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Add error handling for nil RouteContext in URLFormat #841

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Add error handling for nil RouteContext in URLFormat #841

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11 changes: 10 additions & 1 deletion middleware/url_format.go
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Original file line number Diff line number Diff line change
Expand Up @@ -8,6 +8,10 @@ import (
"github.com/go-chi/chi/v5"
)

const (
errRouteContextNil = "RouteContext was nil."
)

var (
// URLFormatCtxKey is the context.Context key to store the URL format data
// for a request.
Expand Down Expand Up @@ -52,7 +56,12 @@ func URLFormat(next http.Handler) http.Handler {
path := r.URL.Path

rctx := chi.RouteContext(r.Context())
if rctx != nil && rctx.RoutePath != "" {
if rctx == nil {
http.Error(w, errRouteContextNil, http.StatusInternalServerError)
return
}

if rctx.RoutePath != "" {
path = rctx.RoutePath
}

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29 changes: 29 additions & 0 deletions middleware/url_format_test.go
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Original file line number Diff line number Diff line change
@@ -1,8 +1,10 @@
package middleware

import (
"context"
"net/http"
"net/http/httptest"
"strings"
"testing"

"github.com/go-chi/chi/v5"
Expand Down Expand Up @@ -67,3 +69,30 @@ func TestURLFormatInSubRouter(t *testing.T) {
t.Fatalf(resp)
}
}

func TestURLFormatWithoutChiRouteContext(t *testing.T) {
r := chi.NewRouter()

r.Use(func(next http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
newCtx := context.WithValue(r.Context(), chi.RouteCtxKey, nil)
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@VojtechVitek VojtechVitek Sep 18, 2024 •
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Hi @Taaipi,

Thanks for the PR!

It looks like this test cases injects a nil RouteContext down the chain intentionally.

Do you have an example how could this happen in real-world use case? I wonder how is the middleware.URLFormat ever called without chi route context unless we set it to nil explicitly.

Thanks!

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I guess based on #718, it'd be better to create a test case with some sub-routers (instead of setting nil). Right?

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Are you using middleware.URLFormat outside of chi router?

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@VojtechVitek
Thank you for the review.

Are you using middleware.URLFormat outside of chi router?

Yes, this issue could arise if middleware.URLFormat is used outside of the chi router or if RouteContext is explicitly set to nil (though I haven’t fully grasped the intent behind such a scenario based on issue #839). However, since encountering such a problem is conceivable, even though it remains an edge case, I’ve added error handling to catch and address it early.

For now, I will omit the case where nil is intentionally assigned. Instead, I’m considering adding a test case for error handling when the router is not used. What do you think?

next.ServeHTTP(w, r.WithContext(newCtx))
})
})
r.Use(URLFormat)
r.Get("/", func(w http.ResponseWriter, r *http.Request) {
w.Write([]byte("OK"))
})

ts := httptest.NewServer(r)
defer ts.Close()

resp, respBody := testRequest(t, ts, "GET", "/", nil)
if resp.StatusCode != http.StatusInternalServerError {
t.Fatalf("non 500 response: %v", resp.StatusCode)
}

if strings.TrimSpace(respBody) != errRouteContextNil {
t.Fatalf("Expected error message: %s, but got: %s", errRouteContextNil, respBody)
}
}