solve ui_metrics challenge during login

[JulienMaille]

Thanks a lot for your repository and the port of Go implementation of X-Twitter-Active-User header generator.
I noticed that during login flow, there's another challenge related to /i/js_inst?c_name=ui_metrics
The same genius wrote about this: https://github.com/obfio/twitter-ui_mentrics
Have you had time to give it a look? That may help reduce DenyLoginSubtask issues, what do you think?

[iSarabjitDhiman]

Hi @JulienMaille
Yes I checked this one a while ago. But this implementation is not stable, it may break anytime I believe. I was looking for a permanent solution, thats why I kind of left it. Though I have implemented it on my side for personal use, but I used headless mode of selenium. I will implement some functionality to solve ui_metrics soon, just looking for a better solution. If I don't find one, I will surely borrow this one.

[JulienMaille]

Hi, what have you found unstable about it? I ported to code to python and could verify it generates the expected result. Which part of the implementation do you dislike?

[iSarabjitDhiman]

No, I mean yeah the code works seamlessly. But I was looking for a robust solution rather than using regex to replace parts of JavaScript code with python native syntax. I would prefer writing the whole thing in python. Of course we need regex for some part, but I would avoid it as much I can.
But again, I am more than happy to implement the same approach if I don't find any other solution.

Hopefully I will fix it by the end of this month (in a week).

[JulienMaille]

Here is what I came up with

import re
import os
import json
from datetime import datetime, timedelta

function_regex = re.compile(r'function\s?[^\.][\w|,|\s|-|_|\$]*.+?\{([^\.][\s|\S]*(?=\}))')
init_nums_regex = re.compile(r'var [A-Za-z0-9]{64}=[0-9]+')
basic_math_regex = re.compile(r'[a-z0-9]{64}=(~|\^|\||&|[A-Za-z0-9]{64})')
func_ending_regex = re.compile(r'}\([a-z0-9]{64},[a-z0-9]{64},[a-z0-9]{64}\)')


def unix_milli_day(timestamp):
    # Convert milliseconds to a timedelta
    delta = timedelta(milliseconds=timestamp)

    # Calculate the UTC datetime by subtracting the delta from the Unix epoch
    epoch = datetime(1970, 1, 1)
    return (epoch + delta).day

def math_xor(a, b, c):
    return (b ^ a) | (c ^ b)

def math_right_shift(a, b, c):
    num = 0
    for i in range(8):
        if (a & 1) == 0:
            num += a
        if (b & 1) == 0:
            num += b
        if (c & 1) == 0:
            num += c
        a >>= 1
        b >>= 1
        c >>= 1
    return num % 256

def solve_ui_metrics(code) -> dict:

    matches = function_regex.findall(code)
    matches = function_regex.findall(matches[0])
    matches = function_regex.findall(matches[0])
    script = matches[0]
    operations = script.split(";")
    solution = {}

    inside_right_shift_func = False
    right_shift_func_key = ""
    inside_math_xor_func = False
    math_xor_func_key = ""

    for op in operations:
        # get initial numbers
        if init_nums_regex.search(op):
            parts = init_nums_regex.search(op).group().split("=")
            value = int(parts[1])
            solution[parts[0][4:]] = value
            continue
        
        # basic math, like xxx ^ xxx, ~xxx, etc.
        if basic_math_regex.search(op) and "new Date" not in op:
            sign_change = False
            math_done = False
            
            # handle ~, which changes the sign
            if "~" in op:
                # handle rather it's a `~(xxx ^ xxx)` op or not.
                if "(" in op:
                    # trim off `~(` and `)`
                    tmp = op.split("=")
                    new_part = tmp[1][2:-1]
                    op = f"{tmp[0]}={new_part}"
                else:
                    # trim off just `~`
                    tmp = op.split("=")
                    new_part = tmp[1][1:]
                    op = f"{tmp[0]}={new_part}"
                sign_change = True
            
            parts = op.split("=")
            # handle all the different operations
            if "^" in parts[1]:
                tmp = parts[1].split("^")
                solution[parts[0]] = solution[tmp[0]] ^ solution[tmp[1]]
                math_done = True
            if "|" in parts[1]:
                tmp = parts[1].split("|")
                solution[parts[0]] = solution[tmp[0]] | solution[tmp[1]]
                math_done = True
            if "&" in parts[1]:
                tmp = parts[1].split("&")
                solution[parts[0]] = solution[tmp[0]] & solution[tmp[1]]
                math_done = True
            
            if sign_change:
                if math_done:
                    solution[parts[0]] = -(solution[parts[0]] + 1)
                else:
                    solution[parts[0]] = -(solution[parts[1]] + 1)
        
        if "new Date" in op:
            parts = op.split("=")
            op_parts = parts[1].split("^")
            solution[parts[0]] = solution[op_parts[0]] ^ unix_milli_day(solution[op_parts[1].split("*")[0].split("(")[1]] * 10000000000)
        
        # detect the rightShiftFunc starting
        if "document.createElement('div')" in op and not inside_right_shift_func:
            inside_right_shift_func = True
            right_shift_func_key = op.split("=function")[0]
        
        # detect the rightShiftFunc ending
        if func_ending_regex.search(op) and inside_right_shift_func:
            inside_right_shift_func = False
            in_params = op[2:-1].split(",")
            solution[right_shift_func_key] = math_right_shift(solution[in_params[0]], solution[in_params[1]], solution[in_params[2]])
            right_shift_func_key = ""
        
        # detect the mathXORFunc starting
        if "function(){return this." in op and not inside_math_xor_func:
            inside_math_xor_func = True
            math_xor_func_key = op.split("=")[0]
        
        # detect the mathXORFunc ending
        if func_ending_regex.search(op) and inside_math_xor_func:
            inside_math_xor_func = False
            in_params = op[2:-1].split(",")
            solution[math_xor_func_key] = math_xor(solution[in_params[0]], solution[in_params[1]], solution[in_params[2]])
            math_xor_func_key = ""
        
        if op.startswith("return {'rf"):
            in_params = op.split(",")[-1].split(":")
            solution[in_params[0].strip("'")] = in_params[1].strip("'")
            solution = {'rf': solution}
            break

    return str(solution).replace('\'', '\\"')


if __name__ == "__main__":
    # load sample file
    with open("./sample.js", "r") as f:
        code = f.read()
        solution = solve_ui_metrics(code)
        print(solution)

[iSarabjitDhiman]

Thanks for sharing.
Yes it's as same as the one written in Go. How long has this one in working condition? Did you ever had to modify or fix it? Just wondering when did u write it, how long has it been?

[JulienMaille]

It's fresh from yesteraday

[iSarabjitDhiman]

Ok thanks. I will find a solution and implement it soon.