mirror of
https://github.com/impact-eintr/netstack.git
synced 2025-10-08 06:10:04 +08:00
wsl code edit
This commit is contained in:
impact-eintr
@@ -1,308 +1,308 @@
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// Copyright 2018 Google LLC
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package stack
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import (
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"fmt"
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"log"
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"sync"
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"time"
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"netstack/sleep"
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"netstack/tcpip"
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)
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const linkAddrCacheSize = 512 // max cache entries
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// linkAddrCache is a fixed-sized cache mapping IP addresses to link addresses.
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//
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// The entries are stored in a ring buffer, oldest entry replaced first.
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//
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// This struct is safe for concurrent use.
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type linkAddrCache struct {
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// ageLimit is how long a cache entry is valid for.
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ageLimit time.Duration
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// resolutionTimeout is the amount of time to wait for a link request to
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// resolve an address.
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resolutionTimeout time.Duration
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// resolutionAttempts is the number of times an address is attempted to be
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// resolved before failing.
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resolutionAttempts int
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mu sync.Mutex
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cache map[tcpip.FullAddress]*linkAddrEntry
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next int // array index of next available entry
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entries [linkAddrCacheSize]linkAddrEntry
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}
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// entryState controls the state of a single entry in the cache.
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type entryState int
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const (
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// incomplete means that there is an outstanding request to resolve the
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// address. This is the initial state.
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incomplete entryState = iota
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// ready means that the address has been resolved and can be used.
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ready
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// failed means that address resolution timed out and the address
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// could not be resolved.
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failed
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// expired means that the cache entry has expired and the address must be
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// resolved again.
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expired
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)
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// String implements Stringer.
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func (s entryState) String() string {
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switch s {
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case incomplete:
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return "incomplete"
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case ready:
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return "ready"
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case failed:
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return "failed"
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case expired:
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return "expired"
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default:
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return fmt.Sprintf("unknown(%d)", s)
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}
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}
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// A linkAddrEntry is an entry in the linkAddrCache.
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// This struct is thread-compatible.
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type linkAddrEntry struct {
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addr tcpip.FullAddress
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linkAddr tcpip.LinkAddress
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expiration time.Time
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s entryState
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// wakers is a set of waiters for address resolution result. Anytime
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// state transitions out of 'incomplete' these waiters are notified.
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wakers map[*sleep.Waker]struct{}
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done chan struct{}
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}
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func (e *linkAddrEntry) state() entryState {
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if e.s != expired && time.Now().After(e.expiration) {
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// Force the transition to ensure waiters are notified.
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e.changeState(expired)
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}
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return e.s
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}
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func (e *linkAddrEntry) changeState(ns entryState) {
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if e.s == ns {
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return
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}
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// Validate state transition.
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switch e.s {
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case incomplete:
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// All transitions are valid.
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case ready, failed:
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if ns != expired {
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panic(fmt.Sprintf("invalid state transition from %s to %s", e.s, ns))
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}
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case expired:
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// Terminal state.
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panic(fmt.Sprintf("invalid state transition from %s to %s", e.s, ns))
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default:
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panic(fmt.Sprintf("invalid state: %s", e.s))
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}
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// Notify whoever is waiting on address resolution when transitioning
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// out of 'incomplete'.
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if e.s == incomplete {
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for w := range e.wakers {
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w.Assert()
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}
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e.wakers = nil
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if e.done != nil {
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close(e.done)
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}
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}
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e.s = ns
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}
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func (e *linkAddrEntry) addWaker(w *sleep.Waker) {
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e.wakers[w] = struct{}{}
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}
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func (e *linkAddrEntry) removeWaker(w *sleep.Waker) {
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delete(e.wakers, w)
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}
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// add adds a k -> v mapping to the cache.
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func (c *linkAddrCache) add(k tcpip.FullAddress, v tcpip.LinkAddress) {
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log.Printf("add link cache: %v-%v", k, v)
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c.mu.Lock()
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defer c.mu.Unlock()
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entry, ok := c.cache[k]
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if ok {
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s := entry.state()
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if s != expired && entry.linkAddr == v {
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// Disregard repeated calls.
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return
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}
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// Check if entry is waiting for address resolution.
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if s == incomplete {
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entry.linkAddr = v
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} else {
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// Otherwise create a new entry to replace it.
