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Systemd/src/resolve/resolved-llmnr.c
Zbigniew Jędrzejewski-Szmek 11a1589223 tree-wide: drop license boilerplate 
Files which are installed as-is (any .service and other unit files, .conf
files, .policy files, etc), are left as is. My assumption is that SPDX
identifiers are not yet that well known, so it's better to retain the
extended header to avoid any doubt.

I also kept any copyright lines. We can probably remove them, but it'd nice to
obtain explicit acks from all involved authors before doing that.
2018-04-06 18:58:55 +02:00

542 lines
20 KiB
C
Raw Blame History

/* SPDX-License-Identifier: LGPL-2.1+ */
/***
This file is part of systemd.
Copyright 2014 Tom Gundersen <teg@jklm.no>
***/
#include <netinet/in.h>
#include <resolv.h>
#include "fd-util.h"
#include "resolved-llmnr.h"
#include "resolved-manager.h"
void manager_llmnr_stop(Manager *m) {
assert(m);
m->llmnr_ipv4_udp_event_source = sd_event_source_unref(m->llmnr_ipv4_udp_event_source);
m->llmnr_ipv4_udp_fd = safe_close(m->llmnr_ipv4_udp_fd);
m->llmnr_ipv6_udp_event_source = sd_event_source_unref(m->llmnr_ipv6_udp_event_source);
m->llmnr_ipv6_udp_fd = safe_close(m->llmnr_ipv6_udp_fd);
m->llmnr_ipv4_tcp_event_source = sd_event_source_unref(m->llmnr_ipv4_tcp_event_source);
m->llmnr_ipv4_tcp_fd = safe_close(m->llmnr_ipv4_tcp_fd);
m->llmnr_ipv6_tcp_event_source = sd_event_source_unref(m->llmnr_ipv6_tcp_event_source);
m->llmnr_ipv6_tcp_fd = safe_close(m->llmnr_ipv6_tcp_fd);
}
int manager_llmnr_start(Manager *m) {
int r;
assert(m);
if (m->llmnr_support == RESOLVE_SUPPORT_NO)
return 0;
r = manager_llmnr_ipv4_udp_fd(m);
if (r == -EADDRINUSE)
goto eaddrinuse;
if (r < 0)
return r;
r = manager_llmnr_ipv4_tcp_fd(m);
if (r == -EADDRINUSE)
goto eaddrinuse;
if (r < 0)
return r;
if (socket_ipv6_is_supported()) {
r = manager_llmnr_ipv6_udp_fd(m);
if (r == -EADDRINUSE)
goto eaddrinuse;
if (r < 0)
return r;
r = manager_llmnr_ipv6_tcp_fd(m);
if (r == -EADDRINUSE)
goto eaddrinuse;
if (r < 0)
return r;
}
return 0;
eaddrinuse:
log_warning("Another LLMNR responder prohibits binding the socket to the same port. Turning off LLMNR support.");
m->llmnr_support = RESOLVE_SUPPORT_NO;
manager_llmnr_stop(m);
return 0;
}
static int on_llmnr_packet(sd_event_source *s, int fd, uint32_t revents, void *userdata) {
_cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
DnsTransaction *t = NULL;
Manager *m = userdata;
DnsScope *scope;
int r;
assert(s);
assert(fd >= 0);
assert(m);
r = manager_recv(m, fd, DNS_PROTOCOL_LLMNR, &p);
if (r <= 0)
return r;
if (manager_our_packet(m, p))
return 0;
scope = manager_find_scope(m, p);
if (!scope) {
log_debug("Got LLMNR UDP packet on unknown scope. Ignoring.");
return 0;
}
if (dns_packet_validate_reply(p) > 0) {
log_debug("Got LLMNR UDP reply packet for id %u", DNS_PACKET_ID(p));
dns_scope_check_conflicts(scope, p);
t = hashmap_get(m->dns_transactions, UINT_TO_PTR(DNS_PACKET_ID(p)));
if (t)
dns_transaction_process_reply(t, p);
} else if (dns_packet_validate_query(p) > 0) {
log_debug("Got LLMNR UDP query packet for id %u", DNS_PACKET_ID(p));
dns_scope_process_query(scope, NULL, p);
} else
log_debug("Invalid LLMNR UDP packet, ignoring.");
return 0;
}
int manager_llmnr_ipv4_udp_fd(Manager *m) {
union sockaddr_union sa = {
.in.sin_family = AF_INET,
