3 files changed, 164 insertions, 0 deletions
diff --git a/pkg/tcpip/testutil/BUILD b/pkg/tcpip/testutil/BUILD
new file mode 100644
index 000000000..472545a5d
--- /dev/null
+++ b/pkg/tcpip/testutil/BUILD
@@ -0,0 +1,18 @@
+load("//tools:defs.bzl", "go_library", "go_test")
+
+package(licenses = ["notice"])
+
+go_library(
+    name = "testutil",
+    testonly = True,
+    srcs = ["testutil.go"],
+    visibility = ["//visibility:public"],
+    deps = ["//pkg/tcpip"],
+)
+
+go_test(
+    name = "testutil_test",
+    srcs = ["testutil_test.go"],
+    library = ":testutil",
+    deps = ["//pkg/tcpip"],
+)
diff --git a/pkg/tcpip/testutil/testutil.go b/pkg/tcpip/testutil/testutil.go
new file mode 100644
index 000000000..1aaed590f
--- /dev/null
+++ b/pkg/tcpip/testutil/testutil.go
@@ -0,0 +1,43 @@
+// Copyright 2021 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package testutil provides helper functions for netstack unit tests.
+package testutil
+
+import (
+	"fmt"
+	"net"
+
+	"gvisor.dev/gvisor/pkg/tcpip"
+)
+
+// MustParse4 parses an IPv4 string (e.g. "192.168.1.1") into a tcpip.Address.
+// Passing an IPv4-mapped IPv6 address will yield only the 4 IPv4 bytes.
+func MustParse4(addr string) tcpip.Address {
+	ip := net.ParseIP(addr).To4()
+	if ip == nil {
+		panic(fmt.Sprintf("Parse4 expects IPv4 addresses, but was passed %q", addr))
+	}
+	return tcpip.Address(ip)
+}
+
+// MustParse6 parses an IPv6 string (e.g. "fe80::1") into a tcpip.Address. Passing
+// an IPv4 address will yield an IPv4-mapped IPv6 address.
+func MustParse6(addr string) tcpip.Address {
+	ip := net.ParseIP(addr).To16()
+	if ip == nil {
+		panic(fmt.Sprintf("Parse6 was passed malformed address %q", addr))
+	}
+	return tcpip.Address(ip)
+}
diff --git a/pkg/tcpip/testutil/testutil_test.go b/pkg/tcpip/testutil/testutil_test.go
new file mode 100644
index 000000000..6aad9585d
--- /dev/null
+++ b/pkg/tcpip/testutil/testutil_test.go
@@ -0,0 +1,103 @@
+// Copyright 2021 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package testutil
+
+import (
+	"testing"
+
+	"gvisor.dev/gvisor/pkg/tcpip"
+)
+
+// Who tests the testutils?
+
+func TestMustParse4(t *testing.T) {
+	tcs := []struct {
+		str         string
+		addr        tcpip.Address
+		shouldPanic bool
+	}{
+		{
+			str:  "127.0.0.1",
+			addr: "\x7f\x00\x00\x01",
+		}, {
+			str:         "",
+			shouldPanic: true,
+		}, {
+			str:         "fe80::1",
+			shouldPanic: true,
+		}, {
+			// In an ideal world this panics too, but net.IP
+			// doesn't distinguish between IPv4 and IPv4-mapped
+			// addresses.
+			str:  "::ffff:0.0.0.1",
+			addr: "\x00\x00\x00\x01",
+		},
+	}
+
+	for _, tc := range tcs {
+		t.Run(tc.str, func(t *testing.T) {
+			if tc.shouldPanic {
+				defer func() {
+					if r := recover(); r == nil {
+						t.Errorf("panic expected, but did not occur")
+					}
+				}()
+			}
+			if got := MustParse4(tc.str); got != tc.addr {
+				t.Errorf("got MustParse4(%s) = %s, want = %s", tc.str, got, tc.addr)
+			}
+		})
+	}
+}
+
+func TestMustParse6(t *testing.T) {
+	tcs := []struct {
+		str         string
+		addr        tcpip.Address
+		shouldPanic bool
+	}{
+		{
+			// In an ideal world this panics too, but net.IP
+			// doesn't distinguish between IPv4 and IPv4-mapped
+			// addresses.
+			str:  "127.0.0.1",
+			addr: "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xff\xff\x7f\x00\x00\x01",
+		}, {
+			str:         "",
+			shouldPanic: true,
+		}, {
+			str:  "fe80::1",
+			addr: "\xfe\x80\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01",
+		}, {
+			str:  "::ffff:0.0.0.1",
+			addr: "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xff\xff\x00\x00\x00\x01",
+		},
+	}
+
+	for _, tc := range tcs {
+		t.Run(tc.str, func(t *testing.T) {
+			if tc.shouldPanic {
+				defer func() {
+					if r := recover(); r == nil {
+						t.Errorf("panic expected, but did not occur")
+					}
+				}()
+			}
+			if got := MustParse6(tc.str); got != tc.addr {
+				t.Errorf("got MustParse6(%s) = %s, want = %s", tc.str, got, tc.addr)
+			}
+		})
+	}
+}