Merge bitcoin/bitcoin#21283: Implement BIP 370 PSBTv2

9fa4076b20 test: Test merging implicit PSBTv0 with explicit PSBTv0 (w0xlt)
1660c18232 doc: Release notes for psbtv2 (Ava Chow)
470e52a5f8 fuzz: Enforce additional version invariants in PSBT fuzzer (Antoine Poinsot)
5bd0579c09 test: Tests for PSBT AddInput and AddOutput (Ava Chow)
b8b6e7f0c2 tests: Add PSBT unit test for ComputeTimeLock (Ava Chow)
0bc1c2e508 tests: Add test vectors from BIP 370 (Ava Chow)
e0e4dbdeb5 psbt: Change default psbt version to 2 (Ava Chow)
bcc1dca77b Add psbt_version to PSBT RPCs and default to v2 (Ava Chow)
ab38c30195 Implement PSBTv2 field merging (Ava Chow)
93e339e29f Implement PSBTv2 AddInput and AddOutput (Ava Chow)
b39c86ae60 Allow specifying PSBT version in constructor (Ava Chow)
dcc9a3c8df Implement PSBTv2 in decodepsbt (Ava Chow)
5770dbd39f Add PSBT::ComputeLockTime() (Ava Chow)
863cf47b33 Update test_framework/psbt.py for PSBTv2 (Ava Chow)
925161eaf0 Implement PSBTv2 fields de/ser (Ava Chow)
d9cf658ee0 Restrict joinpsbts to PSBTv0 only (Ava Chow)
3da0e16012 Replace PSBT.tx with PSBT::GetUnsignedTx and PSBT::GetUniqueID (Ava Chow)
c568624ff2 psbt: Return std::optional from PrecomputePSBTData (Ava Chow)
092de4f1f6 Replace PSBT::GetInputUTXO with PSBTInput::GetUTXO (Ava Chow)
82c9fe3179 psbt: Use PSBTInput and PSBTOutput fields instead of accessing global tx (Ava Chow)
95897507e9 psbt: AddInput and AddOutput should take only PSBTInput and PSBTOutput (Ava Chow)
1b7d323a72 Add PSBTInput::GetOutPoint (Ava Chow)
543d3e1cdc psbt: add PSBTv2 global tx fields (Ava Chow)
c01c7f068c psbt: Remove default constructor (Ava Chow)
9671aa08c2 psbt: add tx input and output fields in PSBTInput and PSBTOutput (Ava Chow)
990b084f11 Have PSBTInput and PSBTOutput know the PSBT's version (Ava Chow)
7eacc21ff6 psbt: make PSBT structs into classes (Ava Chow)
f926c326bb gui: Store PSBT in std::optional in PSBTOperationsDialog (Ava Chow)
1e2d146b47 psbt: Refactor duplicate key lookup and size checks (Ava Chow)
88384180d3 test: PSBTs should roundtrip through RPCs that do nothing (Ava Chow)
001877500d test: construct psbt with unknown field programmatically (David Gumberg)
0cb884e6df psbt: Fill hash preimages and taproot builder from SignatureData (Ava Chow)

Pull request description:

  BIP 370 PSBTv2 introduces several new fields and different invariants for PSBT. This PR implements those new fields and restructures the PSBT implementation to match PSBTv2 but still remain compatible with PSBTv0.

ACKs for top commit:
  nervana21:
    re-ACK 9fa4076b20
  theStack:
    re-ACK 9fa4076b20
  w0xlt:
    ACK 9fa4076b20

Tree-SHA512: ab0a5ada4fa5fca27ba9ec9c291a44b30e69d6db11971957572d86c58c71c4caa4557dc25f403e1170ba4fac751306d074cc582defefc6e2fdd37be51c3d9dd0

test/functional/test_framework/psbt.py

@@ -4,11 +4,15 @@
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 import base64
+import struct
+
+from io import BytesIO
 
 from .util import assert_equal
 from .messages import (
     CTransaction,
     deser_string,
+    deser_compact_size,
     from_binary,
     ser_compact_size,
 )
@@ -108,37 +112,81 @@ class PSBT:
         self.g = g if g is not None else PSBTMap()
         self.i = i if i is not None else []
         self.o = o if o is not None else []
-        self.tx = None
+        self.version = None
 
