How to do authentication in UIWebView properly?

Question

I would like to support HTTP Basic Authentication in my UIWebView.

At the moment, I am canceling requests in

webView:shouldStartLoadWithRequest:navigationType: then handle them in my own NSURLConnectionDelegate to check for and provide credentials if needed. I then use loadData:MIMEType:textEncodingName:baseURL: to present HTML in the web view. That works fine for any URLs that are passed to the delegate.

My problem is that the delegate is never called for embedded elements, like images, JavaScript or CSS files. So if I have an HTML page which references an image which is protected with basic authentication, that image cannot be loaded properly. Additionally, webView:didFinishLoad: is never called, because the web view could not fully load the page.

I have checked that case with Terra, a third-party browser available on the App Store, and it can fully cope with that situation. I think it would be possible to solve this by providing my own NSURLProtocol, but that seems too complicated. What am I missing?

Solution 1

Try to use sharedCredentialStorage for all domains you need to authenticate.

Here is working sample for UIWebView it was tested against Windows IIS having only BasicAuthentication enabled

This is how to add your site credentials:

NSString* login = @"MYDOMAIN\\myname";
NSURLCredential *credential = [NSURLCredential credentialWithUser:login
                                                         password:@"mypassword"
                                                      persistence:NSURLCredentialPersistenceForSession];

NSURLProtectionSpace *protectionSpace = [[NSURLProtectionSpace alloc]
                                         initWithHost:@"myhost"
                                                 port:80
                                             protocol:@"http"
                                                realm:@"myhost" // check your web site settigns or log messages of didReceiveAuthenticationChallenge
                                 authenticationMethod:NSURLAuthenticationMethodDefault];

[[NSURLCredentialStorage sharedCredentialStorage] setDefaultCredential:credential
                                                    forProtectionSpace:protectionSpace];
[protectionSpace release];

Edit: same code in Swift 4

let login = "MYDOMAIN\\myname"
let credential = URLCredential(user:login, password:"mypassword", persistence:.forSession)
let protectionSpace = URLProtectionSpace(host:"myhost", port:80, protocol:"http", realm:"myhost", authenticationMethod:NSURLAuthenticationMethodDefault)
URLCredentialStorage.shared.setDefaultCredential(credential, for:protectionSpace)

Your webView is supposed to work now, if it does not work use next code to debug, especially check log messages of didReceiveAuthenticationChallenge.

    #import "TheSplitAppDelegate.h"
    #import "RootViewController.h"

    @implementation TheSplitAppDelegate

    @synthesize window = _window;
    @synthesize splitViewController = _splitViewController;
    @synthesize rootViewController = _rootViewController;
    @synthesize detailViewController = _detailViewController;

    - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
    {
        // Override point for customization after application launch.
        // Add the split view controller's view to the window and display.
        self.window.rootViewController = self.splitViewController;
        [self.window makeKeyAndVisible];

        NSLog(@"CONNECTION: Add credentials");

        NSString* login = @"MYDOMAIN\\myname";
        NSURLCredential *credential = [NSURLCredential credentialWithUser:login
                                                                 password:@"mypassword"
                                                              persistence:NSURLCredentialPersistenceForSession];

        NSURLProtectionSpace *protectionSpace = [[NSURLProtectionSpace alloc]
                                                 initWithHost:@"myhost"
                                                 port:80
                                                 protocol:@"http"
                                                 realm:@"myhost" // check your web site settigns or log messages of didReceiveAuthenticationChallenge
                                                 authenticationMethod:NSURLAuthenticationMethodDefault];


        [[NSURLCredentialStorage sharedCredentialStorage] setDefaultCredential:credential forProtectionSpace:protectionSpace];
        [protectionSpace release];    

        NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:@"http://myhost/index.html"]
                                                               cachePolicy:NSURLRequestReloadIgnoringCacheData
                                                           timeoutInterval:12
                                        ];

