Merge e1d6179b61 into c5e44a0435

src/core_write.cpp

@@ -153,7 +153,9 @@ void ScriptToUniv(const CScript& script, UniValue& out, bool include_hex, bool i
 
     out.pushKV("asm", ScriptToAsmStr(script));
     if (include_address) {
-        out.pushKV("desc", InferDescriptor(script, provider ? *provider : DUMMY_SIGNING_PROVIDER)->ToString());
+        auto desc = InferDescriptor(script, provider ? *provider : DUMMY_SIGNING_PROVIDER);
+        // future: make 'InferDescriptor' return the error cause
+        if (desc) out.pushKV("desc", desc->ToString());
     }
     if (include_hex) {
         out.pushKV("hex", HexStr(script));

src/policy/policy.cpp

@@ -87,7 +87,7 @@ bool IsStandard(const CScript& scriptPubKey, const std::optional<unsigned>& max_
         unsigned char m = vSolutions.front()[0];
         unsigned char n = vSolutions.back()[0];
         // Support up to x-of-3 multisig txns as standard
-        if (n < 1 || n > 3)
+        if (n < 1 || n > MAX_BARE_MULTISIG_PUBKEYS_NUM)
             return false;
         if (m < 1 || m > n)
             return false;

src/policy/policy.h

@@ -44,6 +44,8 @@ static constexpr unsigned int DEFAULT_INCREMENTAL_RELAY_FEE{1000};
 static constexpr unsigned int DEFAULT_BYTES_PER_SIGOP{20};
 /** Default for -permitbaremultisig */
 static constexpr bool DEFAULT_PERMIT_BAREMULTISIG{true};
+/** The maximum number of pubkeys in a bare multisig output script */
+static constexpr unsigned int MAX_BARE_MULTISIG_PUBKEYS_NUM{3};
 /** The maximum number of witness stack items in a standard P2WSH script */
 static constexpr unsigned int MAX_STANDARD_P2WSH_STACK_ITEMS{100};
 /** The maximum size in bytes of each witness stack item in a standard P2WSH script */

src/rpc/blockchain.cpp

@@ -1124,7 +1124,7 @@ static RPCHelpMan gettxout()
                 {RPCResult::Type::STR_AMOUNT, "value", "The transaction value in " + CURRENCY_UNIT},
                 {RPCResult::Type::OBJ, "scriptPubKey", "", {
                     {RPCResult::Type::STR, "asm", "Disassembly of the output script"},
-                    {RPCResult::Type::STR, "desc", "Inferred descriptor for the output"},
+                    {RPCResult::Type::STR, "desc", /*optional=*/true, "Inferred top level descriptor for the script (if any)"},
                     {RPCResult::Type::STR_HEX, "hex", "The raw output script bytes, hex-encoded"},
                     {RPCResult::Type::STR, "type", "The type, eg pubkeyhash"},
                     {RPCResult::Type::STR, "address", /*optional=*/true, "The Bitcoin address (only if a well-defined address exists)"},
@@ -2316,9 +2316,10 @@ static RPCHelpMan scantxoutset()
             FlatSigningProvider provider;
             auto scripts = EvalDescriptorStringOrObject(scanobject, provider);
             for (CScript& script : scripts) {
-                std::string inferred = InferDescriptor(script, provider)->ToString();
+                auto desc = InferDescriptor(script, provider);
+                if (!desc) throw JSONRPCError(RPC_INVALID_PARAMETER, strprintf("Invalid descriptor found: '%s'", scanobject.get_str()));
                 needles.emplace(script);
-                descriptors.emplace(std::move(script), std::move(inferred));
+                descriptors.emplace(std::move(script), desc->ToString());
             }
         }
 

src/rpc/output_script.cpp

@@ -146,6 +146,7 @@ static RPCHelpMan createmultisig()
 
             // Make the descriptor
             std::unique_ptr<Descriptor> descriptor = InferDescriptor(GetScriptForDestination(dest), keystore);
+            if (!descriptor) throw JSONRPCError(RPC_INTERNAL_ERROR, "Invalid descriptor generated");
 
