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resolved: also use TCP tweaks on LLMNR (plus unify setsockopt() code)

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This commit is contained in:
Lennart Poettering
2021-02-17 21:12:53 +01:00
parent 8624f1286a
commit b850e51320
1 changed files with 65 additions and 39 deletions
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src/resolve/resolved-llmnr.c
+65 -39
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@@ -1,6 +1,7 @@
/* SPDX-License-Identifier: LGPL-2.1-or-later */
#include <netinet/in.h>
#include <netinet/tcp.h>
#include <resolv.h>
#include "errno-util.h"
@@ -111,6 +112,31 @@ static int on_llmnr_packet(sd_event_source *s, int fd, uint32_t revents, void *u
return 0;
}
static int set_llmnr_common_socket_options(int fd, int family) {
int r;
r = socket_set_recvpktinfo(fd, family, true);
if (r < 0)
return r;
r = socket_set_recvttl(fd, family, true);
if (r < 0)
return r;
return 0;
}
static int set_llmnr_common_udp_socket_options(int fd, int family) {
int r;
/* RFC 4795, section 2.5 recommends setting the TTL of UDP packets to 255. */
r = socket_set_ttl(fd, family, 255);
if (r < 0)
return r;
return 0;
}
int manager_llmnr_ipv4_udp_fd(Manager *m) {
union sockaddr_union sa = {
.in.sin_family = AF_INET,
@@ -128,10 +154,13 @@ int manager_llmnr_ipv4_udp_fd(Manager *m) {
if (s < 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_int(s, IPPROTO_IP, IP_TTL, 255);
r = set_llmnr_common_socket_options(s, AF_INET);
if (r < 0)
return log_error_errno(r, "LLMNR-IPv4(UDP): Failed to set IP_TTL: %m");
return log_error_errno(r, "LLMNR-IPv4(UDP): Failed to set common socket options: %m");
r = set_llmnr_common_udp_socket_options(s, AF_INET);
if (r < 0)
return log_error_errno(r, "LLMNR-IPv4(UDP): Failed to set common UDP socket options: %m");
r = setsockopt_int(s, IPPROTO_IP, IP_MULTICAST_TTL, 255);
if (r < 0)
@@ -141,14 +170,6 @@ int manager_llmnr_ipv4_udp_fd(Manager *m) {
if (r < 0)
return log_error_errno(r, "LLMNR-IPv4(UDP): Failed to set IP_MULTICAST_LOOP: %m");
r = setsockopt_int(s, IPPROTO_IP, IP_PKTINFO, true);
if (r < 0)
return log_error_errno(r, "LLMNR-IPv4(UDP): Failed to set IP_PKTINFO: %m");
r = setsockopt_int(s, IPPROTO_IP, IP_RECVTTL, true);
if (r < 0)
return log_error_errno(r, "LLMNR-IPv4(UDP): Failed to set IP_RECVTTL: %m");
/* Disable Don't-Fragment bit in the IP header */
r = setsockopt_int(s, IPPROTO_IP, IP_MTU_DISCOVER, IP_PMTUDISC_DONT);
if (r < 0)
@@ -203,9 +224,13 @@ int manager_llmnr_ipv6_udp_fd(Manager *m) {
if (s < 0)
return log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to create socket: %m");
r = setsockopt_int(s, IPPROTO_IPV6, IPV6_UNICAST_HOPS, 255);
r = set_llmnr_common_socket_options(s, AF_INET6);
if (r < 0)
return log_error_errno(r, "LLMNR-IPv6(UDP): Failed to set IPV6_UNICAST_HOPS: %m");
return log_error_errno(r, "LLMNR-IPv6(UDP): Failed to set common socket options: %m");
r = set_llmnr_common_udp_socket_options(s, AF_INET6);
if (r < 0)
return log_error_errno(r, "LLMNR-IPv6(UDP): Failed to set common UDP socket options: %m");
/* RFC 4795, section 2.5 recommends setting the TTL of UDP packets to 255. */
r = setsockopt_int(s, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, 255);
@@ -220,14 +245,6 @@ int manager_llmnr_ipv6_udp_fd(Manager *m) {
if (r < 0)
