1 // Copyright 2012 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.
16 func ExampleListener() {
17 // Listen on TCP port 2000 on all available unicast and
18 // anycast IP addresses of the local system.
19 l, err := net.Listen("tcp", ":2000")
25 // Wait for a connection.
26 conn, err := l.Accept()
30 // Handle the connection in a new goroutine.
31 // The loop then returns to accepting, so that
32 // multiple connections may be served concurrently.
34 // Echo all incoming data.
36 // Shut down the connection.
42 func ExampleDialer() {
44 ctx, cancel := context.WithTimeout(context.Background(), time.Minute)
47 conn, err := d.DialContext(ctx, "tcp", "localhost:12345")
49 log.Fatalf("Failed to dial: %v", err)
53 if _, err := conn.Write([]byte("Hello, World!")); err != nil {
58 func ExampleDialer_unix() {
59 // DialUnix does not take a context.Context parameter. This example shows
60 // how to dial a Unix socket with a Context. Note that the Context only
61 // applies to the dial operation; it does not apply to the connection once
62 // it has been established.
64 ctx, cancel := context.WithTimeout(context.Background(), time.Minute)
67 d.LocalAddr = nil // if you have a local addr, add it here
68 raddr := net.UnixAddr{Name: "/path/to/unix.sock", Net: "unix"}
69 conn, err := d.DialContext(ctx, "unix", raddr.String())
71 log.Fatalf("Failed to dial: %v", err)
74 if _, err := conn.Write([]byte("Hello, socket!")); err != nil {
80 fmt.Println(net.IPv4(8, 8, 8, 8))
86 func ExampleParseCIDR() {
87 ipv4Addr, ipv4Net, err := net.ParseCIDR("192.0.2.1/24")
94 ipv6Addr, ipv6Net, err := net.ParseCIDR("2001:db8:a0b:12f0::1/32")
104 // 2001:db8:a0b:12f0::1
108 func ExampleParseIP() {
109 fmt.Println(net.ParseIP("192.0.2.1"))
110 fmt.Println(net.ParseIP("2001:db8::68"))
111 fmt.Println(net.ParseIP("192.0.2"))
119 func ExampleIP_DefaultMask() {
120 ip := net.ParseIP("192.0.2.1")
121 fmt.Println(ip.DefaultMask())
127 func ExampleIP_Equal() {
128 ipv4DNS := net.ParseIP("8.8.8.8")
129 ipv4Lo := net.ParseIP("127.0.0.1")
130 ipv6DNS := net.ParseIP("0:0:0:0:0:FFFF:0808:0808")
132 fmt.Println(ipv4DNS.Equal(ipv4DNS))
133 fmt.Println(ipv4DNS.Equal(ipv4Lo))
134 fmt.Println(ipv4DNS.Equal(ipv6DNS))
142 func ExampleIP_IsGlobalUnicast() {
143 ipv6Global := net.ParseIP("2000::")
144 ipv6UniqLocal := net.ParseIP("2000::")
145 ipv6Multi := net.ParseIP("FF00::")
147 ipv4Private := net.ParseIP("10.255.0.0")
148 ipv4Public := net.ParseIP("8.8.8.8")
149 ipv4Broadcast := net.ParseIP("255.255.255.255")
151 fmt.Println(ipv6Global.IsGlobalUnicast())
152 fmt.Println(ipv6UniqLocal.IsGlobalUnicast())
153 fmt.Println(ipv6Multi.IsGlobalUnicast())
155 fmt.Println(ipv4Private.IsGlobalUnicast())
156 fmt.Println(ipv4Public.IsGlobalUnicast())
157 fmt.Println(ipv4Broadcast.IsGlobalUnicast())
168 func ExampleIP_IsInterfaceLocalMulticast() {
169 ipv6InterfaceLocalMulti := net.ParseIP("ff01::1")
170 ipv6Global := net.ParseIP("2000::")
171 ipv4 := net.ParseIP("255.0.0.0")
173 fmt.Println(ipv6InterfaceLocalMulti.IsInterfaceLocalMulticast())
174 fmt.Println(ipv6Global.IsInterfaceLocalMulticast())
175 fmt.Println(ipv4.IsInterfaceLocalMulticast())
183 func ExampleIP_IsLinkLocalMulticast() {
184 ipv6LinkLocalMulti := net.ParseIP("ff02::2")
185 ipv6LinkLocalUni := net.ParseIP("fe80::")
186 ipv4LinkLocalMulti := net.ParseIP("224.0.0.0")
187 ipv4LinkLocalUni := net.ParseIP("169.254.0.0")
189 fmt.Println(ipv6LinkLocalMulti.IsLinkLocalMulticast())
190 fmt.Println(ipv6LinkLocalUni.IsLinkLocalMulticast())
191 fmt.Println(ipv4LinkLocalMulti.IsLinkLocalMulticast())
192 fmt.Println(ipv4LinkLocalUni.IsLinkLocalMulticast())
201 func ExampleIP_IsLinkLocalUnicast() {
202 ipv6LinkLocalUni := net.ParseIP("fe80::")
