From: Ronan Pigott <ronan@rjp.ie>
Date: Thu, 1 Aug 2024 17:59:12 +0000 (-0700)
Subject: resolved: don't treat conn reset as packet loss
X-Git-Tag: v257-rc1~774
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ddd710a355acc698b48159f3e501dda5a7dc2704;p=thirdparty%2Fsystemd.git

resolved: don't treat conn reset as packet loss

tcp reset / icmp port-unreachable are markedly different conditions than
packet loss. It doesn't make much sense to retry in this case. It's
actually not clear if there is any benefit at all retrying tcp
connections, which were presumably already retried as necessary by the
tcp stack.
---

diff --git a/src/resolve/resolved-dns-stream.c b/src/resolve/resolved-dns-stream.c
index 1a43d0bd498..8c1512006af 100644
--- a/src/resolve/resolved-dns-stream.c
+++ b/src/resolve/resolved-dns-stream.c
@@ -322,6 +322,12 @@ static int on_stream_io(sd_event_source *es, int fd, uint32_t revents, void *use
                         return dns_stream_complete(s, -r);
         }
 
+        if (revents & EPOLLERR) {
+                socklen_t errlen = sizeof(r);
+                if (getsockopt(s->fd, SOL_SOCKET, SO_ERROR, &r, &errlen) == 0)
+                        return dns_stream_complete(s, r);
+        }
+
         if ((revents & EPOLLOUT) &&
             s->write_packet &&
             s->n_written < sizeof(s->write_size) + s->write_packet->size) {
diff --git a/src/resolve/resolved-dns-transaction.c b/src/resolve/resolved-dns-transaction.c
index 20189f1cc7e..17a815cd446 100644
--- a/src/resolve/resolved-dns-transaction.c
+++ b/src/resolve/resolved-dns-transaction.c
@@ -633,7 +633,7 @@ static int on_stream_complete(DnsStream *s, int error) {
         if (ERRNO_IS_DISCONNECT(error) && s->protocol != DNS_PROTOCOL_LLMNR) {
                 log_debug_errno(error, "Connection failure for DNS TCP stream: %m");
 
-                if (s->transactions) {
+                if (error != ECONNRESET && s->transactions) {
                         DnsTransaction *t;
 
                         t = s->transactions;