Remove REDIRECT_BROKEN_DNS page and instead use "Failed Dependency" error

README.md

@@ -5,7 +5,6 @@
 - `RAW_DOMAIN` (default: `raw.codeberg.org`): domain for raw resources.
 - `GITEA_ROOT` (default: `https://codeberg.org`): root of the upstream Gitea instance.
 - `GITEA_API_TOKEN` (default: empty): API token for the Gitea instance to access non-public (e.g. limited) repos.
-- `REDIRECT_BROKEN_DNS` (default: https://docs.codeberg.org/pages/custom-domains/): info page for setting up DNS, shown for invalid DNS setups.
 - `REDIRECT_RAW_INFO` (default: https://docs.codeberg.org/pages/raw-content/): info page for raw resources, shown if no resource is provided.
 - `ACME_API` (default: https://acme-v02.api.letsencrypt.org/directory): set this to https://acme.mock.director to use invalid certificates without any verification (great for debugging).  
   ZeroSSL might be better in the future as it doesn't have rate limits and doesn't clash with the official Codeberg certificates (which are using Let's Encrypt), but I couldn't get it to work yet.

handler.go

@@ -242,7 +242,7 @@ func handler(ctx *fasthttp.RequestCtx) {
 		// Serve pages from external domains
 		targetOwner, targetRepo, targetBranch = getTargetFromDNS(trimmedHostStr)
 		if targetOwner == "" {
-			ctx.Redirect(BrokenDNSPage, fasthttp.StatusTemporaryRedirect)
+			returnErrorPage(ctx, fasthttp.StatusFailedDependency)
 			return
 		}
 
@@ -268,7 +268,7 @@ func handler(ctx *fasthttp.RequestCtx) {
 					ctx.Redirect("https://"+canonicalDomain+string(ctx.RequestURI()), fasthttp.StatusTemporaryRedirect)
 					return
 				} else {
-					ctx.Redirect(BrokenDNSPage, fasthttp.StatusTemporaryRedirect)
+					returnErrorPage(ctx, fasthttp.StatusFailedDependency)
 					return
 				}
 			}

main.go

@@ -44,9 +44,6 @@ var GiteaApiToken = envOr("GITEA_API_TOKEN", "")
 //go:embed 404.html
 var NotFoundPage []byte
 
-// BrokenDNSPage will be shown (with a redirect) when trying to access a domain for which no DNS CNAME record exists.
-var BrokenDNSPage = envOr("REDIRECT_BROKEN_DNS", "https://docs.codeberg.org/pages/custom-domains/")
-
 // RawDomain specifies the domain from which raw repository content shall be served in the following format:
 // https://{RawDomain}/{owner}/{repo}[/{branch|tag|commit}/{version}]/{filepath...}
 // (set to []byte(nil) to disable raw content hosting)