conntest.go

     1  // Copyright 2016 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 nettest
     6  
     7  import (
     8  	"bytes"
     9  	"encoding/binary"
    10  	"io"
    11  	"io/ioutil"
    12  	"math/rand"
    13  	"net"
    14  	"runtime"
    15  	"sync"
    16  	"testing"
    17  	"time"
    18  )
    19  
    20  // MakePipe creates a connection between two endpoints and returns the pair
    21  // as c1 and c2, such that anything written to c1 is read by c2 and vice-versa.
    22  // The stop function closes all resources, including c1, c2, and the underlying
    23  // net.Listener (if there is one), and should not be nil.
    24  type MakePipe func() (c1, c2 net.Conn, stop func(), err error)
    25  
    26  // TestConn tests that a net.Conn implementation properly satisfies the interface.
    27  // The tests should not produce any false positives, but may experience
    28  // false negatives. Thus, some issues may only be detected when the test is
    29  // run multiple times. For maximal effectiveness, run the tests under the
    30  // race detector.
    31  func TestConn(t *testing.T, mp MakePipe) {
    32  	t.Run("BasicIO", func(t *testing.T) { timeoutWrapper(t, mp, testBasicIO) })
    33  	t.Run("PingPong", func(t *testing.T) { timeoutWrapper(t, mp, testPingPong) })
    34  	t.Run("RacyRead", func(t *testing.T) { timeoutWrapper(t, mp, testRacyRead) })
    35  	t.Run("RacyWrite", func(t *testing.T) { timeoutWrapper(t, mp, testRacyWrite) })
    36  	t.Run("ReadTimeout", func(t *testing.T) { timeoutWrapper(t, mp, testReadTimeout) })
    37  	t.Run("WriteTimeout", func(t *testing.T) { timeoutWrapper(t, mp, testWriteTimeout) })
    38  	t.Run("PastTimeout", func(t *testing.T) { timeoutWrapper(t, mp, testPastTimeout) })
    39  	t.Run("PresentTimeout", func(t *testing.T) { timeoutWrapper(t, mp, testPresentTimeout) })
    40  	t.Run("FutureTimeout", func(t *testing.T) { timeoutWrapper(t, mp, testFutureTimeout) })
    41  	t.Run("CloseTimeout", func(t *testing.T) { timeoutWrapper(t, mp, testCloseTimeout) })
    42  	t.Run("ConcurrentMethods", func(t *testing.T) { timeoutWrapper(t, mp, testConcurrentMethods) })
    43  }
    44  
    45  type connTester func(t *testing.T, c1, c2 net.Conn)
    46  
    47  func timeoutWrapper(t *testing.T, mp MakePipe, f connTester) {
    48  	t.Helper()
    49  	c1, c2, stop, err := mp()
    50  	if err != nil {
    51  		t.Fatalf("unable to make pipe: %v", err)
    52  	}
    53  	var once sync.Once
    54  	defer once.Do(func() { stop() })
    55  	timer := time.AfterFunc(time.Minute, func() {
    56  		once.Do(func() {
    57  			t.Error("test timed out; terminating pipe")
    58  			stop()
    59  		})
    60  	})
    61  	defer timer.Stop()
    62  	f(t, c1, c2)
    63  }
    64  
    65  // testBasicIO tests that the data sent on c1 is properly received on c2.
    66  func testBasicIO(t *testing.T, c1, c2 net.Conn) {
    67  	want := make([]byte, 1<<20)
    68  	rand.New(rand.NewSource(0)).Read(want)
    69  
    70  	dataCh := make(chan []byte)
    71  	go func() {
    72  		rd := bytes.NewReader(want)
    73  		if err := chunkedCopy(c1, rd); err != nil {
    74  			t.Errorf("unexpected c1.Write error: %v", err)
    75  		}
    76  		if err := c1.Close(); err != nil {
    77  			t.Errorf("unexpected c1.Close error: %v", err)
    78  		}
    79  	}()
    80  
    81  	go func() {
    82  		wr := new(bytes.Buffer)
    83  		if err := chunkedCopy(wr, c2); err != nil {
    84  			t.Errorf("unexpected c2.Read error: %v", err)
    85  		}
    86  		if err := c2.Close(); err != nil {
    87  			t.Errorf("unexpected c2.Close error: %v", err)
    88  		}
    89  		dataCh <- wr.Bytes()
    90  	}()
    91  
    92  	if got := <-dataCh; !bytes.Equal(got, want) {
    93  		t.Error("transmitted data differs")
    94  	}
    95  }
    96  
    97  // testPingPong tests that the two endpoints can synchronously send data to
    98  // each other in a typical request-response pattern.
