fix(egress): address P1 MITM bypass and P2 validation gaps

- Add SO_MARK transport to HTTP source fetches so outbound connections
  bypass the transparent iptables redirect (prevents MITM → active
  snapshot → singleflight deadlock on first fetch / TTL expiry)
- Add mark-based RETURN rule to transparent HTTP iptables chain
- Validate URL host presence, HTTP method, and header names/values
  at write time instead of failing silently at activation
- Remove default keyword from OpenAPI spec method field so generated
  TS client treats it as optional
- Regenerate JS and Python API clients

Author: Pangjiping

components/egress/pkg/credentialvault/source_http.go

@@ -21,6 +21,7 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"net"
 	"net/http"
 	"net/url"
 	"sync"
@@ -31,6 +32,10 @@ import (
 
 const httpSourceDefaultTimeout = 10 * time.Second
 
+func defaultTransportDialer() *net.Dialer {
+	return &net.Dialer{Timeout: 5 * time.Second}
+}
+
 type httpSource struct {
 	mu sync.RWMutex
 	sf singleflight.Group
@@ -172,15 +177,32 @@ func httpSourceFactory(raw json.RawMessage) (CredentialSource, error) {
 	if parsed.Scheme != "https" && parsed.Scheme != "http" {
 		return nil, fmt.Errorf("http credential source url must use http or https scheme, got %q", parsed.Scheme)
 	}
+	if parsed.Host == "" {
+		return nil, fmt.Errorf("http credential source url must include a host")
+	}
 	if cfg.Method == "" {
 		cfg.Method = http.MethodGet
 	}
+	if _, err := http.NewRequest(cfg.Method, cfg.URL, nil); err != nil {
+		return nil, fmt.Errorf("http credential source: invalid method or url: %w", err)
+	}
+	for name, value := range cfg.Headers {
+		if !headerFieldNamePattern.MatchString(name) {
+			return nil, fmt.Errorf("http credential source: invalid header name %q", name)
+		}
+		for i := range value {
+			if value[i] == '\r' || value[i] == '\n' {
+				return nil, fmt.Errorf("http credential source: header %q value contains CR/LF", name)
+			}
+		}
+	}
 	return &httpSource{
 		initialURL:     cfg.URL,
 		initialMethod:  cfg.Method,
 		initialHeaders: cfg.Headers,
 		client: &http.Client{
-			Timeout: httpSourceDefaultTimeout,
+			Timeout:   httpSourceDefaultTimeout,
+			Transport: httpSourceTransport(),
 			CheckRedirect: func(req *http.Request, via []*http.Request) error {
 				return errors.New("http credential source: redirects are not allowed")
 			},

components/egress/pkg/credentialvault/source_http_test.go

@@ -275,6 +275,43 @@ func TestHttpSourceFactoryRejectsRelativeURL(t *testing.T) {
 	require.ErrorContains(t, err, "must use http or https scheme")
 }
 
+func TestHttpSourceFactoryRejectsHostlessURL(t *testing.T) {
+	for _, u := range []string{"http:/token", "https:///token", "http://"} {
+		_, err := httpSourceFactory(mustMarshal(map[string]string{
+			"type": "http",
+			"url":  u,
+		}))
+		require.ErrorContains(t, err, "must include a host", u)
+	}
+}
+
+func TestHttpSourceFactoryRejectsInvalidMethod(t *testing.T) {
+	_, err := httpSourceFactory(mustMarshal(map[string]any{
+		"type":   "http",
+		"url":    "https://vault.example.com/cred",
+		"method": "BAD METHOD",
+	}))
+	require.ErrorContains(t, err, "invalid method")
+}
+
+func TestHttpSourceFactoryRejectsInvalidHeaderName(t *testing.T) {
+	_, err := httpSourceFactory(mustMarshal(map[string]any{
+		"type":    "http",
+		"url":     "https://vault.example.com/cred",
+		"headers": map[string]string{"Bad Header": "value"},
+	}))
+	require.ErrorContains(t, err, "invalid header name")
+}
+
+func TestHttpSourceFactoryRejectsHeaderValueWithCRLF(t *testing.T) {
+	_, err := httpSourceFactory(mustMarshal(map[string]any{
+		"type":    "http",
+		"url":     "https://vault.example.com/cred",
+		"headers": map[string]string{"X-Auth": "value\r\ninjection"},
+	}))
+	require.ErrorContains(t, err, "CR/LF")
+}
+
 func TestHttpSourceRejectsRedirects(t *testing.T) {
 	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		http.Redirect(w, r, "https://evil.example.com", http.StatusFound)

