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wgengine/magicsock: remove final alloc from ReceiveFrom

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And now that we don't have to play escape analysis and inlining games,
simplify the code.

Signed-off-by: Josh Bleecher Snyder <josh@tailscale.com>
This commit is contained in:
Josh Bleecher Snyder
2022-03-15 15:33:06 -07:00
committed by Josh Bleecher Snyder
parent 463728a885
commit 1b57b0380d
3 changed files with 25 additions and 23 deletions
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35
wgengine/magicsock/magicsock.go
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@@ -17,6 +17,7 @@ import (
"math"
"math/rand"
"net"
"net/netip"
"reflect"
"runtime"
"sort"
@@ -53,6 +54,7 @@ import (
"tailscale.com/types/netmap"
"tailscale.com/types/nettype"
"tailscale.com/util/clientmetric"
"tailscale.com/util/netconv"
"tailscale.com/util/uniq"
"tailscale.com/version"
"tailscale.com/wgengine/monitor"
@@ -3025,35 +3027,30 @@ func (c *RebindingUDPConn) ReadFromNetaddr(b []byte) (n int, ipp netaddr.IPPort,
pconn := c.currentConn()
// Optimization: Treat *net.UDPConn specially.
// ReadFromUDP gets partially inlined, avoiding allocating a *net.UDPAddr,
// as long as pAddr itself doesn't escape.
// This lets us avoid allocations by calling ReadFromUDPAddrPort.
// The non-*net.UDPConn case works, but it allocates.
var pAddr *net.UDPAddr
if udpConn, ok := pconn.(*net.UDPConn); ok {
n, pAddr, err = udpConn.ReadFromUDP(b)
var ap netip.AddrPort
n, ap, err = udpConn.ReadFromUDPAddrPort(b)
ipp = netconv.AsIPPort(ap)
} else {
var addr net.Addr
n, addr, err = pconn.ReadFrom(b)
if addr != nil {
pAddr, ok = addr.(*net.UDPAddr)
pAddr, ok := addr.(*net.UDPAddr)
if addr != nil && !ok {
return 0, netaddr.IPPort{}, fmt.Errorf("RebindingUDPConn.ReadFromNetaddr: underlying connection returned address of type %T, want *netaddr.UDPAddr", addr)
}
if pAddr != nil {
ipp, ok = netaddr.FromStdAddr(pAddr.IP, pAddr.Port, pAddr.Zone)
if !ok {
return 0, netaddr.IPPort{}, fmt.Errorf("RebindingUDPConn.ReadFromNetaddr: underlying connection returned address of type %T, want *netaddr.UDPAddr", addr)
return 0, netaddr.IPPort{}, errors.New("netaddr.FromStdAddr failed")
}
}
}
if err != nil {
if pconn != c.currentConn() {
continue
}
} else {
// Convert pAddr to a netaddr.IPPort.
// This prevents pAddr from escaping.
var ok bool
ipp, ok = netaddr.FromStdAddr(pAddr.IP, pAddr.Port, pAddr.Zone)
if !ok {
return 0, netaddr.IPPort{}, errors.New("netaddr.FromStdAddr failed")
}
if err != nil && pconn != c.currentConn() {
// The connection changed underfoot. Try again.
continue
}
return n, ipp, err
}