Fix Mojang auth failing due to Mojang rejecting requests to the profile endpoint

launcher/minecraft/auth/Parsers.cpp

@@ -212,6 +212,176 @@ bool parseMinecraftProfile(QByteArray & data, MinecraftProfile &output) {
     return true;
 }
 
+namespace {
+	// these skin URLs are for the MHF_Steve and MHF_Alex accounts (made by a Mojang employee)
+	// they are needed because the session server doesn't return skin urls for default skins
+    static const QString SKIN_URL_STEVE = "http://textures.minecraft.net/texture/1a4af718455d4aab528e7a61f86fa25e6a369d1768dcb13f7df319a713eb810b";
+    static const QString SKIN_URL_ALEX = "http://textures.minecraft.net/texture/83cee5ca6afcdb171285aa00e8049c297b2dbeba0efb8ff970a5677a1b644032";
+
+    bool isDefaultModelSteve(QString uuid) {
+        // need to calculate *Java* hashCode of UUID
+        // if number is even, skin/model is steve, otherwise it is alex
+
+        // just in case dashes are in the id
+        uuid.remove('-');
+
+        if (uuid.size() != 32) {
+            return true;
+        }
+
+        // qulonglong is guaranteed to be 64 bits
+        // we need to use unsigned numbers to guarantee truncation below
+        qulonglong most = uuid.left(16).toULongLong(nullptr, 16);
+        qulonglong least = uuid.right(16).toULongLong(nullptr, 16);
+        qulonglong xored = most ^ least;
+        return ((static_cast<quint32>(xored >> 32)) ^ static_cast<quint32>(xored)) % 2 == 0;
+    }
+}
+
+/**
+Uses session server for skin/cape lookup instead of profile,
+because locked Mojang accounts cannot access profile endpoint
+(https://api.minecraftservices.com/minecraft/profile/)
+
+ref: https://wiki.vg/Mojang_API#UUID_to_Profile_and_Skin.2FCape
+
+{
+    "id": "<profile identifier>",
+    "name": "<player name>",
+    "properties": [
+        {
+            "name": "textures",
+            "value": "<base64 string>"
+        }
+    ]
+}
+
+decoded base64 "value":
+{
+    "timestamp": <java time in ms>,
+    "profileId": "<profile uuid>",
+    "profileName": "<player name>",
+    "textures": {
+        "SKIN": {
+            "url": "<player skin URL>"
+        },
+        "CAPE": {
+            "url": "<player cape URL>"
+        }
+    }
+}
+*/
+
+bool parseMinecraftProfileMojang(QByteArray & data, MinecraftProfile &output) {
+    qDebug() << "Parsing Minecraft profile...";
+#ifndef NDEBUG
+    qDebug() << data;
+#endif
+
+    QJsonParseError jsonError;
+    QJsonDocument doc = QJsonDocument::fromJson(data, &jsonError);
+    if(jsonError.error) {
+        qWarning() << "Failed to parse response as JSON: " << jsonError.errorString();
+        return false;
+    }
+
+    auto obj = doc.object();
+    if(!getString(obj.value("id"), output.id)) {
+        qWarning() << "Minecraft profile id is not a string";
+        return false;
+    }
+
+    if(!getString(obj.value("name"), output.name)) {
+        qWarning() << "Minecraft profile name is not a string";
+        return false;
+    }
+
+    auto propsArray = obj.value("properties").toArray();
+    QByteArray texturePayload;
+    for( auto p : propsArray) {
+        auto pObj = p.toObject();
+        auto name = pObj.value("name");
+        if (!name.isString() || name.toString() != "textures") {
+            continue;
+        }
+
+        auto value = pObj.value("value");
+        if (value.isString()) {
+            texturePayload = QByteArray::fromBase64(value.toString().toUtf8(), QByteArray::AbortOnBase64DecodingErrors);
+        }
+
+        if (!texturePayload.isEmpty()) {
+            break;
+        }
+    }
+
+    if (texturePayload.isNull()) {
+        qWarning() << "No texture payload data";
+        return false;
+    }
+
+    doc = QJsonDocument::fromJson(texturePayload, &jsonError);
+    if(jsonError.error) {
+        qWarning() << "Failed to parse response as JSON: " << jsonError.errorString();
+        return false;
+    }
+
+    obj = doc.object();
+    auto textures = obj.value("textures");
+    if (!textures.isObject()) {
+        qWarning() << "No textures array in response";
+        return false;
+    }
+
+    Skin skinOut;
+    // fill in default skin info ourselves, as this endpoint doesn't provide it
+    bool steve = isDefaultModelSteve(output.id);
+    skinOut.variant = steve ? "classic" : "slim";
+    skinOut.url = steve ? SKIN_URL_STEVE : SKIN_URL_ALEX;
+    // sadly we can't figure this out, but I don't think it really matters...
+    skinOut.id = "00000000-0000-0000-0000-000000000000";
+    Cape capeOut;
+    auto tObj = textures.toObject();
+    for (auto idx = tObj.constBegin(); idx != tObj.constEnd(); ++idx) {
+        if (idx->isObject()) {
+            if (idx.key() == "SKIN") {
+                auto skin = idx->toObject();
+                if (!getString(skin.value("url"), skinOut.url)) {
+                    qWarning() << "Skin url is not a string";
+                    return false;
+                }
+
+                auto maybeMeta = skin.find("metadata");
+                if (maybeMeta != skin.end() && maybeMeta->isObject()) {
+                    auto meta = maybeMeta->toObject();
+                    // might not be present
+                    getString(meta.value("model"), skinOut.variant);
+                }
+            }
+            else if (idx.key() == "CAPE") {
+                auto cape = idx->toObject();
+                if (!getString(cape.value("url"), capeOut.url)) {
+                    qWarning() << "Cape url is not a string";
+                    return false;
+                }
+
+                // we don't know the cape ID as it is not returned from the session server
+                // so just fake it - changing capes is probably locked anyway :(
+                capeOut.alias = "cape";
+            }
+        }
+    }
+
+    output.skin = skinOut;
+    if (capeOut.alias == "cape") {
+        output.capes = QMap<QString, Cape>({{capeOut.alias, capeOut}});
+        output.currentCape = capeOut.alias;
+    }
+
+    output.validity = Katabasis::Validity::Certain;
+    return true;
+}
+
 bool parseMinecraftEntitlements(QByteArray & data, MinecraftEntitlement &output) {
     qDebug() << "Parsing Minecraft entitlements...";
 #ifndef NDEBUG