resolved-dns-stream.c revision b914e211f3a40f507b3cdc572838ec7f3fd5e4cf
/*-*- 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 dns_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 dns_stream_identify(DnsStream *s) {
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;
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;
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(s->manager, 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(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)
return -errno;
} else if (s->local.sa.sa_family == AF_INET6) {
r = setsockopt(s->fd, IPPROTO_IPV6, IPV6_UNICAST_IF, &ifindex, sizeof(ifindex));
if (r < 0)
return -errno;
}
}
s->identified = true;
return 0;
}
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);
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 = writev(fd, iov, 2);
if (ss < 0) {
if (errno != EINTR && errno != EAGAIN)
return dns_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 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 = 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 dns_stream_complete(s, errno);
} 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));
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 = 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 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)) {
r = dns_stream_update_io(s);
if (r < 0)
return dns_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 dns_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;
_cleanup_(dns_stream_freep) 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;
s->fd = -1;
s->protocol = protocol;
r = setsockopt(fd, IPPROTO_TCP, TCP_NODELAY, &one, sizeof(one));
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);
}