feat: Implement simultaneous DNS resolution (#19)

feat: Implement simultaneous DNS resolution to address scenarios where an IP version DNS could take too long to time out due to unavailability.

CHANGELOG.md

@@ -1,3 +1,21 @@
+# 0.0.8 (12–06-2024)
+
+### Improvements
+
+- Implement simultaneous DNS resolution to address scenarios where an IP version DNS could take too long to time out due to unavailability
+
+# 0.0.7 (3–05-2024)
+
+### Improvements
+
+- Add Privacy Manifest
+
+# 0.0.6 (07–04-2024)
+
+### Improvements
+
+- Use GET & HTTP version 1.1 for Cellular requests, and forcing IPv4 resolution before try IPv6
+
 # 0.0.5 (02–02-2024)
 
 ### Improvements

README.md

@@ -85,7 +85,7 @@ During the current phase of this project, we only support SPM. We have plans to
 dependencies: [
     .package(
         url: "https://github.com/twilio/twilio-verify-sna-ios.git",
-        .upToNextMajor(from: "0.0.7")
+        .upToNextMajor(from: "0.0.8")
     )
 ]
 ```

SNASources/CellularSession.m

@@ -51,8 +51,8 @@ - (CellularSessionResult * _Nonnull)performRequest:(NSURL * _Nonnull)url {
     sessionResult.status = CellularSessionUnexpectedError;
 
     // Stores any errors that occur during execution
-    OSStatus status;
-    
+    __block OSStatus status;
+
     // All local (cellular interface) IP addresses of this device.
     NSMutableArray<SocketAddress *> *localAddresses = [NSMutableArray array];
     // All remote IP addresses that we're trying to connect to.
@@ -103,7 +103,7 @@ - (CellularSessionResult * _Nonnull)performRequest:(NSURL * _Nonnull)url {
         ifaddrs = ifaddrs->ifa_next;
     }
 
-    struct addrinfo *addrinfoPointer;
+    __block struct addrinfo *addrinfoPointer;
     struct addrinfo *addrinfo;
 
     // Generate "hints" for the DNS lookup (namely, search for both IPv4 and IPv6 addresses)
@@ -127,12 +127,53 @@ - (CellularSessionResult * _Nonnull)performRequest:(NSURL * _Nonnull)url {
     DNSServiceRef sdRef = NULL;
     DNSServiceFlags flags = kDNSServiceFlagsTimeout; // Set flags as needed
 
-    status = cellular_getaddrinfo([[url host] UTF8String], service, &hints, &addrinfoPointer, sdRef, flags, kDNSServiceProtocol_IPv4);
+    dispatch_group_t group = dispatch_group_create();
+    dispatch_semaphore_t semaphore = dispatch_semaphore_create(0);
+    dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
+    __block BOOL resolutionCompleted = NO;
+    __block struct addrinfo *addrinfoIPv4 = NULL;
+    __block struct addrinfo *addrinfoIPv6 = NULL;
 
-    if (status || addrinfoPointer == NULL) {
-        // Retry DNS resolution with IPV6
-        status = cellular_getaddrinfo([[url host] UTF8String], service, &hints, &addrinfoPointer, sdRef, flags, kDNSServiceProtocol_IPv6);
-    }
+    // Start the IPv4 resolution
+    dispatch_group_async(group, queue, ^{
+        status = cellular_getaddrinfo([[url host] UTF8String], service, &hints, &addrinfoIPv4, sdRef, flags, kDNSServiceProtocol_IPv4);
+        if (status == 0 && addrinfoIPv4 != NULL) {
+            @synchronized (semaphore) {
+                if (!resolutionCompleted) {
+                    addrinfoPointer = addrinfoIPv4;
+                    resolutionCompleted = YES;
+                    dispatch_semaphore_signal(semaphore);
+                }
+            }
+        }
+    });
+
+    // Start the IPv6 resolution
+    dispatch_group_async(group, queue, ^{
+        status = cellular_getaddrinfo([[url host] UTF8String], service, &hints, &addrinfoIPv6, sdRef, flags, kDNSServiceProtocol_IPv6);
+        if (status == 0 && addrinfoIPv6 != NULL) {
+            @synchronized (semaphore) {
+                if (!resolutionCompleted) {
+                    addrinfoPointer = addrinfoIPv6;
+                    resolutionCompleted = YES;
+                    dispatch_semaphore_signal(semaphore);
+                }
+            }
+        }
+    });
+
+    // Wait for the first resolution to complete
+    dispatch_semaphore_wait(semaphore, DISPATCH_TIME_FOREVER);
+
+    // Clean up the other addrinfo if it was also resolved
+    dispatch_group_notify(group, dispatch_get_main_queue(), ^{
+        if (addrinfoIPv4 && addrinfoIPv4 != addrinfoPointer) {
+            freeaddrinfo(addrinfoIPv4);
+        }
+        if (addrinfoIPv6 && addrinfoIPv6 != addrinfoPointer) {
+            freeaddrinfo(addrinfoIPv6);
+        }
+    });
 
     if (status || addrinfoPointer == NULL) {
         freeifaddrs(ifaddrPointer);

Sources/TwilioVerifySNAConfig.swift

@@ -20,5 +20,5 @@
 import Foundation
 
 public struct TwilioVerifySNAConfig {
-    public static let version = "0.0.7"
+    public static let version = "0.0.8"
 }

TwilioVerifySNADemo/Screens/PhoneNumber/PhoneNumberViewController.swift

@@ -398,4 +398,4 @@ extension PhoneNumberViewController {
 }
 
 /// Not required for the SDK implementation.
-private let sampleAppVersion = "0.0.7"
+private let sampleAppVersion = "0.0.8"

TwilioVerifySNADemo/TwilioVerifySNADemo.xcodeproj/project.pbxproj

@@ -417,7 +417,7 @@
 					"@executable_path/Frameworks",
 				);
 				MACOSX_DEPLOYMENT_TARGET = 12.0;
-				MARKETING_VERSION = 0.0.7;
+				MARKETING_VERSION = 0.0.8;
 				PRODUCT_BUNDLE_IDENTIFIER = com.twilio.TwilioVerifySNADemo;
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				PROVISIONING_PROFILE_SPECIFIER = "";
@@ -448,7 +448,7 @@
 					"@executable_path/Frameworks",
 				);
 				MACOSX_DEPLOYMENT_TARGET = 12.0;
-				MARKETING_VERSION = 0.0.7;
+				MARKETING_VERSION = 0.0.8;
 				PRODUCT_BUNDLE_IDENTIFIER = com.twilio.TwilioVerifySNADemo;
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				PROVISIONING_PROFILE_SPECIFIER = "";