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// Package testutil implements common testing utilities.
package testutil
import (
"fmt"
"net"
"net/http"
"testing"
"time"
"blitiri.com.ar/go/dnss/internal/trace"
"github.com/miekg/dns"
)
// WaitForDNSServer waits 5 seconds for a DNS server to start, and returns an
// error if it fails to do so.
// It does this by repeatedly querying the DNS server until it either replies
// or times out. Note we do not do any validation of the reply.
func WaitForDNSServer(addr string) error {
conn, err := dns.DialTimeout("udp", addr, 1*time.Second)
if err != nil {
return fmt.Errorf("dns.Dial error: %v", err)
}
defer conn.Close()
m := &dns.Msg{}
m.SetQuestion("unused.", dns.TypeA)
deadline := time.Now().Add(5 * time.Second)
tick := time.Tick(100 * time.Millisecond)
for (<-tick).Before(deadline) {
conn.SetDeadline(time.Now().Add(1 * time.Second))
conn.WriteMsg(m)
_, err := conn.ReadMsg()
if err == nil {
return nil
}
}
return fmt.Errorf("timed out")
}
// WaitForHTTPServer waits 5 seconds for an HTTP server to start, and returns
// an error if it fails to do so.
// It does this by repeatedly querying the server until it either replies or
// times out.
func WaitForHTTPServer(addr string) error {
c := http.Client{
Timeout: 100 * time.Millisecond,
}
deadline := time.Now().Add(5 * time.Second)
tick := time.Tick(100 * time.Millisecond)
for (<-tick).Before(deadline) {
_, err := c.Get("http://" + addr + "/testpoke")
if err == nil {
return nil
}
}
return fmt.Errorf("timed out")
}
// GetFreePort returns a free TCP port. This is hacky and not race-free, but
// it works well enough for testing purposes.
func GetFreePort() string {
l, _ := net.Listen("tcp", "localhost:0")
defer l.Close()
return l.Addr().String()
}
// DNSQuery is a convenient wrapper to issue simple DNS queries.
func DNSQuery(srv, addr string, qtype uint16) (*dns.Msg, dns.RR, error) {
m := new(dns.Msg)
m.SetQuestion(addr, qtype)
in, err := dns.Exchange(m, srv)
if err != nil {
return nil, nil, err
} else if len(in.Answer) > 0 {
return in, in.Answer[0], nil
} else {
return in, nil, nil
}
}
// TestResolver is a dnsserver.Resolver implementation for testing, so we can
// control its responses during tests.
type TestResolver struct {
// Has this resolver been initialized?
Initialized bool
// Maintain() sends a value over this channel.
MaintainC chan bool
// The last query we've seen.
LastQuery *dns.Msg
// What we will respond to queries.
Response *dns.Msg
RespError error
}
// NewTestResolver creates a new TestResolver with minimal initialization.
func NewTestResolver() *TestResolver {
return &TestResolver{
MaintainC: make(chan bool, 1),
}
}
// Init the resolver.
func (r *TestResolver) Init() error {
r.Initialized = true
return nil
}
// Maintain the resolver.
func (r *TestResolver) Maintain() {
r.MaintainC <- true
}
// Query handles the given query, returning the pre-recorded response.
func (r *TestResolver) Query(req *dns.Msg, tr *trace.Trace) (*dns.Msg, error) {
r.LastQuery = req
if r.Response != nil {
r.Response.Question = req.Question
r.Response.Authoritative = true
}
return r.Response, r.RespError
}
// ServeTestDNSServer starts the fake DNS server.
func ServeTestDNSServer(addr string, handler func(dns.ResponseWriter, *dns.Msg)) {
server := &dns.Server{
Addr: addr,
Handler: dns.HandlerFunc(handler),
Net: "udp",
}
err := server.ListenAndServe()
panic(err)
}
// MakeStaticHandler for the DNS server. The given answer must be a valid
// zone.
func MakeStaticHandler(tb testing.TB, answer string) func(dns.ResponseWriter, *dns.Msg) {
rr := NewRR(tb, answer)
return func(w dns.ResponseWriter, r *dns.Msg) {
m := &dns.Msg{}
m.SetReply(r)
m.Answer = append(m.Answer, rr)
w.WriteMsg(m)
}
}
func NewRR(tb testing.TB, s string) dns.RR {
rr, err := dns.NewRR(s)
if err != nil {
tb.Fatalf("Error parsing RR for testing: %v", err)
}
return rr
}
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