webseed/request.go

   1 package webseed
   2
   3 import (
   4         "fmt"
   5         "net/http"
   6         "net/url"
   7         "path"
   8         "strings"
   9
  10         "github.com/anacrolix/torrent/metainfo"
  11 )
  12
  13 func trailingPath(infoName string, pathComps []string) string {
  14         return path.Join(
  15                 func() (ret []string) {
  16                         for _, comp := range append([]string{infoName}, pathComps...) {
  17                                 ret = append(ret, url.QueryEscape(comp))
  18                         }
  19                         return
  20                 }()...,
  21         )
  22 }
  23
  24 // Creates a request per BEP 19.
  25 func NewRequest(url_ string, fileIndex int, info *metainfo.Info, offset, length int64) (*http.Request, error) {
  26         fileInfo := info.UpvertedFiles()[fileIndex]
  27         if strings.HasSuffix(url_, "/") {
  28                 // BEP specifies that we append the file path. We need to escape each component of the path
  29                 // for things like spaces and '#'.
  30                 url_ += trailingPath(info.Name, fileInfo.Path)
  31         }
  32         req, err := http.NewRequest(http.MethodGet, url_, nil)
  33         if err != nil {
  34                 return nil, err
  35         }
  36         if offset != 0 || length != fileInfo.Length {
  37                 req.Header.Set("Range", fmt.Sprintf("bytes=%d-%d", offset, offset+length-1))
  38         }
  39         return req, nil
  40 }