Read clientName among other query parameters

src/integration/java/org/jlab/epics2web/ClientNameTest.java

@@ -0,0 +1,60 @@
+package org.jlab.epics2web;
+
+import static org.junit.Assert.assertTrue;
+
+import java.net.URI;
+import java.net.URLEncoder;
+import java.net.http.HttpClient;
+import java.net.http.HttpRequest;
+import java.net.http.HttpResponse;
+import java.net.http.WebSocket;
+import java.nio.charset.StandardCharsets;
+import java.util.UUID;
+import org.junit.Test;
+
+/** Tests that clients are named by the clientName parameter of the WebSocket handshake. */
+public class ClientNameTest {
+
+  private static final HttpClient HTTP = HttpClient.newHttpClient();
+
+  /** The name is read even when the query has other parameters, and may contain = and &. */
+  @Test
+  public void consoleShowsClientNameAmongOtherParameters() throws Exception {
+    String name = "name-test-" + UUID.randomUUID() + "?a=1&b=2";
+    WebSocket socket =
+        HTTP.newWebSocketBuilder()
+            .buildAsync(
+                URI.create(
+                    "ws://localhost:8080/epics2web/monitor?other=1&clientName="
+                        + URLEncoder.encode(name, StandardCharsets.UTF_8)
+                        + "&another=2"),
+                new WebSocket.Listener() {})
+            .join();
+
+    try {
+      assertTrue("Client name not on the console", consoleShows(name.replace("&", "&")));
+    } finally {
+      socket.abort();
+    }
+  }
+
+  /** Waits for the console to show the text; the server may list the client after the handshake. */
+  private static boolean consoleShows(String text) throws Exception {
+    long deadline = System.currentTimeMillis() + 5_000;
+    while (true) {
+      if (get("console").body().contains("<td>" + text + "</td>")) {
+        return true;
+      }
+      if (System.currentTimeMillis() > deadline) {
+        return false;
+      }
+      Thread.sleep(100);
+    }
+  }
+
+  private static HttpResponse<String> get(String path) throws Exception {
+    return HTTP.send(
+        HttpRequest.newBuilder().uri(URI.create("http://localhost:8080/epics2web/" + path)).build(),
+        HttpResponse.BodyHandlers.ofString());
+  }
+}

src/main/java/org/jlab/epics2web/websocket/MonitorEndpoint.java

@@ -14,8 +14,8 @@
 import jakarta.websocket.Session;
 import jakarta.websocket.server.ServerEndpoint;
 import java.io.StringReader;
-import java.io.UnsupportedEncodingException;
 import java.net.URLDecoder;
+import java.nio.charset.StandardCharsets;
 import java.util.Date;
 import java.util.List;
 import java.util.Map;
@@ -77,24 +77,7 @@ public void onOpen(Session session, EndpointConfig config) {
           }
         }
 
-        String name = "";
-        String q = session.getQueryString();
-        if (q != null) {
-          String[] tokens = q.split("=");
-          if (tokens.length == 2) {
-            try {
-              name = URLDecoder.decode(tokens[1], "UTF-8");
-            } catch (UnsupportedEncodingException e) {
-              LOGGER.log(
-                  Level.WARNING,
-                  "JVM doesn't support UTF-8 so can't decode clientName parameter",
-                  e);
-            }
-          }
-          if (name == null) {
-            name = "";
-          }
-        }
+        String name = clientName(session.getQueryString());
 
         session.getUserProperties().put("agent", agent);
         session.getUserProperties().put("ip", ip);
@@ -126,6 +109,34 @@ public void onOpen(Session session, EndpointConfig config) {
     }
   }
 
+  /**
+   * Read the clientName parameter from a handshake's query string. The query may have other
+   * parameters, in any order.
+   *
+   * @param query The raw query string, or null
+   * @return The decoded name, or empty if there's none or it's malformed
+   */
+  static String clientName(String query) {
+    if (query == null) {
+      return "";
+    }
+
+    for (String parameter : query.split("&")) {
+      int equals = parameter.indexOf('=');
+
+      if (equals > 0 && "clientName".equals(parameter.substring(0, equals))) {
+        try {
+          return URLDecoder.decode(parameter.substring(equals + 1), StandardCharsets.UTF_8);
+        } catch (IllegalArgumentException e) {
+          LOGGER.log(Level.FINE, "Malformed clientName parameter: {0}", parameter);
+          return "";
+        }
+      }
+    }
+
+    return "";
+  }
+
   @OnClose
   public void onClose(Session session, CloseReason reason) {
     // LOGGER.log(Level.FINEST, "close; Reason: {0}", reason);

src/main/webapp/resources/js/epics2web.js

@@ -138,7 +138,7 @@ jlab.epics2web.ClientConnection = function (options) {
             let u = this.url;
 
             if(this.clientName !== null) {
-                u = u + '?clientName=' + encodeURIComponent(this.clientName);
+                u = u + (u.indexOf('?') === -1 ? '?' : '&') + 'clientName=' + encodeURIComponent(this.clientName);
             }
 
             socket = new WebSocket(u);

src/test/java/org/jlab/epics2web/websocket/MonitorEndpointTest.java

@@ -1,5 +1,6 @@
 package org.jlab.epics2web.websocket;
 
+import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertTrue;
@@ -55,4 +56,32 @@ public void onCloseStopsWriterWithoutInterrupting() throws Exception {
     assertNull("Write queue not closed", client.writeQueue.take());
     assertTrue(manager.toSet().isEmpty());
   }
+
+  @Test
+  public void clientNameIsReadAmongOtherParameters() {
+    assertEquals("screen", MonitorEndpoint.clientName("clientName=screen"));
+    assertEquals("screen", MonitorEndpoint.clientName("a=1&clientName=screen"));
+    assertEquals("screen", MonitorEndpoint.clientName("clientName=screen&a=1&b"));
+    assertEquals("screen", MonitorEndpoint.clientName("a&clientName=screen"));
+  }
+
+  /** The JavaScript client sends its page's address, which may have a query string of its own. */
+  @Test
+  public void clientNameIsDecoded() {
+    assertEquals(
+        "https://example.org/wedm/screen?edl=a b.edl&x=1",
+        MonitorEndpoint.clientName(
+            "clientName=https%3A%2F%2Fexample.org%2Fwedm%2Fscreen%3Fedl%3Da%20b.edl%26x%3D1"));
+  }
+
+  @Test
+  public void clientNameIsEmptyWhenMissingOrMalformed() {
+    assertEquals("", MonitorEndpoint.clientName(null));
+    assertEquals("", MonitorEndpoint.clientName(""));
+    assertEquals("", MonitorEndpoint.clientName("a=1"));
+    assertEquals("", MonitorEndpoint.clientName("xclientName=screen"));
+    assertEquals("", MonitorEndpoint.clientName("clientName"));
+    assertEquals("", MonitorEndpoint.clientName("clientName="));
+    assertEquals("", MonitorEndpoint.clientName("clientName=%zz"));
+  }
 }