guarddog-nexus/guarddog_nexus/webhooks.py

"""Nexus webhook receiver — handles component/asset webhooks."""

import hashlib
import hmac
import json
import re

from fastapi import APIRouter, BackgroundTasks, Header, HTTPException, Request, status

from guarddog_nexus.config import config
from guarddog_nexus.database import get_session
from guarddog_nexus.harvester import harvest
from guarddog_nexus.logging_setup import log

router = APIRouter(prefix="/webhooks", tags=["webhooks"])

RELEVANT_ACTIONS = {"CREATED", "UPDATED"}

METADATA_PATTERNS = [
    re.compile(p)
    for p in [
        r"^/?simple/",
        r"\.html$",
        r"\.json$",
        r"\.xml$",
        r"/?index\.",
        r"\.rss$",
        r"\.atom$",
    ]
]

PACKAGE_EXTENSIONS = (".tar.gz", ".tgz", ".whl", ".zip", ".gem")


def _is_package_asset(name: str) -> bool:
    for pat in METADATA_PATTERNS:
        if pat.search(name):
            return False
    return name.endswith(PACKAGE_EXTENSIONS)


def _build_download_url(repo: str, asset_path: str) -> str:
    base = config.nexus_url.rstrip("/")
    asset_path = asset_path.lstrip("/")
    return f"{base}/repository/{repo}/{asset_path}"


def _extract_asset_path(asset: dict) -> str | None:
    for key in ("path", "name"):
        val = asset.get(key)
        if val:
            return val
    return None


@router.post("/nexus")
async def nexus_webhook(
    request: Request,
    background_tasks: BackgroundTasks,
    x_nexus_webhook_signature: str | None = Header(None, alias="X-Nexus-Webhook-Signature"),
):
    payload = await request.body()
    payload_str = payload.decode("utf-8")

    if config.webhook_secret:
        if not x_nexus_webhook_signature:
            log.warning("Webhook rejected: missing signature header")
            raise HTTPException(
                status_code=status.HTTP_401_UNAUTHORIZED, detail="Missing signature"
            )
        expected = hmac.new(config.webhook_secret.encode(), payload, hashlib.sha256).hexdigest()
        if not hmac.compare_digest(x_nexus_webhook_signature, expected):
            log.warning("Webhook rejected: invalid signature")
            raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail="Invalid signature")

    try:
        data = json.loads(payload_str)
    except json.JSONDecodeError:
        log.warning("Webhook received invalid JSON")
        raise HTTPException(status_code=status.HTTP_400_BAD_REQUEST, detail="Invalid JSON")

    action = data.get("action", "").upper()
    if action not in RELEVANT_ACTIONS:
        return {"status": "ignored", "action": action}

    repository = data.get("repositoryName", "")

    asset = data.get("asset")
    component = data.get("component")

    if asset:
        asset_path = _extract_asset_path(asset)
        if not asset_path or not _is_package_asset(asset_path):
            return {"status": "ignored", "reason": "non_package_asset"}

        download_url = asset.get("downloadUrl") or _build_download_url(repository, asset_path)

        log.info("Webhook: %s asset %s in %s", action, asset_path, repository)

        background_tasks.add_task(_scan_in_background, download_url, repository, "pypi", asset_path)
        return {"status": "accepted", "asset": asset_path, "action": action}

    if component:
        name = component.get("name", "")
        version = component.get("version", "")
        if not name or not version:
            return {"status": "ignored", "reason": "no_name_or_version"}

        # For component events, look up assets via Nexus REST API
        background_tasks.add_task(_scan_component, repository, name, version)
        return {"status": "accepted", "component": f"{name}=={version}", "action": action}

    return {"status": "ignored", "reason": "no_asset_or_component"}


async def _scan_component(repository: str, name: str, version: str):
    """Look up component assets via Nexus API, then scan each package file."""

    from guarddog_nexus.nexus_client import nexus_get

    api_path = (
        f"/service/rest/v1/search?repository={repository}&name={name}&version={version}&format=pypi"
    )
    try:
        resp = await nexus_get(api_path)
        resp.raise_for_status()
        data = resp.json()
    except Exception as e:
        log.warning("Component lookup error for %s==%s: %s", name, version, e)
        return

    items = data.get("items", [])
    if not items:
        log.warning("No items found in search for %s==%s", name, version)
        return

    for item in items:
        for asset in item.get("assets", []):
            asset_path = _extract_asset_path(asset)
            if not asset_path or not _is_package_asset(asset_path):
                continue
            download_url = asset.get("downloadUrl") or _build_download_url(repository, asset_path)
            log.info("Scanning component asset: %s", asset_path)
            async for session in get_session():
                await harvest(download_url, repository, "pypi", asset_path, session)
                break


async def _scan_in_background(
    download_url: str,
    repository: str,
    format_: str,
    asset_path: str,
):
    try:
        async for session in get_session():
            await harvest(download_url, repository, format_, asset_path, session)
            break
    except Exception as e:
        log.error("Background scan failed: %s", e)