Files
minstrel/internal/auth/middleware.go
T
bvandeusen d86af7397d
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feat(auth): active sessions API with origin/current IP — #370
Server half of the active-sessions surface. Web UI follows.

The operator wants this specifically to notice a compromised account, which
sets the bar: the addresses have to be trustworthy, or the feature is worse
than absent because it looks like evidence.

Migration 0052 adds created_ip + last_ip. Two columns, not one, and the pair
is the signal: a session issued at home and now being used from elsewhere is
the shape of a stolen token, and neither column alone can show that. Typed
text, matching the user_agent column beside it — these are displayed, never
queried by subnet, and inet round-trips through pgx as a netip.Prefix that
renders "1.2.3.4/32".

The rest of the schema was already waiting. Migration 0004 anticipated this
exactly: "last_seen_at enables an 'active sessions' UI later (not wired in
this plan) without schema churn." last_seen_at is live data — the auth
middleware already touches it per request — so last_ip rides that same
UPDATE for free.

Getting the address right is the substance here. Nothing extracted a client
IP anywhere before, and both obvious approaches are wrong:

- RemoteAddr alone shows the reverse proxy on every session, which is the
  normal self-hosted deployment. Noise shaped like data.
- Trusting X-Forwarded-For lets any client choose what its victim sees. A
  security surface an attacker can write to is worse than none.

So auth.ClientIP trusts the header only when the request actually arrived
from a proxy range. Public RemoteAddr means a direct connection, so XFF is
attacker-controlled and ignored outright. Private RemoteAddr means we walk
XFF right-to-left — proxies append, so the right end is what our own
infrastructure wrote — and take the first non-proxy address. A forged XFF
only prepends to the left end, which that walk never reaches. Unit-tested,
including both spoofing shapes.

Fails closed on a public-addressed proxy (separate host, CDN): we report the
proxy rather than trusting a forgeable header. Documented at the function.

Endpoints, all scoped by user_id per rule #47:

  GET    /api/me/sessions                → list, flagging the current row
  DELETE /api/me/sessions/{id}           → 204, or 404 if not yours
  POST   /api/me/sessions/logout-others  → {"revoked": n}

Keyed on session id alone, any household member could revoke another's
session by guessing a uuid, so the delete carries user_id in its WHERE and
:execrows distinguishes "not yours" (404) from a false 204. There's a test
that asserts the row actually survives, not merely that we returned 404.

The middleware now also puts the session id in context. logout-others is
defined by exclusion, and without knowing which session is ours the
safe-looking action deletes everything including the caller's — so it
refuses rather than guesses when the id is absent, and that refusal is
tested for non-deletion too.

audit_log.action is plain text with no CHECK, so the two new actions need no
migration (rule #36 checked, not assumed).

Codegen is real sqlc 1.31.1 via the container in `make generate` — docker is
present on this workstation even though Go and sqlc aren't — rather than the
hand-written .sql.go shortcut used in milestone #268.
2026-08-05 09:17:40 -04:00

35 lines
1.0 KiB
Go

package auth
import (
"context"
"github.com/jackc/pgx/v5/pgtype"
"git.fabledsword.com/bvandeusen/minstrel/internal/db/dbq"
)
type ctxKey int
const (
userCtxKey ctxKey = 1
sessionIDCtxKey ctxKey = 2
)
// UserFromContext returns the authenticated user placed in context by
// RequireUser. Returns false when RequireUser has not run (e.g. in tests that
// bypass the middleware, or programmer-error routing).
func UserFromContext(ctx context.Context) (dbq.User, bool) {
u, ok := ctx.Value(userCtxKey).(dbq.User)
return u, ok
}
// SessionIDFromContext returns the id of the session that authenticated this
// request. The active-sessions surface needs it for the two things it can't
// do from the user alone: mark which row is "this device", and exclude that
// row from "log out everywhere else" so the action doesn't sign the caller
// out of the page they invoked it from.
func SessionIDFromContext(ctx context.Context) (pgtype.UUID, bool) {
id, ok := ctx.Value(sessionIDCtxKey).(pgtype.UUID)
return id, ok
}