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Merge pull request #404 from weaveworks/scope-364
reverse resolutions for remote side of connections.
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,76 @@ | ||
| package endpoint | ||
|
|
||
| import ( | ||
| "net" | ||
| "strings" | ||
| "time" | ||
|
|
||
| "github.com/bluele/gcache" | ||
| ) | ||
|
|
||
| const ( | ||
| rAddrCacheLen = 500 // Default cache length | ||
| rAddrBacklog = 1000 | ||
| rAddrCacheExpiration = 30 * time.Minute | ||
| ) | ||
|
|
||
| type revResFunc func(addr string) (names []string, err error) | ||
|
|
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| // ReverseResolver is a caching, reverse resolver. | ||
| type ReverseResolver struct { | ||
| addresses chan string | ||
| cache gcache.Cache | ||
| Throttle <-chan time.Time // Made public for mocking | ||
| Resolver revResFunc | ||
| } | ||
|
|
||
| // NewReverseResolver starts a new reverse resolver that performs reverse | ||
| // resolutions and caches the result. | ||
| func NewReverseResolver() *ReverseResolver { | ||
| r := ReverseResolver{ | ||
| addresses: make(chan string, rAddrBacklog), | ||
| cache: gcache.New(rAddrCacheLen).LRU().Expiration(rAddrCacheExpiration).Build(), | ||
| Throttle: time.Tick(time.Second / 10), | ||
| Resolver: net.LookupAddr, | ||
| } | ||
| go r.loop() | ||
| return &r | ||
| } | ||
|
|
||
| // Get the reverse resolution for an IP address if already in the cache, a | ||
| // gcache.NotFoundKeyError error otherwise. Note: it returns one of the | ||
| // possible names that can be obtained for that IP. | ||
| func (r *ReverseResolver) Get(address string) (string, error) { | ||
| val, err := r.cache.Get(address) | ||
| if err == nil { | ||
| return val.(string), nil | ||
| } | ||
| if err == gcache.NotFoundKeyError { | ||
| // We trigger a asynchronous reverse resolution when not cached | ||
| select { | ||
| case r.addresses <- address: | ||
| default: | ||
| } | ||
| } | ||
| return "", err | ||
| } | ||
|
|
||
| func (r *ReverseResolver) loop() { | ||
| for request := range r.addresses { | ||
| <-r.Throttle // rate limit our DNS resolutions | ||
| // and check if the answer is already in the cache | ||
| if _, err := r.cache.Get(request); err == nil { | ||
| continue | ||
| } | ||
| names, err := r.Resolver(request) | ||
| if err == nil && len(names) > 0 { | ||
| name := strings.TrimRight(names[0], ".") | ||
| r.cache.Set(request, name) | ||
| } | ||
| } | ||
| } | ||
|
|
||
| // Stop the async reverse resolver. | ||
| func (r *ReverseResolver) Stop() { | ||
| close(r.addresses) | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,38 @@ | ||
| package endpoint_test | ||
|
|
||
| import ( | ||
| "errors" | ||
| "testing" | ||
| "time" | ||
|
|
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| . "github.com/weaveworks/scope/probe/endpoint" | ||
| "github.com/weaveworks/scope/test" | ||
| ) | ||
|
|
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| func TestReverseResolver(t *testing.T) { | ||
| tests := map[string]string{ | ||
| "1.2.3.4": "test.domain.name", | ||
| "4.3.2.1": "im.a.little.tea.pot", | ||
| } | ||
|
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| revRes := NewReverseResolver() | ||
| defer revRes.Stop() | ||
|
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| // Use a mocked resolver function. | ||
| revRes.Resolver = func(addr string) (names []string, err error) { | ||
| if name, ok := tests[addr]; ok { | ||
| return []string{name}, nil | ||
| } | ||
| return []string{}, errors.New("invalid IP") | ||
| } | ||
|
|
||
| // Up the rate limit so the test runs faster. | ||
| revRes.Throttle = time.Tick(time.Millisecond) | ||
|
|
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| for ip, hostname := range tests { | ||
| test.Poll(t, 100*time.Millisecond, hostname, func() interface{} { | ||
| result, _ := revRes.Get(ip) | ||
| return result | ||
| }) | ||
| } | ||
| } |
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