Run applets that use LiveConnect or load images through the proxy

appletviewer has no netscape.javascript.JSObject, so applets that touch
JavaScript fail to load, and Java 8 denies applets the URLPermission they
need to fetch through an HTTP proxy. Add a JSObject stand-in with a working
document.cookie and a policy granting HTTP URL access.

streaming/streamer/Dockerfile

@@ -1,3 +1,9 @@
+FROM eclipse-temurin:8-jdk AS jsobject
+COPY jsobject /src
+RUN mkdir /classes && \
+  javac -d /classes $(find /src -name '*.java') && \
+  jar cf /jsobject.jar -C /classes .
+
 FROM ghcr.io/linuxserver/baseimage-selkies:debiantrixie
 
 RUN apt-get update && \
@@ -12,3 +18,4 @@ RUN apt-get update && \
   rm -rf /var/lib/apt/lists/*
 
 COPY root/ /
+COPY --from=jsobject /jsobject.jar /opt/flashpoint/jsobject.jar

streaming/streamer/README.md

@@ -33,3 +33,8 @@ different game, set `GAME_ID` and recreate the container. The launch log is at
 the game server, mounts the game's zip through the server's `mountzip` API, and
 runs the game's application with its HTTP proxy pointed at the game server.
 Selkies restarts the game when it exits (`RESTART_APP`).
+
+`appletviewer` lacks two things applets got from the browser's Java plugin, so
+the image adds them: a `netscape.javascript.JSObject` stand-in (`jsobject/`)
+whose window has a working `document.cookie`, and a policy allowing HTTP
+requests through the game server's proxy.

streaming/streamer/jsobject/netscape/javascript/Document.java

@@ -0,0 +1,37 @@
+package netscape.javascript;
+
+import java.util.LinkedHashMap;
+import java.util.Map;
+
+/** A document whose cookie member behaves like document.cookie in a browser. */
+class Document extends JSObject {
+    private final Map<String, String> cookies = new LinkedHashMap<String, String>();
+
+    @Override
+    public Object getMember(String name) throws JSException {
+        if (!name.equals("cookie")) {
+            return super.getMember(name);
+        }
+        StringBuilder sb = new StringBuilder();
+        for (Map.Entry<String, String> cookie : cookies.entrySet()) {
+            if (sb.length() > 0) {
+                sb.append("; ");
+            }
+            sb.append(cookie.getKey()).append('=').append(cookie.getValue());
+        }
+        return sb.toString();
+    }
+
+    @Override
+    public void setMember(String name, Object value) throws JSException {
+        if (!name.equals("cookie")) {
+            super.setMember(name, value);
+            return;
+        }
+        String pair = String.valueOf(value).split(";", 2)[0];
+        int eq = pair.indexOf('=');
+        if (eq > 0) {
+            cookies.put(pair.substring(0, eq).trim(), pair.substring(eq + 1).trim());
+        }
+    }
+}

streaming/streamer/jsobject/netscape/javascript/JSException.java

@@ -0,0 +1,10 @@
+package netscape.javascript;
+
+public class JSException extends RuntimeException {
+    public JSException() {
+    }
+
+    public JSException(String message) {
+        super(message);
+    }
+}

streaming/streamer/jsobject/netscape/javascript/JSObject.java

@@ -0,0 +1,53 @@
+package netscape.javascript;
+
+import java.applet.Applet;
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * Stand-in for the browser's LiveConnect bridge, which appletviewer lacks. The
+ * window holds a document with a working cookie; calls into JavaScript do nothing.
+ */
+public class JSObject {
+    private static JSObject window;
+
+    private final Map<String, Object> members = new HashMap<String, Object>();
+
+    protected JSObject() {
+    }
+
+    public static synchronized JSObject getWindow(Applet applet) throws JSException {
+        if (window == null) {
+            window = new JSObject();
+            window.setMember("document", new Document());
+        }
+        return window;
+    }
+
+    public Object call(String methodName, Object[] args) throws JSException {
+        return null;
+    }
+
+    public Object eval(String s) throws JSException {
+        return null;
+    }
+
+    public Object getMember(String name) throws JSException {
+        return members.get(name);
+    }
+
+    public void setMember(String name, Object value) throws JSException {
+        members.put(name, value);
+    }
+
+    public void removeMember(String name) throws JSException {
+        members.remove(name);
+    }
+
+    public Object getSlot(int index) throws JSException {
+        return null;
+    }
+
+    public void setSlot(int index, Object value) throws JSException {
+    }
+}

streaming/streamer/root/opt/flashpoint/applet.policy

@@ -0,0 +1,3 @@
+grant {
+    permission java.net.URLPermission "http:*", "*:*";
+};

streaming/streamer/root/usr/local/bin/fp-launch

@@ -34,6 +34,8 @@ fi
 echo "Launching $ID: $app $cmd"
 case ${app,,} in
   'fpsoftware\startjava.bat' | 'fpsoftware\startjavainbrowser.bat')
+    # Applets expect the browser's JavaScript bridge and a browser-like network policy
+    export JAVA_TOOL_OPTIONS="-Xbootclasspath/a:/opt/flashpoint/jsobject.jar -Djava.security.policy=/opt/flashpoint/applet.policy"
     FP_PATH=$FP_PATH exec "$FP_PATH/FPSoftware/startJava.sh" "$cmd" ;;
   *)
     echo "Unsupported application: $app" >&2; exit 1 ;;