0].iov_len = sizeof(s->write_size);
iov[1].iov_base = DNS_PACKET_DATA(s->write_packet);
iov[1].iov_len = 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(errno, EINTR, EAGAIN))
return dns_stream_complete(s, errno);
} 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;
}
DnsStream *dns_stream_unref(DnsStream *s) {
DnsPacket *p;
Iterator i;
if (!s)
return NULL;
assert(s->n_ref > 0);
s->n_ref--;
if (s->n_ref > 0)
return NULL;
dns_stream_stop(s);
if (s->server && s->server->stream == s)
s->server->stream = NULL;
if (s->manager) {
LIST_REMOVE(streams, s->manager->dns_streams, s);
s->manager->n_dns_streams--;
}
#if ENABLE_DNS_OVER_TLS
if (s->tls_session)
gnutls_deinit(s->tls_session);
#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);
}
DnsStream *dns_stream_ref(DnsStream *s) {
if (!s)
return NULL;
assert(s->n_ref > 0);
s->n_ref++;
return s;
}
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(fd >= 0);
if (m->n_dns_streams > DNS_STREAMS_MAX)
return -EBUSY;
s = new0(DnsStream, 1);
if (!s)
return -ENOMEM;
r = ordered_set_ensure_allocated(&s->write_queue, &dns_packet_hash_ops);
if (r < 0)
return r;
s->n_ref = 1;
s->fd = -1;
s->protocol = protocol;
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);
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);
}
m->n_dns_streams++;
*ret = TAKE_PTR(s);
return 0;
}
#if ENABLE_DNS_OVER_TLS
int dns_stream_connect_tls(DnsStream *s, gnutls_session_t tls_session) {
gnutls_transport_set_ptr2(tls_session, (gnutls_transport_ptr_t) (long) s->fd, s);
gnutls_transport_set_vec_push_function(tls_session, &dns_stream_tls_writev);
s->encrypted = true;
s->tls_session = tls_session;
s->tls_handshake = gnutls_handshake(tls_session);
if (s->tls_handshake < 0 && gnutls_error_is_fatal(s->tls_handshake))
return -ECONNREFUSED;
return 0;
}
#endif
int dns_stream_write_packet(DnsStream *s, DnsPacket *p) {
int r;
assert(s);
r = ordered_set_put(s->write_queue, p);
if (r < 0)
return r;
dns_packet_ref(p);
return dns_stream_update_io(s);
}