1 files changed, 99 insertions, 0 deletions
diff --git a/src/runtime/internal/wasitest/tcpecho_test.go b/src/runtime/internal/wasitest/tcpecho_test.go
new file mode 100644
index 0000000..1137395
--- /dev/null
+++ b/src/runtime/internal/wasitest/tcpecho_test.go
@@ -0,0 +1,99 @@
+// Copyright 2023 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package wasi_test
+
+import (
+	"bytes"
+	"fmt"
+	"math/rand"
+	"net"
+	"os"
+	"os/exec"
+	"testing"
+	"time"
+)
+
+func TestTCPEcho(t *testing.T) {
+	if target != "wasip1/wasm" {
+		t.Skip()
+	}
+
+	// We're unable to use port 0 here (let the OS choose a spare port).
+	// Although the WASM runtime accepts port 0, and the WASM module listens
+	// successfully, there's no way for this test to query the selected port
+	// so that it can connect to the WASM module. The WASM module itself
+	// cannot access any information about the socket due to limitations
+	// with WASI preview 1 networking, and the WASM runtimes do not log the
+	// port when you pre-open a socket. So, we probe for a free port here.
+	// Given there's an unavoidable race condition, the test is disabled by
+	// default.
+	if os.Getenv("GOWASIENABLERACYTEST") != "1" {
+		t.Skip("skipping WASI test with unavoidable race condition")
+	}
+	var host string
+	port := rand.Intn(10000) + 40000
+	for attempts := 0; attempts < 10; attempts++ {
+		host = fmt.Sprintf("127.0.0.1:%d", port)
+		l, err := net.Listen("tcp", host)
+		if err == nil {
+			l.Close()
+			break
+		}
+		port++
+	}
+
+	subProcess := exec.Command("go", "run", "./testdata/tcpecho.go")
+
+	subProcess.Env = append(os.Environ(), "GOOS=wasip1", "GOARCH=wasm")
+
+	switch os.Getenv("GOWASIRUNTIME") {
+	case "wazero":
+		subProcess.Env = append(subProcess.Env, "GOWASIRUNTIMEARGS=--listen="+host)
+	case "wasmtime", "":
+		subProcess.Env = append(subProcess.Env, "GOWASIRUNTIMEARGS=--tcplisten="+host)
+	default:
+		t.Skip("WASI runtime does not support sockets")
+	}
+
+	var b bytes.Buffer
+	subProcess.Stdout = &b
+	subProcess.Stderr = &b
+
+	if err := subProcess.Start(); err != nil {
+		t.Log(b.String())
+		t.Fatal(err)
+	}
+	defer subProcess.Process.Kill()
+
+	var conn net.Conn
+	var err error
+	for {
+		conn, err = net.Dial("tcp", host)
+		if err == nil {
+			break
+		}
+		time.Sleep(500 * time.Millisecond)
+	}
+	if err != nil {
+		t.Log(b.String())
+		t.Fatal(err)
+	}
+	defer conn.Close()
+
+	payload := []byte("foobar")
+	if _, err := conn.Write(payload); err != nil {
+		t.Fatal(err)
+	}
+	var buf [256]byte
+	n, err := conn.Read(buf[:])
+	if err != nil {
+		t.Fatal(err)
+	}
+	if string(buf[:n]) != string(payload) {
+		t.Error("unexpected payload")
+		t.Logf("expect: %d bytes (%v)", len(payload), payload)
+		t.Logf("actual: %d bytes (%v)", n, buf[:n])
+	}
+}