85 lines
2.3 KiB
Go
85 lines
2.3 KiB
Go
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// Copyright 2012 Google, Inc. All rights reserved.
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//
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// Use of this source code is governed by a BSD-style license
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// that can be found in the LICENSE file in the root of the source
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// tree.
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package layers
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import (
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"encoding/binary"
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"errors"
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"fmt"
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"github.com/google/gopacket"
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)
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type PFDirection uint8
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const (
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PFDirectionInOut PFDirection = 0
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PFDirectionIn PFDirection = 1
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PFDirectionOut PFDirection = 2
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)
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// PFLog provides the layer for 'pf' packet-filter logging, as described at
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// http://www.freebsd.org/cgi/man.cgi?query=pflog&sektion=4
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type PFLog struct {
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BaseLayer
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Length uint8
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Family ProtocolFamily
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Action, Reason uint8
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IFName, Ruleset []byte
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RuleNum, SubruleNum uint32
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UID uint32
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PID int32
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RuleUID uint32
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RulePID int32
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Direction PFDirection
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// The remainder is padding
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}
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func (pf *PFLog) DecodeFromBytes(data []byte, df gopacket.DecodeFeedback) error {
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if len(data) < 60 {
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df.SetTruncated()
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return errors.New("PFLog data less than 60 bytes")
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}
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pf.Length = data[0]
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pf.Family = ProtocolFamily(data[1])
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pf.Action = data[2]
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pf.Reason = data[3]
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pf.IFName = data[4:20]
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pf.Ruleset = data[20:36]
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pf.RuleNum = binary.BigEndian.Uint32(data[36:40])
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pf.SubruleNum = binary.BigEndian.Uint32(data[40:44])
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pf.UID = binary.BigEndian.Uint32(data[44:48])
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pf.PID = int32(binary.BigEndian.Uint32(data[48:52]))
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pf.RuleUID = binary.BigEndian.Uint32(data[52:56])
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pf.RulePID = int32(binary.BigEndian.Uint32(data[56:60]))
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pf.Direction = PFDirection(data[60])
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if pf.Length%4 != 1 {
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return errors.New("PFLog header length should be 3 less than multiple of 4")
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}
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actualLength := int(pf.Length) + 3
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if len(data) < actualLength {
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return fmt.Errorf("PFLog data size < %d", actualLength)
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}
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pf.Contents = data[:actualLength]
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pf.Payload = data[actualLength:]
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return nil
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}
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// LayerType returns layers.LayerTypePFLog
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func (pf *PFLog) LayerType() gopacket.LayerType { return LayerTypePFLog }
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func (pf *PFLog) CanDecode() gopacket.LayerClass { return LayerTypePFLog }
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func (pf *PFLog) NextLayerType() gopacket.LayerType {
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return pf.Family.LayerType()
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}
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func decodePFLog(data []byte, p gopacket.PacketBuilder) error {
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pf := &PFLog{}
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return decodingLayerDecoder(pf, data, p)
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}
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