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filter.go
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filter.go
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package home
import (
"bufio"
"fmt"
"hash/crc32"
"io"
"net/http"
"os"
"path/filepath"
"regexp"
"strconv"
"strings"
"sync"
"sync/atomic"
"time"
"github.com/AdguardTeam/AdGuardHome/internal/filtering"
"github.com/AdguardTeam/golibs/errors"
"github.com/AdguardTeam/golibs/log"
"github.com/AdguardTeam/golibs/stringutil"
)
var nextFilterID = time.Now().Unix() // semi-stable way to generate an unique ID
// Filtering - module object
type Filtering struct {
// conf FilteringConf
refreshStatus uint32 // 0:none; 1:in progress
refreshLock sync.Mutex
filterTitleRegexp *regexp.Regexp
}
// Init - initialize the module
func (f *Filtering) Init() {
f.filterTitleRegexp = regexp.MustCompile(`^! Title: +(.*)$`)
_ = os.MkdirAll(filepath.Join(Context.getDataDir(), filterDir), 0o755)
f.loadFilters(config.Filters)
f.loadFilters(config.WhitelistFilters)
deduplicateFilters()
updateUniqueFilterID(config.Filters)
updateUniqueFilterID(config.WhitelistFilters)
}
// Start - start the module
func (f *Filtering) Start() {
f.RegisterFilteringHandlers()
// Here we should start updating filters,
// but currently we can't wake up the periodic task to do so.
// So for now we just start this periodic task from here.
go f.periodicallyRefreshFilters()
}
// Close - close the module
func (f *Filtering) Close() {
}
func defaultFilters() []filter {
return []filter{
{Filter: filtering.Filter{ID: 1}, Enabled: true, URL: "https://adguardteam.github.io/AdGuardSDNSFilter/Filters/filter.txt", Name: "AdGuard DNS filter"},
{Filter: filtering.Filter{ID: 2}, Enabled: false, URL: "https://adaway.org/hosts.txt", Name: "AdAway Default Blocklist"},
}
}
// field ordering is important -- yaml fields will mirror ordering from here
type filter struct {
Enabled bool
URL string // URL or a file path
Name string `yaml:"name"`
RulesCount int `yaml:"-"`
LastUpdated time.Time `yaml:"-"`
checksum uint32 // checksum of the file data
white bool
filtering.Filter `yaml:",inline"`
}
const (
statusFound = 1
statusEnabledChanged = 2
statusURLChanged = 4
statusURLExists = 8
statusUpdateRequired = 0x10
)
// Update properties for a filter specified by its URL
// Return status* flags.
func (f *Filtering) filterSetProperties(url string, newf filter, whitelist bool) int {
r := 0
config.Lock()
defer config.Unlock()
filters := &config.Filters
if whitelist {
filters = &config.WhitelistFilters
}
for i := range *filters {
filt := &(*filters)[i]
if filt.URL != url {
continue
}
log.Debug("filter: set properties: %s: {%s %s %v}",
filt.URL, newf.Name, newf.URL, newf.Enabled)
filt.Name = newf.Name
if filt.URL != newf.URL {
r |= statusURLChanged | statusUpdateRequired
if filterExistsNoLock(newf.URL) {
return statusURLExists
}
filt.URL = newf.URL
filt.unload()
filt.LastUpdated = time.Time{}
filt.checksum = 0
filt.RulesCount = 0
}
if filt.Enabled != newf.Enabled {
r |= statusEnabledChanged
filt.Enabled = newf.Enabled
if filt.Enabled {
if (r & statusURLChanged) == 0 {
e := f.load(filt)
if e != nil {
// This isn't a fatal error,
// because it may occur when someone removes the file from disk.
