main_conf_test.go

     1  // Copyright 2015 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 net
     6  
     7  import (
     8  	"context"
     9  	"runtime"
    10  	"testing"
    11  )
    12  
    13  func allResolvers(t *testing.T, f func(t *testing.T)) {
    14  	t.Run("default resolver", f)
    15  	t.Run("forced go resolver", func(t *testing.T) {
    16  		// On plan9 the forceGoDNS might not force the go resolver, currently
    17  		// it is only forced when the Resolver.Dial field is populated.
    18  		// See conf.go mustUseGoResolver.
    19  		defer forceGoDNS()()
    20  		f(t)
    21  	})
    22  	t.Run("forced cgo resolver", func(t *testing.T) {
    23  		defer forceCgoDNS()()
    24  		f(t)
    25  	})
    26  }
    27  
    28  // forceGoDNS forces the resolver configuration to use the pure Go resolver
    29  // and returns a fixup function to restore the old settings.
    30  func forceGoDNS() func() {
    31  	c := systemConf()
    32  	oldGo := c.netGo
    33  	oldCgo := c.netCgo
    34  	fixup := func() {
    35  		c.netGo = oldGo
    36  		c.netCgo = oldCgo
    37  	}
    38  	c.netGo = true
    39  	c.netCgo = false
    40  	return fixup
    41  }
    42  
    43  // forceCgoDNS forces the resolver configuration to use the cgo resolver
    44  // and returns a fixup function to restore the old settings.
    45  func forceCgoDNS() func() {
    46  	c := systemConf()
    47  	oldGo := c.netGo
    48  	oldCgo := c.netCgo
    49  	fixup := func() {
    50  		c.netGo = oldGo
    51  		c.netCgo = oldCgo
    52  	}
    53  	c.netGo = false
    54  	c.netCgo = true
    55  	return fixup
    56  }
    57  
    58  func TestForceCgoDNS(t *testing.T) {
    59  	if !cgoAvailable {
    60  		t.Skip("cgo resolver not available")
    61  	}
    62  	defer forceCgoDNS()()
    63  	order, _ := systemConf().hostLookupOrder(nil, "go.dev")
    64  	if order != hostLookupCgo {
    65  		t.Fatalf("hostLookupOrder returned: %v, want cgo", order)
    66  	}
    67  	order, _ = systemConf().addrLookupOrder(nil, "192.0.2.1")
    68  	if order != hostLookupCgo {
    69  		t.Fatalf("addrLookupOrder returned: %v, want cgo", order)
    70  	}
    71  	if systemConf().mustUseGoResolver(nil) {
    72  		t.Fatal("mustUseGoResolver = true, want false")
    73  	}
    74  }
    75  
    76  func TestForceGoDNS(t *testing.T) {
    77  	var resolver *Resolver
    78  	if runtime.GOOS == "plan9" {
    79  		resolver = &Resolver{
    80  			Dial: func(_ context.Context, _, _ string) (Conn, error) {
    81  				panic("unreachable")
    82  			},
    83  		}
    84  	}
    85  	defer forceGoDNS()()
    86  	order, _ := systemConf().hostLookupOrder(resolver, "go.dev")
    87  	if order == hostLookupCgo {
    88  		t.Fatalf("hostLookupOrder returned: %v, want go resolver order", order)
    89  	}
    90  	order, _ = systemConf().addrLookupOrder(resolver, "192.0.2.1")
    91  	if order == hostLookupCgo {
    92  		t.Fatalf("addrLookupOrder returned: %v, want go resolver order", order)
    93  	}
    94  	if !systemConf().mustUseGoResolver(resolver) {
    95  		t.Fatal("mustUseGoResolver = false, want true")
    96  	}
    97  }
    98
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