1// Copyright 2009 The Go Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4
5package net
6
7import (
8	"context"
9	"internal/bytealg"
10	"internal/itoa"
11	"io/fs"
12	"os"
13	"syscall"
14)
15
16// probe probes IPv4, IPv6 and IPv4-mapped IPv6 communication
17// capabilities.
18//
19// Plan 9 uses IPv6 natively, see ip(3).
20func (p *ipStackCapabilities) probe() {
21	p.ipv4Enabled = probe(netdir+"/iproute", "4i")
22	p.ipv6Enabled = probe(netdir+"/iproute", "6i")
23	if p.ipv4Enabled && p.ipv6Enabled {
24		p.ipv4MappedIPv6Enabled = true
25	}
26}
27
28func probe(filename, query string) bool {
29	var file *file
30	var err error
31	if file, err = open(filename); err != nil {
32		return false
33	}
34	defer file.close()
35
36	r := false
37	for line, ok := file.readLine(); ok && !r; line, ok = file.readLine() {
38		f := getFields(line)
39		if len(f) < 3 {
40			continue
41		}
42		for i := 0; i < len(f); i++ {
43			if query == f[i] {
44				r = true
45				break
46			}
47		}
48	}
49	return r
50}
51
52// parsePlan9Addr parses address of the form [ip!]port (e.g. 127.0.0.1!80).
53func parsePlan9Addr(s string) (ip IP, iport int, err error) {
54	addr := IPv4zero // address contains port only
55	i := bytealg.IndexByteString(s, '!')
56	if i >= 0 {
57		addr = ParseIP(s[:i])
58		if addr == nil {
59			return nil, 0, &ParseError{Type: "IP address", Text: s}
60		}
61	}
62	p, plen, ok := dtoi(s[i+1:])
63	if !ok {
64		return nil, 0, &ParseError{Type: "port", Text: s}
65	}
66	if p < 0 || p > 0xFFFF {
67		return nil, 0, &AddrError{Err: "invalid port", Addr: s[i+1 : i+1+plen]}
68	}
69	return addr, p, nil
70}
71
72func readPlan9Addr(net, filename string) (addr Addr, err error) {
73	var buf [128]byte
74
75	f, err := os.Open(filename)
76	if err != nil {
77		return
78	}
79	defer f.Close()
80	n, err := f.Read(buf[:])
81	if err != nil {
82		return
83	}
84	ip, port, err := parsePlan9Addr(string(buf[:n]))
85	if err != nil {
86		return
87	}
88	switch net {
89	case "tcp4", "udp4":
90		if ip.Equal(IPv6zero) {
91			ip = ip[:IPv4len]
92		}
93	}
94	switch net {
95	case "tcp", "tcp4", "tcp6":
96		addr = &TCPAddr{IP: ip, Port: port}
97	case "udp", "udp4", "udp6":
98		addr = &UDPAddr{IP: ip, Port: port}
99	default:
100		return nil, UnknownNetworkError(net)
101	}
102	return addr, nil
103}
104
105func startPlan9(ctx context.Context, net string, addr Addr) (ctl *os.File, dest, proto, name string, err error) {
106	var (
107		ip   IP
108		port int
109	)
110	switch a := addr.(type) {
111	case *TCPAddr:
112		proto = "tcp"
113		ip = a.IP
114		port = a.Port
115	case *UDPAddr:
116		proto = "udp"
117		ip = a.IP
118		port = a.Port
119	default:
120		err = UnknownNetworkError(net)
121		return
122	}
123
124	if port > 65535 {
125		err = InvalidAddrError("port should be < 65536")
126		return
127	}
128
129	clone, dest, err := queryCS1(ctx, proto, ip, port)
130	if err != nil {
131		return
132	}
133	f, err := os.OpenFile(clone, os.O_RDWR, 0)
134	if err != nil {
135		return
136	}
137	var buf [16]byte
138	n, err := f.Read(buf[:])
139	if err != nil {
140		f.Close()
141		return
142	}
143	return f, dest, proto, string(buf[:n]), nil
144}
145
146func fixErr(err error) {
147	oe, ok := err.(*OpError)
148	if !ok {
149		return
150	}
151	nonNilInterface := func(a Addr) bool {
152		switch a := a.(type) {
153		case *TCPAddr:
154			return a == nil
155		case *UDPAddr:
156			return a == nil
157		case *IPAddr:
158			return a == nil
159		default:
160			return false
161		}
162	}
163	if nonNilInterface(oe.Source) {
164		oe.Source = nil
165	}
166	if nonNilInterface(oe.Addr) {
167		oe.Addr = nil
168	}
169	if pe, ok := oe.Err.(*fs.PathError); ok {
170		if _, ok = pe.Err.(syscall.ErrorString); ok {
171			oe.Err = pe.Err
172		}
173	}
174}
175
176func dialPlan9(ctx context.Context, net string, laddr, raddr Addr) (fd *netFD, err error) {
177	defer func() { fixErr(err) }()
178	type res struct {
179		fd  *netFD
180		err error
181	}
182	resc := make(chan res)
183	go func() {
184		fd, err := dialPlan9Blocking(ctx, net, laddr, raddr)
185		select {
186		case resc <- res{fd, err}:
187		case <-ctx.Done():
188			if fd != nil {
189				fd.Close()
190			}
191		}
192	}()
193	select {
194	case res := <-resc:
195		return res.fd, res.err
196	case <-ctx.Done():
197		return nil, mapErr(ctx.Err())
198	}
199}
200
