Panel: Yggdrasil auth server (authlib-injector), skins and capes

- Yggdrasil API per the authlib-injector spec: metadata with signing key
  and skin domains, authenticate/refresh/validate/invalidate/signout,
  join/hasJoined, profile lookup, texture upload, and the minecraftservices
  endpoints (chat certificates, publickeys, attributes, blocklist)
- 4096-bit signing key generated once into the data volume; textures and
  chat certificates signed SHA1withRSA (verified with Java's own crypto)
- Skins/capes stored content-addressed after validation and re-encoding;
  cape library with public/group/private visibility; head avatars API
- Launcher login returns a game session; launcher sessions recorded for
  launcher-only servers; authlib-injector download mirror
- Schema v2: player UUIDs (offline UUID backfilled), skins, capes, tokens,
  sessions, chat keys, game server tables
- Remove Microsoft sign-in from the engine and panel

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011ARcGWxLx21FwXJ3yfGriS

crates/core/src/authlib.rs

@@ -0,0 +1,130 @@
+//! authlib-injector: a small Java agent that points the game's
+//! authentication (sessions, skins, profile signatures) at the panel's
+//! Yggdrasil server instead of Mojang's.
+//!
+//! The launcher fetches it from the panel's mirror first and falls back to
+//! the official download, verifying the SHA-256 either way.
+
+use crate::http::{self, Download};
+use crate::paths::Layout;
+use anyhow::{anyhow, bail, Context, Result};
+use base64::Engine;
+use serde::{Deserialize, Serialize};
+use sha2::{Digest, Sha256};
+use std::path::{Path, PathBuf};
+
+pub const OFFICIAL_LATEST: &str = "https://authlib-injector.yushi.moe/artifact/latest.json";
+
+/// Shape of `latest.json` (the panel mirror uses the same format).
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct Artifact {
+    pub build_number: u64,
+    pub version: String,
+    pub download_url: String,
+    pub checksums: Checksums,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct Checksums {
+    pub sha256: String,
+}
+
+pub fn sha256_file(path: &Path) -> Result<String> {
+    let bytes = std::fs::read(path)?;
+    Ok(hex::encode(Sha256::digest(&bytes)))
+}
+
+fn cache_dir(layout: &Layout) -> PathBuf {
+    layout.cache().join("authlib-injector")
+}
+
+/// Newest jar already on disk (used when offline).
+fn newest_cached(layout: &Layout) -> Option<PathBuf> {
+    std::fs::read_dir(cache_dir(layout))
+        .ok()?
+        .filter_map(|e| e.ok())
+        .map(|e| e.path())
+        .filter(|p| p.extension().is_some_and(|x| x == "jar"))
+        .max_by_key(|p| std::fs::metadata(p).and_then(|m| m.modified()).ok())
+}
+
+async fn from_source(client: &reqwest::Client, layout: &Layout, index_url: &str, base: Option<&str>) -> Result<PathBuf> {
+    let artifact: Artifact = http::get_json(client, index_url).await?;
+    let url = match base {
+        Some(b) => crate::sync::resolve_url(b, &artifact.download_url),
+        None => artifact.download_url.clone(),
+    };
+    let dest = cache_dir(layout).join(format!("authlib-injector-{}.jar", artifact.version));
+    let expected = artifact.checksums.sha256.to_ascii_lowercase();
+    if dest.exists() && sha256_file(&dest)? == expected {
+        return Ok(dest);
+    }
+    http::download_one(client, &Download::new(url, dest.clone(), None, None), &|_| {}).await?;
+    let got = sha256_file(&dest)?;
+    if got != expected {
+        std::fs::remove_file(&dest).ok();
+        bail!("authlib-injector checksum mismatch (expected {expected}, got {got})");
+    }
+    Ok(dest)
+}
+
+/// Make sure authlib-injector is available locally and return its path.
+pub async fn ensure(client: &reqwest::Client, layout: &Layout, panel_base: Option<&str>) -> Result<PathBuf> {
+    let mut errors = Vec::new();
+    if let Some(base) = panel_base.filter(|b| !b.is_empty()) {
+        let index = format!("{}/api/v1/launcher/authlib-injector.json", base.trim_end_matches('/'));
+        match from_source(client, layout, &index, Some(base)).await {
+            Ok(p) => return Ok(p),
+            Err(e) => errors.push(format!("panel mirror: {e:#}")),
+        }
+    }
+    match from_source(client, layout, OFFICIAL_LATEST, None).await {
+        Ok(p) => return Ok(p),
+        Err(e) => errors.push(format!("official download: {e:#}")),
+    }
+    if let Some(cached) = newest_cached(layout) {
+        tracing::warn!("using cached authlib-injector ({})", errors.join("; "));
+        return Ok(cached);
+    }
+    Err(anyhow!("couldn't download authlib-injector: {}", errors.join("; ")))
+}
+
+/// Fetch the Yggdrasil metadata so it can be handed to the agent up front
+/// (saves the game a network round-trip at startup).
+pub async fn prefetch_metadata(client: &reqwest::Client, api_url: &str) -> Result<String> {
+    let resp = client.get(api_url).send().await?.error_for_status().context("fetching auth server metadata")?;
+    let bytes = resp.bytes().await?;
+    // Must be valid JSON, or the agent would refuse to start.
+    serde_json::from_slice::<serde_json::Value>(&bytes).context("auth server metadata isn't JSON")?;
+    Ok(base64::engine::general_purpose::STANDARD.encode(&bytes))
+}
+
+/// JVM arguments that load the agent. They must come before the main class.
+pub fn jvm_args(jar: &Path, api_url: &str, prefetched: Option<&str>) -> Vec<String> {
+    let mut args = vec![format!("-javaagent:{}={}", jar.display(), api_url)];
+    if let Some(p) = prefetched {
+        args.push(format!("-Dauthlibinjector.yggdrasil.prefetched={p}"));
+    }
+    args
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn builds_agent_args() {
+        let args = jvm_args(Path::new("/c/ai.jar"), "https://panel.example/api/yggdrasil", Some("e30="));
+        assert_eq!(args[0], "-javaagent:/c/ai.jar=https://panel.example/api/yggdrasil");
+        assert_eq!(args[1], "-Dauthlibinjector.yggdrasil.prefetched=e30=");
+    }
+
+    #[test]
+    fn parses_latest_json() {
+        let a: Artifact = serde_json::from_str(
+            r#"{"build_number":53,"version":"1.2.5","release_time":"x","download_url":"https://x/a.jar","checksums":{"sha256":"ab"}}"#,
+        )
+        .unwrap();
+        assert_eq!(a.version, "1.2.5");
+    }
+}

