miracle091/dnscrypt-proxy
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dnscrypt-proxy
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Revert "Try to understand how cache files are updated" 

This reverts commit 92ed5b95e0.
This commit is contained in:
Frank Denis 2023-04-07 15:16:15 +02:00
parent 6d826afac5
commit 0f30b3b028
3 changed files with 51 additions and 57 deletions
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2
dnscrypt-proxy/config.go
View File

@ -894,7 +894,7 @@ func (config *Config) loadSource(proxy *Proxy, cfgSourceName string, cfgSource *
cfgSource.Prefix,
)
if err != nil {
if len(source.bin) <= 0 {
if len(source.in) <= 0 {
dlog.Criticalf("Unable to retrieve source [%s]: [%s]", cfgSourceName, err)
return err
}

98
dnscrypt-proxy/sources.go
View File

@ -3,10 +3,10 @@ package main
import (
"bytes"
"fmt"
"math"
"math/rand"
"net/url"
"os"
"path/filepath"
"strings"
"time"
@ -31,14 +31,13 @@ const (
type Source struct {
name string
urls []*url.URL
bin []byte // copy of the file content - there's something wrong in our logic, we shouldn't need to keep that in memory
sig []byte // copy of the signature
format SourceFormat
in []byte
minisignKey *minisign.PublicKey
cacheFile string
prefix string
cacheTTL, prefetchDelay time.Duration
refresh time.Time
format SourceFormat
prefix string
}
func (source *Source) checkSignature(bin, sig []byte) (err error) {
@ -49,10 +48,11 @@ func (source *Source) checkSignature(bin, sig []byte) (err error) {
return err
}
// timeNow() can be replaced by tests to provide a static value
// timeNow can be replaced by tests to provide a static value
var timeNow = time.Now
func (source *Source) fetchFromCache(now time.Time) (delay time.Duration, bin []byte, sig []byte, err error) {
func (source *Source) fetchFromCache(now time.Time) (delay time.Duration, err error) {
var bin, sig []byte
if bin, err = os.ReadFile(source.cacheFile); err != nil {
return
}
@ -62,13 +62,14 @@ func (source *Source) fetchFromCache(now time.Time) (delay time.Duration, bin []
if err = source.checkSignature(bin, sig); err != nil {
return
}
source.in = bin
var fi os.FileInfo
if fi, err = os.Stat(source.cacheFile); err != nil {
return
}
if elapsed := now.Sub(fi.ModTime()); elapsed < source.cacheTTL {
delay = source.prefetchDelay - elapsed
dlog.Debugf("Source [%s] cache file [%s] is still fresh, next update in %v min", source.name, source.cacheFile, math.Round(delay.Minutes()))
dlog.Debugf("Source [%s] cache file [%s] is still fresh, next update: %v", source.name, source.cacheFile, delay)
} else {
dlog.Debugf("Source [%s] cache file [%s] needs to be refreshed", source.name, source.cacheFile)
}
@ -97,25 +98,25 @@ func writeSource(f string, bin, sig []byte) (err error) {
return fSig.Commit()
}
// Update the cache file with the new data
func (source *Source) updateCache(bin, sig []byte, now time.Time) error {
func (source *Source) writeToCache(bin, sig []byte, now time.Time) {
f := source.cacheFile
// If the data and signature are unchanged, update the files timestamps only
if bin != nil && bytes.Equal(source.bin, bin) && sig != nil && bytes.Equal(source.sig, sig) {
dlog.Debugf("Source [%s] content and signature are unchanged", source.name)
if err := os.Chtimes(f, now, now); err != nil {
return err
var writeErr error // an error writing cache isn't fatal
defer func() {
source.in = bin
if writeErr == nil {
return
}
if err := os.Chtimes(f+".minisig", now, now); err != nil {
return err
if absPath, absErr := filepath.Abs(f); absErr == nil {
f = absPath
}
dlog.Warnf("%s: %s", f, writeErr)
}()
if !bytes.Equal(source.in, bin) {
if writeErr = writeSource(f, bin, sig); writeErr != nil {
return
}
return nil
}
if err := writeSource(f, bin, sig); err != nil {
dlog.Warnf("Source [%s] failed to update cache file [%s]: %v", source.name, f, err)
return err
}
return nil
writeErr = os.Chtimes(f, now, now)
}
func (source *Source) parseURLs(urls []string) {
@ -133,10 +134,11 @@ func fetchFromURL(xTransport *XTransport, u *url.URL) (bin []byte, err error) {
return bin, err
}
func (source *Source) fetchWithCache(xTransport *XTransport, now time.Time) (delay time.Duration, bin []byte, sig []byte, err error) {
if delay, bin, sig, err = source.fetchFromCache(now); err != nil {
func (source *Source) fetchWithCache(xTransport *XTransport, now time.Time) (delay time.Duration, err error) {
if delay, err = source.fetchFromCache(now); err != nil {
if len(source.urls) == 0 {
dlog.Fatalf("Source [%s] cache file [%s] not present and no valid URL", source.name, source.cacheFile)
dlog.Errorf("Source [%s] cache file [%s] not present and no valid URL", source.name, source.cacheFile)
return
}
dlog.Debugf("Source [%s] cache file [%s] not present", source.name, source.cacheFile)
}
@ -146,9 +148,10 @@ func (source *Source) fetchWithCache(xTransport *XTransport, now time.Time) (del
}()
}
if len(source.urls) == 0 || delay > 0 {
source.sig = sig
return delay, bin, sig, nil // source is still valid
return
}
delay = MinimumPrefetchInterval
var bin, sig []byte
for _, srcURL := range source.urls {
dlog.Infof("Source [%s] loading from URL [%s]", source.name, srcURL)
sigURL := &url.URL{}
@ -168,13 +171,11 @@ func (source *Source) fetchWithCache(xTransport *XTransport, now time.Time) (del
dlog.Debugf("Source [%s] failed signature check using URL [%s]", source.name, srcURL)
}
if err != nil {
return MinimumPrefetchInterval, nil, nil, err
return
}
if err := source.updateCache(bin, sig, now); err != nil {
return MinimumPrefetchInterval, bin, sig, err // keep using the old data
}
source.sig = sig
return source.prefetchDelay, bin, sig, nil
source.writeToCache(bin, sig, now)
delay = source.prefetchDelay
return
}
// NewSource loads a new source using the given cacheFile and urls, ensuring it has a valid signature
@ -210,14 +211,10 @@ func NewSource(
return source, err
}
source.parseURLs(urls)
_, bin, sig, err := source.fetchWithCache(xTransport, timeNow())
if err != nil {
return nil, err
if _, err = source.fetchWithCache(xTransport, timeNow()); err == nil {
dlog.Noticef("Source [%s] loaded", name)
}
dlog.Noticef("Source [%s] loaded", name)
source.bin = bin
source.sig = sig
return source, err
return
}
// PrefetchSources downloads latest versions of given sources, ensuring they have a valid signature before caching
@ -229,16 +226,13 @@ func PrefetchSources(xTransport *XTransport, sources []*Source) time.Duration {
continue
}
dlog.Debugf("Prefetching [%s]", source.name)
delay, bin, sig, err := source.fetchWithCache(xTransport, now)
if err != nil {
if delay, err := source.fetchWithCache(xTransport, now); err != nil {
dlog.Infof("Prefetching [%s] failed: %v, will retry in %v", source.name, err, interval)
continue
}
source.bin = bin
source.sig = sig
dlog.Debugf("Prefetching [%s] succeeded, next update in %v min", source.name, math.Round(delay.Minutes()))
if delay >= MinimumPrefetchInterval && (interval == MinimumPrefetchInterval || interval > delay) {
interval = delay
} else {
dlog.Debugf("Prefetching [%s] succeeded, next update: %v", source.name, delay)
if delay >= MinimumPrefetchInterval && (interval == MinimumPrefetchInterval || interval > delay) {
interval = delay
}
}
}
return interval
@ -260,8 +254,8 @@ func (source *Source) parseV2() ([]RegisteredServer, error) {
stampErrs = append(stampErrs, stampErr)
dlog.Warn(stampErr)
}
bin := string(source.bin)
parts := strings.Split(bin, "## ")
in := string(source.in)
parts := strings.Split(in, "## ")
if len(parts) < 2 {
return registeredServers, fmt.Errorf("Invalid format for source at [%v]", source.urls)
}

