pes: detect truncated data and error

Author: tmm1

data.go

@@ -84,6 +84,12 @@ func parseData(ps []*Packet, prs PacketsParser, pm *programMap) (ds []*DemuxerDa
 		// Parse PES data
 		var pesData *PESData
 		if pesData, err = parsePESData(i); err != nil {
+			if err == ErrTruncatedPESPackets {
+				// The accumulator gave us all the packets available, but there's still not
+				// enough data. Ignore and keep going.
+				err = nil
+				return
+			}
 			err = fmt.Errorf("astits: parsing PES data failed: %w", err)
 			return
 		}

data_pes.go

@@ -1,6 +1,7 @@
 package astits
 
 import (
+	"errors"
 	"fmt"
 
 	"github.com/asticode/go-astikit"
@@ -36,6 +37,11 @@ const (
 	TrickModeControlSlowReverse = 4
 )
 
+// Errors
+var (
+	ErrTruncatedPESPackets = errors.New("astits: missing data in PES packets")
+)
+
 const (
 	pesHeaderLength    = 6
 	ptsOrDTSByteLength = 5
@@ -115,6 +121,8 @@ func (h *PESHeader) IsVideoStream() bool {
 }
 
 // parsePESData parses a PES data
+// Returns ErrTruncatedPESPackets if the header was parsed, but the
+// advertised PacketLength was not available.
 func parsePESData(i *astikit.BytesIterator) (d *PESData, err error) {
 	// Create data
 	d = &PESData{}
@@ -129,6 +137,11 @@ func parsePESData(i *astikit.BytesIterator) (d *PESData, err error) {
 		return
 	}
 
+	if int(d.Header.PacketLength) > i.Len()-dataStart {
+		err = ErrTruncatedPESPackets
+		return
+	}
+
 	// Seek to data
 	i.Seek(dataStart)