Android API level <= 25 fails sendmsg ECN with InvalidInput

[mxinden]

When running the quinn-udp ecn_* unit tests sendmsg fails with:

2024-08-22T14:41:30.636494Z  WARN quinn_udp: sendmsg error: Os { code: 22, kind: InvalidInput, message: "Invalid argument" }, Transmit: { destination: 127.0.0.1:50196, src_ip: None, enc: Some(Ect0), len: 5, segment_size: None }

quinn/quinn-udp/tests/tests.rs

Lines 34 to 153 in cef42cc

	#[test]
	fn ecn_v6() {
	let send = Socket::from(UdpSocket::bind("[::1]:0").unwrap());
	let recv = Socket::from(UdpSocket::bind("[::1]:0").unwrap());
	for codepoint in [EcnCodepoint::Ect0, EcnCodepoint::Ect1] {
	test_send_recv(
	&send,
	&recv,
	Transmit {
	destination: recv.local_addr().unwrap().as_socket().unwrap(),
	ecn: Some(codepoint),
	contents: b"hello",
	segment_size: None,
	src_ip: None,
	},
	);
	}
	}
	#[test]
	#[cfg(not(any(target_os = "openbsd", target_os = "netbsd", target_os = "solaris")))]
	fn ecn_v4() {
	let send = Socket::from(UdpSocket::bind("127.0.0.1:0").unwrap());
	let recv = Socket::from(UdpSocket::bind("127.0.0.1:0").unwrap());
	for codepoint in [EcnCodepoint::Ect0, EcnCodepoint::Ect1] {
	test_send_recv(
	&send,
	&recv,
	Transmit {
	destination: recv.local_addr().unwrap().as_socket().unwrap(),
	ecn: Some(codepoint),
	contents: b"hello",
	segment_size: None,
	src_ip: None,
	},
	);
	}
	}
	#[test]
	#[cfg(not(any(target_os = "openbsd", target_os = "netbsd", target_os = "solaris")))]
	fn ecn_v6_dualstack() {
	let recv = socket2::Socket::new(
	socket2::Domain::IPV6,
	socket2::Type::DGRAM,
	Some(socket2::Protocol::UDP),
	)
	.unwrap();
	recv.set_only_v6(false).unwrap();
	// We must use the unspecified address here, rather than a local address, to support dual-stack
	// mode
	recv.bind(&socket2::SockAddr::from(
	"[::]:0".parse::<SocketAddr>().unwrap(),
	))
	.unwrap();
	let recv_v6 = SocketAddr::V6(SocketAddrV6::new(
	Ipv6Addr::LOCALHOST,
	recv.local_addr().unwrap().as_socket().unwrap().port(),
	0,
	0,
	));
	let recv_v4 = SocketAddr::V4(SocketAddrV4::new(Ipv4Addr::LOCALHOST, recv_v6.port()));
	for (src, dst) in [("[::1]:0", recv_v6), ("127.0.0.1:0", recv_v4)] {
	dbg!(src, dst);
	let send = UdpSocket::bind(src).unwrap();
	let send = Socket::from(send);
	for codepoint in [EcnCodepoint::Ect0, EcnCodepoint::Ect1] {
	test_send_recv(
	&send,
	&recv,
	Transmit {
	destination: dst,
	ecn: Some(codepoint),
	contents: b"hello",
	segment_size: None,
	src_ip: None,
	},
	);
	}
	}
	}
	#[test]
	#[cfg(not(any(target_os = "openbsd", target_os = "netbsd", target_os = "solaris")))]
	fn ecn_v4_mapped_v6() {
	let send = socket2::Socket::new(
	socket2::Domain::IPV6,
	socket2::Type::DGRAM,
	Some(socket2::Protocol::UDP),
	)
	.unwrap();
	send.set_only_v6(false).unwrap();
	send.bind(&socket2::SockAddr::from(
	"[::]:0".parse::<SocketAddr>().unwrap(),
	))
	.unwrap();
	let recv = UdpSocket::bind("127.0.0.1:0").unwrap();
	let recv = Socket::from(recv);
	let recv_v4_mapped_v6 = SocketAddr::V6(SocketAddrV6::new(
	Ipv4Addr::LOCALHOST.to_ipv6_mapped(),
	recv.local_addr().unwrap().as_socket().unwrap().port(),
	0,
	0,
	));
	for codepoint in [EcnCodepoint::Ect0, EcnCodepoint::Ect1] {
	test_send_recv(
	&send,
	&recv,
	Transmit {
	destination: recv_v4_mapped_v6,
	ecn: Some(codepoint),
	contents: b"hello",
	segment_size: None,
	src_ip: None,
	},
	);
	}
	}

---

I don't have a fix (yet). Opening this early to publish the reproducer. See failing CI.

Any ideas anyone?

Depends on #1973.