net/tsaddr, wgengine/netstack: add IPv6 range that forwards to site-relative IPv4

This defines a new magic IPv6 prefix, fd7a:115c:a1e0:b1a::/64, a
subset of our existing /48, where the final 32 bits are an IPv4
address, and the middle 32 bits are a user-chosen "site ID". (which
must currently be 0000:00xx; the top 3 bytes must be zero for now)

e.g., I can say my home LAN's "site ID" is "0000:00bb" and then
advertise its 10.2.0.0/16 IPv4 range via IPv6, like:

    tailscale up --advertise-routes=fd7a:115c:a1e0:b1a::bb:10.2.0.0/112

(112 being /128 minuse the /96 v6 prefix length)

Then people in my tailnet can:

     $ curl '[fd7a:115c:a1e0:b1a::bb:10.2.0.230]'
     <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" ....

Updates #3616, etc

RELNOTE=initial support for TS IPv6 addresses to route v4 "via" specific nodes

Change-Id: I9b49b6ad10410a24b5866b9fbc69d3cae1f600ef
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
This commit is contained in:
Brad Fitzpatrick
2022-03-30 08:47:16 -07:00
committed by Brad Fitzpatrick
parent f992749b98
commit 3ae701f0eb
6 changed files with 156 additions and 4 deletions

View File

@ -88,3 +88,19 @@ func BenchmarkTailscaleServiceAddr(b *testing.B) {
sinkIP = TailscaleServiceIP()
}
}
func TestUnmapVia(t *testing.T) {
tests := []struct {
ip string
want string
}{
{"1.2.3.4", "1.2.3.4"}, // unchanged v4
{"fd7a:115c:a1e0:b1a::bb:10.2.1.3", "10.2.1.3"},
{"fd7a:115c:a1e0:b1b::bb:10.2.1.4", "fd7a:115c:a1e0:b1b:0:bb:a02:104"}, // "b1b",not "bia"
}
for _, tt := range tests {
if got := UnmapVia(netaddr.MustParseIP(tt.ip)).String(); got != tt.want {
t.Errorf("for %q: got %q, want %q", tt.ip, got, tt.want)
}
}
}