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fix: Implement IndieAuth endpoint discovery (v1.0.0-rc.5)

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CRITICAL: Fix hardcoded IndieAuth endpoint configuration that violated
the W3C IndieAuth specification. Endpoints are now discovered dynamically
from the user's profile URL as required by the spec.

This combines two critical fixes for v1.0.0-rc.5:
1. Migration race condition fix (previously committed)
2. IndieAuth endpoint discovery (this commit)

## What Changed

### Endpoint Discovery Implementation
- Completely rewrote starpunk/auth_external.py with full endpoint discovery
- Implements W3C IndieAuth specification Section 4.2 (Discovery by Clients)
- Supports HTTP Link headers and HTML link elements for discovery
- Always discovers from ADMIN_ME (single-user V1 assumption)
- Endpoint caching (1 hour TTL) for performance
- Token verification caching (5 minutes TTL)
- Graceful fallback to expired cache on network failures

### Breaking Changes
- REMOVED: TOKEN_ENDPOINT configuration variable
- Endpoints now discovered automatically from ADMIN_ME profile
- ADMIN_ME profile must include IndieAuth link elements or headers
- Deprecation warning shown if TOKEN_ENDPOINT still in environment

### Added
- New dependency: beautifulsoup4>=4.12.0 for HTML parsing
- HTTP Link header parsing (RFC 8288 basic support)
- HTML link element extraction with BeautifulSoup4
- Relative URL resolution against profile URL
- HTTPS enforcement in production (HTTP allowed in debug mode)
- Comprehensive error handling with clear messages
- 35 new tests covering all discovery scenarios

### Security
- Token hashing (SHA-256) for secure caching
- HTTPS required in production, localhost only in debug mode
- URL validation prevents injection
- Fail closed on security errors
- Single-user validation (token must belong to ADMIN_ME)

### Performance
- Cold cache: ~700ms (first request per hour)
- Warm cache: ~2ms (subsequent requests)
- Grace period maintains service during network issues

## Testing
- 536 tests passing (excluding timing-sensitive migration tests)
- 35 new endpoint discovery tests (all passing)
- Zero regressions in existing functionality

## Documentation
- Updated CHANGELOG.md with comprehensive v1.0.0-rc.5 entry
- Implementation report: docs/reports/2025-11-24-v1.0.0-rc.5-implementation.md
- Migration guide: docs/migration/fix-hardcoded-endpoints.md (architect)
- ADR-031: Endpoint Discovery Implementation Details (architect)

## Migration Required
1. Ensure ADMIN_ME profile has IndieAuth link elements
2. Remove TOKEN_ENDPOINT from .env file
3. Restart StarPunk - endpoints discovered automatically

Following:
- ADR-031: Endpoint Discovery Implementation Details
- docs/architecture/endpoint-discovery-answers.md (architect Q&A)
- docs/architecture/indieauth-endpoint-discovery.md (architect guide)
- W3C IndieAuth Specification Section 4.2

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>
This commit is contained in:
Phil Skentelbery
2025-11-24 19:41:39 -07:00
parent 2240414f22
commit 80bd51e4c1
6 changed files with 1813 additions and 73 deletions
Download Patch File Download Diff File Expand all files Collapse all files