    99  func testPingPong(t *testing.T, c1, c2 net.Conn) {
   100  	var wg sync.WaitGroup
   101  	defer wg.Wait()
   102  
   103  	pingPonger := func(c net.Conn) {
   104  		defer wg.Done()
   105  		buf := make([]byte, 8)
   106  		var prev uint64
   107  		for {
   108  			if _, err := io.ReadFull(c, buf); err != nil {
   109  				if err == io.EOF {
   110  					break
   111  				}
   112  				t.Errorf("unexpected Read error: %v", err)
   113  			}
   114  
   115  			v := binary.LittleEndian.Uint64(buf)
   116  			binary.LittleEndian.PutUint64(buf, v+1)
   117  			if prev != 0 && prev+2 != v {
   118  				t.Errorf("mismatching value: got %d, want %d", v, prev+2)
   119  			}
   120  			prev = v
   121  			if v == 1000 {
   122  				break
   123  			}
   124  
   125  			if _, err := c.Write(buf); err != nil {
   126  				t.Errorf("unexpected Write error: %v", err)
   127  				break
   128  			}
   129  		}
   130  		if err := c.Close(); err != nil {
   131  			t.Errorf("unexpected Close error: %v", err)
   132  		}
   133  	}
   134  
   135  	wg.Add(2)
   136  	go pingPonger(c1)
   137  	go pingPonger(c2)
   138  
   139  	// Start off the chain reaction.
   140  	if _, err := c1.Write(make([]byte, 8)); err != nil {
   141  		t.Errorf("unexpected c1.Write error: %v", err)
   142  	}
   143  }
   144  
   145  // testRacyRead tests that it is safe to mutate the input Read buffer
   146  // immediately after cancelation has occurred.
   147  func testRacyRead(t *testing.T, c1, c2 net.Conn) {
   148  	go chunkedCopy(c2, rand.New(rand.NewSource(0)))
   149  
   150  	var wg sync.WaitGroup
   151  	defer wg.Wait()
   152  
   153  	c1.SetReadDeadline(time.Now().Add(time.Millisecond))
   154  	for i := 0; i < 10; i++ {
   155  		wg.Add(1)
   156  		go func() {
   157  			defer wg.Done()
   158  
   159  			b1 := make([]byte, 1024)
   160  			b2 := make([]byte, 1024)
   161  			for j := 0; j < 100; j++ {
   162  				_, err := c1.Read(b1)
   163  				copy(b1, b2) // Mutate b1 to trigger potential race
   164  				if err != nil {
   165  					checkForTimeoutError(t, err)
   166  					c1.SetReadDeadline(time.Now().Add(time.Millisecond))
   167  				}
   168  			}
   169  		}()
   170  	}
   171  }
   172  
   173  // testRacyWrite tests that it is safe to mutate the input Write buffer
   174  // immediately after cancelation has occurred.
   175  func testRacyWrite(t *testing.T, c1, c2 net.Conn) {
   176  	go chunkedCopy(ioutil.Discard, c2)
   177  
   178  	var wg sync.WaitGroup
   179  	defer wg.Wait()
   180  
   181  	c1.SetWriteDeadline(time.Now().Add(time.Millisecond))
   182  	for i := 0; i < 10; i++ {
   183  		wg.Add(1)
   184  		go func() {
   185  			defer wg.Done()
   186  
   187  			b1 := make([]byte, 1024)
   188  			b2 := make([]byte, 1024)
   189  			for j := 0; j < 100; j++ {
   190  				_, err := c1.Write(b1)
   191  				copy(b1, b2) // Mutate b1 to trigger potential race
   192  				if err != nil {
   193  					checkForTimeoutError(t, err)
   194  					c1.SetWriteDeadline(time.Now().Add(time.Millisecond))
   195  				}
   196  			}
   197  		}()
   198  	}
   199  }
   200  
   201  // testReadTimeout tests that Read timeouts do not affect Write.
   202  func testReadTimeout(t *testing.T, c1, c2 net.Conn) {
   203  	go chunkedCopy(ioutil.Discard, c2)
   204  
   205  	c1.SetReadDeadline(aLongTimeAgo)
   206  	_, err := c1.Read(make([]byte, 1024))
   207  	checkForTimeoutError(t, err)
   208  	if _, err := c1.Write(make([]byte, 1024)); err != nil {
   209  		t.Errorf("unexpected Write error: %v", err)
   210  	}
   211  }
   212  
   213  // testWriteTimeout tests that Write timeouts do not affect Read.
   214  func testWriteTimeout(t *testing.T, c1, c2 net.Conn) {
   215  	go chunkedCopy(c2, rand.New(rand.NewSource(0)))
   216  
   217  	c1.SetWriteDeadline(aLongTimeAgo)
   218  	_, err := c1.Write(make([]byte, 1024))
   219  	checkForTimeoutError(t, err)
   220  	if _, err := c1.Read(make([]byte, 1024)); err != nil {
   221  		t.Errorf("unexpected Read error: %v", err)
   222  	}
   223  }
   224  
   225  // testPastTimeout tests that a deadline set in the past immediately times out
   226  // Read and Write requests.
