Merge pull request #33 from Snawoot/localaddr_hint

Localaddr hint

README.md

@@ -194,6 +194,8 @@ Usage of /home/user/go/bin/dumbproxy:
     	colon-separated list of enabled ciphers
   -disable-http2
     	disable HTTP2
+  -ip-hints value
+    	a comma-separated list of source addresses to use on dial attempts. Example: "10.0.0.1,fe80::2,0.0.0.0,::"
   -key string
     	key for TLS certificate
   -list-ciphers
@@ -206,6 +208,8 @@ Usage of /home/user/go/bin/dumbproxy:
     	upstream proxy URL. Can be repeated multiple times to chain proxies. Examples: socks5h://127.0.0.1:9050; https://user:password@example.com:443
   -timeout duration
     	timeout for network operations (default 10s)
+  -user-ip-hints
+    	allow IP hints to be specified by user in X-Src-IP-Hints header
   -verbosity int
     	logging verbosity (10 - debug, 20 - info, 30 - warning, 40 - error, 50 - critical) (default 20)
   -version

go.mod

@@ -5,6 +5,7 @@ go 1.13
 require (
 	github.com/GehirnInc/crypt v0.0.0-20230320061759-8cc1b52080c5 // indirect
 	github.com/coreos/go-systemd/v22 v22.5.0 // indirect
+	github.com/hashicorp/go-multierror v1.1.1 // indirect
 	github.com/kr/pretty v0.3.1 // indirect
 	github.com/tg123/go-htpasswd v1.2.1
 	golang.org/x/crypto v0.7.0

go.sum

@@ -8,6 +8,10 @@ github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSs
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/godbus/dbus/v5 v5.0.4/go.mod h1:xhWf0FNVPg57R7Z0UbKHbJfkEywrmjJnf7w5xrFpKfA=
+github.com/hashicorp/errwrap v1.0.0 h1:hLrqtEDnRye3+sgx6z4qVLNuviH3MR5aQ0ykNJa/UYA=
+github.com/hashicorp/errwrap v1.0.0/go.mod h1:YH+1FKiLXxHSkmPseP+kNlulaMuP3n2brvKWEqk/Jc4=
+github.com/hashicorp/go-multierror v1.1.1 h1:H5DkEtf6CXdFp0N0Em5UCwQpXMWke8IA0+lD48awMYo=
+github.com/hashicorp/go-multierror v1.1.1/go.mod h1:iw975J/qwKPdAO1clOe2L8331t/9/fmwbPZ6JB6eMoM=
 github.com/kr/pretty v0.2.1/go.mod h1:ipq/a2n7PKx3OHsz4KJII5eveXtPO4qwEXGdVfWzfnI=
 github.com/kr/pretty v0.3.1 h1:flRD4NNwYAUpkphVc1HcthR4KEIFJ65n8Mw5qdRn3LE=
 github.com/kr/pretty v0.3.1/go.mod h1:hoEshYVHaxMs3cyo3Yncou5ZscifuDolrwPKZanG3xk=

handler.go

@@ -10,6 +10,8 @@ import (
 	"time"
 )
 
+const HintsHeaderName = "X-Src-IP-Hints"
+
 type HandlerDialer interface {
 	DialContext(ctx context.Context, net, address string) (net.Conn, error)
 }
@@ -22,11 +24,14 @@ type ProxyHandler struct {
 	httptransport http.RoundTripper
 	outbound      map[string]string
 	outboundMux   sync.RWMutex
+	userIPHints   bool
 }
 
-func NewProxyHandler(timeout time.Duration, auth Auth, dialer HandlerDialer, logger *CondLogger) *ProxyHandler {
+func NewProxyHandler(timeout time.Duration, auth Auth, dialer HandlerDialer,
+	userIPHints bool, logger *CondLogger) *ProxyHandler {
 	httptransport := &http.Transport{
 		DialContext:       dialer.DialContext,
+		DisableKeepAlives: userIPHints,
 	}
 	return &ProxyHandler{
 		timeout:       timeout,
@@ -35,6 +40,7 @@ func NewProxyHandler(timeout time.Duration, auth Auth, dialer HandlerDialer, log
 		dialer:        dialer,
 		httptransport: httptransport,
 		outbound:      make(map[string]string),
+		userIPHints:   userIPHints,
 	}
 }
 
