feat(machine): add validation for machine names to accept only DNS labels

internal/machine/cluster/cluster.go

@@ -14,6 +14,7 @@ import (
 	"github.com/psviderski/uncloud/internal/machine/network"
 	"github.com/psviderski/uncloud/internal/machine/store"
 	"github.com/psviderski/uncloud/internal/secret"
+	"github.com/psviderski/uncloud/pkg/api"
 	"google.golang.org/grpc/codes"
 	"google.golang.org/grpc/status"
 	"google.golang.org/protobuf/types/known/emptypb"
@@ -87,6 +88,11 @@ func (c *Cluster) AddMachine(ctx context.Context, req *pb.AddMachineRequest) (*p
 func (c *Cluster) AddMachineWithoutReadyCheck(
 	ctx context.Context, req *pb.AddMachineRequest,
 ) (*pb.AddMachineResponse, error) {
+	if req.Name != "" {
+		if err := api.ValidateMachineName(req.Name); err != nil {
+			return nil, status.Error(codes.InvalidArgument, err.Error())
+		}
+	}
 	if req.Network == nil {
 		return nil, status.Error(codes.InvalidArgument, "network not set")
 	}

internal/machine/cluster/cluster_test.go

@@ -0,0 +1,28 @@
+package cluster
+
+import (
+	"context"
+	"testing"
+
+	"github.com/psviderski/uncloud/api/pb"
+	"github.com/stretchr/testify/require"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
+)
+
+func TestAddMachine_InvalidName(t *testing.T) {
+	t.Parallel()
+
+	ready := make(chan struct{})
+	close(ready)
+	// Invalid names must be rejected before any store access.
+	c := NewCluster(nil, nil, nil, ready)
+	for _, name := range []string{"VPS1", "worker.example", "rr", "nearest", "c337f00600de51ef4375c9a9a267dba5"} {
+		t.Run("add", func(t *testing.T) {
+			resp, err := c.AddMachine(context.Background(), &pb.AddMachineRequest{Name: name})
+			require.Nil(t, resp)
+			require.Equal(t, codes.InvalidArgument, status.Code(err))
+			require.ErrorContains(t, err, "invalid machine name")
+		})
+	}
+}

internal/machine/cluster/machine.go

@@ -6,6 +6,7 @@ import (
 	"strings"
 
 	"github.com/psviderski/uncloud/internal/secret"
+	"github.com/psviderski/uncloud/pkg/api"
 )
 
 // NewMachineID generates a new unique machine ID.
@@ -27,7 +28,7 @@ func NewRandomMachineName() (string, error) {
 // a numeric suffix ("-1", "-2", etc.) if needed.
 func DefaultMachineName(hostname string, existing []string) (string, error) {
 	name := machineNameFromHostname(hostname)
-	if name == "" {
+	if api.ValidateMachineName(name) != nil {
 		var err error
 		if name, err = NewRandomMachineName(); err != nil {
 			return "", err
@@ -38,7 +39,9 @@ func DefaultMachineName(hostname string, existing []string) (string, error) {
 		return name, nil
 	}
 	for i := 1; ; i++ {
-		candidate := fmt.Sprintf("%s-%d", name, i)
+		suffix := fmt.Sprintf("-%d", i)
+		base := strings.TrimRight(name[:min(len(name), 63-len(suffix))], "-")
+		candidate := base + suffix
 		if !slices.Contains(existing, candidate) {
 			return candidate, nil
 		}
@@ -55,12 +58,13 @@ func machineNameFromHostname(hostname string) string {
 	var b strings.Builder
 	for _, r := range label {
 		switch {
-		case r >= 'a' && r <= 'z', r >= '0' && r <= '9', r == '-', r == '_':
+		case r >= 'a' && r <= 'z', r >= '0' && r <= '9', r == '-':
 			b.WriteRune(r)
 		default:
 			b.WriteRune('-')
 		}
 	}
 	// Trim leading and trailing hyphens that may result from the sanitisation above.
-	return strings.Trim(b.String(), "-")
+	name := strings.Trim(b.String(), "-")
+	return strings.TrimRight(name[:min(len(name), 63)], "-")
 }

internal/machine/cluster/machine_test.go

@@ -1,8 +1,10 @@
 package cluster
 
 import (
+	"strings"
 	"testing"
 
