TUN-868: HTTP/HTTPS mismatch should have a better error message

validation/validation.go

@@ -6,7 +6,9 @@ import (
 	"net/url"
 	"strings"
 
+	"github.com/pkg/errors"
 	"golang.org/x/net/idna"
+	"net/http"
 )
 
 const defaultScheme = "http"
@@ -48,7 +50,7 @@ func ValidateHostname(hostname string) (string, error) {
 
 func ValidateUrl(originUrl string) (string, error) {
 	if originUrl == "" {
-		return "", fmt.Errorf("Url should not be empty")
+		return "", fmt.Errorf("URL should not be empty")
 	}
 
 	if net.ParseIP(originUrl) != nil {
@@ -134,3 +136,44 @@ func validateIP(scheme, host, port string) (string, error) {
 	}
 	return fmt.Sprintf("%s://%s", scheme, host), nil
 }
+
+func ValidateHTTPService(originURL string, transport http.RoundTripper) error {
+	parsedURL, err := url.Parse(originURL)
+	if err != nil {
+		return err
+	}
+
+	client := &http.Client{Transport: transport}
+
+	initialResponse, initialErr := client.Get(parsedURL.String())
+	if initialErr != nil || initialResponse.StatusCode != http.StatusOK {
+		// Attempt the same endpoint via the other protocol (http/https); maybe we have better luck?
+		oldScheme := parsedURL.Scheme
+		parsedURL.Scheme = toggleProtocol(parsedURL.Scheme)
+
+		secondResponse, _ := client.Get(parsedURL.String())
+
+		if secondResponse != nil && secondResponse.StatusCode == http.StatusOK { // Worked this time--advise the user to switch protocols
+			return errors.Errorf(
+				"%s doesn't seem to work over %s, but does seem to work over %s. Consider changing the origin URL to %s",
+				parsedURL.Hostname(),
+				oldScheme,
+				parsedURL.Scheme,
+				parsedURL,
+			)
+		}
+	}
+
+	return initialErr
+}
+
+func toggleProtocol(httpProtocol string) string {
+	switch httpProtocol {
+	case "http":
+		return "https"
+	case "https":
+		return "http"
+	default:
+		return httpProtocol
+	}
+}

validation/validation_test.go

@@ -4,7 +4,15 @@ import (
 	"fmt"
 	"testing"
 
+	"context"
+	"crypto/tls"
+	"crypto/x509"
 	"github.com/stretchr/testify/assert"
+	"net"
+	"net/http"
+	"net/http/httptest"
+	"net/url"
+	"strings"
 )
 
 func TestValidateHostname(t *testing.T) {
@@ -42,7 +50,7 @@ func TestValidateHostname(t *testing.T) {
 
 func TestValidateUrl(t *testing.T) {
 	validUrl, err := ValidateUrl("")
-	assert.Equal(t, fmt.Errorf("Url should not be empty"), err)
+	assert.Equal(t, fmt.Errorf("URL should not be empty"), err)
 	assert.Empty(t, validUrl)
 
 	validUrl, err = ValidateUrl("https://localhost:8080")
@@ -134,3 +142,102 @@ func TestValidateUrl(t *testing.T) {
 	assert.Equal(t, "https://hello.example.com:8080", validUrl)
 
 }
+
+func TestToggleProtocol(t *testing.T) {
+	assert.Equal(t, "https", toggleProtocol("http"))
+	assert.Equal(t, "http", toggleProtocol("https"))
+	assert.Equal(t, "random", toggleProtocol("random"))
+	assert.Equal(t, "", toggleProtocol(""))
+}
+
+func TestValidateHTTPService_HTTP2HTTP(t *testing.T) {
+	server, client, err := createMockServerAndClient(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(200)
+	}))
+	assert.NoError(t, err)
+	defer server.Close()
+
+	assert.Equal(t, nil, ValidateHTTPService("http://example.com/", client.Transport))
+}
+
+func TestValidateHTTPService_ServerNonOKResponse(t *testing.T) {
+	server, client, err := createMockServerAndClient(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(400)
+	}))
+	assert.NoError(t, err)
+	defer server.Close()
+
+	assert.Equal(t, nil, ValidateHTTPService("http://example.com/", client.Transport))
+}
+
+func TestValidateHTTPService_HTTPS2HTTP(t *testing.T) {
+	server, client, err := createMockServerAndClient(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(200)
+	}))
+	assert.NoError(t, err)
+	defer server.Close()
+
+	assert.Equal(t,
+		"example.com doesn't seem to work over https, but does seem to work over http. Consider changing the origin URL to http://example.com:1234/",
+		ValidateHTTPService("https://example.com:1234/", client.Transport).Error())
+}
+
+func TestValidateHTTPService_HTTPS2HTTPS(t *testing.T) {
+	server, client, err := createSecureMockServerAndClient(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(200)
+	}))
+	assert.NoError(t, err)
+	defer server.Close()
+
+	assert.Equal(t, nil, ValidateHTTPService("https://example.com/", client.Transport))
+}
+
+func TestValidateHTTPService_HTTP2HTTPS(t *testing.T) {
+	server, client, err := createSecureMockServerAndClient(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.WriteHeader(200)
+	}))
+	assert.NoError(t, err)
+	defer server.Close()
+
+	assert.Equal(t,
+		"example.com doesn't seem to work over http, but does seem to work over https. Consider changing the origin URL to https://example.com:1234/",
+		ValidateHTTPService("http://example.com:1234/", client.Transport).Error())
+}
+
+func createMockServerAndClient(handler http.Handler) (*httptest.Server, *http.Client, error) {
+	client := http.DefaultClient
+	server := httptest.NewServer(handler)
+
+	client.Transport = &http.Transport{
+		Proxy: func(req *http.Request) (*url.URL, error) {
+			return url.Parse(server.URL)
+		},
+	}
+
+	return server, client, nil
+}
+
+func createSecureMockServerAndClient(handler http.Handler) (*httptest.Server, *http.Client, error) {
+	client := http.DefaultClient
+	server := httptest.NewTLSServer(handler)
+
+	cert, err := x509.ParseCertificate(server.TLS.Certificates[0].Certificate[0])
+	if err != nil {
+		server.Close()
+		return nil, nil, err
+	}
+
+	certpool := x509.NewCertPool()
+	certpool.AddCert(cert)
+
+	client.Transport = &http.Transport{
+		DialContext: func(ctx context.Context, network, addr string) (net.Conn, error) {
+			return net.Dial("tcp", server.URL[strings.LastIndex(server.URL, "/")+1:])
+		},
+		TLSClientConfig: &tls.Config{
+			RootCAs: certpool,
+		},
+	}
+
+	return server, client, nil
+}