84 lines
2.2 KiB
Go
84 lines
2.2 KiB
Go
// Copyright (C) 2019 The Syncthing Authors.
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//
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// This Source Code Form is subject to the terms of the Mozilla Public
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// License, v. 2.0. If a copy of the MPL was not distributed with this file,
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// You can obtain one at https://mozilla.org/MPL/2.0/.
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// Registry tracks connections/addresses on which we are listening on, to allow us to pick a connection/address that
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// has a NAT port mapping. This also makes our outgoing port stable and same as incoming port which should allow
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// better probability of punching through.
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package registry
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import (
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"strings"
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"github.com/syncthing/syncthing/lib/sync"
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)
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type Registry struct {
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mut sync.Mutex
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available map[string][]interface{}
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}
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func New() *Registry {
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return &Registry{
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mut: sync.NewMutex(),
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available: make(map[string][]interface{}),
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}
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}
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func (r *Registry) Register(scheme string, item interface{}) {
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r.mut.Lock()
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defer r.mut.Unlock()
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r.available[scheme] = append(r.available[scheme], item)
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}
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func (r *Registry) Unregister(scheme string, item interface{}) {
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r.mut.Lock()
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defer r.mut.Unlock()
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candidates := r.available[scheme]
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for i, existingItem := range candidates {
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if existingItem == item {
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candidates[i] = candidates[len(candidates)-1]
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candidates[len(candidates)-1] = nil
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r.available[scheme] = candidates[:len(candidates)-1]
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break
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}
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}
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}
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// Get returns an item for a schema compatible with the given scheme.
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// If any item satisfies preferred, that has precedence over other items.
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func (r *Registry) Get(scheme string, preferred func(interface{}) bool) interface{} {
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r.mut.Lock()
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defer r.mut.Unlock()
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var (
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best interface{}
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bestPref bool
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bestScheme string
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)
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for availableScheme, items := range r.available {
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// quic:// should be considered ok for both quic4:// and quic6://
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if !strings.HasPrefix(scheme, availableScheme) {
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continue
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}
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for _, item := range items {
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better := best == nil
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pref := preferred(item)
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if !better {
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// In case of a tie, prefer "quic" to "quic[46]" etc.
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better = pref &&
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(!bestPref || len(availableScheme) < len(bestScheme))
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}
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if !better {
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continue
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}
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best, bestPref, bestScheme = item, pref, availableScheme
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}
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}
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return best
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}
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