crates/core/src/launch.rs

@@ -27,14 +27,15 @@ pub struct Auth {
     /// Dashed or undashed UUID.
     pub uuid: String,
     pub access_token: String,
-    /// "msa" for Microsoft accounts, "legacy" for offline.
+    /// "mojang" for panel (Yggdrasil) accounts, "legacy" for offline.
     pub user_type: String,
-    pub xuid: Option<String>,
 }
 
 #[derive(Debug, Clone)]
 pub struct LaunchOptions {
     pub auth: Auth,
+    /// JVM arguments that must come first (the authlib-injector agent).
+    pub agent_args: Vec<String>,
     pub game_dir: PathBuf,
     pub memory_min_mb: u32,
     pub memory_max_mb: u32,
@@ -187,7 +188,7 @@ pub fn build(installed: &Installed, layout: &Layout, opts: &LaunchOptions) -> Co
     vars.insert("auth_access_token", opts.auth.access_token.clone());
     vars.insert("auth_session", format!("token:{}:{}", opts.auth.access_token, uuid));
     vars.insert("clientid", String::new());
-    vars.insert("auth_xuid", opts.auth.xuid.clone().unwrap_or_default());
+    vars.insert("auth_xuid", String::new());
     vars.insert("user_type", opts.auth.user_type.clone());
     vars.insert("user_properties", "{}".into());
     vars.insert("version_type", opts.version_label.clone());
@@ -203,7 +204,7 @@ pub fn build(installed: &Installed, layout: &Layout, opts: &LaunchOptions) -> Co
         vars.insert("quickPlayMultiplayer", format!("{host}:{port}"));
     }
 
-    let mut args = Vec::new();
+    let mut args = opts.agent_args.clone();
     args.push(format!("-Xms{}M", opts.memory_min_mb.min(opts.memory_max_mb)));
     args.push(format!("-Xmx{}M", opts.memory_max_mb));
     args.extend(gc_args(opts.gc, installed.java_major));
@@ -336,8 +337,8 @@ mod tests {
                 uuid: "b50ad385-829d-3141-a216-7e7d7539ba7f".into(),
                 access_token: "0".into(),
                 user_type: "legacy".into(),
-                xuid: None,
             },
+            agent_args: vec!["-javaagent:/a.jar=https://p/api/yggdrasil".into()],
             game_dir: "/g".into(),
             memory_min_mb: 1024,
             memory_max_mb: 4096,
@@ -362,7 +363,7 @@ mod tests {
         let layout = Layout::new("/root");
         let cmd = build(&installed(json), &layout, &opts(true));
         let a = cmd.args.join(" ");
-        assert!(a.starts_with("-Xms1024M -Xmx4096M"));
+        assert!(a.starts_with("-javaagent:/a.jar=https://p/api/yggdrasil -Xms1024M -Xmx4096M"), "agent must come first");
         assert!(a.contains("-Dcustom=1"));
         assert!(a.contains("--uuid b50ad385829d3141a2167e7d7539ba7f"));
         assert!(a.contains("--width 1280 --height 720"));

crates/core/src/lib.rs

@@ -5,6 +5,7 @@
 //! tested without a window.
 