@@ -133,6 +139,20 @@ func (s *ProxyHandler) ServeHTTP(wr http.ResponseWriter, req *http.Request) {
 	if !ok {
 		return
 	}
+	if s.userIPHints {
+		hintValues := req.Header.Values(HintsHeaderName)
+		if len(hintValues) > 0 {
+			req.Header.Del(HintsHeaderName)
+			if hintIPs, err := parseIPList(hintValues[0]); err != nil {
+				s.logger.Info("Request: %v %q %v %v %v -- bad IP hint header: %q", req.RemoteAddr, username, req.Proto, req.Method, req.URL, hintValues[0])
+				http.Error(wr, BAD_REQ_MSG, http.StatusBadRequest)
+				return
+			} else {
+				newCtx := context.WithValue(req.Context(), BoundDialerContextKey{}, hintIPs)
+				req = req.WithContext(newCtx)
+			}
+		}
+	}
 	delHopHeaders(req.Header)
 	if isConnect {
 		s.HandleTunnel(wr, req)

hintdialer.go

@@ -0,0 +1,138 @@
+package main
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"net"
+
+	"github.com/hashicorp/go-multierror"
+)
+
+var (
+	ErrNoSuitableAddress  = errors.New("no suitable address")
+	ErrBadIPAddressLength = errors.New("bad IP address length")
+	ErrUnknownNetwork     = errors.New("unknown network")
+)
+
+type BoundDialerContextKey struct{}
+
+type BoundDialerDefaultSink interface {
+	DialContext(ctx context.Context, network, address string) (net.Conn, error)
+}
+
+type BoundDialer struct {
+	defaultDialer BoundDialerDefaultSink
+	defaultHints  []net.IP
+}
+
+func NewBoundDialer(defaultDialer BoundDialerDefaultSink, defaultHints []net.IP) *BoundDialer {
+	if defaultDialer == nil {
+		defaultDialer = &net.Dialer{}
+	}
+	return &BoundDialer{
+		defaultDialer: defaultDialer,
+		defaultHints:  defaultHints,
+	}
+}
+
+func (d *BoundDialer) DialContext(ctx context.Context, network, address string) (net.Conn, error) {
+	hints := d.defaultHints
+	if hintsOverride := ctx.Value(BoundDialerContextKey{}); hintsOverride != nil {
+		if hintsOverrideValue, ok := hintsOverride.([]net.IP); ok {
+			hints = hintsOverrideValue
+		}
+	}
+
+	if len(hints) == 0 {
+		return d.defaultDialer.DialContext(ctx, network, address)
+	}
+
+	var netBase string
+	switch network {
+	case "tcp", "tcp4", "tcp6":
+		netBase = "tcp"
+	case "udp", "udp4", "udp6":
+		netBase = "udp"
+	case "ip", "ip4", "ip6":
+		netBase = "ip"
+	default:
+		return d.defaultDialer.DialContext(ctx, network, address)
+	}
+
+	var resErr error
+	for _, lIP := range hints {
+		lAddr, restrictedNetwork, err := ipToLAddr(netBase, lIP)
+		if err != nil {
+			resErr = multierror.Append(resErr, fmt.Errorf("ipToLAddr(%q) failed: %w", lIP.String(), err))
+			continue
+		}
+		if network != netBase && network != restrictedNetwork {
+			continue
+		}
+
+		conn, err := (&net.Dialer{
+			LocalAddr: lAddr,
+		}).DialContext(ctx, restrictedNetwork, address)
+		if err != nil {
+			resErr = multierror.Append(resErr, fmt.Errorf("dial failed: %w", err))
+		} else {
+			return conn, nil
+		}
+	}
+
+	if resErr == nil {
+		resErr = ErrNoSuitableAddress
+	}
+	return nil, resErr
+}
+
+func (d *BoundDialer) Dial(network, address string) (net.Conn, error) {
+	return d.DialContext(context.Background(), network, address)
+}
+
+func ipToLAddr(network string, ip net.IP) (net.Addr, string, error) {
+	v6 := true
+	if ip4 := ip.To4(); len(ip4) == net.IPv4len {
+		ip = ip4
+		v6 = false
+	} else if len(ip) != net.IPv6len {
+		return nil, "", ErrBadIPAddressLength
+	}
+
+	var lAddr net.Addr
+	var lNetwork string
+	switch network {
+	case "tcp", "tcp4", "tcp6":
+		lAddr = &net.TCPAddr{
+			IP: ip,
+		}
+		if v6 {
+			lNetwork = "tcp6"
+		} else {
+			lNetwork = "tcp4"
+		}
+	case "udp", "udp4", "udp6":
+		lAddr = &net.UDPAddr{
+			IP: ip,
+		}
+		if v6 {
+			lNetwork = "udp6"
+		} else {
+			lNetwork = "udp4"
+		}
+	case "ip", "ip4", "ip6":
+		lAddr = &net.IPAddr{
+			IP: ip,
+		}
+		if v6 {
+			lNetwork = "ip6"
+		} else {
+			lNetwork = "ip4"
+		}
+	default:
+		return nil, "", ErrUnknownNetwork
+	}
+
+	return lAddr, lNetwork, nil
+}

