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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) sockaddr(family int) (syscall.Sockaddr, error) {
    47		if a == nil {
    48			return nil, nil
    49		}
    50		return ipToSockaddr(family, a.IP, 0, a.Zone)
    51	}
    52	
    53	// IPConn is the implementation of the Conn and PacketConn interfaces
    54	// for IP network connections.
    55	type IPConn struct {
    56		conn
    57	}
    58	
    59	func newIPConn(fd *netFD) *IPConn { return &IPConn{conn{fd}} }
    60	
    61	// ReadFromIP reads an IP packet from c, copying the payload into b.
    62	// It returns the number of bytes copied into b and the return address
    63	// that was on the packet.
    64	//
    65	// ReadFromIP can be made to time out and return an error with
    66	// Timeout() == true after a fixed time limit; see SetDeadline and
    67	// SetReadDeadline.
    68	func (c *IPConn) ReadFromIP(b []byte) (int, *IPAddr, error) {
    69		if !c.ok() {
    70			return 0, nil, syscall.EINVAL
    71		}
    72		// TODO(cw,rsc): consider using readv if we know the family
    73		// type to avoid the header trim/copy
    74		var addr *IPAddr
    75		n, sa, err := c.fd.readFrom(b)
    76		switch sa := sa.(type) {
    77		case *syscall.SockaddrInet4:
    78			addr = &IPAddr{IP: sa.Addr[0:]}
    79			n = stripIPv4Header(n, b)
    80		case *syscall.SockaddrInet6:
    81			addr = &IPAddr{IP: sa.Addr[0:], Zone: zoneToString(int(sa.ZoneId))}
    82		}
    83		if err != nil {
    84			err = &OpError{Op: "read", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
    85		}
    86		return n, addr, err
    87	}
    88	
    89	func stripIPv4Header(n int, b []byte) int {
    90		if len(b) < 20 {
    91			return n
    92		}
    93		l := int(b[0]&0x0f) << 2
    94		if 20 > l || l > len(b) {
    95			return n
    96		}
    97		if b[0]>>4 != 4 {
    98			return n
    99		}
   100		copy(b, b[l:])
   101		return n - l
   102	}
   103	
   104	// ReadFrom implements the PacketConn ReadFrom method.
   105	func (c *IPConn) ReadFrom(b []byte) (int, Addr, error) {
   106		if !c.ok() {
   107			return 0, nil, syscall.EINVAL
   108		}
   109		n, addr, err := c.ReadFromIP(b)
   110		if addr == nil {
   111			return n, nil, err
   112		}
   113		return n, addr, err
   114	}
   115	
   116	// ReadMsgIP reads a packet from c, copying the payload into b and the
   117	// associated out-of-band data into oob.  It returns the number of
   118	// bytes copied into b, the number of bytes copied into oob, the flags
   119	// that were set on the packet and the source address of the packet.
   120	func (c *IPConn) ReadMsgIP(b, oob []byte) (n, oobn, flags int, addr *IPAddr, err error) {
   121		if !c.ok() {
   122			return 0, 0, 0, nil, syscall.EINVAL
   123		}
   124		var sa syscall.Sockaddr
   125		n, oobn, flags, sa, err = c.fd.readMsg(b, oob)
   126		switch sa := sa.(type) {
   127		case *syscall.SockaddrInet4:
   128			addr = &IPAddr{IP: sa.Addr[0:]}
   129		case *syscall.SockaddrInet6:
   130			addr = &IPAddr{IP: sa.Addr[0:], Zone: zoneToString(int(sa.ZoneId))}
   131		}
   132		if err != nil {
   133			err = &OpError{Op: "read", Net: c.fd.net, Source: c.fd.laddr, Addr: c.fd.raddr, Err: err}
   134		}
   135		return
   136	}
   137	
   138	// WriteToIP writes an IP packet to addr via c, copying the payload
   139	// from b.
   140	//
   141	// WriteToIP can be made to time out and return an error with
   142	// Timeout() == true after a fixed time limit; see SetDeadline and
   143	// SetWriteDeadline.  On packet-oriented connections, write timeouts
   144	// are rare.
