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resolved: unify the two functions to create main stubs

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There is a small functional difference: IP_TTL==1 is now also set for the UDP
socket. I assume that it wasn't set by mistake.
This commit is contained in:
Zbigniew Jędrzejewski-Szmek
2020-09-10 00:46:44 +02:00
parent b5febb3f56
commit d491917c9f
1 changed files with 32 additions and 72 deletions
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src/resolve/resolved-dns-stub.c
+32 -72
View File
@@ -564,19 +564,22 @@ static int set_dns_stub_common_socket_options(int fd, int family) {
return 0;
}
static int manager_dns_stub_udp_fd(Manager *m) {
static int manager_dns_stub_fd(Manager *m, int type) {
union sockaddr_union sa = {
.in.sin_family = AF_INET,
.in.sin_port = htobe16(53),
.in.sin_addr.s_addr = htobe32(INADDR_DNS_STUB),
.in.sin_port = htobe16(53),
};
_cleanup_close_ int fd = -1;
int r;
if (m->dns_stub_udp_event_source)
return sd_event_source_get_io_fd(m->dns_stub_udp_event_source);
assert(IN_SET(type, SOCK_DGRAM, SOCK_STREAM));
fd = socket(AF_INET, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
sd_event_source **event_source = type == SOCK_DGRAM ? &m->dns_stub_udp_event_source : &m->dns_stub_tcp_event_source;
if (*event_source)
return sd_event_source_get_io_fd(*event_source);
fd = socket(AF_INET, type | SOCK_CLOEXEC | SOCK_NONBLOCK, 0);
if (fd < 0)
return -errno;
@@ -589,18 +592,29 @@ static int manager_dns_stub_udp_fd(Manager *m) {
if (r < 0)
return r;
r = setsockopt_int(fd, IPPROTO_IP, IP_TTL, 1);
if (r < 0)
return r;
if (bind(fd, &sa.sa, sizeof(sa.in)) < 0)
return -errno;
r = sd_event_add_io(m->event, &m->dns_stub_udp_event_source, fd, EPOLLIN, on_dns_stub_packet, m);
if (type == SOCK_STREAM &&
listen(fd, SOMAXCONN) < 0)
return -errno;
r = sd_event_add_io(m->event, event_source, fd, EPOLLIN,
type == SOCK_DGRAM ? on_dns_stub_packet : on_dns_stub_stream,
m);
if (r < 0)
return r;
r = sd_event_source_set_io_fd_own(m->dns_stub_udp_event_source, true);
r = sd_event_source_set_io_fd_own(*event_source, true);
if (r < 0)
return r;
(void) sd_event_source_set_description(m->dns_stub_udp_event_source, "dns-stub-udp");
(void) sd_event_source_set_description(*event_source,
type == SOCK_DGRAM ? "dns-stub-udp" : "dns-stub-tcp");
return TAKE_FD(fd);
}
@@ -614,12 +628,8 @@ static int manager_dns_stub_fd_extra(Manager *m, DnsStubListenerExtra *l, int ty
assert(m);
assert(IN_SET(type, SOCK_DGRAM, SOCK_STREAM));
if (!l) {
if (type == SOCK_DGRAM)
return manager_dns_stub_udp_fd(m);
else
return manager_dns_stub_tcp_fd(m);
}
if (!l)
return manager_dns_stub_fd(m, type);
sd_event_source **event_source = type == SOCK_DGRAM ? &l->udp_event_source : &l->tcp_event_source;
if (*event_source)
@@ -701,54 +711,6 @@ fail:
strnull(pretty));
}
static int manager_dns_stub_tcp_fd(Manager *m) {
union sockaddr_union sa = {
.in.sin_family = AF_INET,
.in.sin_addr.s_addr = htobe32(INADDR_DNS_STUB),
.in.sin_port = htobe16(53),
};
_cleanup_close_ int fd = -1;
int r;
if (m->dns_stub_tcp_event_source)
return sd_event_source_get_io_fd(m->dns_stub_tcp_event_source);
fd = socket(AF_INET, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
if (fd < 0)
return -errno;
r = set_dns_stub_common_socket_options(fd, AF_INET);
if (r < 0)
return r;
r = setsockopt_int(fd, IPPROTO_IP, IP_TTL, 1);
if (r < 0)
return r;
/* Make sure no traffic from outside the local host can leak to onto this socket */
r = socket_bind_to_ifindex(fd, LOOPBACK_IFINDEX);
if (r < 0)
return r;
if (bind(fd, &sa.sa, sizeof(sa.in)) < 0)
return -errno;
if (listen(fd, SOMAXCONN) < 0)
return -errno;
r = sd_event_add_io(m->event, &m->dns_stub_tcp_event_source, fd, EPOLLIN, on_dns_stub_stream, m);
if (r < 0)
return r;
r = sd_event_source_set_io_fd_own(m->dns_stub_tcp_event_source, true);
if (r < 0)
return r;
(void) sd_event_source_set_description(m->dns_stub_tcp_event_source, "dns-stub-tcp");
return TAKE_FD(fd);
}
int manager_dns_stub_start(Manager *m) {
const char *t = "UDP";
int r = 0;
@@ -764,23 +726,21 @@ int manager_dns_stub_start(Manager *m) {
"UDP/TCP");
if (FLAGS_SET(m->dns_stub_listener_mode, DNS_STUB_LISTENER_UDP))
r = manager_dns_stub_udp_fd(m);
r = manager_dns_stub_fd(m, SOCK_DGRAM);
if (r >= 0 &&
FLAGS_SET(m->dns_stub_listener_mode, DNS_STUB_LISTENER_TCP)) {
t = "TCP";
r = manager_dns_stub_tcp_fd(m);
r = manager_dns_stub_fd(m, SOCK_STREAM);
}
if (IN_SET(r, -EADDRINUSE, -EPERM)) {
if (r == -EADDRINUSE)
log_warning_errno(r,
"Another process is already listening on %s socket 127.0.0.53:53.\n"
"Turning off local DNS stub support.", t);
else
log_warning_errno(r,
"Failed to listen on %s socket 127.0.0.53:53: %m.\n"
"Turning off local DNS stub support.", t);
log_warning_errno(r,
r == -EADDRINUSE ? "Another process is already listening on %s socket 127.0.0.53:53.\n"
"Turning off local DNS stub support." :
"Failed to listen on %s socket 127.0.0.53:53: %m.\n"
"Turning off local DNS stub support.",
t);
manager_dns_stub_stop(m);
} else if (r < 0)
return log_error_errno(r, "Failed to listen on %s socket 127.0.0.53:53: %m", t);