46 lines
1,021 B
Go
46 lines
1,021 B
Go
package main
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import (
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"sync"
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"time"
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"github.com/sfiera/multitalk/pkg/ddp"
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"github.com/sfiera/multitalk/pkg/ethernet"
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)
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// TODO: verify this parameter
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const maxAMTEntryAge = 30 * time.Second
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type amtEntry struct {
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hwAddr ethernet.Addr
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last time.Time
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}
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// AMT implements a concurrent-safe Address Mapping Table for AppleTalk (DDP)
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// addresses to Ethernet hardware addresses.
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type AMT struct {
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mu sync.RWMutex
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table map[ddp.Addr]amtEntry
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}
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// Learn adds or updates an AMT entry.
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func (t *AMT) Learn(ddpAddr ddp.Addr, hwAddr ethernet.Addr) {
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t.mu.Lock()
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defer t.mu.Unlock()
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if t.table == nil {
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t.table = make(map[ddp.Addr]amtEntry)
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}
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t.table[ddpAddr] = amtEntry{
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hwAddr: hwAddr,
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last: time.Now(),
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}
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}
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// Lookup searches for a non-expired entry in the table only. It does not send
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// any packets.
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func (t *AMT) Lookup(ddpAddr ddp.Addr) (ethernet.Addr, bool) {
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t.mu.RLock()
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defer t.mu.RUnlock()
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ent, ok := t.table[ddpAddr]
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return ent.hwAddr, ok && time.Since(ent.last) < maxAMTEntryAge
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}
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