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Code cleanup

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This commit is contained in:
Kioubit 2021-12-22 06:09:52 -05:00
parent 338139ad0f
commit 7d876fb290
1 changed files with 24 additions and 37 deletions
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35
rawsocket.go
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@ -70,9 +70,16 @@ func listen(iface string, responder chan *NDRequest, requestType NDPType) {
panic(err.Error())
}
var f Filter
var protocolNo uint32
if requestType == NDP_SOL {
f = []bpf.Instruction{
//Neighbor Solicitation
protocolNo = 0x87
} else {
//Neighbor Advertisement
protocolNo = 0x88
}
var f Filter = []bpf.Instruction{
// Load "EtherType" field from the ethernet header.
bpf.LoadAbsolute{Off: 12, Size: 2},
// Jump to the drop packet instruction if EtherType is not IPv6.
@ -83,33 +90,13 @@ func listen(iface string, responder chan *NDRequest, requestType NDPType) {
bpf.JumpIf{Cond: bpf.JumpNotEqual, Val: 0x3a, SkipTrue: 2},
// Load "Type" field from ICMPv6 header.
bpf.LoadAbsolute{Off: 54, Size: 1},
// Jump to the drop packet instruction if Type is not Neighbor Solicitation.
bpf.JumpIf{Cond: bpf.JumpNotEqual, Val: 0x87, SkipTrue: 1},
// Jump to the drop packet instruction if Type is not Neighbor Solicitation / Advertisement.
bpf.JumpIf{Cond: bpf.JumpNotEqual, Val: protocolNo, SkipTrue: 1},
// Verdict is "send up to 4k of the packet to userspace."buf
bpf.RetConstant{Val: 4096},
// Verdict is "ignore packet."
bpf.RetConstant{Val: 0},
}
} else {
f = []bpf.Instruction{
// Load "EtherType" field from the ethernet header.
bpf.LoadAbsolute{Off: 12, Size: 2},
// Jump to the drop packet instruction if EtherType is not IPv6.
bpf.JumpIf{Cond: bpf.JumpNotEqual, Val: 0x86dd, SkipTrue: 4},
// Load "Next Header" field from IPV6 header.
bpf.LoadAbsolute{Off: 20, Size: 1},
// Jump to the drop packet instruction if Next Header is not ICMPv6.
bpf.JumpIf{Cond: bpf.JumpNotEqual, Val: 0x3a, SkipTrue: 2},
// Load "Type" field from ICMPv6 header.
bpf.LoadAbsolute{Off: 54, Size: 1},
// Jump to the drop packet instruction if Type is not Neighbor Advertisement.
bpf.JumpIf{Cond: bpf.JumpNotEqual, Val: 0x88, SkipTrue: 1},
// Verdict is "send up to 4k of the packet to userspace."
bpf.RetConstant{Val: 4096},
// Verdict is "ignore packet."
bpf.RetConstant{Val: 0},
}
}
err = f.ApplyTo(fd)
if err != nil {