[#6] Implement version constraints / downgrade protection

Signed-off-by: Knut Ahlers <knut@ahlers.me>

docs/config.md

@@ -18,6 +18,11 @@ catalog:
         name: 'Website'
         url: 'https://alpinelinux.org'
 
+    version_constraint:
+      allow_downgrade: false
+      allow_prerelease: false
+      type: semver
+
 check_interval: 1h
 
 ...
@@ -29,6 +34,8 @@ Additionally you will configure a `fetcher` with its corresponding `fetcher_conf
 
 You can provide your own `links` for each catalog entry which will be added to or override the links returned from the fetcher. If you provide the same `name` as the fetcher uses the link of the fetcher will be overridden. The `icon_class` should consist of `fas` or `fab` and an icon (for example `fa-globe`). You can use all **solid** (`fas`) or **breand** (`fab`) icons within [Font Awesome v5 Free](https://fontawesome.com/v5.15/icons?d=gallery&s=brands,solid&m=free).
 
+For the `version_constraint`s you must specify a `type` to parse the version returned by the fetcher (currently `semver` and `numeric_dot` (`104.0.5112.79`) are supported) and then can allow downgrades and pre-releases in the version. If no constraint is present, versions are neither parsed nor checked for downgrade / pre-release. If only the `type` is specified, downgrades and pre-releases are forbidden.
+
 ## Available Fetchers
 
 ## Fetcher: `atlassian`

docs/config.md.tpl

@@ -18,6 +18,11 @@ catalog:
         name: 'Website'
         url: 'https://alpinelinux.org'
 
+    version_constraint:
+      allow_downgrade: false
+      allow_prerelease: false
+      type: semver
+
 check_interval: 1h
 
 ...
@@ -29,6 +34,8 @@ Additionally you will configure a `fetcher` with its corresponding `fetcher_conf
 
 You can provide your own `links` for each catalog entry which will be added to or override the links returned from the fetcher. If you provide the same `name` as the fetcher uses the link of the fetcher will be overridden. The `icon_class` should consist of `fas` or `fab` and an icon (for example `fa-globe`). You can use all **solid** (`fas`) or **breand** (`fab`) icons within [Font Awesome v5 Free](https://fontawesome.com/v5.15/icons?d=gallery&s=brands,solid&m=free).
 
+For the `version_constraint`s you must specify a `type` to parse the version returned by the fetcher (currently `semver` and `numeric_dot` (`104.0.5112.79`) are supported) and then can allow downgrades and pre-releases in the version. If no constraint is present, versions are neither parsed nor checked for downgrade / pre-release. If only the `type` is specified, downgrades and pre-releases are forbidden.
+
 ## Available Fetchers
 
 {% for module in modules -%}

internal/database/store.go

@@ -8,6 +8,7 @@ import (
 	"gorm.io/gorm"
 	"gorm.io/gorm/clause"
 
+	"github.com/Luzifer/go-latestver/internal/version"
 	"github.com/Luzifer/go_helpers/v2/fieldcollection"
 )
 
@@ -19,6 +20,8 @@ type (
 		Fetcher       string                           `json:"-" yaml:"fetcher"`
 		FetcherConfig *fieldcollection.FieldCollection `json:"-" yaml:"fetcher_config"`
 
+		VersionConstraint *version.Constraint `json:"-" yaml:"version_constraint"`
+
 		Links []CatalogLink `json:"links" yaml:"links"`
 	}
 

