fix: make qbittorrent login compatible

internal/service/download_clients.go

@@ -8,9 +8,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
-	"io"
 	"net/http"
-	"net/url"
 	"strings"
 	"time"
 
@@ -130,40 +128,7 @@ func (s *DownloadClientService) Test(ctx context.Context, id string) error {
 	}
 	switch c.Type {
 	case "qbittorrent":
-		host := strings.TrimRight(c.Host, "/")
-		body := url.Values{}
-		body.Set("username", c.Username)
-		body.Set("password", c.Password)
-		req, _ := http.NewRequestWithContext(
-			ctx, http.MethodPost,
-			host+"/api/v2/auth/login",
-			strings.NewReader(body.Encode()),
-		)
-		req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
-		// qBittorrent v4.6+ 默认开启 "host header validation" 并要求
-		// Referer 与 Host 同源，否则即使账户正确也会拒绝登录。
-		req.Header.Set("Referer", host)
-		req.Header.Set("Origin", host)
-		req.Header.Set("User-Agent", "MediaStationGo/0.1")
-		resp, err := s.client.Do(req)
-		if err != nil {
-			return err
-		}
-		defer resp.Body.Close()
-		if resp.StatusCode == http.StatusForbidden {
-			return errors.New("qbittorrent: 403 — 用户名/密码错误，或 WebUI 启用了 IP 封禁")
-		}
-		if resp.StatusCode >= 400 {
-			return fmt.Errorf("qbittorrent returned %d", resp.StatusCode)
-		}
-		// 即使返回 200，body 内容仍可能是 "Fails." 表示登录失败。
-		raw, _ := io.ReadAll(io.LimitReader(resp.Body, 256))
-		text := strings.TrimSpace(string(raw))
-		if text == "Fails." {
-			return errors.New("qbittorrent: 用户名/密码错误")
-		}
-		// 正确响应是 "Ok." — 但部分版本会重定向或返回空体，不强校验。
-		return nil
+		return qbitLogin(ctx, s.client, c.Host, c.Username, c.Password)
 	case "aria2", "transmission":
 		req, _ := http.NewRequestWithContext(ctx, http.MethodGet, c.Host, nil)
 		resp, err := s.client.Do(req)

internal/service/qbittorrent.go

@@ -96,36 +96,7 @@ func (q *QBitClient) Login(ctx context.Context) error {
 	if q.cfg.BaseURL == "" {
 		return errors.New("qbittorrent base url not configured")
 	}
-	form := url.Values{}
-	form.Set("username", q.cfg.Username)
-	form.Set("password", q.cfg.Password)
-	req, err := http.NewRequestWithContext(ctx, http.MethodPost,
-		strings.TrimRight(q.cfg.BaseURL, "/")+"/api/v2/auth/login",
-		strings.NewReader(form.Encode()),
-	)
-	if err != nil {
-		return err
-	}
-	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
-	baseURL := strings.TrimRight(q.cfg.BaseURL, "/")
-	req.Header.Set("Referer", baseURL)
-	req.Header.Set("Origin", baseURL)
-	req.Header.Set("User-Agent", "MediaStationGo/0.1")
-
-	resp, err := q.client.Do(req)
-	if err != nil {
-		return err
-	}
-	defer resp.Body.Close()
-	body, _ := io.ReadAll(resp.Body)
-	text := strings.TrimSpace(string(body))
-	if resp.StatusCode == http.StatusForbidden {
-		return errors.New("qbittorrent login forbidden: check username/password, WebUI IP ban, CSRF/Host header validation, and allowed subnets")
-	}
-	if resp.StatusCode >= 400 || text != "Ok." {
-		return fmt.Errorf("qbittorrent login failed: status=%d body=%s", resp.StatusCode, text)
-	}
-	return nil
+	return qbitLogin(ctx, q.client, q.cfg.BaseURL, q.cfg.Username, q.cfg.Password)
 }
 
 // AddTorrent submits a magnet URL or HTTP(S) URL to qBittorrent.

internal/service/qbittorrent_adp.go

@@ -273,33 +273,9 @@ func (a *QBitAdapter) loginLocked(ctx context.Context) error {
 	if a.cfg.Host == "" {
 		return fmt.Errorf("qbittorrent host not configured")
 	}
-	form := url.Values{}
-	form.Set("username", a.cfg.Username)
-	form.Set("password", a.cfg.Password)
-	baseURL := strings.TrimRight(a.cfg.Host, "/")
-	req, err := http.NewRequestWithContext(ctx, http.MethodPost,
-		baseURL+"/api/v2/auth/login", strings.NewReader(form.Encode()))
-	if err != nil {
+	if err := qbitLogin(ctx, a.client, a.cfg.Host, a.cfg.Username, a.cfg.Password); err != nil {
 		return err
 	}
-	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
-	req.Header.Set("Referer", baseURL)
-	req.Header.Set("Origin", baseURL)
-	req.Header.Set("User-Agent", "MediaStationGo/0.1")
-
-	resp, err := a.client.Do(req)
-	if err != nil {
-		return err
-	}
-	defer resp.Body.Close()
-	body, _ := io.ReadAll(resp.Body)
-	text := strings.TrimSpace(string(body))
-	if resp.StatusCode == http.StatusForbidden {
-		return fmt.Errorf("qbittorrent login forbidden: check username/password, WebUI IP ban, CSRF/Host header validation, and allowed subnets")
-	}
-	if resp.StatusCode >= 400 || text != "Ok." {
-		return fmt.Errorf("qbittorrent login failed: status=%d body=%s", resp.StatusCode, text)
-	}
 	a.LoggedIn = true
 	return nil
 }