filt.LastUpdated = time.Time{}
filt.checksum = 0
filt.RulesCount = 0
r |= statusUpdateRequired
}
}
} else {
filt.unload()
}
}
return r | statusFound
}
return 0
}
// Return TRUE if a filter with this URL exists
func filterExists(url string) bool {
config.RLock()
r := filterExistsNoLock(url)
config.RUnlock()
return r
}
func filterExistsNoLock(url string) bool {
for _, f := range config.Filters {
if f.URL == url {
return true
}
}
for _, f := range config.WhitelistFilters {
if f.URL == url {
return true
}
}
return false
}
// Add a filter
// Return FALSE if a filter with this URL exists
func filterAdd(f filter) bool {
config.Lock()
defer config.Unlock()
// Check for duplicates
if filterExistsNoLock(f.URL) {
return false
}
if f.white {
config.WhitelistFilters = append(config.WhitelistFilters, f)
} else {
config.Filters = append(config.Filters, f)
}
return true
}
// Load filters from the disk
// And if any filter has zero ID, assign a new one
func (f *Filtering) loadFilters(array []filter) {
for i := range array {
filter := &array[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 := f.load(filter)
if err != nil {
log.Error("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 (f *Filtering) periodicallyRefreshFilters() {
const maxInterval = 1 * 60 * 60
intval := 5 // use a dynamically increasing time interval
for {
isNetworkErr := false
if config.DNS.FiltersUpdateIntervalHours != 0 && atomic.CompareAndSwapUint32(&f.refreshStatus, 0, 1) {
f.refreshLock.Lock()
_, isNetworkErr = f.refreshFiltersIfNecessary(filterRefreshBlocklists | filterRefreshAllowlists)
f.refreshLock.Unlock()
f.refreshStatus = 0
if !isNetworkErr {
intval = maxInterval
}
}
if isNetworkErr {
intval *= 2
if intval > maxInterval {
intval = maxInterval
}
}
time.Sleep(time.Duration(intval) * time.Second)
}
}
// Refresh filters
// flags: filterRefresh*
// important:
// TRUE: ignore the fact that we're currently updating the filters
func (f *Filtering) refreshFilters(flags int, important bool) (int, error) {
set := atomic.CompareAndSwapUint32(&f.refreshStatus, 0, 1)
if !important && !set {
return 0, fmt.Errorf("filters update procedure is already running")
}
f.refreshLock.Lock()
nUpdated, _ := f.refreshFiltersIfNecessary(flags)
f.refreshLock.Unlock()
f.refreshStatus = 0
return nUpdated, nil
}
func (f *Filtering) refreshFiltersArray(filters *[]filter, force bool) (int, []filter, []bool, bool) {
var updateFilters []filter
var updateFlags []bool // 'true' if filter data has changed
now := time.Now()
config.RLock()
for i := range *filters {
f := &(*filters)[i] // otherwise we will be operating on a copy
if !f.Enabled {
continue
}
expireTime := f.LastUpdated.Unix() + int64(config.DNS.FiltersUpdateIntervalHours)*60*60
if !force && expireTime > now.Unix() {
continue
}
var uf filter
uf.ID = f.ID
uf.URL = f.URL
uf.Name = f.Name
uf.checksum = f.checksum
updateFilters = append(updateFilters, uf)
}
config.RUnlock()
if len(updateFilters) == 0 {
return 0, nil, nil, false
}
nfail := 0
for i := range updateFilters {
uf := &updateFilters[i]
updated, err := f.update(uf)
updateFlags = append(updateFlags, updated)
if err != nil {
nfail++
log.Printf("Failed to update filter %s: %s\n", uf.URL, err)
continue
}
}
if nfail == len(updateFilters) {
return 0, nil, nil, true
}
updateCount := 0
for i := range updateFilters {
uf := &updateFilters[i]
updated := updateFlags[i]
config.Lock()
for k := range *filters {
f := &(*filters)[k]
if f.ID != uf.ID || f.URL != uf.URL {
continue
}
f.LastUpdated = uf.LastUpdated
if !updated {
continue
}
log.Info("Updated filter #%d. Rules: %d -> %d",
f.ID, f.RulesCount, uf.RulesCount)
f.Name = uf.Name
f.RulesCount = uf.RulesCount
f.checksum = uf.checksum
updateCount++
}
config.Unlock()
}
return updateCount, updateFilters, updateFlags, false
}
const (
filterRefreshForce = 1 // ignore last file modification date
filterRefreshAllowlists = 2 // update allow-lists
filterRefreshBlocklists = 4 // update block-lists
)
// Checks filters updates if necessary
// If force is true, it ignores the filter.LastUpdated field value
// flags: filterRefresh*
//
// Algorithm:
// . Get the list of filters to be updated
// . For each filter run the download and checksum check operation
// . Store downloaded data in a temporary file inside data/filters directory
// . For each filter:
// . If filter data hasn't changed, just set new update time on file
// . If filter data has changed:
// . rename the temporary file (<temp> -> 1.txt)
// Note that this method works only on UNIX.
// On Windows we don't pass files to filtering - we pass the whole data.
// . Pass new filters to filtering object - it analyzes new data while the old filters are still active
// . filtering activates new filters
//
// Return the number of updated filters
// Return TRUE - there was a network error and nothing could be updated
func (f *Filtering) refreshFiltersIfNecessary(flags int) (int, bool) {
log.Debug("Filters: updating...")
updateCount := 0
var updateFilters []filter
var updateFlags []bool
netError := false
netErrorW := false
force := false
if (flags & filterRefreshForce) != 0 {
force = true
}
if (flags & filterRefreshBlocklists) != 0 {
updateCount, updateFilters, updateFlags, netError = f.refreshFiltersArray(&config.Filters, force)
}
if (flags & filterRefreshAllowlists) != 0 {
updateCountW := 0
var updateFiltersW []filter
var updateFlagsW []bool
updateCountW, updateFiltersW, updateFlagsW, netErrorW = f.refreshFiltersArray(&config.WhitelistFilters, force)
updateCount += updateCountW
updateFilters = append(updateFilters, updateFiltersW...)
updateFlags = append(updateFlags, updateFlagsW...)