 pub mod assets;
+pub mod authlib;
 pub mod http;
 pub mod install;
 pub mod java;
@@ -13,7 +14,6 @@ pub mod libraries;
 pub mod loaders;
 pub mod maven;
 pub mod meta;
-pub mod msa;
 pub mod options;
 pub mod paths;
 pub mod ping;

crates/core/src/msa.rs

@@ -1,212 +0,0 @@
-//! Microsoft account sign-in (device-code flow → Xbox Live → Minecraft).
-//!
-//! Requires an Azure app registration ("client id") that Mojang has approved
-//! for the Minecraft API. The admin configures it in the panel.
-
-use anyhow::{anyhow, bail, Context, Result};
-use serde::{Deserialize, Serialize};
-use serde_json::json;
-use std::time::Duration;
-
-const DEVICE_CODE_URL: &str = "https://login.microsoftonline.com/consumers/oauth2/v2.0/devicecode";
-const TOKEN_URL: &str = "https://login.microsoftonline.com/consumers/oauth2/v2.0/token";
-const SCOPE: &str = "XboxLive.signin offline_access";
-
-#[derive(Debug, Clone, Serialize, Deserialize)]
-pub struct DeviceCode {
-    pub device_code: String,
-    pub user_code: String,
-    pub verification_uri: String,
-    pub expires_in: u64,
-    #[serde(default = "default_interval")]
-    pub interval: u64,
-    #[serde(default)]
-    pub message: String,
-}
-
-fn default_interval() -> u64 {
-    5
-}
-
-#[derive(Debug, Deserialize)]
-struct TokenResponse {
-    access_token: Option<String>,
-    refresh_token: Option<String>,
-    error: Option<String>,
-    error_description: Option<String>,
-}
-
-#[derive(Debug, Clone, Serialize, Deserialize)]
-pub struct MsaSession {
-    pub refresh_token: String,
-    pub mc_access_token: String,
-    /// Unix seconds.
-    pub mc_expires_at: i64,
-    pub profile: McProfile,
-    pub xuid: Option<String>,
-}
-
-#[derive(Debug, Clone, Serialize, Deserialize)]
-pub struct McProfile {
-    pub id: String,
-    pub name: String,
-    #[serde(default)]
-    pub skins: Vec<McSkin>,
-}
-
-#[derive(Debug, Clone, Serialize, Deserialize)]
-pub struct McSkin {
-    pub url: String,
-    #[serde(default)]
-    pub state: String,
-    #[serde(default)]
-    pub variant: Option<String>,
-}
-
-pub async fn start_device_code(client: &reqwest::Client, client_id: &str) -> Result<DeviceCode> {
-    let resp = client.post(DEVICE_CODE_URL).form(&[("client_id", client_id), ("scope", SCOPE)]).send().await?;
-    if !resp.status().is_success() {
-        let body = resp.text().await.unwrap_or_default();
-        bail!("Microsoft rejected the sign-in request: {body}");
-    }
-    Ok(resp.json().await?)
-}
-
-/// Poll until the user finishes signing in, then complete the full chain.
-pub async fn finish_device_code(client: &reqwest::Client, client_id: &str, code: &DeviceCode) -> Result<MsaSession> {
-    let mut interval = code.interval.max(1);
-    let deadline = std::time::Instant::now() + Duration::from_secs(code.expires_in);
-    loop {
-        if std::time::Instant::now() > deadline {
-            bail!("the sign-in code expired, please try again");
-        }
-        tokio::time::sleep(Duration::from_secs(interval)).await;
-        let resp: TokenResponse = client
-            .post(TOKEN_URL)
-            .form(&[
-                ("grant_type", "urn:ietf:params:oauth:grant-type:device_code"),
-                ("client_id", client_id),
-                ("device_code", code.device_code.as_str()),
-            ])
-            .send()
-            .await?
-            .json()
-            .await?;
-        match resp.error.as_deref() {
-            None => {
-                let access = resp.access_token.ok_or_else(|| anyhow!("no access token"))?;
-                let refresh = resp.refresh_token.ok_or_else(|| anyhow!("no refresh token"))?;
-                return complete(client, &access, refresh).await;
-            }
-            Some("authorization_pending") => continue,
-            Some("slow_down") => interval += 5,
-            Some("authorization_declined") => bail!("sign-in was cancelled"),
-            Some("expired_token") => bail!("the sign-in code expired, please try again"),
-            Some(other) => bail!("Microsoft sign-in failed: {other} {}", resp.error_description.unwrap_or_default()),
-        }
-    }
-}
-
