From c66543976aa8171be6ea0c0771b1e9447a857c40 Mon Sep 17 00:00:00 2001
From: Trent Nelson <trent@solana.com>
Date: Fri, 24 Apr 2020 14:05:31 -0600
Subject: [PATCH] Add an example for interacting with the app using Javascript
 (#118)

---
 examples/example-sign.js | 139 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 139 insertions(+)
 create mode 100644 examples/example-sign.js

diff --git a/examples/example-sign.js b/examples/example-sign.js
new file mode 100644
index 00000000..26616feb
--- /dev/null
+++ b/examples/example-sign.js
@@ -0,0 +1,139 @@
+const Transport = require("@ledgerhq/hw-transport-node-hid").default;
+const bs58 = require("bs58");
+const nacl = require("tweetnacl");
+const solana = require("@solana/web3.js");
+const assert = require("assert");
+
+const INS_GET_PUBKEY = 0x05;
+const INS_SIGN_MESSAGE = 0x06;
+
+const P1_NON_CONFIRM = 0x00;
+const P1_CONFIRM = 0x01;
+
+const P2_EXTEND = 0x01;
+const P2_MORE = 0x02;
+
+const MAX_PAYLOAD = 255;
+
+const LEDGER_CLA = 0xe0;
+
+const STATUS_OK = 0x9000;
+
+/*
+ * Helper for chunked send of large payloads
+ */
+async function solana_send(transport, instruction, p1, payload) {
+  var p2 = 0;
+  var payload_offset = 0;
+
+  if (payload.length > MAX_PAYLOAD) {
+    while ((payload.length - payload_offset) > MAX_PAYLOAD) {
+      const buf = payload.slice(payload_offset, payload_offset + MAX_PAYLOAD);
+      payload_offset += MAX_PAYLOAD;
+      console.log("send", (p2 | P2_MORE).toString(16), buf.length.toString(16), buf);
+      const reply = await transport.send(LEDGER_CLA, instruction, p1, (p2 | P2_MORE), buf);
+      if (reply.length != 2) {
+        throw new TransportError(
+          "solana_send: Received unexpected reply payload",
+          "UnexpectedReplyPayload"
+        );
+      }
+      p2 |= P2_EXTEND;
+    }
+  }
+
+  const buf = payload.slice(payload_offset);
+  console.log("send", p2.toString(16), buf.length.toString(16), buf);
+  const reply = await transport.send(LEDGER_CLA, instruction, p1, p2, buf);
+
+  return reply.slice(0, reply.length - 2);
+}
+
+const BIP32_HARDENED_BIT = ((1 << 31) >>> 0);
+function _harden(n) {
+  return (n | BIP32_HARDENED_BIT) >>> 0;
+}
+
+function solana_derivation_path(account, change) {
+  var length;
+  if (typeof(account) === 'number') {
+    if (typeof(change) === 'number') {
+      length = 4;
+    } else {
+      length = 3;
+    }
+  } else {
+    length = 2;
+  }
+
+  var derivation_path = Buffer.alloc(1 + (length * 4));
+  var offset = 0;
+  offset = derivation_path.writeUInt8(length, offset);
+  offset = derivation_path.writeUInt32BE(_harden(44), offset);  // Using BIP44
+  offset = derivation_path.writeUInt32BE(_harden(501), offset); // Solana's BIP44 path
+
+  if (length > 2) {
+    offset = derivation_path.writeUInt32BE(_harden(account), offset);
+    if (length == 4) {
+      offset = derivation_path.writeUInt32BE(_harden(change), offset);
+    }
+  }
+
+  return derivation_path;
+}
+
+async function solana_ledger_get_pubkey(transport, derivation_path) {
+  return solana_send(transport, INS_GET_PUBKEY, P1_NON_CONFIRM, derivation_path);
+}
+
+async function solana_ledger_sign_transaction(transport, derivation_path, transaction) {
+  const msg_bytes = transaction.serializeMessage();
+
+
+  // XXX: Ledger app only supports a single derivation_path per call ATM
+  var num_paths = Buffer.alloc(1);
+  num_paths.writeUInt8(1);
+
+  const payload = Buffer.concat([num_paths, derivation_path, msg_bytes]);
+
+  return solana_send(transport, INS_SIGN_MESSAGE, P1_CONFIRM, payload);
+}
+
+( async () => {
+  var transport = await Transport.create();
+
+  const from_derivation_path = solana_derivation_path();
+  const from_pubkey_bytes = await solana_ledger_get_pubkey(transport, from_derivation_path);
+  const from_pubkey_string = bs58.encode(from_pubkey_bytes);
+  console.log("---", from_pubkey_string);
+
+  const to_derivation_path = solana_derivation_path(1);
+  const to_pubkey_bytes = await solana_ledger_get_pubkey(transport, to_derivation_path);
+  const to_pubkey_string = bs58.encode(to_pubkey_bytes);
+  console.log("---", to_pubkey_string);
+
+  const from_pubkey = new solana.PublicKey(from_pubkey_string);
+  const to_pubkey = new solana.PublicKey(to_pubkey_string);
+  var tx = solana.SystemProgram.transfer({
+    fromPubkey: from_pubkey,
+    toPubkey: to_pubkey,
+    lamports: 42,
+  })
+
+  // XXX: Fake blockhash so this example doesn't need a
+  // network connection. It should be queried from the
+  // cluster in normal use.
+  tx.recentBlockhash = bs58.encode(Buffer.from([
+    3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
+      3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,
+  ]));
+
+  const sig_bytes = await solana_ledger_sign_transaction(transport, from_derivation_path, tx);
+
+  const sig_string = bs58.encode(sig_bytes);
+  console.log("--- len:", sig_bytes.length, "sig:", sig_string);
+
+  tx.addSignature(from_pubkey, sig_bytes);
+  console.log("--- verifies:", tx.verifySignatures());
+})().catch(e => console.log(e) );
+