   227  func testPastTimeout(t *testing.T, c1, c2 net.Conn) {
   228  	go chunkedCopy(c2, c2)
   229  
   230  	testRoundtrip(t, c1)
   231  
   232  	c1.SetDeadline(aLongTimeAgo)
   233  	n, err := c1.Write(make([]byte, 1024))
   234  	if n != 0 {
   235  		t.Errorf("unexpected Write count: got %d, want 0", n)
   236  	}
   237  	checkForTimeoutError(t, err)
   238  	n, err = c1.Read(make([]byte, 1024))
   239  	if n != 0 {
   240  		t.Errorf("unexpected Read count: got %d, want 0", n)
   241  	}
   242  	checkForTimeoutError(t, err)
   243  
   244  	testRoundtrip(t, c1)
   245  }
   246  
   247  // testPresentTimeout tests that a past deadline set while there are pending
   248  // Read and Write operations immediately times out those operations.
   249  func testPresentTimeout(t *testing.T, c1, c2 net.Conn) {
   250  	var wg sync.WaitGroup
   251  	defer wg.Wait()
   252  	wg.Add(3)
   253  
   254  	deadlineSet := make(chan bool, 1)
   255  	go func() {
   256  		defer wg.Done()
   257  		time.Sleep(100 * time.Millisecond)
   258  		deadlineSet <- true
   259  		c1.SetReadDeadline(aLongTimeAgo)
   260  		c1.SetWriteDeadline(aLongTimeAgo)
   261  	}()
   262  	go func() {
   263  		defer wg.Done()
   264  		n, err := c1.Read(make([]byte, 1024))
   265  		if n != 0 {
   266  			t.Errorf("unexpected Read count: got %d, want 0", n)
   267  		}
   268  		checkForTimeoutError(t, err)
   269  		if len(deadlineSet) == 0 {
   270  			t.Error("Read timed out before deadline is set")
   271  		}
   272  	}()
   273  	go func() {
   274  		defer wg.Done()
   275  		var err error
   276  		for err == nil {
   277  			_, err = c1.Write(make([]byte, 1024))
   278  		}
   279  		checkForTimeoutError(t, err)
   280  		if len(deadlineSet) == 0 {
   281  			t.Error("Write timed out before deadline is set")
   282  		}
   283  	}()
   284  }
   285  
   286  // testFutureTimeout tests that a future deadline will eventually time out
   287  // Read and Write operations.
   288  func testFutureTimeout(t *testing.T, c1, c2 net.Conn) {
   289  	var wg sync.WaitGroup
   290  	wg.Add(2)
   291  
   292  	c1.SetDeadline(time.Now().Add(100 * time.Millisecond))
   293  	go func() {
   294  		defer wg.Done()
   295  		_, err := c1.Read(make([]byte, 1024))
   296  		checkForTimeoutError(t, err)
   297  	}()
   298  	go func() {
   299  		defer wg.Done()
   300  		var err error
   301  		for err == nil {
   302  			_, err = c1.Write(make([]byte, 1024))
   303  		}
   304  		checkForTimeoutError(t, err)
   305  	}()
   306  	wg.Wait()
   307  
   308  	go chunkedCopy(c2, c2)
   309  	resyncConn(t, c1)
   310  	testRoundtrip(t, c1)
   311  }
   312  
   313  // testCloseTimeout tests that calling Close immediately times out pending
   314  // Read and Write operations.
   315  func testCloseTimeout(t *testing.T, c1, c2 net.Conn) {
   316  	go chunkedCopy(c2, c2)
   317  
   318  	var wg sync.WaitGroup
   319  	defer wg.Wait()
   320  	wg.Add(3)
   321  
   322  	// Test for cancelation upon connection closure.
   323  	c1.SetDeadline(neverTimeout)
   324  	go func() {
   325  		defer wg.Done()
   326  		time.Sleep(100 * time.Millisecond)
   327  		c1.Close()
   328  	}()
   329  	go func() {
   330  		defer wg.Done()
   331  		var err error
   332  		buf := make([]byte, 1024)
   333  		for err == nil {
   334  			_, err = c1.Read(buf)
   335  		}
   336  	}()
   337  	go func() {
   338  		defer wg.Done()
   339  		var err error
   340  		buf := make([]byte, 1024)
   341  		for err == nil {
   342  			_, err = c1.Write(buf)
   343  		}
   344  	}()
   345  }
   346  
   347  // testConcurrentMethods tests that the methods of net.Conn can safely
   348  // be called concurrently.
