406 lines
15 KiB
C
406 lines
15 KiB
C
/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
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/***
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This file is part of systemd.
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Copyright 2014 Lennart Poettering
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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***/
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#include <netinet/tcp.h>
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#include "alloc-util.h"
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#include "fd-util.h"
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#include "io-util.h"
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#include "missing.h"
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#include "resolved-dns-stream.h"
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#define DNS_STREAM_TIMEOUT_USEC (10 * USEC_PER_SEC)
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#define DNS_STREAMS_MAX 128
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static void dns_stream_stop(DnsStream *s) {
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assert(s);
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s->io_event_source = sd_event_source_unref(s->io_event_source);
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s->timeout_event_source = sd_event_source_unref(s->timeout_event_source);
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s->fd = safe_close(s->fd);
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}
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static int dns_stream_update_io(DnsStream *s) {
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int f = 0;
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assert(s);
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if (s->write_packet && s->n_written < sizeof(s->write_size) + s->write_packet->size)
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f |= EPOLLOUT;
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if (!s->read_packet || s->n_read < sizeof(s->read_size) + s->read_packet->size)
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f |= EPOLLIN;
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return sd_event_source_set_io_events(s->io_event_source, f);
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}
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static int dns_stream_complete(DnsStream *s, int error) {
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assert(s);
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dns_stream_stop(s);
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if (s->complete)
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s->complete(s, error);
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else
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dns_stream_free(s);
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return 0;
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}
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static int dns_stream_identify(DnsStream *s) {
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union {
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struct cmsghdr header; /* For alignment */
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uint8_t buffer[CMSG_SPACE(MAXSIZE(struct in_pktinfo, struct in6_pktinfo))
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+ EXTRA_CMSG_SPACE /* kernel appears to require extra space */];
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} control;
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struct msghdr mh = {};
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struct cmsghdr *cmsg;
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socklen_t sl;
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int r;
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assert(s);
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if (s->identified)
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return 0;
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/* Query the local side */
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s->local_salen = sizeof(s->local);
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r = getsockname(s->fd, &s->local.sa, &s->local_salen);
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if (r < 0)
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return -errno;
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if (s->local.sa.sa_family == AF_INET6 && s->ifindex <= 0)
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s->ifindex = s->local.in6.sin6_scope_id;
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/* Query the remote side */
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s->peer_salen = sizeof(s->peer);
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r = getpeername(s->fd, &s->peer.sa, &s->peer_salen);
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if (r < 0)
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return -errno;
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if (s->peer.sa.sa_family == AF_INET6 && s->ifindex <= 0)
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s->ifindex = s->peer.in6.sin6_scope_id;
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/* Check consistency */
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assert(s->peer.sa.sa_family == s->local.sa.sa_family);
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assert(IN_SET(s->peer.sa.sa_family, AF_INET, AF_INET6));
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/* Query connection meta information */
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sl = sizeof(control);
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if (s->peer.sa.sa_family == AF_INET) {
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r = getsockopt(s->fd, IPPROTO_IP, IP_PKTOPTIONS, &control, &sl);
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if (r < 0)
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return -errno;
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} else if (s->peer.sa.sa_family == AF_INET6) {
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r = getsockopt(s->fd, IPPROTO_IPV6, IPV6_2292PKTOPTIONS, &control, &sl);
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if (r < 0)
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return -errno;
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} else
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return -EAFNOSUPPORT;
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mh.msg_control = &control;
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mh.msg_controllen = sl;
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CMSG_FOREACH(cmsg, &mh) {
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if (cmsg->cmsg_level == IPPROTO_IPV6) {
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assert(s->peer.sa.sa_family == AF_INET6);
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switch (cmsg->cmsg_type) {
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case IPV6_PKTINFO: {
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struct in6_pktinfo *i = (struct in6_pktinfo*) CMSG_DATA(cmsg);
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if (s->ifindex <= 0)
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s->ifindex = i->ipi6_ifindex;
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break;
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}
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case IPV6_HOPLIMIT:
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s->ttl = *(int *) CMSG_DATA(cmsg);
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break;
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}
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} else if (cmsg->cmsg_level == IPPROTO_IP) {
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assert(s->peer.sa.sa_family == AF_INET);
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switch (cmsg->cmsg_type) {
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case IP_PKTINFO: {
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struct in_pktinfo *i = (struct in_pktinfo*) CMSG_DATA(cmsg);
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if (s->ifindex <= 0)
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s->ifindex = i->ipi_ifindex;