.in.sin_port = htobe16(LLMNR_PORT),
};
static const int one = 1, pmtu = IP_PMTUDISC_DONT, ttl = 255;
int r;
assert(m);
if (m->llmnr_ipv4_udp_fd >= 0)
return m->llmnr_ipv4_udp_fd;
m->llmnr_ipv4_udp_fd = socket(AF_INET, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
if (m->llmnr_ipv4_udp_fd < 0)
return log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to create socket: %m");
/* RFC 4795, section 2.5 recommends setting the TTL of UDP packets to 255. */
r = setsockopt(m->llmnr_ipv4_udp_fd, IPPROTO_IP, IP_TTL, &ttl, sizeof(ttl));
if (r < 0) {
r = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to set IP_TTL: %m");
goto fail;
}
r = setsockopt(m->llmnr_ipv4_udp_fd, IPPROTO_IP, IP_MULTICAST_TTL, &ttl, sizeof(ttl));
if (r < 0) {
r = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to set IP_MULTICAST_TTL: %m");
goto fail;
}
r = setsockopt(m->llmnr_ipv4_udp_fd, IPPROTO_IP, IP_MULTICAST_LOOP, &one, sizeof(one));
if (r < 0) {
r = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to set IP_MULTICAST_LOOP: %m");
goto fail;
}
r = setsockopt(m->llmnr_ipv4_udp_fd, IPPROTO_IP, IP_PKTINFO, &one, sizeof(one));
if (r < 0) {
r = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to set IP_PKTINFO: %m");
goto fail;
}
r = setsockopt(m->llmnr_ipv4_udp_fd, IPPROTO_IP, IP_RECVTTL, &one, sizeof(one));
if (r < 0) {
r = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to set IP_RECVTTL: %m");
goto fail;
}
/* Disable Don't-Fragment bit in the IP header */
r = setsockopt(m->llmnr_ipv4_udp_fd, IPPROTO_IP, IP_MTU_DISCOVER, &pmtu, sizeof(pmtu));
if (r < 0) {
r = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to set IP_MTU_DISCOVER: %m");
goto fail;
}
/* first try to bind without SO_REUSEADDR to detect another LLMNR responder */
r = bind(m->llmnr_ipv4_udp_fd, &sa.sa, sizeof(sa.in));
if (r < 0) {
if (errno != EADDRINUSE) {
r = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to bind socket: %m");
goto fail;
}
log_warning("LLMNR-IPv4(UDP): There appears to be another LLMNR responder running, or previously systemd-resolved crashed with some outstanding transfers.");
/* try again with SO_REUSEADDR */
r = setsockopt(m->llmnr_ipv4_udp_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
if (r < 0) {
r = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to set SO_REUSEADDR: %m");
goto fail;
}
r = bind(m->llmnr_ipv4_udp_fd, &sa.sa, sizeof(sa.in));
if (r < 0) {
r = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to bind socket: %m");
goto fail;
}
} else {
/* enable SO_REUSEADDR for the case that the user really wants multiple LLMNR responders */
r = setsockopt(m->llmnr_ipv4_udp_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
if (r < 0) {
r = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to set SO_REUSEADDR: %m");
goto fail;
}
}
r = sd_event_add_io(m->event, &m->llmnr_ipv4_udp_event_source, m->llmnr_ipv4_udp_fd, EPOLLIN, on_llmnr_packet, m);
if (r < 0)
goto fail;
(void) sd_event_source_set_description(m->llmnr_ipv4_udp_event_source, "llmnr-ipv4-udp");
return m->llmnr_ipv4_udp_fd;
fail:
m->llmnr_ipv4_udp_fd = safe_close(m->llmnr_ipv4_udp_fd);
return r;
}
int manager_llmnr_ipv6_udp_fd(Manager *m) {
union sockaddr_union sa = {
.in6.sin6_family = AF_INET6,
.in6.sin6_port = htobe16(LLMNR_PORT),
};
static const int one = 1, ttl = 255;
int r;
assert(m);
if (m->llmnr_ipv6_udp_fd >= 0)
