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Fix/resolv parser (#1520)

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fix an issue In case if the original resolv.conf file is empty, then it can cause a nil pointer
This commit is contained in:
Zoltan Papp
2024-02-02 17:54:33 +01:00
committed by GitHub
parent f89332fcd2
commit a2f2a6e21a
4 changed files with 124 additions and 46 deletions
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83
client/internal/dns/file_parser_linux_test.go
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@ -3,8 +3,8 @@
package dns
import (
"fmt"
"os"
"path/filepath"
"testing"
)
@ -75,40 +75,13 @@ options debug
expectedNS: []string{"192.168.2.1", "100.81.99.197"},
expectedOther: []string{"options debug"},
},
{
input: `# This is /run/systemd/resolve/resolv.conf managed by man:systemd-resolved(8).
# Do not edit.
#
# This file might be symlinked as /etc/resolv.conf. If you're looking at
# /etc/resolv.conf and seeing this text, you have followed the symlink.
#
# This is a dynamic resolv.conf file for connecting local clients directly to
# all known uplink DNS servers. This file lists all configured search domains.
#
# Third party programs should typically not access this file directly, but only
# through the symlink at /etc/resolv.conf. To manage man:resolv.conf(5) in a
# different way, replace this symlink by a static file or a different symlink.
#
# See man:systemd-resolved.service(8) for details about the supported modes of
# operation for /etc/resolv.conf.
nameserver 192.168.2.1
nameserver 100.81.99.197
search netbird.cloud
options debug
options edns0 trust-ad
`,
expectedSearch: []string{"netbird.cloud"},
expectedNS: []string{"192.168.2.1", "100.81.99.197"},
expectedOther: []string{"options debug", "options edns0 trust-ad"},
},
}
for _, testCase := range testCases {
testCase := testCase
t.Run("test", func(t *testing.T) {
t.Parallel()
tmpResolvConf := fmt.Sprintf("%s/%s", t.TempDir(), "resolv.conf")
tmpResolvConf := filepath.Join(t.TempDir(), "resolv.conf")
err := os.WriteFile(tmpResolvConf, []byte(testCase.input), 0644)
if err != nil {
t.Fatal(err)
@ -147,3 +120,55 @@ func compareLists(search []string, search2 []string) bool {
}
return true
}
func Test_emptyFile(t *testing.T) {
cfg, err := parseResolvConfFile("/tmp/nothing")
if err == nil {
t.Errorf("expected error, got nil")
}
if len(cfg.others) != 0 || len(cfg.searchDomains) != 0 || len(cfg.nameServers) != 0 {
t.Errorf("expected empty config, got %v", cfg)
}
}
func Test_symlink(t *testing.T) {
input := `# This is /run/systemd/resolve/resolv.conf managed by man:systemd-resolved(8).
# Do not edit.
#
# This file might be symlinked as /etc/resolv.conf. If you're looking at
# /etc/resolv.conf and seeing this text, you have followed the symlink.
#
# This is a dynamic resolv.conf file for connecting local clients directly to
# all known uplink DNS servers. This file lists all configured search domains.
#
# Third party programs should typically not access this file directly, but only
# through the symlink at /etc/resolv.conf. To manage man:resolv.conf(5) in a
# different way, replace this symlink by a static file or a different symlink.
#
# See man:systemd-resolved.service(8) for details about the supported modes of
# operation for /etc/resolv.conf.
nameserver 192.168.0.1
`
tmpResolvConf := filepath.Join(t.TempDir(), "resolv.conf")
err := os.WriteFile(tmpResolvConf, []byte(input), 0644)
if err != nil {
t.Fatal(err)
}
tmpLink := filepath.Join(t.TempDir(), "symlink")
err = os.Symlink(tmpResolvConf, tmpLink)
if err != nil {
t.Fatal(err)
}
cfg, err := parseResolvConfFile(tmpLink)
if err != nil {
t.Fatal(err)
}
if len(cfg.nameServers) != 1 {
t.Errorf("unexpected resolv.conf content: %v", cfg)
}
}