More robust downloading/caching

- better exception catching
- proper error handling
- caching of packs if size, etag, and last modified are the same

core/src/main/java/org/geysermc/geyser/network/UpstreamPacketHandler.java

@@ -284,10 +284,10 @@ public class UpstreamPacketHandler extends LoggingPacketHandler {
             // Ensure we don't a. spam console, and b. spam download/check requests
             if (!brokenResourcePacks.contains(packet.getPackId())) {
                 brokenResourcePacks.add(packet.getPackId());
-                GeyserImpl.getInstance().getLogger().warning("Received a request for a remote pack that the client should have already downloaded!" +
+                GeyserImpl.getInstance().getLogger().warning("Received a request for a remote pack that the client should have already downloaded! " +
                         "Is the pack at the URL " + urlPackCodec.url() + " still available?");
                 // not actually interested in using the download, but this does all the checks we need
-                ResourcePackLoader.downloadPack(urlPackCodec.url());
+                ResourcePackLoader.downloadPack(urlPackCodec.url(), true);
             }
         }
 

core/src/main/java/org/geysermc/geyser/pack/url/GeyserUrlPackCodec.java

@@ -81,7 +81,7 @@ public class GeyserUrlPackCodec extends UrlPackCodec {
     public ResourcePack create() {
         if (this.fallback == null) {
             try {
-                final Path downloadedPack = ResourcePackLoader.downloadPack(url).whenComplete((pack, throwable) -> {
+                final Path downloadedPack = ResourcePackLoader.downloadPack(url, false).whenComplete((pack, throwable) -> {
                     if (throwable != null) {
                         GeyserImpl.getInstance().getLogger().error("Failed to download pack from " + url, throwable);
                         if (GeyserImpl.getInstance().getConfig().isDebugMode()) {

core/src/main/java/org/geysermc/geyser/registry/loader/ResourcePackLoader.java

@@ -200,7 +200,7 @@ public class ResourcePackLoader implements RegistryLoader<Path, Map<String, Reso
         }
     }
 
-    public Map<String, ResourcePack> loadRemotePacks() {
+    private Map<String, ResourcePack> loadRemotePacks() {
         final Path cachedCdnPacksDirectory = GeyserImpl.getInstance().getBootstrap().getConfigFolder().resolve("cache").resolve("remote_packs");
 
         // Download CDN packs to get the pack uuid's
@@ -231,11 +231,8 @@ public class ResourcePackLoader implements RegistryLoader<Path, Map<String, Reso
         return packMap;
     }
 
-    public static CompletableFuture<@Nullable Path> downloadPack(String url) throws IllegalArgumentException {
-
-        //TODO check if our cache pack is fine (size, url hash; head req)
-
-        return WebUtils.checkUrlAndDownloadRemotePack(url).whenCompleteAsync((cachedPath, throwable) -> {
+    public static CompletableFuture<@Nullable Path> downloadPack(String url, boolean force) throws IllegalArgumentException {
+        return WebUtils.checkUrlAndDownloadRemotePack(url, force).whenCompleteAsync((cachedPath, throwable) -> {
             if (cachedPath == null) {
                 // already warned about in WebUtils
                 return;

core/src/main/java/org/geysermc/geyser/util/WebUtils.java

@@ -34,6 +34,7 @@ import javax.naming.directory.InitialDirContext;
 import java.io.*;
 import java.net.HttpURLConnection;
 import java.net.MalformedURLException;
+import java.net.SocketTimeoutException;
 import java.net.URL;
 import java.net.URLEncoder;
 import java.nio.charset.StandardCharsets;
@@ -41,11 +42,15 @@ import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.Paths;
 import java.nio.file.StandardCopyOption;
+import java.util.Arrays;
+import java.util.List;
 import java.util.Map;
 import java.util.concurrent.CompletableFuture;
 