   145	func (c *IPConn) WriteToIP(b []byte, addr *IPAddr) (int, error) {
   146		if !c.ok() {
   147			return 0, syscall.EINVAL
   148		}
   149		if c.fd.isConnected {
   150			return 0, &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr.opAddr(), Err: ErrWriteToConnected}
   151		}
   152		if addr == nil {
   153			return 0, &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: nil, Err: errMissingAddress}
   154		}
   155		sa, err := addr.sockaddr(c.fd.family)
   156		if err != nil {
   157			return 0, &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr.opAddr(), Err: err}
   158		}
   159		n, err := c.fd.writeTo(b, sa)
   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		return c.WriteToIP(b, a)
   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		if c.fd.isConnected {
   186			return 0, 0, &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr.opAddr(), Err: ErrWriteToConnected}
   187		}
   188		if addr == nil {
   189			return 0, 0, &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: nil, Err: errMissingAddress}
   190		}
   191		var sa syscall.Sockaddr
   192		sa, err = addr.sockaddr(c.fd.family)
   193		if err != nil {
   194			return 0, 0, &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr.opAddr(), Err: err}
   195		}
   196		n, oobn, err = c.fd.writeMsg(b, oob, sa)
   197		if err != nil {
   198			err = &OpError{Op: "write", Net: c.fd.net, Source: c.fd.laddr, Addr: addr.opAddr(), Err: err}
   199		}
   200		return
   201	}
   202	
   203	// DialIP connects to the remote address raddr on the network protocol
   204	// netProto, which must be "ip", "ip4", or "ip6" followed by a colon
   205	// and a protocol number or name.
   206	func DialIP(netProto string, laddr, raddr *IPAddr) (*IPConn, error) {
   207		return dialIP(netProto, laddr, raddr, noDeadline)
   208	}
   209	
   210	func dialIP(netProto string, laddr, raddr *IPAddr, deadline time.Time) (*IPConn, error) {
   211		net, proto, err := parseNetwork(netProto)
   212		if err != nil {
   213			return nil, &OpError{Op: "dial", Net: netProto, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: err}
   214		}
   215		switch net {
   216		case "ip", "ip4", "ip6":
   217		default:
   218			return nil, &OpError{Op: "dial", Net: netProto, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: UnknownNetworkError(netProto)}
   219		}
   220		if raddr == nil {
   221			return nil, &OpError{Op: "dial", Net: netProto, Source: laddr.opAddr(), Addr: nil, Err: errMissingAddress}
   222		}
   223		fd, err := internetSocket(net, laddr, raddr, deadline, syscall.SOCK_RAW, proto, "dial")
   224		if err != nil {
   225			return nil, &OpError{Op: "dial", Net: netProto, Source: laddr.opAddr(), Addr: raddr.opAddr(), Err: err}
   226		}
   227		return newIPConn(fd), nil
   228	}
   229	
   230	// ListenIP listens for incoming IP packets addressed to the local
   231	// address laddr.  The returned connection's ReadFrom and WriteTo
   232	// methods can be used to receive and send IP packets with per-packet
   233	// addressing.
   234	func ListenIP(netProto string, laddr *IPAddr) (*IPConn, error) {
   235		net, proto, err := parseNetwork(netProto)
   236		if err != nil {
   237			return nil, &OpError{Op: "listen", Net: netProto, Source: nil, Addr: laddr.opAddr(), Err: err}
   238		}
   239		switch net {
   240		case "ip", "ip4", "ip6":
   241		default:
   242			return nil, &OpError{Op: "listen", Net: netProto, Source: nil, Addr: laddr.opAddr(), Err: UnknownNetworkError(netProto)}
   243		}
   244		fd, err := internetSocket(net, laddr, nil, noDeadline, syscall.SOCK_RAW, proto, "listen")
   245		if err != nil {
   246			return nil, &OpError{Op: "listen", Net: netProto, Source: nil, Addr: laddr.opAddr(), Err: err}
   247		}
   248		return newIPConn(fd), nil
   249	}
   250	

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