1 files changed, 178 insertions, 0 deletions
diff --git a/vendor/github.com/pion/sctp/packet.go b/vendor/github.com/pion/sctp/packet.go
new file mode 100644
index 0000000..dcc650b
--- /dev/null
+++ b/vendor/github.com/pion/sctp/packet.go
@@ -0,0 +1,178 @@
+package sctp
+
+import (
+	"encoding/binary"
+	"fmt"
+	"hash/crc32"
+
+	"github.com/pkg/errors"
+)
+
+// Create the crc32 table we'll use for the checksum
+var castagnoliTable = crc32.MakeTable(crc32.Castagnoli) // nolint:gochecknoglobals
+
+// Allocate and zero this data once.
+// We need to use it for the checksum and don't want to allocate/clear each time.
+var fourZeroes [4]byte // nolint:gochecknoglobals
+
+/*
+Packet represents an SCTP packet, defined in https://tools.ietf.org/html/rfc4960#section-3
+An SCTP packet is composed of a common header and chunks.  A chunk
+contains either control information or user data.
+
+
+                      SCTP Packet Format
+ 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
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+|                        Common Header                          |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+|                          Chunk #1                             |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+|                           ...                                 |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+|                          Chunk #n                             |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+
+                SCTP Common Header Format
+
+ 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
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+|     Source Value Number        |     Destination Value Number   |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+|                      Verification Tag                         |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+|                           Checksum                            |
++-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+
+
+*/
+type packet struct {
+	sourcePort      uint16
+	destinationPort uint16
+	verificationTag uint32
+	chunks          []chunk
+}
+
+const (
+	packetHeaderSize = 12
+)
+
+func (p *packet) unmarshal(raw []byte) error {
+	if len(raw) < packetHeaderSize {
+		return errors.Errorf("raw only %d bytes, %d is the minimum length for a SCTP packet", len(raw), packetHeaderSize)
+	}
+
+	p.sourcePort = binary.BigEndian.Uint16(raw[0:])
+	p.destinationPort = binary.BigEndian.Uint16(raw[2:])
+	p.verificationTag = binary.BigEndian.Uint32(raw[4:])
+
+	offset := packetHeaderSize
+	for {
+		// Exact match, no more chunks
+		if offset == len(raw) {
+			break
+		} else if offset+chunkHeaderSize > len(raw) {
+			return errors.Errorf("Unable to parse SCTP chunk, not enough data for complete header: offset %d remaining %d", offset, len(raw))
+		}
+
+		var c chunk
+		switch chunkType(raw[offset]) {
+		case ctInit:
+			c = &chunkInit{}
+		case ctInitAck:
+			c = &chunkInitAck{}
+		case ctAbort:
+			c = &chunkAbort{}
+		case ctCookieEcho:
+			c = &chunkCookieEcho{}
+		case ctCookieAck:
+			c = &chunkCookieAck{}
+		case ctHeartbeat:
+			c = &chunkHeartbeat{}
+		case ctPayloadData:
+			c = &chunkPayloadData{}
+		case ctSack:
+			c = &chunkSelectiveAck{}
+		case ctReconfig:
+			c = &chunkReconfig{}
+		case ctForwardTSN:
+			c = &chunkForwardTSN{}
+		case ctError:
+			c = &chunkError{}
+		default:
+			return errors.Errorf("Failed to unmarshal, contains unknown chunk type %s", chunkType(raw[offset]).String())
+		}
+
+		if err := c.unmarshal(raw[offset:]); err != nil {
+			return err
+		}
+
+		p.chunks = append(p.chunks, c)
+		chunkValuePadding := getPadding(c.valueLength())
+		offset += chunkHeaderSize + c.valueLength() + chunkValuePadding
+	}
+	theirChecksum := binary.LittleEndian.Uint32(raw[8:])
+	ourChecksum := generatePacketChecksum(raw)
+	if theirChecksum != ourChecksum {
+		return errors.Errorf("Checksum mismatch theirs: %d ours: %d", theirChecksum, ourChecksum)
+	}
+	return nil
+}
+
+func (p *packet) marshal() ([]byte, error) {
+	raw := make([]byte, packetHeaderSize)
+
+	// Populate static headers
+	// 8-12 is Checksum which will be populated when packet is complete
+	binary.BigEndian.PutUint16(raw[0:], p.sourcePort)
+	binary.BigEndian.PutUint16(raw[2:], p.destinationPort)
+	binary.BigEndian.PutUint32(raw[4:], p.verificationTag)
+
+	// Populate chunks
+	for _, c := range p.chunks {
+		chunkRaw, err := c.marshal()
+		if err != nil {
+			return nil, err
+		}
+		raw = append(raw, chunkRaw...)
+
+		paddingNeeded := getPadding(len(raw))
+		if paddingNeeded != 0 {
+			raw = append(raw, make([]byte, paddingNeeded)...)
+		}
+	}
+
+	// Checksum is already in BigEndian
+	// Using LittleEndian.PutUint32 stops it from being flipped
+	binary.LittleEndian.PutUint32(raw[8:], generatePacketChecksum(raw))
+	return raw, nil
+}
+
+func generatePacketChecksum(raw []byte) (sum uint32) {
+	// Fastest way to do a crc32 without allocating.
+	sum = crc32.Update(sum, castagnoliTable, raw[0:8])
+	sum = crc32.Update(sum, castagnoliTable, fourZeroes[:])
+	sum = crc32.Update(sum, castagnoliTable, raw[12:])
+	return sum
+}
+
+// String makes packet printable
+func (p *packet) String() string {
+	format := `Packet:
+	sourcePort: %d
+	destinationPort: %d
+	verificationTag: %d
+	`
+	res := fmt.Sprintf(format,
+		p.sourcePort,
+		p.destinationPort,
+		p.verificationTag,
+	)
+	for i, chunk := range p.chunks {
+		res += fmt.Sprintf("Chunk %d:\n %s", i, chunk)
+	}
+	return res
+}