/
safe_search.go
149 lines (127 loc) · 3.63 KB
/
safe_search.go
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package dnsfilter
import (
"bytes"
"encoding/binary"
"encoding/gob"
"encoding/json"
"fmt"
"net"
"net/http"
"time"
"github.com/AdguardTeam/golibs/cache"
"github.com/AdguardTeam/golibs/log"
)
/*
expire byte[4]
res Result
*/
func (d *Dnsfilter) setCacheResult(cache cache.Cache, host string, res Result) int {
var buf bytes.Buffer
expire := uint(time.Now().Unix()) + d.Config.CacheTime*60
var exp []byte
exp = make([]byte, 4)
binary.BigEndian.PutUint32(exp, uint32(expire))
_, _ = buf.Write(exp)
enc := gob.NewEncoder(&buf)
err := enc.Encode(res)
if err != nil {
log.Error("gob.Encode(): %s", err)
return 0
}
val := buf.Bytes()
_ = cache.Set([]byte(host), val)
return len(val)
}
func getCachedResult(cache cache.Cache, host string) (Result, bool) {
data := cache.Get([]byte(host))
if data == nil {
return Result{}, false
}
exp := int(binary.BigEndian.Uint32(data[:4]))
if exp <= int(time.Now().Unix()) {
cache.Del([]byte(host))
return Result{}, false
}
var buf bytes.Buffer
buf.Write(data[4:])
dec := gob.NewDecoder(&buf)
r := Result{}
err := dec.Decode(&r)
if err != nil {
log.Debug("gob.Decode(): %s", err)
return Result{}, false
}
return r, true
}
// SafeSearchDomain returns replacement address for search engine
func (d *Dnsfilter) SafeSearchDomain(host string) (string, bool) {
val, ok := safeSearchDomains[host]
return val, ok
}
func (d *Dnsfilter) checkSafeSearch(host string) (Result, error) {
if log.GetLevel() >= log.DEBUG {
timer := log.StartTimer()
defer timer.LogElapsed("SafeSearch: lookup for %s", host)
}
// Check cache. Return cached result if it was found
cachedValue, isFound := getCachedResult(gctx.safeSearchCache, host)
if isFound {
// atomic.AddUint64(&gctx.stats.Safesearch.CacheHits, 1)
log.Tracef("SafeSearch: found in cache: %s", host)
return cachedValue, nil
}
safeHost, ok := d.SafeSearchDomain(host)
if !ok {
return Result{}, nil
}
res := Result{IsFiltered: true, Reason: FilteredSafeSearch}
if ip := net.ParseIP(safeHost); ip != nil {
res.IP = ip
valLen := d.setCacheResult(gctx.safeSearchCache, host, res)
log.Debug("SafeSearch: stored in cache: %s (%d bytes)", host, valLen)
return res, nil
}
// TODO this address should be resolved with upstream that was configured in dnsforward
addrs, err := net.LookupIP(safeHost)
if err != nil {
log.Tracef("SafeSearchDomain for %s was found but failed to lookup for %s cause %s", host, safeHost, err)
return Result{}, err
}
for _, i := range addrs {
if ipv4 := i.To4(); ipv4 != nil {
res.IP = ipv4
break
}
}
if len(res.IP) == 0 {
return Result{}, fmt.Errorf("no ipv4 addresses in safe search response for %s", safeHost)
}
// Cache result
valLen := d.setCacheResult(gctx.safeSearchCache, host, res)
log.Debug("SafeSearch: stored in cache: %s (%d bytes)", host, valLen)
return res, nil
}
func (d *Dnsfilter) handleSafeSearchEnable(w http.ResponseWriter, r *http.Request) {
d.Config.SafeSearchEnabled = true
d.Config.ConfigModified()
}
func (d *Dnsfilter) handleSafeSearchDisable(w http.ResponseWriter, r *http.Request) {
d.Config.SafeSearchEnabled = false
d.Config.ConfigModified()
}
func (d *Dnsfilter) handleSafeSearchStatus(w http.ResponseWriter, r *http.Request) {
data := map[string]interface{}{
"enabled": d.Config.SafeSearchEnabled,
}
jsonVal, err := json.Marshal(data)
if err != nil {
httpError(r, w, http.StatusInternalServerError, "Unable to marshal status json: %s", err)
return
}
w.Header().Set("Content-Type", "application/json")
_, err = w.Write(jsonVal)
if err != nil {
httpError(r, w, http.StatusInternalServerError, "Unable to write response json: %s", err)
return
}
}