github.com/danielpfeifer02/quic-go-prio-packs@v0.41.0-28/sys_conn.go (about)

     1  package quic
     2  
     3  import (
     4  	"log"
     5  	"net"
     6  	"os"
     7  	"strconv"
     8  	"strings"
     9  	"syscall"
    10  	"time"
    11  
    12  	"github.com/danielpfeifer02/quic-go-prio-packs/internal/protocol"
    13  	"github.com/danielpfeifer02/quic-go-prio-packs/internal/utils"
    14  )
    15  
    16  // OOBCapablePacketConn is a connection that allows the reading of ECN bits from the IP header.
    17  // If the PacketConn passed to Dial or Listen satisfies this interface, quic-go will use it.
    18  // In this case, ReadMsgUDP() will be used instead of ReadFrom() to read packets.
    19  type OOBCapablePacketConn interface {
    20  	net.PacketConn
    21  	SyscallConn() (syscall.RawConn, error)
    22  	SetReadBuffer(int) error
    23  	ReadMsgUDP(b, oob []byte) (n, oobn, flags int, addr *net.UDPAddr, err error)
    24  	WriteMsgUDP(b, oob []byte, addr *net.UDPAddr) (n, oobn int, err error)
    25  }
    26  
    27  var _ OOBCapablePacketConn = &net.UDPConn{}
    28  
    29  func wrapConn(pc net.PacketConn) (rawConn, error) {
    30  	if err := setReceiveBuffer(pc); err != nil {
    31  		if !strings.Contains(err.Error(), "use of closed network connection") {
    32  			setBufferWarningOnce.Do(func() {
    33  				if disable, _ := strconv.ParseBool(os.Getenv("QUIC_GO_DISABLE_RECEIVE_BUFFER_WARNING")); disable {
    34  					return
    35  				}
    36  				log.Printf("%s. See https://github.com/danielpfeifer02/quic-go-prio-packs/wiki/UDP-Buffer-Sizes for details.", err)
    37  			})
    38  		}
    39  	}
    40  	if err := setSendBuffer(pc); err != nil {
    41  		if !strings.Contains(err.Error(), "use of closed network connection") {
    42  			setBufferWarningOnce.Do(func() {
    43  				if disable, _ := strconv.ParseBool(os.Getenv("QUIC_GO_DISABLE_RECEIVE_BUFFER_WARNING")); disable {
    44  					return
    45  				}
    46  				log.Printf("%s. See https://github.com/danielpfeifer02/quic-go-prio-packs/wiki/UDP-Buffer-Sizes for details.", err)
    47  			})
    48  		}
    49  	}
    50  
    51  	conn, ok := pc.(interface {
    52  		SyscallConn() (syscall.RawConn, error)
    53  	})
    54  	var supportsDF bool
    55  	if ok {
    56  		rawConn, err := conn.SyscallConn()
    57  		if err != nil {
    58  			return nil, err
    59  		}
    60  
    61  		if _, ok := pc.LocalAddr().(*net.UDPAddr); ok {
    62  			// Only set DF on sockets that we expect to be able to handle that configuration.
    63  			var err error
    64  			supportsDF, err = setDF(rawConn)
    65  			if err != nil {
    66  				return nil, err
    67  			}
    68  		}
    69  	}
    70  	c, ok := pc.(OOBCapablePacketConn)
    71  	if !ok {
    72  		utils.DefaultLogger.Infof("PacketConn is not a net.UDPConn. Disabling optimizations possible on UDP connections.")
    73  		return &basicConn{PacketConn: pc, supportsDF: supportsDF}, nil
    74  	}
    75  	return newConn(c, supportsDF)
    76  }
    77  
    78  // The basicConn is the most trivial implementation of a rawConn.
    79  // It reads a single packet from the underlying net.PacketConn.
    80  // It is used when
    81  // * the net.PacketConn is not a OOBCapablePacketConn, and
    82  // * when the OS doesn't support OOB.
    83  type basicConn struct {
    84  	net.PacketConn
    85  	supportsDF bool
    86  }
    87  
    88  var _ rawConn = &basicConn{}
    89  
    90  func (c *basicConn) ReadPacket() (receivedPacket, error) {
    91  	buffer := getPacketBuffer()
    92  	// The packet size should not exceed protocol.MaxPacketBufferSize bytes
    93  	// If it does, we only read a truncated packet, which will then end up undecryptable
    94  	buffer.Data = buffer.Data[:protocol.MaxPacketBufferSize]
    95  	n, addr, err := c.PacketConn.ReadFrom(buffer.Data)
    96  	if err != nil {
    97  		return receivedPacket{}, err
    98  	}
    99  	return receivedPacket{
   100  		remoteAddr: addr,
   101  		rcvTime:    time.Now(),
   102  		data:       buffer.Data[:n],
   103  		buffer:     buffer,
   104  	}, nil
   105  }
   106  
   107  func (c *basicConn) WritePacket(b []byte, addr net.Addr, _ []byte, gsoSize uint16, ecn protocol.ECN) (n int, err error) {
   108  	if gsoSize != 0 {
   109  		panic("cannot use GSO with a basicConn")
   110  	}
   111  	if ecn != protocol.ECNUnsupported {
   112  		panic("cannot use ECN with a basicConn")
   113  	}
   114  	return c.PacketConn.WriteTo(b, addr)
   115  }
   116  
   117  func (c *basicConn) capabilities() connCapabilities { return connCapabilities{DF: c.supportsDF} }