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Source file src/net/iprawsock.go

     1	// Copyright 2010 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		"syscall"
    10	)
    11	
    12	// BUG(mikio): On every POSIX platform, reads from the "ip4" network
    13	// using the ReadFrom or ReadFromIP method might not return a complete
    14	// IPv4 packet, including its header, even if there is space
    15	// available. This can occur even in cases where Read or ReadMsgIP
    16	// could return a complete packet. For this reason, it is recommended
    17	// that you do not use these methods if it is important to receive a
    18	// full packet.
    19	//
    20	// The Go 1 compatibility guidelines make it impossible for us to
    21	// change the behavior of these methods; use Read or ReadMsgIP
    22	// instead.
    23	
    24	// BUG(mikio): On NaCl, Plan 9 and Windows, the ReadMsgIP and
    25	// WriteMsgIP methods of IPConn are not implemented.
    26	
    27	// BUG(mikio): On Windows, the File method of IPConn is not
    28	// implemented.
    29	
    30	// IPAddr represents the address of an IP end point.
    31	type IPAddr struct {
    32		IP   IP
    33		Zone string // IPv6 scoped addressing zone
    34	}
    35	
    36	// Network returns the address's network name, "ip".
    37	func (a *IPAddr) Network() string { return "ip" }
    38	
    39	func (a *IPAddr) String() string {
    40		if a == nil {
    41			return "<nil>"
    42		}
    43		ip := ipEmptyString(a.IP)
    44		if a.Zone != "" {
    45			return ip + "%" + a.Zone
    46		}
    47		return ip
    48	}
    49	
    50	func (a *IPAddr) isWildcard() bool {
    51		if a == nil || a.IP == nil {
    52			return true
    53		}
    54		return a.IP.IsUnspecified()
    55	}
    56	
    57	func (a *IPAddr) opAddr() Addr {
    58		if a == nil {
    59			return nil
    60		}
    61		return a
    62	}
    63	
    64	// ResolveIPAddr parses addr as an IP address of the form "host" or
    65	// "ipv6-host%zone" and resolves the domain name on the network net,
    66	// which must be "ip", "ip4" or "ip6".
    67	//
    68	// Resolving a hostname is not recommended because this returns at most
    69	// one of its IP addresses.
    70	func ResolveIPAddr(net, addr string) (*IPAddr, error) {
    71		if net == "" { // a hint wildcard for Go 1.0 undocumented behavior
    72			net = "ip"
    73		}
    74		afnet, _, err := parseNetwork(context.Background(), net)
    75		if err != nil {
    76			return nil, err
    77		}
    78		switch afnet {
    79		case "ip", "ip4", "ip6":
    80		default:
    81			return nil, UnknownNetworkError(net)
    82		}
    83		addrs, err := DefaultResolver.internetAddrList(context.Background(), afnet, addr)
    84		if err != nil {
    85			return nil, err
    86		}
    87		return addrs.first(isIPv4).(*IPAddr), nil
    88	}
    89	
    90	// IPConn is the implementation of the Conn and PacketConn interfaces
    91	// for IP network connections.
    92	type IPConn struct {
    93		conn
    94	}
    95	
    96	// ReadFromIP reads an IP packet from c, copying the payload into b.
    97	// It returns the number of bytes copied into b and the return address
    98	// that was on the packet.
    99	//
   100	// ReadFromIP can be made to time out and return an error with
   101	// Timeout() == true after a fixed time limit; see SetDeadline and
   102	// SetReadDeadline.
   103	func (c *IPConn) ReadFromIP(b []byte) (int, *IPAddr, error) {
   104		if !c.ok() {
   105			return 0, nil, syscall.EINVAL
   106		}
   107		n, addr, err := c.readFrom(b)
   108		if err != nil {
   109			err = &OpError{Op: "read", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
   110		}
   111		return n, addr, err
   112	}
   113	
   114	// ReadFrom implements the PacketConn ReadFrom method.