main.go

@@ -72,6 +72,8 @@ type CLIArgs struct {
 	passwdCost        int
 	positionalArgs    []string
 	proxy             []string
+	sourceIPHints     []net.IP
+	userIPHints       bool
 }
 
 func parse_args() CLIArgs {
@@ -101,6 +103,15 @@ func parse_args() CLIArgs {
 		args.proxy = append(args.proxy, p)
 		return nil
 	})
+	flag.Func("ip-hints", "a comma-separated list of source addresses to use on dial attempts. Example: \"10.0.0.1,fe80::2,0.0.0.0,::\"", func(p string) error {
+		list, err := parseIPList(p)
+		if err != nil {
+			return err
+		}
+		args.sourceIPHints = list
+		return nil
+	})
+	flag.BoolVar(&args.userIPHints, "user-ip-hints", false, "allow IP hints to be specified by user in X-Src-IP-Hints header")
 	flag.Parse()
 	args.positionalArgs = flag.Args()
 	return args
@@ -146,7 +157,7 @@ func run() int {
 	}
 	defer auth.Stop()
 
-	var dialer Dialer = new(net.Dialer)
+	var dialer Dialer = NewBoundDialer(new(net.Dialer), args.sourceIPHints)
 	for _, proxyURL := range args.proxy {
 		newDialer, err := proxyDialerFromURL(proxyURL, dialer)
 		if err != nil {
@@ -158,7 +169,7 @@ func run() int {
 
 	server := http.Server{
 		Addr:              args.bind_address,
-		Handler:           NewProxyHandler(args.timeout, auth, maybeWrapWithContextDialer(dialer), proxyLogger),
+		Handler:           NewProxyHandler(args.timeout, auth, maybeWrapWithContextDialer(dialer), args.userIPHints, proxyLogger),
 		ErrorLog:          log.New(logWriter, "HTTPSRV : ", log.LstdFlags|log.Lshortfile),
 		ReadTimeout:       0,
 		ReadHeaderTimeout: 0,

utils.go

@@ -369,3 +369,19 @@ func maybeWrapWithContextDialer(d Dialer) ContextDialer {
 	}
 	return wrappedDialer{d}
 }
+
+func parseIPList(list string) ([]net.IP, error) {
+	res := make([]net.IP, 0)
+	for _, elem := range strings.Split(list, ",") {
+		elem = strings.TrimSpace(elem)
+		if len(elem) == 0 {
+			continue
+		}
+		if parsed := net.ParseIP(elem); parsed == nil {
+			return nil, fmt.Errorf("unable to parse IP address %q", elem)
+		} else {
+			res = append(res, parsed)
+		}
+	}
+	return res, nil
+}