Change-Id: I2120893ca802d12f1bd0407d49077d3672627d33 Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>main
Brad Fitzpatrick
4 years ago
committed by
Brad Fitzpatrick
parent
1dc4151f8b
commit
c988bd6ed1
@ -0,0 +1,120 @@ |
||||
// Copyright (c) 2022 Tailscale Inc & 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 resolvconffile parses & serializes /etc/resolv.conf-style files.
|
||||
//
|
||||
// It's a leaf package so both net/dns and net/dns/resolver can depend
|
||||
// on it and we can unify a handful of implementations.
|
||||
//
|
||||
// The package is verbosely named to disambiguate it from resolvconf
|
||||
// the daemon, which Tailscale also supports.
|
||||
package resolvconffile |
||||
|
||||
import ( |
||||
"bufio" |
||||
"bytes" |
||||
"fmt" |
||||
"io" |
||||
"os" |
||||
"strings" |
||||
|
||||
"inet.af/netaddr" |
||||
"tailscale.com/util/dnsname" |
||||
) |
||||
|
||||
// Path is the canonical location of resolv.conf.
|
||||
const Path = "/etc/resolv.conf" |
||||
|
||||
// Config represents a resolv.conf(5) file.
|
||||
type Config struct { |
||||
// Nameservers are the IP addresses of the nameservers to use.
|
||||
Nameservers []netaddr.IP |
||||
|
||||
// SearchDomains are the domain suffixes to use when expanding
|
||||
// single-label name queries. SearchDomains is additive to
|
||||
// whatever non-Tailscale search domains the OS has.
|
||||
SearchDomains []dnsname.FQDN |
||||
} |
||||
|
||||
// Write writes c to w. It does so in one Write call.
|
||||
func (c *Config) Write(w io.Writer) error { |
||||
buf := new(bytes.Buffer) |
||||
io.WriteString(buf, "# resolv.conf(5) file generated by tailscale\n") |
||||
io.WriteString(buf, "# DO NOT EDIT THIS FILE BY HAND -- CHANGES WILL BE OVERWRITTEN\n\n") |
||||
for _, ns := range c.Nameservers { |
||||
io.WriteString(buf, "nameserver ") |
||||
io.WriteString(buf, ns.String()) |
||||
io.WriteString(buf, "\n") |
||||
} |
||||
if len(c.SearchDomains) > 0 { |
||||
io.WriteString(buf, "search") |
||||
for _, domain := range c.SearchDomains { |
||||
io.WriteString(buf, " ") |
||||
io.WriteString(buf, domain.WithoutTrailingDot()) |
||||
} |
||||
io.WriteString(buf, "\n") |
||||
} |
||||
_, err := w.Write(buf.Bytes()) |
||||
return err |
||||
} |
||||
|
||||
// Parse parses a resolv.conf file from r.
|
||||
func Parse(r io.Reader) (*Config, error) { |
||||
config := new(Config) |
||||
scanner := bufio.NewScanner(r) |
||||
for scanner.Scan() { |
||||
line := scanner.Text() |
||||
i := strings.IndexByte(line, '#') |
||||
if i >= 0 { |
||||
line = line[:i] |
||||
} |
||||
line = strings.TrimSpace(line) |
||||
|
||||
if strings.HasPrefix(line, "nameserver") { |
||||
s := strings.TrimPrefix(line, "nameserver") |
||||
nameserver := strings.TrimSpace(s) |
||||
if len(nameserver) == len(s) { |
||||
return nil, fmt.Errorf("missing space after \"nameserver\" in %q", line) |
||||
} |
||||
ip, err := netaddr.ParseIP(nameserver) |
||||
if err != nil { |
||||
return nil, err |
||||
} |
||||
config.Nameservers = append(config.Nameservers, ip) |
||||
continue |
||||
} |
||||
|
||||
if strings.HasPrefix(line, "search") { |
||||
s := strings.TrimPrefix(line, "search") |
||||
domain := strings.TrimSpace(s) |
||||
if len(domain) == len(s) { |
||||
// No leading space?!
