"""Tests for StreamableHTTP server DNS rebinding protection."""
import logging
import multiprocessing
import socket
import time
from collections.abc import AsyncGenerator
from contextlib import asynccontextmanager
import httpx
import pytest
import uvicorn
from starlette.applications import Starlette
from starlette.routing import Mount
from starlette.types import Receive, Scope, Send
from mcp.server import Server
from mcp.server.streamable_http_manager import StreamableHTTPSessionManager
from mcp.server.transport_security import TransportSecuritySettings
from mcp.types import Tool
logger = logging.getLogger(__name__)
SERVER_NAME = "test_streamable_http_security_server"
@pytest.fixture
def server_port() -> int:
with socket.socket() as s:
s.bind(("127.0.0.1", 0))
return s.getsockname()[1]
@pytest.fixture
def server_url(server_port: int) -> str:
return f"http://127.0.0.1:{server_port}"
class SecurityTestServer(Server):
def __init__(self):
super().__init__(SERVER_NAME)
async def on_list_tools(self) -> list[Tool]:
return []
def run_server_with_settings(port: int, security_settings: TransportSecuritySettings | None = None):
"""Run the StreamableHTTP server with specified security settings."""
app = SecurityTestServer()
# Create session manager with security settings
session_manager = StreamableHTTPSessionManager(
app=app,
json_response=False,
stateless=False,
security_settings=security_settings,
)
# Create the ASGI handler
async def handle_streamable_http(scope: Scope, receive: Receive, send: Send) -> None:
await session_manager.handle_request(scope, receive, send)
# Create Starlette app with lifespan
@asynccontextmanager
async def lifespan(app: Starlette) -> AsyncGenerator[None, None]:
async with session_manager.run():
yield
routes = [
Mount("/", app=handle_streamable_http),
]
starlette_app = Starlette(routes=routes, lifespan=lifespan)
uvicorn.run(starlette_app, host="127.0.0.1", port=port, log_level="error")
def start_server_process(port: int, security_settings: TransportSecuritySettings | None = None):
"""Start server in a separate process."""
process = multiprocessing.Process(target=run_server_with_settings, args=(port, security_settings))
process.start()
# Give server time to start
time.sleep(1)
return process
@pytest.mark.anyio
async def test_streamable_http_security_default_settings(server_port: int):
"""Test StreamableHTTP with default security settings (protection enabled)."""
process = start_server_process(server_port)
try:
# Test with valid localhost headers
async with httpx.AsyncClient(timeout=5.0) as client:
# POST request to initialize session
response = await client.post(
f"http://127.0.0.1:{server_port}/",
json={"jsonrpc": "2.0", "method": "initialize", "id": 1, "params": {}},
headers={
"Accept": "application/json, text/event-stream",
"Content-Type": "application/json",
},
)
assert response.status_code == 200
assert "mcp-session-id" in response.headers
finally:
process.terminate()
process.join()
@pytest.mark.anyio
async def test_streamable_http_security_invalid_host_header(server_port: int):
"""Test StreamableHTTP with invalid Host header."""
security_settings = TransportSecuritySettings(enable_dns_rebinding_protection=True)
process = start_server_process(server_port, security_settings)
try:
# Test with invalid host header
headers = {
"Host": "evil.com",
"Accept": "application/json, text/event-stream",
"Content-Type": "application/json",
}
async with httpx.AsyncClient(timeout=5.0) as client:
response = await client.post(
f"http://127.0.0.1:{server_port}/",
json={"jsonrpc": "2.0", "method": "initialize", "id": 1, "params": {}},
headers=headers,
)
assert response.status_code == 421
assert response.text == "Invalid Host header"
finally:
process.terminate()
process.join()
@pytest.mark.anyio
async def test_streamable_http_security_invalid_origin_header(server_port: int):
"""Test StreamableHTTP with invalid Origin header."""
