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// Copyright 2011 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 net
import (
"errors"
"os"
"syscall"
)
func query(filename, query string, bufSize int) (res []string, err error) {
file, err := os.OpenFile(filename, os.O_RDWR, 0)
if err != nil {
return
}
defer file.Close()
_, err = file.WriteString(query)
if err != nil {
return
}
_, err = file.Seek(0, 0)
if err != nil {
return
}
buf := make([]byte, bufSize)
for {
n, _ := file.Read(buf)
if n <= 0 {
break
}
res = append(res, string(buf[:n]))
}
return
}
func queryCS(net, host, service string) (res []string, err error) {
switch net {
case "tcp4", "tcp6":
net = "tcp"
case "udp4", "udp6":
net = "udp"
}
if host == "" {
host = "*"
}
return query("/net/cs", net+"!"+host+"!"+service, 128)
}
func queryCS1(net string, ip IP, port int) (clone, dest string, err error) {
ips := "*"
if len(ip) != 0 && !ip.IsUnspecified() {
ips = ip.String()
}
lines, err := queryCS(net, ips, itoa(port))
if err != nil {
return
}
f := getFields(lines[0])
if len(f) < 2 {
return "", "", errors.New("net: bad response from ndb/cs")
}
clone, dest = f[0], f[1]
return
}
func queryDNS(addr string, typ string) (res []string, err error) {
return query("/net/dns", addr+" "+typ, 1024)
}
func lookupProtocol(name string) (proto int, err error) {
// TODO: Implement this
return 0, syscall.EPLAN9
}
func lookupHost(host string) (addrs []string, err error) {
// Use /net/cs instead of /net/dns because cs knows about
// host names in local network (e.g. from /lib/ndb/local)
lines, err := queryCS("tcp", host, "1")
if err != nil {
return
}
for _, line := range lines {
f := getFields(line)
if len(f) < 2 {
continue
}
addr := f[1]
if i := byteIndex(addr, '!'); i >= 0 {
addr = addr[:i] // remove port
}
if ParseIP(addr) == nil {
continue
}
addrs = append(addrs, addr)
}
return
}
func lookupIP(host string) (ips []IP, err error) {
addrs, err := LookupHost(host)
if err != nil {
return
}
for _, addr := range addrs {
if ip := ParseIP(addr); ip != nil {
ips = append(ips, ip)
}
}
return
}
func lookupPort(network, service string) (port int, err error) {
switch network {
case "tcp4", "tcp6":
network = "tcp"
case "udp4", "udp6":
network = "udp"
}
lines, err := queryCS(network, "127.0.0.1", service)
if err != nil {
return
}
unknownPortError := &AddrError{"unknown port", network + "/" + service}
if len(lines) == 0 {
return 0, unknownPortError
}
f := getFields(lines[0])
if len(f) < 2 {
return 0, unknownPortError
}
s := f[1]
if i := byteIndex(s, '!'); i >= 0 {
s = s[i+1:] // remove address
}
if n, _, ok := dtoi(s, 0); ok {
return n, nil
}
return 0, unknownPortError
}
func lookupCNAME(name string) (cname string, err error) {
lines, err := queryDNS(name, "cname")
if err != nil {
return
}
if len(lines) > 0 {
if f := getFields(lines[0]); len(f) >= 3 {
return f[2] + ".", nil
}
}
return "", errors.New("net: bad response from ndb/dns")
}
func lookupSRV(service, proto, name string) (cname string, addrs []*SRV, err error) {
var target string
if service == "" && proto == "" {
target = name
} else {
target = "_" + service + "._" + proto + "." + name
}
lines, err := queryDNS(target, "srv")
if err != nil {
return
}
for _, line := range lines {
f := getFields(line)
if len(f) < 6 {
continue
}
port, _, portOk := dtoi(f[2], 0)
priority, _, priorityOk := dtoi(f[3], 0)
weight, _, weightOk := dtoi(f[4], 0)
if !(portOk && priorityOk && weightOk) {
continue
}
addrs = append(addrs, &SRV{f[5], uint16(port), uint16(priority), uint16(weight)})
cname = f[0]
}
byPriorityWeight(addrs).sort()
return
}
func lookupMX(name string) (mx []*MX, err error) {
lines, err := queryDNS(name, "mx")
if err != nil {
return
}
for _, line := range lines {
f := getFields(line)
if len(f) < 4 {
continue
}
if pref, _, ok := dtoi(f[2], 0); ok {
mx = append(mx, &MX{f[3], uint16(pref)})
}
}
byPref(mx).sort()
return
}
func lookupNS(name string) (ns []*NS, err error) {
lines, err := queryDNS(name, "ns")
if err != nil {
return
}
for _, line := range lines {
f := getFields(line)
if len(f) < 4 {
continue
}
ns = append(ns, &NS{f[3]})
}
return
}
func lookupTXT(name string) (txt []string, err error) {
lines, err := queryDNS(name, "txt")
if err != nil {
return
}
for _, line := range lines {
if i := byteIndex(line, '\t'); i >= 0 {
txt = append(txt, line[i+1:])
}
}
return
}
func lookupAddr(addr string) (name []string, err error) {
arpa, err := reverseaddr(addr)
if err != nil {
return
}
lines, err := queryDNS(arpa, "ptr")
if err != nil {
return
}
for _, line := range lines {
f := getFields(line)
if len(f) < 3 {
continue
}
name = append(name, f[2])
}
return
}
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