+	"github.com/psviderski/uncloud/pkg/api"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
@@ -18,9 +20,11 @@ func TestMachineNameFromHostname(t *testing.T) {
 		{"simple", "web", "web"},
 		{"fqdn uses first label", "web-1.example.com", "web-1"},
 		{"uppercase lowercased", "Web-Server", "web-server"},
-		{"invalid chars replaced", "host_name@1", "host_name-1"},
-		{"trim surrounding hyphens", "-_host_-", "_host_"},
+		{"invalid chars replaced", "host_name@1", "host-name-1"},
+		{"trim surrounding hyphens", "-_host_-", "host"},
 		{"whitespace trimmed", "  myhost  ", "myhost"},
+		{"long hostname truncated", strings.Repeat("a", 64), strings.Repeat("a", 63)},
+		{"truncation trims trailing hyphen", strings.Repeat("a", 62) + "-b", strings.Repeat("a", 62)},
 		{"empty", "", ""},
 		{"only invalid chars", "@#", ""},
 		{"dot only", ".example.com", ""},
@@ -37,10 +41,12 @@ func TestDefaultMachineName(t *testing.T) {
 	t.Parallel()
 
 	t.Run("falls back to random", func(t *testing.T) {
-		// An empty or fully invalid hostname falls back to a random "machine-xxxx" name.
-		got, err := DefaultMachineName("***", nil)
-		require.NoError(t, err)
-		assert.Regexp(t, `^machine-[a-zA-Z0-9]{4}$`, got)
+		for _, hostname := range []string{"***", "rr", "nearest", strings.Repeat("a", 32)} {
+			got, err := DefaultMachineName(hostname, nil)
+			require.NoError(t, err)
+			assert.Regexp(t, `^machine-[a-z0-9]{4}$`, got)
+			require.NoError(t, api.ValidateMachineName(got))
+		}
 	})
 
 	tests := []struct {
@@ -49,10 +55,45 @@ func TestDefaultMachineName(t *testing.T) {
 		existing []string
 		want     string
 	}{
-		{"from hostname", "web-1.example.com", nil, "web-1"},
-		{"dedup against existing", "web", []string{"web"}, "web-1"},
-		{"dedup multiple", "web", []string{"web", "web-1"}, "web-2"},
-		{"sanitized", "My_Host", nil, "my_host"},
+		{
+			name:     "from hostname",
+			hostname: "web-1.example.com",
+			want:     "web-1",
+		},
+		{
+			name:     "dedup against existing",
+			hostname: "web",
+			existing: []string{"web"},
+			want:     "web-1",
+		},
+		{
+			name:     "dedup multiple",
+			hostname: "web",
+			existing: []string{"web", "web-1"},
+			want:     "web-2",
+		},
+		{
+			name:     "sanitized",
+			hostname: "My_Host",
+			want:     "my-host",
+		},
+		{
+			name:     "long hostname",
+			hostname: strings.Repeat("a", 64),
+			want:     strings.Repeat("a", 63),
+		},
+		{
+			name:     "dedup maximum length",
+			hostname: strings.Repeat("a", 63),
+			existing: []string{strings.Repeat("a", 63)},
+			want:     strings.Repeat("a", 61) + "-1",
+		},
+		{
+			name:     "dedup trims trailing hyphen",
+			hostname: strings.Repeat("a", 60) + "-bb",
+			existing: []string{strings.Repeat("a", 60) + "-bb"},
+			want:     strings.Repeat("a", 60) + "-1",
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
@@ -60,6 +101,7 @@ func TestDefaultMachineName(t *testing.T) {
 			got, err := DefaultMachineName(tt.hostname, tt.existing)
 			require.NoError(t, err)
 			assert.Equal(t, tt.want, got)
+			require.NoError(t, api.ValidateMachineName(got))
 		})
 	}
 }