github.com/roboticscm/goman@v0.0.0-20210203095141-87c07b4a0a55/src/net/iprawsock_posix.go (about)

     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  // +build darwin dragonfly freebsd linux nacl netbsd openbsd solaris windows
     6  
     7  package net
     8  
     9  import (
    10  	"syscall"
    11  	"time"
    12  )
    13  
    14  // BUG(mikio): On every POSIX platform, reads from the "ip4" network
    15  // using the ReadFrom or ReadFromIP method might not return a complete
    16  // IPv4 packet, including its header, even if there is space
    17  // available. This can occur even in cases where Read or ReadMsgIP
    18  // could return a complete packet. For this reason, it is recommended
    19  // that you do not uses these methods if it is important to receive a
    20  // full packet.
    21  //
    22  // The Go 1 compatibility guidelines make it impossible for us to
    23  // change the behavior of these methods; use Read or ReadMsgIP
    24  // instead.
    25  
    26  func sockaddrToIP(sa syscall.Sockaddr) Addr {
    27  	switch sa := sa.(type) {
    28  	case *syscall.SockaddrInet4:
    29  		return &IPAddr{IP: sa.Addr[0:]}
    30  	case *syscall.SockaddrInet6:
    31  		return &IPAddr{IP: sa.Addr[0:], Zone: zoneToString(int(sa.ZoneId))}
    32  	}
    33  	return nil
    34  }
    35  
    36  func (a *IPAddr) family() int {
    37  	if a == nil || len(a.IP) <= IPv4len {
    38  		return syscall.AF_INET
    39  	}
    40  	if a.IP.To4() != nil {
    41  		return syscall.AF_INET
    42  	}
    43  	return syscall.AF_INET6
    44  }
    45  
    46  func (a *IPAddr) isWildcard() bool {
    47  	if a == nil || a.IP == nil {
    48  		return true
    49  	}
    50  	return a.IP.IsUnspecified()
    51  }
    52  
    53  func (a *IPAddr) sockaddr(family int) (syscall.Sockaddr, error) {
    54  	if a == nil {
    55  		return nil, nil
    56  	}
    57  	return ipToSockaddr(family, a.IP, 0, a.Zone)
    58  }
    59  
    60  // IPConn is the implementation of the Conn and PacketConn interfaces
    61  // for IP network connections.
    62  type IPConn struct {
    63  	conn
    64  }
    65  
    66  func newIPConn(fd *netFD) *IPConn { return &IPConn{conn{fd}} }
    67  
    68  // ReadFromIP reads an IP packet from c, copying the payload into b.
    69  // It returns the number of bytes copied into b and the return address
    70  // that was on the packet.
    71  //
    72  // ReadFromIP can be made to time out and return an error with
    73  // Timeout() == true after a fixed time limit; see SetDeadline and
    74  // SetReadDeadline.
    75  func (c *IPConn) ReadFromIP(b []byte) (int, *IPAddr, error) {
    76  	if !c.ok() {
    77  		return 0, nil, syscall.EINVAL
    78  	}
    79  	// TODO(cw,rsc): consider using readv if we know the family
    80  	// type to avoid the header trim/copy
    81  	var addr *IPAddr
    82  	n, sa, err := c.fd.readFrom(b)
    83  	switch sa := sa.(type) {
    84  	case *syscall.SockaddrInet4:
    85  		addr = &IPAddr{IP: sa.Addr[0:]}
    86  		if len(b) >= IPv4len { // discard ipv4 header
    87  			hsize := (int(b[0]) & 0xf) * 4
    88  			copy(b, b[hsize:])
    89  			n -= hsize
    90  		}
    91  	case *syscall.SockaddrInet6:
    92  		addr = &IPAddr{IP: sa.Addr[0:], Zone: zoneToString(int(sa.ZoneId))}
    93  	}
    94  	return n, addr, err
    95  }
    96  
    97  // ReadFrom implements the PacketConn ReadFrom method.
    98  func (c *IPConn) ReadFrom(b []byte) (int, Addr, error) {
    99  	if !c.ok() {
   100  		return 0, nil, syscall.EINVAL
   101  	}
   102  	n, addr, err := c.ReadFromIP(b)
   103  	return n, addr.toAddr(), err
   104  }
   105  
   106  // ReadMsgIP reads a packet from c, copying the payload into b and the
   107  // associated out-of-band data into oob.  It returns the number of
   108  // bytes copied into b, the number of bytes copied into oob, the flags
   109  // that were set on the packet and the source address of the packet.
   110  func (c *IPConn) ReadMsgIP(b, oob []byte) (n, oobn, flags int, addr *IPAddr, err error) {
   111  	if !c.ok() {
   112  		return 0, 0, 0, nil, syscall.EINVAL
   113  	}
   114  	var sa syscall.Sockaddr
   115  	n, oobn, flags, sa, err = c.fd.readMsg(b, oob)
   116  	switch sa := sa.(type) {
   117  	case *syscall.SockaddrInet4:
   118  		addr = &IPAddr{IP: sa.Addr[0:]}
   119  	case *syscall.SockaddrInet6:
   120  		addr = &IPAddr{IP: sa.Addr[0:], Zone: zoneToString(int(sa.ZoneId))}
   121  	}
   122  	return
   123  }
   124  
   125  // WriteToIP writes an IP packet to addr via c, copying the payload
   126  // from b.