        NSLog(@"CONNECTION: Run request");
        [[NSURLConnection alloc] initWithRequest:request delegate:self];

        return YES;
    }

    - (void)applicationWillResignActive:(UIApplication *)application
    {

    }

    - (void)applicationDidEnterBackground:(UIApplication *)application
    {

    }

    - (void)applicationWillEnterForeground:(UIApplication *)application
    {

    }

    - (void)applicationDidBecomeActive:(UIApplication *)application
    {

    }

    - (void)applicationWillTerminate:(UIApplication *)application
    {

    }

    - (void)dealloc
    {
        [_window release];
        [_splitViewController release];
        [_rootViewController release];
        [_detailViewController release];
        [super dealloc];
    }

    - (void)connection:(NSURLConnection *)connection didReceiveAuthenticationChallenge:(NSURLAuthenticationChallenge *)challenge;
    {
        NSLog(@"CONNECTION: got auth challange");
        NSString* message = [NSString stringWithFormat:@"CONNECTION: cred cout = %i", [[[NSURLCredentialStorage sharedCredentialStorage] allCredentials] count]];
        NSLog(message);
        NSLog([connection description]);

        NSLog([NSString stringWithFormat:@"CONNECTION: host = %@", [[challenge protectionSpace] host]]);
        NSLog([NSString stringWithFormat:@"CONNECTION: port = %i", [[challenge protectionSpace] port]]);
        NSLog([NSString stringWithFormat:@"CONNECTION: protocol = %@", [[challenge protectionSpace] protocol]]);
        NSLog([NSString stringWithFormat:@"CONNECTION: realm = %@", [[challenge protectionSpace] realm]]);
        NSLog([NSString stringWithFormat:@"CONNECTION: authenticationMethod = %@", [[challenge protectionSpace] authenticationMethod]]);
    }

    - (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error{
        // release the connection, and the data object
        [connection release];

        // inform the user
        NSLog(@"CONNECTION: failed! Error - %@ %@",
              [error localizedDescription],
              [[error userInfo] objectForKey:NSURLErrorFailingURLStringErrorKey]);
    } 

    - (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response;
    {
        NSLog(@"CONNECTION: received response via nsurlconnection");
    }

    - (BOOL)connectionShouldUseCredentialStorage:(NSURLConnection *)connection;
    {
        NSLog(@"CONNECTION: USE!");
        return YES;
    }


    @end

The final solution for WebView authentication was based on custom protocol implementation. All protocols registered as a stack, so if you redefine HTTP protocol it would intercept all requests coming from webView, so you have to check attributes assotiated with incoming request and repack it into new request and send it again via your own connection. Since you are in stack, your request immidiatly comes to you again and you have to ignore it. So it goes down protocol stack to real HTTP protocol implementation, since your request is not athenticated you'll get authenticaiton request. And after authenticaiton you'll get a real response from server, so you repack response and reply to original request received from webView and that's it.

Don;t try to create new requests or responses bodies, you have to just resend them. The final code would be aproximetly 30-40 lines of code and it is quite simple, but requires a lot of debuging and tetsing.

Unfortunatlly I cannot provide code here, since I am assigned to different project already, I just wanted to say that my post is wrong way, it stucks when user changes password.

Solution 2

The secret to HTTP basic authentication using cocoa is knowing NSURL and the related classes.

• NSURL
• NSURLRequest/NSMutableURLRequest
• NSURLConnection
• NSURLCredential
• NSURLCredentialStorage
• NSURLProtectionSpace
• UIWebView/WebView/NIWebController etc.

The real magic comes from NSURLConnection. In the words of the devDocs, "An NSURLConnection object provides support to perform the loading of a URL request." If you want to load some a URL in the background without displaying it you would use NSURLConnection. The real power of the NSURLConnection is in the method

+ (NSURLConnection *)connectionWithRequest:(NSURLRequest *)request delegate:(id < NSURLConnectionDelegate >)delegate

The NSURLConnectionDelegate protocol has methods for responding to successful connections, fatal errors, and authentication challenges. If you are trying to access data Protected by HTTP basic authentication this is how Cocoa does it. At this point an example should bring some clarity.

