mirror of
https://github.com/golang/go
synced 2024-10-04 21:11:22 -06:00
127 lines
3.3 KiB
Go
127 lines
3.3 KiB
Go
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// Copyright 2011 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package net
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import (
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"os"
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"rand"
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"sort"
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)
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// LookupHost looks up the given host using the local resolver.
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// It returns an array of that host's addresses.
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func LookupHost(host string) (addrs []string, err os.Error) {
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addrs, err, ok := cgoLookupHost(host)
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if !ok {
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addrs, err = goLookupHost(host)
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}
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return
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}
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// LookupIP looks up host using the local resolver.
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// It returns an array of that host's IPv4 and IPv6 addresses.
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func LookupIP(host string) (addrs []IP, err os.Error) {
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addrs, err, ok := cgoLookupIP(host)
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if !ok {
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addrs, err = goLookupIP(host)
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}
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return
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}
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// LookupPort looks up the port for the given network and service.
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func LookupPort(network, service string) (port int, err os.Error) {
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port, err, ok := cgoLookupPort(network, service)
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if !ok {
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port, err = goLookupPort(network, service)
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}
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return
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}
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// LookupCNAME returns the canonical DNS host for the given name.
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// Callers that do not care about the canonical name can call
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// LookupHost or LookupIP directly; both take care of resolving
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// the canonical name as part of the lookup.
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func LookupCNAME(name string) (cname string, err os.Error) {
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cname, err, ok := cgoLookupCNAME(name)
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if !ok {
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cname, err = goLookupCNAME(name)
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}
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return
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}
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// LookupSRV tries to resolve an SRV query of the given service,
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// protocol, and domain name, as specified in RFC 2782. In most cases
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// the proto argument can be the same as the corresponding
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// Addr.Network(). The returned records are sorted by priority
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// and randomized by weight within a priority.
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func LookupSRV(service, proto, name string) (cname string, addrs []*SRV, err os.Error) {
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target := "_" + service + "._" + proto + "." + name
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var records []dnsRR
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cname, records, err = lookup(target, dnsTypeSRV)
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if err != nil {
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return
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}
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addrs = make([]*SRV, len(records))
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for i, rr := range records {
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r := rr.(*dnsRR_SRV)
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addrs[i] = &SRV{r.Target, r.Port, r.Priority, r.Weight}
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}
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sort.Sort(byPriorityWeight(addrs))
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i := 0
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for j := 1; j < len(addrs); j++ {
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if addrs[i].Priority != addrs[j].Priority {
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shuffleSRVByWeight(addrs[i:j])
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i = j
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}
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}
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shuffleSRVByWeight(addrs[i:len(addrs)])
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return
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}
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// LookupMX returns the DNS MX records for the given domain name sorted by preference.
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func LookupMX(name string) (mx []*MX, err os.Error) {
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_, rr, err := lookup(name, dnsTypeMX)
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if err != nil {
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return
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}
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mx = make([]*MX, len(rr))
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for i := range rr {
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r := rr[i].(*dnsRR_MX)
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mx[i] = &MX{r.Mx, r.Pref}
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}
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// Shuffle the records to match RFC 5321 when sorted
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for i := range mx {
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j := rand.Intn(i + 1)
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mx[i], mx[j] = mx[j], mx[i]
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}
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sort.Sort(byPref(mx))
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return
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}
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// LookupAddr performs a reverse lookup for the given address, returning a list
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// of names mapping to that address.
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func LookupAddr(addr string) (name []string, err os.Error) {
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name = lookupStaticAddr(addr)
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if len(name) > 0 {
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return
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}
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var arpa string
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arpa, err = reverseaddr(addr)
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if err != nil {
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return
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}
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var records []dnsRR
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_, records, err = lookup(arpa, dnsTypePTR)
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if err != nil {
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return
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}
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name = make([]string, len(records))
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for i := range records {
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r := records[i].(*dnsRR_PTR)
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name[i] = r.Ptr
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}
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return
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}
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