return m->llmnr_ipv6_udp_fd;
m->llmnr_ipv6_udp_fd = socket(AF_INET6, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
if (m->llmnr_ipv6_udp_fd < 0)
return log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to create socket: %m");
r = setsockopt(m->llmnr_ipv6_udp_fd, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &ttl, sizeof(ttl));
if (r < 0) {
r = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to set IPV6_UNICAST_HOPS: %m");
goto fail;
}
/* RFC 4795, section 2.5 recommends setting the TTL of UDP packets to 255. */
r = setsockopt(m->llmnr_ipv6_udp_fd, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &ttl, sizeof(ttl));
if (r < 0) {
r = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to set IPV6_MULTICAST_HOPS: %m");
goto fail;
}
r = setsockopt(m->llmnr_ipv6_udp_fd, IPPROTO_IPV6, IPV6_MULTICAST_LOOP, &one, sizeof(one));
if (r < 0) {
r = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to set IPV6_MULTICAST_LOOP: %m");
goto fail;
}
r = setsockopt(m->llmnr_ipv6_udp_fd, IPPROTO_IPV6, IPV6_V6ONLY, &one, sizeof(one));
if (r < 0) {
r = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to set IPV6_V6ONLY: %m");
goto fail;
}
r = setsockopt(m->llmnr_ipv6_udp_fd, IPPROTO_IPV6, IPV6_RECVPKTINFO, &one, sizeof(one));
if (r < 0) {
r = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to set IPV6_RECVPKTINFO: %m");
goto fail;
}
r = setsockopt(m->llmnr_ipv6_udp_fd, IPPROTO_IPV6, IPV6_RECVHOPLIMIT, &one, sizeof(one));
if (r < 0) {
r = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to set IPV6_RECVHOPLIMIT: %m");
goto fail;
}
/* first try to bind without SO_REUSEADDR to detect another LLMNR responder */
r = bind(m->llmnr_ipv6_udp_fd, &sa.sa, sizeof(sa.in6));
if (r < 0) {
if (errno != EADDRINUSE) {
r = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to bind socket: %m");
goto fail;
}
log_warning("LLMNR-IPv6(UDP): There appears to be another LLMNR responder running, or previously systemd-resolved crashed with some outstanding transfers.");
/* try again with SO_REUSEADDR */
r = setsockopt(m->llmnr_ipv6_udp_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
if (r < 0) {
r = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to set SO_REUSEADDR: %m");
goto fail;
}
r = bind(m->llmnr_ipv6_udp_fd, &sa.sa, sizeof(sa.in6));
if (r < 0) {
r = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to bind socket: %m");
goto fail;
}
} else {
/* enable SO_REUSEADDR for the case that the user really wants multiple LLMNR responders */
r = setsockopt(m->llmnr_ipv6_udp_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
if (r < 0) {
r = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to set SO_REUSEADDR: %m");
goto fail;
}
}
r = sd_event_add_io(m->event, &m->llmnr_ipv6_udp_event_source, m->llmnr_ipv6_udp_fd, EPOLLIN, on_llmnr_packet, m);
if (r < 0)
goto fail;
(void) sd_event_source_set_description(m->llmnr_ipv6_udp_event_source, "llmnr-ipv6-udp");
return m->llmnr_ipv6_udp_fd;
fail:
m->llmnr_ipv6_udp_fd = safe_close(m->llmnr_ipv6_udp_fd);
return r;
}
static int on_llmnr_stream_packet(DnsStream *s) {
DnsScope *scope;
assert(s);
assert(s->read_packet);
scope = manager_find_scope(s->manager, s->read_packet);
if (!scope)
log_debug("Got LLMNR TCP packet on unknown scope. Ignoring.");
else if (dns_packet_validate_query(s->read_packet) > 0) {
