62 lines
1.6 KiB
Go
62 lines
1.6 KiB
Go
|
package denyrouterrecursion
|
||
|
|
|
||
|
|
import (
|
||
|
|
"errors"
|
||
|
|
"hash/fnv"
|
||
|
|
"net/http"
|
||
|
|
"strconv"
|
||
|
|
|
||
|
|
"github.com/containous/alice"
|
||
|
|
"github.com/traefik/traefik/v2/pkg/log"
|
||
|
|
)
|
||
|
|
|
||
|
|
const xTraefikRouter = "X-Traefik-Router"
|
||
|
|
|
||
|
|
type DenyRouterRecursion struct {
|
||
|
|
routerName string
|
||
|
|
routerNameHash string
|
||
|
|
next http.Handler
|
||
|
|
}
|
||
|
|
|
||
|
|
// WrapHandler Wraps router to alice.Constructor.
|
||
|
|
func WrapHandler(routerName string) alice.Constructor {
|
||
|
|
return func(next http.Handler) (http.Handler, error) {
|
||
|
|
return New(routerName, next)
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
// New creates a new DenyRouterRecursion.
|
||
|
|
// DenyRouterRecursion middleware is an internal middleware used to avoid infinite requests loop on the same router.
|
||
|
|
func New(routerName string, next http.Handler) (*DenyRouterRecursion, error) {
|
||
|
|
if routerName == "" {
|
||
|
|
return nil, errors.New("routerName cannot be empty")
|
||
|
|
}
|
||
|
|
|
||
|
|
return &DenyRouterRecursion{
|
||
|
|
routerName: routerName,
|
||
|
|
routerNameHash: makeHash(routerName),
|
||
|
|
next: next,
|
||
|
|
}, nil
|
||
|
|
}
|
||
|
|
|
||
|
|
// ServeHTTP implements http.Handler.
|
||
|
|
func (l *DenyRouterRecursion) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
|
||
|
|
if req.Header.Get(xTraefikRouter) == l.routerNameHash {
|
||
|
|
log.WithoutContext().Debugf("Rejecting request in provenance of the same router (%q) to stop potential infinite loop.", l.routerName)
|
||
|
|
rw.WriteHeader(http.StatusBadRequest)
|
||
|
|
|
||
|
|
return
|
||
|
|
}
|
||
|
|
|
||
|
|
req.Header.Set(xTraefikRouter, l.routerNameHash)
|
||
|
|
|
||
|
|
l.next.ServeHTTP(rw, req)
|
||
|
|
}
|
||
|
|
|
||
|
|
func makeHash(routerName string) string {
|
||
|
|
hasher := fnv.New64()
|
||
|
|
// purposely ignoring the error, as no error can be returned from the implementation.
|
||
|
|
_, _ = hasher.Write([]byte(routerName))
|
||
|
|
return strconv.FormatUint(hasher.Sum64(), 16)
|
||
|
|
}
|