Merge bitcoin/bitcoin#24148: Miniscript support in Output Descriptors

ffc79b8e49 qa: functional test Miniscript watchonly support (Antoine Poinsot)
bfb036756a Miniscript support in output descriptors (Antoine Poinsot)
4a082887be qa: better error reporting on descriptor parsing error (Antoine Poinsot)
d25d58bf5f miniscript: add a helper to find the first insane sub with no child (Antoine Poinsot)
c38c7c5817 miniscript: don't check for top level validity at parsing time (Antoine Poinsot)

Pull request description:

  This adds Miniscript support for Output Descriptors without any signing logic (yet). See the OP of #24147 for a description of Miniscript and a rationale of having it in Bitcoin Core.
  On its own, this PR adds "watchonly" support for Miniscript descriptors in the descriptor wallet. A follow-up adds signing support.

  A minified corpus of Miniscript Descriptors for the `descriptor_parse` fuzz target is available at https://github.com/bitcoin-core/qa-assets/pull/92.
  The Miniscript descriptors used in the unit tests here and in #24149 were cross-tested against the Rust implementation at https://github.com/rust-bitcoin/rust-miniscript.

  This PR contains code and insights from Pieter Wuille.

ACKs for top commit:
  Sjors:
    re-utACK ffc79b8e49
  achow101:
    ACK ffc79b8e49
  w0xlt:
    reACK ffc79b8e49

Tree-SHA512: 02d919d38bb626d3c557eca3680ce71117739fa161b7a92cfdb6c9c432ed88870b1ed127ba24248574c40c7428217d7e9bdd986fd8cd7c51fae8c776e1271fb9

test/functional/test_runner.py

@@ -205,6 +205,7 @@ BASE_SCRIPTS = [
     'wallet_keypool.py --legacy-wallet',
     'wallet_keypool.py --descriptors',
     'wallet_descriptor.py --descriptors',
+    'wallet_miniscript.py',
     'feature_maxtipage.py',
     'p2p_nobloomfilter_messages.py',
     'p2p_filter.py',

