Handle http redirect (#4)

- Fixed panic if req.Body is nil or basicAuth is not set
- Switched over to http.DefaultTransport if RoundTripper is not provided

Closes #2, #3

negotiator.go

@@ -14,7 +14,19 @@ type Negotiator struct{ http.RoundTripper }
 //RoundTrip sends the request to the server, handling any authentication
 //re-sends as needed.
 func (l Negotiator) RoundTrip(req *http.Request) (res *http.Response, err error) {
+	// Use default round tripper if not provided
+	rt := l.RoundTripper
+	if rt == nil {
+		rt = http.DefaultTransport
+	}
+	// If it is not basic auth, just round trip the request as usual
+	reqauth := authheader(req.Header.Get("Authorization"))
+	if !reqauth.IsBasic() {
+		return rt.RoundTrip(req)
+	}
+	// Save request body
 	body := bytes.Buffer{}
+	if req.Body != nil {
 		_, err = body.ReadFrom(req.Body)
 		if err != nil {
 			return nil, err
@@ -22,38 +34,36 @@ func (l Negotiator) RoundTrip(req *http.Request) (res *http.Response, err error)
 
 		req.Body.Close()
 		req.Body = ioutil.NopCloser(bytes.NewReader(body.Bytes()))
-
-	reqauth := authheader(req.Header.Get("Authorization"))
-	if reqauth.IsBasic() {
+	}
 	// first try anonymous, in case the server still finds us
 	// authenticated from previous traffic
 	req.Header.Del("Authorization")
-
-		res, err = l.RoundTripper.RoundTrip(req)
+	res, err = rt.RoundTrip(req)
 	if err != nil {
 		return nil, err
 	}
-		if res.StatusCode != 401 {
+	if res.StatusCode != http.StatusUnauthorized {
 		return res, err
 	}
-	}
 
 	resauth := authheader(res.Header.Get("Www-Authenticate"))
 	if !resauth.IsNegotiate() {
 		// Unauthorized, Negotiate not requested, let's try with basic auth
-		res.Body.Close()
 		req.Header.Set("Authorization", string(reqauth))
+		res.Body.Close()
 		req.Body = ioutil.NopCloser(bytes.NewReader(body.Bytes()))
 
-		res, err = l.RoundTripper.RoundTrip(req)
+		res, err = rt.RoundTrip(req)
 		if err != nil {
 			return nil, err
 		}
+		if res.StatusCode != http.StatusUnauthorized {
+			return res, err
+		}
+		resauth = authheader(res.Header.Get("Www-Authenticate"))
 	}
 
-	if res.StatusCode == 401 {
-		resauth := authheader(res.Header.Get("Www-Authenticate"))
-		if reqauth.IsBasic() && resauth.IsNegotiate() {
+	if resauth.IsNegotiate() {
 		// 401 with request:Basic and response:Negotiate
 		res.Body.Close()
 
@@ -68,7 +78,7 @@ func (l Negotiator) RoundTrip(req *http.Request) (res *http.Response, err error)
 		req.Header.Set("Authorization", "Negotiate "+base64.StdEncoding.EncodeToString(negotiateMessage))
 		req.Body = ioutil.NopCloser(bytes.NewReader(body.Bytes()))
 
-			res, err = l.RoundTripper.RoundTrip(req)
+		res, err = rt.RoundTrip(req)
 		if err != nil {
 			return nil, err
 		}
@@ -93,8 +103,7 @@ func (l Negotiator) RoundTrip(req *http.Request) (res *http.Response, err error)
 		req.Header.Set("Authorization", "Negotiate "+base64.StdEncoding.EncodeToString(authenticateMessage))
 		req.Body = ioutil.NopCloser(bytes.NewReader(body.Bytes()))
 
-			res, err = l.RoundTripper.RoundTrip(req)
-		}
+		res, err = rt.RoundTrip(req)
 	}
 
 	return res, err