pihole-ftl: fix build (#495363)

From 14311f18ae9427a0baa1e0cb67198580d9d2dc69 Mon Sep 17 00:00:00 2001

From: averyvigolo <avery@averyv.me>

Date: Sun, 24 Aug 2025 18:35:37 +0100

Subject: [PATCH] Only use redirect_root_handler if webhome is set (fixes

 #2518)

This fixes an infinite redirect on the home page when authentication is enabled.

The redirects are caused by XHR calls to the API, which receive a 401 response, and

the error handlers simply reload the page.

If webhome is not set, the default request handler should be used to properly

handle authentication. So, conditionally enable redirect_root_handler, if

webhome is not empty or `/`. This fixes the problem, as there's an immediate

redirect to /login, before any XHR calls.

Remove the initial fix in https://github.com/pi-hole/FTL/pull/2521, as it is no

longer necessary. That fix involved checking in redirect_root_handler, if the

redirect destination is the same as the request URI.

Signed-off-by: averyvigolo <avery@averyv.me>

---

 src/webserver/webserver.c | 15 ++++++++-------

 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/src/webserver/webserver.c b/src/webserver/webserver.c

index e0999d230..c3e32a35c 100644

--- a/src/webserver/webserver.c

+++ b/src/webserver/webserver.c

@@ -720,7 +714,14 @@ void http_init(void)

 	// prefix should be stripped away by the reverse proxy

 	mg_set_request_handler(ctx, "/api", api_handler, NULL);

-	mg_set_request_handler(ctx, "/$", redirect_root_handler, NULL);

+	if(strcmp(prefix_webhome, "/") == 0 || strlen(prefix_webhome) == 0)

+	{

+		log_debug(DEBUG_API, "Not redirecting root since webhome is '%s'",

+			  prefix_webhome);

+	} else {

+		// Redirect requests to / to the webhome path.

+		mg_set_request_handler(ctx, "/$", redirect_root_handler, NULL);

+	}

 	if(strcmp(config.webserver.paths.webhome.v.s, "/") == 0 &&

 	   config.dns.blocking.mode.v.blocking_mode == MODE_IP)

{

  lib,

  stdenv,

  nixosTests,

  fetchFromGitHub,

  cmake,

  fetchFromGitHub,

  gmp,

  lib,

  libidn2,

  libunistring,

  mbedtls,

  ncurses,

  nettle,

  nix-update-script,

  nixosTests,

  readline,

  stdenv,

  versionCheckHook,

  xxd,

  iproute2,

}:

stdenv.mkDerivation (finalAttrs: {

    hash = "sha256-OpbBd+HS/gwcWNe/6VB3glout1sifJ8o5EnKuXfyZ/o=";

  };

  patches = [

    # https://github.com/pi-hole/FTL/pull/2610: Fix authentication redirect when webhome is /

    ./disable-redirect-root.patch

  ];

  nativeBuildInputs = [

    cmake

    xxd

  postPatch = ''

    substituteInPlace src/version.c.in \

      --replace-quiet "@GIT_VERSION@" "v${finalAttrs.version}" \

      --replace-quiet "@GIT_DATE@" "1970-01-01" \

      --replace-quiet "@GIT_BRANCH@" "master" \

      --replace-quiet "@GIT_TAG@" "v${finalAttrs.version}" \

      --replace-quiet "@GIT_HASH@" "builtfromreleasetarball"

      --replace-fail "@GIT_VERSION@" "v${finalAttrs.version}" \

      --replace-fail "@GIT_DATE@" "1970-01-01" \

      --replace-fail "@GIT_BRANCH@" "master" \

      --replace-fail "@GIT_TAG@" "v${finalAttrs.version}" \

      --replace-fail "@GIT_HASH@" "builtfromreleasetarball"

    # Remove hard-coded absolute path to the pihole script, rely on it being provided by $PATH

    # Use execvp instead of execv so PATH is followed

    # Remove hard-coded absolute path to the pihole script, rely on it

    # being provided by $PATH.  Use execvp instead of execv so PATH is

    # followed.

    substituteInPlace src/api/action.c \

      --replace-fail "/usr/local/bin/pihole" "pihole" \

      --replace-fail "execv" "execvp"

    substituteInPlace src/database/network-table.c \

      --replace-fail "ip neigh show" "${lib.getExe' iproute2 "ip"} neigh show" \

      --replace-fail "ip address show" "${lib.getExe' iproute2 "ip"} address show"

  '';

  installPhase = ''

    runHook preInstall

    install -Dm 555 -t $out/bin pihole-FTL

    install -D pihole-FTL $out/bin/${finalAttrs.meta.mainProgram}

    runHook postInstall

  '';

  passthru = {

    settingsTemplate = ./pihole.toml;

    tests = nixosTests.pihole-ftl;

    updateScript = nix-update-script { };

  };

  doInstallCheck = true;

  nativeInstallCheckInputs = [ versionCheckHook ];

  meta = {

    description = "Pi-hole FTL engine";

    homepage = "https://github.com/pi-hole/FTL";