From d391782cd9d726634b64ebdbdc1fa0c7ea7f56c1 Mon Sep 17 00:00:00 2001
From: Gregory Sanders <gsanders87@gmail.com>
Date: Mon, 17 Dec 2018 17:15:27 -0500
Subject: [PATCH] Add getwalletpakinfo RPC call

---
 src/wallet/rpcdump.cpp   | 50 ++++++++++++++++++++++++++++++++++++++++
 src/wallet/rpcwallet.cpp |  2 ++
 2 files changed, 52 insertions(+)

diff --git a/src/wallet/rpcdump.cpp b/src/wallet/rpcdump.cpp
index 5800e75827..bf9a03f50b 100644
--- a/src/wallet/rpcdump.cpp
+++ b/src/wallet/rpcdump.cpp
@@ -1275,3 +1275,53 @@ UniValue importmulti(const JSONRPCRequest& mainRequest)
 
     return response;
 }
+
+extern CTxDestination DeriveBitcoinOfflineAddress(const CExtPubKey& xpub, const uint32_t counter);
+
+UniValue getwalletpakinfo(const JSONRPCRequest& request)
+{
+    std::shared_ptr<CWallet> const wallet = GetWalletForJSONRPCRequest(request);
+    CWallet* const pwallet = wallet.get();
+
+    if (!EnsureWalletIsAvailable(pwallet, request.fHelp)) {
+        return NullUniValue;
+    }
+
+    if (request.fHelp || request.params.size() != 0)
+        throw std::runtime_error(
+            "getwalletpakinfo\n"
+            "\nReturns relevant pegout authorization key (PAK) information about this wallet. Throws an error if initpegoutwallet` has not been invoked on this wallet.\n"
+            "\nResult:\n"
+            "{\n"
+                "\"derivation_path\"  (string) The next index to be used by the wallet for `sendtomainchain`.\n"
+                "\"bitcoin_xpub\"     (string) The Bitcoin xpubkey loaded in the wallet for pegouts.\n"
+                "\"liquid_pak\"       (string) Pubkey in hex corresponding to the Liquid PAK loaded in the wallet for pegouts.\n"
+                "\"liquid_pak_address\" (string) The corresponding address for `liquid_pak`. Useful for `dumpprivkey` for wallet backup or transfer.\n"
+                "\"address_lookahead\"(array)  The three next Bitcoin addresses the wallet will use for `sendtomainchain` based on the internal counter.\n"
+            "}\n"
+        );
+
+    LOCK2(cs_main, pwallet->cs_wallet);
+
+    if (pwallet->offline_counter == -1) {
+        throw JSONRPCError(RPC_MISC_ERROR, "This wallet has not been initialized for PAK-enforced peg-outs.");
+    }
+
+    UniValue ret(UniValue::VOBJ);
+    std::stringstream ss;
+    ss << pwallet->offline_counter;
+    ret.push_back(Pair("derivation_path", "/0/"+ss.str()));
+
+    CExtPubKey& xpub = pwallet->offline_xpub;
+
+    ret.pushKV("bitcoin_xpub", EncodeExtPubKey(xpub));
+    ret.pushKV("liquid_pak", HexStr(pwallet->online_key));
+    ret.pushKV("liquid_pak_address", EncodeDestination((pwallet->online_key.GetID())));
+
+    UniValue address_list(UniValue::VARR);
+    for (unsigned int i = 0; i < 3; i++) {
+        address_list.push_back(EncodeParentDestination(DeriveBitcoinOfflineAddress(xpub, pwallet->offline_counter+i)));
+    }
+    ret.push_back(Pair("address_lookahead", address_list));
+    return ret;
+}
diff --git a/src/wallet/rpcwallet.cpp b/src/wallet/rpcwallet.cpp
index 9eed789078..639fb14507 100644
--- a/src/wallet/rpcwallet.cpp
+++ b/src/wallet/rpcwallet.cpp
@@ -5648,6 +5648,7 @@ extern UniValue importprunedfunds(const JSONRPCRequest& request);
 extern UniValue removeprunedfunds(const JSONRPCRequest& request);
 extern UniValue importmulti(const JSONRPCRequest& request);
 extern UniValue rescanblockchain(const JSONRPCRequest& request);
+extern UniValue getwalletpakinfo(const JSONRPCRequest& request);
 
 static const CRPCCommand commands[] =
 { //  category              name                                actor (function)                argNames
@@ -5708,6 +5709,7 @@ static const CRPCCommand commands[] =
     { "wallet",             "createrawpegin",                   &createrawpegin,                {"bitcoin_tx", "txoutproof", "claim_script"} },
     { "wallet",             "sendtomainchain",                  &sendtomainchain,               {"address", "amount", "subtractfeefromamount"} },
     { "wallet",             "initpegoutwallet",                 &initpegoutwallet,              {"bitcoin_xpub", "bip32_counter", "liquid_pak"} },
+    { "wallet",             "getwalletpakinfo",                 &getwalletpakinfo,              {} },
 
 
     /** Account functions (deprecated) */