odin-lang.Odin/tests/core/net/test_core_net.odin

/*
	Copyright 2021 Jeroen van Rijn <[email protected]>.
	Copyright 2024 Feoramund       <[email protected]>.
	Made available under Odin's BSD-3 license.

	List of contributors:
		Jeroen van Rijn: Initial implementation.
		graphitemaster:  pton/ntop IANA test vectors
		Feoramund:       FreeBSD-specific tests.

	A test suite for `core:net`
*/
#+build !netbsd
#+build !openbsd
#+feature dynamic-literals
package test_core_net

import "core:testing"
import "core:net"
import "core:strconv"
import "core:sync"
import "core:time"
import "core:thread"
import "core:fmt"
import "core:log"

@test
address_parsing_test :: proc(t: ^testing.T) {
	for vector in IP_Address_Parsing_Test_Vectors {
		kind := ""
		switch vector.family {
		case .IP4:     kind = "[IPv4]"
		case .IP4_Alt: kind = "[IPv4 Non-Decimal]"
		case .IP6:     kind = "[IPv6]"
		case: panic("Add support to the test for this type.")
		}

		valid := len(vector.binstr) > 0
		switch vector.family {
		case .IP4, .IP4_Alt:
			// Does `net.parse_ip4_address` think we parsed the address properly?
			non_decimal := vector.family == .IP4_Alt
			any_addr    := net.parse_address(vector.input, non_decimal)
			parsed_ok   := any_addr != nil
			parsed: net.IP4_Address

			// Ensure that `parse_address` doesn't parse IPv4 addresses into IPv6 addreses by mistake.
			switch addr in any_addr {
			case net.IP4_Address:
				parsed = addr
			case net.IP6_Address:
				parsed_ok = false
				testing.expectf(t, false, "parse_address mistook %v as IPv6 address %04x", vector.input, addr)
			}

			if !parsed_ok && valid {
				testing.expectf(t, parsed_ok == valid, "parse_ip4_address failed to parse %v, expected %v", vector.input, binstr_to_address(t, vector.binstr))

			} else if parsed_ok && !valid {
				testing.expectf(t, parsed_ok == valid, "parse_ip4_address parsed %v into %v, expected failure", vector.input, parsed)
			}

			if valid && parsed_ok {
				actual_binary := address_to_binstr(parsed)
				testing.expectf(t, actual_binary == vector.binstr, "parse_ip4_address parsed %v into %v, expected %v", vector.input, actual_binary, vector.binstr)

				// Do we turn an address back into the same string properly? No point in testing the roundtrip if the first part failed.
				if len(vector.output) > 0 && actual_binary == vector.binstr {
					stringified := net.address_to_string(parsed)
					testing.expectf(t, stringified == vector.output, "address_to_string turned %v into %v, expected %v", parsed, stringified, vector.output)
				}
			}

		case .IP6:
			// Do we parse the address properly?
			parsed, parsed_ok := net.parse_ip6_address(vector.input)

			if !parsed_ok && valid {
				testing.expectf(t, parsed_ok == valid, "parse_ip6_address failed to parse %v, expected %04x", vector.input, binstr_to_address(t, vector.binstr))

			} else if parsed_ok && !valid {
				testing.expectf(t, parsed_ok == valid, "parse_ip6_address parsed %v into %04x, expected failure", vector.input, parsed)
			}

			if valid && parsed_ok {
				actual_binary := address_to_binstr(parsed)
				testing.expectf(t, actual_binary == vector.binstr, "parse_ip6_address parsed %v into %v, expected %v", vector.input, actual_binary, vector.binstr)

				// Do we turn an address back into the same string properly? No point in testing the roundtrip if the first part failed.
				if len(vector.output) > 0 && actual_binary == vector.binstr {
					stringified := net.address_to_string(parsed)
					testing.expectf(t, stringified == vector.output, "address_to_string turned %v into %v, expected %v", parsed, stringified, vector.output)
				}
			}
		}
	}
}

Kind :: enum {
	IP4,     // Decimal IPv4
	IP4_Alt, // Non-decimal address
	IP6,     // Hex IPv6 or mixed IPv4/IPv6.
}

IP_Address_Parsing_Test_Vector :: struct {
	// Give it to the IPv4 or IPv6 parser?
	family:           Kind,

