added response timeout

1. changed examples to use this package
2. response timeout issue is recorded in original repo at dustin#43

README.markdown

@@ -6,3 +6,11 @@ some preliminary work on `SUBSCRIBE` support from
 
 [shelby]: http://tools.ietf.org/html/draft-shelby-core-coap-01
 [coap]: http://tools.ietf.org/html/rfc7252
+
+## Differences from original `dustin/go-coap`
+
+1. Added minor helper function to populate URI options.
+2. Added configurable receive timeout in backgwards compatible way.  Changed `ResponseTimeout` variable to `DefaultResponseTimeout` to emphasise its role change and to be able to track down its usage within package.
+3. Example programs package references have been changed from `dustin/go-coap` to `Kulak/go-coap`.
+
+Motivation for all this change: need to support existing application functionality.

client.go

@@ -6,9 +6,9 @@ import (
 )
 
 const (
-	// ResponseTimeout is the amount of time to wait for a
+	// DefaultResponseTimeout is the amount of time to wait for a
 	// response.
-	ResponseTimeout = time.Second * 2
+	DefaultResponseTimeout = time.Second * 2
 	// ResponseRandomFactor is a multiplier for response backoff.
 	ResponseRandomFactor = 1.5
 	// MaxRetransmit is the maximum number of times a message will
@@ -18,12 +18,18 @@ const (
 
 // Conn is a CoAP client connection.
 type Conn struct {
-	conn *net.UDPConn
-	buf  []byte
+	conn            *net.UDPConn
+	buf             []byte
+	responseTimeout time.Duration
 }
 
 // Dial connects a CoAP client.
 func Dial(n, addr string) (*Conn, error) {
+	return DialWithTimeout(n, addr, DefaultResponseTimeout)
+}
+
+// DialWithTimeout provides control of response timeout.
+func DialWithTimeout(n, addr string, responseTimeout time.Duration) (*Conn, error) {
 	uaddr, err := net.ResolveUDPAddr(n, addr)
 	if err != nil {
 		return nil, err
@@ -34,7 +40,7 @@ func Dial(n, addr string) (*Conn, error) {
 		return nil, err
 	}
 
-	return &Conn{s, make([]byte, maxPktLen)}, nil
+	return &Conn{s, make([]byte, maxPktLen), responseTimeout}, nil
 }
 
 // Send a message.  Get a response if there is one.
@@ -48,7 +54,7 @@ func (c *Conn) Send(req Message) (*Message, error) {
 		return nil, nil
 	}
 
-	rv, err := Receive(c.conn, c.buf)
+	rv, err := Receive(c.conn, c.buf, c.responseTimeout)
 	if err != nil {
 		return nil, err
 	}
@@ -58,7 +64,7 @@ func (c *Conn) Send(req Message) (*Message, error) {
 
 // Receive a message.
 func (c *Conn) Receive() (*Message, error) {
-	rv, err := Receive(c.conn, c.buf)
+	rv, err := Receive(c.conn, c.buf, c.responseTimeout)
 	if err != nil {
 		return nil, err
 	}

client_test.go

@@ -0,0 +1,51 @@
+package coap_test
+
+import (
+	"testing"
+
+	coap "github.com/Kulak/go-coap"
+
+	"time"
+
+	"math"
+)
+
+func TestTimeoutDefaults(t *testing.T) {
+	testTimeout(t, coap.DefaultResponseTimeout)
+}
+
+func TestTimeout6sec(t *testing.T) {
+	testTimeout(t, 6*time.Second)
+}
+
+func testTimeout(t *testing.T, expectedTimeout time.Duration) {
+	// send to IP address without CoAP EP
+	req := coap.Message{
+		Type:      coap.Confirmable,
+		Code:      coap.GET,
+		MessageID: 12345,
+		Payload:   []byte("undeliverable"),
+	}
+	req.SetOption(coap.MaxAge, 3)
+	req.SetPathString("/some/path")
+
+	c, err := coap.DialWithTimeout("udp", "192.168.254.254:5683", expectedTimeout)
+	if err != nil {
+		t.Errorf("Error dialing: %v", err)
+		return
+	}
+
+	start := time.Now()
+	_, err = c.Send(req)
+	end := time.Now()
+	timeout := end.Sub(start)
+	if err != nil {
+		// that's not going to get printed unless test fails
+		t.Logf("Error sending request: %v", err)
+		if math.Abs(timeout.Seconds()-expectedTimeout.Seconds()) > 0.1 {
+			t.Fatalf("Expected timeout %v, got %v", expectedTimeout, timeout)
+		}
+		return
+	}
+	t.Fatal("Response shall timeout.")
+}

example/client/goap_client.go

@@ -3,7 +3,7 @@ package main
 import (
 	"log"
 
-	"github.com/dustin/go-coap"
+	"github.com/Kulak/go-coap"
 )
 
 func main() {

example/obsclient/obsclient.go

@@ -3,7 +3,7 @@ package main
 import (
 	"log"
 
-	"github.com/dustin/go-coap"
+	"github.com/Kulak/go-coap"
 )
 
 func main() {

example/obsserver/obsserver.go

@@ -6,7 +6,7 @@ import (
 	"net"
 	"time"
 
-	"github.com/dustin/go-coap"
+	"github.com/Kulak/go-coap"
 )
 
 func periodicTransmitter(l *net.UDPConn, a *net.UDPAddr, m *coap.Message) {

example/server/coap_server.go

@@ -4,7 +4,7 @@ import (
 	"log"
 	"net"
 
-	"github.com/dustin/go-coap"
+	"github.com/Kulak/go-coap"
 )
 
 func main() {

server.go

@@ -57,8 +57,8 @@ func Transmit(l *net.UDPConn, a *net.UDPAddr, m Message) error {
 }
 
 // Receive a message.
-func Receive(l *net.UDPConn, buf []byte) (Message, error) {
-	l.SetReadDeadline(time.Now().Add(ResponseTimeout))
+func Receive(l *net.UDPConn, buf []byte, responseTimeout time.Duration) (Message, error) {
+	l.SetReadDeadline(time.Now().Add(responseTimeout))
 
 	nr, _, err := l.ReadFromUDP(buf)
 	if err != nil {