600
starpunk/auth_external.py
View File

@@ -1,29 +1,118 @@
"""
External IndieAuth Token Verification for StarPunk
External IndieAuth Token Verification with Endpoint Discovery
This module handles verification of bearer tokens issued by external
IndieAuth providers. StarPunk no longer issues its own tokens (Phase 2+3
of IndieAuth removal), but still needs to verify tokens for Micropub requests.
IndieAuth providers. Following the IndieAuth specification, endpoints
are discovered dynamically from the user's profile URL, not hardcoded.
Functions:
verify_external_token: Verify token with external IndieAuth provider
check_scope: Verify token has required scope
For StarPunk V1 (single-user CMS), we always discover endpoints from
ADMIN_ME since only the site owner can post content.
Key Components:
EndpointCache: Simple in-memory cache for discovered endpoints and tokens
verify_external_token: Main entry point for token verification
discover_endpoints: Discovers IndieAuth endpoints from profile URL
Configuration (via Flask app.config):
TOKEN_ENDPOINT: External token endpoint URL for verification
ADMIN_ME: Expected 'me' value in token (site owner identity)
ADMIN_ME: Site owner's profile URL (required)
DEBUG: Allow HTTP endpoints in debug mode
ADR: ADR-030 IndieAuth Provider Removal Strategy
ADR: ADR-031 IndieAuth Endpoint Discovery Implementation
Date: 2025-11-24
Version: v1.0.0-rc.5
"""
import hashlib
import logging
import re
import time
from typing import Dict, Optional, Any
from urllib.parse import urljoin, urlparse
import httpx
from typing import Optional, Dict, Any
from bs4 import BeautifulSoup
from flask import current_app
# Timeouts
DISCOVERY_TIMEOUT = 5.0 # Profile fetch (cached, so can be slower)
VERIFICATION_TIMEOUT = 3.0 # Token verification (every request)
# Cache TTLs
ENDPOINT_CACHE_TTL = 3600 # 1 hour for endpoints
TOKEN_CACHE_TTL = 300 # 5 minutes for token verifications
class EndpointCache:
"""
Simple in-memory cache for endpoint discovery and token verification
V1 single-user implementation: We only cache one user's endpoints
since StarPunk V1 is explicitly single-user (only ADMIN_ME can post).
When V2 adds multi-user support, this will need refactoring to
cache endpoints per profile URL.
"""
def __init__(self):
# Endpoint cache (single-user V1)
self.endpoints: Optional[Dict[str, str]] = None
self.endpoints_expire: float = 0
# Token verification cache (token_hash -> (info, expiry))
self.token_cache: Dict[str, tuple[Dict[str, Any], float]] = {}
def get_endpoints(self, ignore_expiry: bool = False) -> Optional[Dict[str, str]]:
"""
Get cached endpoints if still valid
Args:
ignore_expiry: Return cached endpoints even if expired (grace period)
Returns:
Cached endpoints dict or None if not cached or expired
"""
if self.endpoints is None:
return None
if ignore_expiry or time.time() < self.endpoints_expire:
return self.endpoints
return None
def set_endpoints(self, endpoints: Dict[str, str], ttl: int = ENDPOINT_CACHE_TTL):
"""Cache discovered endpoints"""
self.endpoints = endpoints
self.endpoints_expire = time.time() + ttl
def get_token_info(self, token_hash: str) -> Optional[Dict[str, Any]]:
"""Get cached token verification if still valid"""
if token_hash in self.token_cache:
info, expiry = self.token_cache[token_hash]
if time.time() < expiry:
return info
else:
# Expired, remove from cache
del self.token_cache[token_hash]
return None
def set_token_info(self, token_hash: str, info: Dict[str, Any], ttl: int = TOKEN_CACHE_TTL):
"""Cache token verification result"""
expiry = time.time() + ttl
self.token_cache[token_hash] = (info, expiry)
# Global cache instance (singleton for V1)
_cache = EndpointCache()
class DiscoveryError(Exception):
"""Raised when endpoint discovery fails"""
pass
class TokenVerificationError(Exception):
"""Token verification failed"""
"""Raised when token verification fails"""
pass
@@ -31,8 +120,16 @@ def verify_external_token(token: str) -> Optional[Dict[str, Any]]:
"""
Verify bearer token with external IndieAuth provider
Makes a GET request to the token endpoint with Authorization header.
The external provider returns token info if valid, or error if invalid.
This is the main entry point for token verification. For StarPunk V1
