/
handler.go
282 lines (237 loc) · 6.19 KB
/
handler.go
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package sni
import (
"bufio"
"bytes"
"context"
"crypto/tls"
"encoding/base64"
"encoding/binary"
"errors"
"hash/crc32"
"io"
"net"
"net/http"
"net/http/httputil"
"time"
"github.com/go-gost/core/bypass"
"github.com/go-gost/core/chain"
"github.com/go-gost/core/handler"
"github.com/go-gost/core/logger"
md "github.com/go-gost/core/metadata"
dissector "github.com/go-gost/tls-dissector"
ctxvalue "github.com/go-gost/x/ctx"
xio "github.com/go-gost/x/internal/io"
netpkg "github.com/go-gost/x/internal/net"
"github.com/go-gost/x/registry"
)
func init() {
registry.HandlerRegistry().Register("sni", NewHandler)
}
type sniHandler struct {
router *chain.Router
md metadata
options handler.Options
}
func NewHandler(opts ...handler.Option) handler.Handler {
options := handler.Options{}
for _, opt := range opts {
opt(&options)
}
h := &sniHandler{
options: options,
}
return h
}
func (h *sniHandler) Init(md md.Metadata) (err error) {
if err = h.parseMetadata(md); err != nil {
return
}
h.router = h.options.Router
if h.router == nil {
h.router = chain.NewRouter(chain.LoggerRouterOption(h.options.Logger))
}
return nil
}
func (h *sniHandler) Handle(ctx context.Context, conn net.Conn, opts ...handler.HandleOption) error {
defer conn.Close()
start := time.Now()
log := h.options.Logger.WithFields(map[string]any{
"remote": conn.RemoteAddr().String(),
"local": conn.LocalAddr().String(),
})
log.Infof("%s <> %s", conn.RemoteAddr(), conn.LocalAddr())
defer func() {
log.WithFields(map[string]any{
"duration": time.Since(start),
}).Infof("%s >< %s", conn.RemoteAddr(), conn.LocalAddr())
}()
if !h.checkRateLimit(conn.RemoteAddr()) {
return nil
}
var hdr [dissector.RecordHeaderLen]byte
if _, err := io.ReadFull(conn, hdr[:]); err != nil {
log.Error(err)
return err
}
rw := xio.NewReadWriter(io.MultiReader(bytes.NewReader(hdr[:]), conn), conn)
tlsVersion := binary.BigEndian.Uint16(hdr[1:3])
if hdr[0] == dissector.Handshake &&
(tlsVersion >= tls.VersionTLS10 && tlsVersion <= tls.VersionTLS13) {
return h.handleHTTPS(ctx, rw, conn.RemoteAddr(), log)
}
return h.handleHTTP(ctx, rw, conn.RemoteAddr(), log)
}
func (h *sniHandler) handleHTTP(ctx context.Context, rw io.ReadWriter, raddr net.Addr, log logger.Logger) error {
req, err := http.ReadRequest(bufio.NewReader(rw))
if err != nil {
return err
}
if log.IsLevelEnabled(logger.TraceLevel) {
dump, _ := httputil.DumpRequest(req, false)
log.Trace(string(dump))
}
host := req.Host
if _, _, err := net.SplitHostPort(host); err != nil {
host = net.JoinHostPort(host, "80")
}
log = log.WithFields(map[string]any{
"host": host,
})
if h.options.Bypass != nil && h.options.Bypass.Contains(ctx, "tcp", host, bypass.WithPathOption(req.RequestURI)) {
log.Debugf("bypass: %s %s", host, req.RequestURI)
return nil
}
switch h.md.hash {
case "host":
ctx = ctxvalue.ContextWithHash(ctx, &ctxvalue.Hash{Source: host})
}
cc, err := h.router.Dial(ctx, "tcp", host)
if err != nil {
log.Error(err)
return err
}
defer cc.Close()
t := time.Now()
log.Infof("%s <-> %s", raddr, host)
defer func() {
log.WithFields(map[string]any{
"duration": time.Since(t),
}).Infof("%s >-< %s", raddr, host)
}()
if err := req.Write(cc); err != nil {
log.Error(err)
return err
}
var rw2 io.ReadWriter = cc
if log.IsLevelEnabled(logger.TraceLevel) {
var buf bytes.Buffer
resp, err := http.ReadResponse(bufio.NewReader(io.TeeReader(cc, &buf)), req)
if err != nil {
log.Error(err)
return err
}
defer resp.Body.Close()
dump, _ := httputil.DumpResponse(resp, false)
log.Trace(string(dump))
rw2 = xio.NewReadWriter(io.MultiReader(&buf, cc), cc)
}
netpkg.Transport(rw, rw2)
return nil
}
func (h *sniHandler) handleHTTPS(ctx context.Context, rw io.ReadWriter, raddr net.Addr, log logger.Logger) error {
buf := new(bytes.Buffer)
host, err := h.decodeHost(io.TeeReader(rw, buf))
if err != nil {
log.Error(err)
return err
}
if _, _, err := net.SplitHostPort(host); err != nil {
host = net.JoinHostPort(host, "443")
}
log = log.WithFields(map[string]any{
"dst": host,
})
log.Debugf("%s >> %s", raddr, host)
if h.options.Bypass != nil && h.options.Bypass.Contains(ctx, "tcp", host) {
log.Debug("bypass: ", host)
return nil
}
switch h.md.hash {
case "host":
ctx = ctxvalue.ContextWithHash(ctx, &ctxvalue.Hash{Source: host})
}
cc, err := h.router.Dial(ctx, "tcp", host)
if err != nil {
log.Error(err)
return err
}
defer cc.Close()
t := time.Now()
log.Infof("%s <-> %s", raddr, host)
netpkg.Transport(xio.NewReadWriter(io.MultiReader(buf, rw), rw), cc)
log.WithFields(map[string]any{
"duration": time.Since(t),
}).Infof("%s >-< %s", raddr, host)
return nil
}
func (h *sniHandler) decodeHost(r io.Reader) (host string, err error) {
record, err := dissector.ReadRecord(r)
if err != nil {
return
}
clientHello := dissector.ClientHelloMsg{}
if err = clientHello.Decode(record.Opaque); err != nil {
return
}
var extensions []dissector.Extension
for _, ext := range clientHello.Extensions {
if ext.Type() == 0xFFFE {
b, _ := ext.Encode()
if v, err := h.decodeServerName(string(b)); err == nil {
host = v
}
continue
}
extensions = append(extensions, ext)
}
clientHello.Extensions = extensions
for _, ext := range clientHello.Extensions {
if ext.Type() == dissector.ExtServerName {
snExtension := ext.(*dissector.ServerNameExtension)
if host == "" {
host = snExtension.Name
} else {
snExtension.Name = host
}
break
}
}
return
}
func (h *sniHandler) decodeServerName(s string) (string, error) {
b, err := base64.RawURLEncoding.DecodeString(s)
if err != nil {
return "", err
}
if len(b) < 4 {
return "", errors.New("invalid name")
}
v, err := base64.RawURLEncoding.DecodeString(string(b[4:]))
if err != nil {
return "", err
}
if crc32.ChecksumIEEE(v) != binary.BigEndian.Uint32(b[:4]) {
return "", errors.New("invalid name")
}
return string(v), nil
}
func (h *sniHandler) checkRateLimit(addr net.Addr) bool {
if h.options.RateLimiter == nil {
return true
}
host, _, _ := net.SplitHostPort(addr.String())
if limiter := h.options.RateLimiter.Limiter(host); limiter != nil {
return limiter.Allow(1)
}
return true
}