forked from DNSCrypt/dnscrypt-proxy
/
plugin_cloak.go
181 lines (171 loc) · 4.56 KB
/
plugin_cloak.go
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package main
import (
"math/rand"
"net"
"strings"
"sync"
"time"
"unicode"
"github.com/jedisct1/dlog"
"github.com/miekg/dns"
)
type CloakedName struct {
target string
ipv4 []net.IP
ipv6 []net.IP
lastUpdate *time.Time
lineNo int
isIP bool
}
type PluginCloak struct {
sync.RWMutex
patternMatcher *PatternMatcher
ttl uint32
}
func (plugin *PluginCloak) Name() string {
return "cloak"
}
func (plugin *PluginCloak) Description() string {
return "Return a synthetic IP address or a flattened CNAME for specific names"
}
func (plugin *PluginCloak) Init(proxy *Proxy) error {
dlog.Noticef("Loading the set of cloaking rules from [%s]", proxy.cloakFile)
bin, err := ReadTextFile(proxy.cloakFile)
if err != nil {
return err
}
plugin.ttl = proxy.cloakTTL
plugin.patternMatcher = NewPatternMatcher()
cloakedNames := make(map[string]*CloakedName)
for lineNo, line := range strings.Split(string(bin), "\n") {
line = TrimAndStripInlineComments(line)
if len(line) == 0 {
continue
}
var target string
parts := strings.FieldsFunc(line, unicode.IsSpace)
if len(parts) == 2 {
line = strings.TrimFunc(parts[0], unicode.IsSpace)
target = strings.TrimFunc(parts[1], unicode.IsSpace)
} else if len(parts) > 2 {
dlog.Errorf("Syntax error in cloaking rules at line %d -- Unexpected space character", 1+lineNo)
continue
}
if len(line) == 0 || len(target) == 0 {
dlog.Errorf("Syntax error in cloaking rules at line %d -- Missing name or target", 1+lineNo)
continue
}
line = strings.ToLower(line)
cloakedName, found := cloakedNames[line]
if !found {
cloakedName = &CloakedName{}
}
if ip := net.ParseIP(target); ip != nil {
if ipv4 := ip.To4(); ipv4 != nil {
cloakedName.ipv4 = append((*cloakedName).ipv4, ipv4)
} else if ipv6 := ip.To16(); ipv6 != nil {
cloakedName.ipv6 = append((*cloakedName).ipv6, ipv6)
} else {
dlog.Errorf("Invalid IP address in cloaking rule at line %d", 1+lineNo)
continue
}
cloakedName.isIP = true
} else {
cloakedName.target = target
}
cloakedName.lineNo = lineNo + 1
cloakedNames[line] = cloakedName
}
for line, cloakedName := range cloakedNames {
if err := plugin.patternMatcher.Add(line, cloakedName, cloakedName.lineNo); err != nil {
return err
}
}
return nil
}
func (plugin *PluginCloak) Drop() error {
return nil
}
func (plugin *PluginCloak) Reload() error {
return nil
}
func (plugin *PluginCloak) Eval(pluginsState *PluginsState, msg *dns.Msg) error {
question := msg.Question[0]
if question.Qclass != dns.ClassINET || (question.Qtype != dns.TypeA && question.Qtype != dns.TypeAAAA) {
return nil
}
now := time.Now()
plugin.RLock()
_, _, xcloakedName := plugin.patternMatcher.Eval(pluginsState.qName)
if xcloakedName == nil {
plugin.RUnlock()
return nil
}
cloakedName := xcloakedName.(*CloakedName)
ttl, expired := plugin.ttl, false
if cloakedName.lastUpdate != nil {
if elapsed := uint32(now.Sub(*cloakedName.lastUpdate).Seconds()); elapsed < ttl {
ttl -= elapsed
} else {
expired = true
}
}
if !cloakedName.isIP && ((cloakedName.ipv4 == nil && cloakedName.ipv6 == nil) || expired) {
target := cloakedName.target
plugin.RUnlock()
foundIPs, err := net.LookupIP(target)
if err != nil {
return nil
}
plugin.Lock()
cloakedName.lastUpdate = &now
cloakedName.ipv4 = nil
cloakedName.ipv6 = nil
for _, foundIP := range foundIPs {
if ipv4 := foundIP.To4(); ipv4 != nil {
cloakedName.ipv4 = append(cloakedName.ipv4, foundIP)
if len(cloakedName.ipv4) >= 16 {
break
}
} else {
cloakedName.ipv6 = append(cloakedName.ipv6, foundIP)
if len(cloakedName.ipv6) >= 16 {
break
}
}
}
plugin.Unlock()
plugin.RLock()
}
var ip *net.IP
if question.Qtype == dns.TypeA {
ipLen := len(cloakedName.ipv4)
if ipLen > 0 {
ip = &cloakedName.ipv4[rand.Intn(ipLen)]
}
} else {
ipLen := len(cloakedName.ipv6)
if ipLen > 0 {
ip = &cloakedName.ipv6[rand.Intn(ipLen)]
}
}
plugin.RUnlock()
synth := EmptyResponseFromMessage(msg)
if ip == nil {
synth.Answer = []dns.RR{}
} else if question.Qtype == dns.TypeA {
rr := new(dns.A)
rr.Hdr = dns.RR_Header{Name: question.Name, Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: ttl}
rr.A = *ip
synth.Answer = []dns.RR{rr}
} else {
rr := new(dns.AAAA)
rr.Hdr = dns.RR_Header{Name: question.Name, Rrtype: dns.TypeAAAA, Class: dns.ClassINET, Ttl: ttl}
rr.AAAA = *ip
synth.Answer = []dns.RR{rr}
}
pluginsState.synthResponse = synth
pluginsState.action = PluginsActionSynth
pluginsState.returnCode = PluginsReturnCodeCloak
return nil
}