-/// Refresh a saved session (used before each launch when the Minecraft
-/// token is close to expiring).
-pub async fn refresh(client: &reqwest::Client, client_id: &str, refresh_token: &str) -> Result<MsaSession> {
-    let resp: TokenResponse = client
-        .post(TOKEN_URL)
-        .form(&[("grant_type", "refresh_token"), ("client_id", client_id), ("refresh_token", refresh_token), ("scope", SCOPE)])
-        .send()
-        .await?
-        .json()
-        .await?;
-    if let Some(err) = resp.error {
-        bail!("your Microsoft session expired ({err}); please sign in again");
-    }
-    let access = resp.access_token.ok_or_else(|| anyhow!("no access token"))?;
-    let refresh = resp.refresh_token.unwrap_or_else(|| refresh_token.to_string());
-    complete(client, &access, refresh).await
-}
-
-#[derive(Deserialize)]
-#[serde(rename_all = "PascalCase")]
-struct XboxResponse {
-    token: String,
-    display_claims: DisplayClaims,
-}
-#[derive(Deserialize)]
-struct DisplayClaims {
-    xui: Vec<Xui>,
-}
-#[derive(Deserialize)]
-struct Xui {
-    uhs: String,
-    #[serde(default)]
-    xid: Option<String>,
-}
-
-#[derive(Deserialize)]
-struct McLogin {
-    access_token: String,
-    expires_in: i64,
-}
-
-async fn complete(client: &reqwest::Client, ms_access: &str, refresh_token: String) -> Result<MsaSession> {
-    // Xbox Live
-    let xbl: XboxResponse = client
-        .post("https://user.auth.xboxlive.com/user/authenticate")
-        .json(&json!({
-            "Properties": {"AuthMethod": "RPS", "SiteName": "user.auth.xboxlive.com", "RpsTicket": format!("d={ms_access}")},
-            "RelyingParty": "http://auth.xboxlive.com",
-            "TokenType": "JWT"
-        }))
-        .send()
-        .await?
-        .error_for_status()
-        .context("Xbox Live authentication failed")?
-        .json()
-        .await?;
-
-    // XSTS
-    let resp = client
-        .post("https://xsts.auth.xboxlive.com/xsts/authorize")
-        .json(&json!({
-            "Properties": {"SandboxId": "RETAIL", "UserTokens": [xbl.token]},
-            "RelyingParty": "rp://api.minecraftservices.com/",
-            "TokenType": "JWT"
-        }))
-        .send()
-        .await?;
-    if resp.status().as_u16() == 401 {
-        let body: serde_json::Value = resp.json().await.unwrap_or_default();
-        let msg = match body.get("XErr").and_then(|v| v.as_u64()) {
-            Some(2148916233) => "this Microsoft account has no Xbox profile yet — sign in once at xbox.com, then try again",
-            Some(2148916235) => "Xbox Live isn't available in your country",
-            Some(2148916236) | Some(2148916237) => "this account needs adult verification on xbox.com",
-            Some(2148916238) => "this is a child account — an adult must add it to a Microsoft family first",
-            _ => "Xbox Live refused the sign-in",
-        };
-        bail!("{msg}");
-    }
-    let xsts: XboxResponse = resp.error_for_status()?.json().await?;
-    let claims = xsts.display_claims.xui.first().ok_or_else(|| anyhow!("missing Xbox user hash"))?;
-    let uhs = claims.uhs.clone();
-    let xuid = claims.xid.clone();
-
-    // Minecraft
-    let mc: McLogin = client
-        .post("https://api.minecraftservices.com/authentication/login_with_xbox")
-        .json(&json!({ "identityToken": format!("XBL3.0 x={uhs};{}", xsts.token) }))
-        .send()
-        .await?
-        .error_for_status()
-        .context("Minecraft services rejected the Xbox token (is the Azure app approved for Minecraft?)")?
-        .json()
-        .await?;
-
-    let resp = client.get("https://api.minecraftservices.com/minecraft/profile").bearer_auth(&mc.access_token).send().await?;
-    if resp.status().as_u16() == 404 {
-        bail!("this Microsoft account doesn't own Minecraft: Java Edition");
-    }
-    let profile: McProfile = resp.error_for_status()?.json().await?;
-
-    let now = std::time::SystemTime::now().duration_since(std::time::UNIX_EPOCH).unwrap().as_secs() as i64;
-    Ok(MsaSession { refresh_token, mc_access_token: mc.access_token, mc_expires_at: now + mc.expires_in, profile, xuid })
-}