move ckr checks into the tunConn code

src/tuntap/ckr.go

@@ -132,23 +132,9 @@ func (c *cryptokey) isEnabled() bool {
 func (c *cryptokey) isValidLocalAddress(addr address.Address, addrlen int) bool {
 	c.mutexlocals.RLock()
 	defer c.mutexlocals.RUnlock()
-
-	ip := net.IP(addr[:addrlen])
-
-	if addrlen == net.IPv6len {
-		// Does this match our node's address?
-		if bytes.Equal(addr[:16], c.tun.addr[:16]) {
-			return true
-		}
-
-		// Does this match our node's subnet?
-		if bytes.Equal(addr[:8], c.tun.subnet[:8]) {
-			return true
-		}
-	}
-
 	// Does it match a configured CKR source?
 	if c.isEnabled() {
+		ip := net.IP(addr[:addrlen])
 		// Build our references to the routing sources
 		var routingsources *[]net.IPNet
 

src/tuntap/conn.go

@@ -6,6 +6,7 @@ import (
 	"time"
 
 	"github.com/yggdrasil-network/yggdrasil-go/src/address"
+	"github.com/yggdrasil-network/yggdrasil-go/src/crypto"
 	"github.com/yggdrasil-network/yggdrasil-go/src/util"
 	"github.com/yggdrasil-network/yggdrasil-go/src/yggdrasil"
 	"golang.org/x/net/icmp"
@@ -71,16 +72,62 @@ func (s *tunConn) reader() (err error) {
 				return e
 			}
 		} else if len(bs) > 0 {
-			if bs[0]&0xf0 == 0x60 {
+			ipv4 := len(bs) > 20 && bs[0]&0xf0 == 0x40
+			ipv6 := len(bs) > 40 && bs[0]&0xf0 == 0x60
+			isCGA := true
+			// Check source addresses
 			switch {
-				case bs[8] == 0x02 && !bytes.Equal(s.addr[:16], bs[8:24]): // source
+			case ipv6 && bs[8] == 0x02 && bytes.Equal(s.addr[:16], bs[8:24]): // source
-				case bs[8] == 0x03 && !bytes.Equal(s.snet[:8], bs[8:16]): // source
+			case ipv6 && bs[8] == 0x03 && bytes.Equal(s.snet[:8], bs[8:16]): // source
-				case bs[24] == 0x02 && !bytes.Equal(s.tun.addr[:16], bs[24:40]): // destination
+			default:
-				case bs[24] == 0x03 && !bytes.Equal(s.tun.subnet[:8], bs[24:32]): // destination
+				isCGA = false
+			}
+			// Check destiantion addresses
+			switch {
+			case ipv6 && bs[24] == 0x02 && bytes.Equal(s.tun.addr[:16], bs[24:40]): // destination
+			case ipv6 && bs[24] == 0x03 && bytes.Equal(s.tun.subnet[:8], bs[24:32]): // destination
+			default:
+				isCGA = false
+			}
+			// Decide how to handle the packet
+			var skip bool
+			switch {
+			case isCGA: // Allowed
+			case s.tun.ckr.isEnabled() && (ipv4 || ipv6):
+				var srcAddr address.Address
+				var dstAddr address.Address
+				var addrlen int
+				if ipv4 {
+					copy(srcAddr[:], bs[12:16])
+					copy(dstAddr[:], bs[16:20])
+					addrlen = 4
+				}
+				if ipv6 {
+					copy(srcAddr[:], bs[8:24])
+					copy(dstAddr[:], bs[24:40])
+					addrlen = 16
+				}
+				if !s.tun.ckr.isValidLocalAddress(dstAddr, addrlen) {
+					// The destination address isn't in our CKR allowed range
+					skip = true
+				} else if key, err := s.tun.ckr.getPublicKeyForAddress(srcAddr, addrlen); err == nil {
+					srcNodeID := crypto.GetNodeID(&key)
+					if s.conn.RemoteAddr() == *srcNodeID {