   115	func (c *IPConn) ReadFrom(b []byte) (int, Addr, error) {
   116		if !c.ok() {
   117			return 0, nil, syscall.EINVAL
   118		}
   119		n, addr, err := c.readFrom(b)
   120		if err != nil {
   121			err = &OpError{Op: "read", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
   122		}
   123		if addr == nil {
   124			return n, nil, err
   125		}
   126		return n, addr, err
   127	}
   128	
   129	// ReadMsgIP reads a packet from c, copying the payload into b and the
   130	// associated out-of-band data into oob. It returns the number of
   131	// bytes copied into b, the number of bytes copied into oob, the flags
   132	// that were set on the packet and the source address of the packet.
   133	func (c *IPConn) ReadMsgIP(b, oob []byte) (n, oobn, flags int, addr *IPAddr, err error) {
   134		if !c.ok() {
   135			return 0, 0, 0, nil, syscall.EINVAL
   136		}
   137		n, oobn, flags, addr, err = c.readMsg(b, oob)
   138		if err != nil {
   139			err = &OpError{Op: "read", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
   140		}
   141		return
   142	}
   143	
   144	// WriteToIP writes an IP packet to addr via c, copying the payload
   145	// from b.
   146	//
   147	// WriteToIP can be made to time out and return an error with
   148	// Timeout() == true after a fixed time limit; see SetDeadline and
   149	// SetWriteDeadline. On packet-oriented connections, write timeouts
   150	// are rare.
   151	func (c *IPConn) WriteToIP(b []byte, addr *IPAddr) (int, error) {
   152		if !c.ok() {
   153			return 0, syscall.EINVAL
   154		}
   155		n, err := c.writeTo(b, addr)
   156		if err != nil {
   157			err = &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr.opAddr(), Err: err}
   158		}
   159		return n, err
   160	}
   161	
   162	// WriteTo implements the PacketConn WriteTo method.
   163	func (c *IPConn) WriteTo(b []byte, addr Addr) (int, error) {
   164		if !c.ok() {
   165			return 0, syscall.EINVAL
   166		}
   167		a, ok := addr.(*IPAddr)
   168		if !ok {
   169			return 0, &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr, Err: syscall.EINVAL}
   170		}
   171		n, err := c.writeTo(b, a)
   172		if err != nil {
   173			err = &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: a.opAddr(), Err: err}
   174		}
   175		return n, err
   176	}
   177	
   178	// WriteMsgIP writes a packet to addr via c, copying the payload from
   179	// b and the associated out-of-band data from oob. It returns the
   180	// number of payload and out-of-band bytes written.
   181	func (c *IPConn) WriteMsgIP(b, oob []byte, addr *IPAddr) (n, oobn int, err error) {
   182		if !c.ok() {
   183			return 0, 0, syscall.EINVAL
   184		}
   185		n, oobn, err = c.writeMsg(b, oob, addr)
   186		if err != nil {
   187			err = &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr.opAddr(), Err: err}
   188		}
   189		return
   190	}
   191	
   192	func newIPConn(fd *netFD) *IPConn { return &IPConn{conn{fd}} }
   193	
   194	// DialIP connects to the remote address raddr on the network protocol
   195	// netProto, which must be "ip", "ip4", or "ip6" followed by a colon
   196	// and a protocol number or name.
   197	func DialIP(netProto string, laddr, raddr *IPAddr) (*IPConn, error) {
   198		c, err := dialIP(context.Background(), netProto, laddr, raddr)
   199		if err != nil {
   200			return nil, &OpError{Op: "dial", Net: netProto, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: err}
   201		}
   202		return c, nil
   203	}
   204	
   205	// ListenIP listens for incoming IP packets addressed to the local
   206	// address laddr. The returned connection's ReadFrom and WriteTo
   207	// methods can be used to receive and send IP packets with per-packet
   208	// addressing.
   209	func ListenIP(netProto string, laddr *IPAddr) (*IPConn, error) {
   210		c, err := listenIP(context.Background(), netProto, laddr)
   211		if err != nil {
   212			return nil, &OpError{Op: "listen", Net: netProto, Source: nil, Addr: laddr.opAddr(), Err: err}
   213		}
   214		return c, nil
   215	}
   216	

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