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Source file src/net/iprawsock_posix.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	// +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	}
   228	

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