go-usertoken/caller.go

package usertoken

import (
	"context"
	"errors"
)

// ErrUnauthorized is wrapped by every failed token check.
// Startup and configuration failures do not wrap it.
var ErrUnauthorized = errors.New("unauthorized")

// Caller is the user a verified token names.
// Groups is nil when the token omitted the claim, and non-nil (possibly empty)
// when the claim was present.
type Caller struct {
	Subject  string
	Username string
	Groups   []string
}

type ctxKey int

const (
	ctxCaller ctxKey = iota
	ctxBearer
)

// CallerFromContext returns the user [Auth.Middleware] stored.
func CallerFromContext(ctx context.Context) (Caller, bool) {
	c, ok := ctx.Value(ctxCaller).(Caller)
	return c, ok
}

// BearerFromContext returns the raw JWT [Auth.Middleware] stored, without the
// "Bearer " prefix. Outbound calls send "Bearer " plus this string.
func BearerFromContext(ctx context.Context) (string, bool) {
	s, ok := ctx.Value(ctxBearer).(string)
	return s, ok
}

func withAuth(ctx context.Context, c Caller, raw string) context.Context {
	ctx = context.WithValue(ctx, ctxCaller, c)
	return context.WithValue(ctx, ctxBearer, raw)
}

func unauthorized(msg string) error {
	return errors.Join(errors.New(msg), ErrUnauthorized)
}