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resolved: unify the two functions to create extra stubs

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There is a minor functional change:
IPV6_FREEBIND is set of IPv6 sockets, not IP_FREEBIND. This was missed in
af8b1384, but I noticed only after the merging the two functions.

And a not-so-minor functional chagnge:
7216a3b5dc changed manager_dns_stub_tcp_fd_extra() to return the fd even
if the source was already initialized, but it didn't do the same change for
manager_dns_stub_udp_fd_extra(), so it would return 0 in that case. But
0354029bf5 uses manager_dns_stub_udp_fd_extra() when preparing to call
manager_send(), and will pass 0 as the fd in that case. For both socket types
fd is now always returned.
This commit is contained in:
Zbigniew Jędrzejewski-Szmek
2020-09-10 00:44:53 +02:00
parent e4bed40f40
commit b5febb3f56
1 changed files with 46 additions and 100 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/resolve/resolved-dns-stub.c
+46 -100
View File
@@ -15,7 +15,7 @@
* IP and UDP header sizes */
#define ADVERTISE_DATAGRAM_SIZE_MAX (65536U-14U-20U-8U)
static int manager_dns_stub_udp_fd_extra(Manager *m, DnsStubListenerExtra *l);
static int manager_dns_stub_fd_extra(Manager *m, DnsStubListenerExtra *l, int type);
static void dns_stub_listener_extra_hash_func(const DnsStubListenerExtra *a, struct siphash *state) {
assert(a);
@@ -217,7 +217,7 @@ static int dns_stub_send(
* is because otherwise the kernel will choose it automatically based on the routing table and will
* thus pick 127.0.0.1 rather than 127.0.0.53. */
r = manager_send(m,
manager_dns_stub_udp_fd_extra(m, l),
manager_dns_stub_fd_extra(m, l, SOCK_DGRAM),
l ? p->ifindex : LOOPBACK_IFINDEX, /* force loopback iface if this is the main listener stub */
p->family, &p->sender, p->sender_port, &p->destination,
reply);
@@ -605,19 +605,25 @@ static int manager_dns_stub_udp_fd(Manager *m) {
return TAKE_FD(fd);
}
static int manager_dns_stub_udp_fd_extra(Manager *m, DnsStubListenerExtra *l) {
static int manager_dns_stub_fd_extra(Manager *m, DnsStubListenerExtra *l, int type) {
_cleanup_free_ char *pretty = NULL;
_cleanup_close_ int fd = -1;
union sockaddr_union sa;
int r;
assert(m);
assert(IN_SET(type, SOCK_DGRAM, SOCK_STREAM));
if (!l)
return manager_dns_stub_udp_fd(m);
if (!l) {
if (type == SOCK_DGRAM)
return manager_dns_stub_udp_fd(m);
else
return manager_dns_stub_tcp_fd(m);
}
if (l->udp_event_source)
return 0;
sd_event_source **event_source = type == SOCK_DGRAM ? &l->udp_event_source : &l->tcp_event_source;
if (*event_source)
return sd_event_source_get_io_fd(*event_source);
if (l->family == AF_INET)
sa = (union sockaddr_union) {
@@ -632,40 +638,55 @@ static int manager_dns_stub_udp_fd_extra(Manager *m, DnsStubListenerExtra *l) {
.in6.sin6_addr = l->address.in6,
};
fd = socket(l->family, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
fd = socket(l->family, type | SOCK_CLOEXEC | SOCK_NONBLOCK, 0);
if (fd < 0) {
r = -errno;
goto fail;
}
if (l->family == AF_INET) {
r = setsockopt_int(fd, IPPROTO_IP, IP_FREEBIND, true);
if (r < 0)
goto fail;
}
r = set_dns_stub_common_socket_options(fd, l->family);
if (r < 0)
goto fail;
/* Do not set IP_TTL for extra DNS stub listners, as the address may not be local and in that case
* people may want ttl > 1. */
if (l->family == AF_INET)
r = setsockopt_int(fd, IPPROTO_IP, IP_FREEBIND, true);
else
r = setsockopt_int(fd, IPPROTO_IPV6, IPV6_FREEBIND, true);
if (r < 0)
goto fail;
if (bind(fd, &sa.sa, SOCKADDR_LEN(sa)) < 0) {
r = -errno;
goto fail;
}
r = sd_event_add_io(m->event, &l->udp_event_source, fd, EPOLLIN, on_dns_stub_packet_extra, l);
if (type == SOCK_STREAM &&
listen(fd, SOMAXCONN) < 0) {
r = -errno;
goto fail;
}
r = sd_event_add_io(m->event, event_source, fd, EPOLLIN,
type == SOCK_DGRAM ? on_dns_stub_packet_extra : on_dns_stub_stream_extra,
