微信回调域名校验失败

from flask import Flask, request

app = Flask(__name__)

@app.route('/wechat', methods=['GET'])
def wechat_verify():
    token = 'your_wechat_token'
    signature = request.args.get('signature')
    timestamp = request.args.get('timestamp')
    nonce = request.args.get('nonce')
    echostr = request.args.get('echostr')

    # 验证签名
    if check_signature(token, signature, timestamp, nonce):
        return echostr
    else:
        return 'Invalid request'

def check_signature(token, signature, timestamp, nonce):
    import hashlib
    tmp_list = [token, timestamp, nonce]
    tmp_list.sort()
    tmp_str = ''.join(tmp_list)
    tmp_str = hashlib.sha1(tmp_str.encode('utf-8')).hexdigest()
    return tmp_str == signature

if __name__ == '__main__':
    app.run(host='0.0.0.0', port=80)