1 files changed, 77 insertions, 0 deletions
diff --git a/vendor/github.com/pion/srtp/v2/srtcp.go b/vendor/github.com/pion/srtp/v2/srtcp.go
new file mode 100644
index 0000000..dbf5125
--- /dev/null
+++ b/vendor/github.com/pion/srtp/v2/srtcp.go
@@ -0,0 +1,77 @@
+package srtp
+
+import (
+	"encoding/binary"
+	"fmt"
+
+	"github.com/pion/rtcp"
+)
+
+const maxSRTCPIndex = 0x7FFFFFFF
+
+func (c *Context) decryptRTCP(dst, encrypted []byte) ([]byte, error) {
+	out := allocateIfMismatch(dst, encrypted)
+	tailOffset := len(encrypted) - (c.cipher.authTagLen() + srtcpIndexSize)
+
+	if tailOffset < 0 {
+		return nil, fmt.Errorf("%w: %d", errTooShortRTCP, len(encrypted))
+	} else if isEncrypted := encrypted[tailOffset] >> 7; isEncrypted == 0 {
+		return out, nil
+	}
+
+	index := c.cipher.getRTCPIndex(encrypted)
+	ssrc := binary.BigEndian.Uint32(encrypted[4:])
+
+	s := c.getSRTCPSSRCState(ssrc)
+	markAsValid, ok := s.replayDetector.Check(uint64(index))
+	if !ok {
+		return nil, &errorDuplicated{Proto: "srtcp", SSRC: ssrc, Index: index}
+	}
+
+	out, err := c.cipher.decryptRTCP(out, encrypted, index, ssrc)
+	if err != nil {
+		return nil, err
+	}
+
+	markAsValid()
+	return out, nil
+}
+
+// DecryptRTCP decrypts a buffer that contains a RTCP packet
+func (c *Context) DecryptRTCP(dst, encrypted []byte, header *rtcp.Header) ([]byte, error) {
+	if header == nil {
+		header = &rtcp.Header{}
+	}
+
+	if err := header.Unmarshal(encrypted); err != nil {
+		return nil, err
+	}
+
+	return c.decryptRTCP(dst, encrypted)
+}
+
+func (c *Context) encryptRTCP(dst, decrypted []byte) ([]byte, error) {
+	ssrc := binary.BigEndian.Uint32(decrypted[4:])
+	s := c.getSRTCPSSRCState(ssrc)
+
+	// We roll over early because MSB is used for marking as encrypted
+	s.srtcpIndex++
+	if s.srtcpIndex > maxSRTCPIndex {
+		s.srtcpIndex = 0
+	}
+
+	return c.cipher.encryptRTCP(dst, decrypted, s.srtcpIndex, ssrc)
+}
+
+// EncryptRTCP Encrypts a RTCP packet
+func (c *Context) EncryptRTCP(dst, decrypted []byte, header *rtcp.Header) ([]byte, error) {
+	if header == nil {
+		header = &rtcp.Header{}
+	}
+
+	if err := header.Unmarshal(decrypted); err != nil {
+		return nil, err
+	}
+
+	return c.encryptRTCP(dst, decrypted)
+}