	// Input address to try and parse.
	input:            string,

	// Hexadecimal representation of the expected numeric value of the address. Zero length means input is invalid and the parser should report failure.
	binstr:           string,

	// Expected `address_to_string` output, if a valid input and this string is non-empty.
	output:           string,
}

IP_Address_Parsing_Test_Vectors :: []IP_Address_Parsing_Test_Vector{
	// dotted-decimal notation
	{ .IP4, "0.0.0.0",                 "00000000", "0.0.0.0"        },
	{ .IP4, "127.0.0.1",               "7f000001", "127.0.0.1"      },
	{ .IP4, "10.0.128.31",             "0a00801f", "10.0.128.31"    },
	{ .IP4, "255.255.255.255",         "ffffffff", "255.255.255.255"},

	// Odin custom: Address + port, valid
	{ .IP4, "0.0.0.0:80",              "00000000", "0.0.0.0"        },
	{ .IP4, "127.0.0.1:80",            "7f000001", "127.0.0.1"      },
	{ .IP4, "10.0.128.31:80",          "0a00801f", "10.0.128.31"    },
	{ .IP4, "255.255.255.255:80",      "ffffffff", "255.255.255.255"},

	{ .IP4, "[0.0.0.0]:80",            "00000000", "0.0.0.0"        },
	{ .IP4, "[127.0.0.1]:80",          "7f000001", "127.0.0.1"      },
	{ .IP4, "[10.0.128.31]:80",        "0a00801f", "10.0.128.31"    },
	{ .IP4, "[255.255.255.255]:80",    "ffffffff", "255.255.255.255"},

	// Odin custom: Address + port, invalid
	{ .IP4, "[]:80",                   "", ""},
	{ .IP4, "[0.0.0.0]",               "", ""},
	{ .IP4, "[127.0.0.1]:",            "", ""},
	{ .IP4, "[10.0.128.31] :80",       "", ""},
	{ .IP4, "[255.255.255.255]:65536", "", ""},


	// numbers-and-dots notation, but not dotted-decimal
	{ .IP4_Alt, "1.2.03.4",                "01020304", ""},
	{ .IP4_Alt, "1.2.0x33.4",              "01023304", ""},
	{ .IP4_Alt, "1.2.0XAB.4",              "0102ab04", ""},
	{ .IP4_Alt, "1.2.0xabcd",              "0102abcd", ""},
	{ .IP4_Alt, "1.0xabcdef",              "01abcdef", ""},
	{ .IP4_Alt, "0x01abcdef",              "01abcdef", ""},
	{ .IP4_Alt, "00377.0x0ff.65534",       "fffffffe", ""},

	// invalid as decimal address
	{ .IP4, "",                        "", ""},
	{ .IP4, ".1.2.3",                  "", ""},
	{ .IP4, "1..2.3",                  "", ""},
	{ .IP4, "1.2.3.",                  "", ""},
	{ .IP4, "1.2.3.4.5",               "", ""},
	{ .IP4, "1.2.3.a",                 "", ""},
	{ .IP4, "1.256.2.3",               "", ""},
	{ .IP4, "1.2.4294967296.3",        "", ""},
	{ .IP4, "1.2.-4294967295.3",       "", ""},
	{ .IP4, "1.2. 3.4",                "", ""},

	// invalid as non-decimal address
	{ .IP4_Alt, "",                        "", ""},
	{ .IP4_Alt, ".1.2.3",                  "", ""},
	{ .IP4_Alt, "1..2.3",                  "", ""},
	{ .IP4_Alt, "1.2.3.",                  "", ""},
	{ .IP4_Alt, "1.2.3.4.5",               "", ""},
	{ .IP4_Alt, "1.2.3.a",                 "", ""},
	{ .IP4_Alt, "1.256.2.3",               "", ""},
	{ .IP4_Alt, "1.2.4294967296.3",        "", ""},
	{ .IP4_Alt, "1.2.-4294967295.3",       "", ""},
	{ .IP4_Alt, "1.2. 3.4",                "", ""},

	// Valid IPv6 addresses
	{ .IP6, "::",                                            "00000000000000000000000000000000", "::"},
	{ .IP6, "::1",                                           "00000000000000000000000000000001", "::1"},
	{ .IP6, "::192.168.1.1",                                 "000000000000000000000000c0a80101", "::c0a8:101"},
	{ .IP6, "0000:0000:0000:0000:0000:ffff:255.255.255.255", "00000000000000000000ffffffffffff", "::ffff:ffff:ffff"},

