more config

internal/config/config.go

@@ -23,6 +23,7 @@ import (
 	"strings"
 	"time"
 
+	"github.com/miekg/dns"
 	"gopkg.in/yaml.v3"
 )
 
@@ -202,7 +203,14 @@ type EDNS struct {
 	PreserveEDNS0 bool `yaml:"preserve"`
 }
 
+// ForwardZone routes the apex and every name below it exclusively to Servers.
+type ForwardZone struct {
+	Zone    string           `yaml:"zone" json:"zone"`
+	Servers []UpstreamServer `yaml:"servers" json:"servers"`
+}
+
 type Upstream struct {
+	ForwardZones []ForwardZone `yaml:"forward_zones,omitempty" json:"forward_zones,omitempty"`
 	// Servers is the upstream pool.
 	Servers []UpstreamServer `yaml:"servers"`
 	// Policy is "parallel" (query all, first answer wins), "random" (pick N)
@@ -962,6 +970,24 @@ func (c *Config) applyDefaults() {
 			l.MaxBytes = 512 << 20
 		}
 	}
+	for i := range c.Upstream.ForwardZones {
+		z := &c.Upstream.ForwardZones[i]
+		z.Zone = strings.ToLower(strings.TrimSuffix(strings.TrimSpace(z.Zone), "."))
+		for j := range z.Servers {
+			u := &z.Servers[j]
+			if u.Proto == "" {
+				u.Proto = "udp"
+			}
+			if u.Weight <= 0 {
+				u.Weight = 1
+			}
+			if u.Addr != "" {
+				if _, _, err := net.SplitHostPort(u.Addr); err != nil {
+					u.Addr = net.JoinHostPort(u.Addr, defaultPort(u.Proto))
+				}
+			}
+		}
+	}
 	for i := range c.Upstream.Servers {
 		u := &c.Upstream.Servers[i]
 		if u.Proto == "" {
@@ -1035,6 +1061,31 @@ func (c *Config) Validate() error {
 	if len(c.Upstream.Servers) == 0 {
 		add("upstream.servers must not be empty")
 	}
+	zones := map[string]bool{}
+	for i, z := range c.Upstream.ForwardZones {
+		name := strings.ToLower(strings.TrimSuffix(z.Zone, "."))
+		if _, ok := dns.IsDomainName(name); !ok || name == "" || strings.Contains(name, "*") {
+			add("upstream.forward_zones[%d]: invalid zone %q", i, z.Zone)
+		}
+		if zones[name] {
+			add("upstream.forward_zones[%d]: duplicate zone %q", i, z.Zone)
+		}
+		zones[name] = true
+		if len(z.Servers) == 0 {
+			add("upstream.forward_zones[%d]: servers must not be empty", i)
+		}
+		for _, u := range z.Servers {
+			host, port, err := net.SplitHostPort(u.Addr)
+			if err != nil || host == "" || port == "" {
+				add("upstream.forward_zones[%d]: invalid server address %q", i, u.Addr)
+			}
+			switch u.Proto {
+			case "udp", "tcp", "tls":
+			default:
+				add("upstream.forward_zones[%d]: invalid proto %q", i, u.Proto)
+			}
+		}
+	}
 	seen := map[string]bool{}
 	for i, u := range c.Upstream.Servers {
 		if u.Addr == "" {

internal/config/config_test.go

@@ -371,3 +371,33 @@ func writeTempConfig(t *testing.T, content string) string {
 	}
 	return path
 }
+
+func TestForwardZoneConfig(t *testing.T) {
+	c := Default()
+	c.Block.Enabled = false
+	c.Upstream.ForwardZones = []ForwardZone{{Zone: "LOCAL.", Servers: []UpstreamServer{{Addr: "10.10.0.1"}}}}
+	c.applyDefaults()
+	if err := c.Validate(); err != nil {
+		t.Fatal(err)
+	}
+	z := c.Upstream.ForwardZones[0]
+	if z.Zone != "local" || z.Servers[0].Addr != "10.10.0.1:53" || z.Servers[0].Proto != "udp" {
+		t.Fatalf("defaults: %+v", z)
+	}
+	for _, bad := range []ForwardZone{
+		{Zone: "*.local", Servers: z.Servers},
+		{Zone: "", Servers: z.Servers},
+		{Zone: "local"},
+		{Zone: "local", Servers: []UpstreamServer{{Addr: "", Proto: "udp"}}},
+		{Zone: "local", Servers: []UpstreamServer{{Addr: "10.10.0.1:53", Proto: "http"}}},
+	} {
+		c.Upstream.ForwardZones = []ForwardZone{bad}
+		if err := c.Validate(); err == nil {
+			t.Fatalf("accepted %+v", bad)
+		}
+	}
+	c.Upstream.ForwardZones = []ForwardZone{z, z}
+	if err := c.Validate(); err == nil {
+		t.Fatal("accepted duplicate zone")
+	}
+}