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

@@ -0,0 +1,140 @@
+// SPDX-FileCopyrightText: 2023 The Pion community <https://pion.ly>
+// SPDX-License-Identifier: MIT
+
+package sctp // nolint:dupl
+
+import (
+	"errors"
+	"fmt"
+)
+
+/*
+chunkInitAck represents an SCTP Chunk of type INIT ACK
+
+See chunkInitCommon for the fixed headers
+
+	Variable Parameters                  Status     Type Value
+	-------------------------------------------------------------
+	State Cookie                        Mandatory   7
+	IPv4 IP (Note 1)               		Optional    5
+	IPv6 IP (Note 1)               		Optional    6
+	Unrecognized Parameter              Optional    8
+	Reserved for ECN Capable (Note 2)   Optional    32768 (0x8000)
+	Host Name IP (Note 3)          		Optional    11<Paste>
+*/
+type chunkInitAck struct {
+	chunkHeader
+	chunkInitCommon
+}
+
+// Init ack chunk errors
+var (
+	ErrChunkTypeNotInitAck              = errors.New("ChunkType is not of type INIT ACK")
+	ErrChunkNotLongEnoughForParams      = errors.New("chunk Value isn't long enough for mandatory parameters exp")
+	ErrChunkTypeInitAckFlagZero         = errors.New("ChunkType of type INIT ACK flags must be all 0")
+	ErrInitAckUnmarshalFailed           = errors.New("failed to unmarshal INIT body")
+	ErrInitCommonDataMarshalFailed      = errors.New("failed marshaling INIT common data")
+	ErrChunkTypeInitAckInitateTagZero   = errors.New("ChunkType of type INIT ACK InitiateTag must not be 0")
+	ErrInitAckInboundStreamRequestZero  = errors.New("INIT ACK inbound stream request must be > 0")
+	ErrInitAckOutboundStreamRequestZero = errors.New("INIT ACK outbound stream request must be > 0")
+	ErrInitAckAdvertisedReceiver1500    = errors.New("INIT ACK Advertised Receiver Window Credit (a_rwnd) must be >= 1500")
+)
+
+func (i *chunkInitAck) unmarshal(raw []byte) error {
+	if err := i.chunkHeader.unmarshal(raw); err != nil {
+		return err
+	}
+
+	if i.typ != ctInitAck {
+		return fmt.Errorf("%w: actually is %s", ErrChunkTypeNotInitAck, i.typ.String())
+	} else if len(i.raw) < initChunkMinLength {
+		return fmt.Errorf("%w: %d actual: %d", ErrChunkNotLongEnoughForParams, initChunkMinLength, len(i.raw))
+	}
+
+	// The Chunk Flags field in INIT is reserved, and all bits in it should
+	// be set to 0 by the sender and ignored by the receiver.  The sequence
+	// of parameters within an INIT can be processed in any order.
+	if i.flags != 0 {
+		return ErrChunkTypeInitAckFlagZero
+	}
+
+	if err := i.chunkInitCommon.unmarshal(i.raw); err != nil {
+		return fmt.Errorf("%w: %v", ErrInitAckUnmarshalFailed, err) //nolint:errorlint
+	}
+
+	return nil
+}
+
+func (i *chunkInitAck) marshal() ([]byte, error) {
+	initShared, err := i.chunkInitCommon.marshal()
+	if err != nil {
+		return nil, fmt.Errorf("%w: %v", ErrInitCommonDataMarshalFailed, err) //nolint:errorlint
+	}
+
+	i.chunkHeader.typ = ctInitAck
+	i.chunkHeader.raw = initShared
+	return i.chunkHeader.marshal()
+}
+
+func (i *chunkInitAck) check() (abort bool, err error) {
+	// The receiver of the INIT ACK records the value of the Initiate Tag
+	// parameter.  This value MUST be placed into the Verification Tag
+	// field of every SCTP packet that the INIT ACK receiver transmits
+	// within this association.
+	//
+	// The Initiate Tag MUST NOT take the value 0.  See Section 5.3.1 for
+	// more on the selection of the Initiate Tag value.
+	//
+	// If the value of the Initiate Tag in a received INIT ACK chunk is
+	// found to be 0, the receiver MUST destroy the association
+	// discarding its TCB.  The receiver MAY send an ABORT for debugging
+	// purpose.
+	if i.initiateTag == 0 {
+		abort = true
+		return abort, ErrChunkTypeInitAckInitateTagZero
+	}
+
+	// Defines the maximum number of streams the sender of this INIT ACK
+	// chunk allows the peer end to create in this association.  The
+	// value 0 MUST NOT be used.
+	//
+	// Note: There is no negotiation of the actual number of streams but
+	// instead the two endpoints will use the min(requested, offered).
+	// See Section 5.1.1 for details.
+	//
+	// Note: A receiver of an INIT ACK with the MIS value set to 0 SHOULD
+	// destroy the association discarding its TCB.
+	if i.numInboundStreams == 0 {
+		abort = true
+		return abort, ErrInitAckInboundStreamRequestZero
+	}
+
+	// Defines the number of outbound streams the sender of this INIT ACK
+	// chunk wishes to create in this association.  The value of 0 MUST
+	// NOT be used, and the value MUST NOT be greater than the MIS value
+	// sent in the INIT chunk.
+	//
+	// Note: A receiver of an INIT ACK with the OS value set to 0 SHOULD
+	// destroy the association discarding its TCB.
+
+	if i.numOutboundStreams == 0 {
+		abort = true
+		return abort, ErrInitAckOutboundStreamRequestZero
+	}
+
+	// An SCTP receiver MUST be able to receive a minimum of 1500 bytes in
+	// one SCTP packet.  This means that an SCTP endpoint MUST NOT indicate
+	// less than 1500 bytes in its initial a_rwnd sent in the INIT or INIT
+	// ACK.
+	if i.advertisedReceiverWindowCredit < 1500 {
+		abort = true
+		return abort, ErrInitAckAdvertisedReceiver1500
+	}
+
+	return false, nil
+}
+
+// String makes chunkInitAck printable
+func (i *chunkInitAck) String() string {
+	return fmt.Sprintf("%s\n%s", i.chunkHeader, i.chunkInitCommon)
+}