feat(phase-3): implement token endpoint and OAuth 2.0 flow
Phase 3 Implementation: - Token service with secure token generation and validation - Token endpoint (POST /token) with OAuth 2.0 compliance - Database migration 003 for tokens table - Authorization code validation and single-use enforcement Phase 1 Updates: - Enhanced CodeStore to support dict values with JSON serialization - Maintains backward compatibility Phase 2 Updates: - Authorization codes now include PKCE fields, used flag, timestamps - Complete metadata structure for token exchange Security: - 256-bit cryptographically secure tokens (secrets.token_urlsafe) - SHA-256 hashed storage (no plaintext) - Constant-time comparison for validation - Single-use code enforcement with replay detection Testing: - 226 tests passing (100%) - 87.27% coverage (exceeds 80% requirement) - OAuth 2.0 compliance verified This completes the v1.0.0 MVP with full IndieAuth authorization code flow. 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude <noreply@anthropic.com>
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src/gondulf/services/token_service.py
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274
src/gondulf/services/token_service.py
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"""
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Token service for access token generation and validation.
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Implements opaque token strategy per ADR-004:
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- Tokens are cryptographically random strings
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- Tokens are stored as SHA-256 hashes in database
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- Tokens contain no user information (opaque)
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- Tokens are validated via database lookup
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"""
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import hashlib
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import logging
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import secrets
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from datetime import datetime, timedelta
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from typing import Optional
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from sqlalchemy import text
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from gondulf.database.connection import Database
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logger = logging.getLogger("gondulf.token_service")
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class TokenService:
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"""
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Service for access token generation and validation.
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Implements opaque token strategy per ADR-004:
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- Tokens are cryptographically random strings
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- Tokens are stored as SHA-256 hashes in database
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- Tokens contain no user information (opaque)
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- Tokens are validated via database lookup
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"""
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def __init__(
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self,
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database: Database,
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token_length: int = 32, # 32 bytes = 256 bits
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token_ttl: int = 3600 # 1 hour in seconds
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):
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"""
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Initialize token service.
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Args:
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database: Database instance from Phase 1
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token_length: Token length in bytes (default: 32 = 256 bits)
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token_ttl: Token time-to-live in seconds (default: 3600 = 1 hour)
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"""
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self.database = database
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self.token_length = token_length
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self.token_ttl = token_ttl
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logger.debug(
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f"TokenService initialized with token_length={token_length}, "
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f"token_ttl={token_ttl}s"
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)
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def generate_token(
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self,
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me: str,
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client_id: str,
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scope: str = ""
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) -> str:
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"""
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Generate opaque access token and store in database.
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Token generation:
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1. Generate cryptographically secure random string (256 bits)
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2. Hash token with SHA-256 for storage
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3. Store hash + metadata in database
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4. Return plaintext token to caller (only time it exists in plaintext)
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Args:
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me: User's domain URL (e.g., "https://example.com")
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client_id: Client application URL
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scope: Requested scopes (empty string for v1.0.0 authentication)
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Returns:
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Opaque access token (43-character base64url string)
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Raises:
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DatabaseError: If database operations fail
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"""
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# SECURITY: Generate cryptographically secure token (256 bits)
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token = secrets.token_urlsafe(self.token_length) # 32 bytes = 43-char base64url
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# SECURITY: Hash token for storage (prevent recovery from database)
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token_hash = hashlib.sha256(token.encode('utf-8')).hexdigest()
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# Calculate expiration timestamp
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issued_at = datetime.utcnow()
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expires_at = issued_at + timedelta(seconds=self.token_ttl)
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# Store token metadata in database
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engine = self.database.get_engine()
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with engine.begin() as conn:
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conn.execute(
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text("""
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INSERT INTO tokens (token_hash, me, client_id, scope, issued_at, expires_at, revoked)
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VALUES (:token_hash, :me, :client_id, :scope, :issued_at, :expires_at, 0)
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"""),
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{
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"token_hash": token_hash,
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"me": me,
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"client_id": client_id,
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"scope": scope,
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"issued_at": issued_at,
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"expires_at": expires_at
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}
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)
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# PRIVACY: Log token generation without revealing full token
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logger.info(
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f"Token generated for {me} (client: {client_id}, "
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f"prefix: {token[:8]}..., expires: {expires_at.isoformat()})"
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)
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return token # Return plaintext token (only time it exists in plaintext)
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def validate_token(self, provided_token: str) -> Optional[dict[str, str]]:
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"""
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Validate access token and return metadata.
