mirror of
https://github.com/golang/go
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3a9024b498
It's a single, package-wide init function specified for the net package. Change-Id: Id5894d65e1a92297cc16803cc5e4d4eef0b4b099 Reviewed-on: https://go-review.googlesource.com/8391 Reviewed-by: Ian Lance Taylor <iant@golang.org>
305 lines
7.8 KiB
Go
305 lines
7.8 KiB
Go
// Copyright 2009 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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// Internet protocol family sockets
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package net
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import (
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"errors"
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"time"
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)
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var (
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// supportsIPv4 reports whether the platform supports IPv4
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// networking functionality.
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supportsIPv4 bool
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// supportsIPv6 reports whether the platform supports IPv6
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// networking functionality.
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supportsIPv6 bool
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// supportsIPv4map reports whether the platform supports
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// mapping an IPv4 address inside an IPv6 address at transport
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// layer protocols. See RFC 4291, RFC 4038 and RFC 3493.
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supportsIPv4map bool
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)
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// A netaddr represents a network endpoint address or a list of
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// network endpoint addresses.
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type netaddr interface {
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// toAddr returns the address represented in Addr interface.
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// It returns a nil interface when the address is nil.
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toAddr() Addr
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}
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// An addrList represents a list of network endpoint addresses.
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type addrList []netaddr
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func (al addrList) toAddr() Addr {
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switch len(al) {
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case 0:
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return nil
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case 1:
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return al[0].toAddr()
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default:
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// For now, we'll roughly pick first one without
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// considering dealing with any preferences such as
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// DNS TTL, transport path quality, network routing
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// information.
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return al[0].toAddr()
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}
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}
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var errNoSuitableAddress = errors.New("no suitable address found")
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// firstFavoriteAddr returns an address or a list of addresses that
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// implement the netaddr interface. Known filters are nil, ipv4only
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// and ipv6only. It returns any address when filter is nil. The result
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// contains at least one address when error is nil.
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func firstFavoriteAddr(filter func(IPAddr) bool, ips []IPAddr, inetaddr func(IPAddr) netaddr) (netaddr, error) {
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if filter != nil {
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return firstSupportedAddr(filter, ips, inetaddr)
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}
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var (
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ipv4, ipv6, swap bool
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list addrList
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)
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for _, ip := range ips {
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// We'll take any IP address, but since the dialing
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// code does not yet try multiple addresses
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// effectively, prefer to use an IPv4 address if
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// possible. This is especially relevant if localhost
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// resolves to [ipv6-localhost, ipv4-localhost]. Too
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// much code assumes localhost == ipv4-localhost.
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if ipv4only(ip) && !ipv4 {
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list = append(list, inetaddr(ip))
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ipv4 = true
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if ipv6 {
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swap = true
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}
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} else if ipv6only(ip) && !ipv6 {
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list = append(list, inetaddr(ip))
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ipv6 = true
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}
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if ipv4 && ipv6 {
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if swap {
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list[0], list[1] = list[1], list[0]
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}
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break
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}
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}
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switch len(list) {
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case 0:
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return nil, errNoSuitableAddress
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case 1:
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return list[0], nil
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default:
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return list, nil
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}
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}
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func firstSupportedAddr(filter func(IPAddr) bool, ips []IPAddr, inetaddr func(IPAddr) netaddr) (netaddr, error) {
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for _, ip := range ips {
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if filter(ip) {
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return inetaddr(ip), nil
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}
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}
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return nil, errNoSuitableAddress
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}
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// ipv4only reports whether the kernel supports IPv4 addressing mode
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// and addr is an IPv4 address.
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func ipv4only(addr IPAddr) bool {
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return supportsIPv4 && addr.IP.To4() != nil
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}
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// ipv6only reports whether the kernel supports IPv6 addressing mode
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// and addr is an IPv6 address except IPv4-mapped IPv6 address.
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func ipv6only(addr IPAddr) bool {
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return supportsIPv6 && len(addr.IP) == IPv6len && addr.IP.To4() == nil
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}
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// SplitHostPort splits a network address of the form "host:port",
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// "[host]:port" or "[ipv6-host%zone]:port" into host or
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// ipv6-host%zone and port. A literal address or host name for IPv6
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// must be enclosed in square brackets, as in "[::1]:80",
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// "[ipv6-host]:http" or "[ipv6-host%zone]:80".
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func SplitHostPort(hostport string) (host, port string, err error) {
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j, k := 0, 0
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// The port starts after the last colon.
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i := last(hostport, ':')
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if i < 0 {
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goto missingPort
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}
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if hostport[0] == '[' {
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// Expect the first ']' just before the last ':'.
