feat: enable container access to host localhost services

Rewrite localhost/127.x.x.x/0.0.0.0 target URLs to use host.docker.internal,
allowing the container to reach services running on the host machine.

- Add extra_hosts mapping for host.docker.internal on Linux
- Add HOST_GATEWAY env var to container
- Add rewrite_localhost_targets() to transform localhost URLs
- Support full 127.0.0.0/8 loopback range and IPv6 ::1

strix/interface/main.py

@@ -30,9 +30,10 @@ from strix.interface.utils import (
     image_exists,
     infer_target_type,
     process_pull_line,
+    rewrite_localhost_targets,
     validate_llm_response,
 )
-from strix.runtime.docker_runtime import STRIX_IMAGE
+from strix.runtime.docker_runtime import HOST_GATEWAY_HOSTNAME, STRIX_IMAGE
 from strix.telemetry.tracer import get_global_tracer
 
 
@@ -377,6 +378,7 @@ Examples:
             parser.error(f"Invalid target '{target}'")
 
     assign_workspace_subdirs(args.targets_info)
+    rewrite_localhost_targets(args.targets_info, HOST_GATEWAY_HOSTNAME)
 
     return args
 

strix/interface/utils.py

@@ -404,6 +404,47 @@ def collect_local_sources(targets_info: list[dict[str, Any]]) -> list[dict[str,
     return local_sources
 
 
+def _is_localhost_host(host: str) -> bool:
+    host_lower = host.lower().strip("[]")
+
+    if host_lower in ("localhost", "0.0.0.0", "::1"):  # nosec B104
+        return True
+
+    try:
+        ip = ipaddress.ip_address(host_lower)
+        if isinstance(ip, ipaddress.IPv4Address):
+            return ip.is_loopback  # 127.0.0.0/8
+        if isinstance(ip, ipaddress.IPv6Address):
+            return ip.is_loopback  # ::1
+    except ValueError:
+        pass
+
+    return False
+
+
+def rewrite_localhost_targets(targets_info: list[dict[str, Any]], host_gateway: str) -> None:
+    from yarl import URL  # type: ignore[import-not-found]
+
+    for target_info in targets_info:
+        target_type = target_info.get("type")
+        details = target_info.get("details", {})
+
+        if target_type == "web_application":
+            target_url = details.get("target_url", "")
+            try:
+                url = URL(target_url)
+            except (ValueError, TypeError):
+                continue
+
+            if url.host and _is_localhost_host(url.host):
+                details["target_url"] = str(url.with_host(host_gateway))
+
+        elif target_type == "ip_address":
+            target_ip = details.get("target_ip", "")
+            if target_ip and _is_localhost_host(target_ip):
+                details["target_ip"] = host_gateway
+
+
 # Repository utilities
 def clone_repository(repo_url: str, run_name: str, dest_name: str | None = None) -> str:
     console = Console()

strix/runtime/docker_runtime.py

@@ -15,6 +15,7 @@ from .runtime import AbstractRuntime, SandboxInfo
 
 
 STRIX_IMAGE = os.getenv("STRIX_IMAGE", "ghcr.io/usestrix/strix-sandbox:0.1.10")
+HOST_GATEWAY_HOSTNAME = "host.docker.internal"
 logger = logging.getLogger(__name__)
 
 
@@ -121,7 +122,9 @@ class DockerRuntime(AbstractRuntime):
                         "CAIDO_PORT": str(caido_port),
                         "TOOL_SERVER_PORT": str(tool_server_port),
                         "TOOL_SERVER_TOKEN": tool_server_token,
+                        "HOST_GATEWAY": HOST_GATEWAY_HOSTNAME,
                     },
+                    extra_hosts=self._get_extra_hosts(),
                     tty=True,
                 )
 
@@ -381,6 +384,9 @@ class DockerRuntime(AbstractRuntime):
 
         return "127.0.0.1"
 
+    def _get_extra_hosts(self) -> dict[str, str]:
+        return {HOST_GATEWAY_HOSTNAME: "host-gateway"}
+
     async def destroy_sandbox(self, container_id: str) -> None:
         logger.info("Destroying scan container %s", container_id)
         try: