feat: support arbitrary URL proxy via single token

Allow proxying to any URL through the single-token auth path:
- /TOKEN/https://target.com/path
- /TOKEN/https:/target.com/path (browser-normalized)
- /TOKEN/target.com/path (auto-prefixed with https:// for known domains)

Also fix single-mode path handling that previously dropped
parts[2] when SplitN produced 3 parts.

via [HAPI](https://hapi.run)

Co-Authored-By: HAPI <[email protected]>

cmd/main.go

@@ -16,6 +16,80 @@ import (
 	"mirror-proxy/internal/proxy"
 )
 
+import (
+	"net/url"
+)
+
+// extractTargetURL 从请求路径中提取目标 URL
+// 支持格式: /https://target.com/path 或 /http://target.com/path 或 /target.com/path
+// 如果匹配，修改 r.URL.Path 为目标路径并返回目标 URL
+func extractTargetURL(r *http.Request) (string, bool) {
+	path := strings.TrimPrefix(r.URL.Path, "/")
+
+	// 完整 URL 格式: https://... 或 http://...
+	if strings.HasPrefix(path, "https://") {
+		u, err := url.Parse(path)
+		if err == nil {
+			r.URL.Path = u.Path
+			if u.RawQuery != "" {
+				r.URL.RawQuery = u.RawQuery
+			}
+			return path, true
+		}
+	}
+	if strings.HasPrefix(path, "http://") {
+		u, err := url.Parse(path)
+		if err == nil {
+			r.URL.Path = u.Path
+			if u.RawQuery != "" {
+				r.URL.RawQuery = u.RawQuery
+			}
+			return path, true
+		}
+	}
+
+	// 浏览器规范化后的格式: https:/... 或 http:/...
+	if strings.HasPrefix(path, "https:/") {
+		targetURL := "https://" + strings.TrimPrefix(path, "https:/")
+		u, err := url.Parse(targetURL)
+		if err == nil {
+			r.URL.Path = u.Path
+			if u.RawQuery != "" {
+				r.URL.RawQuery = u.RawQuery
+			}
+			return targetURL, true
+		}
+	}
+	if strings.HasPrefix(path, "http:/") {
+		targetURL := "http://" + strings.TrimPrefix(path, "http:/")
+		u, err := url.Parse(targetURL)
+		if err == nil {
+			r.URL.Path = u.Path
+			if u.RawQuery != "" {
+				r.URL.RawQuery = u.RawQuery
+			}
+			return targetURL, true
+		}
+	}
+
+	// 无协议前缀的域名
+	if strings.HasPrefix(path, "github.com/") ||
+		strings.HasPrefix(path, "raw.githubusercontent.com/") ||
+		strings.HasPrefix(path, "api.github.com/") {
+		targetURL := "https://" + path
+		u, err := url.Parse(targetURL)
+		if err == nil {
+			r.URL.Path = u.Path
+			if u.RawQuery != "" {
+				r.URL.RawQuery = u.RawQuery
+			}
+			return targetURL, true
+		}
+	}
+
+	return "", false
+}
+
 func buildHandler(cfg *config.Config) (*admin.Handler, http.Handler) {
 	rl := auth.NewRateLimiter()
 	adminHandler := admin.NewHandler(cfg)
@@ -78,6 +152,12 @@ func buildHandler(cfg *config.Config) (*admin.Handler, http.Handler) {
 			return
 		}
 
+		// URL 代理模式: /https://target.com/path 或 /target.com/path
+		if targetURL, isURL := extractTargetURL(r); isURL {
+			proxy.DynamicProxy(targetURL).ServeHTTP(w, r)
+			return
+		}
+
 		switch link.Type {
 		case "docker":
 			dockerProxy.ServeHTTP(w, r)

internal/auth/auth.go

@@ -152,7 +152,7 @@ func ProxyAuthMiddleware(rl *RateLimiter) func(http.Handler) http.Handler {
 					if len(parts) == 1 {
 						newPath = "/"
 					} else {
-						newPath = "/" + parts[1]
+						newPath = "/" + strings.Join(parts[1:], "/")
 					}
 				}
 			}

internal/proxy/dynamic.go

@@ -0,0 +1,45 @@
+package proxy
+
+import (
+	"fmt"
+	"net/http"
+	"net/http/httputil"
+	"net/url"
+	"time"
+)
+
+// DynamicProxy 创建指向任意目标 URL 的反向代理
+func DynamicProxy(targetURL string) http.Handler {
+	target, err := url.Parse(targetURL)
+	if err != nil {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			http.Error(w, "Invalid target URL", http.StatusBadRequest)
+		})
+	}
+
+	p := &httputil.ReverseProxy{
+		Director: func(req *http.Request) {
+			req.URL.Scheme = target.Scheme
+			req.URL.Host = target.Host
+			req.Host = target.Host
+			req.Header.Set("Host", target.Host)
+			if req.Header.Get("User-Agent") == "" {
+				req.Header.Set("User-Agent", "MirrorProxy/1.0")
+			}
+			req.Header.Del("X-Forwarded-For")
+		},
+		ErrorHandler: func(w http.ResponseWriter, r *http.Request, err error) {
+			w.Header().Set("Content-Type", "text/plain; charset=utf-8")
+			w.WriteHeader(http.StatusBadGateway)
+			fmt.Fprintf(w, "Proxy error: %s", err.Error())
+		},
+		Transport: &http.Transport{
+			MaxIdleConns:        100,
+			MaxIdleConnsPerHost: 20,
+			IdleConnTimeout:     90 * time.Second,
+			TLSHandshakeTimeout: 10 * time.Second,
+		},
+	}
+
+	return p
+}