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utils.go
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utils.go
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// Copyright (C) 2020-2021, IrineSistiana
//
// This file is part of mosdns.
//
// mosdns is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// mosdns is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <https://www.gnu.org/licenses/>.
package utils
import (
"context"
"crypto/ecdsa"
"crypto/elliptic"
"crypto/rand"
"crypto/tls"
"crypto/x509"
"crypto/x509/pkix"
"encoding/pem"
"errors"
"fmt"
"github.com/IrineSistiana/mosdns/dispatcher/handler"
"github.com/miekg/dns"
"go.uber.org/zap"
"golang.org/x/sync/singleflight"
"io/ioutil"
"math/big"
"net"
"regexp"
"strings"
"sync"
"time"
"unsafe"
)
// GetIPFromAddr returns net.IP from net.Addr.
// Will return nil if no ip address can be parsed.
func GetIPFromAddr(addr net.Addr) (ip net.IP) {
switch v := addr.(type) {
case *net.TCPAddr:
return v.IP
case *net.UDPAddr:
return v.IP
case *net.IPNet:
return v.IP
case *NetAddr:
return v.IP()
default:
return parseIPFromAddr(addr.String())
}
}
// SplitSchemeAndHost splits addr to protocol and host.
func SplitSchemeAndHost(addr string) (protocol, host string) {
if protocol, host, ok := SplitString2(addr, "://"); ok {
return protocol, host
} else {
return "", addr
}
}
// NetAddr implements net.Addr interface.
type NetAddr struct {
addr string
network string
parseIPOnce sync.Once
ip net.IP // will be non-nil if addr is an ip addr.
}
func NewNetAddr(addr string, network string) *NetAddr {
return &NetAddr{addr: addr, network: network}
}
func (n *NetAddr) Network() string {
return n.network
}
func (n *NetAddr) String() string {
return n.addr
}
func (n *NetAddr) IP() net.IP {
n.parseIPOnce.Do(func() {
n.ip = parseIPFromAddr(n.addr)
})
return n.ip
}
func parseIPFromAddr(s string) net.IP {
ipStr, _, err := net.SplitHostPort(s)
if err != nil {
return nil
}
return net.ParseIP(ipStr)
}
// GetMsgKey unpacks m and set its id to salt.
func GetMsgKey(m *dns.Msg, salt uint16) (string, error) {
wireMsg, err := m.Pack()
if err != nil {
return "", err
}
wireMsg[0] = byte(salt >> 8)
wireMsg[1] = byte(salt)
return BytesToStringUnsafe(wireMsg), nil
}
// BytesToStringUnsafe converts bytes to string.
func BytesToStringUnsafe(b []byte) string {
return *(*string)(unsafe.Pointer(&b))
}
// LoadCertPool reads and loads certificates in certs.
func LoadCertPool(certs []string) (*x509.CertPool, error) {
rootCAs := x509.NewCertPool()
for _, cert := range certs {
b, err := ioutil.ReadFile(cert)
if err != nil {
return nil, err
}
if ok := rootCAs.AppendCertsFromPEM(b); !ok {
return nil, fmt.Errorf("no certificate was successfully parsed in %s", cert)
}
}
return rootCAs, nil
}
// GenerateCertificate generates a ecdsa certificate with given dnsName.
// This should only use in test.
func GenerateCertificate(dnsName string) (cert tls.Certificate, err error) {
key, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
if err != nil {
return
}
//serial number
serialNumberLimit := new(big.Int).Lsh(big.NewInt(1), 128)
serialNumber, err := rand.Int(rand.Reader, serialNumberLimit)
if err != nil {
err = fmt.Errorf("generate serial number: %w", err)
return
}
template := x509.Certificate{
SerialNumber: serialNumber,
Subject: pkix.Name{CommonName: dnsName},
DNSNames: []string{dnsName},
NotBefore: time.Now(),
NotAfter: time.Now().AddDate(10, 0, 0),
KeyUsage: x509.KeyUsageKeyEncipherment | x509.KeyUsageDigitalSignature,
ExtKeyUsage: []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth},
BasicConstraintsValid: true,
}
certDER, err := x509.CreateCertificate(rand.Reader, &template, &template, &key.PublicKey, key)
if err != nil {
return
}
b, err := x509.MarshalPKCS8PrivateKey(key)
if err != nil {
return
}
keyPEM := pem.EncodeToMemory(&pem.Block{Type: "EC PRIVATE KEY", Bytes: b})
certPEM := pem.EncodeToMemory(&pem.Block{Type: "CERTIFICATE", Bytes: certDER})
return tls.X509KeyPair(certPEM, keyPEM)
}
var charBlockExpr = regexp.MustCompile("\\S+")
// SplitLineReg extracts words from s by using regexp "\S+".
