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 JS and Plan 9, methods and functions related
    25  // to IPConn are not implemented.
    26  
    27  // IPAddr represents the address of an IP end point.
    28  type IPAddr struct {
    29  	IP   IP
    30  	Zone string // IPv6 scoped addressing zone
    31  }
    32  
    33  // Network returns the address's network name, "ip".
    34  func (a *IPAddr) Network() string { return "ip" }
    35  
    36  func (a *IPAddr) String() string {
    37  	if a == nil {
    38  		return "<nil>"
    39  	}
    40  	ip := ipEmptyString(a.IP)
    41  	if a.Zone != "" {
    42  		return ip + "%" + a.Zone
    43  	}
    44  	return ip
    45  }
    46  
    47  func (a *IPAddr) isWildcard() bool {
    48  	if a == nil || a.IP == nil {
    49  		return true
    50  	}
    51  	return a.IP.IsUnspecified()
    52  }
    53  
    54  func (a *IPAddr) opAddr() Addr {
    55  	if a == nil {
    56  		return nil
    57  	}
    58  	return a
    59  }
    60  
    61  // ResolveIPAddr returns an address of IP end point.
    62  //
    63  // The network must be an IP network name.
    64  //
    65  // If the host in the address parameter is not a literal IP address,
    66  // ResolveIPAddr resolves the address to an address of IP end point.
    67  // Otherwise, it parses the address as a literal IP address.
    68  // The address parameter can use a host name, but this is not
    69  // recommended, because it will return at most one of the host name's
    70  // IP addresses.
    71  //
    72  // See func [Dial] for a description of the network and address
    73  // parameters.
    74  func ResolveIPAddr(network, address string) (*IPAddr, error) {
    75  	if network == "" { // a hint wildcard for Go 1.0 undocumented behavior
    76  		network = "ip"
    77  	}
    78  	afnet, _, err := parseNetwork(context.Background(), network, false)
    79  	if err != nil {
    80  		return nil, err
    81  	}
    82  	switch afnet {
    83  	case "ip", "ip4", "ip6":
    84  	default:
    85  		return nil, UnknownNetworkError(network)
    86  	}
    87  	addrs, err := DefaultResolver.internetAddrList(context.Background(), afnet, address)
    88  	if err != nil {
    89  		return nil, err
    90  	}
    91  	return addrs.forResolve(network, address).(*IPAddr), nil
    92  }
    93  
    94  // IPConn is the implementation of the [Conn] and [PacketConn] interfaces
    95  // for IP network connections.
    96  type IPConn struct {
    97  	conn
    98  }
    99  
   100  // SyscallConn returns a raw network connection.
   101  // This implements the [syscall.Conn] interface.
   102  func (c *IPConn) SyscallConn() (syscall.RawConn, error) {
   103  	if !c.ok() {
   104  		return nil, syscall.EINVAL
   105  	}
   106  	return newRawConn(c.fd), nil
   107  }
   108  
   109  // ReadFromIP acts like ReadFrom but returns an IPAddr.
   110  func (c *IPConn) ReadFromIP(b []byte) (int, *IPAddr, error) {
   111  	if !c.ok() {
   112  		return 0, nil, syscall.EINVAL
   113  	}
   114  	n, addr, err := c.readFrom(b)
   115  	if err != nil {
   116  		err = &OpError{Op: "read", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
   117  	}
   118  	return n, addr, err
   119  }
   120  
   121  // ReadFrom implements the [PacketConn] ReadFrom method.
   122  func (c *IPConn) ReadFrom(b []byte) (int, Addr, error) {
   123  	if !c.ok() {
   124  		return 0, nil, syscall.EINVAL
   125  	}
   126  	n, addr, err := c.readFrom(b)
   127  	if err != nil {
   128  		err = &OpError{Op: "read", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
   129  	}
   130  	if addr == nil {
   131  		return n, nil, err
   132  	}
   133  	return n, addr, err
   134  }
   135  
   136  // ReadMsgIP reads a message from c, copying the payload into b and
   137  // the associated out-of-band data into oob. It returns the number of
   138  // bytes copied into b, the number of bytes copied into oob, the flags
   139  // that were set on the message and the source address of the message.
   140  //
   141  // The packages golang.org/x/net/ipv4 and golang.org/x/net/ipv6 can be
   142  // used to manipulate IP-level socket options in oob.
