codeforces-parse-script-and-gen-token.rs

use anyhow::{ensure, Context as _};
use byteorder::{BigEndian, ReadBytesExt as _};
use easy_ext::ext;
use itertools::Itertools as _;
use ress::tokens::{IdentExt as _, StringLitExt as _};
use scraper::{Html, Selector};

fn main() -> anyhow::Result<()> {
    let client = reqwest::blocking::Client::new();

    let text = client
        .get("https://codeforces.com/enter")
        .send()?
        .error_for_status()?
        .text()?;
    let html = Html::parse_document(&text);

    html.hage()?;

    Ok(())
}

#[ext]
impl Html {
    fn hage(&self) -> anyhow::Result<()> {
        use ress::tokens::{Punct, StringLit, Token};

        let script = self
            .select(&Selector::parse("script").unwrap())
            .filter(|e| e.value().attr("src").is_none())
            .flat_map(|e| e.text())
            .exactly_one()
            .ok()
            .with_context(|| "Could not find the `<script>`")?;

        let tokens = ress::tokenize(script).with_context(|| "Could not tokenize the `<script>`")?;

        let (a, b, c, cookie_attrs) = (|| -> anyhow::Result<_> {
            let (mut a, mut b, mut c, mut cookie_attrs) = (None, None, None, None);

            for i in 0..tokens.len() {
                let tokens = &tokens[i..];

                if let [Token::Ident(var_name), Token::Punct(Punct::Equal), Token::Ident(function_name), Token::Punct(Punct::OpenParen), Token::String(string_lit), Token::Punct(Punct::CloseParen), ..] =
                    tokens
                {
                    if function_name == "toNumbers" {
                        match var_name.as_str() {
                            "a" => a = Some(hex::decode(string_lit.no_quote())?),
                            "b" => b = Some(hex::decode(string_lit.no_quote())?),
                            "c" => c = Some(hex::decode(string_lit.no_quote())?),
                            _ => {}
                        }
                    }
                } else if let [Token::Ident(expr_part1), Token::Punct(Punct::Period), Token::Ident(expr_part2), Token::Punct(Punct::Equal), Token::String(string_lit1), Token::Punct(Punct::Plus), Token::Ident(function_name), Token::Punct(Punct::OpenParen), _, _, _, Token::Punct(Punct::OpenParen), _, _, _, _, _, _, _, Token::Punct(Punct::CloseParen), Token::Punct(Punct::CloseParen), Token::Punct(Punct::Plus), Token::String(string_lit2), Token::Punct(Punct::SemiColon), ..] =
                    tokens
                {
                    if expr_part1 == "document"
                        && expr_part2 == "cookie"
                        && string_lit1.no_quote() == "RCPC="
                        && function_name == "toHex"
                    {
                        cookie_attrs = Some(string_lit2.no_quote());
                    }
                }
            }

            let a = a.with_context(|| "Could not find the `var a`")?;
            let b = b.with_context(|| "Could not find the `var b`")?;
            let c = c.with_context(|| "Could not find the `var c`")?;
            let cookie_attrs =
                cookie_attrs.with_context(|| "Could not find the cookie attributes")?;

            Ok((a, b, c, cookie_attrs))
        })()
        .with_context(|| format!(
            "===Expected===\n{}======\n===Actual===\n{}\n======",
            r#"function toNumbers(d) {
  var e = [];
  d.replace(/(..)/g, function(d) {
    e.push(parseInt(d, 16))
  });
  return e
}

function toHex() {
  for (var d = [], d = 1 == arguments.length && arguments[0].constructor == Array ? arguments[0] : arguments, e = "", f = 0; f < d.length; f++) e += (16 > d[f] ? "0" : "") + d[f].toString(16);
  return e.toLowerCase()
}
var a = toNumbers("<hex value>"),
  b = toNumbers("<hex value>"),
  c = toNumbers("<hex value>");
document.cookie = "RCPC=" + toHex(slowAES.decrypt(c, 2, a, b)) + "; <cookie attributes>";
document.location.href = "https://codeforces.com/enter?f0a28=1";
"#,
            script,
        ))
        .with_context(|| "Could not extract values from the `<script>`.")?;

        dbg!((a, b, c, cookie_attrs));

        todo!();
    }
}