From 595283851d8fe3e18553fdb2ad6e773e1a9c1a22 Mon Sep 17 00:00:00 2001
From: Sjors Provoost <sjors@sprovoost.nl>
Date: Wed, 9 Jan 2019 20:16:46 +0100
Subject: [rpc] util: add deriveaddresses method

---
 doc/release-notes-14667.md             |  4 ++
 src/rpc/client.cpp                     |  2 +
 src/rpc/misc.cpp                       | 91 ++++++++++++++++++++++++++++++++++
 test/functional/rpc_deriveaddresses.py | 50 +++++++++++++++++++
 test/functional/test_runner.py         |  2 +
 5 files changed, 149 insertions(+)
 create mode 100644 doc/release-notes-14667.md
 create mode 100755 test/functional/rpc_deriveaddresses.py

diff --git a/doc/release-notes-14667.md b/doc/release-notes-14667.md
new file mode 100644
index 0000000000..5cb1d0aee7
--- /dev/null
+++ b/doc/release-notes-14667.md
@@ -0,0 +1,4 @@
+New RPC methods
+------------
+
+- `deriveaddresses` returns one or more addresses corresponding to an [output descriptor](/doc/descriptors.md).
diff --git a/src/rpc/client.cpp b/src/rpc/client.cpp
index 6f1bfb03d1..3d0a165122 100644
--- a/src/rpc/client.cpp
+++ b/src/rpc/client.cpp
@@ -68,6 +68,8 @@ static const CRPCConvertParam vRPCConvertParams[] =
     { "sendmany", 4, "subtractfeefrom" },
     { "sendmany", 5 , "replaceable" },
     { "sendmany", 6 , "conf_target" },
+    { "deriveaddresses", 1, "begin" },
+    { "deriveaddresses", 2, "end" },
     { "scantxoutset", 1, "scanobjects" },
     { "addmultisigaddress", 0, "nrequired" },
     { "addmultisigaddress", 1, "keys" },
diff --git a/src/rpc/misc.cpp b/src/rpc/misc.cpp
index dc3745858b..70cc96c405 100644
--- a/src/rpc/misc.cpp
+++ b/src/rpc/misc.cpp
@@ -16,6 +16,7 @@
 #include <rpc/blockchain.h>
 #include <rpc/server.h>
 #include <rpc/util.h>
+#include <script/descriptor.h>
 #include <timedata.h>
 #include <util/system.h>
 #include <util/strencodings.h>
@@ -142,6 +143,95 @@ static UniValue createmultisig(const JSONRPCRequest& request)
     return result;
 }
 
+UniValue deriveaddresses(const JSONRPCRequest& request)
+{
+    if (request.fHelp || request.params.empty() || request.params.size() > 3) {
+        throw std::runtime_error(
+            RPCHelpMan{"deriveaddresses",
+            {"\nDerives one or more addresses corresponding to an output descriptor.\n"
+            "Examples of output descriptors are:\n"
+            "    pkh(<pubkey>)                        P2PKH outputs for the given pubkey\n"
+            "    wpkh(<pubkey>)                       Native segwit P2PKH outputs for the given pubkey\n"
+            "    sh(multi(<n>,<pubkey>,<pubkey>,...)) P2SH-multisig outputs for the given threshold and pubkeys\n"
+            "    raw(<hex script>)                    Outputs whose scriptPubKey equals the specified hex scripts\n"
+            "\nIn the above, <pubkey> either refers to a fixed public key in hexadecimal notation, or to an xpub/xprv optionally followed by one\n"
+            "or more path elements separated by \"/\", where \"h\" represents a hardened child key.\n"
+            "For more information on output descriptors, see the documentation in the doc/descriptors.md file.\n"},
+            {
+                {"descriptor", RPCArg::Type::STR, /* opt */ false, /* default_val */ "", "The descriptor."},
+                {"begin", RPCArg::Type::NUM, /* opt */ true, /* default_val */ "", "If a ranged descriptor is used, this specifies the beginning of the range to import."},
+                {"end", RPCArg::Type::NUM, /* opt */ true, /* default_val */ "", "If a ranged descriptor is used, this specifies the end of the range to import."}
+            },
+            RPCResult{
+                "[ address ] (array) the derived addresses\n"
+            },
+            RPCExamples{
+                "First three native segwit receive addresses\n" +
+                HelpExampleCli("deriveaddresses", "\"wpkh([d34db33f/84h/0h/0h]xpub6DJ2dNUysrn5Vt36jH2KLBT2i1auw1tTSSomg8PhqNiUtx8QX2SvC9nrHu81fT41fvDUnhMjEzQgXnQjKEu3oaqMSzhSrHMxyyoEAmUHQbY/0/*)\" 0 2")