             UniValue result(UniValue::VOBJ);
             result.pushKV("address", EncodeDestination(dest));

src/rpc/rawtransaction.cpp

@@ -493,7 +493,7 @@ static RPCHelpMan decodescript()
             RPCResult::Type::OBJ, "", "",
             {
                 {RPCResult::Type::STR, "asm", "Disassembly of the script"},
-                {RPCResult::Type::STR, "desc", "Inferred descriptor for the script"},
+                {RPCResult::Type::STR, "desc", /*optional=*/true, "Inferred top level descriptor for the script (if any)"},
                 {RPCResult::Type::STR, "type", "The output type (e.g. " + GetAllOutputTypes() + ")"},
                 {RPCResult::Type::STR, "address", /*optional=*/true, "The Bitcoin address (only if a well-defined address exists)"},
                 {RPCResult::Type::STR, "p2sh", /*optional=*/true,
@@ -505,7 +505,7 @@ static RPCHelpMan decodescript()
                      {RPCResult::Type::STR_HEX, "hex", "The raw output script bytes, hex-encoded"},
                      {RPCResult::Type::STR, "type", "The type of the output script (e.g. witness_v0_keyhash or witness_v0_scripthash)"},
                      {RPCResult::Type::STR, "address", /*optional=*/true, "The Bitcoin address (only if a well-defined address exists)"},
-                     {RPCResult::Type::STR, "desc", "Inferred descriptor for the script"},
+                     {RPCResult::Type::STR, "desc", /*optional=*/true, "Inferred descriptor for the script (if any)"},
                      {RPCResult::Type::STR, "p2sh-segwit", "address of the P2SH script wrapping this witness redeem script"},
                  }},
             },
@@ -529,9 +529,14 @@ static RPCHelpMan decodescript()
     std::vector<std::vector<unsigned char>> solutions_data;
     const TxoutType which_type{Solver(script, solutions_data)};
 
+    bool can_wrap_p2sh = true;
     const bool can_wrap{[&] {
         switch (which_type) {
-        case TxoutType::MULTISIG:
+        case TxoutType::MULTISIG: {
+            // Verify it doesn't exceed p2sh consensus limits
+            can_wrap_p2sh = script.size() <= MAX_SCRIPT_ELEMENT_SIZE;
+            break;
+        }
         case TxoutType::NONSTANDARD:
         case TxoutType::PUBKEY:
         case TxoutType::PUBKEYHASH:
@@ -561,7 +566,7 @@ static RPCHelpMan decodescript()
     }()};
 
     if (can_wrap) {
-        r.pushKV("p2sh", EncodeDestination(ScriptHash(script)));
+        if (can_wrap_p2sh) r.pushKV("p2sh", EncodeDestination(ScriptHash(script)));
         // P2SH and witness programs cannot be wrapped in P2WSH, if this script
         // is a witness program, don't return addresses for a segwit programs.
         const bool can_wrap_P2WSH{[&] {
@@ -822,7 +827,7 @@ const RPCResult decodepsbt_inputs{
                 {RPCResult::Type::OBJ, "scriptPubKey", "",
                 {
                     {RPCResult::Type::STR, "asm", "Disassembly of the output script"},
-                    {RPCResult::Type::STR, "desc", "Inferred descriptor for the output"},
+                    {RPCResult::Type::STR, "desc", /*optional=*/true, "Inferred top level descriptor for the script (if any)"},
                     {RPCResult::Type::STR_HEX, "hex", "The raw output script bytes, hex-encoded"},
                     {RPCResult::Type::STR, "type", "The type, eg 'pubkeyhash'"},
                     {RPCResult::Type::STR, "address", /*optional=*/true, "The Bitcoin address (only if a well-defined address exists)"},

src/script/descriptor.cpp

@@ -1857,8 +1857,8 @@ std::vector<std::unique_ptr<DescriptorImpl>> ParseScript(uint32_t& key_exp_index
             return {};
         }
         if (ctx == ParseScriptContext::TOP) {
-            if (providers.size() > 3) {
+            if (providers.size() > MAX_BARE_MULTISIG_PUBKEYS_NUM) {
-                error = strprintf("Cannot have %u pubkeys in bare multisig; only at most 3 pubkeys", providers.size());
+                error = strprintf("Cannot have %u pubkeys in bare multisig; only at most %u pubkeys", providers.size(), MAX_BARE_MULTISIG_PUBKEYS_NUM);
                 return {};
             }
         }
@@ -2244,6 +2244,17 @@ std::unique_ptr<DescriptorImpl> InferScript(const CScript& script, ParseScriptCo
                 break;
             }
         }
+
+        // Check bare multisig pubkeys number limit
+        if (ctx == ParseScriptContext::TOP && providers.size() > MAX_BARE_MULTISIG_PUBKEYS_NUM) {
+            return nullptr;
+        }
+
+        // Verify we don't exceed consensus limits
+        if (ctx == ParseScriptContext::P2SH && script.size() > MAX_SCRIPT_ELEMENT_SIZE) {
+            return nullptr;
+        }
+
         if (ok) return std::make_unique<MultisigDescriptor>((int)data[0][0], std::move(providers));
     }
     if (txntype == TxoutType::SCRIPTHASH && ctx == ParseScriptContext::TOP) {

src/wallet/rpc/addresses.cpp

@@ -292,6 +292,13 @@ RPCHelpMan addmultisigaddress()
     CScript inner;
     CTxDestination dest = AddAndGetMultisigDestination(required, pubkeys, output_type, provider, inner);
 
+    // Before importing the scripts into the wallet, check we can make a descriptor out of it.
+    std::unique_ptr<Descriptor> descriptor = InferDescriptor(GetScriptForDestination(dest), spk_man);
+    if (!descriptor) {
+        // Shouldn't happen; we crafted the destination internally.
+        throw JSONRPCError(RPC_INTERNAL_ERROR, "Invalid descriptor generated");
+    }
+
     // Import scripts into the wallet
     for (const auto& [id, script] : provider.scripts) {
         // Due to a bug in the legacy wallet, the p2sh maximum script size limit is also imposed on 'p2sh-segwit' and 'bech32' redeem scripts.
@@ -313,9 +320,6 @@ RPCHelpMan addmultisigaddress()
     // Store destination in the addressbook
     pwallet->SetAddressBook(dest, label, AddressPurpose::SEND);
 
-    // Make the descriptor
-    std::unique_ptr<Descriptor> descriptor = InferDescriptor(GetScriptForDestination(dest), spk_man);
-
     UniValue result(UniValue::VOBJ);
     result.pushKV("address", EncodeDestination(dest));
     result.pushKV("redeemScript", HexStr(inner));

test/functional/rpc_decodescript.py

@@ -96,6 +96,16 @@ class DecodeScriptTest(BitcoinTestFramework):
         assert_equal('witness_v0_scripthash', rpc_result['segwit']['type'])
         assert_equal('0 ' + multisig_script_hash, rpc_result['segwit']['asm'])
 
+        # Check decoding a multisig redeem script doesn't return an invalid descriptor
+        self.log.info("- multisig invalid")
+        # Decode a +520 bytes consensus-invalid p2sh multisig - provided script translates to multi(20, keys)
+        large_multisig_script = '0114' + push_public_key * 20 + '0114' + 'ae'
+        rpc_result = self.nodes[0].decodescript(large_multisig_script)
+        # Verify it is valid only under segwit rules, not for bare multisig nor p2sh.
+        assert 'desc' not in rpc_result
+        assert 'p2sh' not in rpc_result
+        assert 'segwit' in rpc_result
+
         self.log.info ("- P2SH")
         # OP_HASH160 <Hash160(redeemScript)> OP_EQUAL.
         # push_public_key_hash here should actually be the hash of a redeem script.