}
if netError && netErrorW {
return 0, true
}
if updateCount != 0 {
enableFilters(false)
for i := range updateFilters {
uf := &updateFilters[i]
updated := updateFlags[i]
if !updated {
continue
}
_ = os.Remove(uf.Path() + ".old")
}
}
log.Debug("Filters: update finished")
return updateCount, false
}
// Allows printable UTF-8 text with CR, LF, TAB characters
func isPrintableText(data []byte, len int) bool {
for i := 0; i < len; i++ {
c := data[i]
if (c >= ' ' && c != 0x7f) || c == '\n' || c == '\r' || c == '\t' {
continue
}
return false
}
return true
}
// A helper function that parses filter contents and returns a number of rules and a filter name (if there's any)
func (f *Filtering) parseFilterContents(file io.Reader) (int, uint32, string) {
rulesCount := 0
name := ""
seenTitle := false
r := bufio.NewReader(file)
checksum := uint32(0)
for {
line, err := r.ReadString('\n')
checksum = crc32.Update(checksum, crc32.IEEETable, []byte(line))
line = strings.TrimSpace(line)
if len(line) == 0 {
//
} else if line[0] == '!' {
m := f.filterTitleRegexp.FindAllStringSubmatch(line, -1)
if len(m) > 0 && len(m[0]) >= 2 && !seenTitle {
name = m[0][1]
seenTitle = true
}
} else if line[0] == '#' {
//
} else {
rulesCount++
}
if err != nil {
break
}
}
return rulesCount, checksum, name
}
// Perform upgrade on a filter and update LastUpdated value
func (f *Filtering) update(filter *filter) (bool, error) {
b, err := f.updateIntl(filter)
filter.LastUpdated = time.Now()
if !b {
e := os.Chtimes(filter.Path(), filter.LastUpdated, filter.LastUpdated)
if e != nil {
log.Error("os.Chtimes(): %v", e)
}
}
return b, err
}
func (f *Filtering) read(reader io.Reader, tmpFile *os.File, filter *filter) (int, error) {
htmlTest := true
firstChunk := make([]byte, 4*1024)
firstChunkLen := 0
buf := make([]byte, 64*1024)
total := 0
for {
n, err := reader.Read(buf)
total += n
if htmlTest {
num := len(firstChunk) - firstChunkLen
if n < num {
num = n
}
copied := copy(firstChunk[firstChunkLen:], buf[:num])
firstChunkLen += copied
if firstChunkLen == len(firstChunk) || err == io.EOF {
if !isPrintableText(firstChunk, firstChunkLen) {
return total, fmt.Errorf("data contains non-printable characters")
}
s := strings.ToLower(string(firstChunk))
if strings.Contains(s, "<html") || strings.Contains(s, "<!doctype") {
return total, fmt.Errorf("data is HTML, not plain text")
}
htmlTest = false
firstChunk = nil
}
}
_, err2 := tmpFile.Write(buf[:n])
if err2 != nil {
return total, err2
}
if err == io.EOF {
return total, nil
}
if err != nil {
log.Printf("Couldn't fetch filter contents from URL %s, skipping: %s", filter.URL, err)
return total, err
}
}
}
// finalizeUpdate closes and gets rid of temporary file f with filter's content
// according to updated. It also saves new values of flt's name, rules number
// and checksum if sucсeeded.
func finalizeUpdate(
f *os.File,
flt *filter,
updated bool,
name string,
rnum int,
cs uint32,
) (err error) {
tmpFileName := f.Name()
// Close the file before renaming it because it's required on Windows.
//
// See https://github.com/adguardTeam/adGuardHome/issues/1553.
if err = f.Close(); err != nil {
return fmt.Errorf("closing temporary file: %w", err)
}
if !updated {
log.Tracef("filter #%d from %s has no changes, skip", flt.ID, flt.URL)
return os.Remove(tmpFileName)
}
log.Printf("saving filter %d contents to: %s", flt.ID, flt.Path())
if err = os.Rename(tmpFileName, flt.Path()); err != nil {
return errors.WithDeferred(err, os.Remove(tmpFileName))
}
flt.Name = stringutil.Coalesce(flt.Name, name)
flt.checksum = cs
flt.RulesCount = rnum
return nil
}
// processUpdate copies filter's content from src to dst and returns the name,
// rules number, and checksum for it. It also returns the number of bytes read
// from src.