return log_error_errno(r, "LLMNR-IPv6(UDP): Failed to set IPV6_V6ONLY: %m");
r = setsockopt_int(s, IPPROTO_IPV6, IPV6_RECVPKTINFO, true);
if (r < 0)
return log_error_errno(r, "LLMNR-IPv6(UDP): Failed to set IPV6_RECVPKTINFO: %m");
r = setsockopt_int(s, IPPROTO_IPV6, IPV6_RECVHOPLIMIT, true);
if (r < 0)
return log_error_errno(r, "LLMNR-IPv6(UDP): Failed to set IPV6_RECVHOPLIMIT: %m");
/* first try to bind without SO_REUSEADDR to detect another LLMNR responder */
r = bind(s, &sa.sa, sizeof(sa.in6));
if (r < 0) {
@@ -308,6 +325,25 @@ static int on_llmnr_stream(sd_event_source *s, int fd, uint32_t revents, void *u
return 0;
}
static int set_llmnr_common_tcp_socket_options(int fd, int family) {
int r;
/* RFC 4795, section 2.5. requires setting the TTL of TCP streams to 1 */
r = socket_set_ttl(fd, family, 1);
if (r < 0)
return r;
r = setsockopt_int(fd, IPPROTO_TCP, TCP_FASTOPEN, 5); /* Everybody appears to pick qlen=5, let's do the same here. */
if (r < 0)
log_debug_errno(r, "Failed to enable TCP_FASTOPEN on TCP listening socket, ignoring: %m");
r = setsockopt_int(fd, IPPROTO_TCP, TCP_NODELAY, true);
if (r < 0)
log_debug_errno(r, "Failed to enable TCP_NODELAY mode, ignoring: %m");
return 0;
}
int manager_llmnr_ipv4_tcp_fd(Manager *m) {
union sockaddr_union sa = {
.in.sin_family = AF_INET,
@@ -325,18 +361,13 @@ int manager_llmnr_ipv4_tcp_fd(Manager *m) {
if (s < 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_int(s, IPPROTO_IP, IP_TTL, 1);
r = set_llmnr_common_socket_options(s, AF_INET);
if (r < 0)
return log_error_errno(r, "LLMNR-IPv4(TCP): Failed to set IP_TTL: %m");
return log_error_errno(r, "LLMNR-IPv4(TCP): Failed to set common socket options: %m");
r = setsockopt_int(s, IPPROTO_IP, IP_PKTINFO, true);
r = set_llmnr_common_tcp_socket_options(s, AF_INET);
if (r < 0)
return log_error_errno(r, "LLMNR-IPv4(TCP): Failed to set IP_PKTINFO: %m");
r = setsockopt_int(s, IPPROTO_IP, IP_RECVTTL, true);
if (r < 0)
return log_error_errno(r, "LLMNR-IPv4(TCP): Failed to set IP_RECVTTL: %m");
return log_error_errno(r, "LLMNR-IPv4(TCP): Failed to set common TCP socket options: %m");
/* Disable Don't-Fragment bit in the IP header */
r = setsockopt_int(s, IPPROTO_IP, IP_MTU_DISCOVER, IP_PMTUDISC_DONT);
@@ -396,22 +427,17 @@ int manager_llmnr_ipv6_tcp_fd(Manager *m) {
if (s < 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_int(s, IPPROTO_IPV6, IPV6_UNICAST_HOPS, 1);
if (r < 0)
return log_error_errno(r, "LLMNR-IPv6(TCP): Failed to set IPV6_UNICAST_HOPS: %m");
r = setsockopt_int(s, IPPROTO_IPV6, IPV6_V6ONLY, true);
if (r < 0)
return log_error_errno(r, "LLMNR-IPv6(TCP): Failed to set IPV6_V6ONLY: %m");
r = setsockopt_int(s, IPPROTO_IPV6, IPV6_RECVPKTINFO, true);
r = set_llmnr_common_socket_options(s, AF_INET6);
if (r < 0)
return log_error_errno(r, "LLMNR-IPv6(TCP): Failed to set IPV6_RECVPKTINFO: %m");
return log_error_errno(r, "LLMNR-IPv6(TCP): Failed to set common socket options: %m");
r = setsockopt_int(s, IPPROTO_IPV6, IPV6_RECVHOPLIMIT, true);
r = set_llmnr_common_tcp_socket_options(s, AF_INET6);
if (r < 0)
return log_error_errno(r, "LLMNR-IPv6(TCP): Failed to set IPV6_RECVHOPLIMIT: %m");
return log_error_errno(r, "LLMNR-IPv6(TCP): Failed to set common TCP socket options: %m");
/* first try to bind without SO_REUSEADDR to detect another LLMNR responder */
r = bind(s, &sa.sa, sizeof(sa.in6));