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package quic
import (
"io"
"log"
"net"
"os"
"strconv"
"strings"
"syscall"
"time"
"github.com/quic-go/quic-go/internal/protocol"
"github.com/quic-go/quic-go/internal/utils"
)
type connCapabilities struct {
// This connection has the Don't Fragment (DF) bit set.
// This means it makes to run DPLPMTUD.
DF bool
// GSO (Generic Segmentation Offload) supported
GSO bool
// ECN (Explicit Congestion Notifications) supported
ECN bool
}
// rawConn is a connection that allow reading of a receivedPackeh.
type rawConn interface {
ReadPacket() (receivedPacket, error)
// WritePacket writes a packet on the wire.
// gsoSize is the size of a single packet, or 0 to disable GSO.
// It is invalid to set gsoSize if capabilities.GSO is not set.
WritePacket(b []byte, addr net.Addr, packetInfoOOB []byte, gsoSize uint16, ecn protocol.ECN) (int, error)
LocalAddr() net.Addr
SetReadDeadline(time.Time) error
io.Closer
capabilities() connCapabilities
}
// OOBCapablePacketConn is a connection that allows the reading of ECN bits from the IP header.
// If the PacketConn passed to the [Transport] satisfies this interface, quic-go will use it.
// In this case, ReadMsgUDP() will be used instead of ReadFrom() to read packets.
type OOBCapablePacketConn interface {
net.PacketConn
SyscallConn() (syscall.RawConn, error)
SetReadBuffer(int) error
ReadMsgUDP(b, oob []byte) (n, oobn, flags int, addr *net.UDPAddr, err error)
WriteMsgUDP(b, oob []byte, addr *net.UDPAddr) (n, oobn int, err error)
}
var _ OOBCapablePacketConn = &net.UDPConn{}
func wrapConn(pc net.PacketConn) (rawConn, error) {
if err := setReceiveBuffer(pc); err != nil {
if !strings.Contains(err.Error(), "use of closed network connection") {
setBufferWarningOnce.Do(func() {
if disable, _ := strconv.ParseBool(os.Getenv("QUIC_GO_DISABLE_RECEIVE_BUFFER_WARNING")); disable {
return
}
log.Printf("%s. See https://github.com/quic-go/quic-go/wiki/UDP-Buffer-Sizes for details.", err)
})
}
}
if err := setSendBuffer(pc); err != nil {
if !strings.Contains(err.Error(), "use of closed network connection") {
setBufferWarningOnce.Do(func() {
if disable, _ := strconv.ParseBool(os.Getenv("QUIC_GO_DISABLE_RECEIVE_BUFFER_WARNING")); disable {
return
}
log.Printf("%s. See https://github.com/quic-go/quic-go/wiki/UDP-Buffer-Sizes for details.", err)
})
}
}
conn, ok := pc.(interface {
SyscallConn() (syscall.RawConn, error)
})
var supportsDF bool
if ok {
rawConn, err := conn.SyscallConn()
if err != nil {
return nil, err
}
// only set DF on UDP sockets
if _, ok := pc.LocalAddr().(*net.UDPAddr); ok {
var err error
supportsDF, err = setDF(rawConn)
if err != nil {
return nil, err
}
}
}
c, ok := pc.(OOBCapablePacketConn)
if !ok {
utils.DefaultLogger.Infof("PacketConn is not a net.UDPConn. Disabling optimizations possible on UDP connections.")
return &basicConn{PacketConn: pc, supportsDF: supportsDF}, nil
}
return newConn(c, supportsDF)
}
// The basicConn is the most trivial implementation of a rawConn.
// It reads a single packet from the underlying net.PacketConn.
// It is used when
// * the net.PacketConn is not a OOBCapablePacketConn, and
// * when the OS doesn't support OOB.
type basicConn struct {
net.PacketConn
supportsDF bool
}
var _ rawConn = &basicConn{}
func (c *basicConn) ReadPacket() (receivedPacket, error) {
buffer := getPacketBuffer()
// The packet size should not exceed protocol.MaxPacketBufferSize bytes
// If it does, we only read a truncated packet, which will then end up undecryptable
buffer.Data = buffer.Data[:protocol.MaxPacketBufferSize]
n, addr, err := c.ReadFrom(buffer.Data)
if err != nil {
return receivedPacket{}, err
}
return receivedPacket{
remoteAddr: addr,
rcvTime: time.Now(),
data: buffer.Data[:n],
buffer: buffer,
}, nil
}
func (c *basicConn) WritePacket(b []byte, addr net.Addr, _ []byte, gsoSize uint16, ecn protocol.ECN) (n int, err error) {
if gsoSize != 0 {
panic("cannot use GSO with a basicConn")
}
if ecn != protocol.ECNUnsupported {
panic("cannot use ECN with a basicConn")
}
return c.WriteTo(b, addr)
}
func (c *basicConn) capabilities() connCapabilities { return connCapabilities{DF: c.supportsDF} }
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