136 lines
3.5 KiB
Go
136 lines
3.5 KiB
Go
// Copyright 2018, Google
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package pyre
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import (
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"fmt"
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"io"
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"net/http"
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"strconv"
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"strings"
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)
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type DownloadableObject interface {
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Size() int64
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Reader() io.ReaderAt
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io.Closer
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}
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type DownloadManager interface {
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ObjectByName(bucketID, name string) (DownloadableObject, error)
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GetBucketID(bucket string) (string, error)
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GetBucket(id string) ([]byte, error)
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}
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type downloadServer struct {
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dm DownloadManager
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}
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type downloadRequest struct {
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off, n int64
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}
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func parseDownloadHeaders(r *http.Request) (*downloadRequest, error) {
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rang := r.Header.Get("Range")
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if rang == "" {
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return &downloadRequest{}, nil
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}
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if !strings.HasPrefix(rang, "bytes=") {
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return nil, fmt.Errorf("unknown range format: %q", rang)
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}
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rang = strings.TrimPrefix(rang, "bytes=")
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if !strings.Contains(rang, "-") {
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return nil, fmt.Errorf("unknown range format: %q", rang)
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}
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parts := strings.Split(rang, "-")
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off, err := strconv.ParseInt(parts[0], 10, 64)
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if err != nil {
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return nil, err
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}
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end, err := strconv.ParseInt(parts[1], 10, 64)
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if err != nil {
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return nil, err
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}
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return &downloadRequest{
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off: off,
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n: (end + 1) - off,
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}, nil
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}
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func (fs *downloadServer) serveWholeObject(rw http.ResponseWriter, obj DownloadableObject) {
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rw.Header().Set("Content-Length", fmt.Sprintf("%d", obj.Size()))
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sr := io.NewSectionReader(obj.Reader(), 0, obj.Size())
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if _, err := io.Copy(rw, sr); err != nil {
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http.Error(rw, err.Error(), 503)
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fmt.Println("no reader", err)
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}
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}
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func (fs *downloadServer) servePartialObject(rw http.ResponseWriter, obj DownloadableObject, off, len int64) {
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if off >= obj.Size() {
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http.Error(rw, "hell naw", 416)
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fmt.Printf("range not good (%d-%d for %d)\n", off, len, obj.Size())
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return
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}
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if off+len > obj.Size() {
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len = obj.Size() - off
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}
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sr := io.NewSectionReader(obj.Reader(), off, len)
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rw.Header().Set("Content-Length", fmt.Sprintf("%d", len))
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rw.WriteHeader(206) // this goes after headers are set
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if _, err := io.Copy(rw, sr); err != nil {
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fmt.Println("bad read:", err)
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}
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}
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func (fs *downloadServer) ServeHTTP(rw http.ResponseWriter, r *http.Request) {
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req, err := parseDownloadHeaders(r)
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if err != nil {
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http.Error(rw, err.Error(), 503)
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fmt.Println("weird header")
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return
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}
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path := strings.TrimPrefix(r.URL.Path, "/")
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parts := strings.Split(path, "/")
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if len(parts) < 3 {
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http.Error(rw, err.Error(), 404)
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fmt.Println("weird file")
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return
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}
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bucket := parts[1]
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bid, err := fs.dm.GetBucketID(bucket)
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if err != nil {
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http.Error(rw, err.Error(), 503)
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fmt.Println("no bucket:", err)
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return
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}
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file := strings.Join(parts[2:], "/")
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obj, err := fs.dm.ObjectByName(bid, file)
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if err != nil {
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http.Error(rw, err.Error(), 503)
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fmt.Println("no reader", err)
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return
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}
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defer obj.Close()
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if req.off == 0 && req.n == 0 {
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fs.serveWholeObject(rw, obj)
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return
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}
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fs.servePartialObject(rw, obj, req.off, req.n)
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}
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func RegisterDownloadManagerOnMux(d DownloadManager, mux *http.ServeMux) {
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mux.Handle("/file/", &downloadServer{dm: d})
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}
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