Fix #3374

src/app/[orgId]/settings/resources/public/[niceId]/http/page.tsx

@@ -41,7 +41,7 @@ import {
 import { AxiosResponse } from "axios";
 import { useTranslations } from "next-intl";
 import { useParams, useRouter } from "next/navigation";
-import { useActionState } from "react";
+import { useActionState, useState } from "react";
 import { useForm } from "react-hook-form";
 import { z } from "zod";
 
@@ -137,11 +137,21 @@ function ProxyResourceHttpForm({
     });
 
     const [, formAction, saveLoading] = useActionState(onSubmit, null);
+    const [headersValid, setHeadersValid] = useState(true);
 
     async function onSubmit() {
         const isValid = await form.trigger();
         if (!isValid) return;
 
+        if (!headersValid) {
+            toast({
+                variant: "destructive",
+                title: t("settingsErrorUpdate"),
+                description: t("headersValidationError")
+            });
+            return;
+        }
+
         const data = form.getValues();
 
         const res = await api
@@ -318,6 +328,9 @@ function ProxyResourceHttpForm({
                                                         onChange={
                                                             field.onChange
                                                         }
+                                                        onValidityChange={
+                                                            setHeadersValid
+                                                        }
                                                         rows={4}
                                                     />
                                                 </FormControl>
@@ -341,7 +354,7 @@ function ProxyResourceHttpForm({
                 <Button
                     type="submit"
                     loading={saveLoading}
-                    disabled={saveLoading}
+                    disabled={saveLoading || !headersValid}
                     form="http-settings-form"
                 >
                     {t("saveSettings")}

src/components/HeadersInput.tsx

@@ -2,24 +2,36 @@
 
 import { useEffect, useState, useRef } from "react";
 import { Textarea } from "@/components/ui/textarea";
+import { useTranslations } from "next-intl";
 
 interface HeadersInputProps {
     value?: { name: string; value: string }[] | null;
     onChange: (value: { name: string; value: string }[] | null) => void;
+    onValidityChange?: (isValid: boolean) => void;
     placeholder?: string;
     rows?: number;
     className?: string;
 }
 
+// Mirrors the server side validation in updateResource.ts so that invalid
+// input is caught (and shown to the user) before it is ever submitted,
+// instead of being silently dropped in favor of the last known good value.
+const validHeaderNamePattern = /^[a-zA-Z0-9!#$%&'*+\-.^_`|~]+$/;
+const validHeaderValuePattern = /^[\t\x20-\x7E]*$/;
+const templatePattern = /\{\{[^}]+\}\}/;
+
 export function HeadersInput({
     value = [],
     onChange,
+    onValidityChange,
     placeholder = `X-Example-Header: example-value
 X-Another-Header: another-value`,
     rows = 4,
     className
 }: HeadersInputProps) {
+    const t = useTranslations();
     const [internalValue, setInternalValue] = useState("");
+    const [error, setError] = useState<string | null>(null);
     const textareaRef = useRef<HTMLTextAreaElement>(null);
     const isUserEditingRef = useRef(false);
 
@@ -34,37 +46,56 @@ X-Another-Header: another-value`,
             .join("\n");
     };
 
-    // Convert newline-separated string to header objects array
-    const convertToHeadersArray = (
+    // Parse newline-separated text into header objects, validating each line
+    // against the same rules enforced by the server. Returns either the
+    // parsed headers or an error message describing the first invalid line.
+    const parseHeaders = (
         newlineSeparated: string
-    ): { name: string; value: string }[] | null => {
-        if (!newlineSeparated || newlineSeparated.trim() === "") return [];
+    ):
+        | { headers: { name: string; value: string }[]; error: null }
+        | { headers: null; error: string } => {
+        if (!newlineSeparated || newlineSeparated.trim() === "") {
+            return { headers: [], error: null };
+        }
 
