mirror of
https://github.com/qdm12/gluetun.git
synced 2026-05-07 04:20:12 +02:00
Quentin McGaw
be92aa2ac4
- Existing option `WIREGUARD_MTU` , if set, disables PMTUD and is used - New option `PMTUD_ICMP_ADDRESSES=1.1.1.1,8.8.8.8` and `PMTUD_TCP_ADDRESSES=1.1.1.1:443,8.8.8.8:443` - ICMP PMTUD now targets external-by-default IP addresses - New TCP PMTUD (binary search only) as a second MTU confirmation and fallback mechanism. - Force set TCP MSS to MTU - IP header - TCP base header - "magic 20 bytes" 🎆 - Fix #3108
77 lines
2.5 KiB
Go
77 lines
2.5 KiB
Go
package pmtud
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import (
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"context"
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"errors"
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"fmt"
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"net/netip"
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"time"
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"github.com/qdm12/gluetun/internal/pmtud/constants"
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"github.com/qdm12/gluetun/internal/pmtud/icmp"
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"github.com/qdm12/gluetun/internal/pmtud/tcp"
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)
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// PathMTUDiscover discovers the maximum MTU using both ICMP and TCP.
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// Multiple ICMP addresses and TCP addresses can be specified for redundancy.
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// ICMP PMTUD is run first. If successful, the range of possible MTU values to
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// check for TCP PMTUD is reduced to [maxMTU-150, maxMTU] where maxMTU is the
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// maximum MTU found with ICMP PMTUD. Otherwise, TCP PMTUD is run with the
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// whole range of possible MTU values up to the physical link MTU to check.
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// If the physicalLinkMTU is zero, it defaults to 1500 which is the ethernet standard MTU.
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// If the pingTimeout is zero, it defaults to 1 second.
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// If the logger is nil, a no-op logger is used.
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// It returns [ErrMTUNotFound] if the MTU could not be determined.
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func PathMTUDiscover(ctx context.Context, icmpAddrs []netip.Addr, tcpAddrs []netip.AddrPort,
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physicalLinkMTU uint32, tryTimeout time.Duration, logger Logger) (
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mtu uint32, err error,
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) {
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if physicalLinkMTU == 0 {
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const ethernetStandardMTU = 1500
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physicalLinkMTU = ethernetStandardMTU
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}
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if tryTimeout == 0 {
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tryTimeout = time.Second
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}
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if logger == nil {
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logger = &noopLogger{}
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}
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// Try finding the MTU using ICMP
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maxPossibleMTU := physicalLinkMTU
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icmpSuccess := false
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for _, icmpIP := range icmpAddrs {
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mtu, err := icmp.PathMTUDiscover(ctx, icmpIP, physicalLinkMTU,
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tryTimeout, logger)
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switch {
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case err == nil:
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logger.Debugf("ICMP path MTU discovery against %s found maximum valid MTU %d", icmpIP, mtu)
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icmpSuccess = true
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maxPossibleMTU = mtu
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case errors.Is(err, icmp.ErrNotPermitted), errors.Is(err, icmp.ErrMTUNotFound):
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logger.Debugf("ICMP path MTU discovery failed: %s", err)
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default:
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return 0, fmt.Errorf("ICMP path MTU discovery: %w", err)
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}
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}
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for _, addrPort := range tcpAddrs {
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minMTU := constants.MinIPv4MTU
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if addrPort.Addr().Is6() {
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minMTU = constants.MinIPv6MTU
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}
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if icmpSuccess {
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const mtuMargin = 150
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minMTU = max(maxPossibleMTU-mtuMargin, minMTU)
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}
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mtu, err = tcp.PathMTUDiscover(ctx, addrPort, minMTU, maxPossibleMTU, logger)
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if err != nil {
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logger.Debugf("TCP path MTU discovery to %s failed: %s", addrPort, err)
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continue
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}
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logger.Debugf("TCP path MTU discovery to %s found maximum valid MTU %d", addrPort, mtu)
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return mtu, nil
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}
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return 0, fmt.Errorf("TCP path MTU discovery: last error: %w", err)
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}
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