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break;
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}
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case IP_TTL:
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s->ttl = *(int *) CMSG_DATA(cmsg);
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break;
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}
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}
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}
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/* The Linux kernel sets the interface index to the loopback
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* device if the connection came from the local host since it
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* avoids the routing table in such a case. Let's unset the
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* interface index in such a case. */
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if (s->ifindex == LOOPBACK_IFINDEX)
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s->ifindex = 0;
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/* If we don't know the interface index still, we look for the
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* first local interface with a matching address. Yuck! */
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if (s->ifindex <= 0)
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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);
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if (s->protocol == DNS_PROTOCOL_LLMNR && s->ifindex > 0) {
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uint32_t ifindex = htobe32(s->ifindex);
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/* Make sure all packets for this connection are sent on the same interface */
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if (s->local.sa.sa_family == AF_INET) {
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r = setsockopt(s->fd, IPPROTO_IP, IP_UNICAST_IF, &ifindex, sizeof(ifindex));
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if (r < 0)
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log_debug_errno(errno, "Failed to invoke IP_UNICAST_IF: %m");
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} else if (s->local.sa.sa_family == AF_INET6) {
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r = setsockopt(s->fd, IPPROTO_IPV6, IPV6_UNICAST_IF, &ifindex, sizeof(ifindex));
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if (r < 0)
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log_debug_errno(errno, "Failed to invoke IPV6_UNICAST_IF: %m");
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}
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}
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s->identified = true;
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return 0;
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}
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static int on_stream_timeout(sd_event_source *es, usec_t usec, void *userdata) {
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DnsStream *s = userdata;
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assert(s);
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return dns_stream_complete(s, ETIMEDOUT);
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}
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static int on_stream_io(sd_event_source *es, int fd, uint32_t revents, void *userdata) {
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DnsStream *s = userdata;
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int r;
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assert(s);
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r = dns_stream_identify(s);
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if (r < 0)
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return dns_stream_complete(s, -r);
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if ((revents & EPOLLOUT) &&
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s->write_packet &&
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s->n_written < sizeof(s->write_size) + s->write_packet->size) {
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struct iovec iov[2];
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ssize_t ss;
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iov[0].iov_base = &s->write_size;
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iov[0].iov_len = sizeof(s->write_size);
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iov[1].iov_base = DNS_PACKET_DATA(s->write_packet);
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iov[1].iov_len = s->write_packet->size;
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IOVEC_INCREMENT(iov, 2, s->n_written);
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ss = writev(fd, iov, 2);
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if (ss < 0) {
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if (errno != EINTR && errno != EAGAIN)
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return dns_stream_complete(s, errno);
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} else
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s->n_written += ss;
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/* Are we done? If so, disable the event source for EPOLLOUT */
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if (s->n_written >= sizeof(s->write_size) + s->write_packet->size) {
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r = dns_stream_update_io(s);
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if (r < 0)
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return dns_stream_complete(s, -r);
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}
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}
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if ((revents & (EPOLLIN|EPOLLHUP|EPOLLRDHUP)) &&
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(!s->read_packet ||
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s->n_read < sizeof(s->read_size) + s->read_packet->size)) {
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if (s->n_read < sizeof(s->read_size)) {
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ssize_t ss;
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ss = read(fd, (uint8_t*) &s->read_size + s->n_read, sizeof(s->read_size) - s->n_read);
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if (ss < 0) {
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if (errno != EINTR && errno != EAGAIN)
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return dns_stream_complete(s, errno);
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} else if (ss == 0)
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return dns_stream_complete(s, ECONNRESET);
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else
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s->n_read += ss;
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}
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if (s->n_read >= sizeof(s->read_size)) {
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if (be16toh(s->read_size) < DNS_PACKET_HEADER_SIZE)
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return dns_stream_complete(s, EBADMSG);
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if (s->n_read < sizeof(s->read_size) + be16toh(s->read_size)) {
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ssize_t ss;
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if (!s->read_packet) {
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r = dns_packet_new(&s->read_packet, s->protocol, be16toh(s->read_size));
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if (r < 0)
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return dns_stream_complete(s, -r);
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s->read_packet->size = be16toh(s->read_size);
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s->read_packet->ipproto = IPPROTO_TCP;
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s->read_packet->family = s->peer.sa.sa_family;
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s->read_packet->ttl = s->ttl;
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s->read_packet->ifindex = s->ifindex;
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if (s->read_packet->family == AF_INET) {
