Source file src/net/dnsconfig_unix_test.go

     1  // Copyright 2013 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  //go:build unix
     6  
     7  package net
     8  
     9  import (
    10  	"errors"
    11  	"io/fs"
    12  	"os"
    13  	"reflect"
    14  	"slices"
    15  	"strings"
    16  	"testing"
    17  	"time"
    18  )
    19  
    20  var dnsReadConfigTests = []struct {
    21  	name string
    22  	want *dnsConfig
    23  }{
    24  	{
    25  		name: "testdata/resolv.conf",
    26  		want: &dnsConfig{
    27  			servers:    []string{"8.8.8.8:53", "[2001:4860:4860::8888]:53", "[fe80::1%lo0]:53"},
    28  			search:     []string{"localdomain."},
    29  			ndots:      5,
    30  			timeout:    10 * time.Second,
    31  			attempts:   3,
    32  			rotate:     true,
    33  			unknownOpt: true, // the "options attempts 3" line
    34  		},
    35  	},
    36  	{
    37  		name: "testdata/domain-resolv.conf",
    38  		want: &dnsConfig{
    39  			servers:  []string{"8.8.8.8:53"},
    40  			search:   []string{"localdomain."},
    41  			ndots:    1,
    42  			timeout:  5 * time.Second,
    43  			attempts: 2,
    44  		},
    45  	},
    46  	{
    47  		name: "testdata/search-resolv.conf",
    48  		want: &dnsConfig{
    49  			servers:  []string{"8.8.8.8:53"},
    50  			search:   []string{"test.", "invalid."},
    51  			ndots:    1,
    52  			timeout:  5 * time.Second,
    53  			attempts: 2,
    54  		},
    55  	},
    56  	{
    57  		name: "testdata/search-single-dot-resolv.conf",
    58  		want: &dnsConfig{
    59  			servers:  []string{"8.8.8.8:53"},
    60  			search:   []string{},
    61  			ndots:    1,
    62  			timeout:  5 * time.Second,
    63  			attempts: 2,
    64  		},
    65  	},
    66  	{
    67  		name: "testdata/empty-resolv.conf",
    68  		want: &dnsConfig{
    69  			servers:  defaultNS,
    70  			ndots:    1,
    71  			timeout:  5 * time.Second,
    72  			attempts: 2,
    73  			search:   []string{"domain.local."},
    74  		},
    75  	},
    76  	{
    77  		name: "testdata/invalid-ndots-resolv.conf",
    78  		want: &dnsConfig{
    79  			servers:  defaultNS,
    80  			ndots:    0,
    81  			timeout:  5 * time.Second,
    82  			attempts: 2,
    83  			search:   []string{"domain.local."},
    84  		},
    85  	},
    86  	{
    87  		name: "testdata/large-ndots-resolv.conf",
    88  		want: &dnsConfig{
    89  			servers:  defaultNS,
    90  			ndots:    15,
    91  			timeout:  5 * time.Second,
    92  			attempts: 2,
    93  			search:   []string{"domain.local."},
    94  		},
    95  	},
    96  	{
    97  		name: "testdata/negative-ndots-resolv.conf",
    98  		want: &dnsConfig{
    99  			servers:  defaultNS,
   100  			ndots:    0,
   101  			timeout:  5 * time.Second,
   102  			attempts: 2,
   103  			search:   []string{"domain.local."},
   104  		},
   105  	},
   106  	{
   107  		name: "testdata/openbsd-resolv.conf",
   108  		want: &dnsConfig{
   109  			ndots:    1,
   110  			timeout:  5 * time.Second,
   111  			attempts: 2,
   112  			lookup:   []string{"file", "bind"},
   113  			servers:  []string{"169.254.169.254:53", "10.240.0.1:53"},
   114  			search:   []string{"c.symbolic-datum-552.internal."},
   115  		},
   116  	},
   117  	{
   118  		name: "testdata/single-request-resolv.conf",
   119  		want: &dnsConfig{
   120  			servers:       defaultNS,
   121  			ndots:         1,
   122  			singleRequest: true,
   123  			timeout:       5 * time.Second,
   124  			attempts:      2,
   125  			search:        []string{"domain.local."},
   126  		},
   127  	},
   128  	{
   129  		name: "testdata/single-request-reopen-resolv.conf",
   130  		want: &dnsConfig{
   131  			servers:       defaultNS,
   132  			ndots:         1,
   133  			singleRequest: true,
   134  			timeout:       5 * time.Second,
   135  			attempts:      2,
   136  			search:        []string{"domain.local."},
   137  		},
   138  	},
   139  	{
   140  		name: "testdata/linux-use-vc-resolv.conf",
   141  		want: &dnsConfig{
   142  			servers:  defaultNS,
   143  			ndots:    1,
   144  			useTCP:   true,
   145  			timeout:  5 * time.Second,
   146  			attempts: 2,
   147  			search:   []string{"domain.local."},
   148  		},
   149  	},
   150  	{
   151  		name: "testdata/freebsd-usevc-resolv.conf",
   152  		want: &dnsConfig{
   153  			servers:  defaultNS,
   154  			ndots:    1,
   155  			useTCP:   true,
   156  			timeout:  5 * time.Second,
   157  			attempts: 2,
   158  			search:   []string{"domain.local."},
   159  		},
   160  	},
   161  	{
   162  		name: "testdata/openbsd-tcp-resolv.conf",
   163  		want: &dnsConfig{
   164  			servers:  defaultNS,
   165  			ndots:    1,
   166  			useTCP:   true,
   167  			timeout:  5 * time.Second,
   168  			attempts: 2,
   169  			search:   []string{"domain.local."},
