1 files changed, 142 insertions, 0 deletions
diff --git a/vendor/github.com/pion/sctp/chunk_selective_ack.go b/vendor/github.com/pion/sctp/chunk_selective_ack.go
new file mode 100644
index 0000000..920d562
--- /dev/null
+++ b/vendor/github.com/pion/sctp/chunk_selective_ack.go
@@ -0,0 +1,142 @@
+package sctp
+
+import (
+	"encoding/binary"
+	"fmt"
+
+	"github.com/pkg/errors"
+)
+
+/*
+chunkSelectiveAck represents an SCTP Chunk of type SACK
+
+This chunk is sent to the peer endpoint to acknowledge received DATA
+chunks and to inform the peer endpoint of gaps in the received
+subsequences of DATA chunks as represented by their TSNs.
+0                   1                   2                   3
+0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+|   Type = 3    |Chunk  Flags   |      Chunk Length             |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+|                      Cumulative TSN Ack                       |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+|          Advertised Receiver Window Credit (a_rwnd)           |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+| Number of Gap Ack Blocks = N  |  Number of Duplicate TSNs = X |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+|  Gap Ack Block #1 Start       |   Gap Ack Block #1 End        |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+/                                                               /
+\                              ...                              \
+/                                                               /
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+|   Gap Ack Block #N Start      |  Gap Ack Block #N End         |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+|                       Duplicate TSN 1                         |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+/                                                               /
+\                              ...                              \
+/                                                               /
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+|                       Duplicate TSN X                         |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+*/
+
+type gapAckBlock struct {
+	start uint16
+	end   uint16
+}
+
+// String makes gapAckBlock printable
+func (g gapAckBlock) String() string {
+	return fmt.Sprintf("%d - %d", g.start, g.end)
+}
+
+type chunkSelectiveAck struct {
+	chunkHeader
+	cumulativeTSNAck               uint32
+	advertisedReceiverWindowCredit uint32
+	gapAckBlocks                   []gapAckBlock
+	duplicateTSN                   []uint32
+}
+
+const (
+	selectiveAckHeaderSize = 12
+)
+
+func (s *chunkSelectiveAck) unmarshal(raw []byte) error {
+	if err := s.chunkHeader.unmarshal(raw); err != nil {
+		return err
+	}
+
+	if s.typ != ctSack {
+		return errors.Errorf("ChunkType is not of type SACK, actually is %s", s.typ.String())
+	}
+
+	if len(s.raw) < selectiveAckHeaderSize {
+		return errors.Errorf("SACK Chunk size is not large enough to contain header (%v remaining, needs %v bytes)",
+			len(s.raw), selectiveAckHeaderSize)
+	}
+
+	s.cumulativeTSNAck = binary.BigEndian.Uint32(s.raw[0:])
+	s.advertisedReceiverWindowCredit = binary.BigEndian.Uint32(s.raw[4:])
+	s.gapAckBlocks = make([]gapAckBlock, binary.BigEndian.Uint16(s.raw[8:]))
+	s.duplicateTSN = make([]uint32, binary.BigEndian.Uint16(s.raw[10:]))
+
+	if len(s.raw) != selectiveAckHeaderSize+(4*len(s.gapAckBlocks)+(4*len(s.duplicateTSN))) {
+		return errors.Errorf("SACK Chunk size does not match predicted amount from header values")
+	}
+
+	offset := selectiveAckHeaderSize
+	for i := range s.gapAckBlocks {
+		s.gapAckBlocks[i].start = binary.BigEndian.Uint16(s.raw[offset:])
+		s.gapAckBlocks[i].end = binary.BigEndian.Uint16(s.raw[offset+2:])
+		offset += 4
+	}
+	for i := range s.duplicateTSN {
+		s.duplicateTSN[i] = binary.BigEndian.Uint32(s.raw[offset:])
+		offset += 4
+	}
+
+	return nil
+}
+
+func (s *chunkSelectiveAck) marshal() ([]byte, error) {
+	sackRaw := make([]byte, selectiveAckHeaderSize+(4*len(s.gapAckBlocks)+(4*len(s.duplicateTSN))))
+	binary.BigEndian.PutUint32(sackRaw[0:], s.cumulativeTSNAck)
+	binary.BigEndian.PutUint32(sackRaw[4:], s.advertisedReceiverWindowCredit)
+	binary.BigEndian.PutUint16(sackRaw[8:], uint16(len(s.gapAckBlocks)))
+	binary.BigEndian.PutUint16(sackRaw[10:], uint16(len(s.duplicateTSN)))
+	offset := selectiveAckHeaderSize
+	for _, g := range s.gapAckBlocks {
+		binary.BigEndian.PutUint16(sackRaw[offset:], g.start)
+		binary.BigEndian.PutUint16(sackRaw[offset+2:], g.end)
+		offset += 4
+	}
+	for _, t := range s.duplicateTSN {
+		binary.BigEndian.PutUint32(sackRaw[offset:], t)
+		offset += 4
+	}
+
+	s.chunkHeader.typ = ctSack
+	s.chunkHeader.raw = sackRaw
+	return s.chunkHeader.marshal()
+}
+
+func (s *chunkSelectiveAck) check() (abort bool, err error) {
+	return false, nil
+}
+
+// String makes chunkSelectiveAck printable
+func (s *chunkSelectiveAck) String() string {
+	res := fmt.Sprintf("SACK cumTsnAck=%d arwnd=%d dupTsn=%d",
+		s.cumulativeTSNAck,
+		s.advertisedReceiverWindowCredit,
+		s.duplicateTSN)
+
+	for _, gap := range s.gapAckBlocks {
+		res = fmt.Sprintf("%s\n gap ack: %s", res, gap)
+	}
+
+	return res
+}