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server/vendor/github.com/pion/sctp/paramheader.go

@@ -0,0 +1,101 @@
+// SPDX-FileCopyrightText: 2023 The Pion community <https://pion.ly>
+// SPDX-License-Identifier: MIT
+
+package sctp
+
+import (
+	"encoding/binary"
+	"encoding/hex"
+	"errors"
+	"fmt"
+)
+
+type paramHeaderUnrecognizedAction byte
+
+type paramHeader struct {
+	typ                paramType
+	unrecognizedAction paramHeaderUnrecognizedAction
+	len                int
+	raw                []byte
+}
+
+/*
+	 The Parameter Types are encoded such that the highest-order 2 bits specify
+	 the action that is taken if the processing endpoint does not recognize the
+	 Parameter Type.
+
+	 00 - Stop processing this parameter and do not process any further parameters within this chunk.
+
+	 01 - Stop processing this parameter, do not process any further parameters within this chunk, and
+		  report the unrecognized parameter, as described in Section 3.2.2.
+
+	 10 - Skip this parameter and continue processing.
+
+	 11 - Skip this parameter and continue processing, but report the unrecognized
+		  parameter, as described in Section 3.2.2.
+
+	 https://www.rfc-editor.org/rfc/rfc9260.html#section-3.2.1
+*/
+
+const (
+	paramHeaderUnrecognizedActionMask                                        = 0b11000000
+	paramHeaderUnrecognizedActionStop          paramHeaderUnrecognizedAction = 0b00000000
+	paramHeaderUnrecognizedActionStopAndReport paramHeaderUnrecognizedAction = 0b01000000
+	paramHeaderUnrecognizedActionSkip          paramHeaderUnrecognizedAction = 0b10000000
+	paramHeaderUnrecognizedActionSkipAndReport paramHeaderUnrecognizedAction = 0b11000000
+
+	paramHeaderLength = 4
+)
+
+// Parameter header parse errors
+var (
+	ErrParamHeaderTooShort                  = errors.New("param header too short")
+	ErrParamHeaderSelfReportedLengthShorter = errors.New("param self reported length is shorter than header length")
+	ErrParamHeaderSelfReportedLengthLonger  = errors.New("param self reported length is longer than header length")
+	ErrParamHeaderParseFailed               = errors.New("failed to parse param type")
+)
+
+func (p *paramHeader) marshal() ([]byte, error) {
+	paramLengthPlusHeader := paramHeaderLength + len(p.raw)
+
+	rawParam := make([]byte, paramLengthPlusHeader)
+	binary.BigEndian.PutUint16(rawParam[0:], uint16(p.typ))
+	binary.BigEndian.PutUint16(rawParam[2:], uint16(paramLengthPlusHeader))
+	copy(rawParam[paramHeaderLength:], p.raw)
+
+	return rawParam, nil
+}
+
+func (p *paramHeader) unmarshal(raw []byte) error {
+	if len(raw) < paramHeaderLength {
+		return ErrParamHeaderTooShort
+	}
+
+	paramLengthPlusHeader := binary.BigEndian.Uint16(raw[2:])
+	if int(paramLengthPlusHeader) < paramHeaderLength {
+		return fmt.Errorf("%w: param self reported length (%d) shorter than header length (%d)", ErrParamHeaderSelfReportedLengthShorter, int(paramLengthPlusHeader), paramHeaderLength)
+	}
+	if len(raw) < int(paramLengthPlusHeader) {
+		return fmt.Errorf("%w: param length (%d) shorter than its self reported length (%d)", ErrParamHeaderSelfReportedLengthLonger, len(raw), int(paramLengthPlusHeader))
+	}
+
+	typ, err := parseParamType(raw[0:])
+	if err != nil {
+		return fmt.Errorf("%w: %v", ErrParamHeaderParseFailed, err) //nolint:errorlint
+	}
+	p.typ = typ
+	p.unrecognizedAction = paramHeaderUnrecognizedAction(raw[0] & paramHeaderUnrecognizedActionMask)
+	p.raw = raw[paramHeaderLength:paramLengthPlusHeader]
+	p.len = int(paramLengthPlusHeader)
+
+	return nil
+}
+
+func (p *paramHeader) length() int {
+	return p.len
+}
+
+// String makes paramHeader printable
+func (p paramHeader) String() string {
+	return fmt.Sprintf("%s (%d): %s", p.typ, p.len, hex.Dump(p.raw))
+}