log_debug("Got LLMNR TCP query packet for id %u", DNS_PACKET_ID(s->read_packet));
dns_scope_process_query(scope, s, s->read_packet);
} else
log_debug("Invalid LLMNR TCP packet, ignoring.");
dns_stream_unref(s);
return 0;
}
static int on_llmnr_stream(sd_event_source *s, int fd, uint32_t revents, void *userdata) {
DnsStream *stream;
Manager *m = userdata;
int cfd, r;
cfd = accept4(fd, NULL, NULL, SOCK_NONBLOCK|SOCK_CLOEXEC);
if (cfd < 0) {
if (IN_SET(errno, EAGAIN, EINTR))
return 0;
return -errno;
}
r = dns_stream_new(m, &stream, DNS_PROTOCOL_LLMNR, cfd);
if (r < 0) {
safe_close(cfd);
return r;
}
stream->on_packet = on_llmnr_stream_packet;
return 0;
}
int manager_llmnr_ipv4_tcp_fd(Manager *m) {
union sockaddr_union sa = {
.in.sin_family = AF_INET,
.in.sin_port = htobe16(LLMNR_PORT),
};
static const int one = 1, pmtu = IP_PMTUDISC_DONT;
int r;
assert(m);
if (m->llmnr_ipv4_tcp_fd >= 0)
return m->llmnr_ipv4_tcp_fd;
m->llmnr_ipv4_tcp_fd = socket(AF_INET, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
if (m->llmnr_ipv4_tcp_fd < 0)
return log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to create socket: %m");
/* RFC 4795, section 2.5. requires setting the TTL of TCP streams to 1 */
r = setsockopt(m->llmnr_ipv4_tcp_fd, IPPROTO_IP, IP_TTL, &one, sizeof(one));
if (r < 0) {
r = log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to set IP_TTL: %m");
goto fail;
}
r = setsockopt(m->llmnr_ipv4_tcp_fd, IPPROTO_IP, IP_PKTINFO, &one, sizeof(one));
if (r < 0) {
r = log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to set IP_PKTINFO: %m");
goto fail;
}
r = setsockopt(m->llmnr_ipv4_tcp_fd, IPPROTO_IP, IP_RECVTTL, &one, sizeof(one));
if (r < 0) {
r = log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to set IP_RECVTTL: %m");
goto fail;
}
/* Disable Don't-Fragment bit in the IP header */
r = setsockopt(m->llmnr_ipv4_tcp_fd, IPPROTO_IP, IP_MTU_DISCOVER, &pmtu, sizeof(pmtu));
if (r < 0) {
r = log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to set IP_MTU_DISCOVER: %m");
goto fail;
}
/* first try to bind without SO_REUSEADDR to detect another LLMNR responder */
r = bind(m->llmnr_ipv4_tcp_fd, &sa.sa, sizeof(sa.in));
if (r < 0) {
if (errno != EADDRINUSE) {
r = log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to bind socket: %m");
goto fail;
}
log_warning("LLMNR-IPv4(TCP): There appears to be another LLMNR responder running, or previously systemd-resolved crashed with some outstanding transfers.");
/* try again with SO_REUSEADDR */
r = setsockopt(m->llmnr_ipv4_tcp_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
if (r < 0) {
r = log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to set SO_REUSEADDR: %m");
goto fail;
}
r = bind(m->llmnr_ipv4_tcp_fd, &sa.sa, sizeof(sa.in));
if (r < 0) {
r = log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to bind socket: %m");
goto fail;
}
} else {
/* enable SO_REUSEADDR for the case that the user really wants multiple LLMNR responders */
r = setsockopt(m->llmnr_ipv4_tcp_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
if (r < 0) {
r = log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to set SO_REUSEADDR: %m");
goto fail;
}
}
r = listen(m->llmnr_ipv4_tcp_fd, SOMAXCONN);
if (r < 0) {
r = log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to listen the stream: %m");
goto fail;
}