201func dialPlan9Blocking(ctx context.Context, net string, laddr, raddr Addr) (fd *netFD, err error) {
202	if isWildcard(raddr) {
203		raddr = toLocal(raddr, net)
204	}
205	f, dest, proto, name, err := startPlan9(ctx, net, raddr)
206	if err != nil {
207		return nil, err
208	}
209	if la := plan9LocalAddr(laddr); la == "" {
210		err = hangupCtlWrite(ctx, proto, f, "connect "+dest)
211	} else {
212		err = hangupCtlWrite(ctx, proto, f, "connect "+dest+" "+la)
213	}
214	if err != nil {
215		f.Close()
216		return nil, err
217	}
218	data, err := os.OpenFile(netdir+"/"+proto+"/"+name+"/data", os.O_RDWR, 0)
219	if err != nil {
220		f.Close()
221		return nil, err
222	}
223	laddr, err = readPlan9Addr(net, netdir+"/"+proto+"/"+name+"/local")
224	if err != nil {
225		data.Close()
226		f.Close()
227		return nil, err
228	}
229	return newFD(proto, name, nil, f, data, laddr, raddr)
230}
231
232func listenPlan9(ctx context.Context, net string, laddr Addr) (fd *netFD, err error) {
233	defer func() { fixErr(err) }()
234	f, dest, proto, name, err := startPlan9(ctx, net, laddr)
235	if err != nil {
236		return nil, err
237	}
238	_, err = f.WriteString("announce " + dest)
239	if err != nil {
240		f.Close()
241		return nil, &OpError{Op: "announce", Net: net, Source: laddr, Addr: nil, Err: err}
242	}
243	laddr, err = readPlan9Addr(net, netdir+"/"+proto+"/"+name+"/local")
244	if err != nil {
245		f.Close()
246		return nil, err
247	}
248	return newFD(proto, name, nil, f, nil, laddr, nil)
249}
250
251func (fd *netFD) netFD() (*netFD, error) {
252	return newFD(fd.net, fd.n, fd.listen, fd.ctl, fd.data, fd.laddr, fd.raddr)
253}
254
255func (fd *netFD) acceptPlan9() (nfd *netFD, err error) {
256	defer func() { fixErr(err) }()
257	if err := fd.pfd.ReadLock(); err != nil {
258		return nil, err
259	}
260	defer fd.pfd.ReadUnlock()
261	listen, err := os.Open(fd.dir + "/listen")
262	if err != nil {
263		return nil, err
264	}
265	var buf [16]byte
266	n, err := listen.Read(buf[:])
267	if err != nil {
268		listen.Close()
269		return nil, err
270	}
271	name := string(buf[:n])
272	ctl, err := os.OpenFile(netdir+"/"+fd.net+"/"+name+"/ctl", os.O_RDWR, 0)
273	if err != nil {
274		listen.Close()
275		return nil, err
276	}
277	data, err := os.OpenFile(netdir+"/"+fd.net+"/"+name+"/data", os.O_RDWR, 0)
278	if err != nil {
279		listen.Close()
280		ctl.Close()
281		return nil, err
282	}
283	raddr, err := readPlan9Addr(fd.net, netdir+"/"+fd.net+"/"+name+"/remote")
284	if err != nil {
285		listen.Close()
286		ctl.Close()
287		data.Close()
288		return nil, err
289	}
290	return newFD(fd.net, name, listen, ctl, data, fd.laddr, raddr)
291}
292
293func isWildcard(a Addr) bool {
294	var wildcard bool
295	switch a := a.(type) {
296	case *TCPAddr:
297		wildcard = a.isWildcard()
298	case *UDPAddr:
299		wildcard = a.isWildcard()
300	case *IPAddr:
301		wildcard = a.isWildcard()
302	}
303	return wildcard
304}
305
306func toLocal(a Addr, net string) Addr {
307	switch a := a.(type) {
308	case *TCPAddr:
309		a.IP = loopbackIP(net)
310	case *UDPAddr:
311		a.IP = loopbackIP(net)
312	case *IPAddr:
313		a.IP = loopbackIP(net)
314	}
315	return a
316}
317
318// plan9LocalAddr returns a Plan 9 local address string.
319// See setladdrport at https://9p.io/sources/plan9/sys/src/9/ip/devip.c.
320func plan9LocalAddr(addr Addr) string {
321	var ip IP
322	port := 0
323	switch a := addr.(type) {
324	case *TCPAddr:
325		if a != nil {
326			ip = a.IP
327			port = a.Port
328		}
329	case *UDPAddr:
330		if a != nil {
331			ip = a.IP
332			port = a.Port
333		}
334	}
335	if len(ip) == 0 || ip.IsUnspecified() {
336		if port == 0 {
337			return ""
338		}
339		return itoa.Itoa(port)
340	}
341	return ip.String() + "!" + itoa.Itoa(port)
342}
343
344func hangupCtlWrite(ctx context.Context, proto string, ctl *os.File, msg string) error {
345	if proto != "tcp" {
346		_, err := ctl.WriteString(msg)
347		return err
348	}
349	written := make(chan struct{})
350	errc := make(chan error)
351	go func() {
352		select {
353		case <-ctx.Done():
354			ctl.WriteString("hangup")
355			errc <- mapErr(ctx.Err())
356		case <-written:
357			errc <- nil
358		}
359	}()
360	_, err := ctl.WriteString(msg)
361	close(written)
362	if e := <-errc; err == nil && e != nil { // we hung up
363		return e
364	}
365	return err
366}
367