mirror of
https://github.com/slackhq/nebula.git
synced 2026-08-15 10:36:57 +02:00
JackDoan
91 lines
3.2 KiB
Go
91 lines
3.2 KiB
Go
package udp
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import (
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"net/netip"
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"github.com/slackhq/nebula/config"
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)
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const MTU = 9001
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// MaxWriteBatch is the largest batch any Conn.WriteBatch implementation is
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// required to accept. Callers SHOULD NOT pass more than this per call; Linux
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// backends preallocate sendmmsg scratch sized to this value, so exceeding it
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// only costs additional sendmmsg chunks within a single WriteBatch call.
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const MaxWriteBatch = 128
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// RxMeta carries per-packet metadata extracted from the RX path (ancillary
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// data, kernel offload state, etc.) and passed to EncReader callbacks.
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// Backends that do not produce a particular signal leave its zero value.
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//
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// OuterECN is the 2-bit IP-level ECN codepoint stamped on the carrier
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// datagram (extracted from IP_TOS / IPV6_TCLASS cmsg on Linux). Zero
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// means Not-ECT, which is also the value backends without ECN RX support
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// supply on every packet.
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type RxMeta struct {
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OuterECN byte
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}
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type EncReader func(
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addr netip.AddrPort,
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payload []byte,
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meta RxMeta,
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)
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type Conn interface {
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Rebind() error
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LocalAddr() (netip.AddrPort, error)
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// ListenOut invokes r for each received packet.
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// On batch-capable backends (recvmmsg), flush is called after each batch is fully delivered.
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// Callers use it to flush per-batch accumulators such as TUN write coalescers.
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// Single-packet backends call flush after each packet. flush must not be nil.
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ListenOut(r EncReader, flush func()) error
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// WriteTo sends a single packet to addr.
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// outerECN is the 2-bit IP-level ECN codepoint to stamp on the packet's outer IP header.
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// 0 (Not-ECT) is the pass-through value.
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// Linux attaches it as an IP_TOS / IPV6_TCLASS cmsg. Backends without per-packet ECN support ignore it.
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WriteTo(b []byte, addr netip.AddrPort, outerECN byte) error
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// WriteBatch sends a contiguous batch of packets, each with its own
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// destination. bufs and addrs must have the same length. outerECNs may
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// be nil (treated as all-zero / Not-ECT); when non-nil it must have the
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// same length as bufs, and outerECNs[i] is the 2-bit IP-level ECN
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// codepoint to set on packet i's outer header. Linux uses sendmmsg(2)
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// for a single syscall and attaches the value as IP_TOS / IPV6_TCLASS
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// cmsg; other backends ignore it.
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//
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// Returns the number of packets successfully written. A destination the kernel rejects costs only
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// its own packet, so a short count means some peers were undeliverable, not that the batch failed.
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// Not safe for concurrent use on the same Conn.
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WriteBatch(bufs [][]byte, addrs []netip.AddrPort, outerECNs []byte) (int, error)
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ReloadConfig(c *config.C)
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SupportsMultipleReaders() bool
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Close() error
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}
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type NoopConn struct{}
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func (NoopConn) Rebind() error {
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return nil
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}
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func (NoopConn) LocalAddr() (netip.AddrPort, error) {
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return netip.AddrPort{}, nil
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}
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func (NoopConn) ListenOut(_ EncReader, _ func()) error {
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return nil
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}
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func (NoopConn) SupportsMultipleReaders() bool {
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return false
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}
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func (NoopConn) WriteTo(_ []byte, _ netip.AddrPort, _ byte) error {
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return nil
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}
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func (NoopConn) WriteBatch(bufs [][]byte, _ []netip.AddrPort, _ []byte) (int, error) {
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return len(bufs), nil
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}
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func (NoopConn) ReloadConfig(_ *config.C) {
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return
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}
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func (NoopConn) Close() error {
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return nil
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}
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