From 7e7f6ec3649704fa3f921b0666fc9e0f93e3ee76 Mon Sep 17 00:00:00 2001
From: willclarktech <willclarktech@users.noreply.github.com>
Date: Tue, 4 Aug 2020 16:37:14 +0200
Subject: [PATCH] encoding: Add limit parameters to Bech32.encode and .decode

---
 packages/encoding/src/bech32.spec.ts | 67 +++++++++++++++++++++++++---
 packages/encoding/src/bech32.ts      | 11 +++--
 packages/encoding/types/bech32.d.ts  |  3 +-
 3 files changed, 70 insertions(+), 11 deletions(-)

diff --git a/packages/encoding/src/bech32.spec.ts b/packages/encoding/src/bech32.spec.ts
index 59e6d2c531..da9e6f8290 100644
--- a/packages/encoding/src/bech32.spec.ts
+++ b/packages/encoding/src/bech32.spec.ts
@@ -6,14 +6,69 @@ describe("Bech32", () => {
   // bech32 -e -h eth 9d4e856e572e442f0a4b2763e72d08a0e99d8ded
   const ethAddressRaw = fromHex("9d4e856e572e442f0a4b2763e72d08a0e99d8ded");
 
-  it("encodes", () => {
-    expect(Bech32.encode("eth", ethAddressRaw)).toEqual("eth1n48g2mjh9ezz7zjtya37wtgg5r5emr0drkwlgw");
+  describe("encode", () => {
+    it("works", () => {
+      expect(Bech32.encode("eth", ethAddressRaw)).toEqual("eth1n48g2mjh9ezz7zjtya37wtgg5r5emr0drkwlgw");
+    });
+
+    it("works for very short data", () => {
+      expect(() => Bech32.encode("eth", new Uint8Array(1))).not.toThrow();
+    });
+
+    it("works for very long prefixes", () => {
+      expect(() => Bech32.encode("p".repeat(70), new Uint8Array(20))).toThrowError(/exceeds length limit/i);
+    });
+
+    // See https://github.com/bitcoin/bips/blob/master/bip-0173.mediawiki#Bech32
+    it("works if result is 90 characters", () => {
+      const result = Bech32.encode("eth", new Uint8Array(50));
+      expect(result.length).toEqual(90);
+    });
+
+    it("throws if result exceeds 90 characters", () => {
+      expect(() => Bech32.encode("eth", new Uint8Array(51))).toThrowError(/exceeds length limit/i);
+    });
+
+    it("works if a limit parameter is provided", () => {
+      const limit = 1024;
+      const result = Bech32.encode("eth", new Uint8Array(51), limit);
+      expect(result).toEqual(
+        "eth1qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqug55er",
+      );
+      expect(result.length).toBeGreaterThan(90);
+    });
+
+    it("throws if result exceeds the provided limit parameter", () => {
+      const limit = 10;
+      expect(() => Bech32.encode("eth", ethAddressRaw, limit)).toThrowError(/exceeds length limit/i);
+    });
   });
 
-  it("decodes", () => {
-    expect(Bech32.decode("eth1n48g2mjh9ezz7zjtya37wtgg5r5emr0drkwlgw")).toEqual({
-      prefix: "eth",
-      data: ethAddressRaw,
+  describe("decode", () => {
+    it("works", () => {
+      expect(Bech32.decode("eth1n48g2mjh9ezz7zjtya37wtgg5r5emr0drkwlgw")).toEqual({
+        prefix: "eth",
+        data: ethAddressRaw,
+      });
+    });
+
+    it("works for addresses which exceed the specification limit of 90 characters", () => {
+      // Example from https://github.com/cosmos/cosmos-sdk/pull/6237#issuecomment-658116534
+      expect(() =>
+        Bech32.decode(
+          "cosmospub1ytql0csgqvfzd666axrjzqmn5q2ucztcyxw8hvlzen94ay05tegaerkug5pn3xn8wqdymt598ufzd666axrjzqsxllmwacap3f6xyc4x30jl8ecrcs2tze3zzgxkmthcsqxnqxhwwgfzd666axrjzqs2rlu3wz5gnslgpprszjr8r65n0d6y39q657th77eyvengtk3z0y6h2pnk",
+        ),
+      ).not.toThrow();
+    });
+
+    it("throws for addresses which exceed the specification limit of 90 characters if a limit is specified", () => {
+      // Example from https://github.com/cosmos/cosmos-sdk/pull/6237#issuecomment-658116534
+      expect(() =>
+        Bech32.decode(
+          "cosmospub1ytql0csgqvfzd666axrjzqmn5q2ucztcyxw8hvlzen94ay05tegaerkug5pn3xn8wqdymt598ufzd666axrjzqsxllmwacap3f6xyc4x30jl8ecrcs2tze3zzgxkmthcsqxnqxhwwgfzd666axrjzqs2rlu3wz5gnslgpprszjr8r65n0d6y39q657th77eyvengtk3z0y6h2pnk",
+          90,
+        ),
+      ).toThrowError(/exceeds length limit/i);
     });
   });
 });
diff --git a/packages/encoding/src/bech32.ts b/packages/encoding/src/bech32.ts
index 38fedde429..94d606813e 100644
--- a/packages/encoding/src/bech32.ts
+++ b/packages/encoding/src/bech32.ts
@@ -1,13 +1,16 @@
 import * as bech32 from "bech32";
 
 export class Bech32 {
-  public static encode(prefix: string, data: Uint8Array): string {
-    const address = bech32.encode(prefix, bech32.toWords(data));
+  public static encode(prefix: string, data: Uint8Array, limit?: number): string {
+    const address = bech32.encode(prefix, bech32.toWords(data), limit);
     return address;
   }
 
-  public static decode(address: string): { readonly prefix: string; readonly data: Uint8Array } {
-    const decodedAddress = bech32.decode(address);
+  public static decode(
+    address: string,
+    limit = Infinity,
+  ): { readonly prefix: string; readonly data: Uint8Array } {
+    const decodedAddress = bech32.decode(address, limit);
     return {
       prefix: decodedAddress.prefix,
       data: new Uint8Array(bech32.fromWords(decodedAddress.words)),
diff --git a/packages/encoding/types/bech32.d.ts b/packages/encoding/types/bech32.d.ts
index 8ec29b94ae..9ddd6388df 100644
--- a/packages/encoding/types/bech32.d.ts
+++ b/packages/encoding/types/bech32.d.ts
@@ -1,7 +1,8 @@
 export declare class Bech32 {
-  static encode(prefix: string, data: Uint8Array): string;
+  static encode(prefix: string, data: Uint8Array, limit?: number): string;
   static decode(
     address: string,
+    limit?: number,
   ): {
     readonly prefix: string;
     readonly data: Uint8Array;