components/egress/pkg/credentialvault/source_http_transport_linux.go

@@ -0,0 +1,40 @@
+// Copyright 2026 Alibaba Group Holding Ltd.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//go:build linux
+
+package credentialvault
+
+import (
+	"net/http"
+	"syscall"
+
+	"golang.org/x/sys/unix"
+
+	"github.com/alibaba/opensandbox/egress/pkg/constants"
+)
+
+func httpSourceTransport() http.RoundTripper {
+	dialer := defaultTransportDialer()
+	dialer.Control = func(network, address string, c syscall.RawConn) error {
+		var opErr error
+		if err := c.Control(func(fd uintptr) {
+			opErr = unix.SetsockoptInt(int(fd), unix.SOL_SOCKET, unix.SO_MARK, constants.MarkValue)
+		}); err != nil {
+			return err
+		}
+		return opErr
+	}
+	return &http.Transport{DialContext: dialer.DialContext}
+}

components/egress/pkg/credentialvault/source_http_transport_other.go

@@ -0,0 +1,23 @@
+// Copyright 2026 Alibaba Group Holding Ltd.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//go:build !linux
+
+package credentialvault
+
+import "net/http"
+
+func httpSourceTransport() http.RoundTripper {
+	return &http.Transport{DialContext: defaultTransportDialer().DialContext}
+}

components/egress/pkg/iptables/transparent.go

@@ -21,6 +21,7 @@ import (
 	"strconv"
 	"strings"
 
+	"github.com/alibaba/opensandbox/egress/pkg/constants"
 	"github.com/alibaba/opensandbox/egress/pkg/log"
 )
 
@@ -29,6 +30,7 @@ func transparentHTTPRules(localPort int, mitmUID uint32, op string) [][]string {
 	uid := strconv.FormatUint(uint64(mitmUID), 10)
 	loopRules := [][]string{
 		{"iptables", "-t", "nat", op, "OUTPUT", "-p", "tcp", "-d", "127.0.0.0/8", "-j", "RETURN"},
+		{"iptables", "-t", "nat", op, "OUTPUT", "-p", "tcp", "-m", "mark", "--mark", constants.MarkHex, "-j", "RETURN"},
 	}
 	redir := [][]string{
 		{

sdks/sandbox/javascript/src/api/egress.ts

@@ -521,11 +521,8 @@ export interface components {
             type: "http";
             /** @description HTTP endpoint URL to fetch the credential from. */
             url: string;
-            /**
-             * @description HTTP method. Defaults to GET.
-             * @default GET
-             */
-            method: string;
+            /** @description HTTP method. Defaults to GET when omitted. */
+            method?: string;
             /** @description Optional static headers sent with the request. */
             headers?: {
                 [key: string]: string;

sdks/sandbox/python/src/opensandbox/api/egress/models/http_credential_source.py

@@ -37,13 +37,13 @@ class HTTPCredentialSource:
     Attributes:
         type_ (HTTPCredentialSourceType):
         url (str): HTTP endpoint URL to fetch the credential from.
-        method (str | Unset): HTTP method. Defaults to GET. Default: 'GET'.
+        method (str | Unset): HTTP method. Defaults to GET when omitted.
         headers (HTTPCredentialSourceHeaders | Unset): Optional static headers sent with the request.
     """
 
     type_: HTTPCredentialSourceType
     url: str
-    method: str | Unset = "GET"
+    method: str | Unset = UNSET
     headers: HTTPCredentialSourceHeaders | Unset = UNSET
 
     def to_dict(self) -> dict[str, Any]:

specs/egress-api.yaml

@@ -554,8 +554,7 @@ components:
           description: HTTP endpoint URL to fetch the credential from.
         method:
           type: string
-          default: GET
-          description: HTTP method. Defaults to GET.
+          description: HTTP method. Defaults to GET when omitted.
         headers:
           type: object
           additionalProperties: