[webseed] Add a custom URL encoder for webseeds

client.go

@@ -1326,7 +1326,7 @@ func (t *Torrent) MergeSpec(spec *TorrentSpec) error {
 	defer cl.unlock()
 	t.initialPieceCheckDisabled = spec.DisableInitialPieceCheck
 	for _, url := range spec.Webseeds {
-		t.addWebSeed(url)
+		t.addWebSeed(url, spec.EncodeWebSeedUrl)
 	}
 	for _, peerAddr := range spec.PeerAddrs {
 		t.addPeer(PeerInfo{

spec.go

@@ -36,6 +36,10 @@ type TorrentSpec struct {
 	// Whether to allow data download or upload
 	DisallowDataUpload   bool
 	DisallowDataDownload bool
+
+	// Custom encoder for webseed URLs
+	// Leave nil to use the default (url.QueryEscape)
+	EncodeWebSeedUrl func(string) string
 }
 
 func TorrentSpecFromMagnetUri(uri string) (spec *TorrentSpec, err error) {

torrent.go

@@ -2350,15 +2350,28 @@ func (t *Torrent) callbacks() *Callbacks {
 	return &t.cl.config.Callbacks
 }
 
-func (t *Torrent) AddWebSeeds(urls []string) {
+type AddWebSeedsOptions struct {
+	// Custom encoder for webseed URLs
+	// Leave nil to use the default (url.QueryEscape)
+	EncodeUrl func(string) string
+}
+
+
+// Add web seeds to the torrent.
+// If AddWebSeedsOptions is not nil, only the first one is used.
+func (t *Torrent) AddWebSeeds(urls []string, opts ...AddWebSeedsOptions) {
 	t.cl.lock()
 	defer t.cl.unlock()
 	for _, u := range urls {
-		t.addWebSeed(u)
+		if opts == nil {
+			t.addWebSeed(u, nil)
+		} else {
+			t.addWebSeed(u, opts[0].EncodeUrl)
+		}
 	}
 }
 
-func (t *Torrent) addWebSeed(url string) {
+func (t *Torrent) addWebSeed(url string, encodeUrl func(string) string) {
 	if t.cl.config.DisableWebseeds {
 		return
 	}
@@ -2395,6 +2408,7 @@ func (t *Torrent) addWebSeed(url string) {
 					r: r,
 				}
 			},
+			EncodeUrl: encodeUrl,
 		},
 		activeRequests: make(map[Request]webseed.Request, maxRequests),
 		maxRequests:    maxRequests,

webseed/client.go

@@ -41,6 +41,11 @@ func (r Request) Cancel() {
 	r.cancel()
 }
 
+type Spec struct {
+	Urls      []string
+	EncodeUrl func(string) string
+}
+
 type Client struct {
 	HttpClient *http.Client
 	Url        string
@@ -52,6 +57,7 @@ type Client struct {
 	// private in the future, if Client ever starts removing pieces.
 	Pieces              roaring.Bitmap
 	ResponseBodyWrapper ResponseBodyWrapper
+	EncodeUrl           func(string) string
 }
 
 type ResponseBodyWrapper func(io.Reader) io.Reader
@@ -76,7 +82,10 @@ func (ws *Client) NewRequest(r RequestSpec) Request {
 	ctx, cancel := context.WithCancel(context.Background())
 	var requestParts []requestPart
 	if !ws.fileIndex.Locate(r, func(i int, e segments.Extent) bool {
-		req, err := NewRequest(ws.Url, i, ws.info, e.Start, e.Length)
+		req, err := NewRequestWithCustomUrlEncoding(
+			ws.Url, i, ws.info, e.Start, e.Length,
+			ws.EncodeUrl,
+		)
 		if err != nil {
 			panic(err)
 		}

