RustでreCAPTCHA Enterpriseを解く

[package]
name = "solvethree-example"
version = "0.1.0"
edition = "2021"

[dependencies]
reqwest = { version = "=0.13.5", features = ["json"] }
serde_json = "1"
tokio = { version = "1", features = ["macros", "rt-multi-thread", "time"] }

use std::{env, error::Error, time::{Duration, SystemTime, UNIX_EPOCH}};
use reqwest::{Client, redirect::Policy};
use serde_json::{json, Value};

#[tokio::main]
async fn main() -> Result<(), Box<dyn Error>> {
    let api = "https://api.solvethree.com/v1";
    let key = env::var("SOLVETHREE_API_KEY")?;
    let request_id = env::var("REQUEST_ID").unwrap_or_else(|_| format!("rust-{}", SystemTime::now().duration_since(UNIX_EPOCH).unwrap().as_nanos()));
    let input = json!({"site":"accounts.example.com", "action":"login", "proxy":env::var("SOLVETHREE_PROXY")?, "requestId":request_id});
    let client = Client::builder().redirect(Policy::none()).timeout(Duration::from_secs(30)).build()?;
    let mut task_id: Option<String> = None;
    let outcome = tokio::time::timeout(Duration::from_secs(180), async {
        let response = client.post(format!("{api}/tasks?waitMs=0")).bearer_auth(&key).json(&input).send().await?;
        if !response.status().is_success() { return Err(format!("API HTTP {}", response.status()).into()); }
        let mut result: Value = response.json().await?;
        let id = result["id"].as_str().ok_or("Missing task ID")?.to_owned();
        if !id.bytes().all(|b| b.is_ascii_alphanumeric() || b == b'_' || b == b'-') { return Err("Invalid task ID".into()); }
        task_id = Some(id.clone());
        loop {
            match result["status"].as_str() {
                Some("ready") => return Ok::<Value, Box<dyn Error>>(result),
                Some("failed") => return Err(format!("Task failed: {}", result["errorCode"]).into()),
                Some("pending") | Some("solving") => {},
                _ => return Err("Unexpected task status".into()),
            }
            tokio::time::sleep(Duration::from_secs(1)).await;
            let response = client.get(format!("{api}/tasks/{id}?waitMs=15000")).bearer_auth(&key).send().await?;
            if !response.status().is_success() { return Err(format!("API HTTP {}", response.status()).into()); }
            result = response.json().await?;
        }
    }).await;
    match outcome {
        Ok(Ok(result)) => {
            println!("Ready task: {}", result["id"].as_str().unwrap_or("unknown"));
            // Submit result["solution"]["token"] with returned browser headers
            // through the original proxy; do not log the solution.
            Ok(())
        },
        Ok(Err(error)) => {
            eprintln!("Recovery requestId={request_id} taskId={task_id:?}");
            Err(error)
        },
        Err(_) => {
            eprintln!("Recovery requestId={request_id} taskId={task_id:?}");
            Err("Local deadline reached; recover the existing task".into())
        }
    }
}