Add support for setting the user agent for sync requests

CHANGELOG.md

@@ -1,7 +1,12 @@
 x.y.z Release notes (yyyy-MM-dd)
 =============================================================
 ### Enhancements
-* None.
+* Add a User-Agent header to HTTP requests made to the Realm Object Server. By
+  default, this contains information about the Realm library version and your
+  app's bundle ID. The application identifier can be customized by setting
+  `RLMSyncManager.sharedManager.userAgent`/`SyncManager.shared.userAgent` prior
+  to opening a synchronized Realm.
+  (PR: https://github.com/realm/realm-cocoa/pull/6007).
 
 ### Fixed
 * <How to hit and notice issue? what was the impact?> ([#????](https://github.com/realm/realm-js/issues/????), since v?.?.?)

Realm/ObjectServerTests/RLMSyncTestCase.mm

@@ -526,6 +526,7 @@ - (void)setUp {
                            withIntermediateDirectories:YES attributes:nil error:&error];
     s_managerForTest = [[RLMSyncManager alloc] initWithCustomRootDirectory:clientDataRoot];
     [RLMSyncManager sharedManager].logLevel = RLMSyncLogLevelOff;
+    [RLMSyncManager sharedManager].userAgent = self.name;
 }
 
 - (void)tearDown {

Realm/RLMSyncManager.h

@@ -76,11 +76,21 @@ typedef void(^RLMSyncErrorReportingBlock)(NSError *, RLMSyncSession * _Nullable)
 @property (nullable, nonatomic, copy) RLMSyncErrorReportingBlock errorHandler;
 
 /**
- A reverse-DNS string uniquely identifying this application. In most cases this is automatically set by the SDK, and
- does not have to be explicitly configured.
+ A reverse-DNS string uniquely identifying this application. In most cases this
+ is automatically set by the SDK, and does not have to be explicitly configured.
  */
 @property (nonatomic, copy) NSString *appID;
 
+/**
+ A string identifying this application which is included in the User-Agent
+ header of sync connections. By default, this will be the application's bundle
+ identifier.
+
+ This property must be set prior to opening a synchronized Realm for the first
+ time. Any modifications made after opening a Realm will be ignored.
+ */
+@property (nonatomic, copy) NSString *userAgent;
+
 /**
  The logging threshold which newly opened synced Realms will use. Defaults to
  `RLMSyncLogLevelInfo`.

Realm/RLMSyncManager.mm

@@ -29,6 +29,10 @@
 #import "sync/sync_manager.hpp"
 #import "sync/sync_session.hpp"
 
+#if !defined(REALM_COCOA_VERSION)
+#import "RLMVersion.h"
+#endif
+
 using namespace realm;
 using Level = realm::util::Logger::Level;
 
@@ -111,6 +115,7 @@ - (instancetype)initWithCustomRootDirectory:(NSURL *)rootDirectory {
         auto mode = should_encrypt ? SyncManager::MetadataMode::Encryption : SyncManager::MetadataMode::NoEncryption;
         rootDirectory = rootDirectory ?: [NSURL fileURLWithPath:RLMDefaultDirectoryForBundleIdentifier(nil)];
         SyncManager::shared().configure(rootDirectory.path.UTF8String, mode, "", none, true);
+        self.userAgent = self.appID;
         return self;
     }
     return nil;
@@ -123,6 +128,17 @@ - (NSString *)appID {
     return _appID;
 }
 
+- (void)setUserAgent:(NSString *)userAgent {
+    bool isSwift = !!NSClassFromString(@"RealmSwiftObjectUtil");
+    auto fullUserAgent = [[NSMutableString alloc] initWithFormat:@"Realm %@/%@",
+                          isSwift ? @"Swift" : @"Objective C", REALM_COCOA_VERSION];
+    if (userAgent.length > 0) {
+        [fullUserAgent appendFormat:@" %@", userAgent];
+    }
+    SyncManager::shared().set_user_agent(RLMStringDataWithNSString(fullUserAgent));
+    _userAgent = userAgent;
+}
+
 #pragma mark - Passthrough properties
 
 - (RLMSyncLogLevel)logLevel {

dependencies.list

@@ -1,4 +1,4 @@
 VERSION=3.11.2
 REALM_CORE_VERSION=5.12.1
 REALM_SYNC_VERSION=3.13.3
-REALM_OBJECT_SERVER_VERSION=3.11.5
+REALM_OBJECT_SERVER_VERSION=3.13.1