test/functional/wallet_miniscript.py

@@ -0,0 +1,93 @@
+#!/usr/bin/env python3
+# Copyright (c) 2022 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 Miniscript descriptors integration in the wallet."""
+
+from test_framework.descriptors import descsum_create
+from test_framework.test_framework import BitcoinTestFramework
+from test_framework.util import assert_equal
+
+
+MINISCRIPTS = [
+    # One of two keys
+    "or_b(pk(tpubD6NzVbkrYhZ4XRMcMFMMFvzVt6jaDAtjZhD7JLwdPdMm9xa76DnxYYP7w9TZGJDVFkek3ArwVsuacheqqPog8TH5iBCX1wuig8PLXim4n9a/*),s:pk(tpubD6NzVbkrYhZ4WsqRzDmkL82SWcu42JzUvKWzrJHQ8EC2vEHRHkXj1De93sD3biLrKd8XGnamXURGjMbYavbszVDXpjXV2cGUERucLJkE6cy/*))",
+    # A script similar (same spending policy) to BOLT3's offered HTLC (with anchor outputs)
+    "or_d(pk(tpubD6NzVbkrYhZ4XRMcMFMMFvzVt6jaDAtjZhD7JLwdPdMm9xa76DnxYYP7w9TZGJDVFkek3ArwVsuacheqqPog8TH5iBCX1wuig8PLXim4n9a/*),and_v(and_v(v:pk(tpubD6NzVbkrYhZ4WsqRzDmkL82SWcu42JzUvKWzrJHQ8EC2vEHRHkXj1De93sD3biLrKd8XGnamXURGjMbYavbszVDXpjXV2cGUERucLJkE6cy/*),or_c(pk(tpubD6NzVbkrYhZ4YNwtTWrKRJQzQX3PjPKeUQg1gYh1hiLMkk1cw8SRLgB1yb7JzE8bHKNt6EcZXkJ6AqpCZL1aaRSjnG36mLgbQvJZBNsjWnG/*),v:hash160(7f999c905d5e35cefd0a37673f746eb13fba3640))),older(1)))",
+    # A Revault Unvault policy with the older() replaced by an after()
+    "andor(multi(2,tpubD6NzVbkrYhZ4YMQC15JS7QcrsAyfGrGiykweqMmPxTkEVScu7vCZLNpPXW1XphHwzsgmqdHWDQAfucbM72EEB1ZEyfgZxYvkZjYVXx1xS9p/*,tpubD6NzVbkrYhZ4WkCyc7E3z6g6NkypHMiecnwc4DpWHTPqFdteRGkEKukdrSSyJGNnGrHNMfy4BCw2UXo5soYRCtCDDfy4q8pc8oyB7RgTFv8/*),and_v(v:multi(4,030f64b922aee2fd597f104bc6cb3b670f1ca2c6c49b1071a1a6c010575d94fe5a,02abe475b199ec3d62fa576faee16a334fdb86ffb26dce75becebaaedf328ac3fe,0314f3dc33595b0d016bb522f6fe3a67680723d842c1b9b8ae6b59fdd8ab5cccb4,025eba3305bd3c829e4e1551aac7358e4178832c739e4fc4729effe428de0398ab),after(424242)),thresh(4,pkh(tpubD6NzVbkrYhZ4YVrNggiT2ptVHwnFbLBqDkCtV5HkxR4WtcRLAQReKTkqZGNcV6GE7cQsmpBzzSzhk16DUwB1gn1L7ZPnJF2dnNePP1uMBCY/*),a:pkh(tpubD6NzVbkrYhZ4YU9vM1s53UhD75UyJatx8EMzMZ3VUjR2FciNfLLkAw6a4pWACChzobTseNqdWk4G7ZdBqRDLtLSACKykTScmqibb1ZrCvJu/*),a:pkh(tpubD6NzVbkrYhZ4YUHcFfuH9iEBLiH8CBRJTpS7X3qjHmh82m1KCNbzs6w9gyK8oWHSZmKHWcakAXCGfbKg6xoCvKzQCWAHyxaC7QcWfmzyBf4/*),a:pkh(tpubD6NzVbkrYhZ4XXEmQtS3sgxpJbMyMg4McqRR1Af6ULzyrTRnhwjyr1etPD7svap9oFtJf4MM72brUb5o7uvF2Jyszc5c1t836fJW7SX2e8D/*)))",
+    # Liquid-like federated pegin with emergency recovery keys
+    "or_i(and_b(pk(029ffbe722b147f3035c87cb1c60b9a5947dd49c774cc31e94773478711a929ac0),a:and_b(pk(025f05815e3a1a8a83bfbb03ce016c9a2ee31066b98f567f6227df1d76ec4bd143),a:and_b(pk(025625f41e4a065efc06d5019cbbd56fe8c07595af1231e7cbc03fafb87ebb71ec),a:and_b(pk(02a27c8b850a00f67da3499b60562673dcf5fdfb82b7e17652a7ac54416812aefd),s:pk(03e618ec5f384d6e19ca9ebdb8e2119e5bef978285076828ce054e55c4daf473e2))))),and_v(v:thresh(2,pkh(tpubD6NzVbkrYhZ4YK67cd5fDe4fBVmGB2waTDrAt1q4ey9HPq9veHjWkw3VpbaCHCcWozjkhgAkWpFrxuPMUrmXVrLHMfEJ9auoZA6AS1g3grC/*),a:pkh(033841045a531e1adf9910a6ec279589a90b3b8a904ee64ffd692bd08a8996c1aa),a:pkh(02aebf2d10b040eb936a6f02f44ee82f8b34f5c1ccb20ff3949c2b28206b7c1068)),older(4209713)))",
+]
+
+
+class WalletMiniscriptTest(BitcoinTestFramework):
+    def set_test_params(self):
+        self.num_nodes = 1
+
+    def skip_test_if_missing_module(self):
+        self.skip_if_no_wallet()
+        self.skip_if_no_sqlite()
+
+    def watchonly_test(self, ms):
+        self.log.info(f"Importing Miniscript '{ms}'")
+        desc = descsum_create(f"wsh({ms})")
+        assert self.ms_wo_wallet.importdescriptors(
+            [
+                {
+                    "desc": desc,
+                    "active": True,
+                    "range": 2,
+                    "next_index": 0,
+                    "timestamp": "now",
+                }
+            ]
+        )[0]["success"]
+
+        self.log.info("Testing we derive new addresses for it")
+        assert_equal(
+            self.ms_wo_wallet.getnewaddress(), self.funder.deriveaddresses(desc, 0)[0]
+        )
+        assert_equal(
+            self.ms_wo_wallet.getnewaddress(), self.funder.deriveaddresses(desc, 1)[1]
+        )
+
+        self.log.info("Testing we detect funds sent to one of them")
+        addr = self.ms_wo_wallet.getnewaddress()
+        txid = self.funder.sendtoaddress(addr, 0.01)
+        self.wait_until(
+            lambda: len(self.ms_wo_wallet.listunspent(minconf=0, addresses=[addr])) == 1
+        )
+        utxo = self.ms_wo_wallet.listunspent(minconf=0, addresses=[addr])[0]
+        assert utxo["txid"] == txid and not utxo["solvable"]  # No satisfaction logic (yet)
+
+    def run_test(self):
+        self.log.info("Making a descriptor wallet")
+        self.funder = self.nodes[0].get_wallet_rpc(self.default_wallet_name)
+        self.nodes[0].createwallet(
+            wallet_name="ms_wo", descriptors=True, disable_private_keys=True
+        )
+        self.ms_wo_wallet = self.nodes[0].get_wallet_rpc("ms_wo")
+
+        # Sanity check we wouldn't let an insane Miniscript descriptor in
+        res = self.ms_wo_wallet.importdescriptors(
+            [
+                {
+                    "desc": descsum_create(
+                        "wsh(and_b(ripemd160(1fd9b55a054a2b3f658d97e6b84cf3ee00be429a),a:1))"
+                    ),
+                    "active": False,
+                    "timestamp": "now",
+                }
+            ]
+        )[0]
+        assert not res["success"]
+        assert "is not sane: witnesses without signature exist" in res["error"]["message"]
+
+        # Test we can track any type of Miniscript
+        for ms in MINISCRIPTS:
+            self.watchonly_test(ms)
+
+
+if __name__ == "__main__":
+    WalletMiniscriptTest().main()