From 9f48053d8f9a1feacc96d7e2a00c8a3a67576948 Mon Sep 17 00:00:00 2001
From: MeshCollider <dobsonsa68@gmail.com>
Date: Thu, 13 Dec 2018 13:55:48 +1300
Subject: [PATCH] [wallet] Allow descriptor imports with importmulti

---
 src/wallet/rpcdump.cpp | 118 ++++++++++++++++++++++++++++++++++++++---
 1 file changed, 111 insertions(+), 7 deletions(-)

diff --git a/src/wallet/rpcdump.cpp b/src/wallet/rpcdump.cpp
index f91d545a3b..9ed2a16416 100644
--- a/src/wallet/rpcdump.cpp
+++ b/src/wallet/rpcdump.cpp
@@ -9,6 +9,7 @@
 #include <merkleblock.h>
 #include <rpc/server.h>
 #include <rpc/util.h>
+#include <script/descriptor.h>
 #include <script/script.h>
 #include <script/standard.h>
 #include <sync.h>
@@ -984,11 +985,14 @@ static UniValue ProcessImportLegacy(ImportData& import_data, std::map<CKeyID, CP
     const bool internal = data.exists("internal") ? data["internal"].get_bool() : false;
     const bool watchOnly = data.exists("watchonly") ? data["watchonly"].get_bool() : false;
 
+    if (data.exists("range")) {
+        throw JSONRPCError(RPC_INVALID_PARAMETER, "Range should not be specified for a non-descriptor import");
+    }
+
     // Generate the script and destination for the scriptPubKey provided
     CScript script;
-    CTxDestination dest;
     if (!isScript) {
-        dest = DecodeDestination(output);
+        CTxDestination dest = DecodeDestination(output);
         if (!IsValidDestination(dest)) {
             throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Invalid address \"" + output + "\"");
         }
@@ -999,6 +1003,7 @@ static UniValue ProcessImportLegacy(ImportData& import_data, std::map<CKeyID, CP
         }
         std::vector<unsigned char> vData(ParseHex(output));
         script = CScript(vData.begin(), vData.end());
+        CTxDestination dest;
         if (!ExtractDestination(script, dest) && !internal) {
             throw JSONRPCError(RPC_INVALID_PARAMETER, "Internal must be set to true for nonstandard scriptPubKey imports.");
         }
@@ -1103,6 +1108,91 @@ static UniValue ProcessImportLegacy(ImportData& import_data, std::map<CKeyID, CP
     return warnings;
 }
 
+static UniValue ProcessImportDescriptor(ImportData& import_data, std::map<CKeyID, CPubKey>& pubkey_map, std::map<CKeyID, CKey>& privkey_map, std::set<CScript>& script_pub_keys, bool& have_solving_data, const UniValue& data)
+{
+    UniValue warnings(UniValue::VARR);
+
+    const std::string& descriptor = data["desc"].get_str();
+    FlatSigningProvider keys;
+    auto parsed_desc = Parse(descriptor, keys);
+    if (!parsed_desc) {
+        throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Descriptor is invalid");
+    }
+
+    have_solving_data = parsed_desc->IsSolvable();
+    const bool watch_only = data.exists("watchonly") ? data["watchonly"].get_bool() : false;
+
+    int64_t range_start = 0, range_end = 0;
+    if (!parsed_desc->IsRange() && data.exists("range")) {
+        throw JSONRPCError(RPC_INVALID_PARAMETER, "Range should not be specified for an un-ranged descriptor");
+    } else if (parsed_desc->IsRange()) {
+        if (!data.exists("range")) {
+            throw JSONRPCError(RPC_INVALID_PARAMETER, "Descriptor is ranged, please specify the range");
+        }
+        const UniValue& range = data["range"];
+        range_start = range.exists("start") ? range["start"].get_int64() : 0;
+        if (!range.exists("end")) {
+            throw JSONRPCError(RPC_INVALID_PARAMETER, "End of range for descriptor must be specified");
+        }
+        range_end = range["end"].get_int64();
+        if (range_end < range_start || range_start < 0) {
+            throw JSONRPCError(RPC_INVALID_PARAMETER, "Invalid descriptor range specified");
+        }
+    }
+
+    const UniValue& priv_keys = data.exists("keys") ? data["keys"].get_array() : UniValue();
+
+    FlatSigningProvider out_keys;
+
+    // Expand all descriptors to get public keys and scripts.
+    // TODO: get private keys from descriptors too
+    for (int i = range_start; i <= range_end; ++i) {
+        std::vector<CScript> scripts_temp;
+        parsed_desc->Expand(i, keys, scripts_temp, out_keys);
+        std::copy(scripts_temp.begin(), scripts_temp.end(), std::inserter(script_pub_keys, script_pub_keys.end()));
+    }
+
+    for (const auto& x : out_keys.scripts) {
+        import_data.import_scripts.emplace(x.second);
+    }
+
+    std::copy(out_keys.pubkeys.begin(), out_keys.pubkeys.end(), std::inserter(pubkey_map, pubkey_map.end()));
+
+    for (size_t i = 0; i < priv_keys.size(); ++i) {
+        const auto& str = priv_keys[i].get_str();
+        CKey key = DecodeSecret(str);
+        if (!key.IsValid()) {
+            throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Invalid private key encoding");
+        }
+        CPubKey pubkey = key.GetPubKey();
+        CKeyID id = pubkey.GetID();
+
+        // Check if this private key corresponds to a public key from the descriptor
+        if (!pubkey_map.count(id)) {
+            warnings.push_back("Ignoring irrelevant private key.");
+        } else {
+            privkey_map.emplace(id, key);
+        }
+    }
+
+    // Check if all the public keys have corresponding private keys in the import for spendability.
+    // This does not take into account threshold multisigs which could be spendable without all keys.
+    // Thus, threshold multisigs without all keys will be considered not spendable here, even if they are,
+    // perhaps triggering a false warning message. This is consistent with the current wallet IsMine check.
+    bool spendable = std::all_of(pubkey_map.begin(), pubkey_map.end(),
+        [&](const std::pair<CKeyID, CPubKey>& used_key) {
+            return privkey_map.count(used_key.first) > 0;
+        });
+    if (!watch_only && !spendable) {
+        warnings.push_back("Some private keys are missing, outputs will be considered watchonly. If this is intentional, specify the watchonly flag.");
+    }
+    if (watch_only && spendable) {
+        warnings.push_back("All private keys are provided, outputs will be considered spendable. If this is intentional, do not specify the watchonly flag.");
+    }
+
+    return warnings;
+}
+
 static UniValue ProcessImport(CWallet * const pwallet, const UniValue& data, const int64_t timestamp) EXCLUSIVE_LOCKS_REQUIRED(pwallet->cs_wallet)
 {
     UniValue warnings(UniValue::VARR);
@@ -1122,7 +1212,15 @@ static UniValue ProcessImport(CWallet * const pwallet, const UniValue& data, con
         std::set<CScript> script_pub_keys;
         bool have_solving_data;
 
