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Add ARP packets parsing and socket support
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Original file line number | Diff line number | Diff line change |
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@@ -0,0 +1,69 @@ | ||
package protocols | ||
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import ( | ||
"encoding/binary" | ||
"errors" | ||
"fmt" | ||
"net" | ||
) | ||
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var HardwareTypeValues = map[uint16]string{ | ||
1: "Ethernet", | ||
6: "IEE 802 (Token Ring)", | ||
11: "ATM", | ||
12: "HDLC", | ||
} | ||
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type ARPPacket struct { | ||
EthFrame EthernetFrame | ||
HardwareType uint16 | ||
ProtocolType uint16 | ||
HardwareAddrLen uint8 | ||
ProtocolAddrLen uint8 | ||
Operation uint16 | ||
SenderHWAddr net.HardwareAddr | ||
SenderProtoAddr net.IP // only IPv4 - IPv6 should rely on NDP | ||
TargetHWAddr net.HardwareAddr | ||
TargetProtoAddr net.IP // only IPv4 - IPv6 should rely on NDP | ||
} | ||
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var errInvalidARPPacket = errors.New("ARP packet must be 28 bytes") | ||
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// ARPPacketFromBytes parses an array of bytes to the corresponding ARP packet and returns a pointer to it. | ||
// Returns an error if the number of bytes is less than 28 | ||
func ARPPacketFromBytes(raw []byte) (*ARPPacket, error) { | ||
frame, err := EthFrameFromBytes(raw) | ||
if err != nil { | ||
return nil, err | ||
} | ||
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if len(frame.Payload) < 28 { | ||
return nil, errInvalidARPPacket | ||
} | ||
payload := frame.Payload | ||
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return &ARPPacket{ | ||
EthFrame: *frame, | ||
HardwareType: binary.BigEndian.Uint16(payload[0:2]), | ||
ProtocolType: binary.BigEndian.Uint16(payload[2:4]), | ||
HardwareAddrLen: payload[4], | ||
ProtocolAddrLen: payload[5], | ||
Operation: binary.BigEndian.Uint16(payload[6:8]), | ||
SenderHWAddr: payload[8:14], | ||
SenderProtoAddr: payload[14:18], | ||
TargetHWAddr: payload[18:24], | ||
TargetProtoAddr: payload[24:28], | ||
}, nil | ||
} | ||
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func (p ARPPacket) Destination() string { | ||
return fmt.Sprintf("%s|%s", p.TargetHWAddr.String(), p.TargetProtoAddr.String()) | ||
} | ||
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func (p ARPPacket) Source() string { | ||
return fmt.Sprintf("%s|%s", p.SenderHWAddr.String(), p.SenderProtoAddr.String()) | ||
} | ||
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func (p ARPPacket) Info() string { | ||
return fmt.Sprintf("%s ARP packet from %s to %s", HardwareTypeValues[p.HardwareType], p.Source(), p.Destination()) | ||
} |
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