emissary/internal/server/authorization.go

package server

import (
	"context"
	"fmt"
	"net/http"

	"forge.cadoles.com/Cadoles/emissary/internal/auth"
	"forge.cadoles.com/Cadoles/emissary/internal/auth/agent"
	"forge.cadoles.com/Cadoles/emissary/internal/auth/thirdparty"
	"github.com/getsentry/sentry-go"
	"github.com/pkg/errors"
	"gitlab.com/wpetit/goweb/api"
	"gitlab.com/wpetit/goweb/logger"
)

var ErrCodeForbidden api.ErrorCode = "forbidden"

func assertGlobalReadAccess(h http.Handler) http.Handler {
	fn := func(w http.ResponseWriter, r *http.Request) {
		reqUser, ok := assertRequestUser(w, r)
		if !ok {
			return
		}

		switch user := reqUser.(type) {
		case *thirdparty.User:
			role := user.Role()
			if role == thirdparty.RoleReader || role == thirdparty.RoleWriter {
				h.ServeHTTP(w, r)

				return
			}

		case *agent.User:
			// Agents dont have global read access

		default:
			logUnexpectedUserType(r.Context(), reqUser)
		}

		forbidden(w, r)
	}

	return http.HandlerFunc(fn)
}

func assertAgentWriteAccess(h http.Handler) http.Handler {
	fn := func(w http.ResponseWriter, r *http.Request) {
		reqUser, ok := assertRequestUser(w, r)
		if !ok {
			return
		}

		agentID, ok := getAgentID(w, r)
		if !ok {
			return
		}

		switch user := reqUser.(type) {
		case *thirdparty.User:
			role := user.Role()
			if role == thirdparty.RoleWriter {
				h.ServeHTTP(w, r)

				return
			}

		case *agent.User:
			if user.Agent().ID == agentID {
				h.ServeHTTP(w, r)

				return
			}

		default:
			logUnexpectedUserType(r.Context(), reqUser)
		}

		forbidden(w, r)
	}

	return http.HandlerFunc(fn)
}

func assertAgentReadAccess(h http.Handler) http.Handler {
	fn := func(w http.ResponseWriter, r *http.Request) {
		reqUser, ok := assertRequestUser(w, r)
		if !ok {
			return
		}

		agentID, ok := getAgentID(w, r)
		if !ok {
			return
		}

		switch user := reqUser.(type) {
		case *thirdparty.User:
			role := user.Role()
			if role == thirdparty.RoleReader || role == thirdparty.RoleWriter {
				h.ServeHTTP(w, r)

				return
			}

		case *agent.User:
			if user.Agent().ID == agentID {
				h.ServeHTTP(w, r)

				return
			}

		default:
			logUnexpectedUserType(r.Context(), reqUser)
		}

		forbidden(w, r)
	}

	return http.HandlerFunc(fn)
}

func assertRequestUser(w http.ResponseWriter, r *http.Request) (auth.User, bool) {
	ctx := r.Context()
	user, err := auth.CtxUser(ctx)
	if err != nil {
		err = errors.WithStack(err)
		logger.Error(ctx, "could not retrieve user", logger.E(err))
		sentry.CaptureException(err)

		forbidden(w, r)

		return nil, false
	}

	if user == nil {
		forbidden(w, r)

		return nil, false
	}

	return user, true
}

func forbidden(w http.ResponseWriter, r *http.Request) {
	logger.Warn(r.Context(), "forbidden", logger.F("path", r.URL.Path))

	api.ErrorResponse(w, http.StatusForbidden, ErrCodeForbidden, nil)
}

func logUnexpectedUserType(ctx context.Context, user auth.User) {
	logger.Warn(
		ctx, "unexpected user type",
		logger.F("subject", user.Subject()),
		logger.F("type", fmt.Sprintf("%T", user)),
	)
}