	{ .IP6, "0:0:0:0:0:0:192.168.1.1", "000000000000000000000000c0a80101", "::c0a8:101"},
	{ .IP6, "0:0::0:0:0:192.168.1.1",  "000000000000000000000000c0a80101", "::c0a8:101"},
	{ .IP6, "::ffff:192.168.1.1",      "00000000000000000000ffffc0a80101", "::ffff:c0a8:101"},
	{ .IP6, "a:0b:00c:000d:E:F::",     "000a000b000c000d000e000f00000000", "a:b:c:d:e:f::"},
	{ .IP6, "1:2:3:4:5:6::",           "00010002000300040005000600000000", "1:2:3:4:5:6::"},
	{ .IP6, "1:2:3:4:5:6:7::",         "00010002000300040005000600070000", "1:2:3:4:5:6:7:0"},
	{ .IP6, "::1:2:3:4:5:6",           "00000000000100020003000400050006", "::1:2:3:4:5:6"},
	{ .IP6, "::1:2:3:4:5:6:7",         "00000001000200030004000500060007", "0:1:2:3:4:5:6:7"},
	{ .IP6, "a:b::c:d:e:f",            "000a000b00000000000c000d000e000f", "a:b::c:d:e:f"},
	{ .IP6, "0:0:0:0:0:ffff:c0a8:5e4", "00000000000000000000ffffc0a805e4", "::ffff:c0a8:5e4"},
	{ .IP6, "0::ffff:c0a8:5e4",        "00000000000000000000ffffc0a805e4", "::ffff:c0a8:5e4"},


	// If multiple zero runs are present, shorten the longest one.
	{ .IP6, "1:0:0:2:0:0:0:3",         "00010000000000020000000000000003", "1:0:0:2::3"},

	// Invalid IPv6 addresses
	{ .IP6, "",                        "", ""},
	{ .IP6, ":",                       "", ""},
	{ .IP6, ":::",                     "", ""},
	{ .IP6, "192.168.1.1",             "", ""},
	{ .IP6, ":192.168.1.1",            "", ""},
	{ .IP6, "::012.34.56.78",          "", ""},
	{ .IP6, ":ffff:192.168.1.1",       "", ""},
	{ .IP6, ".192.168.1.1",            "", ""},
	{ .IP6, ":.192.168.1.1",           "", ""},
	{ .IP6, "a:0b:00c:000d:0000e:f::", "", ""},
	{ .IP6, "1:2:3:4:5:6:7:8::",       "", ""},
	{ .IP6, "1:2:3:4:5:6:7::9",        "", ""},
	{ .IP6, "::1:2:3:4:5:6:7:8",       "", ""},
	{ .IP6, "ffff:c0a8:5e4",           "", ""},
	{ .IP6, ":ffff:c0a8:5e4",          "", ""},
	{ .IP6, "0:0:0:0:ffff:c0a8:5e4",   "", ""},
	{ .IP6, "::0::ffff:c0a8:5e4",      "", ""},
	{ .IP6, "c0a8",                    "", ""},
}

@(test)
two_servers_binding_same_endpoint :: proc(t: ^testing.T) {
	skt1, err1 := net.listen_tcp({address=net.IP4_Address{127, 0, 0, 1}, port=0})
	defer net.close(skt1)

	ep, perr := net.bound_endpoint(skt1)

	skt2, err2 := net.listen_tcp(ep)
	defer net.close(skt2)

	testing.expect(t, err1 == nil, "expected first server binding to endpoint to do so without error")
	testing.expect_value(t, perr, nil)
	testing.expect(t, err2 == net.Bind_Error.Address_In_Use, "expected second server to bind to an endpoint to return .Address_In_Use")
}

@(test)
client_sends_server_data :: proc(t: ^testing.T) {
	CONTENT: string: "Hellope!"

