Implement user password checking

internal/wisski/ingredient/php/users/password.go

@@ -0,0 +1,144 @@
+package users
+
+import (
+	"bufio"
+	"context"
+	"embed"
+	"errors"
+	"fmt"
+	"io"
+	"io/fs"
+	"strings"
+
+	"github.com/FAU-CDI/wisski-distillery/internal/phpx"
+)
+
+var errGetValidator = errors.New("GetPasswordValidator: Unknown Error")
+
+func (u *Users) GetPasswordValidator(username string) (pv PasswordValidator, err error) {
+	server := u.PHP.NewServer()
+
+	var hash string
+	err = u.PHP.ExecScript(server, &hash, usersPHP, "get_password_hash", username)
+	if err != nil {
+		server.Close()
+		return pv, err
+	}
+	if len(hash) == 0 {
+		server.Close()
+		return pv, errGetValidator
+	}
+
+	pv.server = server
+	pv.username = username
+	pv.hash = hash
+	return pv, nil
+}
+
+type PasswordValidator struct {
+	server *phpx.Server
+
+	username string
+	hash     string
+}
+
+func (pv PasswordValidator) Close() error {
+	return pv.server.Close()
+}
+
+func (pv PasswordValidator) Check(password string) bool {
+	var result phpx.Boolean
+	err := pv.server.MarshalCall(&result, "check_password_hash", password, string(pv.hash))
+	if err != nil {
+		return false
+	}
+	return bool(result)
+}
+
+var errPasswordUsername = errors.New("username === password")
+
+type CommonPasswordError struct {
+	Password CommonPassword
+}
+
+func (cpe CommonPasswordError) Error() string {
+	return fmt.Sprintf("%q from %q", cpe.Password.Password, cpe.Password.Source)
+}
+
+func (pv PasswordValidator) CheckDictionary(context context.Context, writer io.Writer) error {
+	var counter int
+
+	if pv.Check(pv.username) {
+		if writer != nil {
+			counter++
+			fmt.Fprintln(writer, counter)
+		}
+		return errPasswordUsername
+	}
+	for candidate := range CommonPasswords() {
+		if context.Err() != nil {
+			continue
+		}
+		result := pv.Check(candidate.Password)
+		if writer != nil {
+			counter++
+			fmt.Fprintln(writer, counter)
+		}
+
+		if result {
+			return &CommonPasswordError{Password: candidate}
+		}
+	}
+
+	return context.Err()
+}
+
+//go:embed passwords
+var passwordsEmbed embed.FS
+
+type CommonPassword struct {
+	Password string
+	Source   string
+}
+
+// CommonPasswords returns a channel of most common passwords
+func CommonPasswords() <-chan CommonPassword {
+	pChan := make(chan CommonPassword, 10)
+	go func() {
+		defer close(pChan)
+
+		fs.WalkDir(passwordsEmbed, ".", func(path string, d fs.DirEntry, err error) error {
+			if err != nil {
+				return err
+			}
+
+			// get the full path
+			if d.IsDir() || !strings.HasSuffix(path, ".txt") {
+				return nil
+			}
+
+			// open it
+			file, err := passwordsEmbed.Open(path)
+			if err != nil {
+				return err
+			}
+			defer file.Close()
+
+			// scan it line by line
+			scanner := bufio.NewScanner(file)
+			for scanner.Scan() {
+				line := strings.TrimSpace(scanner.Text())
+				if line == "" || strings.HasPrefix(line, "//") {
+					continue
+				}
+				pChan <- CommonPassword{
+					Password: line,
+					Source:   path,
+				}
+			}
+
+			return scanner.Err()
+		})
+	}()
+	return pChan
+}