Use device IP addresses to connect to RPC host

It still only tries localhost for the simulator, but for devices, we now get a list of possible IP addresses to attempt to connect to before throw a more helpful exception.

Resolves #284 and fixes #276

lib/browser/.eslintrc

@@ -13,6 +13,7 @@
     "sourceType": "module"
   },
   "rules": {
+    "no-console": 0,
     "strict": 0
   }
 }

lib/browser/index.js

@@ -18,6 +18,7 @@
 
 'use strict';
 
+import { NativeModules } from 'react-native';
 import { keys, propTypes, objectTypes } from './constants';
 import * as lists from './lists';
 import * as objects from './objects';
@@ -25,6 +26,7 @@ import * as results from './results';
 import * as rpc from './rpc';
 import * as util from './util';
 
+const {debugHosts, debugPort} = NativeModules.Realm;
 const listenersKey = Symbol();
 
 rpc.registerTypeConverter(objectTypes.LIST, lists.create);
@@ -162,5 +164,24 @@ Object.defineProperties(Realm, {
     },
 });
 
+for (let i = 0, len = debugHosts.length; i < len; i++) {
+    try {
         // The session ID refers to the Realm constructor object in the RPC server.
-Realm[keys.id] = rpc.createSession();
+        Realm[keys.id] = rpc.createSession(debugHosts[i] + ':' + debugPort);
+        break;
+    } catch (e) {
+        // Only throw exception after all hosts have been tried.
+        if (i < len - 1) {
+            continue;
+        }
+
+        // Log the original exception for debugging purposes.
+        console.error(e);
+
+        throw new Error(
+            'Realm failed to connect to the embedded debug server inside the app. ' +
+            'If attempting to use Chrome debugging from a device, ensure the device is ' +
+            'reachable on the same network as this machine.'
+        );
+    }
+}

lib/browser/rpc.js

@@ -21,12 +21,11 @@
 import * as base64 from './base64';
 import { keys, objectTypes } from './constants';
 
-const DEVICE_HOST = 'localhost:8082';
-
 const {id: idKey, realm: realmKey} = keys;
 const typeConverters = {};
 
 let XMLHttpRequest = global.originalXMLHttpRequest || global.XMLHttpRequest;
+let sessionHost;
 let sessionId;
 
 // Check if XMLHttpRequest has been overridden, and get the native one if that's the case.
@@ -45,8 +44,17 @@ export function registerTypeConverter(type, handler) {
     typeConverters[type] = handler;
 }
 
-export function createSession() {
+export function createSession(host) {
+    let oldHost = sessionHost;
+
+    try {
+        sessionHost = host;
         sessionId = sendRequest('create_session');
+    } catch (e) {
+        sessionHost = oldHost;
+        throw e;
+    }
+
     return sessionId;
 }
 
@@ -158,11 +166,15 @@ function deserializeDict(realmId, info) {
 }
 
 function sendRequest(command, data) {
+    if (!sessionHost) {
+        throw new Error('Must first create RPC session with a valid host');
+    }
+
     data = Object.assign({}, data, sessionId ? {sessionId} : null);
 
     let body = JSON.stringify(data);
     let request = new XMLHttpRequest();
-    let url = 'http://' + DEVICE_HOST + '/' + command;
+    let url = 'http://' + sessionHost + '/' + command;
 
     request.open('POST', url, false);
     request.send(body);

react-native/RealmReact.mm

@@ -24,7 +24,11 @@
 #import "shared_realm.hpp"
 
 #import <objc/runtime.h>
+#import <arpa/inet.h>
 #import <dlfcn.h>
+#import <ifaddrs.h>
+#import <netdb.h>
+#import <net/if.h>
 
 #if DEBUG
 #import <GCDWebServer/Core/GCDWebServer.h>
@@ -32,6 +36,8 @@
 #import <GCDWebServer/Responses/GCDWebServerDataResponse.h>
 #import <GCDWebServer/Responses/GCDWebServerErrorResponse.h>
 #import "rpc.hpp"
+
+#define WEB_SERVER_PORT 8082
 #endif
 