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entry = c.makeAndAddEntry(k, v)
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}
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} else {
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entry = c.makeAndAddEntry(k, v)
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}
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entry.changeState(ready)
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}
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// makeAndAddEntry is a helper function to create and add a new
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// entry to the cache map and evict older entry as needed.
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func (c *linkAddrCache) makeAndAddEntry(k tcpip.FullAddress, v tcpip.LinkAddress) *linkAddrEntry {
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// Take over the next entry.
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entry := &c.entries[c.next]
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if c.cache[entry.addr] == entry {
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delete(c.cache, entry.addr)
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}
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// Mark the soon-to-be-replaced entry as expired, just in case there is
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// someone waiting for address resolution on it.
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entry.changeState(expired)
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*entry = linkAddrEntry{
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addr: k,
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linkAddr: v,
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expiration: time.Now().Add(c.ageLimit),
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wakers: make(map[*sleep.Waker]struct{}),
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done: make(chan struct{}),
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}
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c.cache[k] = entry
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c.next = (c.next + 1) % len(c.entries)
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return entry
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}
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// get reports any known link address for k.
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func (c *linkAddrCache) get(k tcpip.FullAddress, linkRes LinkAddressResolver, localAddr tcpip.Address, linkEP LinkEndpoint, waker *sleep.Waker) (tcpip.LinkAddress, <-chan struct{}, *tcpip.Error) {
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log.Printf("link addr get linkRes: %#v, addr: %+v", linkRes, k)
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if linkRes != nil {
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if addr, ok := linkRes.ResolveStaticAddress(k.Addr); ok {
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return addr, nil, nil
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}
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}
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c.mu.Lock()
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defer c.mu.Unlock()
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// 尝试从缓存中得到MAC地址
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if entry, ok := c.cache[k]; ok {
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switch s := entry.state(); s {
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case expired:
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case ready:
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return entry.linkAddr, nil, nil
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case failed:
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return "", nil, tcpip.ErrNoLinkAddress
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case incomplete:
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// Address resolution is still in progress.
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entry.addWaker(waker)
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return "", entry.done, tcpip.ErrWouldBlock
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default:
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panic(fmt.Sprintf("invalid cache entry state: %s", s))
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}
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}
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if linkRes == nil {
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return "", nil, tcpip.ErrNoLinkAddress
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}
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// Add 'incomplete' entry in the cache to mark that resolution is in progress.
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e := c.makeAndAddEntry(k, "")
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e.addWaker(waker)
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go c.startAddressResolution(k, linkRes, localAddr, linkEP, e.done)
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return "", e.done, tcpip.ErrWouldBlock
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}
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// removeWaker removes a waker previously added through get().
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func (c *linkAddrCache) removeWaker(k tcpip.FullAddress, waker *sleep.Waker) {
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c.mu.Lock()
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defer c.mu.Unlock()
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if entry, ok := c.cache[k]; ok {
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entry.removeWaker(waker)
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}
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}
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func (c *linkAddrCache) startAddressResolution(k tcpip.FullAddress, linkRes LinkAddressResolver, localAddr tcpip.Address, linkEP LinkEndpoint, done <-chan struct{}) {
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for i := 0; ; i++ {
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// Send link request, then wait for the timeout limit and check
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// whether the request succeeded.
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linkRes.LinkAddressRequest(k.Addr, localAddr, linkEP)
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select {
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case <-time.After(c.resolutionTimeout):
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if stop := c.checkLinkRequest(k, i); stop {
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return
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}
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case <-done:
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return
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}
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}
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}
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// checkLinkRequest checks whether previous attempt to resolve address has succeeded
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// and mark the entry accordingly, e.g. ready, failed, etc. Return true if request
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// can stop, false if another request should be sent.
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func (c *linkAddrCache) checkLinkRequest(k tcpip.FullAddress, attempt int) bool {
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c.mu.Lock()
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defer c.mu.Unlock()
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entry, ok := c.cache[k]
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if !ok {
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// Entry was evicted from the cache.
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return true
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}
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switch s := entry.state(); s {
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case ready, failed, expired:
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// Entry was made ready by resolver or failed. Either way we're done.
