refactor stream service helpers

internal/service/stream_hls.go

@@ -0,0 +1,102 @@
+package service
+
+import (
+	"errors"
+	"io"
+	"net/http"
+	"os"
+	"path/filepath"
+	"strings"
+	"time"
+)
+
+// ServeHLSPlaylist makes sure a transcode is running and writes the m3u8.
+// We block (with a 30s timeout) until the playlist file shows up.
+func (s *StreamService) ServeHLSPlaylist(w http.ResponseWriter, r *http.Request, mediaID string) error {
+	// 「客户端直连解码」模式下宿主机不提供转码，HLS 一律拒绝，
+	// 迫使播放器走 direct play 本地解码。
+	if s.directPlayOnly(r.Context()) {
+		return ErrTranscodeDisabled
+	}
+	if _, err := s.transcoder.EnsureJob(r.Context(), mediaID); err != nil {
+		return err
+	}
+	s.transcoder.TouchJob(mediaID)
+	if !s.transcoder.WaitReady(r.Context(), mediaID, 30*time.Second) {
+		return errors.New("hls playlist not ready")
+	}
+	playlist := s.transcoder.PlaylistPath(mediaID)
+	f, err := os.Open(playlist) // #nosec G304 -- playlist path is generated under the transcoder cache directory for this media ID.
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+	stat, _ := f.Stat()
+	w.Header().Set("Content-Type", "application/vnd.apple.mpegurl")
+	w.Header().Set("Cache-Control", "no-cache")
+	w.Header().Set("Content-Disposition", "inline")
+	if r.URL.RawQuery != "" {
+		data, err := io.ReadAll(f)
+		if err != nil {
+			return err
+		}
+		playlist := appendQueryToHLSSegments(string(data), r.URL.RawQuery)
+		_, err = io.WriteString(w, playlist)
+		return err
+	}
+	http.ServeContent(w, r, stat.Name(), stat.ModTime(), f)
+	return nil
+}
+
+func appendQueryToHLSSegments(playlist, rawQuery string) string {
+	if strings.TrimSpace(rawQuery) == "" {
+		return playlist
+	}
+	lines := strings.SplitAfter(playlist, "\n")
+	for i, line := range lines {
+		trimmed := strings.TrimSpace(line)
+		if trimmed == "" || strings.HasPrefix(trimmed, "#") || strings.Contains(trimmed, "?") {
+			continue
+		}
+		if strings.HasSuffix(strings.ToLower(trimmed), ".ts") {
+			lineEnding := ""
+			if strings.HasSuffix(line, "\r\n") {
+				lineEnding = "\r\n"
+			} else if strings.HasSuffix(line, "\n") {
+				lineEnding = "\n"
+			}
+			lines[i] = strings.TrimRight(line, "\r\n") + "?" + rawQuery + lineEnding
+		}
+	}
+	return strings.Join(lines, "")
+}
+
+// ServeHLSSegment writes a single .ts segment from the on-disk cache.
+func (s *StreamService) ServeHLSSegment(w http.ResponseWriter, r *http.Request, mediaID, segment string) error {
+	s.transcoder.TouchJob(mediaID)
+	// Only allow segments that look like seg_NNNNN.ts so we cannot be tricked
+	// into reading arbitrary files via path traversal.
+	if !strings.HasPrefix(segment, "seg_") || !strings.HasSuffix(segment, ".ts") {
+		return errors.New("bad segment")
+	}
+	full := filepath.Join(s.transcoder.HLSDir(mediaID), segment)
+	abs, err := filepath.Abs(full)
+	if err != nil {
+		return err
+	}
+	dir, _ := filepath.Abs(s.transcoder.HLSDir(mediaID))
+	if !pathWithin(abs, dir) {
+		return errors.New("path escape")
+	}
+	f, err := os.Open(abs) // #nosec G304 -- abs is constrained to the HLS cache directory with pathWithin.
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+	stat, _ := f.Stat()
+	w.Header().Set("Content-Type", "video/mp2t")
+	w.Header().Set("Cache-Control", "public, max-age=3600")
+	w.Header().Set("Content-Disposition", "inline")
+	http.ServeContent(w, r, stat.Name(), stat.ModTime(), f)
+	return nil
+}