   170  		},
   171  	},
   172  }
   173  
   174  func TestDNSReadConfig(t *testing.T) {
   175  	origGetHostname := getHostname
   176  	defer func() { getHostname = origGetHostname }()
   177  	getHostname = func() (string, error) { return "host.domain.local", nil }
   178  
   179  	for _, tt := range dnsReadConfigTests {
   180  		want := *tt.want
   181  		if len(want.search) == 0 {
   182  			want.search = dnsDefaultSearch()
   183  		}
   184  		conf := dnsReadConfig(tt.name)
   185  		if conf.err != nil {
   186  			t.Fatal(conf.err)
   187  		}
   188  		conf.mtime = time.Time{}
   189  		if !reflect.DeepEqual(conf, &want) {
   190  			t.Errorf("%s:\ngot: %+v\nwant: %+v", tt.name, conf, want)
   191  		}
   192  	}
   193  }
   194  
   195  func TestDNSReadMissingFile(t *testing.T) {
   196  	origGetHostname := getHostname
   197  	defer func() { getHostname = origGetHostname }()
   198  	getHostname = func() (string, error) { return "host.domain.local", nil }
   199  
   200  	conf := dnsReadConfig("a-nonexistent-file")
   201  	if !os.IsNotExist(conf.err) {
   202  		t.Errorf("missing resolv.conf:\ngot: %v\nwant: %v", conf.err, fs.ErrNotExist)
   203  	}
   204  	conf.err = nil
   205  	want := &dnsConfig{
   206  		servers:  defaultNS,
   207  		ndots:    1,
   208  		timeout:  5 * time.Second,
   209  		attempts: 2,
   210  		search:   []string{"domain.local."},
   211  	}
   212  	if !reflect.DeepEqual(conf, want) {
   213  		t.Errorf("missing resolv.conf:\ngot: %+v\nwant: %+v", conf, want)
   214  	}
   215  }
   216  
   217  var dnsDefaultSearchTests = []struct {
   218  	name string
   219  	err  error
   220  	want []string
   221  }{
   222  	{
   223  		name: "host.long.domain.local",
   224  		want: []string{"long.domain.local."},
   225  	},
   226  	{
   227  		name: "host.local",
   228  		want: []string{"local."},
   229  	},
   230  	{
   231  		name: "host",
   232  		want: nil,
   233  	},
   234  	{
   235  		name: "host.domain.local",
   236  		err:  errors.New("errored"),
   237  		want: nil,
   238  	},
   239  	{
   240  		// ensures we don't return []string{""}
   241  		// which causes duplicate lookups
   242  		name: "foo.",
   243  		want: nil,
   244  	},
   245  }
   246  
   247  func TestDNSDefaultSearch(t *testing.T) {
   248  	origGetHostname := getHostname
   249  	defer func() { getHostname = origGetHostname }()
   250  
   251  	for _, tt := range dnsDefaultSearchTests {
   252  		getHostname = func() (string, error) { return tt.name, tt.err }
   253  		got := dnsDefaultSearch()
   254  		if !slices.Equal(got, tt.want) {
   255  			t.Errorf("dnsDefaultSearch with hostname %q and error %+v = %q, wanted %q", tt.name, tt.err, got, tt.want)
   256  		}
   257  	}
   258  }
   259  
   260  func TestDNSNameLength(t *testing.T) {
   261  	origGetHostname := getHostname
   262  	defer func() { getHostname = origGetHostname }()
   263  	getHostname = func() (string, error) { return "host.domain.local", nil }
   264  
   265  	var char63 = ""
   266  	for i := 0; i < 63; i++ {
   267  		char63 += "a"
   268  	}
   269  	longDomain := strings.Repeat(char63+".", 5) + "example"
   270  
   271  	for _, tt := range dnsReadConfigTests {
   272  		conf := dnsReadConfig(tt.name)
   273  		if conf.err != nil {
   274  			t.Fatal(conf.err)
   275  		}
   276  
   277  		suffixList := tt.want.search
   278  		if len(suffixList) == 0 {
   279  			suffixList = dnsDefaultSearch()
   280  		}
   281  
   282  		var shortestSuffix int
   283  		for _, suffix := range suffixList {
   284  			if shortestSuffix == 0 || len(suffix) < shortestSuffix {
   285  				shortestSuffix = len(suffix)
   286  			}
   287  		}
   288  
   289  		// Test a name that will be maximally long when prefixing the shortest
   290  		// suffix (accounting for the intervening dot).
   291  		longName := longDomain[len(longDomain)-254+1+shortestSuffix:]
   292  		if longName[0] == '.' || longName[1] == '.' {
   293  			longName = "aa." + longName[3:]
   294  		}
   295  		for _, fqdn := range conf.nameList(longName) {
   296  			if len(fqdn) > 254 {
   297  				t.Errorf("got %d; want less than or equal to 254", len(fqdn))
   298  			}
   299  		}
   300  
   301  		// Now test a name that's too long for suffixing.
   302  		unsuffixable := "a." + longName[1:]
   303  		unsuffixableResults := conf.nameList(unsuffixable)
   304  		if len(unsuffixableResults) != 1 {
   305  			t.Errorf("suffixed names %v; want []", unsuffixableResults[1:])
   306  		}
   307  
   308  		// Now test a name that's too long for DNS.
   309  		tooLong := "a." + longDomain
   310  		tooLongResults := conf.nameList(tooLong)
   311  		if tooLongResults != nil {
   312  			t.Errorf("suffixed names %v; want nil", tooLongResults)
   313  		}
   314  	}
   315  }
   316  

View as plain text