8
dnscrypt-proxy/sources_test.go
View File

@ -284,9 +284,9 @@ func prepSourceTestCache(t *testing.T, d *SourceTestData, e *SourceTestExpect, s
e.cache = []SourceFixture{d.fixtures[state][source], d.fixtures[state][source+".minisig"]}
switch state {
case TestStateCorrect:
e.Source.bin, e.success = e.cache[0].content, true
e.Source.in, e.success = e.cache[0].content, true
case TestStateExpired:
e.Source.bin = e.cache[0].content
e.Source.in = e.cache[0].content
case TestStatePartial, TestStatePartialSig:
e.err = "signature"
case TestStateMissing, TestStateMissingSig, TestStateOpenErr, TestStateOpenSigErr:
@ -339,7 +339,7 @@ func prepSourceTestDownload(
switch state {
case TestStateCorrect:
e.cache = []SourceFixture{d.fixtures[state][source], d.fixtures[state][source+".minisig"]}
e.Source.bin, e.success = e.cache[0].content, true
e.Source.in, e.success = e.cache[0].content, true
fallthrough
case TestStateMissingSig, TestStatePartial, TestStatePartialSig, TestStateReadSigErr:
d.reqExpect[path+".minisig"]++
@ -477,7 +477,7 @@ func TestPrefetchSources(t *testing.T) {
e.mtime = d.timeUpd
s := &Source{}
*s = *e.Source
s.bin = nil
s.in = nil
sources = append(sources, s)
expects = append(expects, e)
}