Initial commit

Based on previous work of @neilalexander:
https://github.com/yggdrasil-network/yggdrasil-go@netstack

Signed-off-by: Vasyl Gello <vasek.gello@gmail.com>

contrib/netstack/netstack.go

@@ -0,0 +1,107 @@
+package netstack
+
+import (
+	"context"
+	"fmt"
+	"net"
+	"strconv"
+
+	"github.com/yggdrasil-network/yggdrasil-go/src/core"
+
+	"gvisor.dev/gvisor/pkg/tcpip"
+	"gvisor.dev/gvisor/pkg/tcpip/adapters/gonet"
+	"gvisor.dev/gvisor/pkg/tcpip/network/ipv6"
+	"gvisor.dev/gvisor/pkg/tcpip/stack"
+	"gvisor.dev/gvisor/pkg/tcpip/transport/icmp"
+	"gvisor.dev/gvisor/pkg/tcpip/transport/tcp"
+	"gvisor.dev/gvisor/pkg/tcpip/transport/udp"
+)
+
+type YggdrasilNetstack struct {
+	stack *stack.Stack
+}
+
+func CreateYggdrasilNetstack(ygg *core.Core) (*YggdrasilNetstack, error) {
+	s := &YggdrasilNetstack{
+		stack: stack.New(stack.Options{
+			NetworkProtocols:   []stack.NetworkProtocolFactory{ipv6.NewProtocol},
+			TransportProtocols: []stack.TransportProtocolFactory{tcp.NewProtocol, udp.NewProtocol, icmp.NewProtocol6},
+			HandleLocal:        true,
+		}),
+	}
+	if s.stack.HandleLocal() {
+		s.stack.AllowICMPMessage()
+	} else if err := s.stack.SetForwardingDefaultAndAllNICs(ipv6.ProtocolNumber, true); err != nil {
+		panic(err)
+	}
+	if err := s.NewYggdrasilNIC(ygg); err != nil {
+		return nil, fmt.Errorf("s.NewYggdrasilNIC: %s", err.String())
+	}
+	return s, nil
+}
+
+func convertToFullAddr(ip net.IP, port int) (tcpip.FullAddress, tcpip.NetworkProtocolNumber, error) {
+	addr := tcpip.Address{}
+	ip16 := ip.To16()
+	if ip16 != nil {
+		addr = tcpip.AddrFromSlice(ip16)
+	}
+	return tcpip.FullAddress{
+		NIC:  1,
+		Addr: addr,
+		Port: uint16(port),
+	}, ipv6.ProtocolNumber, nil
+}
+
+func convertToFullAddrFromString(endpoint string) (tcpip.FullAddress, tcpip.NetworkProtocolNumber, error) {
+	host, port, err := net.SplitHostPort(endpoint)
+	if err != nil {
+		return tcpip.FullAddress{}, 0, fmt.Errorf("net.SplitHostPort: %w", err)
+	}
+	pn := 80
+	if port != "" {
+		if pn, err = strconv.Atoi(port); err != nil {
+			return tcpip.FullAddress{}, 0, fmt.Errorf("strconv.Atoi: %w", err)
+		}
+	}
+	return convertToFullAddr(net.ParseIP(host), pn)
+}
+
+func (s *YggdrasilNetstack) DialContext(ctx context.Context, network, address string) (net.Conn, error) {
+	fa, pn, err := convertToFullAddrFromString(address)
+	if err != nil {
+		return nil, fmt.Errorf("convertToFullAddrFromString: %w", err)
+	}
+	switch network {
+	case "tcp", "tcp6":
+		return gonet.DialContextTCP(ctx, s.stack, fa, pn)
+	case "udp", "udp6":
+		conn, err := gonet.DialUDP(s.stack, nil, &fa, pn)
+		if err != nil {
+			return nil, fmt.Errorf("gonet.DialUDP: %w", err)
+		}
+		return conn, nil
+	default:
+		return nil, fmt.Errorf("not supported")
+	}
+}
+
+func (s *YggdrasilNetstack) DialTCP(addr *net.TCPAddr) (net.Conn, error) {
+	fa, pn, _ := convertToFullAddr(addr.IP, addr.Port)
+	return gonet.DialTCP(s.stack, fa, pn)
+}
+
+func (s *YggdrasilNetstack) DialUDP(addr *net.UDPAddr) (net.PacketConn, error) {
+	fa, pn, _ := convertToFullAddr(addr.IP, addr.Port)
+	return gonet.DialUDP(s.stack, nil, &fa, pn)
+}
+
+func (s *YggdrasilNetstack) ListenTCP(addr *net.TCPAddr) (net.Listener, error) {
+	fa, pn, _ := convertToFullAddr(addr.IP, addr.Port)
+	return gonet.ListenTCP(s.stack, fa, pn)
+}
+
+func (s *YggdrasilNetstack) ListenUDP(addr *net.UDPAddr) (net.PacketConn, error) {
+	fa, pn, _ := convertToFullAddr(addr.IP, addr.Port)
+	return gonet.DialUDP(s.stack, &fa, nil, pn)
+}