spath: drop old header code

[lukedirtwalker]

Drops all code supporting the legacy header format. Also since the Path struct
is now that simple it is passed by value instead of pointer.

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This change is 

[matzf]

Reviewed 71 of 71 files at r1.
Reviewable status: all files reviewed, 4 unresolved discussions (waiting on @lukedirtwalker)

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go/cs/beaconing/handler_test.go, line 284 at r1 (raw file):

func testPath(ingressIfid common.IFIDType) spath.Path {
	return spath.Path{}

Is this not needed anymore? It seems to be called with different args in the tests above.

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go/lib/snet/path.go, line 125 at r1 (raw file):

		Raw:  append(p.spath.Raw[:0:0], p.spath.Raw...),
		Type: p.spath.Type,
	}

return p.spath.Copy()

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go/lib/snet/path/path.go, line 63 at r1 (raw file):

		Raw:  append(p.SPath.Raw[:0:0], p.SPath.Raw...),
		Type: p.SPath.Type,
	}

Or just return p.SPath.Copy()?

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go/lib/svc/svc.go, line 208 at r1 (raw file):

		Raw:  append(path.Raw[:0:0], path.Raw...),
		Type: path.Type,
	}

Same here, path = path.Copy()?

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go/pkg/traceroute/traceroute.go, line 294 at r1 (raw file):

			IA:   pkt.Source.IA,
			Host: &net.UDPAddr{IP: pkt.Destination.Host.IP()},
			Path: spath.Path{Raw: append(pkt.Path.Raw[:0:0], pkt.Path.Raw...), Type: pkt.Path.Type},

Path: pkt.Path.Copy()

[lukedirtwalker]

Reviewable status: all files reviewed, 4 unresolved discussions (waiting on @matzf)

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go/cs/beaconing/handler_test.go, line 284 at r1 (raw file):

Previously, matzf (Matthias Frei) wrote…

Is this not needed anymore? It seems to be called with different args in the tests above.

No, I removed it. In v1 we checked something on the path, which we no longer do in v2.

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go/lib/snet/path.go, line 125 at r1 (raw file):

Previously, matzf (Matthias Frei) wrote…

return p.spath.Copy()

Done.

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go/lib/snet/path/path.go, line 63 at r1 (raw file):

Previously, matzf (Matthias Frei) wrote…

Or just return p.SPath.Copy()?

Done.

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go/lib/svc/svc.go, line 208 at r1 (raw file):

Previously, matzf (Matthias Frei) wrote…

Same here, path = path.Copy()?

Done.

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go/pkg/traceroute/traceroute.go, line 294 at r1 (raw file):

Previously, matzf (Matthias Frei) wrote…

Path: pkt.Path.Copy()

Done.

[matzf]

Reviewed 5 of 5 files at r2.
Reviewable status: complete! all files reviewed, all discussions resolved

[lukedirtwalker]

Reviewed 66 of 71 files at r1, 5 of 5 files at r2.
Reviewable status: complete! all files reviewed, all discussions resolved