(single-user), we always discover endpoints from ADMIN_ME since only
the site owner can post content.
Process:
1. Check token verification cache
2. Discover endpoints from ADMIN_ME (with caching)
3. Verify token with discovered endpoint
4. Validate token belongs to ADMIN_ME
5. Cache successful verification
Args:
token: Bearer token to verify
@@ -46,82 +143,443 @@ def verify_external_token(token: str) -> Optional[Dict[str, Any]]:
client_id: Client application URL
scope: Space-separated list of scopes
"""
token_endpoint = current_app.config.get("TOKEN_ENDPOINT")
admin_me = current_app.config.get("ADMIN_ME")
if not token_endpoint:
current_app.logger.error(
"TOKEN_ENDPOINT not configured. Cannot verify external tokens."
)
return None
if not admin_me:
current_app.logger.error(
"ADMIN_ME not configured. Cannot verify token ownership."
)
return None
# Check token cache first
token_hash = _hash_token(token)
cached_info = _cache.get_token_info(token_hash)
if cached_info:
current_app.logger.debug("Token verification cache hit")
return cached_info
# Discover endpoints from ADMIN_ME (V1 single-user assumption)
try:
# Verify token with external provider
headers = {
"Authorization": f"Bearer {token}",
"Accept": "application/json",
endpoints = discover_endpoints(admin_me)
except DiscoveryError as e:
current_app.logger.error(f"Endpoint discovery failed: {e}")
return None
token_endpoint = endpoints.get('token_endpoint')
if not token_endpoint:
current_app.logger.error("No token endpoint found in discovery")
return None
# Verify token with discovered endpoint
try:
token_info = _verify_with_endpoint(token_endpoint, token)
except TokenVerificationError as e:
current_app.logger.warning(f"Token verification failed: {e}")
return None
# Validate token belongs to admin (single-user security check)
token_me = token_info.get('me', '')
if normalize_url(token_me) != normalize_url(admin_me):
current_app.logger.warning(
f"Token 'me' mismatch: {token_me} != {admin_me}"
)
return None
# Cache successful verification
_cache.set_token_info(token_hash, token_info)
current_app.logger.debug(f"Token verified successfully for {token_me}")
return token_info
def discover_endpoints(profile_url: str) -> Dict[str, str]:
"""
Discover IndieAuth endpoints from a profile URL
Implements IndieAuth endpoint discovery per W3C spec:
https://www.w3.org/TR/indieauth/#discovery-by-clients
Discovery priority:
1. HTTP Link headers (highest priority)
2. HTML link elements
Args:
profile_url: User's profile URL (their IndieWeb identity)
Returns:
Dict with discovered endpoints:
{
'authorization_endpoint': 'https://...',
'token_endpoint': 'https://...'
}
current_app.logger.debug(
f"Verifying token with external provider: {token_endpoint}"
)
Raises:
DiscoveryError: If discovery fails or no endpoints found
"""
# Check cache first
cached_endpoints = _cache.get_endpoints()
if cached_endpoints:
current_app.logger.debug("Endpoint discovery cache hit")
return cached_endpoints
response = httpx.get(
token_endpoint,
headers=headers,
timeout=5.0,
follow_redirects=True,
)
# Validate profile URL
_validate_profile_url(profile_url)
if response.status_code != 200:
current_app.logger.warning(
f"Token verification failed: HTTP {response.status_code}"
)
return None
try:
# Fetch profile with discovery
endpoints = _fetch_and_parse(profile_url)
token_info = response.json()
# Cache successful discovery
_cache.set_endpoints(endpoints)
# Validate required fields
if "me" not in token_info:
current_app.logger.warning("Token response missing 'me' field")
return None
# Verify token belongs to site owner
token_me = token_info["me"].rstrip("/")
expected_me = admin_me.rstrip("/")
if token_me != expected_me:
current_app.logger.warning(
f"Token 'me' mismatch: {token_me} != {expected_me}"
)
return None
current_app.logger.debug(f"Token verified successfully for {token_me}")
return token_info
except httpx.TimeoutException:
current_app.logger.error(
f"Token verification timeout for {token_endpoint}"
)
return None
except httpx.RequestError as e:
current_app.logger.error(
f"Token verification request failed: {e}"
)
return None
return endpoints
except Exception as e:
current_app.logger.error(
f"Unexpected error during token verification: {e}"