   349  func testConcurrentMethods(t *testing.T, c1, c2 net.Conn) {
   350  	if runtime.GOOS == "plan9" {
   351  		t.Skip("skipping on plan9; see https://golang.org/issue/20489")
   352  	}
   353  	go chunkedCopy(c2, c2)
   354  
   355  	// The results of the calls may be nonsensical, but this should
   356  	// not trigger a race detector warning.
   357  	var wg sync.WaitGroup
   358  	for i := 0; i < 100; i++ {
   359  		wg.Add(7)
   360  		go func() {
   361  			defer wg.Done()
   362  			c1.Read(make([]byte, 1024))
   363  		}()
   364  		go func() {
   365  			defer wg.Done()
   366  			c1.Write(make([]byte, 1024))
   367  		}()
   368  		go func() {
   369  			defer wg.Done()
   370  			c1.SetDeadline(time.Now().Add(10 * time.Millisecond))
   371  		}()
   372  		go func() {
   373  			defer wg.Done()
   374  			c1.SetReadDeadline(aLongTimeAgo)
   375  		}()
   376  		go func() {
   377  			defer wg.Done()
   378  			c1.SetWriteDeadline(aLongTimeAgo)
   379  		}()
   380  		go func() {
   381  			defer wg.Done()
   382  			c1.LocalAddr()
   383  		}()
   384  		go func() {
   385  			defer wg.Done()
   386  			c1.RemoteAddr()
   387  		}()
   388  	}
   389  	wg.Wait() // At worst, the deadline is set 10ms into the future
   390  
   391  	resyncConn(t, c1)
   392  	testRoundtrip(t, c1)
   393  }
   394  
   395  // checkForTimeoutError checks that the error satisfies the Error interface
   396  // and that Timeout returns true.
   397  func checkForTimeoutError(t *testing.T, err error) {
   398  	t.Helper()
   399  	if nerr, ok := err.(net.Error); ok {
   400  		if !nerr.Timeout() {
   401  			if runtime.GOOS == "windows" && runtime.GOARCH == "arm64" && t.Name() == "TestTestConn/TCP/RacyRead" {
   402  				t.Logf("ignoring known failure mode on windows/arm64; see https://go.dev/issue/52893")
   403  			} else {
   404  				t.Errorf("got error: %v, want err.Timeout() = true", nerr)
   405  			}
   406  		}
   407  	} else {
   408  		t.Errorf("got %T: %v, want net.Error", err, err)
   409  	}
   410  }
   411  
   412  // testRoundtrip writes something into c and reads it back.
   413  // It assumes that everything written into c is echoed back to itself.
   414  func testRoundtrip(t *testing.T, c net.Conn) {
   415  	t.Helper()
   416  	if err := c.SetDeadline(neverTimeout); err != nil {
   417  		t.Errorf("roundtrip SetDeadline error: %v", err)
   418  	}
   419  
   420  	const s = "Hello, world!"
   421  	buf := []byte(s)
   422  	if _, err := c.Write(buf); err != nil {
   423  		t.Errorf("roundtrip Write error: %v", err)
   424  	}
   425  	if _, err := io.ReadFull(c, buf); err != nil {
   426  		t.Errorf("roundtrip Read error: %v", err)
   427  	}
   428  	if string(buf) != s {
   429  		t.Errorf("roundtrip data mismatch: got %q, want %q", buf, s)
   430  	}
   431  }
   432  
   433  // resyncConn resynchronizes the connection into a sane state.
   434  // It assumes that everything written into c is echoed back to itself.
   435  // It assumes that 0xff is not currently on the wire or in the read buffer.
   436  func resyncConn(t *testing.T, c net.Conn) {
   437  	t.Helper()
   438  	c.SetDeadline(neverTimeout)
   439  	errCh := make(chan error)
   440  	go func() {
   441  		_, err := c.Write([]byte{0xff})
   442  		errCh <- err
   443  	}()
   444  	buf := make([]byte, 1024)
   445  	for {
   446  		n, err := c.Read(buf)
   447  		if n > 0 && bytes.IndexByte(buf[:n], 0xff) == n-1 {
   448  			break
   449  		}
   450  		if err != nil {
   451  			t.Errorf("unexpected Read error: %v", err)
   452  			break
   453  		}
   454  	}
   455  	if err := <-errCh; err != nil {
   456  		t.Errorf("unexpected Write error: %v", err)
   457  	}
   458  }
   459  
   460  // chunkedCopy copies from r to w in fixed-width chunks to avoid
   461  // causing a Write that exceeds the maximum packet size for packet-based
   462  // connections like "unixpacket".
   463  // We assume that the maximum packet size is at least 1024.
   464  func chunkedCopy(w io.Writer, r io.Reader) error {
   465  	b := make([]byte, 1024)
   466  	_, err := io.CopyBuffer(struct{ io.Writer }{w}, struct{ io.Reader }{r}, b)
   467  	return err
   468  }
   469
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