func SplitLineReg(s string) []string {
return charBlockExpr.FindAllString(s, -1)
}
// SplitLine removes all spaces " " and extracts words from s.
func SplitLine(s string) []string {
t := strings.Split(s, " ")
t2 := t[:0]
for _, sub := range t {
if sub != "" {
t2 = append(t2, sub)
}
}
return t2
}
// RemoveComment removes comment after "symbol".
func RemoveComment(s, symbol string) string {
if i := strings.Index(s, symbol); i >= 0 {
return s[:i]
}
return s
}
//SplitString2 split s to two parts by given symbol
func SplitString2(s, symbol string) (s1 string, s2 string, ok bool) {
if len(symbol) == 0 {
return "", s, true
}
if i := strings.Index(s, symbol); i >= 0 {
return s[:i], s[i+len(symbol):], true
}
return "", "", false
}
type ExchangeSingleFlightGroup struct {
singleflight.Group
}
func (g *ExchangeSingleFlightGroup) Exchange(ctx context.Context, qCtx *handler.Context, upstreams []Upstream, logger *zap.Logger) (r *dns.Msg, err error) {
key, err := GetMsgKey(qCtx.Q(), 0)
if err != nil {
return nil, fmt.Errorf("failed to caculate msg key, %w", err)
}
v, err, shared := g.Do(key, func() (interface{}, error) {
defer g.Forget(key)
return ExchangeParallel(ctx, qCtx, upstreams, logger)
})
if err != nil {
return nil, err
}
rUnsafe := v.(*dns.Msg)
if shared && rUnsafe != nil { // shared reply may has a different id and is not safe to modify.
r = rUnsafe.Copy()
r.Id = qCtx.Q().Id
return r, nil
}
return rUnsafe, nil
}
func BoolLogic(ctx context.Context, qCtx *handler.Context, fs []handler.Matcher, logicalAND bool) (matched bool, err error) {
if len(fs) == 0 {
return false, nil
}
for _, m := range fs {
matched, err = m.Match(ctx, qCtx)
if err != nil {
return false, err
}
if matched && !logicalAND {
return true, nil
}
if !matched && logicalAND {
return false, nil
}
}
return matched, nil
}
type Upstream interface {
// Exchange should not keep nor modify qCtx.
Exchange(qCtx *handler.Context) (*dns.Msg, error)
Address() string
Trusted() bool
}
type parallelResult struct {
r *dns.Msg
err error
from Upstream
}
func ExchangeParallel(ctx context.Context, qCtx *handler.Context, upstreams []Upstream, logger *zap.Logger) (r *dns.Msg, err error) {
t := len(upstreams)
if t == 0 {
return nil, errors.New("no upstream")
}
if t == 1 {
u := upstreams[0]
r, err = u.Exchange(qCtx)
if err != nil {
return nil, err
}
logger.Debug("response received", qCtx.InfoField(), zap.String("from", u.Address()))
return r, nil
}
c := make(chan *parallelResult, t) // use buf chan to avoid blocking.
qCopy := qCtx.CopyNoR() // qCtx is not safe for concurrent use.
for _, u := range upstreams {
u := u
go func() {
r, err := u.Exchange(qCopy)
c <- ¶llelResult{
r: r,
err: err,
from: u,
}
}()
}
for i := 0; i < t; i++ {
select {
case res := <-c:
if res.err != nil {
logger.Warn("upstream failed", qCtx.InfoField(), zap.String("from", res.from.Address()), zap.Error(res.err))
continue
}
if !res.from.Trusted() && res.r.Rcode != dns.RcodeSuccess {
logger.Debug("untrusted upstream returned an err rcode", qCtx.InfoField(), zap.String("from", res.from.Address()), zap.Int("rcode", res.r.Rcode))
continue
}
logger.Debug("response received", qCtx.InfoField(), zap.String("from", res.from.Address()))
return res.r, nil
case <-ctx.Done():
return nil, ctx.Err()
}
}
// all upstreams are failed
return nil, errors.New("no response")
}
// IsIPAddr returns true is s is a IP address. s can contain ":port".
func IsIPAddr(s string) bool {
host, _, err := net.SplitHostPort(s)
if err != nil {
return net.ParseIP(s) != nil
}
return net.ParseIP(host) != nil
}