+            }}.ToString()
+        );
+    }
+
+    RPCTypeCheck(request.params, {UniValue::VSTR, UniValue::VNUM, UniValue::VNUM});
+    const std::string desc_str = request.params[0].get_str();
+
+    int range_begin = 0;
+    int range_end = 0;
+
+    if (request.params.size() >= 2) {
+        if (request.params.size() == 2) {
+            throw JSONRPCError(RPC_INVALID_PARAMETER, "Missing range end parameter");
+        }
+        range_begin = request.params[1].get_int();
+        range_end = request.params[2].get_int();
+        if (range_begin < 0) {
+            throw JSONRPCError(RPC_INVALID_PARAMETER, "Range should be greater or equal than 0");
+        }
+        if (range_begin > range_end) {
+            throw JSONRPCError(RPC_INVALID_PARAMETER, "Range end should be equal to or greater than begin");
+        }
+    }
+
+    FlatSigningProvider provider;
+    auto desc = Parse(desc_str, provider);
+    if (!desc) {
+        throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, strprintf("Invalid descriptor"));
+    }
+
+    if (!desc->IsRange() && request.params.size() > 1) {
+        throw JSONRPCError(RPC_INVALID_PARAMETER, "Range should not be specified for an un-ranged descriptor");
+    }
+
+    if (desc->IsRange() && request.params.size() == 1) {
+        throw JSONRPCError(RPC_INVALID_PARAMETER, "Range must be specified for a ranged descriptor");
+    }
+
+    UniValue addresses(UniValue::VARR);
+
+    for (int i = range_begin; i <= range_end; ++i) {
+        std::vector<CScript> scripts;
+        if (!desc->Expand(i, provider, scripts, provider)) {
+            throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, strprintf("Cannot derive script without private keys"));
+        }
+
+        for (const CScript &script : scripts) {
+            CTxDestination dest;
+            if (!ExtractDestination(script, dest)) {
+                throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, strprintf("Descriptor does not have a corresponding address"));
+            }
+
+            addresses.push_back(EncodeDestination(dest));
+        }
+    }
+
+    // This should not be possible, but an assert seems overkill:
+    if (addresses.empty()) {
+        throw JSONRPCError(RPC_MISC_ERROR, "Unexpected empty result");
+    }
+
+    return addresses;
+}
+
 static UniValue verifymessage(const JSONRPCRequest& request)
 {
     if (request.fHelp || request.params.size() != 3)
@@ -473,6 +563,7 @@ static const CRPCCommand commands[] =
     { "control",            "logging",                &logging,                {"include", "exclude"}},
     { "util",               "validateaddress",        &validateaddress,        {"address"} },
     { "util",               "createmultisig",         &createmultisig,         {"nrequired","keys","address_type"} },
+    { "util",               "deriveaddresses",        &deriveaddresses,        {"descriptor", "begin", "end"} },
     { "util",               "verifymessage",          &verifymessage,          {"address","signature","message"} },
     { "util",               "signmessagewithprivkey", &signmessagewithprivkey, {"privkey","message"} },
 
diff --git a/test/functional/rpc_deriveaddresses.py b/test/functional/rpc_deriveaddresses.py
new file mode 100755
index 0000000000..2cc5bc974b
--- /dev/null
+++ b/test/functional/rpc_deriveaddresses.py
@@ -0,0 +1,50 @@
+#!/usr/bin/env python3
+# Copyright (c) 2018 The Bitcoin Core developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
+"""Test the deriveaddresses rpc call."""
+from test_framework.test_framework import BitcoinTestFramework
+from test_framework.util import assert_equal, assert_raises_rpc_error
+
+class DeriveaddressesTest(BitcoinTestFramework):
+    def set_test_params(self):
+        self.num_nodes = 1
+        self.supports_cli = 1
+
+    def run_test(self):
+        assert_raises_rpc_error(-5, "Invalid descriptor", self.nodes[0].deriveaddresses, "a")
