Fix EINVAL when setting IPv6 multicast membership (#17478)

packages/bun-usockets/src/bsd.c

@@ -408,7 +408,7 @@ static int bsd_socket_set_membership6(LIBUS_SOCKET_DESCRIPTOR fd, const struct s
         mreq.ipv6mr_interface = iface->sin6_scope_id;
     }
     int option = drop ? IPV6_LEAVE_GROUP : IPV6_JOIN_GROUP;
-    return setsockopt(fd, IPPROTO_IP, option, &mreq, sizeof(mreq));
+    return setsockopt(fd, IPPROTO_IPV6, option, &mreq, sizeof(mreq));
 }
 
 int bsd_socket_set_membership(LIBUS_SOCKET_DESCRIPTOR fd, const struct sockaddr_storage *addr, const struct sockaddr_storage *iface, int drop) {

src/bun.js/api/bun/udp_socket.zig

@@ -444,12 +444,12 @@ pub const UDPSocket = struct {
             return globalThis.throwInvalidArguments("Expected 1 argument, got {}", .{arguments.len});
         }
 
-        var addr: std.posix.sockaddr.storage = undefined;
+        var addr = std.mem.zeroes(std.posix.sockaddr.storage);
         if (!parseAddr(this, globalThis, JSC.jsNumber(0), arguments[0], &addr)) {
             return globalThis.throwValue(bun.JSC.Maybe(void).errnoSys(@as(i32, @intCast(@intFromEnum(std.posix.E.INVAL))), .setsockopt).?.toJS(globalThis));
         }
 
-        var interface: std.posix.sockaddr.storage = undefined;
+        var interface = std.mem.zeroes(std.posix.sockaddr.storage);
 
         const res = if (arguments.len > 1 and parseAddr(this, globalThis, JSC.jsNumber(0), arguments[1], &interface)) blk: {
             if (addr.family != interface.family) {

test/js/node/dgram/node-dgram.test.js

@@ -0,0 +1,53 @@
+import { describe, expect, it } from "bun:test";
+import * as dgram from "node:dgram";
+import { isWindows, isMacOS, isIPv6 } from "harness";
+
+describe.skipIf(!isIPv6())("node:dgram", () => {
+  it("adds membership successfully (IPv6)", () => {
+    const socket = makeSocket6();
+    socket.bind(0, () => {
+      socket.addMembership("ff01::1", getInterface());
+      if (!isMacOS) {
+        // macOS seems to be iffy with automatically choosing an interface.
+        socket.addMembership("ff02::1");
+      }
+    });
+  });
+
+  it("doesn't add membership given invalid inputs (IPv6)", () => {
+    const { promise, resolve, reject } = Promise.withResolvers();
+    const socket = makeSocket6();
+    socket.bind(0, () => {
+      expect(() => {
+        // fe00:: is not a valid multicast address
+        socket.addMembership("fe00::", getInterface());
+        reject();
+      }).toThrow();
+      expect(() => {
+        socket.addMembership("fe00::");
+        reject();
+      }).toThrow();
+      resolve();
+    });
+    return promise;
+  });
+});
+
+function makeSocket6() {
+  return dgram.createSocket({
+    type: "udp6",
+    ipv6Only: true,
+  });
+}
+
+function getInterface() {
+  if (isWindows) {
+    return "::%1";
+  }
+
+  if (isMacOS) {
+    return "::%lo0";
+  }
+
+  return "::%lo";
+}