tcpecho_test.go

     1  // Copyright 2023 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package wasi_test
     6  
     7  import (
     8  	"bytes"
     9  	"fmt"
    10  	"math/rand"
    11  	"net"
    12  	"os"
    13  	"os/exec"
    14  	"testing"
    15  	"time"
    16  )
    17  
    18  func TestTCPEcho(t *testing.T) {
    19  	if target != "wasip1/wasm" {
    20  		t.Skip()
    21  	}
    22  
    23  	// We're unable to use port 0 here (let the OS choose a spare port).
    24  	// Although the WASM runtime accepts port 0, and the WASM module listens
    25  	// successfully, there's no way for this test to query the selected port
    26  	// so that it can connect to the WASM module. The WASM module itself
    27  	// cannot access any information about the socket due to limitations
    28  	// with WASI preview 1 networking, and the WASM runtimes do not log the
    29  	// port when you pre-open a socket. So, we probe for a free port here.
    30  	// Given there's an unavoidable race condition, the test is disabled by
    31  	// default.
    32  	if os.Getenv("GOWASIENABLERACYTEST") != "1" {
    33  		t.Skip("skipping WASI test with unavoidable race condition")
    34  	}
    35  	var host string
    36  	port := rand.Intn(10000) + 40000
    37  	for attempts := 0; attempts < 10; attempts++ {
    38  		host = fmt.Sprintf("127.0.0.1:%d", port)
    39  		l, err := net.Listen("tcp", host)
    40  		if err == nil {
    41  			l.Close()
    42  			break
    43  		}
    44  		port++
    45  	}
    46  
    47  	subProcess := exec.Command("go", "run", "./testdata/tcpecho.go")
    48  
    49  	subProcess.Env = append(os.Environ(), "GOOS=wasip1", "GOARCH=wasm")
    50  
    51  	switch os.Getenv("GOWASIRUNTIME") {
    52  	case "wazero":
    53  		subProcess.Env = append(subProcess.Env, "GOWASIRUNTIMEARGS=--listen="+host)
    54  	case "wasmtime", "":
    55  		subProcess.Env = append(subProcess.Env, "GOWASIRUNTIMEARGS=--tcplisten="+host)
    56  	default:
    57  		t.Skip("WASI runtime does not support sockets")
    58  	}
    59  
    60  	var b bytes.Buffer
    61  	subProcess.Stdout = &b
    62  	subProcess.Stderr = &b
    63  
    64  	if err := subProcess.Start(); err != nil {
    65  		t.Log(b.String())
    66  		t.Fatal(err)
    67  	}
    68  	defer subProcess.Process.Kill()
    69  
    70  	var conn net.Conn
    71  	for {
    72  		var err error
    73  		conn, err = net.Dial("tcp", host)
    74  		if err == nil {
    75  			break
    76  		}
    77  		time.Sleep(500 * time.Millisecond)
    78  	}
    79  	defer conn.Close()
    80  
    81  	payload := []byte("foobar")
    82  	if _, err := conn.Write(payload); err != nil {
    83  		t.Fatal(err)
    84  	}
    85  	var buf [256]byte
    86  	n, err := conn.Read(buf[:])
    87  	if err != nil {
    88  		t.Fatal(err)
    89  	}
    90  	if string(buf[:n]) != string(payload) {
    91  		t.Error("unexpected payload")
    92  		t.Logf("expect: %d bytes (%v)", len(payload), payload)
    93  		t.Logf("actual: %d bytes (%v)", n, buf[:n])
    94  	}
    95  }
    96
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