Como limitar a taxa de envios de formulário

<form action="https://ikiform.com/f/frm_xxxxxxxxxxxxxxxx" method="POST">
  <label for="email">Email</label>
  <input id="email" name="email" type="email" required />
  <label for="message">Message</label>
  <textarea id="message" name="message" required></textarea>
  <button>Send</button>
</form>

"use server";

import { headers } from "next/headers";
import { allow } from "@/lib/limit";

export async function sendMessage(_previous: { message: string }, formData: FormData) {
  const forwarded = (await headers()).get("x-forwarded-for");
  const limit = await allow(forwarded?.split(",")[0]?.trim());
  if (!limit.ok) return { message: `Too many messages. Try again in ${limit.retryAfter} seconds.` };
  await saveMessage(Object.fromEntries(formData));
  return { message: "Thanks. We'll reply by email." };
}

import { ActionError, defineAction } from "astro:actions";
import { z } from "astro/zod";
import { allow } from "../lib/limit";

export const server = {
  sendMessage: defineAction({
    accept: "form",
    input: z.object({ email: z.email(), message: z.string().min(1) }),
    handler: async (input, context) => {
      const limit = await allow(context.clientAddress);
      if (!limit.ok) {
        throw new ActionError({ code: "TOO_MANY_REQUESTS", message: `Too many messages. Try again in ${limit.retryAfter} seconds.` });
      }
      await saveMessage(input);
      return { sent: true };
    },
  }),
};

import { createServerFn } from "@tanstack/react-start";
import { getRequestHeader, setResponseHeaders, setResponseStatus } from "@tanstack/react-start/server";
import { allow } from "../lib/limit";

export const sendMessage = createServerFn({ method: "POST" })
  .validator((data: unknown) => {
    if (!(data instanceof FormData)) throw new Error("Expected form data");
    return { email: String(data.get("email") ?? ""), message: String(data.get("message") ?? "") };
  })
  .handler(async ({ data }) => {
    const limit = await allow(getRequestHeader("x-forwarded-for")?.split(",")[0]?.trim());
    if (!limit.ok) {
      setResponseStatus(429);
      setResponseHeaders(new Headers({ "Retry-After": String(limit.retryAfter) }));
      return { ok: false, message: `Too many messages. Try again in ${limit.retryAfter} seconds.` };
    }
    await saveMessage(data);
    return { ok: true, message: "Thanks. We'll reply by email." };
  });

import { data } from "react-router";
import { allow } from "../lib/limit";
import type { Route } from "./+types/contact";

export async function action({ request }: Route.ActionArgs) {
  const limit = await allow(request.headers.get("x-forwarded-for")?.split(",")[0]?.trim());
  if (!limit.ok) {
    return data(
      { message: `Too many messages. Try again in ${limit.retryAfter} seconds.` },
      { status: 429, headers: { "Retry-After": String(limit.retryAfter) } },
    );
  }
  await saveMessage(Object.fromEntries(await request.formData()));
  return { message: "Thanks. We'll reply by email." };
}

import { fail } from "@sveltejs/kit";
import { allow } from "#lib/limit.js";
import type { Actions } from "./$types";

export const actions = {
  default: async ({ request, getClientAddress }) => {
    const limit = await allow(getClientAddress());
    if (!limit.ok) return fail(429, { message: `Too many messages. Try again in ${limit.retryAfter} seconds.` });
    await saveMessage(Object.fromEntries(await request.formData()));
    return { sent: true };
  },
} satisfies Actions;

export default defineEventHandler(async (event) => {
  const limit = await allow(getRequestIP(event, { xForwardedFor: true }));
  if (!limit.ok) {
    setResponseHeader(event, "Retry-After", limit.retryAfter);
    throw createError({ status: 429, message: `Too many messages. Try again in ${limit.retryAfter} seconds.` });
  }
  await saveMessage(await readBody(event));
  return { sent: true };
});

const button = form.querySelector("button");
const status = form.querySelector("[role=status]");

form.addEventListener("submit", async (event) => {
  event.preventDefault();
  const response = await fetch("https://ikiform.com/f/frm_xxxxxxxxxxxxxxxx", {
    method: "POST",
    headers: { Accept: "application/json" },
    body: new FormData(form),
  });
  const retryAfter = response.headers.get("Retry-After");
  if (response.status === 429 && retryAfter) {
    let wait = Number(retryAfter);
    button.disabled = true;
    const timer = setInterval(() => {
      status.textContent = `Too many messages. Try again in ${wait} seconds.`;
      wait -= 1;
      if (wait < 0) {
        clearInterval(timer);
        button.disabled = false;
        status.textContent = "";
      }
    }, 1000);
    return;
  }
  const result = await response.json();
  status.textContent = result.ok ? "Thanks. We'll reply by email." : result.error.message;
});

<script setup lang="ts">
import { onBeforeUnmount, ref } from "vue";

const ENDPOINT = "https://ikiform.com/f/frm_xxxxxxxxxxxxxxxx";
const wait = ref(0);
const notice = ref("");
let timer: ReturnType<typeof setInterval> | undefined;

function countDown(seconds: number) {
  wait.value = seconds;
  clearInterval(timer);
  timer = setInterval(() => {
    wait.value -= 1;
    if (wait.value <= 0) clearInterval(timer);
  }, 1000);
}

async function send(event: SubmitEvent) {
  notice.value = "";
  const response = await fetch(ENDPOINT, {
    method: "POST",
    headers: { Accept: "application/json" },
    body: new FormData(event.target as HTMLFormElement),
  });
  const retryAfter = Number(response.headers.get("Retry-After"));
  if (response.status === 429 && retryAfter > 0) {
    countDown(retryAfter);
    return;
  }
  const result = await response.json();
  notice.value = result.ok ? "Thanks. We'll reply by email." : result.error.message;
}

onBeforeUnmount(() => clearInterval(timer));
</script>

<template>
  <form :action="ENDPOINT" method="post" @submit.prevent="send">
    <label for="email">Email</label>
    <input id="email" name="email" type="email" required />
    <label for="message">Message</label>
    <textarea id="message" name="message" required />
    <p role="status">{{ wait > 0 ? `Too many messages. Try again in ${wait} seconds.` : notice }}</p>
    <button :disabled="wait > 0">Send</button>
  </form>
</template>