internal/service/qbittorrent_login.go

@@ -0,0 +1,80 @@
+package service
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"strings"
+)
+
+type qbitLoginVariant struct {
+	name    string
+	referer bool
+	origin  bool
+}
+
+func qbitLogin(ctx context.Context, client *http.Client, baseURL, username, password string) error {
+	baseURL = strings.TrimRight(strings.TrimSpace(baseURL), "/")
+	if baseURL == "" {
+		return errors.New("qbittorrent host not configured")
+	}
+	var lastErr error
+	for _, variant := range []qbitLoginVariant{
+		{name: "minimal"},
+		{name: "referer", referer: true},
+		{name: "referer-origin", referer: true, origin: true},
+	} {
+		err := qbitLoginOnce(ctx, client, baseURL, username, password, variant)
+		if err == nil {
+			return nil
+		}
+		lastErr = err
+		if errors.Is(err, errQbitBadCredentials) {
+			return err
+		}
+	}
+	return lastErr
+}
+
+var errQbitBadCredentials = errors.New("qbittorrent: 用户名/密码错误")
+
+func qbitLoginOnce(ctx context.Context, client *http.Client, baseURL, username, password string, variant qbitLoginVariant) error {
+	form := url.Values{}
+	form.Set("username", username)
+	form.Set("password", password)
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost,
+		baseURL+"/api/v2/auth/login", strings.NewReader(form.Encode()))
+	if err != nil {
+		return err
+	}
+	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
+	if variant.referer {
+		req.Header.Set("Referer", baseURL)
+	}
+	if variant.origin {
+		req.Header.Set("Origin", baseURL)
+	}
+
+	resp, err := client.Do(req)
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+	raw, _ := io.ReadAll(io.LimitReader(resp.Body, 1024))
+	text := strings.TrimSpace(string(raw))
+	switch {
+	case resp.StatusCode == http.StatusOK && text == "Ok.":
+		return nil
+	case resp.StatusCode == http.StatusOK && text == "Fails.":
+		return errQbitBadCredentials
+	case resp.StatusCode == http.StatusForbidden:
+		return fmt.Errorf("qbittorrent: 403 forbidden during %s login, body=%q; check qBittorrent WebUI bypass/auth settings for the container IP and host %s", variant.name, text, baseURL)
+	case resp.StatusCode >= 400:
+		return fmt.Errorf("qbittorrent login failed during %s login: status=%d body=%q", variant.name, resp.StatusCode, text)
+	default:
+		return fmt.Errorf("qbittorrent login unexpected response during %s login: status=%d body=%q", variant.name, resp.StatusCode, text)
+	}
+}

internal/service/qbittorrent_test.go

@@ -5,6 +5,7 @@ import (
 	"io"
 	"mime/multipart"
 	"net/http"
+	"net/http/cookiejar"
 	"net/http/httptest"
 	"strings"
 	"sync/atomic"
@@ -14,6 +15,68 @@ import (
 	"go.uber.org/zap"
 )
 
+func TestQBitLoginUsesMinimalRequestFirst(t *testing.T) {
+	var loginAttempts atomic.Int32
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		switch r.URL.Path {
+		case "/api/v2/auth/login":
+			loginAttempts.Add(1)
+			if r.Header.Get("Origin") != "" || r.Header.Get("Referer") != "" {
+				http.Error(w, "unexpected csrf headers", http.StatusForbidden)
+				return
+			}
+			_, _ = w.Write([]byte("Ok."))
+		default:
+			http.NotFound(w, r)
+		}
+	}))
+	defer server.Close()
+
+	client := NewQBitClient(zap.NewNop(), QBitConfig{
+		BaseURL:  server.URL,
+		Username: "admin",
+		Password: "adminadmin",
+	})
+
+	if err := client.Login(context.Background()); err != nil {
+		t.Fatalf("expected minimal login to succeed: %v", err)
+	}
+	if loginAttempts.Load() != 1 {
+		t.Fatalf("login attempts = %d, want 1", loginAttempts.Load())
+	}
+}
+
+func TestQBitLoginRetriesWithRefererWhenRequired(t *testing.T) {
+	var loginAttempts atomic.Int32
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		switch r.URL.Path {
+		case "/api/v2/auth/login":
+			loginAttempts.Add(1)
+			if r.Header.Get("Referer") == "" {
+				http.Error(w, "missing referer", http.StatusForbidden)
+				return
+			}
+			if r.Header.Get("Origin") != "" {
+				http.Error(w, "origin blocked", http.StatusForbidden)
+				return
+			}
+			_, _ = w.Write([]byte("Ok."))
+		default:
+			http.NotFound(w, r)
+		}
+	}))
+	defer server.Close()
+
+	jar, _ := cookiejar.New(nil)
+	httpClient := &http.Client{Jar: jar}
+	if err := qbitLogin(context.Background(), httpClient, server.URL, "admin", "adminadmin"); err != nil {
+		t.Fatalf("expected referer retry to succeed: %v", err)
+	}
+	if loginAttempts.Load() != 2 {
+		t.Fatalf("login attempts = %d, want 2", loginAttempts.Load())
+	}
+}
+
 func TestQBitAddTorrentRequiresVisibleNewTask(t *testing.T) {
 	oldAttempts := qbitAddVerifyAttempts
 	oldInterval := qbitAddVerifyInterval