Add RTP packet dissector

protocol/logger.go

@@ -0,0 +1,27 @@
+/* Copyright (c) 2018 Gregor Riepl
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package protocol
+
+import (
+	"github.com/onitake/restreamer/util"
+)
+
+const (
+	moduleProtocol = "protocol"
+)
+
+var logger util.Logger = util.NewGlobalModuleLogger(moduleProtocol, nil)

protocol/rtp.go

@@ -0,0 +1,180 @@
+/* Copyright (c) 2019 Gregor Riepl
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package protocol
+
+import (
+	"encoding/binary"
+	"errors"
+	"io"
+)
+
+const (
+	DefaultRtpPacketSize int = 1500
+	minHeaderSize int = 12
+)
+
+var (
+	ErrInvalidRtpPacketSize = errors.New("Invalid RTP packet size")
+	ErrInvalidRtpVersion = errors.New("Invalid RTP version")
+)
+
+type RtpPayloadType uint8
+const (
+	RtpPayloadTypePCMU RtpPayloadType = 0
+	RtpPayloadTypeGSM RtpPayloadType = 3
+	RtpPayloadTypeG723 RtpPayloadType = 4
+	RtpPayloadTypeDVI4 RtpPayloadType = 5
+	RtpPayloadTypeDVI4_2 RtpPayloadType = 6
+	RtpPayloadTypeLPC RtpPayloadType = 7
+	RtpPayloadTypePCMA RtpPayloadType = 8
+	RtpPayloadTypeG722 RtpPayloadType = 9
+	RtpPayloadTypeL16 RtpPayloadType = 10
+	RtpPayloadTypeL16_2 RtpPayloadType = 11
+	RtpPayloadTypeQCELP RtpPayloadType = 12
+	RtpPayloadTypeCN RtpPayloadType = 13
+	RtpPayloadTypeMPA RtpPayloadType = 14
+	RtpPayloadTypeG728 RtpPayloadType = 15
+	RtpPayloadTypeDVI4_3 RtpPayloadType = 16
+	RtpPayloadTypeDVI4_4 RtpPayloadType = 17
+	RtpPayloadTypeG729 RtpPayloadType = 18
+	RtpPayloadTypeCelB RtpPayloadType = 25
+	RtpPayloadTypeJPEG RtpPayloadType = 26
+	RtpPayloadTypeNV RtpPayloadType = 28
+	RtpPayloadTypeH261 RtpPayloadType = 31
+	RtpPayloadTypeMPV RtpPayloadType = 32
+	RtpPayloadTypeMP2T RtpPayloadType = 33
+	RtpPayloadTypeH263 RtpPayloadType = 34
+)
+
+// RtpPacket represents a decoded RTP packet.
+// The header fields are dissected, while the payload is contained as a byte slice.
+type RtpPacket struct {
+	// Version contains the RTP protocol version.
+	// Only version 2 is supported.
+	Version uint8
+	// Padding is true if the packet hat the padding flag set.
+	// The extension header and/or payload is always truncated to the actual size.
+	Padding bool
+	// Marker is true if the packet hat the marker bit set.
+	Marker bool
+	// PayloadType describes the kind of data contained in the packet.
+	// See the RtpPayloadType constants for known values. Not that some ranges
+	// are dynamically assigned and must be defined by the application.
+	PayloadType RtpPayloadType
+	// SequenceNumber is a 16-bit sequence number that helps with correct ordering
+	// wen reassembling the stream.
+	SequenceNumber uint16
+	// Timestamp is an application-defined absolute timestamp that should be
+	// used as the basis for ES timestamps. It can also be ignored if the
+	// packaged protocol has sufficiently well-defined timestamps.
+	Timestamp uint32
+	// Ssrc contains the value of the SSRC field.
+	Ssrc uint32
+	// Csrc contains the values of the CSRC fields.
+	// If the packet had no CSRCs, it is an empty list (nil).
+	Csrc []uint32
+	// Extension contains the full extension header, including the length and ... fields.
+	Extension []byte
+	// Payload contains the actual data part of the packet.
+	// It is truncated to the packet size, excluding padding (if it was enabled)
+	Payload []byte
+}
+
+// RtpReader is a packet reader on top of an underlying standard reader.
+// It has a configurable maximum packet size.
+type RtpReader struct {
+	// Reader is the underlying I/O facility
+	Reader io.Reader
+	// PacketSize is the maximum packet size that can be read.
+	// If zero, a default packet size of 1500 octets will be used.
+	PacketSize int
+}
+
+// ReadRtpPacket reads and returns one RTP packet from the underlying reader.
+//
+// If the packet was larger than the maximum packet size, excess data will be dropped.
+// An incomplete packet, together with a non-nil error will be returned in this case.
+//
+// If the buffer was to small to read even the RTP header, a nil packet along with
+// ErrInvalidRtpPacket will be returned.
+//
+// If the prtocol version is not equal to 2, ErrInvalidRtpVersion is returned.
+func (r *RtpReader) ReadRtpPacket() (*RtpPacket, error) {
+	p := &RtpPacket{}
+
+	psize := r.PacketSize
+	if psize == 0 {
+		psize = DefaultRtpPacketSize
+	}
+	data := make([]byte, psize)
+	n, err := r.Reader.Read(data)
+	if n == 0 && err != nil {
+		return nil, err
+	}
+	if n < minHeaderSize {
+		return nil, ErrInvalidRtpPacketSize
+	}
+
+	p.Version = (data[0] & 0xc0) >> 6
+	if p.Version != 2 {
+		logger.Logkv(
+			"event", "error",
+			"error", "rtp_version",
+			"version", p.Version,
+			"message", "Invalid RTP version",
+		)
+		return nil, ErrInvalidRtpVersion
+	}
+	p.Padding = data[0] & 0x20 != 0
+	p.Marker = data[1] & 0x80 != 0
+
+	extension := data[0] & 0x10 != 0
+	csrcc := int(data[0] & 0x0f)
+	xhlen := 0
+	if extension {
+		xhlen = 4
+	}
+	if n < minHeaderSize + 4 * csrcc + xhlen {
+		return nil, ErrInvalidRtpPacketSize
+	}
+
+	p.PayloadType = RtpPayloadType(data[1])
+	p.SequenceNumber = binary.BigEndian.Uint16(data[2:4])
+	p.Timestamp = binary.BigEndian.Uint32(data[4:8])
+	p.Ssrc = binary.BigEndian.Uint32(data[8:12])
+	p.Csrc = make([]uint32, csrcc)
+	offset := minHeaderSize
+
+	for i := 0; i < csrcc; i++ {
+		p.Csrc[i] = binary.BigEndian.Uint32(data[offset:(offset+4)])
+		offset += 4
+	}
+
+	if extension {
+		xlen := int(binary.BigEndian.Uint16(data[(offset+2):(offset+4)]))
+		if n < offset + 4 + xlen {
+			return nil, ErrInvalidRtpPacketSize
+		}
+		p.Extension = data[offset:(offset+4+xlen)]
+		offset += 4 + xlen
+	}
+
+	// TODO truncate padding
+	p.Payload = data[offset:n]
+
+	return p, nil
+}