diff options
Diffstat (limited to 'src/resolve/resolved-dns-stream.c')
| -rw-r--r-- | src/resolve/resolved-dns-stream.c | 380 |
1 files changed, 380 insertions, 0 deletions
diff --git a/src/resolve/resolved-dns-stream.c b/src/resolve/resolved-dns-stream.c new file mode 100644 index 0000000000..24a2288428 --- /dev/null +++ b/src/resolve/resolved-dns-stream.c @@ -0,0 +1,380 @@ +/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/ + +/*** + This file is part of systemd. + + Copyright 2014 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 <netinet/tcp.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); +} + +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; + 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 stream_complete(DnsStream *s, int error) { + assert(s); + + dns_stream_stop(s); + + if (s->complete) + s->complete(s, error); + else + dns_stream_free(s); + + return 0; +} + +static int on_stream_timeout(sd_event_source *es, usec_t usec, void *userdata) { + DnsStream *s = userdata; + + assert(s); + + return 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 ((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 = writev(fd, iov, 2); + if (ss < 0) { + if (errno != EINTR && errno != EAGAIN) + return stream_complete(s, errno); + } 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 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 = read(fd, (uint8_t*) &s->read_size + s->n_read, sizeof(s->read_size) - s->n_read); + if (ss < 0) { + if (errno != EINTR && errno != EAGAIN) + return stream_complete(s, errno); + } else if (ss == 0) + return 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 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)); + if (r < 0) + return 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 = read(fd, + (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 != EINTR && errno != EAGAIN) + return stream_complete(s, errno); + } else if (ss == 0) + return 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)) { + r = dns_stream_update_io(s); + if (r < 0) + return stream_complete(s, -r); + + /* If there's a packet handler + * installed, call that. Note that + * this is optional... */ + if (s->on_packet) + return s->on_packet(s); + } + } + } + + 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 stream_complete(s, 0); + + return 0; +} + +DnsStream *dns_stream_free(DnsStream *s) { + if (!s) + return NULL; + + dns_stream_stop(s); + + if (s->manager) { + LIST_REMOVE(streams, s->manager->dns_streams, s); + s->manager->n_dns_streams--; + } + + dns_packet_unref(s->write_packet); + dns_packet_unref(s->read_packet); + + free(s); + + return 0; +} + +DEFINE_TRIVIAL_CLEANUP_FUNC(DnsStream*, dns_stream_free); + +int dns_stream_new(Manager *m, DnsStream **ret, DnsProtocol protocol, int fd) { + static const int one = 1; + union { + struct cmsghdr header; /* For alignment */ + uint8_t buffer[CMSG_SPACE(MAX(sizeof(struct in_pktinfo), sizeof(struct in6_pktinfo))) + + EXTRA_CMSG_SPACE /* kernel appears to require extra space */]; + } control; + struct msghdr mh = {}; + struct cmsghdr *cmsg; + _cleanup_(dns_stream_freep) DnsStream *s = NULL; + socklen_t sl; + 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; + + s->fd = -1; + s->protocol = protocol; + + /* Query the remote side */ + s->peer_salen = sizeof(s->peer); + r = getpeername(fd, &s->peer.sa, &s->peer_salen); + if (r < 0) + return -errno; + if (s->peer.sa.sa_family == AF_INET6) + s->ifindex = s->peer.in6.sin6_scope_id; + + /* Query the local side */ + s->local_salen = sizeof(s->local); + r = getsockname(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; + + /* 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(fd, IPPROTO_IP, IP_PKTOPTIONS, &control, &sl); + if (r < 0) + return -errno; + } else { + assert(s->peer.sa.sa_family == AF_INET6); + + r = getsockopt(fd, IPPROTO_IPV6, IPV6_2292PKTOPTIONS, &control, &sl); + if (r < 0) + return -errno; + } + + mh.msg_control = &control; + mh.msg_controllen = sl; + for (cmsg = CMSG_FIRSTHDR(&mh); cmsg; cmsg = CMSG_NXTHDR(&mh, cmsg)) { + + 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 > 0 && manager_ifindex_is_loopback(m, s->ifindex) != 0) + 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(m, 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); + + r = setsockopt(fd, IPPROTO_TCP, TCP_NODELAY, &one, sizeof(one)); + if (r < 0) + return -errno; + + 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(fd, IPPROTO_IP, IP_UNICAST_IF, &ifindex, sizeof(ifindex)); + if (r < 0) + return -errno; + } else if (s->local.sa.sa_family == AF_INET6) { + r = setsockopt(fd, IPPROTO_IPV6, IPV6_UNICAST_IF, &ifindex, sizeof(ifindex)); + if (r < 0) + return -errno; + } + } + + r = sd_event_add_io(m->event, &s->io_event_source, fd, EPOLLIN, on_stream_io, s); + if (r < 0) + return r; + + r = sd_event_add_time(m->event, &s->timeout_event_source, CLOCK_MONOTONIC, now(CLOCK_MONOTONIC) + DNS_STREAM_TIMEOUT_USEC, 0, on_stream_timeout, s); + if (r < 0) + return r; + + LIST_PREPEND(streams, m->dns_streams, s); + s->manager = m; + s->fd = fd; + m->n_dns_streams++; + + *ret = s; + s = NULL; + + return 0; +} + +int dns_stream_write_packet(DnsStream *s, DnsPacket *p) { + assert(s); + + if (s->write_packet) + return -EBUSY; + + s->write_packet = dns_packet_ref(p); + s->write_size = htobe16(p->size); + s->n_written = 0; + + return dns_stream_update_io(s); +} |