+						// This is the one allowed CKR case, where source and destination addresses are both good
+					} else {
+						// The CKR key associated with this address doesn't match the sender's NodeID
+						skip = true
+					}
+				} else {
+					// We have no CKR route for this source address
+					skip = true
+				}
+			default:
+				skip = true
+			}
+			if skip {
 				util.PutBytes(bs)
 				continue
-				default:
-				}
 			}
 			s.tun.send <- bs
 			s.stillAlive()
@@ -108,15 +155,62 @@ func (s *tunConn) writer() error {
 			if !ok {
 				return errors.New("send closed")
 			}
-			if bs[0]&0xf0 == 0x60 {
+			v4 := len(bs) > 20 && bs[0]&0xf0 == 0x40
+			v6 := len(bs) > 40 && bs[0]&0xf0 == 0x60
+			isCGA := true
+			// Check source addresses
 			switch {
-				case bs[8] == 0x02 && !bytes.Equal(s.tun.addr[:16], bs[8:24]): // source
+			case v6 && bs[8] == 0x02 && bytes.Equal(s.tun.addr[:16], bs[8:24]): // source
-				case bs[8] == 0x03 && !bytes.Equal(s.tun.subnet[:8], bs[8:16]): // source
+			case v6 && bs[8] == 0x03 && bytes.Equal(s.tun.subnet[:8], bs[8:16]): // source
-				case bs[24] == 0x02 && !bytes.Equal(s.addr[:16], bs[24:40]): // destination
-				case bs[24] == 0x03 && !bytes.Equal(s.snet[:8], bs[24:32]): // destination
-					continue
 			default:
+				isCGA = false
 			}
+			// Check destiantion addresses
+			switch {
+			case v6 && bs[24] == 0x02 && bytes.Equal(s.addr[:16], bs[24:40]): // destination
+			case v6 && bs[24] == 0x03 && bytes.Equal(s.snet[:8], bs[24:32]): // destination
+			default:
+				isCGA = false
+			}
+			// Decide how to handle the packet
+			var skip bool
+			switch {
+			case isCGA: // Allowed
+			case s.tun.ckr.isEnabled() && (v4 || v6):
+				var srcAddr address.Address
+				var dstAddr address.Address
+				var addrlen int
+				if v4 {
+					copy(srcAddr[:], bs[12:16])
+					copy(dstAddr[:], bs[16:20])
+					addrlen = 4
+				}
+				if v6 {
+					copy(srcAddr[:], bs[8:24])
+					copy(dstAddr[:], bs[24:40])
+					addrlen = 16
+				}
+				if !s.tun.ckr.isValidLocalAddress(srcAddr, addrlen) {
+					// The source address isn't in our CKR allowed range
+					skip = true
+				} else if key, err := s.tun.ckr.getPublicKeyForAddress(dstAddr, addrlen); err == nil {
+					dstNodeID := crypto.GetNodeID(&key)
+					if s.conn.RemoteAddr() == *dstNodeID {
+						// This is the one allowed CKR case, where source and destination addresses are both good
+					} else {
+						// The CKR key associated with this address doesn't match the sender's NodeID
+						skip = true
+					}
+				} else {
+					// We have no CKR route for this destination address... why do we have the packet in the first place?
+					skip = true
+				}
+			default:
+				skip = true
+			}
+			if skip {
+				util.PutBytes(bs)
+				continue
 			}
 			msg := yggdrasil.FlowKeyMessage{
 				FlowKey: util.GetFlowKey(bs),

