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 5 package net 6 7 import ( 8 "context" 9 "io" 10 "os" 11 "syscall" 12 "time" 13 ) 14 15 // BUG(mikio): On Windows, the File method of TCPListener is not 16 // implemented. 17 18 // TCPAddr represents the address of a TCP end point. 19 type TCPAddr struct { 20 IP IP 21 Port int 22 Zone string // IPv6 scoped addressing zone 23 } 24 25 // Network returns the address's network name, "tcp". 26 func (a *TCPAddr) Network() string { return "tcp" } 27 28 func (a *TCPAddr) String() string { 29 if a == nil { 30 return "<nil>" 31 } 32 ip := ipEmptyString(a.IP) 33 if a.Zone != "" { 34 return JoinHostPort(ip+"%"+a.Zone, itoa(a.Port)) 35 } 36 return JoinHostPort(ip, itoa(a.Port)) 37 } 38 39 func (a *TCPAddr) isWildcard() bool { 40 if a == nil || a.IP == nil { 41 return true 42 } 43 return a.IP.IsUnspecified() 44 } 45 46 func (a *TCPAddr) opAddr() Addr { 47 if a == nil { 48 return nil 49 } 50 return a 51 } 52 53 // ResolveTCPAddr parses addr as a TCP address of the form "host:port" 54 // or "[ipv6-host%zone]:port" and resolves a pair of domain name and 55 // port name on the network net, which must be "tcp", "tcp4" or 56 // "tcp6". A literal address or host name for IPv6 must be enclosed 57 // in square brackets, as in "[::1]:80", "[ipv6-host]:http" or 58 // "[ipv6-host%zone]:80". 59 // 60 // Resolving a hostname is not recommended because this returns at most 61 // one of its IP addresses. 62 func ResolveTCPAddr(net, addr string) (*TCPAddr, error) { 63 switch net { 64 case "tcp", "tcp4", "tcp6": 65 case "": // a hint wildcard for Go 1.0 undocumented behavior 66 net = "tcp" 67 default: 68 return nil, UnknownNetworkError(net) 69 } 70 addrs, err := DefaultResolver.internetAddrList(context.Background(), net, addr) 71 if err != nil { 72 return nil, err 73 } 74 return addrs.first(isIPv4).(*TCPAddr), nil 75 } 76 77 // TCPConn is an implementation of the Conn interface for TCP network 78 // connections. 79 type TCPConn struct { 80 conn 81 } 82 83 // ReadFrom implements the io.ReaderFrom ReadFrom method. 84 func (c *TCPConn) ReadFrom(r io.Reader) (int64, error) { 85 if !c.ok() { 86 return 0, syscall.EINVAL 87 } 88 n, err := c.readFrom(r) 89 if err != nil && err != io.EOF { 90 err = &OpError{Op: "readfrom", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err} 91 } 92 return n, err 93 } 94 95 // CloseRead shuts down the reading side of the TCP connection. 96 // Most callers should just use Close. 97 func (c *TCPConn) CloseRead() error { 98 if !c.ok() { 99 return syscall.EINVAL 100 } 101 if err := c.fd.closeRead(); err != nil { 102 return &OpError{Op: "close", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err} 103 } 104 return nil 105 } 106 107 // CloseWrite shuts down the writing side of the TCP connection. 108 // Most callers should just use Close. 109 func (c *TCPConn) CloseWrite() error { 110 if !c.ok() { 111 return syscall.EINVAL 112 } 113 if err := c.fd.closeWrite(); err != nil { 114 return &OpError{Op: "close", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err} 115 } 116 return nil 117 } 118 119 // SetLinger sets the behavior of Close on a connection which still 120 // has data waiting to be sent or to be acknowledged. 121 // 122 // If sec < 0 (the default), the operating system finishes sending the 123 // data in the background. 124 // 125 // If sec == 0, the operating system discards any unsent or 126 // unacknowledged data. 127 // 128 // If sec > 0, the data is sent in the background as with sec < 0. On 129 // some operating systems after sec seconds have elapsed any remaining 130 // unsent data may be discarded. 131 func (c *TCPConn) SetLinger(sec int) error { 132 if !c.ok() { 133 return syscall.EINVAL 134 } 135 if err := setLinger(c.fd, sec); err != nil { 136 return &OpError{Op: "set", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err} 137 } 138 return nil 139 } 140 141 // SetKeepAlive sets whether the operating system should send 142 // keepalive messages on the connection. 143 func (c *TCPConn) SetKeepAlive(keepalive bool) error { 144 if !c.ok() { 145 return syscall.EINVAL 146 } 147 if err := setKeepAlive(c.fd, keepalive); err != nil { 148 return &OpError{Op: "set", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err} 149 } 150 return nil 151 } 152 153 // SetKeepAlivePeriod sets period between keep alives. 154 func (c *TCPConn) SetKeepAlivePeriod(d time.Duration) error { 155 if !c.ok() { 156 return syscall.EINVAL 157 } 158 if err := setKeepAlivePeriod(c.fd, d); err != nil { 159 return &OpError{Op: "set", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err} 160 } 161 return nil 162 } 163 164 // SetNoDelay controls whether the operating system should delay 165 // packet transmission in hopes of sending fewer packets (Nagle's 166 // algorithm). The default is true (no delay), meaning that data is 167 // sent as soon as possible after a Write. 