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// Copyright 2009 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.

// IP sockets stubs for Plan 9

package net

import (
        "errors"
        "io"
        "os"
        "time"
)

// probeIPv6Stack returns two boolean values.  If the first boolean value is
// true, kernel supports basic IPv6 functionality.  If the second
// boolean value is true, kernel supports IPv6 IPv4-mapping.
func probeIPv6Stack() (supportsIPv6, supportsIPv4map bool) {
        return false, false
}

// parsePlan9Addr parses address of the form [ip!]port (e.g. 127.0.0.1!80).
func parsePlan9Addr(s string) (ip IP, iport int, err error) {
        addr := IPv4zero // address contains port only
        i := byteIndex(s, '!')
        if i >= 0 {
                addr = ParseIP(s[:i])
                if addr == nil {
                        return nil, 0, errors.New("net: parsing IP failed")
                }
        }
        p, _, ok := dtoi(s[i+1:], 0)
        if !ok {
                return nil, 0, errors.New("net: parsing port failed")
        }
        if p < 0 || p > 0xFFFF {
                return nil, 0, &AddrError{"invalid port", string(p)}
        }
        return addr, p, nil
}

func readPlan9Addr(proto, filename string) (addr Addr, err error) {
        var buf [128]byte

        f, err := os.Open(filename)
        if err != nil {
                return
        }
        n, err := f.Read(buf[:])
        if err != nil {
                return
        }
        ip, port, err := parsePlan9Addr(string(buf[:n]))
        if err != nil {
                return
        }
        switch proto {
        case "tcp":
                addr = &TCPAddr{ip, port}
        case "udp":
                addr = &UDPAddr{ip, port}
        default:
                return nil, errors.New("unknown protocol " + proto)
        }
        return addr, nil
}

type plan9Conn struct {
        proto, name, dir string
        ctl, data        *os.File
        laddr, raddr     Addr
}

func newPlan9Conn(proto, name string, ctl *os.File, laddr, raddr Addr) *plan9Conn {
        return &plan9Conn{proto, name, "/net/" + proto + "/" + name, ctl, nil, laddr, raddr}
}

func (c *plan9Conn) ok() bool { return c != nil && c.ctl != nil }

// Implementation of the Conn interface - see Conn for documentation.

// Read implements the Conn Read method.
func (c *plan9Conn) Read(b []byte) (n int, err error) {
        if !c.ok() {
                return 0, os.EINVAL
        }
        if c.data == nil {
                c.data, err = os.OpenFile(c.dir+"/data", os.O_RDWR, 0)
                if err != nil {
                        return 0, err
                }
        }
        n, err = c.data.Read(b)
        if c.proto == "udp" && err == io.EOF {
                n = 0
                err = nil
        }
        return
}

// Write implements the Conn Write method.
func (c *plan9Conn) Write(b []byte) (n int, err error) {
        if !c.ok() {
                return 0, os.EINVAL
        }
        if c.data == nil {
                c.data, err = os.OpenFile(c.dir+"/data", os.O_RDWR, 0)
                if err != nil {
                        return 0, err
                }
        }
        return c.data.Write(b)
}

// Close closes the connection.
func (c *plan9Conn) Close() error {
        if !c.ok() {
                return os.EINVAL
        }
        err := c.ctl.Close()
        if err != nil {
                return err
        }
        if c.data != nil {
                err = c.data.Close()
        }
        c.ctl = nil
        c.data = nil
        return err
}

// LocalAddr returns the local network address.
func (c *plan9Conn) LocalAddr() Addr {
        if !c.ok() {
                return nil
        }
        return c.laddr
}

// RemoteAddr returns the remote network address.
func (c *plan9Conn) RemoteAddr() Addr {
        if !c.ok() {
                return nil
        }
        return c.raddr
}

// SetDeadline implements the Conn SetDeadline method.
func (c *plan9Conn) SetDeadline(t time.Time) error {
        return os.EPLAN9
}

// SetReadDeadline implements the Conn SetReadDeadline method.
func (c *plan9Conn) SetReadDeadline(t time.Time) error {
        return os.EPLAN9
}

// SetWriteDeadline implements the Conn SetWriteDeadline method.
func (c *plan9Conn) SetWriteDeadline(t time.Time) error {
        return os.EPLAN9
}

func startPlan9(net string, addr Addr) (ctl *os.File, dest, proto, name string, err error) {
        var (
                ip   IP
                port int
        )
        switch a := addr.(type) {
        case *TCPAddr:
                proto = "tcp"
                ip = a.IP
                port = a.Port
        case *UDPAddr:
                proto = "udp"
                ip = a.IP
                port = a.Port
        default:
                err = UnknownNetworkError(net)
                return
        }

        clone, dest, err := queryCS1(proto, ip, port)
        if err != nil {
                return
        }
        f, err := os.OpenFile(clone, os.O_RDWR, 0)
        if err != nil {
                return
        }
        var buf [16]byte
        n, err := f.Read(buf[:])
        if err != nil {
                return
        }
        return f, dest, proto, string(buf[:n]), nil
}

func dialPlan9(net string, laddr, raddr Addr) (c *plan9Conn, err error) {
        f, dest, proto, name, err := startPlan9(net, raddr)
        if err != nil {
                return
        }
        _, err = f.WriteString("connect " + dest)
        if err != nil {
                return
        }
        laddr, err = readPlan9Addr(proto, "/net/"+proto+"/"+name+"/local")
        if err != nil {
                return
        }
        raddr, err = readPlan9Addr(proto, "/net/"+proto+"/"+name+"/remote")
        if err != nil {
                return
        }
        return newPlan9Conn(proto, name, f, laddr, raddr), nil
}

type plan9Listener struct {
        proto, name, dir string
        ctl              *os.File
        laddr            Addr
}

func listenPlan9(net string, laddr Addr) (l *plan9Listener, err error) {
        f, dest, proto, name, err := startPlan9(net, laddr)
        if err != nil {
                return
        }
        _, err = f.WriteString("announce " + dest)
        if err != nil {
                return
        }
        laddr, err = readPlan9Addr(proto, "/net/"+proto+"/"+name+"/local")
        if err != nil {
                return
        }
        l = new(plan9Listener)
        l.proto = proto
        l.name = name
        l.dir = "/net/" + proto + "/" + name
        l.ctl = f
        l.laddr = laddr
        return l, nil
}

func (l *plan9Listener) plan9Conn() *plan9Conn {
        return newPlan9Conn(l.proto, l.name, l.ctl, l.laddr, nil)
}

func (l *plan9Listener) acceptPlan9() (c *plan9Conn, err error) {
        f, err := os.Open(l.dir + "/listen")
        if err != nil {
                return
        }
        var buf [16]byte
        n, err := f.Read(buf[:])
        if err != nil {
                return
        }
        name := string(buf[:n])
        laddr, err := readPlan9Addr(l.proto, l.dir+"/local")
        if err != nil {
                return
        }
        raddr, err := readPlan9Addr(l.proto, l.dir+"/remote")
        if err != nil {
                return
        }
        return newPlan9Conn(l.proto, name, f, laddr, raddr), nil
}

func (l *plan9Listener) Accept() (c Conn, err error) {
        c1, err := l.acceptPlan9()
        if err != nil {
                return
        }
        return c1, nil
}

func (l *plan9Listener) Close() error {
        if l == nil || l.ctl == nil {
                return os.EINVAL
        }
        return l.ctl.Close()
}

func (l *plan9Listener) Addr() Addr { return l.laddr }