-        warnings = ProcessImportLegacy(import_data, pubkey_map, privkey_map, script_pub_keys, have_solving_data, data);
+        if (data.exists("scriptPubKey") && data.exists("desc")) {
+            throw JSONRPCError(RPC_INVALID_PARAMETER, "Both a descriptor and a scriptPubKey should not be provided.");
+        } else if (data.exists("scriptPubKey")) {
+            warnings = ProcessImportLegacy(import_data, pubkey_map, privkey_map, script_pub_keys, have_solving_data, data);
+        } else if (data.exists("desc")) {
+            warnings = ProcessImportDescriptor(import_data, pubkey_map, privkey_map, script_pub_keys, have_solving_data, data);
+        } else {
+            throw JSONRPCError(RPC_INVALID_PARAMETER, "Either a descriptor or scriptPubKey must be provided.");
+        }
 
         // If private keys are disabled, abort if private keys are being imported
         if (pwallet->IsWalletFlagSet(WALLET_FLAG_DISABLE_PRIVATE_KEYS) && !privkey_map.empty()) {
@@ -1132,7 +1230,7 @@ static UniValue ProcessImport(CWallet * const pwallet, const UniValue& data, con
         // Check whether we have any work to do
         for (const CScript& script : script_pub_keys) {
             if (::IsMine(*pwallet, script) & ISMINE_SPENDABLE) {
-                throw JSONRPCError(RPC_WALLET_ERROR, "The wallet already contains the private key for this address or script");
+                throw JSONRPCError(RPC_WALLET_ERROR, "The wallet already contains the private key for this address or script (\"" + HexStr(script.begin(), script.end()) + "\")");
             }
         }
 
@@ -1172,8 +1270,7 @@ static UniValue ProcessImport(CWallet * const pwallet, const UniValue& data, con
             }
             CTxDestination dest;
             ExtractDestination(script, dest);
-            if (!internal) {
-                assert(IsValidDestination(dest));
+            if (!internal && IsValidDestination(dest)) {
                 pwallet->SetAddressBook(dest, label, "receive");
             }
         }
@@ -1226,7 +1323,8 @@ UniValue importmulti(const JSONRPCRequest& mainRequest)
                         {
                             {"", RPCArg::Type::OBJ, /* opt */ false, /* default_val */ "", "",
                                 {
-                                    {"scriptPubKey", RPCArg::Type::STR, /* opt */ false, /* default_val */ "", "Type of scriptPubKey (string for script, json for address)",
+                                    {"desc", RPCArg::Type::STR, /* opt */ true, /* default_val */ "", "Descriptor to import. If using descriptor, do not also provide address/scriptPubKey, scripts, or pubkeys"},
+                                    {"scriptPubKey", RPCArg::Type::STR, /* opt */ false, /* default_val */ "", "Type of scriptPubKey (string for script, json for address). Should not be provided if using a descriptor",
                                         /* oneline_description */ "", {"\"<script>\" | { \"address\":\"<address>\" }", "string / json"}
                                     },
                                     {"timestamp", RPCArg::Type::NUM, /* opt */ false, /* default_val */ "", "Creation time of the key in seconds since epoch (Jan 1 1970 GMT),\n"
@@ -1249,6 +1347,12 @@ UniValue importmulti(const JSONRPCRequest& mainRequest)
                                             {"key", RPCArg::Type::STR, /* opt */ false, /* default_val */ "", ""},
                                         }
                                     },
+                                    {"range", RPCArg::Type::OBJ, /* opt */ true, /* default_val */ "", "If a ranged descriptor is used, this specifies the start and end of the range to import",
+                                        {
+                                            {"start", RPCArg::Type::NUM, /* opt */ true, /* default_val */ "0", "Start of the range to import"},
+                                            {"end", RPCArg::Type::NUM, /* opt */ false, /* default_val */ "", "End of the range to import (inclusive)"},
+                                        }
+                                    },
                                     {"internal", RPCArg::Type::BOOL, /* opt */ true, /* default_val */ "false", "Stating whether matching outputs should be treated as not incoming payments (also known as change)"},
                                     {"watchonly", RPCArg::Type::BOOL, /* opt */ true, /* default_val */ "false", "Stating whether matching outputs should be considered watchonly."},
                                     {"label", RPCArg::Type::STR, /* opt */ true, /* default_val */ "''", "Label to assign to the address, only allowed with internal=false"},