mirror of
https://github.com/qdm12/gluetun.git
synced 2026-05-06 20:10:11 +02:00
Quentin McGaw
4a78989d9d
- main reason being it's a burden to always define sentinel errors at global scope, wrap them with `%w` instead of using a string directly - only use sentinel errors when it has to be checked using `errors.Is` - replace all usage of these sentinel errors in `fmt.Errorf` with direct strings that were in the sentinel error - exclude the sentinel error definition requirement from .golangci.yml - update unit tests to use ContainersError instead of ErrorIs so it stays as a "not a change detector test" without requiring a sentinel error
53 lines
1.7 KiB
Go
53 lines
1.7 KiB
Go
package icmp
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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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)
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// PathMTUDiscover discovers the path MTU to the given IP address
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// using ICMP.
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// It first tries to get the next hop MTU using ICMP messages.
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// If that fails, it falls back to sending echo requests with
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// different packet sizes to find the maximum MTU.
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// The function returns [ErrMTUNotFound] if the MTU could not be determined.
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func PathMTUDiscover(ctx context.Context, ip netip.Addr,
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physicalLinkMTU uint32, timeout time.Duration, logger Logger,
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) (mtu uint32, err error) {
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if ip.Is4() {
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logger.Debugf("finding IPv4 next hop MTU to %s", ip)
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mtu, err = findIPv4NextHopMTU(ctx, ip, physicalLinkMTU, timeout, logger)
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switch {
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case err == nil:
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return mtu, nil
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case errors.Is(err, errTimeout) || errors.Is(err, errCommunicationAdministrativelyProhibited): // blackhole
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default:
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return 0, fmt.Errorf("finding IPv4 next hop MTU to %s: %w", ip, err)
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}
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} else {
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logger.Debugf("requesting IPv6 ICMP packet-too-big reply from %s", ip)
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mtu, err = getIPv6PacketTooBig(ctx, ip, physicalLinkMTU, timeout, logger)
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switch {
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case err == nil:
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return mtu, nil
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case errors.Is(err, errTimeout): // blackhole
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default:
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return 0, fmt.Errorf("getting IPv6 packet-too-big message: %w", err)
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}
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}
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// Fall back method: send echo requests with different packet
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// sizes and check which ones succeed to find the maximum MTU.
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logger.Debugf("falling back to sending different sized echo packets to %s", ip)
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minMTU := constants.MinIPv4MTU
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if ip.Is6() {
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minMTU = constants.MinIPv6MTU
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}
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return pmtudMultiSizes(ctx, ip, minMTU, physicalLinkMTU, timeout, logger)
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}
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