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Validation steps:
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1. Hash provided token with SHA-256
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2. Lookup hash in database (constant-time comparison)
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3. Check expiration (database timestamp vs current time)
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4. Check revocation flag
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5. Return metadata if valid, None if invalid
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Args:
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provided_token: Access token from Authorization header
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Returns:
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Token metadata dict if valid: {me, client_id, scope}
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None if invalid (not found, expired, or revoked)
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Raises:
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No exceptions raised - returns None for all error cases
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"""
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try:
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# SECURITY: Hash provided token for constant-time comparison
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token_hash = hashlib.sha256(provided_token.encode('utf-8')).hexdigest()
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# Lookup token in database
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engine = self.database.get_engine()
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with engine.connect() as conn:
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result = conn.execute(
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text("""
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SELECT me, client_id, scope, expires_at, revoked
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FROM tokens
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WHERE token_hash = :token_hash
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"""),
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{"token_hash": token_hash}
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).fetchone()
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# Token not found
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if not result:
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logger.warning(f"Token validation failed: not found (prefix: {provided_token[:8]}...)")
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return None
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# Convert Row to dict
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token_data = dict(result._mapping)
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# Check expiration
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expires_at = token_data['expires_at']
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if isinstance(expires_at, str):
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# SQLite returns timestamps as strings, parse them
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expires_at = datetime.fromisoformat(expires_at)
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if datetime.utcnow() > expires_at:
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logger.info(
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f"Token validation failed: expired "
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f"(me: {token_data['me']}, expired: {expires_at.isoformat()})"
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)
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return None
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# Check revocation
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if token_data['revoked']:
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logger.warning(
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f"Token validation failed: revoked "
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f"(me: {token_data['me']}, client: {token_data['client_id']})"
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)
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return None
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# Valid token - return metadata
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logger.debug(f"Token validated successfully (me: {token_data['me']})")
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return {
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'me': token_data['me'],
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'client_id': token_data['client_id'],
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'scope': token_data['scope']
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}
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except Exception as e:
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logger.error(f"Token validation error: {e}")
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return None
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def revoke_token(self, provided_token: str) -> bool:
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"""
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Revoke access token.
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Note: Not used in v1.0.0 (no revocation endpoint).
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Included for Phase 3 completeness and future use.
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Args:
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provided_token: Access token to revoke
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Returns:
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True if token revoked successfully
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False if token not found
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Raises:
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No exceptions raised
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"""
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try:
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# Hash token for lookup
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token_hash = hashlib.sha256(provided_token.encode('utf-8')).hexdigest()
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# Update revoked flag
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engine = self.database.get_engine()
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with engine.begin() as conn:
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result = conn.execute(
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text("""
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UPDATE tokens
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SET revoked = 1
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WHERE token_hash = :token_hash
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"""),
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{"token_hash": token_hash}
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)
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rows_affected = result.rowcount
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if rows_affected > 0:
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logger.info(f"Token revoked (prefix: {provided_token[:8]}...)")
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return True
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else:
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logger.warning(f"Token revocation failed: not found (prefix: {provided_token[:8]}...)")
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return False
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except Exception as e:
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logger.error(f"Token revocation error: {e}")
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return False
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def cleanup_expired_tokens(self) -> int:
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"""
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Delete expired tokens from database.
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Note: Can be called periodically (e.g., hourly) to prevent
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database growth. Not critical for v1.0.0 (small scale).
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Returns:
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Number of tokens deleted
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Raises:
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DatabaseError: If database operations fail
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"""
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current_time = datetime.utcnow()
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engine = self.database.get_engine()
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with engine.begin() as conn:
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result = conn.execute(
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text("""
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DELETE FROM tokens
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WHERE expires_at < :current_time
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"""),
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{"current_time": current_time}
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)
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deleted_count = result.rowcount
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if deleted_count > 0:
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logger.info(f"Cleaned up {deleted_count} expired tokens")
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else:
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logger.debug("No expired tokens to clean up")
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return deleted_count
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