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127 lines
4.9 KiB
Go
127 lines
4.9 KiB
Go
package sctp
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import "github.com/pkg/errors"
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// Init represents an SCTP Chunk of type INIT
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//
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// 0 1 2 3
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// 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
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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// | Type = 1 | Chunk Flags | Chunk Length |
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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// | Initiate Tag |
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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// | Advertised Receiver Window Credit (a_rwnd) |
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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// | Number of Outbound Streams | Number of Inbound Streams |
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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// | Initial TSN |
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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// | |
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// | Optional/Variable-Length Parameters |
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// | |
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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//
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// The INIT chunk contains the following parameters. Unless otherwise
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// noted, each parameter MUST only be included once in the INIT chunk.
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//
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// Fixed Parameters Status
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// ----------------------------------------------
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// Initiate Tag Mandatory
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// Advertised Receiver Window Credit Mandatory
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// Number of Outbound Streams Mandatory
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// Number of Inbound Streams Mandatory
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// Initial TSN Mandatory
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//
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// Variable Parameters Status Type Value
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// -------------------------------------------------------------
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// IPv4 Address (Note 1) Optional 5
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// IPv6 Address (Note 1) Optional 6
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// Cookie Preservative Optional 9
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// Reserved for ECN Capable (Note 2) Optional 32768 (0x8000)
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// Host Name Address (Note 3) Optional 11
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// Supported Address Types (Note 4) Optional 12
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type Init struct {
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ChunkHeader
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InitCommon
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}
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// Unmarshal populates a Init Chunk from a byte slice
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func (i *Init) Unmarshal(raw []byte) error {
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if err := i.unmarshalHeader(raw); err != nil {
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return err
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}
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if i.typ != INIT {
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return errors.Errorf("ChunkType is not of type INIT, actually is %s", i.typ.String())
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} else if len(i.Value) < initChunkMinLength {
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return errors.Errorf("Chunk Value isn't long enough for mandatory parameters exp: %d actual: %d", initChunkMinLength, len(i.Value))
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}
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// The Chunk Flags field in INIT is reserved, and all bits in it should
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// be set to 0 by the sender and ignored by the receiver. The sequence
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// of parameters within an INIT can be processed in any order.
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if i.Flags != 0 {
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return errors.New("ChunkType of type INIT flags must be all 0")
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}
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if err := i.InitCommon.Unmarshal(i.Value); err != nil {
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errors.Wrap(err, "Failed to unmarshal INIT body")
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}
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return nil
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}
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// Marshal generates raw data from a Init struct
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func (i *Init) Marshal() ([]byte, error) {
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return nil, errors.Errorf("Unimplemented")
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}
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// Check asserts the validity of this structs values
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func (i *Init) Check() (abort bool, err error) {
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// The receiver of the INIT (the responding end) records the value of
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// the Initiate Tag parameter. This value MUST be placed into the
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// Verification Tag field of every SCTP packet that the receiver of
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// the INIT transmits within this association.
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//
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// The Initiate Tag is allowed to have any value except 0. See
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// Section 5.3.1 for more on the selection of the tag value.
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//
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// If the value of the Initiate Tag in a received INIT chunk is found
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// to be 0, the receiver MUST treat it as an error and close the
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// association by transmitting an ABORT.
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if i.initiateTag == 0 {
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abort = true
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return abort, errors.New("ChunkType of type INIT ACK InitiateTag must not be 0")
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}
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// Defines the maximum number of streams the sender of this INIT
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// chunk allows the peer end to create in this association. The
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// value 0 MUST NOT be used.
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//
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// Note: There is no negotiation of the actual number of streams but
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// instead the two endpoints will use the min(requested, offered).
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// See Section 5.1.1 for details.
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//
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// Note: A receiver of an INIT with the MIS value of 0 SHOULD abort
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// the association.
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if i.numInboundStreams == 0 {
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abort = true
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return abort, errors.New("INIT inbound stream request must be > 0")
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}
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// Defines the number of outbound streams the sender of this INIT
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// chunk wishes to create in this association. The value of 0 MUST
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// NOT be used.
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//
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// Note: A receiver of an INIT with the OS value set to 0 SHOULD
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// abort the association.
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if i.numOutboundStreams == 0 {
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abort = true
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return abort, errors.New("INIT outbound stream request must be > 0")
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}
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return false, nil
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}
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