1 files changed, 111 insertions, 0 deletions
diff --git a/vendor/github.com/pion/dtls/v2/fragment_buffer.go b/vendor/github.com/pion/dtls/v2/fragment_buffer.go
new file mode 100644
index 0000000..0274993
--- /dev/null
+++ b/vendor/github.com/pion/dtls/v2/fragment_buffer.go
@@ -0,0 +1,111 @@
+package dtls
+
+import (
+	"github.com/pion/dtls/v2/pkg/protocol"
+	"github.com/pion/dtls/v2/pkg/protocol/handshake"
+	"github.com/pion/dtls/v2/pkg/protocol/recordlayer"
+)
+
+type fragment struct {
+	recordLayerHeader recordlayer.Header
+	handshakeHeader   handshake.Header
+	data              []byte
+}
+
+type fragmentBuffer struct {
+	// map of MessageSequenceNumbers that hold slices of fragments
+	cache map[uint16][]*fragment
+
+	currentMessageSequenceNumber uint16
+}
+
+func newFragmentBuffer() *fragmentBuffer {
+	return &fragmentBuffer{cache: map[uint16][]*fragment{}}
+}
+
+// Attempts to push a DTLS packet to the fragmentBuffer
+// when it returns true it means the fragmentBuffer has inserted and the buffer shouldn't be handled
+// when an error returns it is fatal, and the DTLS connection should be stopped
+func (f *fragmentBuffer) push(buf []byte) (bool, error) {
+	frag := new(fragment)
+	if err := frag.recordLayerHeader.Unmarshal(buf); err != nil {
+		return false, err
+	}
+
+	// fragment isn't a handshake, we don't need to handle it
+	if frag.recordLayerHeader.ContentType != protocol.ContentTypeHandshake {
+		return false, nil
+	}
+
+	for buf = buf[recordlayer.HeaderSize:]; len(buf) != 0; frag = new(fragment) {
+		if err := frag.handshakeHeader.Unmarshal(buf); err != nil {
+			return false, err
+		}
+
+		if _, ok := f.cache[frag.handshakeHeader.MessageSequence]; !ok {
+			f.cache[frag.handshakeHeader.MessageSequence] = []*fragment{}
+		}
+
+		// end index should be the length of handshake header but if the handshake
+		// was fragmented, we should keep them all
+		end := int(handshake.HeaderLength + frag.handshakeHeader.Length)
+		if size := len(buf); end > size {
+			end = size
+		}
+
+		// Discard all headers, when rebuilding the packet we will re-build
+		frag.data = append([]byte{}, buf[handshake.HeaderLength:end]...)
+		f.cache[frag.handshakeHeader.MessageSequence] = append(f.cache[frag.handshakeHeader.MessageSequence], frag)
+		buf = buf[end:]
+	}
+
+	return true, nil
+}
+
+func (f *fragmentBuffer) pop() (content []byte, epoch uint16) {
+	frags, ok := f.cache[f.currentMessageSequenceNumber]
+	if !ok {
+		return nil, 0
+	}
+
+	// Go doesn't support recursive lambdas
+	var appendMessage func(targetOffset uint32) bool
+
+	rawMessage := []byte{}
+	appendMessage = func(targetOffset uint32) bool {
+		for _, f := range frags {
+			if f.handshakeHeader.FragmentOffset == targetOffset {
+				fragmentEnd := (f.handshakeHeader.FragmentOffset + f.handshakeHeader.FragmentLength)
+				if fragmentEnd != f.handshakeHeader.Length {
+					if !appendMessage(fragmentEnd) {
+						return false
+					}
+				}
+
+				rawMessage = append(f.data, rawMessage...)
+				return true
+			}
+		}
+		return false
+	}
+
+	// Recursively collect up
+	if !appendMessage(0) {
+		return nil, 0
+	}
+
+	firstHeader := frags[0].handshakeHeader
+	firstHeader.FragmentOffset = 0
+	firstHeader.FragmentLength = firstHeader.Length
+
+	rawHeader, err := firstHeader.Marshal()
+	if err != nil {
+		return nil, 0
+	}
+
+	messageEpoch := frags[0].recordLayerHeader.Epoch
+
+	delete(f.cache, f.currentMessageSequenceNumber)
+	f.currentMessageSequenceNumber++
+	return append(rawHeader, rawMessage...), messageEpoch
+}