   127  //
   128  // WriteToIP can be made to time out and return an error with
   129  // Timeout() == true after a fixed time limit; see SetDeadline and
   130  // SetWriteDeadline.  On packet-oriented connections, write timeouts
   131  // are rare.
   132  func (c *IPConn) WriteToIP(b []byte, addr *IPAddr) (int, error) {
   133  	if !c.ok() {
   134  		return 0, syscall.EINVAL
   135  	}
   136  	if c.fd.isConnected {
   137  		return 0, &OpError{Op: "write", Net: c.fd.net, Addr: addr, Err: ErrWriteToConnected}
   138  	}
   139  	if addr == nil {
   140  		return 0, &OpError{Op: "write", Net: c.fd.net, Addr: nil, Err: errMissingAddress}
   141  	}
   142  	sa, err := addr.sockaddr(c.fd.family)
   143  	if err != nil {
   144  		return 0, &OpError{"write", c.fd.net, addr, err}
   145  	}
   146  	return c.fd.writeTo(b, sa)
   147  }
   148  
   149  // WriteTo implements the PacketConn WriteTo method.
   150  func (c *IPConn) WriteTo(b []byte, addr Addr) (int, error) {
   151  	if !c.ok() {
   152  		return 0, syscall.EINVAL
   153  	}
   154  	a, ok := addr.(*IPAddr)
   155  	if !ok {
   156  		return 0, &OpError{"write", c.fd.net, addr, syscall.EINVAL}
   157  	}
   158  	return c.WriteToIP(b, a)
   159  }
   160  
   161  // WriteMsgIP writes a packet to addr via c, copying the payload from
   162  // b and the associated out-of-band data from oob.  It returns the
   163  // number of payload and out-of-band bytes written.
   164  func (c *IPConn) WriteMsgIP(b, oob []byte, addr *IPAddr) (n, oobn int, err error) {
   165  	if !c.ok() {
   166  		return 0, 0, syscall.EINVAL
   167  	}
   168  	if c.fd.isConnected {
   169  		return 0, 0, &OpError{Op: "write", Net: c.fd.net, Addr: addr, Err: ErrWriteToConnected}
   170  	}
   171  	if addr == nil {
   172  		return 0, 0, &OpError{Op: "write", Net: c.fd.net, Addr: nil, Err: errMissingAddress}
   173  	}
   174  	sa, err := addr.sockaddr(c.fd.family)
   175  	if err != nil {
   176  		return 0, 0, &OpError{"write", c.fd.net, addr, err}
   177  	}
   178  	return c.fd.writeMsg(b, oob, sa)
   179  }
   180  
   181  // DialIP connects to the remote address raddr on the network protocol
   182  // netProto, which must be "ip", "ip4", or "ip6" followed by a colon
   183  // and a protocol number or name.
   184  func DialIP(netProto string, laddr, raddr *IPAddr) (*IPConn, error) {
   185  	return dialIP(netProto, laddr, raddr, noDeadline)
   186  }
   187  
   188  func dialIP(netProto string, laddr, raddr *IPAddr, deadline time.Time) (*IPConn, error) {
   189  	net, proto, err := parseNetwork(netProto)
   190  	if err != nil {
   191  		return nil, &OpError{Op: "dial", Net: netProto, Addr: raddr, Err: err}
   192  	}
   193  	switch net {
   194  	case "ip", "ip4", "ip6":
   195  	default:
   196  		return nil, &OpError{Op: "dial", Net: netProto, Addr: raddr, Err: UnknownNetworkError(netProto)}
   197  	}
   198  	if raddr == nil {
   199  		return nil, &OpError{Op: "dial", Net: netProto, Addr: nil, Err: errMissingAddress}
   200  	}
   201  	fd, err := internetSocket(net, laddr, raddr, deadline, syscall.SOCK_RAW, proto, "dial")
   202  	if err != nil {
   203  		return nil, &OpError{Op: "dial", Net: netProto, Addr: raddr, Err: err}
   204  	}
   205  	return newIPConn(fd), nil
   206  }
   207  
   208  // ListenIP listens for incoming IP packets addressed to the local
   209  // address laddr.  The returned connection's ReadFrom and WriteTo
   210  // methods can be used to receive and send IP packets with per-packet
   211  // addressing.
   212  func ListenIP(netProto string, laddr *IPAddr) (*IPConn, error) {
   213  	net, proto, err := parseNetwork(netProto)
   214  	if err != nil {
   215  		return nil, &OpError{Op: "dial", Net: netProto, Addr: laddr, Err: err}
   216  	}
   217  	switch net {
   218  	case "ip", "ip4", "ip6":
   219  	default:
   220  		return nil, &OpError{Op: "listen", Net: netProto, Addr: laddr, Err: UnknownNetworkError(netProto)}
   221  	}
   222  	fd, err := internetSocket(net, laddr, nil, noDeadline, syscall.SOCK_RAW, proto, "listen")
   223  	if err != nil {
   224  		return nil, &OpError{Op: "listen", Net: netProto, Addr: laddr, Err: err}
   225  	}
   226  	return newIPConn(fd), nil
   227  }