emissary/internal/auth/thirdparty/authenticator.go

package thirdparty

import (
	"context"
	"net/http"
	"strings"
	"time"

	"forge.cadoles.com/Cadoles/emissary/internal/auth"
	"forge.cadoles.com/Cadoles/emissary/internal/jwk"
	"github.com/pkg/errors"
	"gitlab.com/wpetit/goweb/logger"
)

const DefaultAcceptableSkew = 5 * time.Minute

type Authenticator struct {
	keys           jwk.Set
	issuer         string
	acceptableSkew time.Duration
}

// Authenticate implements auth.Authenticator.
func (a *Authenticator) Authenticate(ctx context.Context, r *http.Request) (auth.User, error) {
	ctx = logger.With(r.Context(), logger.F("remoteAddr", r.RemoteAddr))

	authorization := r.Header.Get("Authorization")
	if authorization == "" {
		return nil, errors.WithStack(auth.ErrUnauthenticated)
	}

	rawToken := strings.TrimPrefix(authorization, "Bearer ")
	if rawToken == "" {
		return nil, errors.WithStack(auth.ErrUnauthenticated)
	}

	token, err := parseToken(ctx, a.keys, a.issuer, rawToken, a.acceptableSkew)
	if err != nil {
		return nil, errors.WithStack(err)
	}

	rawRole, exists := token.Get(keyRole)
	if !exists {
		return nil, errors.New("could not find 'thumbprint' claim")
	}

	role, ok := rawRole.(string)
	if !ok {
		return nil, errors.Errorf("unexpected '%s' claim value: '%v'", keyRole, rawRole)
	}

	if !isValidRole(role) {
		return nil, errors.Errorf("invalid role '%s'", role)
	}

	user := &User{
		subject: token.Subject(),
		role:    Role(role),
	}

	return user, nil
}

func NewAuthenticator(keys jwk.Set, issuer string, acceptableSkew time.Duration) *Authenticator {
	return &Authenticator{
		keys:           keys,
		issuer:         issuer,
		acceptableSkew: acceptableSkew,
	}
}

var _ auth.Authenticator = &Authenticator{}