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end := byteIndex(hostport, ']')
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if end < 0 {
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err = &AddrError{"missing ']' in address", hostport}
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return
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}
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switch end + 1 {
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case len(hostport):
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// There can't be a ':' behind the ']' now.
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goto missingPort
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case i:
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// The expected result.
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default:
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// Either ']' isn't followed by a colon, or it is
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// followed by a colon that is not the last one.
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if hostport[end+1] == ':' {
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goto tooManyColons
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}
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goto missingPort
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}
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host = hostport[1:end]
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j, k = 1, end+1 // there can't be a '[' resp. ']' before these positions
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} else {
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host = hostport[:i]
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if byteIndex(host, ':') >= 0 {
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goto tooManyColons
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}
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if byteIndex(host, '%') >= 0 {
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goto missingBrackets
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}
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}
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if byteIndex(hostport[j:], '[') >= 0 {
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err = &AddrError{"unexpected '[' in address", hostport}
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return
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}
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if byteIndex(hostport[k:], ']') >= 0 {
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err = &AddrError{"unexpected ']' in address", hostport}
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return
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}
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port = hostport[i+1:]
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return
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missingPort:
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err = &AddrError{"missing port in address", hostport}
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return
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tooManyColons:
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err = &AddrError{"too many colons in address", hostport}
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return
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missingBrackets:
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err = &AddrError{"missing brackets in address", hostport}
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return
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}
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func splitHostZone(s string) (host, zone string) {
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// The IPv6 scoped addressing zone identifier starts after the
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// last percent sign.
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if i := last(s, '%'); i > 0 {
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host, zone = s[:i], s[i+1:]
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} else {
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host = s
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}
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return
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}
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// JoinHostPort combines host and port into a network address of the
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// form "host:port" or, if host contains a colon or a percent sign,
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// "[host]:port".
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func JoinHostPort(host, port string) string {
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// If host has colons or a percent sign, have to bracket it.
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if byteIndex(host, ':') >= 0 || byteIndex(host, '%') >= 0 {
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return "[" + host + "]:" + port
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}
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return host + ":" + port
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}
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// resolveInternetAddr resolves addr that is either a literal IP
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// address or a DNS name and returns an internet protocol family
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// address. It returns a list that contains a pair of different
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// address family addresses when addr is a DNS name and the name has
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// multiple address family records. The result contains at least one
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// address when error is nil.
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func resolveInternetAddr(net, addr string, deadline time.Time) (netaddr, error) {
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var (
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err error
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host, port string
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portnum int
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)
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switch net {
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case "tcp", "tcp4", "tcp6", "udp", "udp4", "udp6":
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if addr != "" {
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if host, port, err = SplitHostPort(addr); err != nil {
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return nil, err
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}
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if portnum, err = parsePort(net, port); err != nil {
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return nil, err
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}
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}
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case "ip", "ip4", "ip6":
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if addr != "" {
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host = addr
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}
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default:
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return nil, UnknownNetworkError(net)
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}
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inetaddr := func(ip IPAddr) netaddr {
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switch net {
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case "tcp", "tcp4", "tcp6":
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return &TCPAddr{IP: ip.IP, Port: portnum, Zone: ip.Zone}
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case "udp", "udp4", "udp6":
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return &UDPAddr{IP: ip.IP, Port: portnum, Zone: ip.Zone}
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case "ip", "ip4", "ip6":
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return &IPAddr{IP: ip.IP, Zone: ip.Zone}
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default:
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panic("unexpected network: " + net)
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}
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}
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if host == "" {
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return inetaddr(IPAddr{}), nil
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}
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// Try as a literal IP address.
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var ip IP
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if ip = parseIPv4(host); ip != nil {
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return inetaddr(IPAddr{IP: ip}), nil
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}
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var zone string
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if ip, zone = parseIPv6(host, true); ip != nil {
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return inetaddr(IPAddr{IP: ip, Zone: zone}), nil
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}
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// Try as a DNS name.
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ips, err := lookupIPDeadline(host, deadline)
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if err != nil {
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return nil, err
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}
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var filter func(IPAddr) bool
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if net != "" && net[len(net)-1] == '4' {
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filter = ipv4only
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}
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if net != "" && net[len(net)-1] == '6' {
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filter = ipv6only
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}
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return firstFavoriteAddr(filter, ips, inetaddr)
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}
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func zoneToString(zone int) string {
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if zone == 0 {
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return ""
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}
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if ifi, err := InterfaceByIndex(zone); err == nil {
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return ifi.Name
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}
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return uitoa(uint(zone))
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}
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func zoneToInt(zone string) int {
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if zone == "" {
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return 0
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}
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if ifi, err := InterfaceByName(zone); err == nil {
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return ifi.Index
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}
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n, _, _ := dtoi(zone, 0)
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return n
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}
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