src/tuntap/iface.go

@@ -2,7 +2,6 @@ package tuntap
 
 import (
 	"bytes"
-	"errors"
 	"net"
 	"time"
 
@@ -21,62 +20,6 @@ func (tun *TunAdapter) writer() error {
 		if n == 0 {
 			continue
 		}
-		var srcAddr address.Address
-		var dstAddr address.Address
-		var addrlen int
-		// Check whether the packet is IPv4, IPv6 or neither
-		if b[0]&0xf0 == 0x60 {
-			// IPv6 packet found
-			if len(b) < 40 {
-				// Packet was too short
-				util.PutBytes(b)
-				continue
-			}
-			// Extract the IPv6 addresses
-			copy(srcAddr[:16], b[8:24])
-			copy(dstAddr[:16], b[24:40])
-			addrlen = 16
-		} else if b[0]&0xf0 == 0x40 {
-			// IPv4 packet found
-			if len(b) < 20 {
-				// Packet was too short
-				util.PutBytes(b)
-				continue
-			}
-			// Extract the IPv4 addresses
-			copy(srcAddr[:4], b[12:16])
-			copy(dstAddr[:4], b[16:20])
-			addrlen = 4
-		} else {
-			// Neither IPv4 nor IPv6
-			return errors.New("Invalid address family")
-		}
-		// Check the crypto-key routing rules next
-		if tun.ckr.isEnabled() {
-			if !tun.ckr.isValidLocalAddress(dstAddr, addrlen) {
-				util.PutBytes(b)
-				continue
-			}
-			if srcAddr[0] != 0x02 && srcAddr[0] != 0x03 {
-				// TODO: is this check useful? this doesn't actually guarantee that the
-				// packet came from the configured public key for that remote, just that
-				// it came from *a* configured remote. at this stage we have no ability
-				// to know which Conn or public key was involved
-				if _, err := tun.ckr.getPublicKeyForAddress(srcAddr, addrlen); err != nil {
-					util.PutBytes(b)
-					continue
-				}
-			}
-		} else {
-			if addrlen != 16 {
-				util.PutBytes(b)
-				continue
-			}
-			if !bytes.Equal(tun.addr[:16], dstAddr[:16]) && !bytes.Equal(tun.subnet[:8], dstAddr[:8]) {
-				util.PutBytes(b)
-				continue
-			}
-		}
 		if tun.iface.IsTAP() {
 			sendndp := func(dstAddr address.Address) {
 				neigh, known := tun.icmpv6.getNeighbor(dstAddr)
@@ -86,6 +29,7 @@ func (tun *TunAdapter) writer() error {
 				}
 			}
 			peermac := net.HardwareAddr{0x00, 0x00, 0x00, 0x00, 0x00, 0x00}
+			var dstAddr address.Address
 			var peerknown bool
 			if b[0]&0xf0 == 0x40 {
 				dstAddr = tun.addr
@@ -183,10 +127,7 @@ func (tun *TunAdapter) readerPacketHandler(ch chan []byte) {
 		// From the IP header, work out what our source and destination addresses
 		// and node IDs are. We will need these in order to work out where to send
 		// the packet
-		var srcAddr address.Address
 		var dstAddr address.Address
-		var dstNodeID *crypto.NodeID
-		var dstNodeIDMask *crypto.NodeID
 		var dstSnet address.Subnet
 		var addrlen int
 		n := len(bs)
@@ -203,7 +144,6 @@ func (tun *TunAdapter) readerPacketHandler(ch chan []byte) {
 			}
 			// IPv6 address
 			addrlen = 16
-			copy(srcAddr[:addrlen], bs[8:])
 			copy(dstAddr[:addrlen], bs[24:])
 			copy(dstSnet[:addrlen/2], bs[24:])
 		} else if bs[0]&0xf0 == 0x40 {
@@ -217,7 +157,6 @@ func (tun *TunAdapter) readerPacketHandler(ch chan []byte) {
 			}
 			// IPv4 address
 			addrlen = 4
-			copy(srcAddr[:addrlen], bs[12:])
 			copy(dstAddr[:addrlen], bs[16:])
 		} else {
 			// Unknown address length or protocol, so drop the packet and ignore it
@@ -225,36 +164,22 @@ func (tun *TunAdapter) readerPacketHandler(ch chan []byte) {
 			continue
 		}
 		if tun.ckr.isEnabled() {
-			if !tun.ckr.isValidLocalAddress(srcAddr, addrlen) {
+			if addrlen != 16 || (!dstAddr.IsValid() && !dstSnet.IsValid()) {
-				continue
-			}
-			if !dstAddr.IsValid() && !dstSnet.IsValid() {
 				if key, err := tun.ckr.getPublicKeyForAddress(dstAddr, addrlen); err == nil {
 					// A public key was found, get the node ID for the search
-					dstNodeID = crypto.GetNodeID(&key)
+					dstNodeID := crypto.GetNodeID(&key)
-					// Do a quick check to ensure that the node ID refers to a vaild
+					dstAddr = *address.AddrForNodeID(dstNodeID)
-					// Yggdrasil address or subnet - this might be superfluous
+					dstSnet = *address.SubnetForNodeID(dstNodeID)
-					addr := *address.AddrForNodeID(dstNodeID)
+					addrlen = 16
-					copy(dstAddr[:], addr[:])
+				}
-					copy(dstSnet[:], addr[:])
+			}
-					// Are we certain we looked up a valid node?
+		}
-					if !dstAddr.IsValid() && !dstSnet.IsValid() {
+		if addrlen != 16 || (!dstAddr.IsValid() && !dstSnet.IsValid()) {
+			// Couldn't find this node's ygg IP
 			continue
 		}
-				} else {
-					// No public key was found in the CKR table so we've exhausted our options
-					continue
-				}
-			}
-		} else {
-			if addrlen != 16 {
-				continue
-			}
-			if !dstAddr.IsValid() && !dstSnet.IsValid() {
-				continue
-			}
-		}
 		// Do we have an active connection for this node address?
+		var dstNodeID, dstNodeIDMask *crypto.NodeID
 		tun.mutex.RLock()
 		session, isIn := tun.addrToConn[dstAddr]
 		if !isIn || session == nil {