summaryrefslogtreecommitdiff
path: root/src/pkg/net/lookup_plan9.go
blob: b80ac10e0d9d0ef155c123e11fc26a031f200873 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
// 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"
)

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.Seek(0, 0)
	if err != nil {
		return
	}
	_, 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(netdir+"/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("bad response from ndb/cs")
	}
	clone, dest = f[0], f[1]
	return
}

func queryDNS(addr string, typ string) (res []string, err error) {
	return query(netdir+"/dns", addr+" "+typ, 1024)
}

// toLower returns a lower-case version of in. Restricting us to
// ASCII is sufficient to handle the IP protocol names and allow
// us to not depend on the strings and unicode packages.
func toLower(in string) string {
	for _, c := range in {
		if 'A' <= c && c <= 'Z' {
			// Has upper case; need to fix.
			out := []byte(in)
			for i := 0; i < len(in); i++ {
				c := in[i]
				if 'A' <= c && c <= 'Z' {
					c += 'a' - 'A'
				}
				out[i] = c
			}
			return string(out)
		}
	}
	return in
}

// lookupProtocol looks up IP protocol name and returns
// the corresponding protocol number.
func lookupProtocol(name string) (proto int, err error) {
	lines, err := query(netdir+"/cs", "!protocol="+toLower(name), 128)
	if err != nil {
		return 0, err
	}
	unknownProtoError := errors.New("unknown IP protocol specified: " + name)
	if len(lines) == 0 {
		return 0, unknownProtoError
	}
	f := getFields(lines[0])
	if len(f) < 2 {
		return 0, unknownProtoError
	}
	s := f[1]
	if n, _, ok := dtoi(s, byteIndex(s, '=')+1); ok {
		return n, nil
	}
	return 0, unknownProtoError
}

func lookupHost(host string) (addrs []string, err error) {
	// Use netdir/cs instead of netdir/dns because cs knows about
	// host names in local network (e.g. from /lib/ndb/local)
	lines, err := queryCS("net", host, "1")
	if err != nil {
		return
	}
loop:
	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
		}
		// only return unique addresses
		for _, a := range addrs {
			if a == addr {
				continue loop
			}
		}
		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("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[4], 0)
		priority, _, priorityOk := dtoi(f[3], 0)
		weight, _, weightOk := dtoi(f[2], 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) < 3 {
			continue
		}
		ns = append(ns, &NS{f[2]})
	}
	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
}