feature/conn25: keep addrAssignments through pool reconfig

Fixes tailscale/corp#40250 Signed-off-by: Fran Bull <fran@tailscale.com>
2026-05-11 14:58:08 -07:00
parent e4e59a2af0
commit 3a6261b79b
4 changed files with 193 additions and 38 deletions
@@ -5,6 +5,7 @@ package conn25

 import (
 	"encoding/json"
+	"errors"
 	"net/http"
 	"net/http/httptest"
 	"net/netip"
@@ -2368,3 +2369,69 @@ func TestGetMagicRange(t *testing.T) {
 		}
 	}
 }
+
+func TestReconfigDoesNotReissueInUseAddresses(t *testing.T) {
+	appName := "app1"
+	mustRange := func(from, to string) netipx.IPRange {
+		return netipx.IPRangeFrom(netip.MustParseAddr(from), netip.MustParseAddr(to))
+	}
+	beforeRangeV4 := mustRange("0.0.0.1", "0.0.0.3")
+	beforeRangeV6 := mustRange("::1", "::3")
+	afterRangeV4 := mustRange("0.0.0.4", "0.0.0.7")
+	afterRangeV6 := mustRange("::4", "::7")
+	makeNodeFromMagicRange := func(v4, v6 netipx.IPRange) tailcfg.NodeView {
+		return makeSelfNode(t, []appctype.Conn25Attr{{
+			Name:            appName,
+			Connectors:      []string{"tag:woo"},
+			Domains:         []string{"example.com"},
+			V4MagicIPPool:   []netipx.IPRange{v4},
+			V6MagicIPPool:   []netipx.IPRange{v6},
+			V4TransitIPPool: []netipx.IPRange{mustRange("169.254.0.0", "169.254.0.10")},
+			V6TransitIPPool: []netipx.IPRange{mustRange("fd7a:115c:a1e0:a99c:0200::", "fd7a:115c:a1e0:a99c:0200::10")},
+		}}, []string{})
+	}
+	domain := must.Get(dnsname.ToFQDN("example.com."))
+
+	for _, tt := range []struct {
+		name   string
+		dstOne netip.Addr
+		dstTwo netip.Addr
+	}{
+		{
+			name:   "v4",
+			dstOne: netip.MustParseAddr("0.0.0.100"),
+			dstTwo: netip.MustParseAddr("0.0.0.101"),
+		},
+		{
+			name:   "v6",
+			dstOne: netip.MustParseAddr("::100"),
+			dstTwo: netip.MustParseAddr("::101"),
+		},
+	} {
+		t.Run(tt.name, func(t *testing.T) {
+			c := newConn25(t.Logf)
+			ext := &extension{
+				conn25: c,
+			}
+
+			_, err := c.client.reserveAddresses(appName, domain, tt.dstOne)
+			if !errors.Is(err, errUninitializedIPPool) {
+				t.Fatalf("want %v, got %v", errUninitializedIPPool, err)
+			}
+
+			ext.onSelfChange(makeNodeFromMagicRange(beforeRangeV4, beforeRangeV6))
+			beforeAddrs, err := c.client.reserveAddresses(appName, domain, tt.dstOne)
+			if err != nil {
+				t.Fatal(err)
+			}
+			ext.onSelfChange(makeNodeFromMagicRange(afterRangeV4, afterRangeV6))
+			afterAddrs, err := c.client.reserveAddresses(appName, domain, tt.dstTwo)
+			if err != nil {
+				t.Fatal(err)
+			}
+			if afterAddrs.magic == beforeAddrs.magic {
+				t.Errorf("pool reissued magic: %v that was already assigned", beforeAddrs.magic)
+			}
+		})
+	}
+}