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Source file src/net/iprawsock_posix.go

Documentation: net

  // Copyright 2010 The Go Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style
  // license that can be found in the LICENSE file.
  
  // +build darwin dragonfly freebsd linux nacl netbsd openbsd solaris windows
  
  package net
  
  import (
  	"context"
  	"syscall"
  )
  
  func sockaddrToIP(sa syscall.Sockaddr) Addr {
  	switch sa := sa.(type) {
  	case *syscall.SockaddrInet4:
  		return &IPAddr{IP: sa.Addr[0:]}
  	case *syscall.SockaddrInet6:
  		return &IPAddr{IP: sa.Addr[0:], Zone: zoneCache.name(int(sa.ZoneId))}
  	}
  	return nil
  }
  
  func (a *IPAddr) family() int {
  	if a == nil || len(a.IP) <= IPv4len {
  		return syscall.AF_INET
  	}
  	if a.IP.To4() != nil {
  		return syscall.AF_INET
  	}
  	return syscall.AF_INET6
  }
  
  func (a *IPAddr) sockaddr(family int) (syscall.Sockaddr, error) {
  	if a == nil {
  		return nil, nil
  	}
  	return ipToSockaddr(family, a.IP, 0, a.Zone)
  }
  
  func (a *IPAddr) toLocal(net string) sockaddr {
  	return &IPAddr{loopbackIP(net), a.Zone}
  }
  
  func (c *IPConn) readFrom(b []byte) (int, *IPAddr, error) {
  	// TODO(cw,rsc): consider using readv if we know the family
  	// type to avoid the header trim/copy
  	var addr *IPAddr
  	n, sa, err := c.fd.readFrom(b)
  	switch sa := sa.(type) {
  	case *syscall.SockaddrInet4:
  		addr = &IPAddr{IP: sa.Addr[0:]}
  		n = stripIPv4Header(n, b)
  	case *syscall.SockaddrInet6:
  		addr = &IPAddr{IP: sa.Addr[0:], Zone: zoneCache.name(int(sa.ZoneId))}
  	}
  	return n, addr, err
  }
  
  func stripIPv4Header(n int, b []byte) int {
  	if len(b) < 20 {
  		return n
  	}
  	l := int(b[0]&0x0f) << 2
  	if 20 > l || l > len(b) {
  		return n
  	}
  	if b[0]>>4 != 4 {
  		return n
  	}
  	copy(b, b[l:])
  	return n - l
  }
  
  func (c *IPConn) readMsg(b, oob []byte) (n, oobn, flags int, addr *IPAddr, err error) {
  	var sa syscall.Sockaddr
  	n, oobn, flags, sa, err = c.fd.readMsg(b, oob)
  	switch sa := sa.(type) {
  	case *syscall.SockaddrInet4:
  		addr = &IPAddr{IP: sa.Addr[0:]}
  	case *syscall.SockaddrInet6:
  		addr = &IPAddr{IP: sa.Addr[0:], Zone: zoneCache.name(int(sa.ZoneId))}
  	}
  	return
  }
  
  func (c *IPConn) writeTo(b []byte, addr *IPAddr) (int, error) {
  	if c.fd.isConnected {
  		return 0, ErrWriteToConnected
  	}
  	if addr == nil {
  		return 0, errMissingAddress
  	}
  	sa, err := addr.sockaddr(c.fd.family)
  	if err != nil {
  		return 0, err
  	}
  	return c.fd.writeTo(b, sa)
  }
  
  func (c *IPConn) writeMsg(b, oob []byte, addr *IPAddr) (n, oobn int, err error) {
  	if c.fd.isConnected {
  		return 0, 0, ErrWriteToConnected
  	}
  	if addr == nil {
  		return 0, 0, errMissingAddress
  	}
  	sa, err := addr.sockaddr(c.fd.family)
  	if err != nil {
  		return 0, 0, err
  	}
  	return c.fd.writeMsg(b, oob, sa)
  }
  
  func dialIP(ctx context.Context, netProto string, laddr, raddr *IPAddr) (*IPConn, error) {
  	network, proto, err := parseNetwork(ctx, netProto, true)
  	if err != nil {
  		return nil, err
  	}
  	switch network {
  	case "ip", "ip4", "ip6":
  	default:
  		return nil, UnknownNetworkError(netProto)
  	}
  	if raddr == nil {
  		return nil, errMissingAddress
  	}
  	fd, err := internetSocket(ctx, network, laddr, raddr, syscall.SOCK_RAW, proto, "dial")
  	if err != nil {
  		return nil, err
  	}
  	return newIPConn(fd), nil
  }
  
  func listenIP(ctx context.Context, netProto string, laddr *IPAddr) (*IPConn, error) {
  	network, proto, err := parseNetwork(ctx, netProto, true)
  	if err != nil {
  		return nil, err
  	}
  	switch network {
  	case "ip", "ip4", "ip6":
  	default:
  		return nil, UnknownNetworkError(netProto)
  	}
  	fd, err := internetSocket(ctx, network, laddr, nil, syscall.SOCK_RAW, proto, "listen")
  	if err != nil {
  		return nil, err
  	}
  	return newIPConn(fd), nil
  }
  

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