Add initial crypto-key routing handlers

src/yggdrasil/ckr.go

@@ -0,0 +1,104 @@
+package yggdrasil
+
+import (
+	"encoding/hex"
+	"errors"
+	"net"
+	"sort"
+)
+
+// This module implements crypto-key routing, similar to Wireguard, where we
+// allow traffic for non-Yggdrasil ranges to be routed over Yggdrasil.
+
+type cryptokey struct {
+	core       *Core
+	enabled    bool
+	ipv4routes []cryptokey_route
+	ipv6routes []cryptokey_route
+}
+
+type cryptokey_route struct {
+	subnet      net.IPNet
+	destination []byte
+}
+
+func (c *cryptokey) init(core *Core) {
+	c.core = core
+	c.ipv4routes = make([]cryptokey_route, 0)
+	c.ipv6routes = make([]cryptokey_route, 0)
+}
+
+func (c *cryptokey) isEnabled() bool {
+	return c.enabled
+}
+
+func (c *cryptokey) addRoute(cidr string, dest string) error {
+	// Is the CIDR we've been given valid?
+	_, ipnet, err := net.ParseCIDR(cidr)
+	if err != nil {
+		return err
+	}
+
+	// Get the prefix length and size
+	prefixlen, prefixsize := ipnet.Mask.Size()
+
+	// Check if the prefix is IPv4 or IPv6
+	if prefixsize == net.IPv6len*8 {
+		// IPv6
+		for _, route := range c.ipv6routes {
+			// Do we already have a route for this subnet?
+			routeprefixlen, _ := route.subnet.Mask.Size()
+			if route.subnet.IP.Equal(ipnet.IP) && routeprefixlen == prefixlen {
+				return errors.New("IPv6 route already exists")
+			}
+		}
+		// Decode the public key
+		if boxPubKey, err := hex.DecodeString(dest); err != nil {
+			return err
+		} else {
+			// Add the new crypto-key route
+			c.ipv6routes = append(c.ipv6routes, cryptokey_route{
+				subnet:      *ipnet,
+				destination: boxPubKey,
+			})
+			// Sort so most specific routes are first
+			sort.Slice(c.ipv6routes, func(i, j int) bool {
+				im, _ := c.ipv6routes[i].subnet.Mask.Size()
+				jm, _ := c.ipv6routes[j].subnet.Mask.Size()
+				return im > jm
+			})
+			return nil
+		}
+	} else if prefixsize == net.IPv4len*8 {
+		// IPv4
+		return errors.New("IPv4 not supported at this time")
+	}
+	return errors.New("Unspecified error")
+}
+
+func (c *cryptokey) getPublicKeyForAddress(addr string) (boxPubKey, error) {
+	ipaddr := net.ParseIP(addr)
+
+	if ipaddr.To4() == nil {
+		// IPv6
+		for _, route := range c.ipv6routes {
+			if route.subnet.Contains(ipaddr) {
+				var box boxPubKey
+				copy(box[:boxPubKeyLen], route.destination)
+				return box, nil
+			}
+		}
+	} else {
+		// IPv4
+		return boxPubKey{}, errors.New("IPv4 not supported at this time")
+		/*
+			    for _, route := range c.ipv4routes {
+						if route.subnet.Contains(ipaddr) {
+							return route.destination, nil
+						}
+					}
+		*/
+	}
+
+	return boxPubKey{}, errors.New("No route")
+}