webseed/request.go

@@ -12,28 +12,56 @@ import (
 
 // Escapes path name components suitable for appending to a webseed URL. This works for converting
 // S3 object keys to URLs too.
+// Contrary to the name, this actually does a QueryEscape, rather than a
+// PathEscape. This works better with most S3 providers. You can use
+// EscapePathWithCustomEncoding for a custom encoding.
 func EscapePath(pathComps []string) string {
+	return escapePath(pathComps, nil)
+}
+
+func escapePath(pathComps []string, encodeUrl func(string) string) string {
+	if encodeUrl == nil {
+		encodeUrl = url.QueryEscape
+	}
 	return path.Join(
 		func() (ret []string) {
 			for _, comp := range pathComps {
-				ret = append(ret, url.QueryEscape(comp))
+				ret = append(ret, encodeUrl(comp))
 			}
 			return
 		}()...,
 	)
 }
 
-func trailingPath(infoName string, fileComps []string) string {
-	return EscapePath(append([]string{infoName}, fileComps...))
+func trailingPath(infoName string, fileComps []string, encodeUrl func(string) string) string {
+	return escapePath(append([]string{infoName}, fileComps...), encodeUrl)
 }
 
 // Creates a request per BEP 19.
 func NewRequest(url_ string, fileIndex int, info *metainfo.Info, offset, length int64) (*http.Request, error) {
+	return newRequest(url_, fileIndex, info, offset, length, nil)
+}
+
+func NewRequestWithCustomUrlEncoding(
+	url_ string, fileIndex int,
+	info *metainfo.Info,
+	offset, length int64,
+	encodeUrl func(string) string,
+) (*http.Request, error) {
+	return newRequest(url_, fileIndex, info, offset, length, encodeUrl)
+}
+
+func newRequest(
+	url_ string, fileIndex int,
+	info *metainfo.Info,
+	offset, length int64,
+	encodeUrl func(string) string,
+) (*http.Request, error) {
 	fileInfo := info.UpvertedFiles()[fileIndex]
 	if strings.HasSuffix(url_, "/") {
 		// BEP specifies that we append the file path. We need to escape each component of the path
 		// for things like spaces and '#'.
-		url_ += trailingPath(info.Name, fileInfo.Path)
+		url_ += trailingPath(info.Name, fileInfo.Path, encodeUrl)
 	}
 	req, err := http.NewRequest(http.MethodGet, url_, nil)
 	if err != nil {

webseed/request_test.go

@@ -10,7 +10,7 @@ import (
 func TestTrailingPath(t *testing.T) {
 	c := qt.New(t)
 	test := func(parts []string, result string) {
-		unescaped, err := url.QueryUnescape(trailingPath(parts[0], parts[1:]))
+		unescaped, err := url.QueryUnescape(trailingPath(parts[0], parts[1:], url.QueryEscape))
 		if !c.Check(err, qt.IsNil) {
 			return
 		}
@@ -23,7 +23,7 @@ func TestTrailingPath(t *testing.T) {
 }
 
 func TestTrailingPathForEmptyInfoName(t *testing.T) {
-	qt.Check(t, trailingPath("", []string{`ノ┬─┬ノ ︵ ( \o°o)\`}), qt.Equals, "%E3%83%8E%E2%94%AC%E2%94%80%E2%94%AC%E3%83%8E+%EF%B8%B5+%28+%5Co%C2%B0o%29%5C")
-	qt.Check(t, trailingPath("", []string{"hello", "world"}), qt.Equals, "hello/world")
-	qt.Check(t, trailingPath("war", []string{"and", "peace"}), qt.Equals, "war/and/peace")
+	qt.Check(t, trailingPath("", []string{`ノ┬─┬ノ ︵ ( \o°o)\`}, url.QueryEscape), qt.Equals, "%E3%83%8E%E2%94%AC%E2%94%80%E2%94%AC%E3%83%8E+%EF%B8%B5+%28+%5Co%C2%B0o%29%5C")
+	qt.Check(t, trailingPath("", []string{"hello", "world"}, url.QueryEscape), qt.Equals, "hello/world")
+	qt.Check(t, trailingPath("war", []string{"and", "peace"}, url.QueryEscape), qt.Equals, "war/and/peace")
 }