mirror of
https://github.com/mjl-/mox.git
synced 2025-06-28 07:08:14 +03:00
58 lines
2.2 KiB
Go
58 lines
2.2 KiB
Go
// Copyright 2022 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 adns
|
|
|
|
import (
|
|
"os"
|
|
"sync/atomic"
|
|
"time"
|
|
)
|
|
|
|
// defaultNS is the default name servers to use in the absence of DNS configuration.
|
|
//
|
|
// defaultNS should be an internal detail,
|
|
// but widely used packages access it using linkname.
|
|
// Notable members of the hall of shame include:
|
|
// - github.com/pojntfx/hydrapp/hydrapp
|
|
// - github.com/mtibben/androiddnsfix
|
|
// - github.com/metacubex/mihomo
|
|
//
|
|
// Do not remove or change the type signature.
|
|
// See go.dev/issue/67401.
|
|
//
|
|
// disabled: go:linkname defaultNS
|
|
var defaultNS = []string{"127.0.0.1:53", "[::1]:53"}
|
|
|
|
var getHostname = os.Hostname // variable for testing
|
|
|
|
type dnsConfig struct {
|
|
servers []string // server addresses (in host:port form) to use
|
|
search []string // rooted suffixes to append to local name
|
|
ndots int // number of dots in name to trigger absolute lookup
|
|
timeout time.Duration // wait before giving up on a query, including retries
|
|
attempts int // lost packets before giving up on server
|
|
rotate bool // round robin among servers
|
|
unknownOpt bool // anything unknown was encountered
|
|
lookup []string // OpenBSD top-level database "lookup" order
|
|
err error // any error that occurs during open of resolv.conf
|
|
mtime time.Time // time of resolv.conf modification
|
|
soffset uint32 // used by serverOffset
|
|
singleRequest bool // use sequential A and AAAA queries instead of parallel queries
|
|
useTCP bool // force usage of TCP for DNS resolutions
|
|
trustAD bool // add AD flag to queries
|
|
noReload bool // do not check for config file updates
|
|
}
|
|
|
|
// serverOffset returns an offset that can be used to determine
|
|
// indices of servers in c.servers when making queries.
|
|
// When the rotate option is enabled, this offset increases.
|
|
// Otherwise it is always 0.
|
|
func (c *dnsConfig) serverOffset() uint32 {
|
|
if c.rotate {
|
|
return atomic.AddUint32(&c.soffset, 1) - 1 // return 0 to start
|
|
}
|
|
return 0
|
|
}
|