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return true
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case incomplete:
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if attempt+1 >= c.resolutionAttempts {
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// Max number of retries reached, mark entry as failed.
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entry.changeState(failed)
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return true
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}
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// No response yet, need to send another ARP request.
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return false
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default:
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panic(fmt.Sprintf("invalid cache entry state: %s", s))
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}
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}
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func newLinkAddrCache(ageLimit, resolutionTimeout time.Duration, resolutionAttempts int) *linkAddrCache {
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return &linkAddrCache{
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ageLimit: ageLimit,
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resolutionTimeout: resolutionTimeout,
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resolutionAttempts: resolutionAttempts,
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cache: make(map[tcpip.FullAddress]*linkAddrEntry, linkAddrCacheSize),
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}
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}
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// Copyright 2018 Google LLC
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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||||
// you may not use this file except in compliance with the License.
|
||||
// You may obtain a copy of the License at
|
||||
//
|
||||
// http://www.apache.org/licenses/LICENSE-2.0
|
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//
|
||||
// Unless required by applicable law or agreed to in writing, software
|
||||
// distributed under the License is distributed on an "AS IS" BASIS,
|
||||
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
||||
// See the License for the specific language governing permissions and
|
||||
// limitations under the License.
|
||||
|
||||
package stack
|
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|
||||
import (
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"fmt"
|
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"log"
|
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"sync"
|
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"time"
|
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|
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"netstack/sleep"
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"netstack/tcpip"
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)
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|
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const linkAddrCacheSize = 512 // max cache entries
|
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|
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// linkAddrCache is a fixed-sized cache mapping IP addresses to link addresses.
|
||||
//
|
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// The entries are stored in a ring buffer, oldest entry replaced first.
|
||||
//
|
||||
// This struct is safe for concurrent use.
|
||||
type linkAddrCache struct {
|
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// ageLimit is how long a cache entry is valid for.
|
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ageLimit time.Duration
|
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|
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// resolutionTimeout is the amount of time to wait for a link request to
|
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// resolve an address.
|
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resolutionTimeout time.Duration
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|
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// resolutionAttempts is the number of times an address is attempted to be
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// resolved before failing.
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resolutionAttempts int
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mu sync.Mutex
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cache map[tcpip.FullAddress]*linkAddrEntry
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next int // array index of next available entry
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entries [linkAddrCacheSize]linkAddrEntry
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}
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|
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// entryState controls the state of a single entry in the cache.
|
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type entryState int
|
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|
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const (
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// incomplete means that there is an outstanding request to resolve the
|
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// address. This is the initial state.
|
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incomplete entryState = iota
|
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// ready means that the address has been resolved and can be used.
|
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ready
|
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// failed means that address resolution timed out and the address
|
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// could not be resolved.
|
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failed
|
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// expired means that the cache entry has expired and the address must be
|
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// resolved again.
|
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expired
|
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)
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|
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// String implements Stringer.
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func (s entryState) String() string {
|
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switch s {
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case incomplete:
|
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return "incomplete"
|
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case ready:
|
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return "ready"
|
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case failed:
|
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return "failed"
|
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case expired:
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return "expired"
|
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default:
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return fmt.Sprintf("unknown(%d)", s)
|
||||
}
|
||||
}
|
||||
|
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// A linkAddrEntry is an entry in the linkAddrCache.
|
||||
// This struct is thread-compatible.
|
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type linkAddrEntry struct {
|
||||
addr tcpip.FullAddress
|
||||
linkAddr tcpip.LinkAddress
|
||||
expiration time.Time
|
||||
s entryState
|
||||
|
||||
// wakers is a set of waiters for address resolution result. Anytime
|
||||
// state transitions out of 'incomplete' these waiters are notified.
|
||||
wakers map[*sleep.Waker]struct{}
|
||||
|
||||
done chan struct{}
|
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}
|
||||
|
||||
func (e *linkAddrEntry) state() entryState {
|
||||
if e.s != expired && time.Now().After(e.expiration) {
|
||||
// Force the transition to ensure waiters are notified.
|
||||
e.changeState(expired)
|
||||
}
|
||||
return e.s
|
||||
}
|
||||
|
||||
func (e *linkAddrEntry) changeState(ns entryState) {
|
||||
if e.s == ns {
|
||||
return
|
||||
}
|
||||
|
||||
// Validate state transition.
