From 5777c6130b2d0858df1fa9314e4e8c2441b7c1af Mon Sep 17 00:00:00 2001
From: Lennart Poettering <lennart@poettering.net>
Date: Wed, 28 Oct 2020 13:46:26 +0100
Subject: [PATCH] resolved: always take a timestamp when first seeing a packet

This is later useful if we want to adjust the TTLs of packets we want to
propagate to clients.
---
 src/resolve/resolved-dns-packet.h      | 1 +
 src/resolve/resolved-dns-stream.c      | 1 +
 src/resolve/resolved-dns-transaction.c | 5 +----
 src/resolve/resolved-manager.c         | 2 ++
 4 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/src/resolve/resolved-dns-packet.h b/src/resolve/resolved-dns-packet.h
index 0c804d6d2b..4dba96b3b8 100644
--- a/src/resolve/resolved-dns-packet.h
+++ b/src/resolve/resolved-dns-packet.h
@@ -71,6 +71,7 @@ struct DnsPacket {
         union in_addr_union sender, destination;
         uint16_t sender_port, destination_port;
         uint32_t ttl;
+        usec_t timestamp; /* CLOCK_BOOTTIME (or CLOCK_MONOTONIC if the former doesn't exist) */
 
         /* For support of truncated packets */
         DnsPacket *more;
diff --git a/src/resolve/resolved-dns-stream.c b/src/resolve/resolved-dns-stream.c
index 1aab089934..cf5057ddf0 100644
--- a/src/resolve/resolved-dns-stream.c
+++ b/src/resolve/resolved-dns-stream.c
@@ -377,6 +377,7 @@ static int on_stream_io(sd_event_source *es, int fd, uint32_t revents, void *use
                                         s->read_packet->family = s->peer.sa.sa_family;
                                         s->read_packet->ttl = s->ttl;
                                         s->read_packet->ifindex = s->ifindex;
+                                        s->read_packet->timestamp = now(clock_boottime_or_monotonic());
 
                                         if (s->read_packet->family == AF_INET) {
                                                 s->read_packet->sender.in = s->peer.in.sin_addr;
diff --git a/src/resolve/resolved-dns-transaction.c b/src/resolve/resolved-dns-transaction.c
index 60e8e94e63..b20a61a401 100644
--- a/src/resolve/resolved-dns-transaction.c
+++ b/src/resolve/resolved-dns-transaction.c
@@ -890,7 +890,6 @@ static int dns_transaction_fix_rcode(DnsTransaction *t) {
 }
 
 void dns_transaction_process_reply(DnsTransaction *t, DnsPacket *p) {
-        usec_t ts;
         int r;
 
         assert(t);
@@ -973,8 +972,6 @@ void dns_transaction_process_reply(DnsTransaction *t, DnsPacket *p) {
                 }
         }
 
-        assert_se(sd_event_now(t->scope->manager->event, clock_boottime_or_monotonic(), &ts) >= 0);
-
         switch (t->scope->protocol) {
 
         case DNS_PROTOCOL_DNS:
@@ -1039,7 +1036,7 @@ void dns_transaction_process_reply(DnsTransaction *t, DnsPacket *p) {
 
         case DNS_PROTOCOL_LLMNR:
         case DNS_PROTOCOL_MDNS:
-                dns_scope_packet_received(t->scope, ts - t->start_usec);
+                dns_scope_packet_received(t->scope, p->timestamp - t->start_usec);
                 break;
 
         default:
diff --git a/src/resolve/resolved-manager.c b/src/resolve/resolved-manager.c
index 81d043a3fa..cc68484169 100644
--- a/src/resolve/resolved-manager.c
+++ b/src/resolve/resolved-manager.c
@@ -854,6 +854,8 @@ int manager_recv(Manager *m, int fd, DnsProtocol protocol, DnsPacket **ret) {
         } else
                 return -EAFNOSUPPORT;
 
+        p->timestamp = now(clock_boottime_or_monotonic());
+
         CMSG_FOREACH(cmsg, &mh) {
 
                 if (cmsg->cmsg_level == IPPROTO_IPV6) {