badguardhome/filter.go

365 lines
8.9 KiB
Go

package main
import (
"fmt"
"hash/crc32"
"io/ioutil"
"os"
"path/filepath"
"regexp"
"strconv"
"strings"
"time"
"github.com/AdguardTeam/AdGuardHome/dnsfilter"
"github.com/AdguardTeam/golibs/file"
"github.com/AdguardTeam/golibs/log"
)
var (
nextFilterID = time.Now().Unix() // semi-stable way to generate an unique ID
filterTitleRegexp = regexp.MustCompile(`^! Title: +(.*)$`)
)
// field ordering is important -- yaml fields will mirror ordering from here
type filter struct {
Enabled bool `json:"enabled"`
URL string `json:"url"`
Name string `json:"name" yaml:"name"`
RulesCount int `json:"rulesCount" yaml:"-"`
LastUpdated time.Time `json:"lastUpdated,omitempty" yaml:"-"`
checksum uint32 // checksum of the file data
dnsfilter.Filter `yaml:",inline"`
}
// Creates a helper object for working with the user rules
func userFilter() filter {
return filter{
// User filter always has constant ID=0
Enabled: true,
Filter: dnsfilter.Filter{
Rules: config.UserRules,
},
}
}
// Enable or disable a filter
func filterEnable(url string, enable bool) bool {
r := false
config.Lock()
for i := range config.Filters {
filter := &config.Filters[i] // otherwise we will be operating on a copy
if filter.URL == url {
filter.Enabled = enable
if enable {
e := filter.load()
if e != nil {
// This isn't a fatal error,
// because it may occur when someone removes the file from disk.
// In this case the periodic update task will try to download the file.
filter.LastUpdated = time.Time{}
log.Tracef("%s filter load: %v", url, e)
}
} else {
filter.unload()
}
r = true
break
}
}
config.Unlock()
return r
}
// Return TRUE if a filter with this URL exists
func filterExists(url string) bool {
r := false
config.RLock()
for i := range config.Filters {
if config.Filters[i].URL == url {
r = true
break
}
}
config.RUnlock()
return r
}
// Add a filter
// Return FALSE if a filter with this URL exists
func filterAdd(f filter) bool {
config.Lock()
// Check for duplicates
for i := range config.Filters {
if config.Filters[i].URL == f.URL {
config.Unlock()
return false
}
}
config.Filters = append(config.Filters, f)
config.Unlock()
return true
}
// Load filters from the disk
// And if any filter has zero ID, assign a new one
func loadFilters() {
for i := range config.Filters {
filter := &config.Filters[i] // otherwise we're operating on a copy
if filter.ID == 0 {
filter.ID = assignUniqueFilterID()
}
if !filter.Enabled {
// No need to load a filter that is not enabled
continue
}
err := filter.load()
if err != nil {
// This is okay for the first start, the filter will be loaded later
log.Debug("Couldn't load filter %d contents due to %s", filter.ID, err)
}
}
}
func deduplicateFilters() {
// Deduplicate filters
i := 0 // output index, used for deletion later
urls := map[string]bool{}
for _, filter := range config.Filters {
if _, ok := urls[filter.URL]; !ok {
// we didn't see it before, keep it
urls[filter.URL] = true // remember the URL
config.Filters[i] = filter
i++
}
}
// all entries we want to keep are at front, delete the rest
config.Filters = config.Filters[:i]
}
// Set the next filter ID to max(filter.ID) + 1
func updateUniqueFilterID(filters []filter) {
for _, filter := range filters {
if nextFilterID < filter.ID {
nextFilterID = filter.ID + 1
}
}
}
func assignUniqueFilterID() int64 {
value := nextFilterID
nextFilterID++
return value
}
// Sets up a timer that will be checking for filters updates periodically
func periodicallyRefreshFilters() {
for range time.Tick(time.Minute) {
refreshFiltersIfNecessary(false)
}
}
// Checks filters updates if necessary
// If force is true, it ignores the filter.LastUpdated field value
func refreshFiltersIfNecessary(force bool) int {
config.Lock()
// fetch URLs
updateCount := 0
for i := range config.Filters {
filter := &config.Filters[i] // otherwise we will be operating on a copy
if !filter.Enabled {
continue
}
if !force && time.Since(filter.LastUpdated) <= updatePeriod {
continue
}
updated, err := filter.update()
if err != nil {
log.Printf("Failed to update filter %s: %s\n", filter.URL, err)
continue
}
if updated {
// Saving it to the filters dir now
err = filter.save()
if err != nil {
log.Printf("Failed to save the updated filter %d: %s", filter.ID, err)
continue
}
updateCount++
} else {
mtime := time.Now()
