objective c - iOS HTTPS requests 101

Question

NSURLConnection/CFURLConnection HTTP load failed (kCFStreamErrorDomainSSL, -9813)

Very, very frustrating! I've been pulling my hair for hours with this. I'm using a self-signed certificate on my Linode server. The port is 8000, couldn't get it to work on 443. I don't believe this is the reason though. Here's my code, it's 99% boilerplate:

NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:@"https://www.myserver.com:8000/test.json"]];
NSURLConnection *conn = [[NSURLConnection alloc] initWithRequest:request delegate:self startImmediately:YES];

At the bottom:

#pragma mark NSURLConnectionDelegate

- (BOOL)connection:(NSURLConnection *)connection canAuthenticateAgainstProtectionSpace:(NSURLProtectionSpace *)protectionSpace {
    NSLog(@"protectionSpace: %@", [protectionSpace authenticationMethod]);

    // We only know how to handle NTLM authentication.
    if([[protectionSpace authenticationMethod] isEqualToString:NSURLAuthenticationMethodNTLM])
        return YES;

    // Explicitly reject ServerTrust. This is occasionally sent by IIS.
    if([[protectionSpace authenticationMethod] isEqualToString:NSURLAuthenticationMethodServerTrust])
        return NO;

    return NO;
}

- (void)connection:(NSURLConnection *)connection didReceiveAuthenticationChallenge:(NSURLAuthenticationChallenge *)challenge {
    [[challenge sender] continueWithoutCredentialForAuthenticationChallenge:challenge];
}

- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response {
    NSLog(@"%@", response);
}

- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {
    NSLog(@"%@", data);
}

- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error {
    NSLog(@"didFailWithError");
    NSLog([NSString stringWithFormat:@"Connection failed: %@", [error description]]);
}

OMG HELP!

UPDATE

It worked with this delegate method. I'm receiving the response, but there is a problem.

- (void)connection:(NSURLConnection *)connection willSendRequestForAuthenticationChallenge:(NSURLAuthenticationChallenge *)challenge {
    [[challenge sender] useCredential:[NSURLCredential
                                       credentialWithUser:@"user"
                                       password:@"password"
                                       persistence:NSURLCredentialPersistencePermanent] forAuthenticationChallenge:challenge];

}

The "user" and "password" that I have provided are completely random and aren't checked by the server. How can I verify the credentials before accepting the connection on my server?

EDIT: I'm running a Node.js server

Answer 1

Getting the corresponding error description may help:

So, first the error domain kCFStreamErrorDomainSSL means that the error code is an SSL error code as defined in Security/SecureTransport.h:

kCFStreamErrorDomainSSL, -9813 means:

errSSLNoRootCert = -9813, /* cert chain not verified by root */

And that simply means, you have no trusted root certificate and the connection fails because of that authentication failure.

Provide a root certificate on the device for the server trust authentication and you are fine.

There are a few approaches to implement server trust authentication with self-signed certificates, the one more secure than the other.

The simplest approach requires a self-signed certificate which is stored in the bundle of the app, then retrieved and simply byte-compared. Here is an example:

Implementing server trust authentication with a self-signed certificate.

These are a must read also: Technical Note TN2232 HTTPS Server Trust Evaluation and Technical Q&A QA1360 Describing the kSecTrustResultUnspecified error.

The more preferred approach is to use a CA (Certificate Authority) which you can be yourself. That is, you create your own CA and your certificates signed with this CA.

The steps are similar:

1. Bundel the DER file of your CA's root certificate in your app.

2. Handle the server trust authentication as follows:

   1. get the authentication challenge
   2. retrieve the trust object from the challenge
   3. create a certificate object from the data in your bundle
   4. set the certificate object as an anchor to the trust object using function SecTrustSetAnchorCertificates.
   5. evaluate the trust