| Matteo Scandolo | a6a3aee | 2019-11-26 13:30:14 -0700 | [diff] [blame] | 1 | // Copyright 2012 Google, Inc. All rights reserved. |
| 2 | // |
| 3 | // Use of this source code is governed by a BSD-style license |
| 4 | // that can be found in the LICENSE file in the root of the source |
| 5 | // tree. |
| 6 | |
| 7 | package layers |
| 8 | |
| 9 | import ( |
| 10 | "encoding/binary" |
| 11 | "errors" |
| 12 | |
| 13 | "github.com/google/gopacket" |
| 14 | ) |
| 15 | |
| 16 | type PFDirection uint8 |
| 17 | |
| 18 | const ( |
| 19 | PFDirectionInOut PFDirection = 0 |
| 20 | PFDirectionIn PFDirection = 1 |
| 21 | PFDirectionOut PFDirection = 2 |
| 22 | ) |
| 23 | |
| 24 | // PFLog provides the layer for 'pf' packet-filter logging, as described at |
| 25 | // http://www.freebsd.org/cgi/man.cgi?query=pflog&sektion=4 |
| 26 | type PFLog struct { |
| 27 | BaseLayer |
| 28 | Length uint8 |
| 29 | Family ProtocolFamily |
| 30 | Action, Reason uint8 |
| 31 | IFName, Ruleset []byte |
| 32 | RuleNum, SubruleNum uint32 |
| 33 | UID uint32 |
| 34 | PID int32 |
| 35 | RuleUID uint32 |
| 36 | RulePID int32 |
| 37 | Direction PFDirection |
| 38 | // The remainder is padding |
| 39 | } |
| 40 | |
| 41 | func (pf *PFLog) DecodeFromBytes(data []byte, df gopacket.DecodeFeedback) error { |
| 42 | pf.Length = data[0] |
| 43 | pf.Family = ProtocolFamily(data[1]) |
| 44 | pf.Action = data[2] |
| 45 | pf.Reason = data[3] |
| 46 | pf.IFName = data[4:20] |
| 47 | pf.Ruleset = data[20:36] |
| 48 | pf.RuleNum = binary.BigEndian.Uint32(data[36:40]) |
| 49 | pf.SubruleNum = binary.BigEndian.Uint32(data[40:44]) |
| 50 | pf.UID = binary.BigEndian.Uint32(data[44:48]) |
| 51 | pf.PID = int32(binary.BigEndian.Uint32(data[48:52])) |
| 52 | pf.RuleUID = binary.BigEndian.Uint32(data[52:56]) |
| 53 | pf.RulePID = int32(binary.BigEndian.Uint32(data[56:60])) |
| 54 | pf.Direction = PFDirection(data[60]) |
| 55 | if pf.Length%4 != 1 { |
| 56 | return errors.New("PFLog header length should be 3 less than multiple of 4") |
| 57 | } |
| 58 | actualLength := int(pf.Length) + 3 |
| 59 | pf.Contents = data[:actualLength] |
| 60 | pf.Payload = data[actualLength:] |
| 61 | return nil |
| 62 | } |
| 63 | |
| 64 | // LayerType returns layers.LayerTypePFLog |
| 65 | func (pf *PFLog) LayerType() gopacket.LayerType { return LayerTypePFLog } |
| 66 | |
| 67 | func (pf *PFLog) CanDecode() gopacket.LayerClass { return LayerTypePFLog } |
| 68 | |
| 69 | func (pf *PFLog) NextLayerType() gopacket.LayerType { |
| 70 | return pf.Family.LayerType() |
| 71 | } |
| 72 | |
| 73 | func decodePFLog(data []byte, p gopacket.PacketBuilder) error { |
| 74 | pf := &PFLog{} |
| 75 | return decodingLayerDecoder(pf, data, p) |
| 76 | } |