-        return newlineSeparated
+        const lines = newlineSeparated
             .split("\n")
             .map((line) => line.trim())
-            .filter((line) => line.length > 0 && line.includes(":"))
-            .map((line) => {
-                const colonIndex = line.indexOf(":");
-                const name = line.substring(0, colonIndex).trim();
-                const value = line.substring(colonIndex + 1).trim();
+            .filter((line) => line.length > 0);
 
-                // Ensure header name conforms to HTTP header requirements
-                // Header names should be case-insensitive, contain only ASCII letters, digits, and hyphens
-                const normalizedName = name
-                    .replace(/[^a-zA-Z0-9\-]/g, "")
-                    .toLowerCase();
+        const headers: { name: string; value: string }[] = [];
 
-                return { name: normalizedName, value };
-            })
-            .filter((header) => header.name.length > 0); // Filter out headers with invalid names
+        for (const line of lines) {
+            const colonIndex = line.indexOf(":");
+            if (colonIndex === -1) {
+                return { headers: null, error: t("headersValidationError") };
+            }
+
+            const name = line.substring(0, colonIndex).trim();
+            const value = line.substring(colonIndex + 1).trim();
+
+            if (
+                !validHeaderNamePattern.test(name) ||
+                !validHeaderValuePattern.test(value) ||
+                templatePattern.test(name) ||
+                templatePattern.test(value)
+            ) {
+                return { headers: null, error: t("headersValidationError") };
+            }
+
+            headers.push({ name, value });
+        }
+
+        return { headers, error: null };
     };
 
     // Update internal value when external value changes
     // But only if the user is not currently editing (textarea not focused)
     useEffect(() => {
         if (!isUserEditingRef.current) {
-            setInternalValue(convertToNewlineSeparated(value));
+            setInternalValue(convertToNewlineSeparated(value ?? []));
+            setError(null);
+            onValidityChange?.(true);
         }
     }, [value]);
 
@@ -75,31 +106,20 @@ X-Another-Header: another-value`,
         // Mark that user is actively editing
         isUserEditingRef.current = true;
 
-        // Only update parent if the input is in a valid state
-        // Valid states: empty/whitespace only, or contains properly formatted headers
+        const result = parseHeaders(newValue);
 
-        if (newValue.trim() === "") {
-            // Empty input is valid - represents no headers
-            onChange([]);
-        } else {
-            // Check if all non-empty lines are properly formatted (contain ':')
-            const lines = newValue.split("\n");
-            const nonEmptyLines = lines
-                .map((line) => line.trim())
-                .filter((line) => line.length > 0);
-
-            // If there are no non-empty lines, or all non-empty lines contain ':', it's valid
-            const isValid =
-                nonEmptyLines.length === 0 ||
-                nonEmptyLines.every((line) => line.includes(":"));
-
-            if (isValid) {
-                // Safe to convert and update parent
-                const headersArray = convertToHeadersArray(newValue);
-                onChange(headersArray);
-            }
-            // If not valid, don't call onChange - let user continue typing
+        if (result.error) {
+            // Surface the error and do not touch the last known good value.
+            // Silently dropping the update here (without telling the user)
+            // is what previously let stale data get saved without warning.
+            setError(result.error);
+            onValidityChange?.(false);
+            return;
         }
+
+        setError(null);
+        onValidityChange?.(true);
+        onChange(result.headers);
     };
 
     const handleFocus = () => {
@@ -114,15 +134,20 @@ X-Another-Header: another-value`,
     };
 
     return (
-        <Textarea
-            ref={textareaRef}
-            value={internalValue}
-            onChange={handleChange}
-            onFocus={handleFocus}
-            onBlur={handleBlur}
-            placeholder={placeholder}
-            rows={rows}
-            className={className}
-        />
+        <div>
+            <Textarea
+                ref={textareaRef}
+                value={internalValue}
+                onChange={handleChange}
+                onFocus={handleFocus}
+                onBlur={handleBlur}
+                placeholder={placeholder}
+                rows={rows}
+                className={className}
+            />
+            {error && (
+                <p className="text-sm text-destructive mt-1.5">{error}</p>
+            )}
+        </div>
     );
 }