fix(domain): validate hostname format to reject invalid characters (#4729)

* fix(domain): validate hostname format to reject invalid characters

Underscores and other invalid characters were accepted in domain
inputs with no validation, causing Let's Encrypt to silently fail
certificate issuance while Dokploy fell back to a self-signed cert.

Fixes #4716

* fix(create-server): update SSH key label for clarity in server creation form

apps/dokploy/__test__/utils/hostname-validation.test.ts

@@ -0,0 +1,46 @@
+import { VALID_HOSTNAME_REGEX } from "@dokploy/server";
+import { describe, expect, it } from "vitest";
+
+describe("VALID_HOSTNAME_REGEX", () => {
+	it.each([
+		"example.com",
+		"sub.example.com",
+		"bbn-client.example.com",
+		"a.b.c.example.co",
+		"xn--80ak6aa92e.com",
+		"123.example.com",
+	])("accepts valid hostname %s", (host) => {
+		expect(VALID_HOSTNAME_REGEX.test(host)).toBe(true);
+	});
+
+	it.each([
+		"bbn_client.example.com",
+		"-example.com",
+		"example-.com",
+		"example",
+		"exa mple.com",
+		"example..com",
+		"",
+		`a${"a".repeat(63)}.com`,
+	])("rejects invalid hostname %s", (host) => {
+		expect(VALID_HOSTNAME_REGEX.test(host)).toBe(false);
+	});
+
+	// IDNs (Cyrillic, German umlauts, etc.) must be submitted in their
+	// ACME/punycode form ("xn--...") — that's what Let's Encrypt issues
+	// certificates for, so raw Unicode labels are rejected here.
+	it.each(["пример.рф", "bücher.de", "日本語.jp"])(
+		"rejects raw unicode IDN %s",
+		(host) => {
+			expect(VALID_HOSTNAME_REGEX.test(host)).toBe(false);
+		},
+	);
+
+	it.each([
+		"xn--e1afmkfd.xn--p1ai", // punycode for пример.рф
+		"xn--bcher-kva.de", // punycode for bücher.de
+		"xn--wgv71a119e.jp", // punycode for 日本語.jp
+	])("accepts punycode-encoded IDN %s", (host) => {
+		expect(VALID_HOSTNAME_REGEX.test(host)).toBe(true);
+	});
+});

apps/dokploy/components/dashboard/application/domains/handle-domain.tsx

@@ -1,3 +1,7 @@
+import {
+	INVALID_HOSTNAME_MESSAGE,
+	VALID_HOSTNAME_REGEX,
+} from "@dokploy/server/utils/hostname-validation";
 import { standardSchemaResolver as zodResolver } from "@hookform/resolvers/standard-schema";
 import { DatabaseZap, Dices, RefreshCw, X } from "lucide-react";
 import Link from "next/link";
@@ -53,7 +57,10 @@ export const domain = z
 			.refine((val) => val === val.trim(), {
 				message: "Domain name cannot have leading or trailing spaces",
 			})
-			.transform((val) => val.trim()),
+			.transform((val) => val.trim())
+			.refine((val) => VALID_HOSTNAME_REGEX.test(val), {
+				message: INVALID_HOSTNAME_MESSAGE,
+			}),
 		path: z.string().min(1).optional(),
 		internalPath: z.string().optional(),
 		stripPath: z.boolean().optional(),

apps/dokploy/components/dashboard/settings/servers/welcome-stripe/create-server.tsx

@@ -195,9 +195,7 @@ export const CreateServer = ({ stepper }: Props) => {
 														{sshKey.name}
 													</SelectItem>
 												))}
-												<SelectLabel>
-													Registries ({sshKeys?.length})
-												</SelectLabel>
+												<SelectLabel>SSH Keys ({sshKeys?.length})</SelectLabel>
 											</SelectGroup>
 										</SelectContent>
 									</Select>

apps/dokploy/components/dashboard/settings/web-domain.tsx

@@ -1,3 +1,7 @@
+import {
+	INVALID_HOSTNAME_MESSAGE,
+	VALID_HOSTNAME_REGEX,
+} from "@dokploy/server/utils/hostname-validation";
 import { standardSchemaResolver as zodResolver } from "@hookform/resolvers/standard-schema";
 import { GlobeIcon } from "lucide-react";
 import { useEffect } from "react";
@@ -35,7 +39,13 @@ import { api } from "@/utils/api";
 
