Commilitia-Drop/internal/httpapi/selftoken.go

package httpapi

import (
	"time"

	"github.com/go-jose/go-jose/v4"
	"github.com/go-jose/go-jose/v4/jwt"
)

// mintSessionToken signs a short-lived cdrop self-signed session access token
// (AUTH.md §3.1): HS256 over the SessionSecret-derived key, sub=userID, sid=the
// web_sessions row id, typ=session, scope=full|guest. The matching verifier is
// jwtauth.verifySelfToken. Returns the token and its lifetime in seconds (for the
// client's expires_in). Used by scan-login and self/guest session refresh — never
// touches the IdP.
func (s *Server) mintSessionToken(userID, sid, scope string) (string, int, error) {
	ttl := time.Duration(s.cfg.SessionTokenTTLSeconds) * time.Second
	now := time.Now()
	sig, err := jose.NewSigner(
		jose.SigningKey{Algorithm: jose.HS256, Key: s.sessionTokenKey},
		(&jose.SignerOptions{}).WithType("JWT"),
	)
	if err != nil {
		return "", 0, err
	}
	std := jwt.Claims{
		Subject:  userID,
		IssuedAt: jwt.NewNumericDate(now),
		Expiry:   jwt.NewNumericDate(now.Add(ttl)),
	}
	tok, err := jwt.Signed(sig).
		Claims(std).
		Claims(map[string]any{"typ": "session", "scope": scope, "sid": sid}).
		Serialize()
	if err != nil {
		return "", 0, err
	}
	return tok, int(ttl / time.Second), nil
}