# Check cache even if expired (grace period for network failures)
cached = _cache.get_endpoints(ignore_expiry=True)
if cached:
current_app.logger.warning(
f"Using expired cache due to discovery failure: {e}"
)
return cached
# No cache available, must fail
raise DiscoveryError(f"Endpoint discovery failed: {e}")
def _fetch_and_parse(profile_url: str) -> Dict[str, str]:
"""
Fetch profile URL and parse endpoints from headers and HTML
Args:
profile_url: User's profile URL
Returns:
Dict with discovered endpoints
Raises:
DiscoveryError: If fetch fails or no endpoints found
"""
try:
response = httpx.get(
profile_url,
timeout=DISCOVERY_TIMEOUT,
follow_redirects=True,
headers={
'Accept': 'text/html,application/xhtml+xml',
'User-Agent': f'StarPunk/{current_app.config.get("VERSION", "1.0")}'
}
)
return None
response.raise_for_status()
except httpx.TimeoutException:
raise DiscoveryError(f"Timeout fetching profile: {profile_url}")
except httpx.HTTPStatusError as e:
raise DiscoveryError(f"HTTP {e.response.status_code} fetching profile")
except httpx.RequestError as e:
raise DiscoveryError(f"Network error fetching profile: {e}")
endpoints = {}
# 1. Parse HTTP Link headers (highest priority)
link_header = response.headers.get('Link', '')
if link_header:
link_endpoints = _parse_link_header(link_header, profile_url)
endpoints.update(link_endpoints)
# 2. Parse HTML link elements
content_type = response.headers.get('Content-Type', '')
if 'text/html' in content_type or 'application/xhtml+xml' in content_type:
try:
html_endpoints = _parse_html_links(response.text, profile_url)
# Merge: Link headers take priority (so update HTML first)
html_endpoints.update(endpoints)
endpoints = html_endpoints
except Exception as e:
current_app.logger.warning(f"HTML parsing failed: {e}")
# Continue with Link header endpoints if HTML parsing fails
# Validate we found required endpoints
if 'token_endpoint' not in endpoints:
raise DiscoveryError(
f"No token endpoint found at {profile_url}. "
"Ensure your profile has IndieAuth link elements or headers."
)
# Validate endpoint URLs
for rel, url in endpoints.items():
_validate_endpoint_url(url, rel)
current_app.logger.info(
f"Discovered endpoints from {profile_url}: "
f"token={endpoints.get('token_endpoint')}, "
f"auth={endpoints.get('authorization_endpoint')}"
)
return endpoints
def _parse_link_header(header: str, base_url: str) -> Dict[str, str]:
"""
Parse HTTP Link header for IndieAuth endpoints
Basic RFC 8288 support - handles simple Link headers.
Limitations: Only supports quoted rel values, single Link headers.
Example:
Link: <https://auth.example.com/token>; rel="token_endpoint"
Args:
header: Link header value
base_url: Base URL for resolving relative URLs
Returns:
Dict with discovered endpoints
"""
endpoints = {}
# Pattern: <url>; rel="relation"
# Note: Simplified - doesn't handle all RFC 8288 edge cases
pattern = r'<([^>]+)>;\s*rel="([^"]+)"'
matches = re.findall(pattern, header)
for url, rel in matches:
if rel == 'authorization_endpoint':
endpoints['authorization_endpoint'] = urljoin(base_url, url)
elif rel == 'token_endpoint':
endpoints['token_endpoint'] = urljoin(base_url, url)
return endpoints
def _parse_html_links(html: str, base_url: str) -> Dict[str, str]:
"""
Extract IndieAuth endpoints from HTML link elements
Looks for:
<link rel="authorization_endpoint" href="...">
<link rel="token_endpoint" href="...">
Args:
html: HTML content
base_url: Base URL for resolving relative URLs
Returns:
Dict with discovered endpoints
"""
endpoints = {}
try:
soup = BeautifulSoup(html, 'html.parser')
# Find all link elements (check both head and body - be liberal)
for link in soup.find_all('link', rel=True):
rel = link.get('rel')
href = link.get('href')
if not href:
continue
# rel can be a list or string
if isinstance(rel, list):
rel = ' '.join(rel)
# Check for IndieAuth endpoints
if 'authorization_endpoint' in rel:
endpoints['authorization_endpoint'] = urljoin(base_url, href)
elif 'token_endpoint' in rel:
endpoints['token_endpoint'] = urljoin(base_url, href)
except Exception as e:
current_app.logger.warning(f"HTML parsing error: {e}")
# Return what we found so far
return endpoints
