Set the user agent header in the Java client (#13168)

src/SignalR/clients/java/signalr/build.gradle

@@ -108,3 +108,27 @@ task generatePOM {
 }
 
 task createPackage(dependsOn: [jar,sourceJar,javadocJar,generatePOM])
+
+task generateVersionClass {
+    inputs.property "version", project.version
+    outputs.dir "$buildDir/generated"
+    doFirst {
+        def versionFile = file("$buildDir/../src/main/java/com/microsoft/signalr/Version.java")
+        versionFile.parentFile.mkdirs()
+        versionFile.text =
+                """
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+package com.microsoft.signalr;
+
+class Version {
+    public static String getDetailedVersion() {
+        return "$project.version";
+    }
+}
+"""
+    }
+}
+
+compileJava.dependsOn generateVersionClass

src/SignalR/clients/java/signalr/src/main/java/com/microsoft/signalr/HubConnection.java

@@ -327,6 +327,7 @@ public class HubConnection {
         handshakeResponseSubject = CompletableSubject.create();
         handshakeReceived = false;
         CompletableSubject tokenCompletable = CompletableSubject.create();
+        localHeaders.put(UserAgentHelper.getUserAgentName(), UserAgentHelper.createUserAgentString());
         if (headers != null) {
             this.localHeaders.putAll(headers);
         }

src/SignalR/clients/java/signalr/src/main/java/com/microsoft/signalr/UserAgentHelper.java

@@ -0,0 +1,54 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+package com.microsoft.signalr;
+
+public class UserAgentHelper {
+
+    private final static String USER_AGENT = "User-Agent";
+
+    public static String getUserAgentName() {
+        return USER_AGENT;
+    }
+
+    public static String createUserAgentString() {
+        StringBuilder agentBuilder = new StringBuilder("Microsoft SignalR/");
+
+        // Parsing version numbers
+        String detailedVersion = Version.getDetailedVersion();
+        agentBuilder.append(getVersion(detailedVersion));
+        agentBuilder.append("; (");
+        agentBuilder.append(detailedVersion);
+        agentBuilder.append("; ");
+
+        // Getting the OS name
+        agentBuilder.append(getOS());
+        agentBuilder.append("; Java; ");
+
+        // Vendor and Version
+        agentBuilder.append(getJavaVersion());
+        agentBuilder.append("; ");
+        agentBuilder.append(getJavaVendor());
+        agentBuilder.append(")");
+
+        return agentBuilder.toString();
+    }
+
+    static String getVersion(String detailedVersion) {
+        // Getting the index of the second . so we can return just the major and minor version.
+        int shortVersionIndex = detailedVersion.indexOf(".", detailedVersion.indexOf(".") + 1);
+        return detailedVersion.substring(0, shortVersionIndex);
+    }
+
+    static String getJavaVendor() {
+        return System.getProperty("java.vendor");
+    }
+
+    static String getJavaVersion() {
+        return System.getProperty("java.version");
+    }
+
+    static String getOS() {
+        return System.getProperty("os.name");
+    }
+}

src/SignalR/clients/java/signalr/src/main/java/com/microsoft/signalr/Version.java

@@ -0,0 +1,11 @@
+
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+package com.microsoft.signalr;
+
+class Version {
+    public static String getDetailedVersion() {
+        return "99.99.99-dev";
+    }
+}

src/SignalR/clients/java/signalr/src/test/java/com/microsoft/signalr/HubConnectionTest.java