internal/version/constraint.go

@@ -0,0 +1,68 @@
+package version
+
+import "github.com/pkg/errors"
+
+type (
+	Constraint struct {
+		AllowDowngrade  bool `yaml:"allow_downgrade"`
+		AllowPrerelease bool `yaml:"allow_prerelease"`
+
+		Type string `yaml:"type"`
+	}
+
+	comparer interface {
+		Compare(oldVersion, newVersion string) (compareResult, error)
+		IsPrerelease(newVersion string) (bool, error)
+	}
+
+	compareResult uint
+)
+
+const (
+	compareResultInvalid compareResult = iota
+	compareResultEqual
+	compareResultDowngrade
+	compareResultUpgrade
+)
+
+func (c Constraint) ShouldApply(oldVersion, newVersion string) (bool, error) {
+	comp := c.getComparer()
+	if comp == nil {
+		return false, errors.New("invalid version type specified")
+	}
+
+	// Compare versions and check for UpgradeOnly flag
+	compResult, err := comp.Compare(oldVersion, newVersion)
+	if err != nil {
+		return false, errors.Wrap(err, "comparing versions")
+	}
+
+	if !c.AllowDowngrade && compResult != compareResultUpgrade {
+		return false, nil
+	}
+
+	// check for forbidden pre-releases
+	isPreR, err := comp.IsPrerelease(newVersion)
+	if err != nil {
+		return false, errors.Wrap(err, "checking pre-release")
+	}
+
+	if !c.AllowPrerelease && isPreR {
+		return false, nil
+	}
+
+	return true, nil
+}
+
+func (c Constraint) getComparer() comparer {
+	switch c.Type {
+	case "numeric_dot":
+		return numericDotSeparatedComparer{}
+
+	case "semver":
+		return semVerComparer{}
+
+	default:
+		return nil
+	}
+}

internal/version/numeric_dot.go

@@ -0,0 +1,68 @@
+package version
+
+import (
+	"math"
+	"strconv"
+	"strings"
+
+	"github.com/pkg/errors"
+)
+
+type (
+	numericDotSeparatedComparer struct{}
+)
+
+var _ comparer = numericDotSeparatedComparer{}
+
+func (n numericDotSeparatedComparer) Compare(oldVersion, newVersion string) (compareResult, error) {
+	oldV, err := n.parse(oldVersion)
+	if err != nil {
+		return compareResultInvalid, errors.Wrap(err, "parsing old version")
+	}
+
+	newV, err := n.parse(newVersion)
+	if err != nil {
+		return compareResultInvalid, errors.Wrap(err, "parsing old version")
+	}
+
+	getSeg := func(v []int, i int) int {
+		if i >= len(v) {
+			return 0
+		}
+		return v[i]
+	}
+
+	for i := 0; i < int(math.Max(float64(len(oldV)), float64(len(newV)))); i++ {
+		switch {
+		case getSeg(oldV, i) < getSeg(newV, i):
+			return compareResultUpgrade, nil
+
+		case getSeg(oldV, i) > getSeg(newV, i):
+			return compareResultDowngrade, nil
+
+		default:
+			continue
+		}
+	}
+
+	return compareResultEqual, nil
+}
+
+func (numericDotSeparatedComparer) IsPrerelease(string) (bool, error) {
+	// Numeric Dot has no marker for Pre-Releases
+	return false, nil
+}
+
+func (numericDotSeparatedComparer) parse(ver string) ([]int, error) {
+	var out []int
+
+	for _, seg := range strings.Split(ver, ".") {
+		segI, err := strconv.Atoi(seg)
+		if err != nil {
+			return nil, errors.Wrap(err, "parsing segment")
+		}
+		out = append(out, segI)
+	}
+
+	return out, nil
+}

internal/version/numeric_dot_test.go

@@ -0,0 +1,27 @@
+package version
+
+import "testing"
+
+func TestNumericDotSeparatedCompareFunc(t *testing.T) {
+	comp := numericDotSeparatedComparer{}
+
+	for _, tc := range []struct {
+		v1, v2 string
+		res    compareResult
+	}{
+		{"2.1.0", "2.1.1", compareResultUpgrade},
+		{"2.1.1", "2.1.0", compareResultDowngrade},
+		{"2.1.1", "2.1.1", compareResultEqual},
+		{"103.0.5060.134", "104.0.5112.79", compareResultUpgrade},
+		{"2022.7.7", "2022.8.0", compareResultUpgrade},
+	} {
+		res, err := comp.Compare(tc.v1, tc.v2)
+		if err != nil {
+			t.Errorf("Comparing %q to %q: %s", tc.v1, tc.v2, err)
+		}
+
+		if res != tc.res {
+			t.Errorf("Comparing %q to %q: expected %v, got %v", tc.v1, tc.v2, tc.res, res)
+		}
+	}
+}

