POST request iOS: what's happening under the hood? - ios

Question

I'm facing a really strange issue and I hope somebody can help me understand where is the problem on which I'm stuck since three days ago.
In simple I make a NSMutableRequest to a simple endpoint where I send (using POST) a json and I'm supposed to receive a response 0 or 1.
The code works the first time the app is run on the device, but somehow it does not work anymore the following times.
To explain myself better, if I uninstall and reinstall the app every time, I get the correct response, but if I run the code twice the second time I get something like [CSRF verification failed] from the endpoint. This error means that I'm not sending the correct format ( or I'm sending something strange).
My question is: how is that possible? Is it possible that I'm sending something else?
The endpoint works correctly because with the android version I don't have any problems...
The code is the following, hope somebody can explain me what is happening under the hood and how I can manage to solve this problem.
NSString *mail = [profile valueForKey:#"email"];
NSString *provider = [profile valueForKey:#"provider"];
// making a GET request to endpoint
NSString *baseUrl = ENDPOINT_URL;
NSString *targetUrl = [NSString stringWithFormat:#"%#", baseUrl];
NSMutableURLRequest *request = [[NSMutableURLRequest alloc] init];
[request setHTTPMethod:#"POST"];
[request addValue:#"application/json" forHTTPHeaderField:#"Content-Type"];
[request addValue:#"application/json" forHTTPHeaderField:#"Accept"];
NSString *body = [NSString stringWithFormat:#"{\"mail\":\"%#\", \"provider\":\"%#\"}",mail,provider];
NSData *postData=[body dataUsingEncoding:NSUTF8StringEncoding];
[request setHTTPBody:postData];
[request setURL:[NSURL URLWithString:targetUrl]];
[request setCachePolicy:NSURLRequestReloadIgnoringLocalCacheData];
[[[NSURLSession sharedSession] dataTaskWithRequest:request completionHandler:
^(NSData * _Nullable data,
NSURLResponse * _Nullable response,
NSError * _Nullable error) {
if (data){
NSString *myString = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
NSLog(#"Data received: %#", myString);
if ([myString isEqualToString:#"[\"CSRF validation failed\"]"]){
NSLog(#"ENDPOINT ERROR");
dispatch_async(dispatch_get_main_queue(), ^{
[(AppDelegate *)[[UIApplication sharedApplication] delegate] loginAborted];});
} else {
NSDictionary* json = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:&error];
NSLog(#"Data received: %#", json);
NSNumber *value = [NSNumber numberWithInt:[[json objectForKey:#"profile_exists"] intValue]];
if ([value intValue] == 1){
//Profile exists.
NSLog(#"Profile exists.");
[self silentLogin:profile];
} else if ([value intValue] == 0) {
//Profile does not exists.
NSLog(#"Profile does not exist.");
[self silentRegistration:profile];
}
else {
//Error.
NSLog(#"Error in ENDPOINT VALUE");
dispatch_async(dispatch_get_main_queue(), ^{
[(AppDelegate *)[[UIApplication sharedApplication] delegate] loginAborted];});
}
NSLog(#"%#",json);
}
} else {
NSLog(#"No Data received");
dispatch_async(dispatch_get_main_queue(), ^{
[(AppDelegate *)[[UIApplication sharedApplication] delegate] loginAborted];});
}
}] resume];

Answer 1

I was able to solve the problem deleting the cookies every time I make a request. It seems that these cookies are re sent every time.
+ (void)clearCookiesForURL: (NSString *)url {
NSHTTPCookieStorage *cookieStorage = [NSHTTPCookieStorage sharedHTTPCookieStorage];
NSArray *cookies = [cookieStorage cookiesForURL:[NSURL URLWithString:url]];
for (NSHTTPCookie *cookie in cookies) {
NSLog(#"Deleting cookie for domain: %#", [cookie domain]);
[cookieStorage deleteCookie:cookie];
}
}