 public class WebUtils {
 
+    private static final Path REMOTE_PACK_CACHE = GeyserImpl.getInstance().getBootstrap().getConfigFolder().resolve("cache").resolve("remote_packs");
+
     /**
      * Makes a web request to the given URL and returns the body as a string
      *
@@ -103,13 +108,25 @@ public class WebUtils {
      * If it is, it will download the pack file and return a path to it
      *
      * @param url The URL to check
+     * @param force If true, the pack will be downloaded even if it is cached
      * @return Path to the downloaded pack file
      */
-    public static CompletableFuture<@Nullable Path> checkUrlAndDownloadRemotePack(String url) {
+    public static CompletableFuture<@Nullable Path> checkUrlAndDownloadRemotePack(String url, boolean force) {
         return CompletableFuture.supplyAsync(() -> {
             try {
                 HttpURLConnection con = (HttpURLConnection) new URL(url).openConnection();
-                con.setRequestProperty("User-Agent", "Geyser-" + GeyserImpl.getInstance().getPlatformType().toString() + "/" + GeyserImpl.VERSION);
+
+                con.setConnectTimeout(10000);
+                con.setReadTimeout(10000);
+                con.setRequestProperty("User-Agent", "Geyser-" + GeyserImpl.getInstance().getPlatformType().platformName() + "/" + GeyserImpl.VERSION);
+                con.setInstanceFollowRedirects(false); // TODO verify
+
+                int responseCode = con.getResponseCode();
+                if (responseCode >= 400) {
+                    GeyserImpl.getInstance().getLogger().error(String.format("Invalid response code from remote pack URL: %s (code: %d)", url, responseCode));
+                    return null;
+                }
+
                 int size = con.getContentLength();
                 String type = con.getContentType();
 
@@ -123,21 +140,49 @@ public class WebUtils {
                     return null;
                 }
 
-                InputStream in = con.getInputStream();
-                Path fileLocation = GeyserImpl.getInstance().getBootstrap().getConfigFolder().resolve("cache").resolve("remote_packs").resolve(url.hashCode() + ".zip");
-                Files.copy(in, fileLocation, StandardCopyOption.REPLACE_EXISTING);
+                Path packLocation = REMOTE_PACK_CACHE.resolve(url.hashCode() + ".zip");
+                Path packMetadata = packLocation.resolveSibling(url.hashCode() + ".metadata");
 
-                if (Files.size(fileLocation) != size) {
-                    GeyserImpl.getInstance().getLogger().error("Downloaded pack has " + Files.size(fileLocation) + " bytes, expected " + size + " bytes");
-                    Files.delete(fileLocation);
+                if (Files.exists(packLocation) && Files.exists(packMetadata)) {
+                    try {
+                        List<String> metadataLines = Files.readAllLines(packMetadata, StandardCharsets.UTF_8);
+                        int cachedSize = Integer.parseInt(metadataLines.get(0));
+                        String cachedEtag = metadataLines.get(1);
+                        long cachedLastModified = Long.parseLong(metadataLines.get(2));
+
+                        if (cachedSize == size && cachedEtag.equals(con.getHeaderField("ETag")) && cachedLastModified == con.getLastModified()) {
+                            GeyserImpl.getInstance().getLogger().debug("Using cached pack for " + url);
+                            return packLocation;
+                        }
+                    } catch (IOException e) {
+                        GeyserImpl.getInstance().getLogger().error("Failed to read cached pack metadata: " + e.getMessage());
+                    }
+                }
+
+                InputStream in = con.getInputStream();
+                Files.copy(in, packLocation, StandardCopyOption.REPLACE_EXISTING);
+
+                if (Files.size(packLocation) != size) {
+                    GeyserImpl.getInstance().getLogger().error("Downloaded pack has " + Files.size(packLocation) + " bytes, expected " + size + " bytes");
+                    Files.delete(packLocation);
                     return null;
                 }
 
-                return fileLocation;
+                try {
+                    Files.write(packMetadata, Arrays.asList(String.valueOf(size), con.getHeaderField("ETag"), String.valueOf(con.getLastModified())));
+                } catch (IOException e) {
+                    GeyserImpl.getInstance().getLogger().error("Failed to write cached pack metadata: " + e.getMessage());
+                }
+
+                return packLocation;
             } catch (MalformedURLException e) {
                 throw new IllegalArgumentException("Malformed URL: " + url);
+            } catch (SocketTimeoutException | ConnectException e) {
+                GeyserImpl.getInstance().getLogger().error("Unable to reach URL: " + url + " (" + e.getMessage() + ")");
+                return null;
             } catch (IOException e) {
-                throw new RuntimeException("Unable to download and save remote resource pack from: " + url + ")");
+                e.printStackTrace(); // TODO yeeeeeeeet
+                throw new RuntimeException("Unable to download and save remote resource pack from: " + url + " (" + e.getMessage() + ")");
             }
         });
     }