     def deserialize(self, f):
         assert_equal(f.read(5), b"psbt\xff")
         self.g = from_binary(PSBTMap, f)
-        assert PSBT_GLOBAL_UNSIGNED_TX in self.g.map
-        self.tx = from_binary(CTransaction, self.g.map[PSBT_GLOBAL_UNSIGNED_TX])
-        self.i = [from_binary(PSBTMap, f) for _ in self.tx.vin]
-        self.o = [from_binary(PSBTMap, f) for _ in self.tx.vout]
+
+        self.version = 0
+        if PSBT_GLOBAL_VERSION in self.g.map:
+            self.version = struct.unpack("<I", self.g.map[PSBT_GLOBAL_VERSION])[0]
+            assert self.version in [0, 2]
+        if self.version == 2:
+            assert PSBT_GLOBAL_INPUT_COUNT in self.g.map
+            assert PSBT_GLOBAL_OUTPUT_COUNT in self.g.map
+            in_count = deser_compact_size(BytesIO(self.g.map[PSBT_GLOBAL_INPUT_COUNT]))
+            out_count = deser_compact_size(BytesIO(self.g.map[PSBT_GLOBAL_OUTPUT_COUNT]))
+        else:
+            assert PSBT_GLOBAL_UNSIGNED_TX in self.g.map
+            tx = from_binary(CTransaction, self.g.map[PSBT_GLOBAL_UNSIGNED_TX])
+            in_count = len(tx.vin)
+            out_count = len(tx.vout)
+
+        self.i = [from_binary(PSBTMap, f) for _ in range(in_count)]
+        self.o = [from_binary(PSBTMap, f) for _ in range(out_count)]
         return self
 
     def serialize(self):
         assert isinstance(self.g, PSBTMap)
         assert isinstance(self.i, list) and all(isinstance(x, PSBTMap) for x in self.i)
         assert isinstance(self.o, list) and all(isinstance(x, PSBTMap) for x in self.o)
-        assert PSBT_GLOBAL_UNSIGNED_TX in self.g.map
-        tx = from_binary(CTransaction, self.g.map[PSBT_GLOBAL_UNSIGNED_TX])
-        assert_equal(len(tx.vin), len(self.i))
-        assert_equal(len(tx.vout), len(self.o))
+        if self.version is not None and self.version == 2:
+            self.g.map[PSBT_GLOBAL_INPUT_COUNT] = ser_compact_size(len(self.i))
+            self.g.map[PSBT_GLOBAL_OUTPUT_COUNT] = ser_compact_size(len(self.o))
+        if self.version is None or (self.version is not None and self.version == 0):
+            assert PSBT_GLOBAL_UNSIGNED_TX in self.g.map
+            tx = from_binary(CTransaction, self.g.map[PSBT_GLOBAL_UNSIGNED_TX])
+            assert_equal(len(tx.vin), len(self.i))
+            assert_equal(len(tx.vout), len(self.o))
 
         psbt = [x.serialize() for x in [self.g] + self.i + self.o]
         return b"psbt\xff" + b"".join(psbt)
 
     def make_blank(self):
         """
-        Remove all fields except for PSBT_GLOBAL_UNSIGNED_TX
+        Remove all fields except for required fields depending on version
         """
-        for m in self.i + self.o:
-            m.map.clear()
+        if self.version == 0:
+            for m in self.i + self.o:
+                m.map.clear()
 
-        self.g = PSBTMap(map={PSBT_GLOBAL_UNSIGNED_TX: self.g.map[PSBT_GLOBAL_UNSIGNED_TX]})
+            self.g = PSBTMap(map={PSBT_GLOBAL_UNSIGNED_TX: self.g.map[PSBT_GLOBAL_UNSIGNED_TX]})
+        elif self.version == 2:
+            self.g = PSBTMap(map={
+                PSBT_GLOBAL_TX_VERSION: self.g.map[PSBT_GLOBAL_TX_VERSION],
+                PSBT_GLOBAL_INPUT_COUNT: self.g.map[PSBT_GLOBAL_INPUT_COUNT],
+                PSBT_GLOBAL_OUTPUT_COUNT: self.g.map[PSBT_GLOBAL_OUTPUT_COUNT],
+                PSBT_GLOBAL_VERSION: self.g.map[PSBT_GLOBAL_VERSION],
+            })
+
+            new_i = []
+            for m in self.i:
+                new_i.append(PSBTMap(map={
+                    PSBT_IN_PREVIOUS_TXID: m.map[PSBT_IN_PREVIOUS_TXID],
+                    PSBT_IN_OUTPUT_INDEX: m.map[PSBT_IN_OUTPUT_INDEX],
+                }))
+            self.i = new_i
+
+            new_o = []
+            for m in self.o:
+                new_o.append(PSBTMap(map={
+                    PSBT_OUT_SCRIPT: m.map[PSBT_OUT_SCRIPT],
+                    PSBT_OUT_AMOUNT: m.map[PSBT_OUT_AMOUNT],
+                }))
+            self.o = new_o
+        else:
+            assert False
 
     def to_base64(self):
         return base64.b64encode(self.serialize()).decode("utf8")