r = sd_event_add_io(m->event, &m->llmnr_ipv4_tcp_event_source, m->llmnr_ipv4_tcp_fd, EPOLLIN, on_llmnr_stream, m);
if (r < 0)
goto fail;
(void) sd_event_source_set_description(m->llmnr_ipv4_tcp_event_source, "llmnr-ipv4-tcp");
return m->llmnr_ipv4_tcp_fd;
fail:
m->llmnr_ipv4_tcp_fd = safe_close(m->llmnr_ipv4_tcp_fd);
return r;
}
int manager_llmnr_ipv6_tcp_fd(Manager *m) {
union sockaddr_union sa = {
.in6.sin6_family = AF_INET6,
.in6.sin6_port = htobe16(LLMNR_PORT),
};
static const int one = 1;
int r;
assert(m);
if (m->llmnr_ipv6_tcp_fd >= 0)
return m->llmnr_ipv6_tcp_fd;
m->llmnr_ipv6_tcp_fd = socket(AF_INET6, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
if (m->llmnr_ipv6_tcp_fd < 0)
return log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to create socket: %m");
/* RFC 4795, section 2.5. requires setting the TTL of TCP streams to 1 */
r = setsockopt(m->llmnr_ipv6_tcp_fd, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &one, sizeof(one));
if (r < 0) {
r = log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to set IPV6_UNICAST_HOPS: %m");
goto fail;
}
r = setsockopt(m->llmnr_ipv6_tcp_fd, IPPROTO_IPV6, IPV6_V6ONLY, &one, sizeof(one));
if (r < 0) {
r = log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to set IPV6_V6ONLY: %m");
goto fail;
}
r = setsockopt(m->llmnr_ipv6_tcp_fd, IPPROTO_IPV6, IPV6_RECVPKTINFO, &one, sizeof(one));
if (r < 0) {
r = log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to set IPV6_RECVPKTINFO: %m");
goto fail;
}
r = setsockopt(m->llmnr_ipv6_tcp_fd, IPPROTO_IPV6, IPV6_RECVHOPLIMIT, &one, sizeof(one));
if (r < 0) {
r = log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to set IPV6_RECVHOPLIMIT: %m");
goto fail;
}
/* first try to bind without SO_REUSEADDR to detect another LLMNR responder */
r = bind(m->llmnr_ipv6_tcp_fd, &sa.sa, sizeof(sa.in6));
if (r < 0) {
if (errno != EADDRINUSE) {
r = log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to bind socket: %m");
goto fail;
}
log_warning("LLMNR-IPv6(TCP): There appears to be another LLMNR responder running, or previously systemd-resolved crashed with some outstanding transfers.");
/* try again with SO_REUSEADDR */
r = setsockopt(m->llmnr_ipv6_tcp_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
if (r < 0) {
r = log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to set SO_REUSEADDR: %m");
goto fail;
}
r = bind(m->llmnr_ipv6_tcp_fd, &sa.sa, sizeof(sa.in6));
if (r < 0) {
r = log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to bind socket: %m");
goto fail;
}
} else {
/* enable SO_REUSEADDR for the case that the user really wants multiple LLMNR responders */
r = setsockopt(m->llmnr_ipv6_tcp_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
if (r < 0) {
r = log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to set SO_REUSEADDR: %m");
goto fail;
}
}
r = listen(m->llmnr_ipv6_tcp_fd, SOMAXCONN);
if (r < 0) {
r = log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to listen the stream: %m");
goto fail;
}
r = sd_event_add_io(m->event, &m->llmnr_ipv6_tcp_event_source, m->llmnr_ipv6_tcp_fd, EPOLLIN, on_llmnr_stream, m);
if (r < 0)
goto fail;
(void) sd_event_source_set_description(m->llmnr_ipv6_tcp_event_source, "llmnr-ipv6-tcp");
return m->llmnr_ipv6_tcp_fd;
fail:
m->llmnr_ipv6_tcp_fd = safe_close(m->llmnr_ipv6_tcp_fd);
return r;
}
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