BGP connection on a speecified interface (including which is associated VRF) using syscall SO_BINDTODEVICE

6 files changed, 20 insertions, 7 deletions

diff --git a/pkg/server/fsm.go b/pkg/server/fsm.go
index ae102812..b06ddd5d 100644
--- a/pkg/server/fsm.go
+++ b/pkg/server/fsm.go
@@ -491,7 +491,7 @@ func (h *fsmHandler) connectLoop(ctx context.Context, wg *sync.WaitGroup) {
 	defer wg.Done()
 	fsm := h.fsm
 
-	retry, addr, port, password, ttl, ttlMin, localAddress := func() (int, string, int, string, uint8, uint8, string) {
+	retry, addr, port, password, ttl, ttlMin, localAddress, bindInterface := func() (int, string, int, string, uint8, uint8, string, string) {
 		fsm.lock.RLock()
 		defer fsm.lock.RUnlock()
 
@@ -518,7 +518,7 @@ func (h *fsmHandler) connectLoop(ctx context.Context, wg *sync.WaitGroup) {
 				ttl = fsm.pConf.EbgpMultihop.Config.MultihopTtl
 			}
 		}
-		return tick, addr, port, password, ttl, ttlMin, fsm.pConf.Transport.Config.LocalAddress
+		return tick, addr, port, password, ttl, ttlMin, fsm.pConf.Transport.Config.LocalAddress, fsm.pConf.Transport.Config.BindInterface
 	}()
 
 	tick := minConnectRetryInterval
@@ -553,7 +553,7 @@ func (h *fsmHandler) connectLoop(ctx context.Context, wg *sync.WaitGroup) {
 				LocalAddr: laddr,
 				Timeout:   time.Duration(tick-1) * time.Second,
 				Control: func(network, address string, c syscall.RawConn) error {
-					return dialerControl(network, address, c, ttl, ttlMin, password)
+					return dialerControl(network, address, c, ttl, ttlMin, password, bindInterface)
 				},
 			}
 
diff --git a/pkg/server/grpc_server.go b/pkg/server/grpc_server.go
index 0d6f7d9c..2540e685 100644
--- a/pkg/server/grpc_server.go
+++ b/pkg/server/grpc_server.go
@@ -655,6 +655,7 @@ func newNeighborFromAPIStruct(a *api.Peer) (*config.Neighbor, error) {
 		pconf.Transport.Config.LocalAddress = a.Transport.LocalAddress
 		pconf.Transport.Config.PassiveMode = a.Transport.PassiveMode
 		pconf.Transport.Config.RemotePort = uint16(a.Transport.RemotePort)
+		pconf.Transport.Config.BindInterface = a.Transport.BindInterface
 	}
 	if a.EbgpMultihop != nil {
 		pconf.EbgpMultihop.Config.Enabled = a.EbgpMultihop.Enabled
diff --git a/pkg/server/server.go b/pkg/server/server.go
index 82efeb6a..d77512f5 100644
--- a/pkg/server/server.go
+++ b/pkg/server/server.go
@@ -250,6 +250,7 @@ func (s *BgpServer) passConnToPeer(conn *net.TCPConn) {
 		}
 		peer.fsm.lock.RLock()
 		localAddr := peer.fsm.pConf.Transport.Config.LocalAddress
+		bindInterface := peer.fsm.pConf.Transport.Config.BindInterface
 		peer.fsm.lock.RUnlock()
 		localAddrValid := func(laddr string) bool {
 			if laddr == "0.0.0.0" || laddr == "::" {
@@ -262,12 +263,13 @@ func (s *BgpServer) passConnToPeer(conn *net.TCPConn) {
 			}
 
 			host, _, _ := net.SplitHostPort(l.String())
-			if host != laddr {
+			if host != laddr && bindInterface == "" {
 				log.WithFields(log.Fields{
 					"Topic":           "Peer",
 					"Key":             remoteAddr,
 					"Configured addr": laddr,
 					"Addr":            host,
+					"BindInterface":   bindInterface,
 				}).Info("Mismatched local address")
 				return false
 			}
diff --git a/pkg/server/sockopt.go b/pkg/server/sockopt.go
index e2b1c086..0aab0ba9 100644
--- a/pkg/server/sockopt.go
+++ b/pkg/server/sockopt.go
@@ -39,7 +39,7 @@ func setTCPMinTTLSockopt(conn *net.TCPConn, ttl int) error {
 	return setTcpMinTTLSockopt(conn, ttl)
 }
 
-func dialerControl(network, address string, c syscall.RawConn, ttl, ttlMin uint8, password string) error {
+func dialerControl(network, address string, c syscall.RawConn, ttl, ttlMin uint8, password string, bindInterface string) error {
 	if password != "" {
 		log.WithFields(log.Fields{
 			"Topic": "Peer",
diff --git a/pkg/server/sockopt_linux.go b/pkg/server/sockopt_linux.go
index 31df8397..203087ab 100644
--- a/pkg/server/sockopt_linux.go
+++ b/pkg/server/sockopt_linux.go
@@ -103,7 +103,7 @@ func setTCPMinTTLSockopt(conn *net.TCPConn, ttl int) error {
 	return setsockOptInt(sc, level, name, ttl)
 }
 
-func dialerControl(network, address string, c syscall.RawConn, ttl, minTtl uint8, password string) error {
+func dialerControl(network, address string, c syscall.RawConn, ttl, minTtl uint8, password string, bindInterface string) error {
 	family := syscall.AF_INET
 	raddr, _ := net.ResolveTCPAddr("tcp", address)
 	if raddr.IP.To4() == nil {
@@ -161,5 +161,15 @@ func dialerControl(network, address string, c syscall.RawConn, ttl, minTtl uint8
 			return sockerr
 		}
 	}
+	if bindInterface != "" {
+		if err := c.Control(func(fd uintptr) {
+			sockerr = os.NewSyscallError("setsockopt", syscall.SetsockoptString(int(fd), syscall.SOL_SOCKET, syscall.SO_BINDTODEVICE, bindInterface))
+		}); err != nil {
+			return err
+		}
+		if sockerr != nil {
+			return sockerr
+		}
+	}
 	return nil
 }
diff --git a/pkg/server/sockopt_openbsd.go b/pkg/server/sockopt_openbsd.go
index e65aabe0..3d6825e2 100644
--- a/pkg/server/sockopt_openbsd.go
+++ b/pkg/server/sockopt_openbsd.go
@@ -403,7 +403,7 @@ func setTCPMinTTLSockopt(conn *net.TCPConn, ttl int) error {
 	return setsockOptInt(sc, level, name, ttl)
 }
 
-func dialerControl(network, address string, c syscall.RawConn, ttl, minTtl uint8, password string) error {
+func dialerControl(network, address string, c syscall.RawConn, ttl, minTtl uint8, password string, bindInterface string) error {
 	if password != "" {
 		log.WithFields(log.Fields{
 			"Topic": "Peer",