From 47d96ab8adf0bb72e8070ea9d41e4a782f35f362 Mon Sep 17 00:00:00 2001
From: Patrick Wyatt <pat@codeofhonor.com>
Date: Wed, 29 Apr 2026 21:44:41 -0700
Subject: [PATCH] Display actual port when binding --port 0

This change causes lightpanda to display the actual port number (instead of 0)
when binding a dynamic port (--port 0), which makes automating based on
scraping lightpanda output simple.
---
 src/Server.zig          | 5 +++--
 src/network/Network.zig | 9 ++++++++-
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/src/Server.zig b/src/Server.zig
index 50f81d8a..d99347dc 100644
--- a/src/Server.zig
+++ b/src/Server.zig
@@ -57,8 +57,9 @@ pub fn init(app: *App, address: net.Address) !*Server {
         .clients_pool = std.heap.MemoryPool(Client).init(allocator),
     };
 
-    try self.app.network.bind(address, self, onAccept);
-    log.info(.app, "server running", .{ .address = address });
+    var bound_address = address;
+    try self.app.network.bind(&bound_address, self, onAccept);
+    log.info(.app, "server running", .{ .address = bound_address });
 
     return self;
 }
diff --git a/src/network/Network.zig b/src/network/Network.zig
index 42756783..4057641c 100644
--- a/src/network/Network.zig
+++ b/src/network/Network.zig
@@ -351,7 +351,7 @@ pub fn deinit(self: *Network) void {
 
 pub fn bind(
     self: *Network,
-    address: net.Address,
+    address: *net.Address,
     ctx: *anyopaque,
     on_accept: *const fn (ctx: *anyopaque, socket: posix.socket_t) void,
 ) !void {
@@ -367,6 +367,13 @@ pub fn bind(
     try posix.bind(listener, &address.any, address.getOsSockLen());
     try posix.listen(listener, self.config.maxPendingConnections());
 
+    // When the caller requests port 0, the OS assigns an ephemeral port; read
+    // the actual bound address back so callers (e.g. logging) see the real port.
+    var bound: posix.sockaddr.storage = undefined;
+    var bound_len: posix.socklen_t = @sizeOf(posix.sockaddr.storage);
+    try posix.getsockname(listener, @ptrCast(&bound), &bound_len);
+    address.* = net.Address.initPosix(@ptrCast(@alignCast(&bound)));
+
     if (self.listener != null) return error.TooManyListeners;
 
     self.listener = .{