168 func (c *TCPConn) SetNoDelay(noDelay bool) error { 169 if !c.ok() { 170 return syscall.EINVAL 171 } 172 if err := setNoDelay(c.fd, noDelay); err != nil { 173 return &OpError{Op: "set", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err} 174 } 175 return nil 176 } 177 178 func newTCPConn(fd *netFD) *TCPConn { 179 c := &TCPConn{conn{fd}} 180 setNoDelay(c.fd, true) 181 return c 182 } 183 184 // DialTCP connects to the remote address raddr on the network net, 185 // which must be "tcp", "tcp4", or "tcp6". If laddr is not nil, it is 186 // used as the local address for the connection. 187 func DialTCP(net string, laddr, raddr *TCPAddr) (*TCPConn, error) { 188 switch net { 189 case "tcp", "tcp4", "tcp6": 190 default: 191 return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: UnknownNetworkError(net)} 192 } 193 if raddr == nil { 194 return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: nil, Err: errMissingAddress} 195 } 196 c, err := dialTCP(context.Background(), net, laddr, raddr) 197 if err != nil { 198 return nil, &OpError{Op: "dial", Net: net, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: err} 199 } 200 return c, nil 201 } 202 203 // TCPListener is a TCP network listener. Clients should typically 204 // use variables of type Listener instead of assuming TCP. 205 type TCPListener struct { 206 fd *netFD 207 } 208 209 // AcceptTCP accepts the next incoming call and returns the new 210 // connection. 211 func (l *TCPListener) AcceptTCP() (*TCPConn, error) { 212 if !l.ok() { 213 return nil, syscall.EINVAL 214 } 215 c, err := l.accept() 216 if err != nil { 217 return nil, &OpError{Op: "accept", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err} 218 } 219 return c, nil 220 } 221 222 // Accept implements the Accept method in the Listener interface; it 223 // waits for the next call and returns a generic Conn. 224 func (l *TCPListener) Accept() (Conn, error) { 225 if !l.ok() { 226 return nil, syscall.EINVAL 227 } 228 c, err := l.accept() 229 if err != nil { 230 return nil, &OpError{Op: "accept", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err} 231 } 232 return c, nil 233 } 234 235 // Close stops listening on the TCP address. 236 // Already Accepted connections are not closed. 237 func (l *TCPListener) Close() error { 238 if !l.ok() { 239 return syscall.EINVAL 240 } 241 if err := l.close(); err != nil { 242 return &OpError{Op: "close", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err} 243 } 244 return nil 245 } 246 247 // Addr returns the listener's network address, a *TCPAddr. 248 // The Addr returned is shared by all invocations of Addr, so 249 // do not modify it. 250 func (l *TCPListener) Addr() Addr { return l.fd.laddr } 251 252 // SetDeadline sets the deadline associated with the listener. 253 // A zero time value disables the deadline. 254 func (l *TCPListener) SetDeadline(t time.Time) error { 255 if !l.ok() { 256 return syscall.EINVAL 257 } 258 if err := l.fd.setDeadline(t); err != nil { 259 return &OpError{Op: "set", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err} 260 } 261 return nil 262 } 263 264 // File returns a copy of the underlying os.File, set to blocking 265 // mode. It is the caller's responsibility to close f when finished. 266 // Closing l does not affect f, and closing f does not affect l. 267 // 268 // The returned os.File's file descriptor is different from the 269 // connection's. Attempting to change properties of the original 270 // using this duplicate may or may not have the desired effect. 271 func (l *TCPListener) File() (f *os.File, err error) { 272 if !l.ok() { 273 return nil, syscall.EINVAL 274 } 275 f, err = l.file() 276 if err != nil { 277 return nil, &OpError{Op: "file", Net: l.fd.net, Source: nil, Addr: l.fd.laddr, Err: err} 278 } 279 return 280 } 281 282 // ListenTCP announces on the TCP address laddr and returns a TCP 283 // listener. Net must be "tcp", "tcp4", or "tcp6". If laddr has a 284 // port of 0, ListenTCP will choose an available port. The caller can 285 // use the Addr method of TCPListener to retrieve the chosen address. 286 func ListenTCP(net string, laddr *TCPAddr) (*TCPListener, error) { 287 switch net { 288 case "tcp", "tcp4", "tcp6": 289 default: 290 return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: laddr.opAddr(), Err: UnknownNetworkError(net)} 291 } 292 if laddr == nil { 293 laddr = &TCPAddr{} 294 } 295 ln, err := listenTCP(context.Background(), net, laddr) 296 if err != nil { 297 return nil, &OpError{Op: "listen", Net: net, Source: nil, Addr: laddr.opAddr(), Err: err} 298 } 299 return ln, nil 300 } 301