feat: file proxy handle

server/middlewares/down.go

@@ -0,0 +1,54 @@
+package middlewares
+
+import (
+	"github.com/alist-org/alist/v3/internal/db"
+	"github.com/alist-org/alist/v3/internal/errs"
+	"github.com/alist-org/alist/v3/internal/model"
+	"github.com/alist-org/alist/v3/internal/sign"
+	"github.com/alist-org/alist/v3/pkg/utils"
+	"github.com/alist-org/alist/v3/server/common"
+	"github.com/gin-gonic/gin"
+	"github.com/pkg/errors"
+	stdpath "path"
+)
+
+func Down(c *gin.Context) {
+	rawPath := parsePath(c.Param("path"))
+	c.Set("path", rawPath)
+	filename := stdpath.Base(rawPath)
+	meta, err := db.GetNearestMeta(rawPath)
+	if err != nil {
+		if !errors.Is(errors.Cause(err), errs.MetaNotFound) {
+			common.ErrorResp(c, err, 500, true)
+			return
+		}
+	}
+	c.Set("meta", meta)
+	// verify sign
+	if needSign(meta, rawPath) {
+		s := c.Param("sign")
+		err = sign.Verify(filename, s)
+		if err != nil {
+			common.ErrorResp(c, err, 401)
+			c.Abort()
+			return
+		}
+	}
+	c.Next()
+}
+
+// TODO: implement
+// path maybe contains # ? etc.
+func parsePath(path string) string {
+	return utils.StandardizePath(path)
+}
+
+func needSign(meta *model.Meta, path string) bool {
+	if meta == nil || meta.Password == "" {
+		return false
+	}
+	if !meta.SubFolder && path != meta.Path {
+		return false
+	}
+	return true
+}