net/dns/resolver: unexport Resolve and ResolveReverse.

They're only used internally and in tests, and have surprising
semantics in that they only resolve MagicDNS names, not upstream
resolver queries.

Signed-off-by: David Anderson <danderson@tailscale.com>

net/dns/resolver/tsdns.go

@@ -171,10 +171,10 @@ func (r *Resolver) NextResponse() (packet []byte, to netaddr.IPPort, err error)
 	}
 }
 
-// Resolve maps a given domain name to the IP address of the host that owns it,
+// resolve maps a given domain name to the IP address of the host that owns it,
 // if the IP address conforms to the DNS resource type given by tp (one of A, AAAA, ALL).
 // The domain name must be in canonical form (with a trailing period).
-func (r *Resolver) Resolve(domain string, tp dns.Type) (netaddr.IP, dns.RCode, error) {
+func (r *Resolver) resolve(domain string, tp dns.Type) (netaddr.IP, dns.RCode, error) {
 	r.mu.Lock()
 	dnsMap := r.dnsMap
 	r.mu.Unlock()
@@ -240,9 +240,9 @@ func (r *Resolver) Resolve(domain string, tp dns.Type) (netaddr.IP, dns.RCode, e
 	}
 }
 
-// ResolveReverse returns the unique domain name that maps to the given address.
+// resolveReverse returns the unique domain name that maps to the given address.
 // The returned domain name is in canonical form (with a trailing period).
-func (r *Resolver) ResolveReverse(ip netaddr.IP) (string, dns.RCode, error) {
+func (r *Resolver) resolveReverse(ip netaddr.IP) (string, dns.RCode, error) {
 	r.mu.Lock()
 	dnsMap := r.dnsMap
 	r.mu.Unlock()
@@ -567,7 +567,7 @@ func (r *Resolver) respondReverse(query []byte, name string, resp *response) ([]
 	}
 
 	var err error
-	resp.Name, resp.Header.RCode, err = r.ResolveReverse(ip)
+	resp.Name, resp.Header.RCode, err = r.resolveReverse(ip)
 	if err != nil {
 		r.logf("resolving rdns: %v", ip, err)
 	}
@@ -607,7 +607,7 @@ func (r *Resolver) respond(query []byte) ([]byte, error) {
 		return r.respondReverse(query, name, resp)
 	}
 
-	resp.IP, resp.Header.RCode, err = r.Resolve(name, resp.Question.Type)
+	resp.IP, resp.Header.RCode, err = r.resolve(name, resp.Question.Type)
 	// This return code is special: it requests forwarding.
 	if resp.Header.RCode == dns.RCodeRefused {
 		return nil, errNotOurName

net/dns/resolver/tsdns_test.go

@@ -223,7 +223,7 @@ func TestResolve(t *testing.T) {
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			ip, code, err := r.Resolve(tt.qname, tt.qtype)
+			ip, code, err := r.resolve(tt.qname, tt.qtype)
 			if err != nil {
 				t.Errorf("err = %v; want nil", err)
 			}
@@ -260,7 +260,7 @@ func TestResolveReverse(t *testing.T) {
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			name, code, err := r.ResolveReverse(tt.ip)
+			name, code, err := r.resolveReverse(tt.ip)
 			if err != nil {
 				t.Errorf("err = %v; want nil", err)
 			}
@@ -476,7 +476,7 @@ func TestConcurrentSetMap(t *testing.T) {
 	}()
 	go func() {
 		defer wg.Done()
-		r.Resolve("test1.ipn.dev", dns.TypeA)
+		r.resolve("test1.ipn.dev", dns.TypeA)
 	}()
 	wg.Wait()
 }