Add Custom Clients and Servers

README.md

@@ -65,6 +65,8 @@ Features:
 * [node-endpoint-tcp-server](examples/node-endpoint-tcp-server/main.go)
 * [node-endpoint-tcp-client](examples/node-endpoint-tcp-client/main.go)
 * [node-endpoint-custom](examples/node-endpoint-custom/main.go)
+* [node-endpoint-custom-client](examples/node-endpoint-custom-client/main.go)
+* [node-endpoint-custom-server](examples/node-endpoint-custom-server/main.go)
 * [node-message-read](examples/node-message-read/main.go)
 * [node-message-write](examples/node-message-write/main.go)
 * [node-signature](examples/node-signature/main.go)

endpoint_client.go

@@ -2,6 +2,7 @@ package gomavlib
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"io"
 	"net"
@@ -13,7 +14,6 @@ import (
 var reconnectPeriod = 2 * time.Second
 
 type endpointClientConf interface {
-	isUDP() bool
 	getAddress() string
 	init(*Node) (Endpoint, error)
 }
@@ -27,10 +27,6 @@ type EndpointTCPClient struct {
 	Address string
 }
 
-func (EndpointTCPClient) isUDP() bool {
-	return false
-}
-
 func (conf EndpointTCPClient) getAddress() string {
 	return conf.Address
 }
@@ -50,10 +46,6 @@ type EndpointUDPClient struct {
 	Address string
 }
 
-func (EndpointUDPClient) isUDP() bool {
-	return true
-}
-
 func (conf EndpointUDPClient) getAddress() string {
 	return conf.Address
 }
@@ -67,6 +59,30 @@ func (conf EndpointUDPClient) init(node *Node) (Endpoint, error) {
 	return e, err
 }
 
+// EndpointCustomClient sets up a endpoint that works with a custom implementation
+// by providing a Connect func that returns a net.Conn.
+type EndpointCustomClient struct {
+	// domain name or IP of the server to connect to, example: 1.2.3.4:5600
+	Address string
+	// custom connect function that connects to the provided address
+	Connect func(address string) (net.Conn, error)
+	// the label of the protocol
+	Label string
+}
+
+func (conf EndpointCustomClient) getAddress() string {
+	return conf.Address
+}
+
+func (conf EndpointCustomClient) init(node *Node) (Endpoint, error) {
+	e := &endpointClient{
+		node: node,
+		conf: conf,
+	}
+	err := e.initialize()
+	return e, err
+}
+
 type endpointClient struct {
 	node *Node
 	conf endpointClientConf
@@ -103,16 +119,31 @@ func (e *endpointClient) oneChannelAtAtime() bool {
 
 func (e *endpointClient) connect() (io.ReadWriteCloser, error) {
 	network := func() string {
-		if e.conf.isUDP() {
+		switch e.conf.(type) {
+		case EndpointTCPClient:
+			return "tcp4"
+		case EndpointUDPClient:
 			return "udp4"
+		case EndpointCustomClient:
+			return "cust"
+		default:
+			return ""
 		}
-		return "tcp4"
 	}()
 
 	// in UDP, the only possible error is a DNS failure
 	// in TCP, the handshake must be completed
 	timedContext, timedContextClose := context.WithTimeout(e.ctx, e.node.ReadTimeout)
-	nconn, err := (&net.Dialer{}).DialContext(timedContext, network, e.conf.getAddress())
+	nconn, err := func() (net.Conn, error) {
+		if network == "cust" {
+			customConf := e.conf.(EndpointCustomClient)
+			if customConf.Connect == nil {
+				return nil, errors.New("no connect function provided on custom endpoint")
+			}
+			return customConf.Connect(customConf.Address)
+		}
+		return (&net.Dialer{}).DialContext(timedContext, network, e.conf.getAddress())
+	}()
 	timedContextClose()
 
 	if err != nil {
@@ -154,9 +185,18 @@ func (e *endpointClient) provide() (string, io.ReadWriteCloser, error) {
 
 func (e *endpointClient) label() string {
 	return fmt.Sprintf("%s:%s", func() string {
-		if e.conf.isUDP() {
+		switch conf := e.conf.(type) {
+		case EndpointTCPClient:
+			return "tcp"
+		case EndpointUDPClient:
 			return "udp"
+		case EndpointCustomClient:
+			if conf.Label != "" {
+				return conf.Label
+			}
+			return "custom"
+		default:
+			return "unknown"
 		}
-		return "tcp"
 	}(), e.conf.getAddress())
 }

endpoint_server.go

@@ -1,17 +1,16 @@
 package gomavlib
 
 import (
+	"errors"
 	"fmt"
 	"io"
 	"net"
 
-	"github.com/pion/transport/v2/udp"
-
 	"github.com/bluenviron/gomavlib/v3/pkg/timednetconn"
+	"github.com/pion/transport/v2/udp"
 )
 
 type endpointServerConf interface {
-	isUDP() bool
 	getAddress() string
 	init(*Node) (Endpoint, error)
 }
@@ -25,10 +24,6 @@ type EndpointTCPServer struct {
 	Address string
 }
 