|
||||
switch e.s {
|
||||
case incomplete:
|
||||
// All transitions are valid.
|
||||
case ready, failed:
|
||||
if ns != expired {
|
||||
panic(fmt.Sprintf("invalid state transition from %s to %s", e.s, ns))
|
||||
}
|
||||
case expired:
|
||||
// Terminal state.
|
||||
panic(fmt.Sprintf("invalid state transition from %s to %s", e.s, ns))
|
||||
default:
|
||||
panic(fmt.Sprintf("invalid state: %s", e.s))
|
||||
}
|
||||
|
||||
// Notify whoever is waiting on address resolution when transitioning
|
||||
// out of 'incomplete'.
|
||||
if e.s == incomplete {
|
||||
for w := range e.wakers {
|
||||
w.Assert()
|
||||
}
|
||||
e.wakers = nil
|
||||
if e.done != nil {
|
||||
close(e.done)
|
||||
}
|
||||
}
|
||||
e.s = ns
|
||||
}
|
||||
|
||||
func (e *linkAddrEntry) addWaker(w *sleep.Waker) {
|
||||
e.wakers[w] = struct{}{}
|
||||
}
|
||||
|
||||
func (e *linkAddrEntry) removeWaker(w *sleep.Waker) {
|
||||
delete(e.wakers, w)
|
||||
}
|
||||
|
||||
// add adds a k -> v mapping to the cache.
|
||||
func (c *linkAddrCache) add(k tcpip.FullAddress, v tcpip.LinkAddress) {
|
||||
log.Printf("add link cache: %v-%v", k, v)
|
||||
c.mu.Lock()
|
||||
defer c.mu.Unlock()
|
||||
|
||||
entry, ok := c.cache[k]
|
||||
if ok {
|
||||
s := entry.state()
|
||||
if s != expired && entry.linkAddr == v {
|
||||
// Disregard repeated calls.
|
||||
return
|
||||
}
|
||||
// Check if entry is waiting for address resolution.
|
||||
if s == incomplete {
|
||||
entry.linkAddr = v
|
||||
} else {
|
||||
// Otherwise create a new entry to replace it.
|
||||
entry = c.makeAndAddEntry(k, v)
|
||||
}
|
||||
} else {
|
||||
entry = c.makeAndAddEntry(k, v)
|
||||
}
|
||||
|
||||
entry.changeState(ready)
|
||||
}
|
||||
|
||||
// makeAndAddEntry is a helper function to create and add a new
|
||||
// entry to the cache map and evict older entry as needed.
|
||||
func (c *linkAddrCache) makeAndAddEntry(k tcpip.FullAddress, v tcpip.LinkAddress) *linkAddrEntry {
|
||||
// Take over the next entry.
|
||||
entry := &c.entries[c.next]
|
||||
if c.cache[entry.addr] == entry {
|
||||
delete(c.cache, entry.addr)
|
||||
}
|
||||
|
||||
// Mark the soon-to-be-replaced entry as expired, just in case there is
|
||||
// someone waiting for address resolution on it.
|
||||
entry.changeState(expired)
|
||||
|
||||
*entry = linkAddrEntry{
|
||||
addr: k,
|
||||
linkAddr: v,
|
||||
expiration: time.Now().Add(c.ageLimit),
|
||||
wakers: make(map[*sleep.Waker]struct{}),
|
||||
done: make(chan struct{}),
|
||||
}
|
||||
|
||||
c.cache[k] = entry
|
||||
c.next = (c.next + 1) % len(c.entries)
|
||||
return entry
|
||||
}
|
||||
|
||||
// get reports any known link address for k.
|
||||
func (c *linkAddrCache) get(k tcpip.FullAddress, linkRes LinkAddressResolver, localAddr tcpip.Address, linkEP LinkEndpoint, waker *sleep.Waker) (tcpip.LinkAddress, <-chan struct{}, *tcpip.Error) {
|
||||
log.Printf("link addr get linkRes: %#v, addr: %+v", linkRes, k)
|
||||
if linkRes != nil {
|
||||
if addr, ok := linkRes.ResolveStaticAddress(k.Addr); ok {
|
||||
return addr, nil, nil
|
||||
}
|
||||
}
|
||||
|
||||
c.mu.Lock()
|
||||
defer c.mu.Unlock()
|
||||
// 尝试从缓存中得到MAC地址
|
||||
if entry, ok := c.cache[k]; ok {
|
||||
switch s := entry.state(); s {
|
||||
case expired:
|
||||
case ready:
|
||||
return entry.linkAddr, nil, nil
|
||||
case failed:
|
||||
return "", nil, tcpip.ErrNoLinkAddress
|
||||
case incomplete:
|
||||
// Address resolution is still in progress.
