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authorLennart Poettering <lennart@poettering.net>2014-07-29 23:51:34 +0200
committerLennart Poettering <lennart@poettering.net>2014-07-29 23:53:08 +0200
commitbf3f1271e2cc0c22b11c8a805a997578dabe9191 (patch)
treeecab14a27b61874883630fd2388f408078a83b8e
parent088b6ba2648db1899fd956bf8238f0706fbe6c45 (diff)
resolved: set LLMNR TCP and UDP TTLs to the values suggested by the RFC
-rw-r--r--src/resolve/resolved-dns-scope.c2
-rw-r--r--src/resolve/resolved-manager.c16
2 files changed, 11 insertions, 7 deletions
diff --git a/src/resolve/resolved-dns-scope.c b/src/resolve/resolved-dns-scope.c
index b226f5a457..5742f3ef47 100644
--- a/src/resolve/resolved-dns-scope.c
+++ b/src/resolve/resolved-dns-scope.c
@@ -254,7 +254,7 @@ int dns_scope_tcp_socket(DnsScope *s, int family, const union in_addr_union *add
}
if (s->protocol == DNS_PROTOCOL_LLMNR) {
- /* RFC 4795, section 2.5 suggests the TTL to be set to 1 */
+ /* RFC 4795, section 2.5 requires the TTL to be set to 1 */
if (sa.sa.sa_family == AF_INET) {
r = setsockopt(fd, IPPROTO_IP, IP_TTL, &one, sizeof(one));
diff --git a/src/resolve/resolved-manager.c b/src/resolve/resolved-manager.c
index a8715bd5bf..523ed20208 100644
--- a/src/resolve/resolved-manager.c
+++ b/src/resolve/resolved-manager.c
@@ -1024,7 +1024,7 @@ int manager_llmnr_ipv4_udp_fd(Manager *m) {
.in.sin_family = AF_INET,
.in.sin_port = htobe16(5355),
};
- static const int one = 1, pmtu = IP_PMTUDISC_DONT;
+ static const int one = 1, pmtu = IP_PMTUDISC_DONT, ttl = 255;
int r;
assert(m);
@@ -1036,13 +1036,14 @@ int manager_llmnr_ipv4_udp_fd(Manager *m) {
if (m->llmnr_ipv4_udp_fd < 0)
return -errno;
- r = setsockopt(m->llmnr_ipv4_udp_fd, IPPROTO_IP, IP_TTL, &one, sizeof(one));
+ /* 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 = -errno;
goto fail;
}
- r = setsockopt(m->llmnr_ipv4_udp_fd, IPPROTO_IP, IP_MULTICAST_TTL, &one, sizeof(one));
+ r = setsockopt(m->llmnr_ipv4_udp_fd, IPPROTO_IP, IP_MULTICAST_TTL, &ttl, sizeof(ttl));
if (r < 0) {
r = -errno;
goto fail;
@@ -1101,7 +1102,7 @@ int manager_llmnr_ipv6_udp_fd(Manager *m) {
.in6.sin6_family = AF_INET6,
.in6.sin6_port = htobe16(5355),
};
- static const int one = 1;
+ static const int one = 1, ttl = 255;
int r;
assert(m);
@@ -1113,13 +1114,14 @@ int manager_llmnr_ipv6_udp_fd(Manager *m) {
if (m->llmnr_ipv6_udp_fd < 0)
return -errno;
- r = setsockopt(m->llmnr_ipv6_udp_fd, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &one, sizeof(one));
+ r = setsockopt(m->llmnr_ipv6_udp_fd, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &ttl, sizeof(ttl));
if (r < 0) {
r = -errno;
goto fail;
}
- r = setsockopt(m->llmnr_ipv6_udp_fd, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &one, sizeof(one));
+ /* 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 = -errno;
goto fail;
@@ -1243,6 +1245,7 @@ int manager_llmnr_ipv4_tcp_fd(Manager *m) {
if (m->llmnr_ipv4_tcp_fd < 0)
return -errno;
+ /* 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 = -errno;
@@ -1314,6 +1317,7 @@ int manager_llmnr_ipv6_tcp_fd(Manager *m) {
if (m->llmnr_ipv6_tcp_fd < 0)
return -errno;
+ /* 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 = -errno;