 @interface NSObject ()
@@ -118,6 +124,23 @@ extern "C" JSGlobalContextRef RealmReactGetJSGlobalContextForExecutor(id executo
     return dispatch_get_main_queue();
 }
 
+- (NSDictionary *)constantsToExport {
+#if DEBUG
+#if TARGET_IPHONE_SIMULATOR
+    NSArray *hosts = @[@"localhost"];
+#else
+    NSArray *hosts = [self getIPAddresses];
+#endif
+
+    return @{
+        @"debugHosts": hosts,
+        @"debugPort": @(WEB_SERVER_PORT),
+    };
+#else
+    return @{};
+#endif
+}
+
 - (void)addListenerForEvent:(NSString *)eventName handler:(RealmReactEventHandler)handler {
     NSMutableOrderedSet *handlers = _eventHandlers[eventName];
     if (!handlers) {
@@ -138,6 +161,60 @@ RCT_REMAP_METHOD(emit, emitEvent:(NSString *)eventName withObject:(id)object) {
 }
 
 #if DEBUG
+- (NSArray *)getIPAddresses {
+    static const char * const wifiInterface = "en0";
+
+    struct ifaddrs *ifaddrs;
+    if (getifaddrs(&ifaddrs)) {
+        NSLog(@"Failed to get interface addresses: %s", strerror(errno));
+        return @[];
+    }
+
+    NSMutableArray *ipAddresses = [[NSMutableArray alloc] init];
+    char host[INET6_ADDRSTRLEN];
+
+    for (struct ifaddrs *ifaddr = ifaddrs; ifaddr; ifaddr = ifaddr->ifa_next) {
+        if ((ifaddr->ifa_flags & IFF_LOOPBACK) || !(ifaddr->ifa_flags & IFF_UP)) {
+            // Ignore loopbacks and interfaces that aren't up.
+            continue;
+        }
+
+        struct sockaddr *addr = ifaddr->ifa_addr;
+        if (addr->sa_family == AF_INET) {
+            // Ignore link-local ipv4 addresses.
+            in_addr_t sin_addr = ((struct sockaddr_in *)addr)->sin_addr.s_addr;
+            if (IN_LOOPBACK(sin_addr) || IN_LINKLOCAL(sin_addr) || IN_ZERONET(sin_addr)) {
+                continue;
+            }
+        }
+        else if (addr->sa_family == AF_INET6) {
+            // Ignore link-local ipv6 addresses.
+            struct in6_addr *sin6_addr = &((struct sockaddr_in6 *)addr)->sin6_addr;
+            if (IN6_IS_ADDR_LOOPBACK(sin6_addr) || IN6_IS_ADDR_LINKLOCAL(sin6_addr) || IN6_IS_ADDR_UNSPECIFIED(sin6_addr)) {
+                continue;
+            }
+        }
+        else {
+            // Ignore addresses that are not ipv4 or ipv6.
+            continue;
+        }
+
+        if (strcmp(ifaddr->ifa_name, wifiInterface)) {
+            // Ignore non-wifi addresses.
+            continue;
+        }
+        if (int error = getnameinfo(addr, addr->sa_len, host, sizeof(host), NULL, 0, NI_NUMERICHOST)) {
+            NSLog(@"Couldn't resolve host name for address: %s", gai_strerror(error));
+            continue;
+        }
+
+        [ipAddresses addObject:@(host)];
+    }
+    
+    freeifaddrs(ifaddrs);
+    return [ipAddresses copy];
+}
+
 - (void)startRPC {
     [GCDWebServer setLogLevel:3];
     _webServer = [[GCDWebServer alloc] init];
@@ -178,7 +255,7 @@ RCT_REMAP_METHOD(emit, emitEvent:(NSString *)eventName withObject:(id)object) {
         return response;
     }];
 
