net: fix inconsistent error values on Dial, Listen partially

This change makes TestDialError, TestListenError work without any
external dependency, enables them by default, and removes unnecessary
-run_error_test flag for fixing #4856.

Also fixes inconsistent error values on Dial, Listen partially as a
first stab.

Updates #4856.

Change-Id: Ie10c151ae06759085f352c7db2ca45107a81914f
Reviewed-on: https://go-review.googlesource.com/8903
Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/net/error_test.go

@@ -0,0 +1,199 @@
+// Copyright 2015 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 net
+
+import (
+	"fmt"
+	"net/internal/socktest"
+	"os"
+	"runtime"
+	"testing"
+)
+
+func isTimeoutError(err error) bool {
+	nerr, ok := err.(Error)
+	return ok && nerr.Timeout()
+}
+
+func isTemporaryError(err error) bool {
+	nerr, ok := err.(Error)
+	return ok && nerr.Temporary()
+}
+
+func (e *OpError) isValid() error {
+	if e.Op == "" {
+		return fmt.Errorf("OpError.Op is empty: %v", e)
+	}
+	if e.Net == "" {
+		return fmt.Errorf("OpError.Net is empty: %v", e)
+	}
+	switch addr := e.Addr.(type) {
+	case *TCPAddr:
+		if addr == nil {
+			return fmt.Errorf("OpError.Addr is empty: %v", e)
+		}
+	case *UDPAddr:
+		if addr == nil {
+			return fmt.Errorf("OpError.Addr is empty: %v", e)
+		}
+	case *IPAddr:
+		if addr == nil {
+			return fmt.Errorf("OpError.Addr is empty: %v", e)
+		}
+	case *IPNet:
+		if addr == nil {
+			return fmt.Errorf("OpError.Addr is empty: %v", e)
+		}
+	case *UnixAddr:
+		if addr == nil {
+			return fmt.Errorf("OpError.Addr is empty: %v", e)
+		}
+	case *pipeAddr:
+		if addr == nil {
+			return fmt.Errorf("OpError.Addr is empty: %v", e)
+		}
+	}
+	if e.Err == nil {
+		return fmt.Errorf("OpError.Err is empty: %v", e)
+	}
+	return nil
+}
+
+// parseDialError parses nestedErr and reports whether it is a valid
+// error value from Dial, Listen functions.
+// It returns nil when nestedErr is valid.
+func parseDialError(nestedErr error) error {
+	if nestedErr == nil {
+		return nil
+	}
+
+	switch err := nestedErr.(type) {
+	case *OpError:
+		if err := err.isValid(); err != nil {
+			return err
+		}
+		nestedErr = err.Err
+		goto second
+	}
+	return fmt.Errorf("unexpected type on 1st nested level: %T", nestedErr)
+
+second:
+	if isPlatformError(nestedErr) {
+		return nil
+	}
+	switch err := nestedErr.(type) {
+	case *AddrError, *DNSError, InvalidAddrError, *ParseError, UnknownNetworkError, *timeoutError:
+		return nil
+	case *DNSConfigError:
+		nestedErr = err.Err
+		goto third
+	case *os.SyscallError:
+		nestedErr = err.Err
+		goto third
+	}
+	switch nestedErr {
+	case errClosing, errMissingAddress:
+		return nil
+	}
+	return fmt.Errorf("unexpected type on 2nd nested level: %T", nestedErr)
+
+third:
+	if isPlatformError(nestedErr) {
+		return nil
+	}
+	return fmt.Errorf("unexpected type on 3rd nested level: %T", nestedErr)
+}
+
+var dialErrorTests = []struct {
+	network, address string
+}{
+	{"foo", ""},
+	{"bar", "baz"},
+	{"datakit", "mh/astro/r70"},
+	{"tcp", ""},
+	{"tcp", "127.0.0.1:☺"},
+	{"tcp", "no-such-name:80"},
+	{"tcp", "mh/astro/r70:http"},
+
+	{"tcp", "127.0.0.1:0"},
+	{"udp", "127.0.0.1:0"},
+	{"ip:icmp", "127.0.0.1"},
+
+	{"unix", "/path/to/somewhere"},
+	{"unixgram", "/path/to/somewhere"},
+	{"unixpacket", "/path/to/somewhere"},
+}
+
+func TestDialError(t *testing.T) {
+	switch runtime.GOOS {
+	case "plan9":
+		t.Skipf("%s does not have full support of socktest", runtime.GOOS)
+	}
+
+	origTestHookLookupIP := testHookLookupIP
+	defer func() { testHookLookupIP = origTestHookLookupIP }()
+	testHookLookupIP = func(fn func(string) ([]IPAddr, error), host string) ([]IPAddr, error) {
+		return nil, &DNSError{Err: "dial error test", Name: "name", Server: "server", IsTimeout: true}
+	}
+	sw.Set(socktest.FilterConnect, func(so *socktest.Status) (socktest.AfterFilter, error) {
+		return nil, errOpNotSupported
+	})
+	defer sw.Set(socktest.FilterConnect, nil)
+
+	d := Dialer{Timeout: someTimeout}
+	for i, tt := range dialErrorTests {
+		c, err := d.Dial(tt.network, tt.address)
+		if err == nil {
+			t.Errorf("#%d: should fail; %s:%s->%s", i, tt.network, c.LocalAddr(), c.RemoteAddr())
+			c.Close()
+			continue
+		}
+		if err = parseDialError(err); err != nil {
+			t.Errorf("#%d: %v", i, err)
+			continue
+		}
+	}
+}
+
+var listenErrorTests = []struct {
+	network, address string
+}{
+	{"foo", ""},
+	{"bar", "baz"},
+	{"datakit", "mh/astro/r70"},
+	{"tcp", "127.0.0.1:☺"},
+	{"tcp", "no-such-name:80"},
+	{"tcp", "mh/astro/r70:http"},
+}
+
+func TestListenError(t *testing.T) {
+	switch runtime.GOOS {
+	case "plan9":
+		t.Skipf("%s does not have full support of socktest", runtime.GOOS)
+	}
+
+	origTestHookLookupIP := testHookLookupIP
+	defer func() { testHookLookupIP = origTestHookLookupIP }()
+	testHookLookupIP = func(fn func(string) ([]IPAddr, error), host string) ([]IPAddr, error) {
+		return nil, &DNSError{Err: "listen error test", Name: "name", Server: "server", IsTimeout: true}
+	}
+	sw.Set(socktest.FilterListen, func(so *socktest.Status) (socktest.AfterFilter, error) {
+		return nil, errOpNotSupported
+	})
+	defer sw.Set(socktest.FilterListen, nil)
+
+	for i, tt := range listenErrorTests {
+		ln, err := Listen(tt.network, tt.address)
+		if err == nil {
+			t.Errorf("#%d: should fail; %s:%s->", i, tt.network, ln.Addr())
+			ln.Close()
+			continue
+		}
+		if err = parseDialError(err); err != nil {
+			t.Errorf("#%d: %v", i, err)
+			continue
+		}
+	}
+}