AFNetworking and submitting html form with user validated captcha - objective-c

Question

I've trying to be able to login in a website which has an html form with a captcha. The way I've been trying to do it is fetching the html of the login form, showing the captcha to a user, who will put it in a textfield and then I'm trying to submit the form.
The error I'm always getting is invalid key code, so I'm guessing the problem is the captcha I fetch in the first instance, isn't valid for the second one... Any ideas how I could do this?
The webpage is Fanfiction, and I'm doing this as a personal proyect and see if I'm capable of exporting my list of favorites and follows.
I do this in order to show the captcha to the user.
NSURL *url = [NSURL URLWithString:#"https://www.fanfiction.net"];
self.httpClient = [[AFHTTPClient alloc] initWithBaseURL:url];
[self.httpClient getPath:#"/login.php" parameters:nil success:^(AFHTTPRequestOperation *operation, id responseObject) {
TFHpple * doc = [[TFHpple alloc] initWithHTMLData:responseObject];
NSArray * elements = [doc searchWithXPathQuery:#"//img[#id='xcaptcha']"];
TFHppleElement * element = [elements objectAtIndex:0];
[self.captchaView setImageWithURL:[NSURL URLWithString:[element objectForKey:#"src"]]];
} failure:^(AFHTTPRequestOperation *operation, NSError *error) { }];
And then, whenthe user has entered the captcha code in a textfield and pressed a UIButton, I do this
NSDictionary *params = [NSDictionary dictionaryWithObjectsAndKeys:
kFFNMail, #"email",
kFFNPass, #"password",
self.captchaField.text, #"captcha",
nil];
NSURLRequest *postRequest = [self.httpClient multipartFormRequestWithMethod:#"POST"
path:#"/login.php"
parameters:params
constructingBodyWithBlock:^(id<AFMultipartFormData> formData) { }];
/*
// I think this is the same as the one before in this case
NSMutableURLRequest *postRequest = [self.httpClient requestWithMethod:#"POST"
path:#"/login.php"
parameters:params2];
*/
AFHTTPRequestOperation *operation = [[AFHTTPRequestOperation alloc] initWithRequest:postRequest];
[operation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) {
TFHpple * doc = [[TFHpple alloc] initWithHTMLData:responseObject];
} failure:^(AFHTTPRequestOperation *operation, NSError *error) { }];
[operation start];
If is of any indication, I have this working in a ruby script like this
require 'rubygems'
require 'mechanize'
require "highline/import"
a = Mechanize.new
a.get('https://www.fanfiction.net/login.php') do |page|
images = page.search("#xcaptcha")
a.get(images.first.attributes["src"]).save "captcha.jpg"
# I read the saved image,and enter the captcha code
captcha = ask "Input captcha: "
# Submit the login form
my_page = page.form_with(:action => '/login.php') do |f|
f.email = my_mail
f.password = my_pass
f.captcha = captcha
end.click_button
# already logged!
a.get('https://www.fanfiction.net/alert/story.php') do |page|
page.links.each do |link|
text = link.text.strip
next unless text.length > 0
puts text
end
end
end

Answer 1

well, turns out I was doing everything ok, just that I had forgotten one extra parameter in the form, a hidden input which had the id of the captcha.
I just needed to capture the id at the same time that I captured the captcha image, and then send it in the form POST as an extra parameter.
Hope this helps anyone.