	SEND_TIMEOUT :: time.Duration(1 * time.Second)
	RECV_TIMEOUT :: time.Duration(1 * time.Second)

	@static endpoint: net.Endpoint
	endpoint.address = net.IP4_Address{127, 0, 0, 1}

	Thread_Data :: struct {
		t: ^testing.T,
		skt: net.Any_Socket,
		err: net.Network_Error,
		tid: ^thread.Thread,

		data:   [1024]u8, // Received data and its length
		length: int,
		wg:     ^sync.Wait_Group,
	}

	tcp_client :: proc(thread_data: rawptr) {
		r := cast(^Thread_Data)thread_data

		defer sync.wait_group_done(r.wg)

		if r.skt, r.err = net.dial_tcp(endpoint); r.err != nil {
			testing.expectf(r.t, false, "[tcp_client:dial_tcp] %v", r.err)
			return
		}

		net.set_option(r.skt, .Send_Timeout, SEND_TIMEOUT)

		_, r.err = net.send(r.skt, transmute([]byte)CONTENT)
	}

	tcp_server :: proc(thread_data: rawptr) {
		r := cast(^Thread_Data)thread_data

		defer sync.wait_group_done(r.wg)

		if r.skt, r.err = net.listen_tcp(endpoint); r.err != nil {
			sync.wait_group_done(r.wg)
			testing.expectf(r.t, false, "[tcp_server:listen_tcp] %v", r.err)
			return
		}

		endpoint, r.err = net.bound_endpoint(r.skt.(net.TCP_Socket))
		if !testing.expect_value(r.t, r.err, nil) {
			return
		}

		sync.wait_group_done(r.wg)

		client: net.TCP_Socket
		if client, _, r.err = net.accept_tcp(r.skt.(net.TCP_Socket)); r.err != nil {
			testing.expectf(r.t, false, "[tcp_server:accept_tcp] %v", r.err)
			return
		}
		defer net.close(client)

		net.set_option(client, .Receive_Timeout, RECV_TIMEOUT)

		r.length, r.err = net.recv_tcp(client, r.data[:])
		return
	}
	
	thread_data := [2]Thread_Data{}

	wg: sync.Wait_Group
	sync.wait_group_add(&wg, 1)

	thread_data[0].t = t
	thread_data[0].wg = &wg
	thread_data[0].tid = thread.create_and_start_with_data(&thread_data[0], tcp_server, context)
	
	sync.wait_group_wait(&wg)
	sync.wait_group_add(&wg, 2)

	thread_data[1].t = t
	thread_data[1].wg = &wg
	thread_data[1].tid = thread.create_and_start_with_data(&thread_data[1], tcp_client, context)

	defer {
		net.close(thread_data[0].skt)
		thread.destroy(thread_data[0].tid)

		net.close(thread_data[1].skt)
		thread.destroy(thread_data[1].tid)
	}
	sync.wait_group_wait(&wg)

	okay := thread_data[0].err == nil && thread_data[1].err == nil
	testing.expectf(t, okay, "Expected client and server to return `nil`, got %v and %v", thread_data[0].err, thread_data[1].err)

	received := string(thread_data[0].data[:thread_data[0].length])

	okay  = received == CONTENT
	testing.expectf(t, okay, "Expected client to send \"{}\", got \"{}\"", CONTENT, received)
}

URL_Test :: struct {
	scheme, host, path: string,
	queries: map[string]string,
	fragment: string,
	url: []string,
}

@test
split_url_test :: proc(t: ^testing.T) {
	test_cases := []URL_Test{
		{
			"http", "example.com", "/",
			{}, "",
			{"http://example.com"},
		},
		{
			"https", "odin-lang.org", "/",
			{}, "",
			{"https://odin-lang.org"},
		},
		{
			"https", "odin-lang.org", "/docs/",
			{}, "",
			{"https://odin-lang.org/docs/"},
		},
		{
			"https", "odin-lang.org", "/docs/overview",
			{}, "",
			{"https://odin-lang.org/docs/overview"},
		},
		{
			"http", "example.com", "/",
			{"a" = "b"}, "",
			{"http://example.com?a=b"},
		},
		{
			"http", "example.com", "/",
			{"a" = ""}, "",
			{"http://example.com?a"},
		},
		{
			"http", "example.com", "/",
			{"a" = "b", "c" = "d"}, "",
			{"http://example.com?a=b&c=d"},
		},
		{
			"http", "example.com", "/",
			{"a" = "", "c" = "d"}, "",
			{"http://example.com?a&c=d"},
		},
		{
			"http", "example.com", "/example",
			{"a" = "", "b" = ""}, "",
			{"http://example.com/example?a&b"},
		},
		{
			"https", "example.com", "/callback",
			{"redirect" = "https://other.com/login"}, "",
			{"https://example.com/callback?redirect=https://other.com/login"},
		},
		{
			"http", "example.com", "/",
			{}, "Hellope",
			{"http://example.com#Hellope"},
		},
		{
			"https", "odin-lang.org", "/",
			{"a" = ""}, "Hellope",
			{"https://odin-lang.org?a#Hellope"},
		},
		{
			"http", "example.com", "/",
			{"a" = "b"}, "BeesKnees",
			{"http://example.com?a=b#BeesKnees"},
		},
		{
			"https", "odin-lang.org", "/docs/overview/",
			{}, "hellope",
			{"https://odin-lang.org/docs/overview/#hellope"},
		},
	}

