Fix ObjC build error and add server socket API demo coverage by Copilot · Pull Request #7 · dustturtle/NWAsyncSocket

Copilot · 2026-03-04T08:33:54Z

CI ObjC Demo (macOS) job fails due to a compilation error in GCDAsyncSocket.m. The new server-side APIs (acceptOnPort:, acceptOnInterface:port:, acceptOnUrl:) also lacked any test/demo coverage.

Build fixes

nw_endpoint_get_port return type: API returns uint16_t, not const char *. Removed incorrect pointer assignment and strtoul parsing.
isListening atomicity mismatch: Class extension declared nonatomic but public header declared atomic readonly. Aligned to atomic.

Server socket API demo (demo 6)

Added DemoSocketDelegate support for socket:didAcceptNewSocket: and a new interactive demo exercising all server-side APIs:

acceptOnPort: with port 0 (system-assigned)
Double-accept error handling
Client→Server loopback connection verifying didAcceptNewSocket: callback
disconnect stops listener, isListening → NO
acceptOnInterface:port: on localhost
acceptOnUrl: Unix Domain Socket
acceptOnUrl: non-file URL rejection

CI

Updated demo.yml ObjC runner input to include the new demo option.

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Implement acceptOnPort:error:, acceptOnInterface:port:error:, and acceptOnUrl:error: using Network.framework's nw_listener_t. Add socket:didAcceptNewSocket: delegate callback, isListening property, and proper listener cleanup in disconnect/dealloc. Co-authored-by: dustturtle <2305214+dustturtle@users.noreply.github.com>

…te sharing - Use unix:// scheme for nw_endpoint_create_url instead of file:// URL - Add comments explaining delegate sharing matches GCDAsyncSocket behavior Co-authored-by: dustturtle <2305214+dustturtle@users.noreply.github.com>

…istening atomicity - nw_endpoint_get_port() returns uint16_t, not const char*; remove incorrect pointer assignment and string conversion - Change isListening from nonatomic to atomic in class extension to match the atomic readonly declaration in the public header Co-authored-by: dustturtle <2305214+dustturtle@users.noreply.github.com>

…nterface, acceptOnUrl tests - Add didAcceptNewSocket: delegate to DemoSocketDelegate - Demo 6a: acceptOnPort: with port 0 (system-assigned) - Demo 6b: Double-accept error handling - Demo 6c: Client→Server connection, verify didAcceptNewSocket: - Demo 6d: Disconnect server, verify listener stops - Demo 6e: acceptOnInterface:port: on localhost - Demo 6f: acceptOnUrl: Unix Domain Socket - Demo 6g: acceptOnUrl: non-file URL error rejection - Update CI workflow for new demo option Co-authored-by: dustturtle <2305214+dustturtle@users.noreply.github.com>

Co-authored-by: dustturtle <2305214+dustturtle@users.noreply.github.com>

Copilot

Pull request overview

This PR fixes an Objective-C compilation issue in GCDAsyncSocket.m and expands the ObjC demo/CI coverage to exercise the new server-side accept/listen APIs (including TCP, interface-bound TCP, and Unix Domain Sockets).

Changes:

Fix Network.framework port handling by treating nw_endpoint_get_port() as uint16_t and align isListening property atomicity with the public header.
Implement server socket APIs (acceptOnPort:, acceptOnInterface:port:, acceptOnUrl:) and add delegate callback support for accepted connections.
Add a new ObjC demo (demo 6) and update CI workflow input to run it as part of “run all demos”.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
ObjC/ObjCDemo/main.m	Adds a new interactive demo (6) to exercise server/listener APIs and acceptance callback behavior.
ObjC/NWAsyncSocketObjC/include/GCDAsyncSocketDelegate.h	Adds optional `socket:didAcceptNewSocket:` delegate API and documents retention requirement.
ObjC/NWAsyncSocketObjC/include/GCDAsyncSocket.h	Exposes `isListening` and documents server accept APIs in the public interface.
ObjC/NWAsyncSocketObjC/GCDAsyncSocket.m	Implements listener lifecycle, accept APIs, disconnect behavior updates, and fixes port type usage.
.github/workflows/demo.yml	Updates scripted stdin to include the new demo in CI “run all demos”.