func (f *Filtering) processUpdate(
src io.Reader,
dst *os.File,
flt *filter,
) (name string, rnum int, cs uint32, n int, err error) {
if n, err = f.read(src, dst, flt); err != nil {
return "", 0, 0, 0, err
}
if _, err = dst.Seek(0, io.SeekStart); err != nil {
return "", 0, 0, 0, err
}
rnum, cs, name = f.parseFilterContents(dst)
return name, rnum, cs, n, nil
}
// updateIntl updates the flt rewriting it's actual file. It returns true if
// the actual update has been performed.
func (f *Filtering) updateIntl(flt *filter) (ok bool, err error) {
log.Tracef("downloading update for filter %d from %s", flt.ID, flt.URL)
var name string
var rnum, n int
var cs uint32
var tmpFile *os.File
tmpFile, err = os.CreateTemp(filepath.Join(Context.getDataDir(), filterDir), "")
if err != nil {
return false, err
}
defer func() {
err = errors.WithDeferred(err, finalizeUpdate(tmpFile, flt, ok, name, rnum, cs))
ok = ok && err == nil
if ok {
log.Printf("updated filter %d: %d bytes, %d rules", flt.ID, n, rnum)
}
}()
// Change the default 0o600 permission to something more acceptable by
// end users.
//
// See https://github.com/AdguardTeam/AdGuardHome/issues/3198.
if err = tmpFile.Chmod(0o644); err != nil {
return false, fmt.Errorf("changing file mode: %w", err)
}
var r io.Reader
if filepath.IsAbs(flt.URL) {
var file io.ReadCloser
file, err = os.Open(flt.URL)
if err != nil {
return false, fmt.Errorf("open file: %w", err)
}
defer func() { err = errors.WithDeferred(err, file.Close()) }()
r = file
} else {
var resp *http.Response
resp, err = Context.client.Get(flt.URL)
if err != nil {
log.Printf("requesting filter from %s, skip: %s", flt.URL, err)
return false, err
}
defer func() { err = errors.WithDeferred(err, resp.Body.Close()) }()
if resp.StatusCode != http.StatusOK {
log.Printf("got status code %d from %s, skip", resp.StatusCode, flt.URL)
return false, fmt.Errorf("got status code != 200: %d", resp.StatusCode)
}
r = resp.Body
}
name, rnum, cs, n, err = f.processUpdate(r, tmpFile, flt)
return cs != flt.checksum, err
}
// loads filter contents from the file in dataDir
func (f *Filtering) load(filter *filter) (err error) {
filterFilePath := filter.Path()
log.Tracef("filtering: loading filter %d contents to: %s", filter.ID, filterFilePath)
file, err := os.Open(filterFilePath)
if errors.Is(err, os.ErrNotExist) {
// Do nothing, file doesn't exist.
return nil
} else if err != nil {
return fmt.Errorf("opening filter file: %w", err)
}
defer func() { err = errors.WithDeferred(err, file.Close()) }()
st, err := file.Stat()
if err != nil {
return fmt.Errorf("getting filter file stat: %w", err)
}
log.Tracef("filtering: File %s, id %d, length %d", filterFilePath, filter.ID, st.Size())
rulesCount, checksum, _ := f.parseFilterContents(file)
filter.RulesCount = rulesCount
filter.checksum = checksum
filter.LastUpdated = st.ModTime()
return nil
}
// Clear filter rules
func (filter *filter) unload() {
filter.RulesCount = 0
filter.checksum = 0
}
// Path to the filter contents
func (filter *filter) Path() string {
return filepath.Join(Context.getDataDir(), filterDir, strconv.FormatInt(filter.ID, 10)+".txt")
}
func enableFilters(async bool) {
config.RLock()
defer config.RUnlock()
enableFiltersLocked(async)
}
func enableFiltersLocked(async bool) {
filters := []filtering.Filter{{
ID: filtering.CustomListID,
Data: []byte(strings.Join(config.UserRules, "\n")),
}}
for _, filter := range config.Filters {
if !filter.Enabled {
continue
}
filters = append(filters, filtering.Filter{
ID: filter.ID,
FilePath: filter.Path(),
})
}
var allowFilters []filtering.Filter
for _, filter := range config.WhitelistFilters {
if !filter.Enabled {
continue
}
allowFilters = append(allowFilters, filtering.Filter{
ID: filter.ID,
FilePath: filter.Path(),
})
}
if err := Context.dnsFilter.SetFilters(filters, allowFilters, async); err != nil {
log.Debug("enabling filters: %s", err)
}
Context.dnsFilter.SetEnabled(config.DNS.FilteringEnabled)
}