TheArchive/tailscale
1
0
Fork 0
mirror of https://github.com/tailscale/tailscale.git synced 2025-12-05 04:11:59 +00:00
Code Issues Packages Projects Releases Wiki Activity

net/dns/resolver: update (*forwarder).forwardWithDestChan to always return an error unless it sends a response to responseChan

Browse Source 
We currently have two executions paths where (*forwarder).forwardWithDestChan
returns nil, rather than an error, without sending a DNS response to responseChan.

These paths are accompanied by a comment that reads:
// Returning an error will cause an internal retry, there is
// nothing we can do if parsing failed. Just drop the packet.
But it is not (or no longer longer) accurate: returning an error from forwardWithDestChan
does not currently cause a retry.

Moreover, although these paths are currently unreachable due to implementation details,
if (*forwarder).forwardWithDestChan were to return nil without sending a response to
responseChan, it would cause a deadlock at one call site and a panic at another.

Therefore, we update (*forwarder).forwardWithDestChan to return errors in those two paths
and remove comments that were no longer accurate and misleading.

Updates #cleanup
Updates #13571

Signed-off-by: Nick Hill <mykola.khyl@gmail.com>
This commit is contained in:
Nick Hill
2024-10-04 15:11:46 -05:00
committed by Nick Khyl
parent e7545f2eac
commit c2144c44a3
3 changed files with 15 additions and 16 deletions
Download Patch File Download Diff File Expand all files Collapse all files

10
net/dns/resolver/forwarder.go
View File

@@ -920,10 +920,7 @@ func (f *forwarder) forwardWithDestChan(ctx context.Context, query packet, respo
metricDNSFwdDropBonjour.Add(1)
res, err := nxDomainResponse(query)
if err != nil {
f.logf("error parsing bonjour query: %v", err)
// Returning an error will cause an internal retry, there is
// nothing we can do if parsing failed. Just drop the packet.
return nil
return err
}
select {
case <-ctx.Done():
@@ -955,10 +952,7 @@ func (f *forwarder) forwardWithDestChan(ctx context.Context, query packet, respo
res, err := servfailResponse(query)
if err != nil {
f.logf("building servfail response: %v", err)
// Returning an error will cause an internal retry, there is
// nothing we can do if parsing failed. Just drop the packet.
return nil
return err
}
select {
case <-ctx.Done():