MPTCP suppport

src/core/link.go

@@ -36,6 +36,7 @@ type links struct {
 	unix  *linkUNIX  // UNIX interface support
 	socks *linkSOCKS // SOCKS interface support
 	quic  *linkQUIC  // QUIC interface support
+	mptcp *linkMPTCP // QUIC interface support
 	// _links can only be modified safely from within the links actor
 	_links map[linkInfo]*link // *link is nil if connection in progress
 }
@@ -95,6 +96,7 @@ func (l *links) init(c *Core) error {
 	l.unix = l.newLinkUNIX()
 	l.socks = l.newLinkSOCKS()
 	l.quic = l.newLinkQUIC()
+	l.mptcp = l.newLinkMPTCP()
 	l._links = make(map[linkInfo]*link)
 
 	var listeners []ListenAddress
@@ -421,6 +423,8 @@ func (l *links) listen(u *url.URL, sintf string) (*Listener, error) {
 		protocol = l.unix
 	case "quic":
 		protocol = l.quic
+	case "mptcp":
+		protocol = l.mptcp
 	default:
 		cancel()
 		return nil, ErrLinkUnrecognisedSchema

src/core/link_mptcp.go

@@ -0,0 +1,154 @@
+package core
+
+import (
+	"context"
+	"fmt"
+	"net"
+	"net/url"
+	"strconv"
+	"time"
+
+	"github.com/Arceliar/phony"
+)
+
+type linkMPTCP struct {
+	phony.Inbox
+	*links
+	listenconfig *net.ListenConfig
+	_listeners   map[*Listener]context.CancelFunc
+}
+
+func (l *links) newLinkMPTCP() *linkMPTCP {
+	lt := &linkMPTCP{
+		links: l,
+		listenconfig: &net.ListenConfig{
+			KeepAlive: -1,
+		},
+		_listeners: map[*Listener]context.CancelFunc{},
+	}
+	lt.listenconfig.Control = lt.tcp.tcpContext
+	lt.listenconfig.SetMultipathTCP(true)
+	return lt
+}
+
+func (l *linkMPTCP) dialersFor(url *url.URL, info linkInfo) ([]*tcpDialer, error) {
+	host, p, err := net.SplitHostPort(url.Host)
+	if err != nil {
+		return nil, err
+	}
+	port, err := strconv.Atoi(p)
+	if err != nil {
+		return nil, err
+	}
+	ips, err := net.LookupIP(host)
+	if err != nil {
+		return nil, err
+	}
+	dialers := make([]*tcpDialer, 0, len(ips))
+	for _, ip := range ips {
+		addr := &net.TCPAddr{
+			IP:   ip,
+			Port: port,
+		}
+		dialer, err := l.dialerFor(addr, info.sintf)
+		if err != nil {
+			continue
+		}
+		dialers = append(dialers, &tcpDialer{
+			info:   info,
+			dialer: dialer,
+			addr:   addr,
+		})
+	}
+	return dialers, nil
+}
+
+func (l *linkMPTCP) dial(ctx context.Context, url *url.URL, info linkInfo, options linkOptions) (net.Conn, error) {
+	dialers, err := l.dialersFor(url, info)
+	if err != nil {
+		return nil, err
+	}
+	if len(dialers) == 0 {
+		return nil, nil
+	}
+	for _, d := range dialers {
+		var conn net.Conn
+		conn, err = d.dialer.DialContext(ctx, "tcp", d.addr.String())
+		if err != nil {
+			l.core.log.Warnf("Failed to connect to %s: %s", d.addr, err)
+			continue
+		}
+		return conn, nil
+	}
+	return nil, err
+}
+
+func (l *linkMPTCP) listen(ctx context.Context, url *url.URL, sintf string) (net.Listener, error) {
+	hostport := url.Host
+	if sintf != "" {
+		if host, port, err := net.SplitHostPort(hostport); err == nil {
+			hostport = fmt.Sprintf("[%s%%%s]:%s", host, sintf, port)
+		}
+	}
+	return l.listenconfig.Listen(ctx, "tcp", hostport)
+}
+
+func (l *linkMPTCP) dialerFor(dst *net.TCPAddr, sintf string) (*net.Dialer, error) {
+	if dst.IP.IsLinkLocalUnicast() {
+		if sintf != "" {
+			dst.Zone = sintf
+		}
+		if dst.Zone == "" {
+			return nil, fmt.Errorf("link-local address requires a zone")
+		}
+	}
+	dialer := &net.Dialer{
+		Timeout:   time.Second * 5,
+		KeepAlive: -1,
+		Control:   l.tcp.tcpContext,
+	}
+	dialer.SetMultipathTCP(true)
+	if sintf != "" {
+		dialer.Control = l.tcp.getControl(sintf)
+		ief, err := net.InterfaceByName(sintf)
+		if err != nil {
+			return nil, fmt.Errorf("interface %q not found", sintf)
+		}
+		if ief.Flags&net.FlagUp == 0 {
+			return nil, fmt.Errorf("interface %q is not up", sintf)
+		}
+		addrs, err := ief.Addrs()
+		if err != nil {
+			return nil, fmt.Errorf("interface %q addresses not available: %w", sintf, err)
+		}
+		for addrindex, addr := range addrs {
+			src, _, err := net.ParseCIDR(addr.String())
+			if err != nil {
+				continue
+			}
+			if !src.IsGlobalUnicast() && !src.IsLinkLocalUnicast() {
+				continue
+			}
+			bothglobal := src.IsGlobalUnicast() == dst.IP.IsGlobalUnicast()
+			bothlinklocal := src.IsLinkLocalUnicast() == dst.IP.IsLinkLocalUnicast()
+			if !bothglobal && !bothlinklocal {
+				continue
+			}
+			if (src.To4() != nil) != (dst.IP.To4() != nil) {
+				continue
+			}
+			if bothglobal || bothlinklocal || addrindex == len(addrs)-1 {
+				dialer.LocalAddr = &net.TCPAddr{
+					IP:   src,
+					Port: 0,
+					Zone: sintf,
+				}
+				break
+			}
+		}
+		if dialer.LocalAddr == nil {
+			return nil, fmt.Errorf("no suitable source address found on interface %q", sintf)
+		}
+	}
+	return dialer, nil
+}