|
||||
entry.addWaker(waker)
|
||||
return "", entry.done, tcpip.ErrWouldBlock
|
||||
default:
|
||||
panic(fmt.Sprintf("invalid cache entry state: %s", s))
|
||||
}
|
||||
}
|
||||
|
||||
if linkRes == nil {
|
||||
return "", nil, tcpip.ErrNoLinkAddress
|
||||
}
|
||||
|
||||
// Add 'incomplete' entry in the cache to mark that resolution is in progress.
|
||||
e := c.makeAndAddEntry(k, "")
|
||||
e.addWaker(waker)
|
||||
|
||||
go c.startAddressResolution(k, linkRes, localAddr, linkEP, e.done)
|
||||
|
||||
return "", e.done, tcpip.ErrWouldBlock
|
||||
}
|
||||
|
||||
// removeWaker removes a waker previously added through get().
|
||||
func (c *linkAddrCache) removeWaker(k tcpip.FullAddress, waker *sleep.Waker) {
|
||||
c.mu.Lock()
|
||||
defer c.mu.Unlock()
|
||||
|
||||
if entry, ok := c.cache[k]; ok {
|
||||
entry.removeWaker(waker)
|
||||
}
|
||||
}
|
||||
|
||||
func (c *linkAddrCache) startAddressResolution(k tcpip.FullAddress, linkRes LinkAddressResolver, localAddr tcpip.Address, linkEP LinkEndpoint, done <-chan struct{}) {
|
||||
for i := 0; ; i++ {
|
||||
// Send link request, then wait for the timeout limit and check
|
||||
// whether the request succeeded.
|
||||
linkRes.LinkAddressRequest(k.Addr, localAddr, linkEP)
|
||||
|
||||
select {
|
||||
case <-time.After(c.resolutionTimeout):
|
||||
if stop := c.checkLinkRequest(k, i); stop {
|
||||
return
|
||||
}
|
||||
case <-done:
|
||||
return
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
// checkLinkRequest checks whether previous attempt to resolve address has succeeded
|
||||
// and mark the entry accordingly, e.g. ready, failed, etc. Return true if request
|
||||
// can stop, false if another request should be sent.
|
||||
func (c *linkAddrCache) checkLinkRequest(k tcpip.FullAddress, attempt int) bool {
|
||||
c.mu.Lock()
|
||||
defer c.mu.Unlock()
|
||||
|
||||
entry, ok := c.cache[k]
|
||||
if !ok {
|
||||
// Entry was evicted from the cache.
|
||||
return true
|
||||
}
|
||||
|
||||
switch s := entry.state(); s {
|
||||
case ready, failed, expired:
|
||||
// Entry was made ready by resolver or failed. Either way we're done.
|
||||
return true
|
||||
case incomplete:
|
||||
if attempt+1 >= c.resolutionAttempts {
|
||||
// Max number of retries reached, mark entry as failed.
|
||||
entry.changeState(failed)
|
||||
return true
|
||||
}
|
||||
// No response yet, need to send another ARP request.
|
||||
return false
|
||||
default:
|
||||
panic(fmt.Sprintf("invalid cache entry state: %s", s))
|
||||
}
|
||||
}
|
||||
|
||||
func newLinkAddrCache(ageLimit, resolutionTimeout time.Duration, resolutionAttempts int) *linkAddrCache {
|
||||
return &linkAddrCache{
|
||||
ageLimit: ageLimit,
|
||||
resolutionTimeout: resolutionTimeout,
|
||||
resolutionAttempts: resolutionAttempts,
|
||||
cache: make(map[tcpip.FullAddress]*linkAddrEntry, linkAddrCacheSize),
|
||||
}
|
||||
}
|
||||
|
||||
Reference in New Issue
Block a user