changed password prompt logic and OAuth2 prompt on Windows

cmd/kopia/config.go

@@ -2,7 +2,6 @@
 
 import (
 	"encoding/hex"
-	"errors"
 	"fmt"
 	"io/ioutil"
 	"log"
@@ -112,8 +111,6 @@ func openVaultSpecifiedByFlag() (*vault.Vault, error) {
 	return vault.Open(storage, creds)
 }
 
-var errPasswordTooShort = errors.New("password too short")
-
 func getVaultCredentials(isNew bool) (vault.Credentials, error) {
 	if *key != "" {
 		k, err := hex.DecodeString(*key)
@@ -148,11 +145,6 @@ func getVaultCredentials(isNew bool) (vault.Credentials, error) {
 	if isNew {
 		for {
 			p1, err := askPass("Enter password to create new vault: ")
-			if err == errPasswordTooShort {
-				fmt.Printf("Password too short, must be at least %v characters, you entered %v. Try again.", vault.MinPasswordLength, len(p1))
-				fmt.Println()
-				continue
-			}
 			if err != nil {
 				return nil, err
 			}
@@ -177,16 +169,23 @@ func getVaultCredentials(isNew bool) (vault.Credentials, error) {
 }
 
 func askPass(prompt string) (string, error) {
-	b, err := speakeasy.Ask(prompt)
-	if err != nil {
-		return "", err
+	for {
+		b, err := speakeasy.Ask(prompt)
+		if err != nil {
+			return "", err
+		}
+
+		p := string(b)
+
+		if len(p) == 0 {
+			continue
+		}
+
+		if len(p) >= vault.MinPasswordLength {
+			return p, nil
+		}
+
+		fmt.Printf("Password too short, must be at least %v characters, you entered %v. Try again.", vault.MinPasswordLength, len(p))
+		fmt.Println()
 	}
-
-	p := string(b)
-
-	if len(p) < vault.MinPasswordLength {
-		return p, errPasswordTooShort
-	}
-
-	return p, nil
 }

storage/gcs/gcs.go

@@ -7,9 +7,13 @@
 	"io/ioutil"
 	"log"
 	"net/http"
+	"net/http/httptest"
 	"os"
+	"runtime"
 	"time"
 
+	"github.com/skratchdot/open-golang/open"
+
 	"github.com/kopia/kopia/storage"
 
 	"golang.org/x/net/context"
@@ -296,6 +300,61 @@ func writeTokenToFile(filePath string, token *oauth2.Token) error {
 }
 
 func tokenFromWeb(ctx context.Context, config *oauth2.Config) (*oauth2.Token, error) {
+	if runtime.GOOS == "windows" {
+		return tokenFromWebLocalServer(ctx, config)
+	}
+
+	// On non-SSH Unix, that has X11 configured use local web server.
+	if os.Getenv("DISPLAY") != "" && os.Getenv("SSH_CLIENT") == "" {
+		return tokenFromWebLocalServer(ctx, config)
+	}
+
+	// Otherwise fall back to asking user to manually copy/paste the code.
+	return tokenFromWebManual(ctx, config)
+}
+
+func tokenFromWebLocalServer(ctx context.Context, config *oauth2.Config) (*oauth2.Token, error) {
+	ch := make(chan string)
+	randState := fmt.Sprintf("st%d", time.Now().UnixNano())
+	ts := httptest.NewServer(http.HandlerFunc(func(rw http.ResponseWriter, req *http.Request) {
+		if req.URL.Path == "/favicon.ico" {
+			http.Error(rw, "", 404)
+			return
+		}
+		if req.FormValue("state") != randState {
+			log.Printf("State doesn't match: req = %#v", req)
+			http.Error(rw, "", 500)
+			return
+		}
+		if code := req.FormValue("code"); code != "" {
+			fmt.Fprintf(rw, "<h1>Success</h1>Authorized.")
+			rw.(http.Flusher).Flush()
+			ch <- code
+			return
+		}
+		log.Printf("no code")
+		http.Error(rw, "", 500)
+	}))
+	defer ts.Close()
+
+	config.RedirectURL = ts.URL
+	authURL := config.AuthCodeURL(randState)
+	go open.Start(authURL)
+	fmt.Println("Opening URL in web browser to get OAuth2 authorization token:")
+	fmt.Println()
+	fmt.Println("  ", authURL)
+	fmt.Println()
+	code := <-ch
+
+	token, err := config.Exchange(ctx, code)
+	if err != nil {
+		return nil, fmt.Errorf("token exchange error: %v", err)
+	}
+
+	return token, nil
+}
+
+func tokenFromWebManual(ctx context.Context, config *oauth2.Config) (*oauth2.Token, error) {
 	config.RedirectURL = "urn:ietf:wg:oauth:2.0:oob"
 	authURL := config.AuthCodeURL("")
 	var code string