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// Copyright 2010 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 (

        "time"

)

func parseDialNetwork(net string) (afnet string, proto int, err error) {

        i := last(net, ':')

        if i < 0 { // no colon

                switch net {

                case "tcp", "tcp4", "tcp6":

                case "udp", "udp4", "udp6":

                case "unix", "unixgram", "unixpacket":

                default:

                        return "", 0, UnknownNetworkError(net)

                }

                return net, 0, nil

        }

        afnet = net[:i]

        switch afnet {

        case "ip", "ip4", "ip6":

                protostr := net[i+1:]

                proto, i, ok := dtoi(protostr, 0)

                if !ok || i != len(protostr) {

                        proto, err = lookupProtocol(protostr)

                        if err != nil {

                                return "", 0, err

                        }

                }

                return afnet, proto, nil

        }

        return "", 0, UnknownNetworkError(net)

}

func resolveNetAddr(op, net, addr string) (afnet string, a Addr, err error) {

        afnet, _, err = parseDialNetwork(net)

        if err != nil {

                return "", nil, &OpError{op, net, nil, err}

        }

        if op == "dial" && addr == "" {

                return "", nil, &OpError{op, net, nil, errMissingAddress}

        }

        switch afnet {

        case "tcp", "tcp4", "tcp6":

                if addr != "" {

                        a, err = ResolveTCPAddr(afnet, addr)

                }

        case "udp", "udp4", "udp6":

                if addr != "" {

                        a, err = ResolveUDPAddr(afnet, addr)

                }

        case "ip", "ip4", "ip6":

                if addr != "" {

                        a, err = ResolveIPAddr(afnet, addr)

                }

        case "unix", "unixgram", "unixpacket":

                if addr != "" {

                        a, err = ResolveUnixAddr(afnet, addr)

                }

        }

        return

}

// Dial connects to the address addr on the network net.

//

// Known networks are "tcp", "tcp4" (IPv4-only), "tcp6" (IPv6-only),

// "udp", "udp4" (IPv4-only), "udp6" (IPv6-only), "ip", "ip4"

// (IPv4-only), "ip6" (IPv6-only), "unix", "unixgram" and "unixpacket".

//

// For TCP and UDP networks, addresses have the form host:port.

// If host is a literal IPv6 address, it must be enclosed

// in square brackets.  The functions JoinHostPort and SplitHostPort

// manipulate addresses in this form.

//

// Examples:

//      Dial("tcp", "12.34.56.78:80")

//      Dial("tcp", "google.com:80")

//      Dial("tcp", "[de:ad:be:ef::ca:fe]:80")

//

// For IP networks, addr must be "ip", "ip4" or "ip6" followed

// by a colon and a protocol number or name.

//

// Examples:

//      Dial("ip4:1", "127.0.0.1")

//      Dial("ip6:ospf", "::1")

//

func Dial(net, addr string) (Conn, error) {

        _, addri, err := resolveNetAddr("dial", net, addr)

        if err != nil {

                return nil, err

        }

        return dialAddr(net, addr, addri)

}

func dialAddr(net, addr string, addri Addr) (c Conn, err error) {

        switch ra := addri.(type) {

        case *TCPAddr:

                c, err = DialTCP(net, nil, ra)

        case *UDPAddr:

                c, err = DialUDP(net, nil, ra)

        case *IPAddr:

                c, err = DialIP(net, nil, ra)

        case *UnixAddr:

                c, err = DialUnix(net, nil, ra)

        default:

                err = &OpError{"dial", net + " " + addr, nil, UnknownNetworkError(net)}

        }

        if err != nil {

                return nil, err

        }

        return

}

// DialTimeout acts like Dial but takes a timeout.

// The timeout includes name resolution, if required.

func DialTimeout(net, addr string, timeout time.Duration) (Conn, error) {

        // TODO(bradfitz): the timeout should be pushed down into the

        // net package's event loop, so on timeout to dead hosts we

        // don't have a goroutine sticking around for the default of

        // ~3 minutes.

        t := time.NewTimer(timeout)

        defer t.Stop()

        type pair struct {

                Conn

                error

        }

        ch := make(chan pair, 1)

        resolvedAddr := make(chan Addr, 1)

        go func() {

                _, addri, err := resolveNetAddr("dial", net, addr)

                if err != nil {

                        ch <- pair{nil, err}

                        return

                }

                resolvedAddr <- addri // in case we need it for OpError

                c, err := dialAddr(net, addr, addri)

                ch <- pair{c, err}

        }()

        select {

        case <-t.C:

                // Try to use the real Addr in our OpError, if we resolved it

                // before the timeout. Otherwise we just use stringAddr.

                var addri Addr

                select {

                case a := <-resolvedAddr:

                        addri = a

                default:

                        addri = &stringAddr{net, addr}

                }

                err := &OpError{

                        Op:   "dial",

                        Net:  net,

                        Addr: addri,

                        Err:  &timeoutError{},

                }

                return nil, err

        case p := <-ch:

                return p.Conn, p.error

        }

        panic("unreachable")

}

type stringAddr struct {

        net, addr string

}

func (a stringAddr) Network() string { return a.net }

func (a stringAddr) String() string  { return a.addr }

// Listen announces on the local network address laddr.

// The network string net must be a stream-oriented network:

// "tcp", "tcp4", "tcp6", or "unix", or "unixpacket".

func Listen(net, laddr string) (Listener, error) {

        afnet, a, err := resolveNetAddr("listen", net, laddr)

        if err != nil {

                return nil, err

        }

        switch afnet {

        case "tcp", "tcp4", "tcp6":

                var la *TCPAddr

                if a != nil {

                        la = a.(*TCPAddr)

                }

                return ListenTCP(afnet, la)

        case "unix", "unixpacket":

                var la *UnixAddr

                if a != nil {

                        la = a.(*UnixAddr)

                }

                return ListenUnix(net, la)

        }

        return nil, UnknownNetworkError(net)

}

// ListenPacket announces on the local network address laddr.

// The network string net must be a packet-oriented network:

// "udp", "udp4", "udp6", "ip", "ip4", "ip6" or "unixgram".

func ListenPacket(net, addr string) (PacketConn, error) {

        afnet, a, err := resolveNetAddr("listen", net, addr)

        if err != nil {

                return nil, err

        }

        switch afnet {

        case "udp", "udp4", "udp6":

                var la *UDPAddr

                if a != nil {

                        la = a.(*UDPAddr)

                }

                return ListenUDP(net, la)

        case "ip", "ip4", "ip6":

                var la *IPAddr

                if a != nil {

                        la = a.(*IPAddr)

                }

                return ListenIP(net, la)

        case "unixgram":

                var la *UnixAddr

                if a != nil {

                        la = a.(*UnixAddr)

                }

                return DialUnix(net, la, nil)

        }

        return nil, UnknownNetworkError(net)

}