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bebfa254cf
Change-Id: I4f01343911102f5acf16ca6d5eb39ec98a5f2478 Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
53 lines
1.8 KiB
Go
53 lines
1.8 KiB
Go
package main
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import (
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"net/netip"
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"time"
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)
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// NATTable is what a NAT implementation is expected to do.
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//
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// This project tests Tailscale as it faces various combinations various NAT
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// implementations (e.g. Linux easy style NAT vs FreeBSD hard/endpoint dependent
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// NAT vs Cloud 1:1 NAT, etc)
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//
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// Implementations of NATTable need not handle concurrency; the natlab serializes
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// all calls into a NATTable.
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//
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// The provided `at` value will typically be time.Now, except for tests.
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// Implementations should not use real time and should only compare
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// previously provided time values.
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type NATTable interface {
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// PickOutgoingSrc returns the source address to use for an outgoing packet.
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//
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// The result should either be invalid (to drop the packet) or a WAN (not
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// private) IP address.
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//
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// Typically, the src is a LAN source IP address, but it might also be a WAN
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// IP address if the packet is being forwarded for a source machine that has
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// a public IP address.
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PickOutgoingSrc(src, dst netip.AddrPort, at time.Time) (wanSrc netip.AddrPort)
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// PickIncomingDst returns the destination address to use for an incoming
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// packet. The incoming src address is always a public WAN IP.
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//
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// The result should either be invalid (to drop the packet) or the IP
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// address of a machine on the local network address, usually a private
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// LAN IP.
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PickIncomingDst(src, dst netip.AddrPort, at time.Time) (lanDst netip.AddrPort)
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}
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// oneToOneNAT is a 1:1 NAT, like a typical EC2 VM.
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type oneToOneNAT struct {
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lanIP netip.Addr
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wanIP netip.Addr
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}
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func (n *oneToOneNAT) PickOutgoingSrc(src, dst netip.AddrPort, at time.Time) (wanSrc netip.AddrPort) {
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return netip.AddrPortFrom(n.wanIP, src.Port())
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}
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func (n *oneToOneNAT) PickIncomingDst(src, dst netip.AddrPort, at time.Time) (lanDst netip.AddrPort) {
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return netip.AddrPortFrom(n.lanIP, dst.Port())
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}
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