203 ipv6Global := net.ParseIP("2000::")
204 ipv4LinkLocalUni := net.ParseIP("169.254.0.0")
205 ipv4LinkLocalMulti := net.ParseIP("224.0.0.0")
207 fmt.Println(ipv6LinkLocalUni.IsLinkLocalUnicast())
208 fmt.Println(ipv6Global.IsLinkLocalUnicast())
209 fmt.Println(ipv4LinkLocalUni.IsLinkLocalUnicast())
210 fmt.Println(ipv4LinkLocalMulti.IsLinkLocalUnicast())
219 func ExampleIP_IsLoopback() {
220 ipv6Lo := net.ParseIP("::1")
221 ipv6 := net.ParseIP("ff02::1")
222 ipv4Lo := net.ParseIP("127.0.0.0")
223 ipv4 := net.ParseIP("128.0.0.0")
225 fmt.Println(ipv6Lo.IsLoopback())
226 fmt.Println(ipv6.IsLoopback())
227 fmt.Println(ipv4Lo.IsLoopback())
228 fmt.Println(ipv4.IsLoopback())
237 func ExampleIP_IsMulticast() {
238 ipv6Multi := net.ParseIP("FF00::")
239 ipv6LinkLocalMulti := net.ParseIP("ff02::1")
240 ipv6Lo := net.ParseIP("::1")
241 ipv4Multi := net.ParseIP("239.0.0.0")
242 ipv4LinkLocalMulti := net.ParseIP("224.0.0.0")
243 ipv4Lo := net.ParseIP("127.0.0.0")
245 fmt.Println(ipv6Multi.IsMulticast())
246 fmt.Println(ipv6LinkLocalMulti.IsMulticast())
247 fmt.Println(ipv6Lo.IsMulticast())
248 fmt.Println(ipv4Multi.IsMulticast())
249 fmt.Println(ipv4LinkLocalMulti.IsMulticast())
250 fmt.Println(ipv4Lo.IsMulticast())
261 func ExampleIP_IsPrivate() {
262 ipv6Private := net.ParseIP("fc00::")
263 ipv6Public := net.ParseIP("fe00::")
264 ipv4Private := net.ParseIP("10.255.0.0")
265 ipv4Public := net.ParseIP("11.0.0.0")
267 fmt.Println(ipv6Private.IsPrivate())
268 fmt.Println(ipv6Public.IsPrivate())
269 fmt.Println(ipv4Private.IsPrivate())
270 fmt.Println(ipv4Public.IsPrivate())
279 func ExampleIP_IsUnspecified() {
280 ipv6Unspecified := net.ParseIP("::")
281 ipv6Specified := net.ParseIP("fe00::")
282 ipv4Unspecified := net.ParseIP("0.0.0.0")
283 ipv4Specified := net.ParseIP("8.8.8.8")
285 fmt.Println(ipv6Unspecified.IsUnspecified())
286 fmt.Println(ipv6Specified.IsUnspecified())
287 fmt.Println(ipv4Unspecified.IsUnspecified())
288 fmt.Println(ipv4Specified.IsUnspecified())
297 func ExampleIP_Mask() {
298 ipv4Addr := net.ParseIP("192.0.2.1")
299 // This mask corresponds to a /24 subnet for IPv4.
300 ipv4Mask := net.CIDRMask(24, 32)
301 fmt.Println(ipv4Addr.Mask(ipv4Mask))
303 ipv6Addr := net.ParseIP("2001:db8:a0b:12f0::1")
304 // This mask corresponds to a /32 subnet for IPv6.
305 ipv6Mask := net.CIDRMask(32, 128)
306 fmt.Println(ipv6Addr.Mask(ipv6Mask))
313 func ExampleIP_String() {
314 ipv6 := net.IP{0xfc, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}
315 ipv4 := net.IPv4(10, 255, 0, 0)
317 fmt.Println(ipv6.String())
318 fmt.Println(ipv4.String())
325 func ExampleIP_To16() {
326 ipv6 := net.IP{0xfc, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}
327 ipv4 := net.IPv4(10, 255, 0, 0)
329 fmt.Println(ipv6.To16())
330 fmt.Println(ipv4.To16())
337 func ExampleIP_to4() {
338 ipv6 := net.IP{0xfc, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}
339 ipv4 := net.IPv4(10, 255, 0, 0)
341 fmt.Println(ipv6.To4())
342 fmt.Println(ipv4.To4())
349 func ExampleCIDRMask() {
350 // This mask corresponds to a /31 subnet for IPv4.
351 fmt.Println(net.CIDRMask(31, 32))
353 // This mask corresponds to a /64 subnet for IPv6.
354 fmt.Println(net.CIDRMask(64, 128))
358 // ffffffffffffffff0000000000000000
361 func ExampleIPv4Mask() {
362 fmt.Println(net.IPv4Mask(255, 255, 255, 0))
368 func ExampleUDPConn_WriteTo() {
369 // Unlike Dial, ListenPacket creates a connection without any
370 // association with peers.
371 conn, err := net.ListenPacket("udp", ":0")
377 dst, err := net.ResolveUDPAddr("udp", "192.0.2.1:2000")
382 // The connection can write data to the desired address.
383 _, err = conn.WriteTo([]byte("data"), dst)