@@ -2185,6 +2185,77 @@ class HubConnectionTest {
         }
     }
 
+    @Test
+    public void userAgentHeaderIsSet() {
+        AtomicReference<String> header = new AtomicReference<>();
+        TestHttpClient client = new TestHttpClient()
+                .on("POST", "http://example.com/negotiate",
+                        (req) -> {
+                            header.set(req.getHeaders().get("User-Agent"));
+                            return Single.just(new HttpResponse(200, "", "{\"connectionId\":\"bVOiRPG8-6YiJ6d7ZcTOVQ\",\""
+                                    + "availableTransports\":[{\"transport\":\"WebSockets\",\"transferFormats\":[\"Text\",\"Binary\"]}]}"));
+                        });
+
+        MockTransport transport = new MockTransport();
+        HubConnection hubConnection = HubConnectionBuilder.create("http://example.com")
+                .withTransportImplementation(transport)
+                .withHttpClient(client)
+                .build();
+
+        hubConnection.start().timeout(1, TimeUnit.SECONDS).blockingAwait();
+        assertEquals(HubConnectionState.CONNECTED, hubConnection.getConnectionState());
+        hubConnection.stop();
+
+        assertTrue(header.get().startsWith("Microsoft SignalR/"));
+    }
+
+    @Test
+    public void userAgentHeaderCanBeOverwritten() {
+        AtomicReference<String> header = new AtomicReference<>();
+        TestHttpClient client = new TestHttpClient()
+                .on("POST", "http://example.com/negotiate",
+                        (req) -> {
+                            header.set(req.getHeaders().get("User-Agent"));
+                            return Single.just(new HttpResponse(200, "", "{\"connectionId\":\"bVOiRPG8-6YiJ6d7ZcTOVQ\",\""
+                                    + "availableTransports\":[{\"transport\":\"WebSockets\",\"transferFormats\":[\"Text\",\"Binary\"]}]}"));
+                        });
+
+        MockTransport transport = new MockTransport();
+        HubConnection hubConnection = HubConnectionBuilder.create("http://example.com")
+                .withTransportImplementation(transport)
+                .withHttpClient(client)
+                .withHeader("User-Agent", "Updated Value")
+                .build();
+
+        hubConnection.start().timeout(1, TimeUnit.SECONDS).blockingAwait();
+        assertEquals(HubConnectionState.CONNECTED, hubConnection.getConnectionState());
+        hubConnection.stop();
+        assertEquals("Updated Value", header.get());
+    }
+
+    @Test
+    public void userAgentCanBeCleared() {
+        AtomicReference<String> header = new AtomicReference<>();
+        TestHttpClient client = new TestHttpClient()
+                .on("POST", "http://example.com/negotiate",
+                        (req) -> {
+                            header.set(req.getHeaders().get("User-Agent"));
+                            return Single.just(new HttpResponse(200, "", "{\"connectionId\":\"bVOiRPG8-6YiJ6d7ZcTOVQ\",\""
+                                    + "availableTransports\":[{\"transport\":\"WebSockets\",\"transferFormats\":[\"Text\",\"Binary\"]}]}"));
+                        });
+
+        MockTransport transport = new MockTransport();
+        HubConnection hubConnection = HubConnectionBuilder.create("http://example.com")
+                .withTransportImplementation(transport)
+                .withHttpClient(client)
+                .withHeader("User-Agent", "")
+                .build();
+
+        hubConnection.start().timeout(1, TimeUnit.SECONDS).blockingAwait();
+        assertEquals(HubConnectionState.CONNECTED, hubConnection.getConnectionState());
+        hubConnection.stop();
+        assertEquals("", header.get());
+    }
     @Test
     public void headersAreSetAndSentThroughBuilder() {
         AtomicReference<String> header = new AtomicReference<>();

src/SignalR/clients/java/signalr/src/test/java/com/microsoft/signalr/UserAgentTest.java

@@ -0,0 +1,54 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+package com.microsoft.signalr;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+
+import java.util.stream.Stream;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.MethodSource;
+
+public class UserAgentTest {
+
+    private static Stream<Arguments> Versions() {
+        return Stream.of(
+                Arguments.of("1.0.0", "1.0"),
+                Arguments.of("3.1.4-preview9-12345", "3.1"),
+                Arguments.of("3.1.4-preview9-12345-extrastuff", "3.1"),
+                Arguments.of("99.99.99-dev", "99.99"));
+    }
+
+    @ParameterizedTest
+    @MethodSource("Versions")
+    public void getVersionFromDetailedVersion(String detailedVersion, String version) {
+        assertEquals(version, UserAgentHelper.getVersion(detailedVersion));
+    }
+
+    @Test
+    public void verifyJavaVendor(){
+        assertEquals(System.getProperty("java.vendor"), UserAgentHelper.getJavaVendor());
+    }
+
+    @Test
+    public void verifyJavaVersion(){
+        assertEquals(System.getProperty("java.version"), UserAgentHelper.getJavaVersion());
+    }
+
+    @Test
+    public void checkUserAgentString(){
+        String userAgent = UserAgentHelper.createUserAgentString();
+        assertNotNull(userAgent);
+
+        String detailedVersion = Version.getDetailedVersion();
+        String handMadeUserAgent = "Microsoft SignalR/" + UserAgentHelper.getVersion(detailedVersion) +
+                "; (" + detailedVersion + "; " + UserAgentHelper.getOS() + "; Java; " +
+                UserAgentHelper.getJavaVersion() + "; " + UserAgentHelper.getJavaVendor() + ")";
+
+        assertEquals(handMadeUserAgent, userAgent);
+    }
+}