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s->read_packet->sender.in = s->peer.in.sin_addr;
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s->read_packet->sender_port = be16toh(s->peer.in.sin_port);
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s->read_packet->destination.in = s->local.in.sin_addr;
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s->read_packet->destination_port = be16toh(s->local.in.sin_port);
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} else {
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assert(s->read_packet->family == AF_INET6);
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s->read_packet->sender.in6 = s->peer.in6.sin6_addr;
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s->read_packet->sender_port = be16toh(s->peer.in6.sin6_port);
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s->read_packet->destination.in6 = s->local.in6.sin6_addr;
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s->read_packet->destination_port = be16toh(s->local.in6.sin6_port);
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if (s->read_packet->ifindex == 0)
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s->read_packet->ifindex = s->peer.in6.sin6_scope_id;
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if (s->read_packet->ifindex == 0)
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s->read_packet->ifindex = s->local.in6.sin6_scope_id;
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}
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}
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ss = read(fd,
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(uint8_t*) DNS_PACKET_DATA(s->read_packet) + s->n_read - sizeof(s->read_size),
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sizeof(s->read_size) + be16toh(s->read_size) - s->n_read);
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if (ss < 0) {
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if (errno != EINTR && errno != EAGAIN)
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return dns_stream_complete(s, errno);
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} else if (ss == 0)
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return dns_stream_complete(s, ECONNRESET);
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else
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s->n_read += ss;
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}
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/* Are we done? If so, disable the event source for EPOLLIN */
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if (s->n_read >= sizeof(s->read_size) + be16toh(s->read_size)) {
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r = dns_stream_update_io(s);
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if (r < 0)
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return dns_stream_complete(s, -r);
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/* If there's a packet handler
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* installed, call that. Note that
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* this is optional... */
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if (s->on_packet)
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return s->on_packet(s);
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}
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}
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}
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if ((s->write_packet && s->n_written >= sizeof(s->write_size) + s->write_packet->size) &&
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(s->read_packet && s->n_read >= sizeof(s->read_size) + s->read_packet->size))
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return dns_stream_complete(s, 0);
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return 0;
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}
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DnsStream *dns_stream_free(DnsStream *s) {
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if (!s)
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return NULL;
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dns_stream_stop(s);
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if (s->manager) {
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LIST_REMOVE(streams, s->manager->dns_streams, s);
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s->manager->n_dns_streams--;
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}
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dns_packet_unref(s->write_packet);
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dns_packet_unref(s->read_packet);
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free(s);
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return 0;
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}
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DEFINE_TRIVIAL_CLEANUP_FUNC(DnsStream*, dns_stream_free);
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int dns_stream_new(Manager *m, DnsStream **ret, DnsProtocol protocol, int fd) {
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_cleanup_(dns_stream_freep) DnsStream *s = NULL;
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int r;
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assert(m);
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assert(fd >= 0);
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if (m->n_dns_streams > DNS_STREAMS_MAX)
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return -EBUSY;
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s = new0(DnsStream, 1);
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if (!s)
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return -ENOMEM;
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s->fd = -1;
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s->protocol = protocol;
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r = sd_event_add_io(m->event, &s->io_event_source, fd, EPOLLIN, on_stream_io, s);
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if (r < 0)
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return r;
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(void) sd_event_source_set_description(s->io_event_source, "dns-stream-io");
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r = sd_event_add_time(
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m->event,
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&s->timeout_event_source,
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clock_boottime_or_monotonic(),
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now(clock_boottime_or_monotonic()) + DNS_STREAM_TIMEOUT_USEC, 0,
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on_stream_timeout, s);
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if (r < 0)
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return r;
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(void) sd_event_source_set_description(s->timeout_event_source, "dns-stream-timeout");
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LIST_PREPEND(streams, m->dns_streams, s);
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s->manager = m;
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s->fd = fd;
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m->n_dns_streams++;
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*ret = s;
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s = NULL;
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return 0;
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}
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int dns_stream_write_packet(DnsStream *s, DnsPacket *p) {
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assert(s);
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if (s->write_packet)
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return -EBUSY;
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s->write_packet = dns_packet_ref(p);
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s->write_size = htobe16(p->size);
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s->n_written = 0;
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return dns_stream_update_io(s);
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}
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