-func (EndpointTCPServer) isUDP() bool {
-	return false
-}
-
 func (conf EndpointTCPServer) getAddress() string {
 	return conf.Address
 }
@@ -50,10 +45,6 @@ type EndpointUDPServer struct {
 	Address string
 }
 
-func (EndpointUDPServer) isUDP() bool {
-	return true
-}
-
 func (conf EndpointUDPServer) getAddress() string {
 	return conf.Address
 }
@@ -67,6 +58,32 @@ func (conf EndpointUDPServer) init(node *Node) (Endpoint, error) {
 	return e, err
 }
 
+// EndpointCustomServer sets up a endpoint that works with custom implementations
+// by providing a custom Listen func that returns a net.Listener.
+// This allows you to use custom protocols that conform to the net.listner.
+// A use case could be to add encrypted protocol implementations like DTLS or TCP with TLS.
+type EndpointCustomServer struct {
+	// listen address, example: 0.0.0.0:5600
+	Address string
+	// function to invoke when server should start listening
+	Listen func(address string) (net.Listener, error)
+	// the label of the protocol
+	Label string
+}
+
+func (conf EndpointCustomServer) getAddress() string {
+	return conf.Address
+}
+
+func (conf EndpointCustomServer) init(node *Node) (Endpoint, error) {
+	e := &endpointServer{
+		node: node,
+		conf: conf,
+	}
+	err := e.initialize()
+	return e, err
+}
+
 type endpointServer struct {
 	node *Node
 	conf endpointServerConf
@@ -83,7 +100,8 @@ func (e *endpointServer) initialize() error {
 		return fmt.Errorf("invalid address")
 	}
 
-	if e.conf.isUDP() {
+	switch conf := e.conf.(type) {
+	case EndpointUDPServer:
 		var addr *net.UDPAddr
 		addr, err = net.ResolveUDPAddr("udp4", e.conf.getAddress())
 		if err != nil {
@@ -94,11 +112,21 @@ func (e *endpointServer) initialize() error {
 		if err != nil {
 			return err
 		}
-	} else {
+
+	case EndpointTCPServer:
 		e.listener, err = net.Listen("tcp4", e.conf.getAddress())
 		if err != nil {
 			return err
 		}
+
+	case EndpointCustomServer:
+		e.listener, err = conf.Listen(e.conf.getAddress())
+		if err != nil {
+			return err
+		}
+
+	default:
+		return errors.New("unsupported server-type")
 	}
 
 	e.terminate = make(chan struct{})
@@ -130,10 +158,19 @@ func (e *endpointServer) provide() (string, io.ReadWriteCloser, error) {
 	}
 
 	label := fmt.Sprintf("%s:%s", func() string {
-		if e.conf.isUDP() {
+		switch conf := e.conf.(type) {
+		case EndpointTCPServer:
+			return "tcp"
+		case EndpointUDPServer:
 			return "udp"
+		case EndpointCustomServer:
+			if conf.Label != "" {
+				return conf.Label
+			}
+			return "custom"
+		default:
+			return "unknown"
 		}
-		return "tcp"
 	}(), nconn.RemoteAddr())
 
 	conn := timednetconn.New(

examples/node-endpoint-custom-client/main.go

@@ -0,0 +1,50 @@
+// Package main contains an example.
+package main
+
+import (
+	"crypto/tls"
+	"log"
+	"net"
+
+	"github.com/bluenviron/gomavlib/v3"
+	"github.com/bluenviron/gomavlib/v3/pkg/dialects/ardupilotmega"
+)
+
+// this example shows how to:
+// 1) create a node which communicates with a custom TCP/TLS endpoint in client mode.
+// 2) print incoming messages.
+
+func main() {
+	// create a node which communicates with a TCP endpoint in client mode
+	node := &gomavlib.Node{
+		Endpoints: []gomavlib.EndpointConf{
+			gomavlib.EndpointCustomClient{
+				Address: "127.0.0.1:5600",
+				Connect: func(address string) (net.Conn, error) {
+					tlsConfig := &tls.Config{
+						// skip checking the certificate against a CA (just set to true for simplicity of this example)
+						InsecureSkipVerify: true,
+					}
+
+					return tls.Dial("tcp", address, tlsConfig)
+				},
+				Label: "TCP/TLS",
+			},
+		},
+		Dialect:     ardupilotmega.Dialect,
+		OutVersion:  gomavlib.V2, // change to V1 if you're unable to communicate with the target
+		OutSystemID: 10,
+	}
+	err := node.Initialize()
+	if err != nil {
+		panic(err)
+	}
+	defer node.Close()
+
+	// print incoming messages
+	for evt := range node.Events() {
+		if frm, ok := evt.(*gomavlib.EventFrame); ok {
+			log.Printf("received: id=%d, %+v\n", frm.Message().GetID(), frm.Message())
+		}
+	}
+}

examples/node-endpoint-custom-server/.gitignore

@@ -0,0 +1 @@
+certs