// 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 for { var err error conn, err = net.Dial("tcp", host) if err == nil { break } time.Sleep(500 * time.Millisecond) } 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]) } }