 const addServerDomain = z
 	.object({
-		domain: z.string().trim().toLowerCase(),
+		domain: z
+			.string()
+			.trim()
+			.toLowerCase()
+			.refine((val) => VALID_HOSTNAME_REGEX.test(val), {
+				message: INVALID_HOSTNAME_MESSAGE,
+			}),
 		letsEncryptEmail: z.string(),
 		https: z.boolean().optional(),
 		certificateType: z.enum(["letsencrypt", "none", "custom"]),

apps/dokploy/server/db/validations/domain.ts

@@ -1,3 +1,7 @@
+import {
+	INVALID_HOSTNAME_MESSAGE,
+	VALID_HOSTNAME_REGEX,
+} from "@dokploy/server/utils/hostname-validation";
 import { z } from "zod";
 
 export const domain = z
@@ -8,7 +12,10 @@ export const domain = z
 			.refine((val) => val === val.trim(), {
 				message: "Domain name cannot have leading or trailing spaces",
 			})
-			.transform((val) => val.trim()),
+			.transform((val) => val.trim())
+			.refine((val) => VALID_HOSTNAME_REGEX.test(val), {
+				message: INVALID_HOSTNAME_MESSAGE,
+			}),
 		path: z.string().min(1).optional(),
 		port: z
 			.number()
@@ -45,7 +52,10 @@ export const domainCompose = z
 			.refine((val) => val === val.trim(), {
 				message: "Domain name cannot have leading or trailing spaces",
 			})
-			.transform((val) => val.trim()),
+			.transform((val) => val.trim())
+			.refine((val) => VALID_HOSTNAME_REGEX.test(val), {
+				message: INVALID_HOSTNAME_MESSAGE,
+			}),
 		path: z.string().min(1).optional(),
 		port: z
 			.number()

packages/server/src/db/validations/domain.ts

@@ -1,4 +1,8 @@
 import { z } from "zod";
+import {
+	INVALID_HOSTNAME_MESSAGE,
+	VALID_HOSTNAME_REGEX,
+} from "../../utils/hostname-validation";
 
 export const domain = z
 	.object({
@@ -8,7 +12,10 @@ export const domain = z
 			.refine((val) => val === val.trim(), {
 				message: "Domain name cannot have leading or trailing spaces",
 			})
-			.transform((val) => val.trim()),
+			.transform((val) => val.trim())
+			.refine((val) => VALID_HOSTNAME_REGEX.test(val), {
+				message: INVALID_HOSTNAME_MESSAGE,
+			}),
 		path: z.string().min(1).optional(),
 		internalPath: z.string().optional(),
 		stripPath: z.boolean().optional(),
@@ -71,7 +78,10 @@ export const domainCompose = z
 			.refine((val) => val === val.trim(), {
 				message: "Domain name cannot have leading or trailing spaces",
 			})
-			.transform((val) => val.trim()),
+			.transform((val) => val.trim())
+			.refine((val) => VALID_HOSTNAME_REGEX.test(val), {
+				message: INVALID_HOSTNAME_MESSAGE,
+			}),
 		path: z.string().min(1).optional(),
 		internalPath: z.string().optional(),
 		stripPath: z.boolean().optional(),

packages/server/src/index.ts

@@ -104,6 +104,7 @@ export * from "./utils/filesystem/directory";
 export * from "./utils/filesystem/ssh";
 export * from "./utils/git-branch-validation";
 export * from "./utils/gpu-setup";
+export * from "./utils/hostname-validation";
 export * from "./utils/notifications/build-error";
 export * from "./utils/notifications/build-success";
 export * from "./utils/notifications/database-backup";

packages/server/src/utils/hostname-validation.ts

@@ -0,0 +1,8 @@
+// Valid hostname per RFC 1123: labels of letters, digits and hyphens
+// (no leading/trailing hyphen), separated by dots. Underscores are rejected
+// because Let's Encrypt refuses to issue certificates for them.
+export const VALID_HOSTNAME_REGEX =
+	/^(?:[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?\.)+[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?$/;
+
+export const INVALID_HOSTNAME_MESSAGE =
+	"Invalid domain name. Use only letters, numbers, hyphens and dots (e.g. example.com). Underscores are not allowed.";