	for test in test_cases {
		scheme, host, path, queries, fragment := net.split_url(test.url[0])
		defer {
			delete(queries)
			delete(test.queries)
		}

		testing.expectf(t, scheme       == test.scheme,       "Expected `net.split_url` to return %s, got %s", test.scheme, scheme)
		testing.expectf(t, host         == test.host,         "Expected `net.split_url` to return %s, got %s", test.host, host)
		testing.expectf(t, path         == test.path,         "Expected `net.split_url` to return %s, got %s", test.path, path)
		testing.expectf(t, len(queries) == len(test.queries), "Expected `net.split_url` to return %d queries, got %d queries", len(test.queries), len(queries))
		for k, v in queries {
			expected := test.queries[k]
			testing.expectf(t, v == expected, "Expected `net.split_url` to return %s, got %s", expected, v)
		}
		testing.expectf(t, fragment == test.fragment, "Expected `net.split_url` to return %s, got %s", test.fragment, fragment)
	}
}


@test
join_url_test :: proc(t: ^testing.T) {
	test_cases := []URL_Test{
		{
			"http", "example.com", "/",
			{}, "",
			{"http://example.com/"},
		},
		{
			"https", "odin-lang.org", "/",
			{}, "",
			{"https://odin-lang.org/"},
		},
		{
			"https", "odin-lang.org", "/docs/",
			{}, "",
			{"https://odin-lang.org/docs/"},
		},
		{
			"https", "odin-lang.org", "/docs/overview",
			{}, "",
			{"https://odin-lang.org/docs/overview"},
		},
		{
			"http", "example.com", "/",
			{"a" = "b"}, "",
			{"http://example.com/?a=b"},
		},
		{
			"http", "example.com", "/",
			{"a" = ""}, "",
			{"http://example.com/?a"},
		},
		{
			"http", "example.com", "/",
			{"a" = "b", "c" = "d"}, "",
			{"http://example.com/?a=b&c=d", "http://example.com/?c=d&a=b"},
		},
		{
			"http", "example.com", "/",
			{"a" = "", "c" = "d"}, "",
			{"http://example.com/?a&c=d", "http://example.com/?c=d&a"},
		},
		{
			"http", "example.com", "/example",
			{"a" = "", "b" = ""}, "",
			{"http://example.com/example?a&b", "http://example.com/example?b&a"},
		},
		{
			"http", "example.com", "/",
			{}, "Hellope",
			{"http://example.com/#Hellope"},
		},
		{
			"https", "odin-lang.org", "/",
			{"a" = ""}, "Hellope",
			{"https://odin-lang.org/?a#Hellope"},
		},
		{
			"http", "example.com", "/",
			{"a" = "b"}, "BeesKnees",
			{"http://example.com/?a=b#BeesKnees"},
		},
		{
			"https", "odin-lang.org", "/docs/overview/",
			{}, "hellope",
			{"https://odin-lang.org/docs/overview/#hellope"},
		},
	}

	for test in test_cases {
		url := net.join_url(test.scheme, test.host, test.path, test.queries, test.fragment)
		defer {
			delete(url)
			delete(test.queries)
		}
		pass := false
		for test_url in test.url {
			pass |= url == test_url
		}
		testing.expectf(t, pass, "Expected `net.join_url` to return one of %s, got %s", test.url, url)
	}
}

