Class: Mu::Pcap::Ethernet

Inherits:
Packet
  • Object
show all
Defined in:
lib/diy/parser/mu/pcap/ethernet.rb

Constant Summary collapse

ETHERTYPE_IP = 
0x0800
ETHERTYPE_IP6 = 
0x86dd
ETHERTYPE_ARP = 
0x0806
ETHERTYPE_PPPOE_SESSION = 
0x8864
ETHERTYPE_802_1Q = 
0X8100
PPP_IP = 
0x0021
PPP_IPV6 = 
0x0057
FMT_MAC = 
"C6"
FMT_n = 
'n'
MAC_TEMPLATE = 
'%02x:%02x:%02x:%02x:%02x:%02x'
ADDR_TO_BYTES = 
{}
FMT_HEADER = 
'a6a6n'

Constants inherited from Packet

Packet::IGNORE_UDP_PORTS

Instance Attribute Summary collapse

Attributes inherited from Packet

#payload, #payload_raw

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from Packet

#deepdup, isolate_l7, normalize, #payload_bytes, #to_bytes

Constructor Details

#initialize(src = nil, dst = nil, type = 0) ⇒ Ethernet

Returns a new instance of Ethernet.



20
21
22
23
24
25
 
# File 'lib/diy/parser/mu/pcap/ethernet.rb', line 20

def initialize src=nil, dst=nil, type=0
    super()
    @src = src
    @dst = dst
    @type = type
end

Instance Attribute Details

#dst ⇒ Object

Returns the value of attribute dst.



9
10
11
 
# File 'lib/diy/parser/mu/pcap/ethernet.rb', line 9

def dst
  @dst
end

#src ⇒ Object

Returns the value of attribute src.



9
10
11
 
# File 'lib/diy/parser/mu/pcap/ethernet.rb', line 9

def src
  @src
end

#type ⇒ Object

Returns the value of attribute type.



9
10
11
 
# File 'lib/diy/parser/mu/pcap/ethernet.rb', line 9

def type
  @type
end

Class Method Details

.from_bytes(bytes) ⇒ Object 



38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
 
# File 'lib/diy/parser/mu/pcap/ethernet.rb', line 38

def self.from_bytes bytes
    if bytes.length < 14
        raise ParseError, "Truncated Ethernet header: expected 14 bytes, got #{bytes.length} bytes"
    end

    dst = bytes.slice!(0,6).unpack FMT_MAC
    dst = MAC_TEMPLATE % dst
    src = bytes.slice!(0,6).unpack FMT_MAC
    src = MAC_TEMPLATE % src
    type = bytes.slice!(0,2).unpack(FMT_n)[0]
    while (type == ETHERTYPE_802_1Q)
        # Skip 4 bytes for 802.1q vlan tag field
        bytes.slice!(0,2)
        type = bytes.slice!(0,2).unpack(FMT_n)[0]
    end
    ethernet = Ethernet.new src, dst, type
    ethernet.payload = bytes
    ethernet.payload_raw = bytes
    begin
        case type
        when ETHERTYPE_IP
            ethernet.payload = IPv4.from_bytes bytes
        when ETHERTYPE_IP6
            ethernet.payload = IPv6.from_bytes bytes
        when ETHERTYPE_PPPOE_SESSION
            # Remove PPPoE/PPP session layer
            ethernet.payload = bytes
            ethernet.remove_pppoe!
        else
            ethernet.payload = bytes
        end
    rescue ParseError => e
        Pcap.warning e
    end
    return ethernet
end

Instance Method Details

#==(other) ⇒ Object 



139
140
141
142
143
144
 
# File 'lib/diy/parser/mu/pcap/ethernet.rb', line 139

def == other
    return super &&
        self.src  == other.src &&
        self.dst  == other.dst &&
        self.type == other.type
end

#flow_id ⇒ Object 



27
28
29
30
31
32
33
 
# File 'lib/diy/parser/mu/pcap/ethernet.rb', line 27

def flow_id
    if not @payload or @payload.is_a? String
        return [:ethernet, @src, @dst, @type]
    else
        return @payload.flow_id
    end
end

#ip? ⇒ Boolean

Returns:

  • (Boolean) 


75
76
77
 
# File 'lib/diy/parser/mu/pcap/ethernet.rb', line 75

def ip?
    return payload.is_a?(IP)
end

#remove_pppoe! ⇒ Object

Remove the PPPoE and PPP headers. PPPoE is documented in RFC 2516.



94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
 
# File 'lib/diy/parser/mu/pcap/ethernet.rb', line 94

def remove_pppoe!
    bytes = self.payload_raw

    # Remove PPPoE header
    Pcap.assert bytes.length >= 6, 'Truncated PPPoE header: ' +
        "expected at least 6 bytes, got #{bytes.length} bytes"
    version_type, code, session_id, length = bytes.unpack 'CCnn'
    version = version_type >> 4 & 0b1111
    type    = version_type      & 0b1111
    Pcap.assert version == 1, "Unknown PPPoE version: #{version}"
    Pcap.assert type == 1, "Unknown PPPoE type: #{type}"
    Pcap.assert code == 0, "Unknown PPPoE code: #{code}"
    bytes = bytes[6..-1]
    Pcap.assert bytes.length >= length, 'Truncated PPoE packet: ' +
        "expected #{length} bytes, got #{bytes.length} bytes"
    
    # Remove PPP header
    Pcap.assert bytes.length >= 2, 'Truncated PPP packet: ' +
        "expected at least bytes, got #{bytes.length} bytes"
    protocol_id, = bytes.unpack 'n'
    bytes = bytes[2..-1]
    case protocol_id
    when PPP_IP
        self.payload = IPv4.from_bytes bytes
        self.payload_raw = bytes
        self.type = ETHERTYPE_IP
    when PPP_IPV6
        self.payload = IPv6.from_bytes bytes
        self.payload_raw = bytes
        self.type = ETHERTYPE_IP6
    else
        # Failed.  Don't update payload or type.
        raise ParseError, "Unknown PPP protocol: 0x#{'%04x' % protocol_id}"
    end
end

#to_s ⇒ Object 



130
131
132
133
134
135
136
137
 
# File 'lib/diy/parser/mu/pcap/ethernet.rb', line 130

def to_s
    if @payload.is_a? String
        payload = @payload.inspect
    else
        payload = @payload.to_s
    end
    return "ethernet(%s, %s, %d, %s)" % [@src, @dst, @type, payload]
end

#write(io) ⇒ Object 



81
82
83
84
85
86
87
88
89
90
91
 
# File 'lib/diy/parser/mu/pcap/ethernet.rb', line 81

def write io
    dst_mac = ADDR_TO_BYTES[@dst] ||= @dst.split(':').inject('') {|m, b| m << b.to_i(16).chr}
    src_mac = ADDR_TO_BYTES[@src] ||= @src.split(':').inject('') {|m, b| m << b.to_i(16).chr}
    bytes = [dst_mac, src_mac, @type].pack(FMT_HEADER)
    io.write bytes
    if @payload.is_a? String
        io.write @payload
    else
        @payload.write io
    end
end