65 lines
1.7 KiB
Go
65 lines
1.7 KiB
Go
package denyrouterrecursion
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import (
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"errors"
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"hash/fnv"
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"net/http"
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"strconv"
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"github.com/containous/alice"
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"github.com/rs/zerolog/log"
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"github.com/traefik/traefik/v3/pkg/logs"
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)
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const xTraefikRouter = "X-Traefik-Router"
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type DenyRouterRecursion struct {
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routerName string
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routerNameHash string
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next http.Handler
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}
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// WrapHandler Wraps router to alice.Constructor.
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func WrapHandler(routerName string) alice.Constructor {
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return func(next http.Handler) (http.Handler, error) {
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return New(routerName, next)
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}
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}
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// New creates a new DenyRouterRecursion.
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// DenyRouterRecursion middleware is an internal middleware used to avoid infinite requests loop on the same router.
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func New(routerName string, next http.Handler) (*DenyRouterRecursion, error) {
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if routerName == "" {
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return nil, errors.New("routerName cannot be empty")
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}
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return &DenyRouterRecursion{
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routerName: routerName,
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routerNameHash: makeHash(routerName),
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next: next,
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}, nil
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}
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// ServeHTTP implements http.Handler.
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func (l *DenyRouterRecursion) ServeHTTP(rw http.ResponseWriter, req *http.Request) {
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if req.Header.Get(xTraefikRouter) == l.routerNameHash {
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logger := log.With().Str(logs.MiddlewareType, "DenyRouterRecursion").Logger()
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logger.Debug().Msgf("Rejecting request in provenance of the same router (%q) to stop potential infinite loop.", l.routerName)
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rw.WriteHeader(http.StatusBadRequest)
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return
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}
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req.Header.Set(xTraefikRouter, l.routerNameHash)
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l.next.ServeHTTP(rw, req)
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}
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func makeHash(routerName string) string {
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hasher := fnv.New64()
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// purposely ignoring the error, as no error can be returned from the implementation.
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_, _ = hasher.Write([]byte(routerName))
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return strconv.FormatUint(hasher.Sum64(), 16)
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}
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