|
||||
return nil, fmt.Errorf("missing space after \"domain\" in %q", line) |
||||
} |
||||
fqdn, err := dnsname.ToFQDN(domain) |
||||
if err != nil { |
||||
return nil, fmt.Errorf("parsing search domains %q: %w", line, err) |
||||
} |
||||
config.SearchDomains = append(config.SearchDomains, fqdn) |
||||
continue |
||||
} |
||||
} |
||||
return config, nil |
||||
} |
||||
|
||||
// ParseFile parses the named resolv.conf file.
|
||||
func ParseFile(name string) (*Config, error) { |
||||
fi, err := os.Stat(name) |
||||
if err != nil { |
||||
return nil, err |
||||
} |
||||
if n := fi.Size(); n > 10<<10 { |
||||
return nil, fmt.Errorf("unexpectedly large %q file: %d bytes", name, n) |
||||
} |
||||
all, err := os.ReadFile(name) |
||||
if err != nil { |
||||
return nil, err |
||||
} |
||||
return Parse(bytes.NewReader(all)) |
||||
} |
||||
@ -0,0 +1,79 @@ |
||||
// Copyright (c) 2022 Tailscale Inc & 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 resolvconffile |
||||
|
||||
import ( |
||||
"reflect" |
||||
"strings" |
||||
"testing" |
||||
|
||||
"inet.af/netaddr" |
||||
"tailscale.com/util/dnsname" |
||||
) |
||||
|
||||
func TestParse(t *testing.T) { |
||||
tests := []struct { |
||||
in string |
||||
want *Config |
||||
wantErr bool |
||||
}{ |
||||
{in: `nameserver 192.168.0.100`, |
||||
want: &Config{ |
||||
Nameservers: []netaddr.IP{ |
||||
netaddr.MustParseIP("192.168.0.100"), |
||||
}, |
||||
}, |
||||
}, |
||||
{in: `nameserver 192.168.0.100 # comment`, |
||||
want: &Config{ |
||||
Nameservers: []netaddr.IP{ |
||||
netaddr.MustParseIP("192.168.0.100"), |
||||
}, |
||||
}, |
||||
}, |
||||
{in: `nameserver 192.168.0.100#`, |
||||
want: &Config{ |
||||
Nameservers: []netaddr.IP{ |
||||
netaddr.MustParseIP("192.168.0.100"), |
||||
}, |
||||
}, |
||||
}, |
||||
{in: `nameserver #192.168.0.100`, wantErr: true}, |
||||
{in: `nameserver`, wantErr: true}, |
||||
{in: `# nameserver 192.168.0.100`, want: &Config{}}, |
||||
{in: `nameserver192.168.0.100`, wantErr: true}, |
||||
|
||||
{in: `search tailsacle.com`, |
||||
want: &Config{ |
||||
SearchDomains: []dnsname.FQDN{"tailsacle.com."}, |
||||
}, |
||||
}, |
||||
{in: `search tailsacle.com # typo`, |
||||
want: &Config{ |
||||
SearchDomains: []dnsname.FQDN{"tailsacle.com."}, |
||||
}, |
||||
}, |
||||
{in: `searchtailsacle.com`, wantErr: true}, |
||||
{in: `search`, wantErr: true}, |
||||
} |
||||
|
||||
for _, tt := range tests { |
||||
cfg, err := Parse(strings.NewReader(tt.in)) |
||||
if tt.wantErr { |
||||
if err != nil { |
||||
continue |
||||
} |
||||
t.Errorf("missing error for %q", tt.in) |
||||
continue |
||||
} |
||||
if err != nil { |
||||
t.Errorf("unexpected error for %q: %v", tt.in, err) |
||||
continue |
||||
} |
||||
if !reflect.DeepEqual(cfg, tt.want) { |
||||
t.Errorf("got: %v\nwant: %v\n", cfg, tt.want) |
||||
} |
||||
} |
||||
} |
||||
Loading…
Reference in new issue