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We modified the standard net package to not allocate a *net.UDPAddr during a call to (*net.UDPConn).ReadFromUDP if the caller's use of the *net.UDPAddr does not cause it to escape. That is https://golang.org/cl/291390. This is the companion change to magicsock. There are two changes required. First, call ReadFromUDP instead of ReadFrom, if possible. ReadFrom returns a net.Addr, which is an interface, which always allocates. Second, reduce the lifetime of the returned *net.UDPAddr. We do this by immediately converting it into a netaddr.IPPort. We left the existing RebindingUDPConn.ReadFrom method in place, as it is required to satisfy the net.PacketConn interface. With the upstream change and both of these fixes in place, we have removed one large allocation per packet received. name old time/op new time/op delta ReceiveFrom-8 16.7µs ± 5% 16.4µs ± 8% ~ (p=0.310 n=5+5) name old alloc/op new alloc/op delta ReceiveFrom-8 112B ± 0% 64B ± 0% -42.86% (p=0.008 n=5+5) name old allocs/op new allocs/op delta ReceiveFrom-8 3.00 ± 0% 2.00 ± 0% -33.33% (p=0.008 n=5+5) Co-authored-by: Sonia Appasamy <sonia@tailscale.com> Signed-off-by: Josh Bleecher Snyder <josh@tailscale.com>