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Copilot · 2026-03-04T09:12:58Z

ObjC/NWAsyncSocketObjC/GCDAsyncSocket.m

+#if NW_FRAMEWORK_AVAILABLE
+        // Stop listener if in server mode
+        if (strongSelf.listener) {
+            nw_listener_cancel(strongSelf.listener);
+            strongSelf.listener = nil;
+            strongSelf.isListening = NO;
+            strongSelf.localPort = 0;
+        }
+#endif


disconnect cancels and nils listener (and sets isListening = NO) before calling disconnectInternalWithError:. This can make disconnectInternalWithError: hit its early-return guard for a listen-only socket, skipping state reset and socketDidDisconnect:withError:. Consider removing the pre-cancel block here and letting disconnectInternalWithError: handle listener cancellation/cleanup (or avoid clearing listener/isListening before calling into it).

Suggested change

#if NW_FRAMEWORK_AVAILABLE

// Stop listener if in server mode

if (strongSelf.listener) {

nw_listener_cancel(strongSelf.listener);

strongSelf.listener = nil;

strongSelf.isListening = NO;

strongSelf.localPort = 0;

}

#endif

Copilot · 2026-03-04T09:12:58Z

ObjC/NWAsyncSocketObjC/GCDAsyncSocket.m

+- (BOOL)acceptOnInterface:(NSString *)interface port:(uint16_t)port error:(NSError **)errPtr {
+#if NW_FRAMEWORK_AVAILABLE
+    if (self.isListening) {
+        if (errPtr) {
+            *errPtr = [NSError errorWithDomain:GCDAsyncSocketErrorDomain
+                                          code:GCDAsyncSocketErrorAlreadyConnected
+                                      userInfo:@{NSLocalizedDescriptionKey: @"Socket is already listening."}];
+        }
+        return NO;
+    }
+


acceptOnInterface:port:error: only checks self.isListening to reject a second listen. During the window after self.listener is created but before the state handler sets isListening = YES, a second call can succeed and replace the listener. Also, calling accept while isConnected is true should be rejected. Consider guarding on (self.listener != NULL) || self.isListening || self.isConnected (and returning an appropriate error).

Copilot · 2026-03-04T09:12:58Z

ObjC/NWAsyncSocketObjC/GCDAsyncSocket.m

+- (BOOL)acceptOnUrl:(NSURL *)url error:(NSError **)errPtr {
+#if NW_FRAMEWORK_AVAILABLE
+    if (self.isListening) {
+        if (errPtr) {
+            *errPtr = [NSError errorWithDomain:GCDAsyncSocketErrorDomain
+                                          code:GCDAsyncSocketErrorAlreadyConnected
+                                      userInfo:@{NSLocalizedDescriptionKey: @"Socket is already listening."}];
+        }
+        return NO;
+    }
+


acceptOnUrl:error: only checks self.isListening to reject a second listen, but self.listener is assigned before isListening is flipped in the state handler. A second call during startup could incorrectly succeed and replace the listener. Also consider rejecting accept calls when isConnected is already true. Guarding on self.listener != NULL (and/or setting isListening immediately when listener creation succeeds) would make this robust.

Copilot · 2026-03-04T09:12:59Z

ObjC/NWAsyncSocketObjC/include/GCDAsyncSocket.h

 /// Whether the socket is currently disconnected.
 @property (atomic, readonly) BOOL isDisconnected;

+/// Whether the socket is currently listening for incoming connections (server mode).
+@property (atomic, readonly) BOOL isListening;
+


With the introduction of isListening, a socket that is listening shouldn’t generally report isDisconnected == YES. The current implementation in GCDAsyncSocket.m returns !isConnected only, which will read as disconnected while listening. Consider updating isDisconnected semantics to include !isListening (e.g. disconnected iff not connected and not listening).

Copilot · 2026-03-04T09:12:59Z

ObjC/ObjCDemo/main.m

+    printf("  Accepted sockets count: %lu (expected: 1)\n",
+           (unsigned long)delegate.acceptedSockets.count);
+    if (delegate.acceptedSockets.count > 0) {
+        GCDAsyncSocket *accepted = delegate.acceptedSockets[0];


acceptedSockets is mutated on delegateQueue in didAcceptNewSocket:, but here it’s read from the main thread without synchronization. Since NSMutableArray isn’t thread-safe this can race/crash intermittently. Consider reading acceptedSockets via dispatch_sync(queue, ...) (same queue as delegate callbacks) or otherwise synchronizing access.

