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answercache.go
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answercache.go
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package wildcarder
import (
"sync"
)
type answerCache struct {
cache map[AnswerHash][]string
mu sync.Mutex
}
func newAnswerCache() *answerCache {
cache := answerCache{}
cache.cache = make(map[AnswerHash][]string)
return &cache
}
// add adds DNS answers to the list and associate a root domain to them.
func (c *answerCache) add(root string, answers []DNSAnswer) {
c.mu.Lock()
answerHashes := []AnswerHash{}
for _, answer := range answers {
answerHashes = append(answerHashes, HashAnswer(answer))
}
c.mu.Unlock()
c.addHash(root, answerHashes)
}
// addHash adds DNS answer hashes to the list and associate a root domain to them.
func (c *answerCache) addHash(root string, answers []AnswerHash) {
c.mu.Lock()
defer c.mu.Unlock()
for _, answer := range answers {
if _, ok := c.cache[answer]; !ok {
c.cache[answer] = []string{}
}
found := false
for _, r := range c.cache[answer] {
if root == r {
found = true
break
}
}
if !found {
c.cache[answer] = append(c.cache[answer], root)
}
}
}
// find returns the root domains associated with DNS answers.
func (c *answerCache) find(answers []DNSAnswer) []string {
c.mu.Lock()
answerHashes := []AnswerHash{}
for _, answer := range answers {
answerHashes = append(answerHashes, HashAnswer(answer))
}
c.mu.Unlock()
return c.findHash(answerHashes)
}
// findHash returns the root domains associated with DNS answer hashes.
func (c *answerCache) findHash(answers []AnswerHash) []string {
c.mu.Lock()
defer c.mu.Unlock()
for _, answer := range answers {
if roots, ok := c.cache[answer]; ok {
return roots
}
}
return []string{}
}
// count returns the number of answers in the cache.
func (c *answerCache) count() int {
var count int
for _, answers := range c.cache {
count += len(answers)
}
return count
}