htpasswd: clean up errors

Signed-off-by: Alejandro Mery <amery@jpi.io>

htpasswd/errors.go

@@ -0,0 +1,49 @@
+package htpasswd
+
+import (
+	"errors"
+	"strings"
+)
+
+var (
+	// ErrExists indicates the specified user already exists
+	ErrExists = errors.New("user already exists")
+	// ErrNotExists indicates the specified user does not exist
+	ErrNotExists = errors.New("user does not exist")
+	// ErrInvalidAlgorithm indicates the htpasswd entry doesn't contain a
+	// valid algorithm signature
+	ErrInvalidAlgorithm = errors.New("invalid algorithm")
+	// ErrInvalidPassword indicates the offered password doesn't match
+	ErrInvalidPassword = errors.New("invalid password")
+)
+
+// UserError indicates an error associated to the specified user
+type UserError struct {
+	Name string
+	Hint string
+	Err  error
+}
+
+func (e *UserError) Error() string {
+	var buf strings.Builder
+	var reason string
+
+	if e.Hint != "" {
+		reason = e.Hint
+	} else {
+		reason = e.Err.Error()
+	}
+
+	if e.Name == "" {
+		return reason
+	}
+
+	_, _ = buf.WriteString(e.Name)
+	_, _ = buf.WriteString(": ")
+	_, _ = buf.WriteString(reason)
+	return buf.String()
+}
+
+func (e *UserError) Unwrap() error {
+	return e.Err
+}

htpasswd/htpasswd.go

@@ -51,8 +51,10 @@ func Parse(htpasswdBytes []byte) (Passwds, error) {
 		_, exists := passwords[parts[0]]
 
 		if exists {
-			err = errors.New("invalid htpasswd file - user " +
-				parts[0] + " defined more than once")
+			err = &UserError{
+				Name: parts[0],
+				Err:  ErrExists,
+			}
 			return passwords, err
 		}
 		passwords[parts[0]] = parts[1]
@@ -78,8 +80,12 @@ func CreateUser(file, user, passwd string, algo Hasher) error {
 // using the given name, password and hashing algorithm
 func (pp Passwds) CreateUser(user, passwd string, algo Hasher) error {
 	if _, exists := pp[user]; exists {
-		return fmt.Errorf("user %s already exists", user)
+		return &UserError{
+			Name: user,
+			Err:  ErrExists,
+		}
 	}
+
 	h, err := algo.Hash(passwd)
 	if err != nil {
 		return err
@@ -106,8 +112,12 @@ func UpdateUser(file, user, passwd string, algo Hasher) error {
 // using the given name, password and hashing algorithm
 func (pp Passwds) UpdateUser(user, passwd string, algo Hasher) error {
 	if _, exists := pp[user]; !exists {
-		return fmt.Errorf("user %s does not exist", user)
+		return &UserError{
+			Name: user,
+			Err:  ErrNotExists,
+		}
 	}
+
 	h, err := algo.Hash(passwd)
 	if err != nil {
 		return err
@@ -133,7 +143,10 @@ func DeleteUser(file, user string) error {
 // DeleteUser deletes the named user from the named file
 func (pp Passwds) DeleteUser(user string) error {
 	if _, exists := pp[user]; !exists {
-		return fmt.Errorf("user %s does not exist", user)
+		return &UserError{
+			Name: user,
+			Err:  ErrNotExists,
+		}
 	}
 
 	delete(pp, user)
@@ -154,12 +167,20 @@ func VerifyUser(file, user, passwd string) error {
 // with the given Passwd object
 func (pp Passwds) VerifyUser(user, passwd string) error {
 	if _, ok := pp[user]; !ok {
-		return fmt.Errorf("user %s does not exist", user)
+		return &UserError{
+			Name: user,
+			Err:  ErrNotExists,
+		}
 	}
-	alg, err := identifyHash(pp[user])
-	if err != nil {
-		return fmt.Errorf("cannot identify algo %v", alg)
+
+	alg := identifyHash(pp[user])
+	if alg == nil {
+		return &UserError{
+			Name: user,
+			Err:  ErrInvalidAlgorithm,
+		}
 	}
+
 	return alg.Match(passwd, pp[user])
 }
 
@@ -177,24 +198,24 @@ func (pp Passwds) Bytes() []byte {
 	return pass
 }
 
-func identifyHash(h string) (Hasher, error) {
+func identifyHash(h string) Hasher {
 	switch {
 	case strings.HasPrefix(h, "$2a$"), strings.HasPrefix(h, "$2y$"),
 		strings.HasPrefix(h, "$2x$"), strings.HasPrefix(h, "$2b$"):
-		return new(Bcrypt), nil
+		return new(Bcrypt)
 	case strings.HasPrefix(h, "$apr1$"):
-		return new(Apr1), nil
+		return new(Apr1)
 	case strings.HasPrefix(h, "{SHA}"):
-		return new(Sha), nil
+		return new(Sha)
 	case strings.HasPrefix(h, "{SSHA}"):
-		return new(Ssha), nil
+		return new(Ssha)
 	case strings.HasPrefix(h, "$5$"):
-		return new(Sha256), nil
+		return new(Sha256)
 	case strings.HasPrefix(h, "$6$"):
-		return new(Sha512), nil
+		return new(Sha512)
+	default:
+		return nil
 	}
-
-	return nil, fmt.Errorf("unsupported hash algorithm")
 }
 
 func validLine(parts []string, lineNumber int, line string) (bool, error) {