From c05723ca6ad4f17b823662e83ed8b442fe10626a Mon Sep 17 00:00:00 2001
From: MeiMei <30769358+mei23@users.noreply.github.com>
Date: Tue, 31 May 2022 17:44:22 +0900
Subject: Fix IP address rate limit (#8758)

* Fix IP address rate limit

* CHANGELOG

* Tune getIpHash
---
 packages/backend/src/misc/get-ip-hash.ts | 9 +++++++++
 1 file changed, 9 insertions(+)
 create mode 100644 packages/backend/src/misc/get-ip-hash.ts

(limited to 'packages/backend/src/misc')

diff --git a/packages/backend/src/misc/get-ip-hash.ts b/packages/backend/src/misc/get-ip-hash.ts
new file mode 100644
index 0000000000..379325bb13
--- /dev/null
+++ b/packages/backend/src/misc/get-ip-hash.ts
@@ -0,0 +1,9 @@
+import IPCIDR from 'ip-cidr';
+
+export function getIpHash(ip: string) {
+	// because a single person may control many IPv6 addresses,
+	// only a /64 subnet prefix of any IP will be taken into account.
+	// (this means for IPv4 the entire address is used)
+	const prefix = IPCIDR.createAddress(ip).mask(64);
+	return 'ip-' + BigInt('0b' + prefix).toString(36);
+}
-- 
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