Suggested change

printf(" Accepted sockets count: %lu (expected: 1)\n",

(unsigned long)delegate.acceptedSockets.count);

if (delegate.acceptedSockets.count > 0) {

GCDAsyncSocket *accepted = delegate.acceptedSockets[0];

// Access acceptedSockets on the same queue used for delegate callbacks

__block NSUInteger acceptedCount = 0;

__block GCDAsyncSocket *accepted = nil;

dispatch_sync(queue, ^{

acceptedCount = delegate.acceptedSockets.count;

if (acceptedCount > 0) {

accepted = delegate.acceptedSockets[0];

}

});

printf(" Accepted sockets count: %lu (expected: 1)\n",

(unsigned long)acceptedCount);

if (acceptedCount > 0 && accepted != nil) {

Copilot · 2026-03-04T09:12:59Z

ObjC/ObjCDemo/main.m

+    [clientSocket disconnect];
+    for (GCDAsyncSocket *s in delegate.acceptedSockets) {
+        [s disconnect];
+    }


Similar to the earlier count/index access: iterating delegate.acceptedSockets from the main thread can race with didAcceptNewSocket: appends on delegateQueue. Consider synchronizing (e.g. take a snapshot on delegateQueue and iterate that).

Initial plan

24cdc10

Copilot AI assigned Copilot and dustturtle Mar 4, 2026

Copilot started work on behalf of dustturtle March 4, 2026 08:33 View session

Copilot AI and others added 2 commits March 4, 2026 08:38

Copilot AI changed the title ~~[WIP] Add server socket support to Objective-C API~~ Add server socket support (nw_listener_t) to ObjC GCDAsyncSocket Mar 4, 2026

Copilot finished work on behalf of dustturtle March 4, 2026 08:42

Copilot started work on behalf of dustturtle March 4, 2026 08:45 View session

Copilot AI changed the title ~~Add server socket support (nw_listener_t) to ObjC GCDAsyncSocket~~ Fix ObjC build: nw_endpoint_get_port returns uint16_t, fix isListening atomicity Mar 4, 2026

Copilot finished work on behalf of dustturtle March 4, 2026 08:49

Copilot started work on behalf of dustturtle March 4, 2026 08:49 View session

Copilot AI and others added 2 commits March 4, 2026 08:57

Use PID-based unique filename for Unix domain socket in demo

89dc739

Co-authored-by: dustturtle <2305214+dustturtle@users.noreply.github.com>

Copilot AI changed the title ~~Fix ObjC build: nw_endpoint_get_port returns uint16_t, fix isListening atomicity~~ Fix ObjC build error and add server socket API demo coverage Mar 4, 2026

Copilot finished work on behalf of dustturtle March 4, 2026 08:59

dustturtle marked this pull request as ready for review March 4, 2026 09:04

Copilot AI review requested due to automatic review settings March 4, 2026 09:04

dustturtle merged commit 6d2e213 into main Mar 4, 2026
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Copilot AI reviewed Mar 4, 2026

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Fix ObjC build error and add server socket API demo coverage#7

Fix ObjC build error and add server socket API demo coverage#7
dustturtle merged 6 commits intomainfrom
copilot/add-server-socket-support

Copilot AI commented Mar 4, 2026 •

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-    printf("  Accepted sockets count: %lu (expected: 1)\n",
-           (unsigned long)delegate.acceptedSockets.count);
-    if (delegate.acceptedSockets.count > 0) {
-        GCDAsyncSocket *accepted = delegate.acceptedSockets[0];
+    // Access acceptedSockets on the same queue used for delegate callbacks
+    __block NSUInteger acceptedCount = 0;
+    __block GCDAsyncSocket *accepted = nil;
+    dispatch_sync(queue, ^{
+        acceptedCount = delegate.acceptedSockets.count;
+        if (acceptedCount > 0) {
+            accepted = delegate.acceptedSockets[0];
+        }
+    });
+    printf("  Accepted sockets count: %lu (expected: 1)\n",
+           (unsigned long)acceptedCount);
+    if (acceptedCount > 0 && accepted != nil) {

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Build fixes

Server socket API demo (demo 6)

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Copilot AI commented Mar 4, 2026 •

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