TheArchive/tailscale
1
0
Fork 0
mirror of https://github.com/tailscale/tailscale.git synced 2025-08-22 11:01:54 +00:00
Code Issues Packages Projects Releases Wiki Activity

net/dns: retry forwarder requests over TCP

Browse Source 
We weren't correctly retrying truncated requests to an upstream DNS
server with TCP. Instead, we'd return a truncated request to the user,
even if the user was querying us over TCP and thus able to handle a
large response.

Also, add an envknob and controlknob to allow users/us to disable this
behaviour if it turns out to be buggy (✨ DNS ✨).

Updates #9264

Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: Ifb04b563839a9614c0ba03e9c564e8924c1a2bfd
This commit is contained in:
Andrew Dunham
2023-09-07 16:27:50 -04:00
parent 098d110746
commit 530aaa52f1
13 changed files with 448 additions and 49 deletions
Download Patch File Download Diff File Expand all files Collapse all files

16
net/dns/manager.go
View File

@@ -17,6 +17,7 @@ import (
"sync/atomic"
"time"
"tailscale.com/control/controlknobs"
"tailscale.com/health"
"tailscale.com/net/dns/resolver"
"tailscale.com/net/netmon"
@@ -66,14 +67,14 @@ type Manager struct {
// NewManagers created a new manager from the given config.
// The netMon parameter is optional; if non-nil it's used to do faster interface lookups.
func NewManager(logf logger.Logf, oscfg OSConfigurator, netMon *netmon.Monitor, dialer *tsdial.Dialer, linkSel resolver.ForwardLinkSelector) *Manager {
func NewManager(logf logger.Logf, oscfg OSConfigurator, netMon *netmon.Monitor, dialer *tsdial.Dialer, linkSel resolver.ForwardLinkSelector, knobs *controlknobs.Knobs) *Manager {
if dialer == nil {
panic("nil Dialer")
}
logf = logger.WithPrefix(logf, "dns: ")
m := &Manager{
logf: logf,
resolver: resolver.New(logf, netMon, linkSel, dialer),
resolver: resolver.New(logf, netMon, linkSel, dialer, knobs),
os: oscfg,
}
m.ctx, m.ctxCancel = context.WithCancel(context.Background())
@@ -295,7 +296,10 @@ func toIPsOnly(resolvers []*dnstype.Resolver) (ret []netip.Addr) {
// Query executes a DNS query received from the given address. The query is
// provided in bs as a wire-encoded DNS query without any transport header.
// This method is called for requests arriving over UDP and TCP.
func (m *Manager) Query(ctx context.Context, bs []byte, from netip.AddrPort) ([]byte, error) {
//
// The "family" parameter should indicate what type of DNS query this is:
// either "tcp" or "udp".
func (m *Manager) Query(ctx context.Context, bs []byte, family string, from netip.AddrPort) ([]byte, error) {
select {
case <-m.ctx.Done():
return nil, net.ErrClosed
@@ -309,7 +313,7 @@ func (m *Manager) Query(ctx context.Context, bs []byte, from netip.AddrPort) ([]
return nil, errFullQueue
}
defer atomic.AddInt32(&m.activeQueriesAtomic, -1)
return m.resolver.Query(ctx, bs, from)
return m.resolver.Query(ctx, bs, family, from)
}
const (
@@ -371,7 +375,7 @@ func (s *dnsTCPSession) handleWrites() {
}
func (s *dnsTCPSession) handleQuery(q []byte) {
resp, err := s.m.Query(s.ctx, q, s.srcAddr)
resp, err := s.m.Query(s.ctx, q, "tcp", s.srcAddr)
if err != nil {
s.m.logf("tcp query: %v", err)
return
@@ -466,7 +470,7 @@ func Cleanup(logf logger.Logf, interfaceName string) {
logf("creating dns cleanup: %v", err)
return
}
dns := NewManager(logf, oscfg, nil, &tsdial.Dialer{Logf: logf}, nil)
dns := NewManager(logf, oscfg, nil, &tsdial.Dialer{Logf: logf}, nil, nil)
if err := dns.Down(); err != nil {
logf("dns down: %v", err)
}