# Silo Auth Middleware

## Middleware Chain

Every request passes through this middleware stack in order:

```
RequestID          Assigns X-Request-ID header
    |
RealIP             Extracts client IP from X-Forwarded-For
    |
RequestLogger      Logs method, path, status, duration (zerolog)
    |
Recoverer          Catches panics, logs stack trace, returns 500
    |
CORS               Validates origin, sets Access-Control headers
    |
SessionLoadAndSave Loads session from PostgreSQL, saves on response
    |
[route group middleware applied per-group below]
```

## Route Groups

### Public (no auth)

```
GET  /health
GET  /ready
GET  /login
POST /login
POST /logout
GET  /auth/oidc
GET  /auth/callback
```

No authentication or CSRF middleware. The login form includes a CSRF hidden field but nosurf is not enforced on these routes (they are outside the CSRF-protected group).

### Web UI (auth + CSRF)

```
RequireAuth -> CSRFProtect -> Handler

GET  /                       Items page
GET  /projects               Projects page
GET  /schemas                Schemas page
GET  /settings               Settings page (account info, tokens)
POST /settings/tokens        Create API token (form)
POST /settings/tokens/{id}/revoke   Revoke token (form)
```

Both `RequireAuth` and `CSRFProtect` are applied. Form submissions must include a `csrf_token` hidden field with the value from `nosurf.Token(r)`.

### API (auth, no CSRF)

```
RequireAuth -> [RequireRole where needed] -> Handler

GET    /api/auth/me                  Current user info (viewer)
GET    /api/auth/tokens              List tokens (viewer)
POST   /api/auth/tokens              Create token (viewer)
DELETE /api/auth/tokens/{id}         Revoke token (viewer)

GET    /api/schemas/*                Read schemas (viewer)
POST   /api/schemas/*/segments/*     Modify schema values (editor)

GET    /api/projects/*               Read projects (viewer)
POST   /api/projects                 Create project (editor)
PUT    /api/projects/{code}          Update project (editor)
DELETE /api/projects/{code}          Delete project (editor)

GET    /api/items/*                  Read items (viewer)
POST   /api/items                    Create item (editor)
PUT    /api/items/{partNumber}       Update item (editor)
DELETE /api/items/{partNumber}       Delete item (editor)
POST   /api/items/{partNumber}/file  Upload file (editor)
POST   /api/items/import             CSV import (editor)

GET    /api/items/{partNumber}/bom/* Read BOM (viewer)
POST   /api/items/{partNumber}/bom   Add BOM entry (editor)
PUT    /api/items/{partNumber}/bom/* Update BOM entry (editor)
DELETE /api/items/{partNumber}/bom/* Delete BOM entry (editor)

POST   /api/generate-part-number     Generate PN (editor)

GET    /api/integrations/odoo/*      Read Odoo config (viewer)
PUT    /api/integrations/odoo/*      Modify Odoo config (editor)
POST   /api/integrations/odoo/*      Odoo sync operations (editor)
```

API routes are exempt from CSRF (they use Bearer token auth). CORS credentials are allowed so browser-based API clients with session cookies work.

## RequireAuth

`internal/api/middleware.go`

Authentication check order:

1. **Auth disabled?** Inject synthetic dev user (`admin` role) and continue
2. **Bearer token?** Extract from `Authorization: Bearer silo_...` header, validate via `auth.Service.ValidateToken()`. On success, inject user into context
3. **Session cookie?** Read `user_id` from `scs` session, look up user via `auth.Service.GetUserByID()`. On success, inject user into context. On stale session (user not found), destroy session
4. **None of the above?**
   - API requests (`/api/*`): Return `401 Unauthorized` JSON
   - Web requests: Redirect to `/login?next=<current-path>`

## RequireRole

`internal/api/middleware.go`

Applied as per-group middleware on routes that require a minimum role:

```go
r.Use(server.RequireRole(auth.RoleEditor))
```

Checks `auth.RoleSatisfies(user.Role, minimum)` against the hierarchy `admin > editor > viewer`. Returns:

- `401 Unauthorized` if no user in context (should not happen after RequireAuth)
- `403 Forbidden` with message `"Insufficient permissions: requires <role> role"` if role is too low

## CSRFProtect

`internal/api/middleware.go`

Wraps the `justinas/nosurf` library:

- Cookie: `csrf_token`, HttpOnly, SameSite=Lax, Secure when auth enabled
- Exempt paths: `/api/*`, `/health`, `/ready`
- Form field name: `csrf_token`
- Failure: Returns `403 Forbidden` with `"CSRF token validation failed"`

Templates inject the token via `{{.CSRFToken}}` which is populated from `nosurf.Token(r)`.

## CORS Configuration

Configured in `internal/api/routes.go`:

| Setting | Auth Disabled | Auth Enabled |
|---------|---------------|--------------|
| Allowed Origins | `*` | From `auth.cors.allowed_origins` config |
| Allow Credentials | `false` | `true` (needed for session cookies) |
| Allowed Methods | GET, POST, PUT, PATCH, DELETE, OPTIONS | Same |
| Allowed Headers | Accept, Authorization, Content-Type, X-CSRF-Token, X-Request-ID | Same |
| Max Age | 300 seconds | 300 seconds |

FreeCAD uses direct HTTP (not browser), so CORS does not affect it. Browser-based tools on other origins need their origin in the allowed list.

## Request Flow Examples

### Browser Login

```
GET /projects
  -> RequestLogger
  -> CORS (pass)
  -> Session (loads empty session)
  -> RequireAuth: no token, no session user_id
  -> Redirect 303 /login?next=/projects

POST /login (username=alice, password=...)
  -> RequestLogger
  -> CORS (pass)
  -> Session (loads)
  -> HandleLogin: auth.Authenticate(ctx, "alice", password)
  -> Session: put user_id, renew token
  -> Redirect 303 /projects

GET /projects
  -> Session (loads, has user_id)
  -> RequireAuth: session -> GetUserByID -> inject alice
  -> CSRFProtect: GET request, passes
  -> HandleProjectsPage: renders with alice's info
```

### API Token Request

```
GET /api/items
  Authorization: Bearer silo_a1b2c3d4...

  -> RequireAuth: Bearer token found
  -> ValidateToken: SHA-256 hash lookup, check expiry, check user active
  -> Inject user into context
  -> HandleListItems: returns JSON
```