{net/connstats,wgengine/magicsock}: fix packet counting in connstats

connstats currently increments the packet counter whenever it is called
to store a length of data, however when udp batch sending was introduced
we pass the length for a series of packages, and it is only incremented
ones, making it count wrongly if we are on a platform supporting udp
batches.

Updates tailscale/corp#22075

Signed-off-by: Kristoffer Dalby <kristoffer@tailscale.com>

wgengine/magicsock/derp.go

@@ -730,7 +730,7 @@ func (c *Conn) processDERPReadResult(dm derpReadResult, b []byte) (n int, ep *en
 
 	ep.noteRecvActivity(ipp, mono.Now())
 	if stats := c.stats.Load(); stats != nil {
-		stats.UpdateRxPhysical(ep.nodeAddr, ipp, dm.n)
+		stats.UpdateRxPhysical(ep.nodeAddr, ipp, 1, dm.n)
 	}
 	return n, ep
 }

wgengine/magicsock/endpoint.go

@@ -976,7 +976,7 @@ func (de *endpoint) send(buffs [][]byte) error {
 
 		// TODO(raggi): needs updating for accuracy, as in error conditions we may have partial sends.
 		if stats := de.c.stats.Load(); err == nil && stats != nil {
-			stats.UpdateTxPhysical(de.nodeAddr, udpAddr, txBytes)
+			stats.UpdateTxPhysical(de.nodeAddr, udpAddr, len(buffs), txBytes)
 		}
 	}
 	if derpAddr.IsValid() {
@@ -991,7 +991,7 @@ func (de *endpoint) send(buffs [][]byte) error {
 		}
 
 		if stats := de.c.stats.Load(); stats != nil {
-			stats.UpdateTxPhysical(de.nodeAddr, derpAddr, txBytes)
+			stats.UpdateTxPhysical(de.nodeAddr, derpAddr, 1, txBytes)
 		}
 		if allOk {
 			return nil

wgengine/magicsock/magicsock.go

@@ -1523,7 +1523,7 @@ func (c *Conn) receiveIP(b []byte, ipp netip.AddrPort, cache *ippEndpointCache)
 	ep.lastRecvUDPAny.StoreAtomic(now)
 	ep.noteRecvActivity(ipp, now)
 	if stats := c.stats.Load(); stats != nil {
-		stats.UpdateRxPhysical(ep.nodeAddr, ipp, len(b))
+		stats.UpdateRxPhysical(ep.nodeAddr, ipp, 1, len(b))
 	}
 	return ep, true
 }