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net/dns/resolver: unexport Packet, only use it internally.

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Signed-off-by: David Anderson <danderson@tailscale.com>
This commit is contained in:
David Anderson
2021-03-31 23:06:47 -07:00
parent 5fb9e00ecf
commit f185d62dc8
4 changed files with 41 additions and 55 deletions
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43
net/dns/resolver/tsdns.go
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@@ -44,14 +44,9 @@ var (
errNotOurName = errors.New("not a Tailscale DNS name")
)
// Packet represents a DNS payload together with the address of its origin.
type Packet struct {
// Payload is the application layer DNS payload.
// Resolver assumes ownership of the request payload when it is enqueued
// and cedes ownership of the response payload when it is returned from NextResponse.
Payload []byte
// Addr is the source address for a request and the destination address for a response.
Addr netaddr.IPPort
type packet struct {
bs []byte
addr netaddr.IPPort // src for a request, dst for a response
}
// Resolver is a DNS resolver for nodes on the Tailscale network,
@@ -66,9 +61,9 @@ type Resolver struct {
forwarder *forwarder
// queue is a buffered channel holding DNS requests queued for resolution.
queue chan Packet
queue chan packet
// responses is an unbuffered channel to which responses are returned.
responses chan Packet
responses chan packet
// errors is an unbuffered channel to which errors are returned.
errors chan error
// closed signals all goroutines to stop.
@@ -88,8 +83,8 @@ func New(logf logger.Logf, linkMon *monitor.Mon) (*Resolver, error) {
r := &Resolver{
logf: logger.WithPrefix(logf, "dns: "),
linkMon: linkMon,
queue: make(chan Packet, queueSize),
responses: make(chan Packet),
queue: make(chan packet, queueSize),
responses: make(chan packet),
errors: make(chan error),
closed: make(chan struct{}),
}
@@ -153,11 +148,11 @@ func (r *Resolver) SetUpstreams(upstreams []net.Addr) {
// EnqueueRequest places the given DNS request in the resolver's queue.
// It takes ownership of the payload and does not block.
// If the queue is full, the request will be dropped and an error will be returned.
func (r *Resolver) EnqueueRequest(request Packet) error {
func (r *Resolver) EnqueueRequest(bs []byte, from netaddr.IPPort) error {
select {
case <-r.closed:
return ErrClosed
case r.queue <- request:
case r.queue <- packet{bs, from}:
return nil
default:
return errFullQueue
@@ -166,14 +161,14 @@ func (r *Resolver) EnqueueRequest(request Packet) error {
// NextResponse returns a DNS response to a previously enqueued request.
// It blocks until a response is available and gives up ownership of the response payload.
func (r *Resolver) NextResponse() (Packet, error) {
func (r *Resolver) NextResponse() (packet []byte, to netaddr.IPPort, err error) {
select {
case <-r.closed:
return Packet{}, ErrClosed
return nil, netaddr.IPPort{}, ErrClosed
case resp := <-r.responses:
return resp, nil
return resp.bs, resp.addr, nil
case err := <-r.errors:
return Packet{}, err
return nil, netaddr.IPPort{}, err
}
}
@@ -266,19 +261,19 @@ func (r *Resolver) ResolveReverse(ip netaddr.IP) (string, dns.RCode, error) {
func (r *Resolver) poll() {
defer r.wg.Done()
var packet Packet
var pkt packet
for {
select {
case <-r.closed:
return
case packet = <-r.queue:
case pkt = <-r.queue:
// continue
}
out, err := r.respond(packet.Payload)
out, err := r.respond(pkt.bs)
if err == errNotOurName {
err = r.forwarder.forward(packet)
err = r.forwarder.forward(pkt)
if err == nil {
// forward will send response into r.responses, nothing to do.
continue
@@ -293,11 +288,11 @@ func (r *Resolver) poll() {
// continue
}
} else {
packet.Payload = out
pkt.bs = out
select {
case <-r.closed:
return
case r.responses <- packet:
case r.responses <- pkt:
// continue
}
}