internal/version/semver.go

@@ -0,0 +1,51 @@
+package version
+
+import (
+	"github.com/blang/semver/v4"
+	"github.com/pkg/errors"
+)
+
+type (
+	semVerComparer struct{}
+)
+
+var _ comparer = semVerComparer{}
+
+func (semVerComparer) Compare(oldVersion, newVersion string) (compareResult, error) {
+	oldS, err := semver.Make(oldVersion)
+	if err != nil {
+		return compareResultInvalid, errors.Wrap(err, "parsing old version")
+	}
+
+	newS, err := semver.Make(newVersion)
+	if err != nil {
+		return compareResultInvalid, errors.Wrap(err, "parsing new version")
+	}
+
+	switch oldS.Compare(newS) {
+	case -1:
+		// oldS < newS
+		return compareResultUpgrade, nil
+
+	case 0:
+		// oldS == newS
+		return compareResultEqual, nil
+
+	case 1:
+		// oldS > newS
+		return compareResultDowngrade, nil
+
+	default:
+		// WTF, that does not exist according to lib docs
+		return compareResultInvalid, errors.New("invalid compare result")
+	}
+}
+
+func (semVerComparer) IsPrerelease(newVersion string) (bool, error) {
+	newS, err := semver.Make(newVersion)
+	if err != nil {
+		return false, errors.Wrap(err, "parsing version")
+	}
+
+	return newS.Pre != nil, nil
+}

internal/version/semver_test.go

@@ -0,0 +1,27 @@
+package version
+
+import "testing"
+
+func TestSemVerCompareFunc(t *testing.T) {
+	comp := semVerComparer{}
+
+	for _, tc := range []struct {
+		v1, v2 string
+		res    compareResult
+	}{
+		{"1.0.0", "2.0.0", compareResultUpgrade},
+		{"2.0.0", "2.1.0", compareResultUpgrade},
+		{"2.1.0", "2.1.1", compareResultUpgrade},
+		{"2.1.1", "2.1.0", compareResultDowngrade},
+		{"2.1.1", "2.1.1", compareResultEqual},
+	} {
+		res, err := comp.Compare(tc.v1, tc.v2)
+		if err != nil {
+			t.Errorf("Comparing %q to %q: %s", tc.v1, tc.v2, err)
+		}
+
+		if res != tc.res {
+			t.Errorf("Comparing %q to %q: expected %v, got %v", tc.v1, tc.v2, tc.res, res)
+		}
+	}
+}

scheduler.go

@@ -59,18 +59,35 @@ func checkForUpdates(ce *database.CatalogEntry) error {
 	ver = strings.TrimPrefix(ver, "v")
 	vertime = vertime.Truncate(time.Second).UTC()
 
+	logger = logger.WithFields(log.Fields{
+		"from": cm.CurrentVersion,
+		"to":   ver,
+	})
+
+	var (
+		compareErr   error
+		shouldUpdate = true
+	)
+	if ce.VersionConstraint != nil {
+		shouldUpdate, compareErr = ce.VersionConstraint.ShouldApply(cm.CurrentVersion, ver)
+	}
+
 	switch {
 
 	case err != nil:
-		log.WithField("entry", ce.Key()).WithError(err).Error("Fetcher caused error, error is stored in entry")
+		logger.WithError(err).Error("Fetcher caused error, error is stored in entry")
 		cm.Error = err.Error()
 
-	case cm.CurrentVersion != ver:
+	case compareErr != nil:
+		logger.WithError(err).Error("Version compare caused error, error is stored in entry")
+		cm.Error = compareErr.Error()
 
-		logger.WithFields(log.Fields{
-			"from": cm.CurrentVersion,
-			"to":   ver,
-		}).Info("Entry had version update")
+	case cm.CurrentVersion != ver && !shouldUpdate:
+		logger.Info("Version-updated prevented by constraints")
+		cm.Error = ""
+
+	case cm.CurrentVersion != ver && shouldUpdate:
+		logger.Info("Entry had version update")
 
 		if err = storage.Logs.Add(&database.LogEntry{
 			CatalogName: ce.Name,
@@ -84,7 +101,11 @@ func checkForUpdates(ce *database.CatalogEntry) error {
 
 		cm.VersionTime = ptrTime(vertime)
 		cm.CurrentVersion = ver
-		fallthrough
+		cm.Error = ""
+
+	case cm.CurrentVersion == ver:
+		logger.Debug("Version did not change")
+		cm.Error = ""
 
 	default:
 		cm.Error = ""