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I am creating a captcha just for an exercise. The creation of the captcha images seem fine. But every time I try validating the captcha challenge entered by the user, the validation is done against the next captcha. I am stuck at how to go with this. Function for creating captcha images- captcha.py

import random
import Image
import ImageFont
import ImageDraw
import ImageFilter
import JpegImagePlugin
import PngImagePlugin


def gen_captcha(text, fnt, fnt_sz, file_name, fmt='JPEG'):
fgcolor = random.randint(0,0xff0000)
bgcolor = fgcolor ^ 0xffffff
font = ImageFont.truetype(fnt,fnt_sz)
dim = font.getsize(text)
im = Image.new('RGB', (dim[0]+5,dim[1]+5), bgcolor)
d = ImageDraw.Draw(im)
x, y = im.size
r = random.randint
for num in range(100):
    d.rectangle((r(0,x),r(0,y),r(0,x),r(0,y)),fill=r(0,0xffff00))
d.text((3,3), text, font=font, fill=fgcolor)
im = im.filter(ImageFilter.EDGE_ENHANCE_MORE)
im.save(file_name)

signup function from views.py

@app.route('/signup', methods = ['GET', 'POST'])
def signup():
if g.user is not None and g.user.is_authenticated():
    return redirect(url_for('index'))

words = open('app/corncob_caps.txt').readlines()
captcha_word = words[random.randint(1,len(words))]
captcha_filename = ''.join(random.choice(string.ascii_uppercase + string.digits) for x in range(10)) + '.jpg'
captcha.gen_captcha(captcha_word.strip(), 'app/os.ttf', 25, 'app/static/' + captcha_filename + '')


form = SignUpForm(captcha_word)

if form.validate_on_submit() == False:
    return render_template('signup.html', form = form, filename = captcha_filename)
else:
    user = User(form.email.data, form.password.data)
    db.session.add(user)
    db.session.commit()
    flash('You have successfully signed up.')
    flash('You may login now.')
    return redirect(url_for('login'))

return render_template('signup.html', form = form, filename = captcha_filename)

I am passing the captcha_word to my form class. The form class is:

class SignUpForm(Form):
email = EmailField('Email Address', validators = [email()])
password = PasswordField('Password', validators = [Required('Please enter a valid password between 8 and 30 characters.'), Length(min = 8, max = 30)])
captcha = TextField('Captcha', validators = [Required('You must enter the challenge captcha.')])
submit = SubmitField('Create Account')
captcha_word = ''

def __init__(self, word, *args, **kwargs):
    Form.__init__(self, *args, **kwargs)
    self.get_word(word)

def get_word(self, word):
    self.captcha_word = word

def validate(self):
    if not Form.validate(self):
        return False
    elif self.captcha_word != self.captcha.data.upper():
        print self.captcha_word
        print self.captcha.data.upper()
        self.captcha.errors.append("Wrong captcha!")
        return False

    user = self.get_user()
    if user:
        self.email.errors.append("That email is already taken.")
        return False
    else:
        return True

def get_user(self):
    return User.query.filter_by(email = self.email.data.lower()).first()

I inserted the two print statements inside to see why the comparison was coming wrong. The first print showed the next captcha whereas the print self.captcha.data.upper() displayed the user entered data.

I am not sure, but it seems the signup route is being called twice. But I don't know how to fix this. Any ideas?

4

1 回答 1

4

如果您需要使用验证码，您可以使用Flask-WTF 中已经内置的功能，而无需重新发明轮子。

如果您确实想重新发明轮子，那么您遇到的主要问题是当用户提交表单时您正在重新创建验证码，您无法记住并引用旧值。

所以这就是它目前的工作方式：

  • 用户去登录，你生成一个验证码，然后因为他们没有提交表单，所以它显示了包含验证码图片的登录表单。
  • 用户填写表单并点击提交按钮 - 这会再次加载注册视图，创建一个新的随机验证码，然后沿着表单提交的逻辑路径向下移动，因此当您将用户验证码数据与当前验证码数据进行比较时，它不会不匹配。

因此，您缺少持久性，您第一次生成的验证码不会在任何地方保存，因此当用户提交时，您无法再参考它。因此，您需要将该验证码存储在某处。您可以简单地将该验证码字存储在用户会话中，并在需要时使用它来验证，或者也许用它的危险签名并将其作为隐藏字段存储在表单本身中？

代码示例：

这只是需要您的代码并对其进行一些调整以将值存储在会话中-未经测试，并且绝对可以改进，但应该可以：

@app.route('/signup', methods = ['GET', 'POST'])
def signup():

    if g.user is not None and g.user.is_authenticated():
        return redirect(url_for('index'))

    if request.method == 'post':
        captcha_word = session["captcha"]
    else:
        words = open('app/corncob_caps.txt').readlines()
        captcha_word = words[random.randint(1,len(words))]
        session["captcha"] = captcha_word
        captcha_filename = ''.join(random.choice(string.ascii_uppercase + string.digits) for x in range(10)) + '.jpg'
        captcha.gen_captcha(captcha_word.strip(), 'app/os.ttf', 25, 'app/static/' + captcha_filename + '')


    form = SignUpForm(captcha_word)

    if form.validate_on_submit() == False:
        return render_template('signup.html', form = form, filename = captcha_filename)
    else:
        user = User(form.email.data, form.password.data)
        db.session.add(user)
        db.session.commit()
        flash('You have successfully signed up.')
        flash('You may login now.')
        return redirect(url_for('login'))

    return render_template('signup.html', form = form, filename = captcha_filename)
于 2013-10-23T15:41:35.230 回答