Minor cleanup.

router/dataplane.go

@@ -1258,8 +1258,6 @@ func (p *scionPacketProcessor) respInvalidDstIA() disposition {
 // Provided that underlying network infrastructure prevents address spoofing,
 // this check prevents malicious end hosts in the local AS from bypassing the
 // SrcIA checks by disguising packets as transit traffic.
-//
-// TODO(multi_underlay): All or part of this check should move to the underlay.
 func (p *scionPacketProcessor) validateTransitUnderlaySrc() disposition {
 	if p.path.IsFirstHop() || p.pkt.Ingress != 0 {
 		// not a transit packet, nothing to check
@@ -1271,6 +1269,8 @@ func (p *scionPacketProcessor) validateTransitUnderlaySrc() disposition {
 		// Drop
 		return errorDiscard("error", invalidSrcAddrForTransit)
 	}
+
+	// TODO(multi_underlay): This check should move to the underlay, in siblingLink.
 	src, okS := netip.AddrFromSlice(p.pkt.SrcAddr.IP)
 	if !(okS && ingressLink.Remote().Addr() == src) {
 		// Drop

router/underlayproviders/udpip/udpip.go

@@ -491,7 +491,6 @@ func (l *externalLink) SendBlocking(p *router.Packet) {
 	l.egressQ <- p
 }
 
-// TODO(multi_underlay): try and move code common to all links back into the router.
 func (l *externalLink) receive(size int, srcAddr *net.UDPAddr, pkt *router.Packet) {
 	metrics := l.metrics
 	sc := router.ClassOfSize(size)
@@ -506,7 +505,6 @@ func (l *externalLink) receive(size int, srcAddr *net.UDPAddr, pkt *router.Packe
 		return
 	}
 
-	pkt.RawPacket = pkt.RawPacket[:size] // Update size; readBatch does not.
 	pkt.Ingress = l.ifID
 	pkt.SrcAddr = srcAddr
 	// TODO(multi_underlay): would an expected/src check be useful here?
@@ -642,7 +640,6 @@ func (l *siblingLink) SendBlocking(p *router.Packet) {
 	l.egressQ <- p
 }
 
-// TODO(multi_underlay): try and move code common to all links back into the router.
 func (l *siblingLink) receive(size int, srcAddr *net.UDPAddr, pkt *router.Packet) {
 	metrics := l.metrics
 	sc := router.ClassOfSize(size)
@@ -656,7 +653,6 @@ func (l *siblingLink) receive(size int, srcAddr *net.UDPAddr, pkt *router.Packet
 		metrics[sc].DroppedPacketsInvalid.Inc()
 	}
 
-	pkt.RawPacket = pkt.RawPacket[:size]
 	pkt.Ingress = 0
 	pkt.SrcAddr = srcAddr
 	// TODO(multi_underlay): can move expected/src check here.
@@ -773,7 +769,6 @@ func (l *internalLink) receive(size int, srcAddr *net.UDPAddr, pkt *router.Packe
 		return
 	}
 
-	pkt.RawPacket = pkt.RawPacket[:size] // Update size; readBatch does not.
 	pkt.Ingress = 0
 	pkt.SrcAddr = srcAddr
 	select {