types.go

package nflog

import (
	"errors"
	"time"
)

// Various constants
const (
	// Available copy modes for Config.Copymode.
	CopyNone byte = 0x00
	CopyMeta byte = 0x01
	// Provides a complete copy of the packet in the Msg map.
	// But can be limited by setting Config.Bufsize.
	CopyPacket byte = 0x02

	// Flags that can be set on a connection
	FlagSeq    uint16 = 0x0001
	FlagGlobal uint16 = 0x0002
	// Requires Kernel configuration of CONFIG_NETFILTER_NETLINK_GLUE_CT
	FlagConntrack uint16 = 0x0004
)

// Various optional settings
const (
	GenericGroup uint16 = 0x1
)

// Various errors
var (
	ErrCopyMode    = errors.New("unsupported copy mode")
	ErrUnknownFlag = errors.New("unsupported flag")
)

// nfLogSubSysUlog the netlink subsystem we will query
const nfnlSubSysUlog = 0x04

// Message types from nfulnl_msg_types
const (
	// Userspace to kernel
	nfUlnlMsgConfig = 1
)

const (
	_ = iota
	nfUlACfgCmd
	nfUlACfgMode
	nfUlACfgNlBufSize
	nfUlACfgTimeOut /* in 1/100 s */
	nfUlACfgQThresh
	nfUlACfgFlags
)

const (
	_ = iota
	nfUlnlCfgCmdBind
	nfUlnlCfgCmdUnbind
	nfUlnlCfgCmdPfBind
	nfUlnlCfgCmdPfUnbind
)

const (
	_ = iota
	nfUlaAttrPacketHdr
	nfUlaAttrMark
	nfUlaAttrTimestamp
	nfUlaAttrIfindexIndev
	nfUlaAttrIfindexOutdev
	nfUlaAttrIfindexPhysIndev
	nfUlaAttrIfindexPhysOutdev
	nfUlaAttrHwaddr
	nfUlaAttrPayload
	nfUlaAttrPrefix
	nfUlaAttrUID
	nfUlaAttrSeq
	nfUlaAttrSeqGlobal
	nfUlaAttrGID
	nfUlaAttrHwType
	nfUlaAttrHwHeader
	nfUlaAttrHwLen
	nfUlaAttrCt
	nfUlaAttrCtInfo
	nfUlaAttrVlan
	nfulaAttrL2Hdr
)

// Attribute contains various elements for nflog elements.
// As not every value is contained in every nflog message,
// the elements inside Attribute are pointers to these values
// or nil, if not present.
type Attribute struct {
	Hook       *uint8
	Mark       *uint32
	Timestamp  *time.Time
	InDev      *uint32
	PhysInDev  *uint32
	OutDev     *uint32
	PhysOutDev *uint32
	Payload    *[]byte
	Prefix     *string
	UID        *uint32
	Seq        *uint32
	SeqGlobal  *uint32
	GID        *uint32
	HwType     *uint16
	HwAddr     *[]byte
	HwHeader   *[]byte
	HwLen      *uint16
	HwProtocol *uint16
	CtInfo     *uint32
	Ct         *[]byte
	Layer2Hdr  *[]byte
	VLAN       *VLAN
}

// VLAN holds the VLAN information.
type VLAN struct {
	Proto uint16
	TCI   uint16
}

// Logger provides logging functionality.
type Logger interface {
	Debugf(format string, args ...interface{})
	Errorf(format string, args ...interface{})
}

// Config contains options for a Conn.
type Config struct {
	// Network namespace the Nflog needs to operate in. If set to 0 (default),
	// no network namespace will be entered.
	NetNS int

	// Optional flags for the nflog communication
	Flags uint16

	// Specifies the number of packets in the group,
	// until they will be pushed to userspace.
	QThresh uint32

	// Maximum time in 1/100s that a packet in the nflog group will be queued,
	// until it is pushed to userspace.
	Timeout uint32

	// Nflog group this socket will be assigned to.
	Group uint16

	// Specifies how the kernel handles a packet in the nflog group.
	Copymode uint8

	// If NfUlnlCopyPacket is set as CopyMode,
	// this parameter specifies the maximum number of bytes,
	// that will be copied to userspace.
	Bufsize uint32

	// Optional settings to enable/disable features
	Settings uint16

	// Time till a read action times out - only available for Go >= 1.12
	//
	// Deprecated: Cancel the context passed to RegisterWithErrorFunc() or Register()
	// to remove the hook from the nfloq gracefully. Setting this value does no longer
	// have an effect on nflog.
	ReadTimeout time.Duration

	// Interface to log internals.
	Logger Logger
}

// ErrorFunc is a function that receives all errors that happen while reading
// from a Netlinkgroup. To stop receiving messages return something different than 0.
type ErrorFunc func(e error) int

// HookFunc is a function, that receives events from a Netlinkgroup
// To stop receiving messages on this HookFunc, return something different than 0
type HookFunc func(a Attribute) int