rclone/fs/fshttp/dialer.go

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package fshttp
import (
"context"
"net"
"runtime"
"strings"
"sync"
"time"
"github.com/rclone/rclone/fs"
"github.com/rclone/rclone/fs/accounting"
"golang.org/x/net/ipv4"
"golang.org/x/net/ipv6"
)
// Dialer structure contains default dialer and timeout, tclass support
type Dialer struct {
net.Dialer
timeout time.Duration
tclass int
}
// NewDialer creates a Dialer structure with Timeout, Keepalive,
// LocalAddr and DSCP set from rclone flags.
func NewDialer(ctx context.Context) *Dialer {
ci := fs.GetConfig(ctx)
dialer := &Dialer{
Dialer: net.Dialer{
Timeout: ci.ConnectTimeout,
KeepAlive: 30 * time.Second,
},
timeout: ci.Timeout,
tclass: int(ci.TrafficClass),
}
if ci.BindAddr != nil {
dialer.Dialer.LocalAddr = &net.TCPAddr{IP: ci.BindAddr}
}
return dialer
}
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// Dial connects to the network address.
func (d *Dialer) Dial(network, address string) (net.Conn, error) {
return d.DialContext(context.Background(), network, address)
}
var warnDSCPFail, warnDSCPWindows sync.Once
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// DialContext connects to the network address using the provided context.
func (d *Dialer) DialContext(ctx context.Context, network, address string) (net.Conn, error) {
// If local address is 0.0.0.0 or ::0 force IPv4 or IPv6
// This works around https://github.com/golang/go/issues/48723
// Which means 0.0.0.0 and ::0 both bind to both IPv4 and IPv6
if ip, ok := d.Dialer.LocalAddr.(*net.TCPAddr); ok && ip.IP.IsUnspecified() && (network == "tcp" || network == "udp") {
if ip.IP.To4() != nil {
network += "4" // IPv4 address
} else {
network += "6" // IPv6 address
}
}
c, err := d.Dialer.DialContext(ctx, network, address)
if err != nil {
return c, err
}
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if d.tclass != 0 {
// IPv6 addresses must have two or more ":"
if strings.Count(c.RemoteAddr().String(), ":") > 1 {
err = ipv6.NewConn(c).SetTrafficClass(d.tclass)
} else {
err = ipv4.NewConn(c).SetTOS(d.tclass)
// Warn of silent failure on Windows (IPv4 only, IPv6 caught by error handler)
if runtime.GOOS == "windows" {
warnDSCPWindows.Do(func() {
fs.LogLevelPrintf(fs.LogLevelWarning, nil, "dialer: setting DSCP on Windows/IPv4 fails silently; see https://github.com/golang/go/issues/42728")
})
}
}
if err != nil {
warnDSCPFail.Do(func() {
fs.LogLevelPrintf(fs.LogLevelWarning, nil, "dialer: failed to set DSCP socket options: %v", err)
})
}
}
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t := &timeoutConn{
Conn: c,
timeout: d.timeout,
}
return t, t.nudgeDeadline()
}
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// A net.Conn that sets deadline for every Read/Write operation
type timeoutConn struct {
net.Conn
timeout time.Duration
}
// Nudge the deadline for an idle timeout on by c.timeout if non-zero
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func (c *timeoutConn) nudgeDeadline() error {
if c.timeout > 0 {
return c.SetDeadline(time.Now().Add(c.timeout))
}
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return nil
}
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// Read bytes with rate limiting and idle timeouts
func (c *timeoutConn) Read(b []byte) (n int, err error) {
// Ideally we would LimitBandwidth(len(b)) here and replace tokens we didn't use
n, err = c.Conn.Read(b)
accounting.TokenBucket.LimitBandwidth(accounting.TokenBucketSlotTransportRx, n)
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if err == nil && n > 0 && c.timeout > 0 {
err = c.nudgeDeadline()
}
return n, err
}
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// Write bytes with rate limiting and idle timeouts
func (c *timeoutConn) Write(b []byte) (n int, err error) {
accounting.TokenBucket.LimitBandwidth(accounting.TokenBucketSlotTransportTx, len(b))
n, err = c.Conn.Write(b)
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if err == nil && n > 0 && c.timeout > 0 {
err = c.nudgeDeadline()
}
return n, err
}