fix ipv6 localhost fetch (#4498)

* `node` null for localhost getaddrinfo

* more test

2 files changed, 31 insertions, 2 deletions

diff --git a/src/deps/uws.zig b/src/deps/uws.zig
index 201544a75..d3228141b 100644
--- a/src/deps/uws.zig
+++ b/src/deps/uws.zig
@@ -369,8 +369,17 @@ pub fn NewSocketHandler(comptime is_ssl: bool) type {
             debug("connect({s}, {d})", .{ host, port });
             var stack_fallback = std.heap.stackFallback(1024, bun.default_allocator);
             var allocator = stack_fallback.get();
-            var host_ = allocator.dupeZ(u8, host) catch return null;
-            defer allocator.free(host_);
+
+            var host_: ?[*:0]u8 = brk: {
+                // getaddrinfo expects `node` to be null if localhost
+                if (host.len < 6 and (bun.strings.eqlComptime(host, "[::1]") or bun.strings.eqlComptime(host, "[::]"))) {
+                    break :brk null;
+                }
+
+                break :brk allocator.dupeZ(u8, host) catch return null;
+            };
+
+            defer if (host_) |host__| allocator.free(host__[0..host.len]);
 
             var socket = us_socket_context_connect(comptime ssl_int, socket_ctx, host_, port, null, 0, @sizeOf(*anyopaque)) orelse return null;
             const socket_ = ThisSocket{ .socket = socket };
diff --git a/test/js/web/fetch/fetch.test.ts b/test/js/web/fetch/fetch.test.ts
index 59847dde9..aa44ee76a 100644
--- a/test/js/web/fetch/fetch.test.ts
+++ b/test/js/web/fetch/fetch.test.ts
@@ -531,6 +531,26 @@ describe("fetch", () => {
     expect(response2.status).toBe(200);
     expect(await response2.text()).toBe("0");
   });
+
+  it("should work with ipv6 localhost", async () => {
+    const server = Bun.serve({
+      port: 0,
+      fetch(req) {
+        return new Response("Pass!");
+      },
+    });
+
+    let res = await fetch(`http://[::1]:${server.port}`);
+    expect(await res.text()).toBe("Pass!");
+    res = await fetch(`http://[::]:${server.port}/`);
+    expect(await res.text()).toBe("Pass!");
+    res = await fetch(`http://[0:0:0:0:0:0:0:1]:${server.port}/`);
+    expect(await res.text()).toBe("Pass!");
+    res = await fetch(`http://[0000:0000:0000:0000:0000:0000:0000:0001]:${server.port}/`);
+    expect(await res.text()).toBe("Pass!");
+
+    server.stop();
+  });
 });
 
 it("simultaneous HTTPS fetch", async () => {