github.com/graybobo/golang.org-package-offline-cache@v0.0.0-20200626051047-6608995c132f/x/net/ipv6/payload_cmsg.go (about)

     1  // Copyright 2013 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 !nacl,!plan9,!windows
     6  
     7  package ipv6
     8  
     9  import (
    10  	"net"
    11  	"syscall"
    12  )
    13  
    14  // ReadFrom reads a payload of the received IPv6 datagram, from the
    15  // endpoint c, copying the payload into b.  It returns the number of
    16  // bytes copied into b, the control message cm and the source address
    17  // src of the received datagram.
    18  func (c *payloadHandler) ReadFrom(b []byte) (n int, cm *ControlMessage, src net.Addr, err error) {
    19  	if !c.ok() {
    20  		return 0, nil, nil, syscall.EINVAL
    21  	}
    22  	oob := newControlMessage(&c.rawOpt)
    23  	var oobn int
    24  	switch c := c.PacketConn.(type) {
    25  	case *net.UDPConn:
    26  		if n, oobn, _, src, err = c.ReadMsgUDP(b, oob); err != nil {
    27  			return 0, nil, nil, err
    28  		}
    29  	case *net.IPConn:
    30  		if n, oobn, _, src, err = c.ReadMsgIP(b, oob); err != nil {
    31  			return 0, nil, nil, err
    32  		}
    33  	default:
    34  		return 0, nil, nil, errInvalidConnType
    35  	}
    36  	if cm, err = parseControlMessage(oob[:oobn]); err != nil {
    37  		return 0, nil, nil, err
    38  	}
    39  	if cm != nil {
    40  		cm.Src = netAddrToIP16(src)
    41  	}
    42  	return
    43  }
    44  
    45  // WriteTo writes a payload of the IPv6 datagram, to the destination
    46  // address dst through the endpoint c, copying the payload from b.  It
    47  // returns the number of bytes written.  The control message cm allows
    48  // the IPv6 header fields and the datagram path to be specified.  The
    49  // cm may be nil if control of the outgoing datagram is not required.
    50  func (c *payloadHandler) WriteTo(b []byte, cm *ControlMessage, dst net.Addr) (n int, err error) {
    51  	if !c.ok() {
    52  		return 0, syscall.EINVAL
    53  	}
    54  	oob := marshalControlMessage(cm)
    55  	if dst == nil {
    56  		return 0, errMissingAddress
    57  	}
    58  	switch c := c.PacketConn.(type) {
    59  	case *net.UDPConn:
    60  		n, _, err = c.WriteMsgUDP(b, oob, dst.(*net.UDPAddr))
    61  	case *net.IPConn:
    62  		n, _, err = c.WriteMsgIP(b, oob, dst.(*net.IPAddr))
    63  	default:
    64  		return 0, errInvalidConnType
    65  	}
    66  	if err != nil {
    67  		return 0, err
    68  	}
    69  	return
    70  }