Merge bitcoin/bitcoin#27113: rpc: Use a FlatSigningProvider in decodescript to allow inferring descriptors for scripts larger than 520 bytes

73ec4b2 tests: decodescript can infer descriptors for scripts >520 bytes (Andrew Chow)
7cc7822 rpc: Use FlatSigningProvider in decodescript (Andrew Chow)

Pull request description:

  `FillableSigningProvider` limits scripts to 520 bytes even though segwit allows scripts to be larger than that. We can avoid this limit by using a `FlatSigningProvider` so that such larger scripts can be decoded.

  Fixes #27111

ACKs for top commit:
  instagibbs:
    ACK bitcoin/bitcoin@73ec4b2

Tree-SHA512: c0e6d21025e2da864471989ac94c54e127d05459b9b048f34a0da8d76d8e372d5472a2e667ba2db74d6286e3e6faa55486ffa9232a068b519afa676394031d5a

Author: fanquake

src/rpc/rawtransaction.cpp

@@ -522,14 +522,14 @@ static RPCHelpMan decodescript()
         if (can_wrap_P2WSH) {
             UniValue sr(UniValue::VOBJ);
             CScript segwitScr;
-            FillableSigningProvider provider;
+            FlatSigningProvider provider;
             if (which_type == TxoutType::PUBKEY) {
                 segwitScr = GetScriptForDestination(WitnessV0KeyHash(Hash160(solutions_data[0])));
             } else if (which_type == TxoutType::PUBKEYHASH) {
                 segwitScr = GetScriptForDestination(WitnessV0KeyHash(uint160{solutions_data[0]}));
             } else {
                 // Scripts that are not fit for P2WPKH are encoded as P2WSH.
-                provider.AddCScript(script);
+                provider.scripts[CScriptID(script)] = script;
                 segwitScr = GetScriptForDestination(WitnessV0ScriptHash(script));
             }
             ScriptToUniv(segwitScr, /*out=*/sr, /*include_hex=*/true, /*include_address=*/true, /*provider=*/&provider);

test/functional/rpc_decodescript.py

@@ -272,6 +272,9 @@ def decodescript_miniscript(self):
         # Miniscript-incompatible offered HTLC
         res = self.nodes[0].decodescript("82012088a914ffffffffffffffffffffffffffffffffffffffff882102ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffacb2")
         assert res["segwit"]["desc"] == "wsh(raw(82012088a914ffffffffffffffffffffffffffffffffffffffff882102ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffacb2))#ra6w2xa7"
+        # Miniscript-compatible multisig bigger than 520 byte P2SH limit.
+        res = self.nodes[0].decodescript("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")
+        assert_equal(res["segwit"]["desc"], "wsh(or_d(multi(11,020e0338c96a8870479f2396c373cc7696ba124e8635d41b0ea581112b67817261,02675333a4e4b8fb51d9d4e22fa5a8eaced3fdac8a8cbf9be8c030f75712e6af99,02896807d54bc55c24981f24a453c60ad3e8993d693732288068a23df3d9f50d48,029e51a5ef5db3137051de8323b001749932f2ff0d34c82e96a2c2461de96ae56c,02a4e1a9638d46923272c266631d94d36bdb03a64ee0e14c7518e49d2f29bc4010,031c41fdbcebe17bec8d49816e00ca1b5ac34766b91c9f2ac37d39c63e5e008afb,03079e252e85abffd3c401a69b087e590a9b86f33f574f08129ccbd3521ecf516b,03111cf405b627e22135b3b3733a4a34aa5723fb0f58379a16d32861bf576b0ec2,0318f331b3e5d38156da6633b31929c5b220349859cc9ca3d33fb4e68aa0840174,03230dae6b4ac93480aeab26d000841298e3b8f6157028e47b0897c1e025165de1,035abff4281ff00660f99ab27bb53e6b33689c2cd8dcd364bc3c90ca5aea0d71a6,03bd45cddfacf2083b14310ae4a84e25de61e451637346325222747b157446614c,03cc297026b06c71cbfa52089149157b5ff23de027ac5ab781800a578192d17546,03d3bde5d63bdb3a6379b461be64dad45eabff42f758543a9645afd42f6d424828,03ed1e8d5109c9ed66f7941bc53cc71137baa76d50d274bda8d5e8ffbd6e61fe9a),and_v(v:older(4032),multi(2,03aab896d53a8e7d6433137bbba940f9c521e085dd07e60994579b64a6d992cf79,0291b7d0b1b692f8f524516ed950872e5da10fb1b808b5a526dedc6fed1cf29807,0386aa9372fbab374593466bc5451dc59954e90787f08060964d95c87ef34ca5bb))))#7jwwklk4")
 
     def run_test(self):
         self.log.info("Test decoding of standard input scripts [scriptSig]")