-    [_webServer startWithPort:8082 bonjourName:nil];
+    [_webServer startWithPort:WEB_SERVER_PORT bonjourName:nil];
     return;
 }
 

react-native/android/src/main/java/io/realm/react/RealmAnalytics.java

@@ -101,8 +101,7 @@ public class RealmAnalytics {
     }
 
     public static boolean shouldExecute() {
-        return System.getenv("REALM_DISABLE_ANALYTICS") == null
-            && (isRunningOnGenymotion() || isRunningOnStockEmulator());
+        return System.getenv("REALM_DISABLE_ANALYTICS") == null && isRunningOnEmulator();
     }
 
     private void send() {
@@ -152,12 +151,9 @@ public class RealmAnalytics {
                 .replaceAll("%OS_VERSION%", System.getProperty("os.version"));
     }
 
-    private static boolean isRunningOnGenymotion() {
-        return Build.FINGERPRINT.contains("vbox");
-    }
-
-    private static boolean isRunningOnStockEmulator() {
-        return Build.FINGERPRINT.contains("generic");
+    public static boolean isRunningOnEmulator() {
+        // Check if running in Genymotion or on the stock emulator.
+        return Build.FINGERPRINT.contains("vbox") || Build.FINGERPRINT.contains("generic");
     }
 
     /**

react-native/android/src/main/java/io/realm/react/RealmReactModule.java

@@ -9,8 +9,15 @@ import com.facebook.react.bridge.ReactContextBaseJavaModule;
 import com.facebook.soloader.SoLoader;
 
 import java.io.IOException;
+import java.net.InetAddress;
+import java.net.NetworkInterface;
+import java.net.SocketException;
+import java.util.Arrays;
+import java.util.ArrayList;
 import java.util.Collections;
+import java.util.Enumeration;
 import java.util.HashMap;
+import java.util.List;
 import java.util.Map;
 import java.util.concurrent.CountDownLatch;
 
@@ -58,7 +65,18 @@ public class RealmReactModule extends ReactContextBaseJavaModule {
         if (!isContextInjected()) {
             startWebServer();
         }
-        return Collections.EMPTY_MAP;
+
+        List<String> hosts;
+        if (RealmAnalytics.isRunningOnEmulator()) {
+            hosts = Arrays.asList(new String[]{"localhost"});
+        } else {
+            hosts = getIPAddresses();
+        }
+
+        HashMap<String, Object> constants = new HashMap<String, Object>();
+        constants.put("debugHosts", hosts);
+        constants.put("debugPort", DEFAULT_PORT);
+        return constants;
     }
 
     @Override
@@ -67,6 +85,35 @@ public class RealmReactModule extends ReactContextBaseJavaModule {
         stopWebServer();
     }
 
+    private List<String> getIPAddresses() {
+        ArrayList<String> ipAddresses = new ArrayList<String>();
+
+        try {
+            Enumeration<NetworkInterface> networkInterfaces = NetworkInterface.getNetworkInterfaces();
+
+            while (networkInterfaces.hasMoreElements()) {
+                NetworkInterface networkInterface = networkInterfaces.nextElement();
+                if (networkInterface.isLoopback() || !networkInterface.isUp()) {
+                    continue;
+                }
+
+                Enumeration<InetAddress> addresses = networkInterface.getInetAddresses();
+                while (addresses.hasMoreElements()) {
+                    InetAddress address = addresses.nextElement();
+                    if (address.isLoopbackAddress() || address.isLinkLocalAddress() || address.isAnyLocalAddress()) {
+                        continue;
+                    }
+
+                    ipAddresses.add(address.getHostAddress());
+                }
+            }
+        } catch (SocketException e) {
+            e.printStackTrace();
+        }
+
+        return ipAddresses;
+    }
+
     private void startWebServer() {
         setupChromeDebugModeRealmJsContext();
         webServer = new AndroidWebServer(DEFAULT_PORT);