@test
test_udp_echo :: proc(t: ^testing.T) {
	endpoint := net.Endpoint{address=net.IP4_Address{127, 0, 0, 1}, port=0}

	server, make_server_err := net.make_unbound_udp_socket(.IP4)
	if !testing.expect_value(t, make_server_err, nil) {
		return
	}
	defer net.close(server)

	bind_server_err := net.bind(server, endpoint)
	if !testing.expect_value(t, bind_server_err, nil) {
		return
	}

	perr: net.Network_Error
	endpoint, perr = net.bound_endpoint(server)
	if !testing.expect_value(t, perr, nil) {
		return
	}

	client, make_client_err := net.make_unbound_udp_socket(.IP4)
	if !testing.expect_value(t, make_client_err, nil) {
		return
	}
	defer net.close(client)

	msg := "Hellope world!"
	buf: [64]u8

	bytes_written, send_err := net.send_udp(client, transmute([]u8)msg[:], endpoint)
	if !testing.expect_value(t, send_err, nil) {
		return
	}
	if !testing.expect_value(t, bytes_written, len(msg)) {
		return
	}

	bytes_read, _, read_err := net.recv_udp(server, buf[:])
	if !testing.expect_value(t, read_err, nil) {
		return
	}
	if !testing.expect_value(t, bytes_read, len(msg)) {
		return
	}

	testing.expect_value(t, msg, transmute(string)buf[:bytes_read])
}

@test
test_dns_resolve :: proc(t: ^testing.T) {
	// NOTE: This test depends on external factors, so if it fails, an IP
	// address may have changed or become unavailable.

	// The net API returns only one address per protocol version, and DNS
	// records can store many, so we'll have to check all possibilities.
	ep4, ep6, resolve_err := net.resolve("dns.quad9.net")
	if !testing.expect_value(t, resolve_err, nil) {
		return
	}

	ip4, ip4_ok := ep4.address.(net.IP4_Address)
	if !testing.expect(t, ip4_ok, "Unable to resolve IP4") {
		return
	}

	valid_ip4_a := net.IP4_Address{  9,   9,   9,   9}
	valid_ip4_b := net.IP4_Address{149, 112, 112, 112}
	if ip4 != valid_ip4_a && ip4 != valid_ip4_b {
		log.errorf("DNS resolved to invalid IP4: %v, expected %v or %v", ip4, valid_ip4_a, valid_ip4_b)
	}

	ip6, ip6_ok := ep6.address.(net.IP6_Address)
	if !testing.expect(t, ip6_ok, "Unable to resolve IP6") {
		return
	}

	valid_ip6_a := net.IP6_Address{0x2620, 0xfe, 0, 0, 0, 0, 0,    9}
	valid_ip6_b := net.IP6_Address{0x2620, 0xfe, 0, 0, 0, 0, 0, 0xfe}
	if ip6 != valid_ip6_a && ip6 != valid_ip6_b {
		log.errorf("DNS resolved to invalid IP6: %v, expected %v or %v", ip6, valid_ip6_a, valid_ip6_b)
	}
}

@test
test_nonblocking_option :: proc(t: ^testing.T) {
	server, listen_err := net.listen_tcp({address=net.IP4_Address{127, 0, 0, 1}, port=0})
	if !testing.expect_value(t, listen_err, nil) {
		return
	}
	defer net.close(server)

	testing.set_fail_timeout(t, 2 * time.Second)

	// If the nonblocking option isn't set correctly in the operating system,
	// this should block until the timeout hits.
	net.set_blocking(server, false)

	_, _, accept_err := net.accept_tcp(server)
	if !testing.expect_value(t, accept_err, net.Accept_Error.Would_Block) {
		return
	}
}

@(private)
address_to_binstr :: proc(address: net.Address) -> (binstr: string) {
	switch t in address {
	case net.IP4_Address:
		b := transmute(u32be)t
		return fmt.tprintf("%08x", b)
	case net.IP6_Address:
		b := transmute(u128be)t
		return fmt.tprintf("%32x", b)
	case:
		return ""
	}
	unreachable()
}

@(private)
binstr_to_address :: proc(t: ^testing.T, binstr: string) -> (address: net.Address) {
	switch len(binstr) {
	case 8:  // IPv4
		a, ok := strconv.parse_u64_of_base(binstr, 16)
		testing.expect(t, ok, "failed to parse test case bin string")

		ipv4 := u32be(a)
		return net.IP4_Address(transmute([4]u8)ipv4)


	case 32: // IPv6
		a, ok := strconv.parse_u128_of_base(binstr, 16)
		testing.expect(t, ok, "failed to parse test case bin string")

		ipv4 := u128be(a)
		return net.IP6_Address(transmute([8]u16be)ipv4)

	case 0:
		return nil
	}
	panic("Invalid test case")
}