   143  func (c *IPConn) ReadMsgIP(b, oob []byte) (n, oobn, flags int, addr *IPAddr, err error) {
   144  	if !c.ok() {
   145  		return 0, 0, 0, nil, syscall.EINVAL
   146  	}
   147  	n, oobn, flags, addr, err = c.readMsg(b, oob)
   148  	if err != nil {
   149  		err = &OpError{Op: "read", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
   150  	}
   151  	return
   152  }
   153  
   154  // WriteToIP acts like [IPConn.WriteTo] but takes an [IPAddr].
   155  func (c *IPConn) WriteToIP(b []byte, addr *IPAddr) (int, error) {
   156  	if !c.ok() {
   157  		return 0, syscall.EINVAL
   158  	}
   159  	n, err := c.writeTo(b, addr)
   160  	if err != nil {
   161  		err = &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr.opAddr(), Err: err}
   162  	}
   163  	return n, err
   164  }
   165  
   166  // WriteTo implements the [PacketConn] WriteTo method.
   167  func (c *IPConn) WriteTo(b []byte, addr Addr) (int, error) {
   168  	if !c.ok() {
   169  		return 0, syscall.EINVAL
   170  	}
   171  	a, ok := addr.(*IPAddr)
   172  	if !ok {
   173  		return 0, &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr, Err: syscall.EINVAL}
   174  	}
   175  	n, err := c.writeTo(b, a)
   176  	if err != nil {
   177  		err = &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: a.opAddr(), Err: err}
   178  	}
   179  	return n, err
   180  }
   181  
   182  // WriteMsgIP writes a message to addr via c, copying the payload from
   183  // b and the associated out-of-band data from oob. It returns the
   184  // number of payload and out-of-band bytes written.
   185  //
   186  // The packages golang.org/x/net/ipv4 and golang.org/x/net/ipv6 can be
   187  // used to manipulate IP-level socket options in oob.
   188  func (c *IPConn) WriteMsgIP(b, oob []byte, addr *IPAddr) (n, oobn int, err error) {
   189  	if !c.ok() {
   190  		return 0, 0, syscall.EINVAL
   191  	}
   192  	n, oobn, err = c.writeMsg(b, oob, addr)
   193  	if err != nil {
   194  		err = &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr.opAddr(), Err: err}
   195  	}
   196  	return
   197  }
   198  
   199  func newIPConn(fd *netFD) *IPConn { return &IPConn{conn{fd}} }
   200  
   201  // DialIP acts like [Dial] for IP networks.
   202  //
   203  // The network must be an IP network name; see func Dial for details.
   204  //
   205  // If laddr is nil, a local address is automatically chosen.
   206  // If the IP field of raddr is nil or an unspecified IP address, the
   207  // local system is assumed.
   208  func DialIP(network string, laddr, raddr *IPAddr) (*IPConn, error) {
   209  	if raddr == nil {
   210  		return nil, &OpError{Op: "dial", Net: network, Source: laddr.opAddr(), Addr: nil, Err: errMissingAddress}
   211  	}
   212  	sd := &sysDialer{network: network, address: raddr.String()}
   213  	c, err := sd.dialIP(context.Background(), laddr, raddr)
   214  	if err != nil {
   215  		return nil, &OpError{Op: "dial", Net: network, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: err}
   216  	}
   217  	return c, nil
   218  }
   219  
   220  // ListenIP acts like [ListenPacket] for IP networks.
   221  //
   222  // The network must be an IP network name; see func Dial for details.
   223  //
   224  // If the IP field of laddr is nil or an unspecified IP address,
   225  // ListenIP listens on all available IP addresses of the local system
   226  // except multicast IP addresses.
   227  func ListenIP(network string, laddr *IPAddr) (*IPConn, error) {
   228  	if laddr == nil {
   229  		laddr = &IPAddr{}
   230  	}
   231  	sl := &sysListener{network: network, address: laddr.String()}
   232  	c, err := sl.listenIP(context.Background(), laddr)
   233  	if err != nil {
   234  		return nil, &OpError{Op: "listen", Net: network, Source: nil, Addr: laddr.opAddr(), Err: err}
   235  	}
   236  	return c, nil
   237  }
   238
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