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// Copyright 2018 The gVisor Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package header
import (
"gvisor.dev/gvisor/pkg/tcpip"
)
const (
// MaxIPPacketSize is the maximum supported IP packet size, excluding
// jumbograms. The maximum IPv4 packet size is 64k-1 (total size must fit
// in 16 bits). For IPv6, the payload max size (excluding jumbograms) is
// 64k-1 (also needs to fit in 16 bits). So we use 64k - 1 + 2 * m, where
// m is the minimum IPv6 header size; we leave room for some potential
// IP options.
MaxIPPacketSize = 0xffff + 2*IPv6MinimumSize
)
// Transport offers generic methods to query and/or update the fields of the
// header of a transport protocol buffer.
type Transport interface {
// SourcePort returns the value of the "source port" field.
SourcePort() uint16
// Destination returns the value of the "destination port" field.
DestinationPort() uint16
// Checksum returns the value of the "checksum" field.
Checksum() uint16
// SetSourcePort sets the value of the "source port" field.
SetSourcePort(uint16)
// SetDestinationPort sets the value of the "destination port" field.
SetDestinationPort(uint16)
// SetChecksum sets the value of the "checksum" field.
SetChecksum(uint16)
// Payload returns the data carried in the transport buffer.
Payload() []byte
}
// ChecksummableTransport is a Transport that supports checksumming.
type ChecksummableTransport interface {
Transport
// SetSourcePortWithChecksumUpdate sets the source port and updates
// the checksum.
//
// The receiver's checksum must be a fully calculated checksum.
SetSourcePortWithChecksumUpdate(port uint16)
// SetDestinationPortWithChecksumUpdate sets the destination port and updates
// the checksum.
//
// The receiver's checksum must be a fully calculated checksum.
SetDestinationPortWithChecksumUpdate(port uint16)
// UpdateChecksumPseudoHeaderAddress updates the checksum to reflect an
// updated address in the pseudo header.
//
// If fullChecksum is true, the receiver's checksum field is assumed to hold a
// fully calculated checksum. Otherwise, it is assumed to hold a partially
// calculated checksum which only reflects the pseudo header.
UpdateChecksumPseudoHeaderAddress(old, new tcpip.Address, fullChecksum bool)
}
// Network offers generic methods to query and/or update the fields of the
// header of a network protocol buffer.
type Network interface {
// SourceAddress returns the value of the "source address" field.
SourceAddress() tcpip.Address
// DestinationAddress returns the value of the "destination address"
// field.
DestinationAddress() tcpip.Address
// Checksum returns the value of the "checksum" field.
Checksum() uint16
// SetSourceAddress sets the value of the "source address" field.
SetSourceAddress(tcpip.Address)
// SetDestinationAddress sets the value of the "destination address"
// field.
SetDestinationAddress(tcpip.Address)
// SetChecksum sets the value of the "checksum" field.
SetChecksum(uint16)
// TransportProtocol returns the number of the transport protocol
// stored in the payload.
TransportProtocol() tcpip.TransportProtocolNumber
// Payload returns a byte slice containing the payload of the network
// packet.
Payload() []byte
// TOS returns the values of the "type of service" and "flow label" fields.
TOS() (uint8, uint32)
// SetTOS sets the values of the "type of service" and "flow label" fields.
SetTOS(t uint8, l uint32)
}
// ChecksummableNetwork is a Network that supports checksumming.
type ChecksummableNetwork interface {
Network
// SetSourceAddressAndChecksum sets the source address and updates the
// checksum to reflect the new address.
SetSourceAddressWithChecksumUpdate(tcpip.Address)
// SetDestinationAddressAndChecksum sets the destination address and
// updates the checksum to reflect the new address.
SetDestinationAddressWithChecksumUpdate(tcpip.Address)
}
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