security_settings = TransportSecuritySettings(enable_dns_rebinding_protection=True, allowed_hosts=["127.0.0.1:*"])
process = start_server_process(server_port, security_settings)
try:
# Test with invalid origin header
headers = {
"Origin": "http://evil.com",
"Accept": "application/json, text/event-stream",
"Content-Type": "application/json",
}
async with httpx.AsyncClient(timeout=5.0) as client:
response = await client.post(
f"http://127.0.0.1:{server_port}/",
json={"jsonrpc": "2.0", "method": "initialize", "id": 1, "params": {}},
headers=headers,
)
assert response.status_code == 400
assert response.text == "Invalid Origin header"
finally:
process.terminate()
process.join()
@pytest.mark.anyio
async def test_streamable_http_security_invalid_content_type(server_port: int):
"""Test StreamableHTTP POST with invalid Content-Type header."""
process = start_server_process(server_port)
try:
async with httpx.AsyncClient(timeout=5.0) as client:
# Test POST with invalid content type
response = await client.post(
f"http://127.0.0.1:{server_port}/",
headers={
"Content-Type": "text/plain",
"Accept": "application/json, text/event-stream",
},
content="test",
)
assert response.status_code == 400
assert response.text == "Invalid Content-Type header"
# Test POST with missing content type
response = await client.post(
f"http://127.0.0.1:{server_port}/",
headers={"Accept": "application/json, text/event-stream"},
content="test",
)
assert response.status_code == 400
assert response.text == "Invalid Content-Type header"
finally:
process.terminate()
process.join()
@pytest.mark.anyio
async def test_streamable_http_security_disabled(server_port: int):
"""Test StreamableHTTP with security disabled."""
settings = TransportSecuritySettings(enable_dns_rebinding_protection=False)
process = start_server_process(server_port, settings)
try:
# Test with invalid host header - should still work
headers = {
"Host": "evil.com",
"Accept": "application/json, text/event-stream",
"Content-Type": "application/json",
}
async with httpx.AsyncClient(timeout=5.0) as client:
response = await client.post(
f"http://127.0.0.1:{server_port}/",
json={"jsonrpc": "2.0", "method": "initialize", "id": 1, "params": {}},
headers=headers,
)
# Should connect successfully even with invalid host
assert response.status_code == 200
finally:
process.terminate()
process.join()
@pytest.mark.anyio
async def test_streamable_http_security_custom_allowed_hosts(server_port: int):
"""Test StreamableHTTP with custom allowed hosts."""
settings = TransportSecuritySettings(
enable_dns_rebinding_protection=True,
allowed_hosts=["localhost", "127.0.0.1", "custom.host"],
allowed_origins=["http://localhost", "http://127.0.0.1", "http://custom.host"],
)
process = start_server_process(server_port, settings)
try:
# Test with custom allowed host
headers = {
"Host": "custom.host",
"Accept": "application/json, text/event-stream",
"Content-Type": "application/json",
}
async with httpx.AsyncClient(timeout=5.0) as client:
response = await client.post(
f"http://127.0.0.1:{server_port}/",
json={"jsonrpc": "2.0", "method": "initialize", "id": 1, "params": {}},
headers=headers,
)
# Should connect successfully with custom host
assert response.status_code == 200
finally:
process.terminate()
process.join()
@pytest.mark.anyio
async def test_streamable_http_security_get_request(server_port: int):
"""Test StreamableHTTP GET request with security."""
security_settings = TransportSecuritySettings(enable_dns_rebinding_protection=True, allowed_hosts=["127.0.0.1"])
process = start_server_process(server_port, security_settings)
try:
# Test GET request with invalid host header
headers = {
"Host": "evil.com",
"Accept": "text/event-stream",
}
async with httpx.AsyncClient(timeout=5.0) as client:
response = await client.get(f"http://127.0.0.1:{server_port}/", headers=headers)
assert response.status_code == 421
assert response.text == "Invalid Host header"
# Test GET request with valid host header
headers = {
"Host": "127.0.0.1",
"Accept": "text/event-stream",
}
async with httpx.AsyncClient(timeout=5.0) as client:
# GET requests need a session ID in StreamableHTTP
# So it will fail with "Missing session ID" not security error
response = await client.get(f"http://127.0.0.1:{server_port}/", headers=headers)
# This should pass security but fail on session validation
assert response.status_code == 400
body = response.json()
assert "Missing session ID" in body["error"]["message"]
finally:
process.terminate()
process.join()
