Solve hash cash challenges (experimental)

Cargo.lock

@@ -1404,6 +1404,7 @@ dependencies = [
  "form_urlencoded",
  "futures-core",
  "futures-util",
+ "hex",
  "hmac",
  "http",
  "httparse",
@@ -3065,6 +3066,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "dd6469f4314d5f1ffec476e05f17cc9a78bc7a27a6a857842170bdf8d6f98d2f"
 dependencies = [
  "getrandom",
+ "rand",
 ]
 
 [[package]]

core/Cargo.toml

@@ -22,6 +22,7 @@ dns-sd = { version = "0.1", optional = true }
 form_urlencoded = "1.0"
 futures-core = "0.3"
 futures-util = { version = "0.3", features = ["alloc", "bilock", "sink", "unstable"] }
+hex = "0.4"
 hmac = "0.12"
 httparse = "1.7"
 http = "0.2"
@@ -53,7 +54,7 @@ tokio-stream = "0.1"
 tokio-tungstenite = { version = "*", default-features = false, features = ["rustls-tls-native-roots"] }
 tokio-util = { version = "0.7", features = ["codec"] }
 url = "2"
-uuid = { version = "1", default-features = false, features = ["v4"] }
+uuid = { version = "1", default-features = false, features = ["fast-rng", "v4"] }
 
 [build-dependencies]
 rand = "0.8"

core/src/config.rs

@@ -2,7 +2,7 @@ use std::{fmt, path::PathBuf, str::FromStr};
 
 use url::Url;
 
-const KEYMASTER_CLIENT_ID: &str = "65b708073fc0480ea92a077233ca87bd";
+pub(crate) const KEYMASTER_CLIENT_ID: &str = "65b708073fc0480ea92a077233ca87bd";
 
 #[derive(Clone, Debug)]
 pub struct SessionConfig {

core/src/http_client.rs

@@ -15,7 +15,7 @@ use thiserror::Error;
 use url::Url;
 
 use crate::{
-    version::{FALLBACK_USER_AGENT, SPOTIFY_MOBILE_VERSION, SPOTIFY_VERSION, VERSION_STRING},
+    version::{spotify_version, FALLBACK_USER_AGENT, VERSION_STRING},
     Error,
 };
 
@@ -82,11 +82,6 @@ pub struct HttpClient {
 
 impl HttpClient {
     pub fn new(proxy_url: Option<&Url>) -> Self {
-        let spotify_version = match OS {
-            "android" | "ios" => SPOTIFY_MOBILE_VERSION.to_owned(),
-            _ => SPOTIFY_VERSION.to_string(),
-        };
-
         let spotify_platform = match OS {
             "android" => "Android/31",
             "ios" => "iOS/15.2.1",
@@ -97,7 +92,9 @@ impl HttpClient {
 
         let user_agent_str = &format!(
             "Spotify/{} {} ({})",
-            spotify_version, spotify_platform, VERSION_STRING
+            spotify_version(),
+            spotify_platform,
+            VERSION_STRING
         );
 
         let user_agent = HeaderValue::from_str(user_agent_str).unwrap_or_else(|err| {

core/src/spclient.rs

@@ -4,30 +4,37 @@ use std::{
     time::{Duration, Instant},
 };
 
+use byteorder::{BigEndian, ByteOrder};
 use bytes::Bytes;
 use futures_util::future::IntoStream;
 use http::header::HeaderValue;
 use hyper::{
     client::ResponseFuture,
-    header::{HeaderName, ACCEPT, AUTHORIZATION, CONTENT_ENCODING, CONTENT_TYPE, RANGE},
+    header::{HeaderName, ACCEPT, AUTHORIZATION, CONTENT_TYPE, RANGE},
     Body, HeaderMap, Method, Request,
 };
-use protobuf::Message;
+use protobuf::{Message, ProtobufEnum};
 use rand::Rng;
+use sha1::{Digest, Sha1};
 use thiserror::Error;
 
 use crate::{
     apresolve::SocketAddress,
     cdn_url::CdnUrl,
+    config::KEYMASTER_CLIENT_ID,
     error::ErrorKind,
     protocol::{
         canvaz::EntityCanvazRequest,
-        clienttoken_http::{ClientTokenRequest, ClientTokenRequestType, ClientTokenResponse},
+        clienttoken_http::{
+            ChallengeAnswer, ChallengeType, ClientTokenRequest, ClientTokenRequestType,
+            ClientTokenResponse, ClientTokenResponseType,
+        },
         connect::PutStateRequest,
         extended_metadata::BatchedEntityRequest,
     },
     token::Token,
-    version, Error, FileId, SpotifyId,
+    version::spotify_version,
+    Error, FileId, SpotifyId,
 };
 
 component! {
@@ -99,6 +106,42 @@ impl SpClient {
         Ok(format!("https://{}:{}", ap.0, ap.1))
     }
 
+    fn solve_hash_cash(ctx: &[u8], prefix: &[u8], length: i32, dst: &mut [u8]) {
+        let md = Sha1::digest(ctx);
+
+        let mut counter: i64 = 0;
+        let target: i64 = BigEndian::read_i64(&md[12..20]);
+
+        let suffix = loop {
+            let suffix = [(target + counter).to_be_bytes(), counter.to_be_bytes()].concat();
+
+            let mut hasher = Sha1::new();
+            hasher.update(prefix);
+            hasher.update(&suffix);
+            let md = hasher.finalize();
+
+            if BigEndian::read_i64(&md[12..20]).trailing_zeros() >= (length as u32) {
+                break suffix;
+            }
+
+            counter += 1;
+        };
+
+        dst.copy_from_slice(&suffix);
+    }
+
+    async fn client_token_request(&self, message: &dyn Message) -> Result<Bytes, Error> {
+        let body = message.write_to_bytes()?;
+
+        let request = Request::builder()
+            .method(&Method::POST)
+            .uri("https://clienttoken.spotify.com/v1/clienttoken")
+            .header(ACCEPT, HeaderValue::from_static("application/x-protobuf"))
+            .body(Body::from(body))?;
+
+        self.session().http_client().request_body(request).await
+    }
+
     pub async fn client_token(&self) -> Result<String, Error> {
         let client_token = self.lock(|inner| {
             if let Some(token) = &inner.client_token {
@@ -119,8 +162,8 @@ impl SpClient {
         message.set_request_type(ClientTokenRequestType::REQUEST_CLIENT_DATA_REQUEST);
 
         let client_data = message.mut_client_data();
-        client_data.set_client_id(self.session().client_id());
-        client_data.set_client_version(version::SEMVER.to_string());
+        client_data.set_client_id(KEYMASTER_CLIENT_ID.to_string());
+        client_data.set_client_version(spotify_version());
 
         let connectivity_data = client_data.mut_connectivity_sdk_data();
         connectivity_data.set_device_id(self.session().device_id().to_string());
@@ -169,40 +212,92 @@ impl SpClient {
             _ => {
                 let linux_data = platform_data.mut_desktop_linux();
                 linux_data.set_system_name("Linux".to_string());
-                linux_data.set_system_release("5.4.0-56-generic".to_string());
-                linux_data
-                    .set_system_version("#62-Ubuntu SMP Mon Nov 23 19:20:19 UTC 2020".to_string());
+                linux_data.set_system_release("5.15.0-46-generic".to_string());
+                linux_data.set_system_version(
+                    "#49~20.04.1-Ubuntu SMP Thu Aug 4 19:15:44 UTC 2022".to_string(),
+                );
                 linux_data.set_hardware(std::env::consts::ARCH.to_string());
             }
         }
 
-        let body = message.write_to_bytes()?;
+        let mut response = self.client_token_request(&message).await?;
 
-        let request = Request::builder()
-            .method(&Method::POST)
-            .uri("https://clienttoken.spotify.com/v1/clienttoken")
-            .header(ACCEPT, HeaderValue::from_static("application/x-protobuf"))
-            .header(CONTENT_ENCODING, HeaderValue::from_static(""))
-            .body(Body::from(body))?;
+        let token_response = loop {
+            let message = ClientTokenResponse::parse_from_bytes(&response)?;
+            match ClientTokenResponseType::from_i32(message.response_type.value()) {
+                // depending on the platform, you're either given a token immediately
+                // or are presented a hash cash challenge to solve first
+                Some(ClientTokenResponseType::RESPONSE_GRANTED_TOKEN_RESPONSE) => break message,
+                Some(ClientTokenResponseType::RESPONSE_CHALLENGES_RESPONSE) => {
+                    trace!("received a hash cash challenge");
 
-        let response = self.session().http_client().request_body(request).await?;
-        let message = ClientTokenResponse::parse_from_bytes(&response)?;
+                    let challenges = message.get_challenges().clone();
+                    let state = challenges.get_state();
+                    if let Some(challenge) = challenges.challenges.first() {
+                        let hash_cash_challenge = challenge.get_evaluate_hashcash_parameters();
 
-        let client_token = self.lock(|inner| {
-            let access_token = message.get_granted_token().get_token().to_owned();
+                        let ctx = vec![];
+                        let prefix = hex::decode(&hash_cash_challenge.prefix).map_err(|e| {
+                            Error::failed_precondition(format!(
+                                "unable to decode Hashcash challenge: {}",
+                                e
+                            ))
+                        })?;
+                        let length = hash_cash_challenge.length;
 
+                        let mut suffix = vec![0; 0x10];
+                        Self::solve_hash_cash(&ctx, &prefix, length, &mut suffix);
+
+                        // the suffix must be in uppercase
+                        let suffix = hex::encode(suffix).to_uppercase();
+
+                        let mut answer_message = ClientTokenRequest::new();
+                        answer_message.set_request_type(
+                            ClientTokenRequestType::REQUEST_CHALLENGE_ANSWERS_REQUEST,
+                        );
+
+                        let challenge_answers = answer_message.mut_challenge_answers();
+
+                        let mut challenge_answer = ChallengeAnswer::new();
+                        challenge_answer.mut_hash_cash().suffix = suffix.to_string();
+                        challenge_answer.ChallengeType = ChallengeType::CHALLENGE_HASH_CASH;
+
+                        challenge_answers.state = state.to_string();
+                        challenge_answers.answers.push(challenge_answer);
+
+                        response = self.client_token_request(&answer_message).await?;
+
+                        // we should have been granted a token now
+                        continue;
+                    } else {
+                        return Err(Error::failed_precondition("no challenges found"));
+                    }
+                }
+
+                Some(unknown) => {
+                    return Err(Error::unimplemented(format!(
+                        "unknown client token response type: {:?}",
+                        unknown
+                    )))
+                }
+                None => return Err(Error::failed_precondition("no client token response type")),
+            }
+        };
+
+        let granted_token = token_response.get_granted_token();
+        let access_token = granted_token.get_token().to_owned();
+
+        self.lock(|inner| {
             let client_token = Token {
                 access_token: access_token.clone(),
                 expires_in: Duration::from_secs(
-                    message
-                        .get_granted_token()
+                    granted_token
                         .get_refresh_after_seconds()
                         .try_into()
                         .unwrap_or(7200),
                 ),
                 token_type: "client-token".to_string(),
-                scopes: message
-                    .get_granted_token()
+                scopes: granted_token
                     .get_domains()
                     .iter()
                     .map(|d| d.domain.clone())
@@ -210,13 +305,12 @@ impl SpClient {
                 timestamp: Instant::now(),
             };
 
-            trace!("Got client token: {:?}", client_token);
-
             inner.client_token = Some(client_token);
-            access_token
         });
 
-        Ok(client_token)
+        trace!("Got client token: {:?}", client_token);
+
+        Ok(access_token)
     }
 
     pub async fn request_with_protobuf(

core/src/version.rs

@@ -24,3 +24,10 @@ pub const SPOTIFY_MOBILE_VERSION: &str = "8.6.84";
 
 /// The user agent to fall back to, if one could not be determined dynamically.
 pub const FALLBACK_USER_AGENT: &str = "Spotify/117300517 Linux/0 (librespot)";
+
+pub fn spotify_version() -> String {
+    match std::env::consts::OS {
+        "android" | "ios" => SPOTIFY_MOBILE_VERSION.to_owned(),
+        _ => SPOTIFY_VERSION.to_string(),
+    }
+}