+
+        descriptor = "wpkh(tprv8ZgxMBicQKsPd7Uf69XL1XwhmjHopUGep8GuEiJDZmbQz6o58LninorQAfcKZWARbtRtfnLcJ5MQ2AtHcQJCCRUcMRvmDUjyEmNUWwx8UbK/1/1/0)"
+        address = "bcrt1qjqmxmkpmxt80xz4y3746zgt0q3u3ferr34acd5"
+
+        assert_equal(self.nodes[0].deriveaddresses(descriptor), [address])
+
+        descriptor_pubkey = "wpkh(tpubD6NzVbkrYhZ4WaWSyoBvQwbpLkojyoTZPRsgXELWz3Popb3qkjcJyJUGLnL4qHHoQvao8ESaAstxYSnhyswJ76uZPStJRJCTKvosUCJZL5B/1/1/0)"
+        address = "bcrt1qjqmxmkpmxt80xz4y3746zgt0q3u3ferr34acd5"
+
+        assert_equal(self.nodes[0].deriveaddresses(descriptor_pubkey), [address])
+
+        ranged_descriptor = "wpkh(tprv8ZgxMBicQKsPd7Uf69XL1XwhmjHopUGep8GuEiJDZmbQz6o58LninorQAfcKZWARbtRtfnLcJ5MQ2AtHcQJCCRUcMRvmDUjyEmNUWwx8UbK/1/1/*)"
+        assert_equal(self.nodes[0].deriveaddresses(ranged_descriptor, 0, 2), [address, "bcrt1qhku5rq7jz8ulufe2y6fkcpnlvpsta7rq4442dy", "bcrt1qpgptk2gvshyl0s9lqshsmx932l9ccsv265tvaq"])
+
+        assert_raises_rpc_error(-8, "Range should not be specified for an un-ranged descriptor", self.nodes[0].deriveaddresses, "wpkh(tprv8ZgxMBicQKsPd7Uf69XL1XwhmjHopUGep8GuEiJDZmbQz6o58LninorQAfcKZWARbtRtfnLcJ5MQ2AtHcQJCCRUcMRvmDUjyEmNUWwx8UbK/1/1/0)", 0, 2)
+
+        assert_raises_rpc_error(-8, "Range must be specified for a ranged descriptor", self.nodes[0].deriveaddresses, "wpkh(tprv8ZgxMBicQKsPd7Uf69XL1XwhmjHopUGep8GuEiJDZmbQz6o58LninorQAfcKZWARbtRtfnLcJ5MQ2AtHcQJCCRUcMRvmDUjyEmNUWwx8UbK/1/1/*)")
+
+        assert_raises_rpc_error(-8, "Missing range end parameter", self.nodes[0].deriveaddresses, "wpkh(tprv8ZgxMBicQKsPd7Uf69XL1XwhmjHopUGep8GuEiJDZmbQz6o58LninorQAfcKZWARbtRtfnLcJ5MQ2AtHcQJCCRUcMRvmDUjyEmNUWwx8UbK/1/1/*)", 0)
+
+        assert_raises_rpc_error(-8, "Range end should be equal to or greater than begin", self.nodes[0].deriveaddresses, "wpkh(tprv8ZgxMBicQKsPd7Uf69XL1XwhmjHopUGep8GuEiJDZmbQz6o58LninorQAfcKZWARbtRtfnLcJ5MQ2AtHcQJCCRUcMRvmDUjyEmNUWwx8UbK/1/1/*)", 2, 0)
+
+        assert_raises_rpc_error(-8, "Range should be greater or equal than 0", self.nodes[0].deriveaddresses, "wpkh(tprv8ZgxMBicQKsPd7Uf69XL1XwhmjHopUGep8GuEiJDZmbQz6o58LninorQAfcKZWARbtRtfnLcJ5MQ2AtHcQJCCRUcMRvmDUjyEmNUWwx8UbK/1/1/*)", -1, 0)
+
+        combo_descriptor = "combo(tprv8ZgxMBicQKsPd7Uf69XL1XwhmjHopUGep8GuEiJDZmbQz6o58LninorQAfcKZWARbtRtfnLcJ5MQ2AtHcQJCCRUcMRvmDUjyEmNUWwx8UbK/1/1/0)"
+        assert_equal(self.nodes[0].deriveaddresses(combo_descriptor), ["mtfUoUax9L4tzXARpw1oTGxWyoogp52KhJ", "mtfUoUax9L4tzXARpw1oTGxWyoogp52KhJ", address, "2NDvEwGfpEqJWfybzpKPHF2XH3jwoQV3D7x"])
+
+        hardened_without_privkey_descriptor = "wpkh(tpubD6NzVbkrYhZ4WaWSyoBvQwbpLkojyoTZPRsgXELWz3Popb3qkjcJyJUGLnL4qHHoQvao8ESaAstxYSnhyswJ76uZPStJRJCTKvosUCJZL5B/1'/1/0)"
+        assert_raises_rpc_error(-5, "Cannot derive script without private keys", self.nodes[0].deriveaddresses, hardened_without_privkey_descriptor)
+
+        bare_multisig_descriptor = "multi(1, tpubD6NzVbkrYhZ4WaWSyoBvQwbpLkojyoTZPRsgXELWz3Popb3qkjcJyJUGLnL4qHHoQvao8ESaAstxYSnhyswJ76uZPStJRJCTKvosUCJZL5B/1/1/0, tpubD6NzVbkrYhZ4WaWSyoBvQwbpLkojyoTZPRsgXELWz3Popb3qkjcJyJUGLnL4qHHoQvao8ESaAstxYSnhyswJ76uZPStJRJCTKvosUCJZL5B/1/1/1)"
+        assert_raises_rpc_error(-5, "Descriptor does not have a corresponding address", self.nodes[0].deriveaddresses, bare_multisig_descriptor)
+
+if __name__ == '__main__':
+    DeriveaddressesTest().main()
diff --git a/test/functional/test_runner.py b/test/functional/test_runner.py
index 8c6f6706e7..3ddd5a299a 100755
--- a/test/functional/test_runner.py
+++ b/test/functional/test_runner.py
@@ -181,6 +181,8 @@ BASE_SCRIPTS = [
     'feature_filelock.py',
     'p2p_unrequested_blocks.py',
     'feature_includeconf.py',
+    'rpc_deriveaddresses.py',
+    'rpc_deriveaddresses.py --usecli',
     'rpc_scantxoutset.py',
     'feature_logging.py',
     'p2p_node_network_limited.py',
-- 
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