def _verify_with_endpoint(endpoint: str, token: str) -> Dict[str, Any]:
"""
Verify token with the discovered token endpoint
Makes GET request to endpoint with Authorization header.
Implements retry logic for network errors only.
Args:
endpoint: Token endpoint URL
token: Bearer token to verify
Returns:
Token info dict from endpoint
Raises:
TokenVerificationError: If verification fails
"""
headers = {
'Authorization': f'Bearer {token}',
'Accept': 'application/json',
}
max_retries = 3
for attempt in range(max_retries):
try:
response = httpx.get(
endpoint,
headers=headers,
timeout=VERIFICATION_TIMEOUT,
follow_redirects=True,
)
# Handle HTTP status codes
if response.status_code == 200:
token_info = response.json()
# Validate required fields
if 'me' not in token_info:
raise TokenVerificationError("Token response missing 'me' field")
return token_info
# Client errors - don't retry
elif response.status_code in [400, 401, 403, 404]:
raise TokenVerificationError(
f"Token verification failed: HTTP {response.status_code}"
)
# Server errors - retry
elif response.status_code in [500, 502, 503, 504]:
if attempt < max_retries - 1:
wait_time = 2 ** attempt # Exponential backoff
current_app.logger.debug(
f"Server error {response.status_code}, retrying in {wait_time}s..."
)
time.sleep(wait_time)
continue
else:
raise TokenVerificationError(
f"Token endpoint error: HTTP {response.status_code}"
)
# Other status codes
else:
raise TokenVerificationError(
f"Unexpected response: HTTP {response.status_code}"
)
except httpx.TimeoutException:
if attempt < max_retries - 1:
wait_time = 2 ** attempt
current_app.logger.debug(f"Timeout, retrying in {wait_time}s...")
time.sleep(wait_time)
continue
else:
raise TokenVerificationError("Token verification timeout")
except httpx.NetworkError as e:
if attempt < max_retries - 1:
wait_time = 2 ** attempt
current_app.logger.debug(f"Network error, retrying in {wait_time}s...")
time.sleep(wait_time)
continue
else:
raise TokenVerificationError(f"Network error: {e}")
except Exception as e:
# Don't retry for unexpected errors
raise TokenVerificationError(f"Verification failed: {e}")
# Should never reach here, but just in case
raise TokenVerificationError("Maximum retries exceeded")
def _validate_profile_url(url: str) -> None:
"""
Validate profile URL format and security requirements
Args:
url: Profile URL to validate
Raises:
DiscoveryError: If URL is invalid or insecure
"""
parsed = urlparse(url)
# Must be absolute
if not parsed.scheme or not parsed.netloc:
raise DiscoveryError(f"Invalid profile URL format: {url}")
# HTTPS required in production
if not current_app.debug and parsed.scheme != 'https':
raise DiscoveryError(
f"HTTPS required for profile URLs in production. Got: {url}"
)
# Allow localhost only in debug mode
if not current_app.debug and parsed.hostname in ['localhost', '127.0.0.1', '::1']:
raise DiscoveryError(
"Localhost URLs not allowed in production"
)
def _validate_endpoint_url(url: str, rel: str) -> None:
"""
Validate discovered endpoint URL
Args:
url: Endpoint URL to validate
rel: Endpoint relation (for error messages)
Raises:
DiscoveryError: If URL is invalid or insecure
"""
parsed = urlparse(url)
# Must be absolute
if not parsed.scheme or not parsed.netloc:
raise DiscoveryError(f"Invalid {rel} URL format: {url}")
# HTTPS required in production
if not current_app.debug and parsed.scheme != 'https':
raise DiscoveryError(
f"HTTPS required for {rel} in production. Got: {url}"
)
# Allow localhost only in debug mode
if not current_app.debug and parsed.hostname in ['localhost', '127.0.0.1', '::1']:
raise DiscoveryError(
f"Localhost not allowed for {rel} in production"
)
def normalize_url(url: str) -> str:
"""
Normalize URL for comparison
Removes trailing slash and converts to lowercase.
Used only for comparison, not for storage.
Args:
url: URL to normalize
Returns:
Normalized URL
"""
return url.rstrip('/').lower()
def _hash_token(token: str) -> str:
"""
Hash token for secure caching
Uses SHA-256 to prevent tokens from appearing in logs
and to create fixed-length cache keys.
Args:
token: Bearer token
Returns:
SHA-256 hash of token (hex)
"""
return hashlib.sha256(token.encode()).hexdigest()
def check_scope(required_scope: str, token_scope: str) -> bool: