link: validate local links using validator framework/allow local reanchor.

pkg/mdformatter/linktransformer/config.go

@@ -22,6 +22,9 @@ type Config struct {
 
 	Cache cache.Config `yaml:"cache"`
 
+	// ExplicitLocalValidators forces all links (remote and local) to go through validators.
+	// If false (default), only http(s) links go to validators.
+	// Use it for additional the validation options on local links.
 	ExplicitLocalValidators bool              `yaml:"explicitLocalValidators"`
 	Validators              []ValidatorConfig `yaml:"validators"`
 	Timeout                 string            `yaml:"timeout"`
@@ -38,14 +41,17 @@ type Config struct {
 type ValidatorConfig struct {
 	// Regex for type of validator. For `githubPullsIssues` this is: (^http[s]?:\/\/)(www\.)?(github\.com\/){ORG_NAME}\/{REPO_NAME}(\/pull\/|\/issues\/).
 	Regex string `yaml:"regex"`
-	// By default type is `roundtrip`. Could be `githubPullsIssues` or `ignore`.
+	// By default type is `roundtrip`. Could be `githubPullsIssues`, `ignore`, or `local`.
 	Type ValidatorType `yaml:"type"`
 	// GitHub repo token to avoid getting rate limited.
 	Token string `yaml:"token"`
+	// Anchor for additional path to add before the local link check.
+	Anchor string `yaml:"anchor"`
 
 	ghValidator GitHubPullsIssuesValidator
 	rtValidator RoundTripValidator
 	igValidator IgnoreValidator
+	lValidator  LocalValidator
 }
 
 type RoundTripValidator struct {
@@ -61,12 +67,17 @@ type IgnoreValidator struct {
 	_regex *regexp.Regexp
 }
 
+type LocalValidator struct {
+	_regex *regexp.Regexp
+	anchor string
+}
 type ValidatorType string
 
 const (
 	roundtripValidator         ValidatorType = "roundtrip"
 	githubPullsIssuesValidator ValidatorType = "githubPullsIssues"
 	ignoreValidator            ValidatorType = "ignore"
+	localValidator             ValidatorType = "local"
 )
 
 const (
@@ -124,8 +135,12 @@ func ParseConfig(c []byte) (Config, error) {
 			cfg.Validators[i].ghValidator._maxNum = maxNum
 		case ignoreValidator:
 			cfg.Validators[i].igValidator._regex = regexp.MustCompile(cfg.Validators[i].Regex)
+		case localValidator:
+			cfg.Validators[i].lValidator._regex = regexp.MustCompile(cfg.Validators[i].Regex)
+			cfg.Validators[i].lValidator.anchor = cfg.Validators[i].Anchor
+
 		default:
-			return Config{}, errors.New("Validator type not supported")
+			return Config{}, fmt.Errorf("validator type %v not supported", cfg.Validators[i].Type)
 		}
 	}
 	return cfg, nil

pkg/mdformatter/linktransformer/link.go

@@ -398,28 +398,6 @@ func (v *validator) Close(ctx mdformatter.SourceContext) error {
 	return merr.Err()
 }
 
-func (v *validator) checkLocal(k futureKey) bool {
-	v.l.localLinksChecked.Inc()
-	// Check if link is email address.
-	if email := strings.TrimPrefix(k.dest, "mailto:"); email != k.dest {
-		if isValidEmail(email) {
-			return true
-		}
-		v.destFutures[k].resultFn = func() error { return fmt.Errorf("provided mailto link is not a valid email, got %v", k.dest) }
-		return false
-	}
-
-	// Relative or absolute path. Check if exists.
-	newDest := absLocalLink(v.anchorDir, k.filepath, k.dest)
-
-	// Local link. Check if exists.
-	if err := v.localLinks.Lookup(newDest); err != nil {
-		v.destFutures[k].resultFn = func() error { return fmt.Errorf("link %v, normalized to: %w", k.dest, err) }
-		return false
-	}
-	return true
-}
-
 func (v *validator) visit(filepath string, dest string, lineNumbers string) {
 	v.futureMu.Lock()
 	defer v.futureMu.Unlock()
@@ -432,39 +410,19 @@ func (v *validator) visit(filepath string, dest string, lineNumbers string) {
 	if !v.validateConfig.ExplicitLocalValidators {
 		matches := remoteLinkPrefixRe.FindAllStringIndex(dest, 1)
 		if matches == nil {
-			v.checkLocal(k)
+			_, _ = LocalValidator{}.IsValid(k, v)
 			return
 		}
 		v.l.remoteLinksChecked.Inc()
 	}
 
+	// TODO: Capture error?
 	validator := v.validateConfig.GetValidatorForURL(dest)
 	if validator != nil {
-		matched, err := validator.IsValid(k, v)
-		if matched && err == nil {
-			return
-		}
+		_, _ = validator.IsValid(k, v)
+		return
 	}
-}
 
-// isValidEmail checks email structure and domain.
-func isValidEmail(email string) bool {
-	// Check length.
-	if len(email) < 3 && len(email) > 254 {
-		return false
-	}
-	// Regex from https://www.w3.org/TR/2016/REC-html51-20161101/sec-forms.html#email-state-typeemail.
-	var emailRe = regexp.MustCompile("^[a-zA-Z0-9.!#$%&'*+\\/=?^_`{|}~-]+@[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:\\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*$")
-	if !emailRe.MatchString(email) {
-		return false
-	}
-	// Check email domain.
-	domain := strings.Split(email, "@")
-	mx, err := net.LookupMX(domain[1])
-	if err != nil || len(mx) == 0 {
-		return false
-	}
-	return true
 }
 
 type localLinksCache map[string]*[]string

pkg/mdformatter/linktransformer/validator.go

@@ -5,6 +5,9 @@ package linktransformer
 
 import (
 	"fmt"
+	"net"
+	"path/filepath"
+	"regexp"
 	"strconv"
 	"strings"
 )
@@ -13,6 +16,52 @@ type Validator interface {
 	IsValid(k futureKey, r *validator) (bool, error)
 }
 
+func (v LocalValidator) IsValid(k futureKey, r *validator) (bool, error) {
+	r.l.localLinksChecked.Inc()
+	// Check if link is email address.
+	if email := strings.TrimPrefix(k.dest, "mailto:"); email != k.dest {
+		if isValidEmail(email) {
+			return true, nil
+		}
+		r.destFutures[k].resultFn = func() error { return fmt.Errorf("provided mailto link is not a valid email, got %v", k.dest) }
+		return false, nil
+	}
+
+	anchorDir := r.anchorDir
+	if v.anchor != "" {
+		anchorDir = filepath.Join(anchorDir, v.anchor)
+	}
+	// Relative or absolute path. Check if exists.
+	newDest := absLocalLink(anchorDir, k.filepath, k.dest)
+
+	// Local link. Check if exists.
+	if err := r.localLinks.Lookup(newDest); err != nil {
+		r.destFutures[k].resultFn = func() error { return fmt.Errorf("link %v, normalized to: %w", k.dest, err) }
+		return false, nil
+	}
+	return true, nil
+}
+
+// isValidEmail checks email structure and domain.
+func isValidEmail(email string) bool {
+	// Check length.
+	if len(email) < 3 && len(email) > 254 {
+		return false
+	}
+	// Regex from https://www.w3.org/TR/2016/REC-html51-20161101/sec-forms.html#email-state-typeemail.
+	var emailRe = regexp.MustCompile("^[a-zA-Z0-9.!#$%&'*+\\/=?^_`{|}~-]+@[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:\\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*$")
+	if !emailRe.MatchString(email) {
+		return false
+	}
+	// Check email domain.
+	domain := strings.Split(email, "@")
+	mx, err := net.LookupMX(domain[1])
+	if err != nil || len(mx) == 0 {
+		return false
+	}
+	return true
+}
+
 // GitHubPullsIssuesValidator.IsValid skips visiting all GitHub issue/PR links.
 func (v GitHubPullsIssuesValidator) IsValid(k futureKey, r *validator) (bool, error) {
 	r.l.githubSkippedLinks.Inc()
@@ -36,7 +85,7 @@ func (v RoundTripValidator) IsValid(k futureKey, r *validator) (bool, error) {
 	matches := remoteLinkPrefixRe.FindAllStringIndex(k.dest, 1)
 	if matches == nil && r.validateConfig.ExplicitLocalValidators {
 		r.l.localLinksChecked.Inc()
-		return r.checkLocal(k), nil
+		return LocalValidator{}.IsValid(k, r)
 	}
 
 	// Result will be in future.
@@ -72,7 +121,7 @@ func (v RoundTripValidator) IsValid(k futureKey, r *validator) (bool, error) {
 	return true, nil
 }
 
-// IgnoreValidator.IsValid returns true if matched so that link in not checked.
+// IsValid returns true if matched so that link in not checked.
 func (v IgnoreValidator) IsValid(k futureKey, r *validator) (bool, error) {
 	r.l.ignoreSkippedLinks.Inc()
 
@@ -98,6 +147,11 @@ func (v Config) GetValidatorForURL(URL string) Validator {
 				continue
 			}
 			return val.igValidator
+		case localValidator:
+			if !val.lValidator._regex.MatchString(URL) {
+				continue
+			}
+			return val.lValidator
 		default:
 			panic("unexpected validator type")
 		}