os.Chtimes(filter.Path(), mtime, mtime)
filter.LastUpdated = mtime
}
}
config.Unlock()
if updateCount > 0 && isRunning() {
err := reconfigureDNSServer()
if err != nil {
msg := fmt.Sprintf("SHOULD NOT HAPPEN: cannot reconfigure DNS server with the new filters: %s", err)
panic(msg)
}
}
return updateCount
}
// A helper function that parses filter contents and returns a number of rules and a filter name (if there's any)
func parseFilterContents(contents []byte) (int, string, []string) {
lines := strings.Split(string(contents), "\n")
rulesCount := 0
name := ""
seenTitle := false
// Count lines in the filter
for _, line := range lines {
line = strings.TrimSpace(line)
if len(line) == 0 {
continue
}
if line[0] == '!' {
m := filterTitleRegexp.FindAllStringSubmatch(line, -1)
if len(m) > 0 && len(m[0]) >= 2 && !seenTitle {
name = m[0][1]
seenTitle = true
}
} else {
rulesCount++
}
}
return rulesCount, name, lines
}
// Perform upgrade on a filter
func (filter *filter) update() (bool, error) {
log.Tracef("Downloading update for filter %d from %s", filter.ID, filter.URL)
resp, err := client.Get(filter.URL)
if resp != nil && resp.Body != nil {
defer resp.Body.Close()
}
if err != nil {
log.Printf("Couldn't request filter from URL %s, skipping: %s", filter.URL, err)
return false, err
}
if resp.StatusCode != 200 {
log.Printf("Got status code %d from URL %s, skipping", resp.StatusCode, filter.URL)
return false, fmt.Errorf("got status code != 200: %d", resp.StatusCode)
}
contentType := strings.ToLower(resp.Header.Get("content-type"))
if !strings.HasPrefix(contentType, "text/plain") {
log.Printf("Non-text response %s from %s, skipping", contentType, filter.URL)
return false, fmt.Errorf("non-text response %s", contentType)
}
body, err := ioutil.ReadAll(resp.Body)
if err != nil {
log.Printf("Couldn't fetch filter contents from URL %s, skipping: %s", filter.URL, err)
return false, err
}
// Check if the filter has been really changed
checksum := crc32.ChecksumIEEE(body)
if filter.checksum == checksum {
log.Tracef("Filter #%d at URL %s hasn't changed, not updating it", filter.ID, filter.URL)
return false, nil
}
// Extract filter name and count number of rules
rulesCount, filterName, rules := parseFilterContents(body)
log.Printf("Filter %d has been updated: %d bytes, %d rules", filter.ID, len(body), rulesCount)
if filterName != "" {
filter.Name = filterName
}
filter.RulesCount = rulesCount
filter.Rules = rules
filter.checksum = checksum
return true, nil
}
// saves filter contents to the file in dataDir
func (filter *filter) save() error {
filterFilePath := filter.Path()
log.Printf("Saving filter %d contents to: %s", filter.ID, filterFilePath)
body := []byte(strings.Join(filter.Rules, "\n"))
err := file.SafeWrite(filterFilePath, body)
// update LastUpdated field after saving the file
filter.LastUpdated = filter.LastTimeUpdated()
return err
}
// loads filter contents from the file in dataDir
func (filter *filter) load() error {
filterFilePath := filter.Path()
log.Tracef("Loading filter %d contents to: %s", filter.ID, filterFilePath)
if _, err := os.Stat(filterFilePath); os.IsNotExist(err) {
// do nothing, file doesn't exist
return err
}
filterFileContents, err := ioutil.ReadFile(filterFilePath)
if err != nil {
return err
}
log.Tracef("File %s, id %d, length %d", filterFilePath, filter.ID, len(filterFileContents))
rulesCount, _, rules := parseFilterContents(filterFileContents)
filter.RulesCount = rulesCount
filter.Rules = rules
filter.checksum = crc32.ChecksumIEEE(filterFileContents)
filter.LastUpdated = filter.LastTimeUpdated()
return nil
}
// Clear filter rules
func (filter *filter) unload() {
filter.Rules = []string{}
filter.RulesCount = 0
}
// Path to the filter contents
func (filter *filter) Path() string {
return filepath.Join(config.ourWorkingDir, dataDir, filterDir, strconv.FormatInt(filter.ID, 10)+".txt")
}
// LastTimeUpdated returns the time when the filter was last time updated
func (filter *filter) LastTimeUpdated() time.Time {
filterFilePath := filter.Path()
s, err := os.Stat(filterFilePath)
if os.IsNotExist(err) {
// if the filter file does not exist, return 0001-01-01
return time.Time{}
}
if err != nil {
// if the filter file does not exist, return 0001-01-01
return time.Time{}
}
// filter file modified time
return s.ModTime()
}