//basic HTTP authentication
NSURL *url = [NSURL URLWithString: urlString];
NSMutableURLRequest *request;
request = [NSMutableURLRequest requestWithURL:url
                              cachePolicy:NSURLRequestReloadIgnoringCacheData
                          timeoutInterval:12];
[self.webView openRequest:request];
(void)[NSURLConnection connectionWithRequest:request delegate:self];

This creates a URL. From the URL a URLRequest is created. The URLRequest is then loaded in the web view. The Request is also used to make a URLConnection. We don't really use the connection, but we need to receive notifications about authentication so we set the delegate. There are only two methods we need from the delegate.

- (void)connection:(NSURLConnection *)connection didReceiveAuthenticationChallenge:(NSURLAuthenticationChallenge *)challenge;
{  
    NSURLCredential * cred = [NSURLCredential credentialWithUser:@"username"
                                                    password:@"password"
                                                 persistence:NSURLCredentialPersistenceForSession];
[[NSURLCredentialStorage sharedCredentialStorage]setCredential:cred forProtectionSpace:[challenge protectionSpace]];

}

- (BOOL)connectionShouldUseCredentialStorage:(NSURLConnection *)connection;
{
    return YES;
}

Whenever there is an authentication challenge a credential is added to the credential storage. You also tell the connection to use the credential storage.

Solution 3

I've just implemented this by setting basic auth credentials using an NSMutableURLRequest for the UIWebView. This also avoids the round trip incurred when implementing sharedCredentialStorage (of course there are tradeoffs involved).

Solution:

    NSString *url = @"http://www.my-url-which-requires-basic-auth.io"
    NSString *authStr = [NSString stringWithFormat:@"%@:%@", username, password];
    NSData *authData = [authStr dataUsingEncoding:NSASCIIStringEncoding];
    NSString *authValue = [NSString stringWithFormat:@"Basic %@", [authData base64EncodedString]];
    NSMutableURLRequest *mutableRequest = [[NSMutableURLRequest alloc] initWithURL:[NSURL URLWithString:url]];
    [mutableRequest setValue:authValue forHTTPHeaderField:@"Authorization"];
    NSURLRequest *request = [mutableRequest copy];
    NSURLRequest *request = [NSURLRequest basicAuthHTTPURLRequestForUrl:url];
    [self.webView loadRequest:request];

You can grab the NSData+Base64 category which implements the base64EncodedString for NSData from Matt Gallagher's page (it was at the bottom of the blog post when I downloaded it)

Solution 4

For TKAURLProtocolPro [http://kadao.dir.bg/cocoa.htm] For SVWebViewController [https://github.com/samvermette/SVWebViewController]

View more solutions

Comments

[Max MacLeod]

does this happen automatically? Once authenticated against a host, it seems that it's not necessary to re-authenticate on subsequent requests.

[gstroup]

I'm seeing the same behavior as Max. Once authenticated, I'm not being challenged to re-authenticate again. Something is being stored in my iOS simulator session I guess? I tried resetting the simulator, but still not being challenged. Strange.

[Shoe]

"Moderator killed post important to me, I kill posts important to him. This post cost me 4 weeks of research. So have a good day". I'm sorry to announce to you that your original answer is stored in the post history and is going to be retrieved now. Thanks for the attention.

[NLemay]

Just a question : I see that you are adding the credentials in sharedCredentialStorage when you get the didReceiveAuthenticationChallenge event. But is it a good practice to reset the credentials everytime you get this event? Just asking, I'm trying to figure out how sharedCredentialStorage works.

[Andrew Hoos]

It probably is not the best solution, but it was functional and I never went back to clean it up. If the password is not going to change then you can probable put it outside of the delegate call and only do it once, if the credential is going to change it might be good to look up the current username password when the challenge is received.

[Red Nightingale]

Just thought I'd add that you no longer need the NSData+Base64 category as that functionality is included in the standard NSData implementation now (slightly different method signature though)

[NSTJ]

Indeed - check out the Apple docs for Base64 encoding here

[matteok]

In the end you define a new url request [NSURLRequest basicAuthHTTPURLRequestForUrl:url]; How do the previous definitions even influence that request?