l);
if (r < 0)
goto fail;
r = sd_event_source_set_io_fd_own(l->udp_event_source, true);
r = sd_event_source_set_io_fd_own(*event_source, true);
if (r < 0)
goto fail;
(void) sd_event_source_set_description(l->udp_event_source, "dns-stub-udp-extra");
(void) sd_event_source_set_description(*event_source,
type == SOCK_DGRAM ? "dns-stub-udp-extra" : "dns-stub-tcp-extra");
if (DEBUG_LOGGING) {
(void) in_addr_port_to_string(l->family, &l->address, l->port, &pretty);
log_debug("Listening on UDP socket %s.", strnull(pretty));
log_debug("Listening on %s socket %s.",
type == SOCK_DGRAM ? "UDP" : "TCP",
strnull(pretty));
}
return TAKE_FD(fd);
@@ -673,9 +694,11 @@ static int manager_dns_stub_udp_fd_extra(Manager *m, DnsStubListenerExtra *l) {
fail:
assert(r < 0);
(void) in_addr_port_to_string(l->family, &l->address, l->port, &pretty);
if (r == -EADDRINUSE)
return log_warning_errno(r, "Another process is already listening on UDP socket %s: %m", strnull(pretty));
return log_warning_errno(r, "Failed to listen on UDP socket %s: %m", strnull(pretty));
return log_warning_errno(r,
r == -EADDRINUSE ? "Another process is already listening on %s socket %s: %m" :
"Failed to listen on %s socket %s: %m",
type == SOCK_DGRAM ? "UDP" : "TCP",
strnull(pretty));
}
static int manager_dns_stub_tcp_fd(Manager *m) {
@@ -726,83 +749,6 @@ static int manager_dns_stub_tcp_fd(Manager *m) {
return TAKE_FD(fd);
}
static int manager_dns_stub_tcp_fd_extra(Manager *m, DnsStubListenerExtra *l) {
_cleanup_free_ char *pretty = NULL;
_cleanup_close_ int fd = -1;
union sockaddr_union sa;
int r;
if (l->tcp_event_source)
return sd_event_source_get_io_fd(l->tcp_event_source);;
if (l->family == AF_INET)
sa = (union sockaddr_union) {
.in.sin_family = l->family,
.in.sin_port = htobe16(l->port != 0 ? l->port : 53U),
.in.sin_addr = l->address.in,
};
else
sa = (union sockaddr_union) {
.in6.sin6_family = l->family,
.in6.sin6_port = htobe16(l->port != 0 ? l->port : 53U),
.in6.sin6_addr = l->address.in6,
};
fd = socket(l->family, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
if (fd < 0) {
r = -errno;
goto fail;
}
r = set_dns_stub_common_socket_options(fd, l->family);
if (r < 0)
goto fail;
/* Do not set IP_TTL for extra DNS stub listners, as the address may not be local and in that
* case people may want ttl > 1. */
if (l->family == AF_INET)
r = setsockopt_int(fd, IPPROTO_IP, IP_FREEBIND, true);
else
r = setsockopt_int(fd, IPPROTO_IPV6, IPV6_FREEBIND, true);
if (r < 0)
goto fail;
if (bind(fd, &sa.sa, SOCKADDR_LEN(sa)) < 0) {
r = -errno;
goto fail;
}
if (listen(fd, SOMAXCONN) < 0) {
r = -errno;
goto fail;
}
r = sd_event_add_io(m->event, &l->tcp_event_source, fd, EPOLLIN, on_dns_stub_stream_extra, l);
if (r < 0)
goto fail;
r = sd_event_source_set_io_fd_own(l->tcp_event_source, true);
if (r < 0)
goto fail;
(void) sd_event_source_set_description(l->tcp_event_source, "dns-stub-tcp-extra");
if (DEBUG_LOGGING) {
(void) in_addr_port_to_string(l->family, &l->address, l->port, &pretty);
log_debug("Listening on TCP socket %s.", strnull(pretty));
}
return TAKE_FD(fd);
fail:
assert(r < 0);
(void) in_addr_port_to_string(l->family, &l->address, l->port, &pretty);
if (r == -EADDRINUSE)
return log_warning_errno(r, "Another process is already listening on TCP socket %s: %m", strnull(pretty));
return log_warning_errno(r, "Failed to listen on TCP socket %s: %m", strnull(pretty));
}
int manager_dns_stub_start(Manager *m) {
const char *t = "UDP";
int r = 0;
@@ -846,9 +792,9 @@ int manager_dns_stub_start(Manager *m) {
ORDERED_SET_FOREACH(l, m->dns_extra_stub_listeners) {
if (FLAGS_SET(l->mode, DNS_STUB_LISTENER_UDP))
(void) manager_dns_stub_udp_fd_extra(m, l);
(void) manager_dns_stub_fd_extra(m, l, SOCK_DGRAM);
if (FLAGS_SET(l->mode, DNS_STUB_LISTENER_TCP))
(void) manager_dns_stub_tcp_fd_extra(m, l);
(void) manager_dns_stub_fd_extra(m, l, SOCK_STREAM);
}
}