From 2fbb71f5c989e6548a0f2269b192fab39cf265f2 Mon Sep 17 00:00:00 2001
From: Thomas <t.rossi@merkur.io>
Date: Wed, 18 Nov 2020 21:30:13 +0100
Subject: [PATCH 1/2] flagbyte errors

---
 bitcoin/core/__init__.py           | 24 +++++++++++++++++++++---
 bitcoin/tests/data/tx_invalid.json |  7 +++++++
 bitcoin/tests/test_transactions.py |  2 +-
 3 files changed, 29 insertions(+), 4 deletions(-)

diff --git a/bitcoin/core/__init__.py b/bitcoin/core/__init__.py
index 272bec5c..9055a6e4 100644
--- a/bitcoin/core/__init__.py
+++ b/bitcoin/core/__init__.py
@@ -387,9 +387,9 @@ def from_txwitness(cls, txwitness):
 
 class CTransaction(ImmutableSerializable):
     """A transaction"""
-    __slots__ = ['nVersion', 'vin', 'vout', 'nLockTime', 'wit']
+    __slots__ = ['nVersion', 'vin', 'vout', 'nLockTime', 'wit', 'flagbyte']
 
-    def __init__(self, vin=(), vout=(), nLockTime=0, nVersion=1, witness=CTxWitness()):
+    def __init__(self, vin=(), vout=(), nLockTime=0, nVersion=1, witness=CTxWitness(), flagbyte=0):
         """Create a new transaction
 
         vin and vout are iterables of transaction inputs and outputs
@@ -403,6 +403,7 @@ def __init__(self, vin=(), vout=(), nLockTime=0, nVersion=1, witness=CTxWitness(
         object.__setattr__(self, 'vin', tuple(CTxIn.from_txin(txin) for txin in vin))
         object.__setattr__(self, 'vout', tuple(CTxOut.from_txout(txout) for txout in vout))
         object.__setattr__(self, 'wit', CTxWitness.from_txwitness(witness))
+        object.__setattr__(self, 'flagbyte', flagbyte)
 
     @classmethod
     def stream_deserialize(cls, f):
@@ -428,8 +429,19 @@ def stream_deserialize(cls, f):
             wit = CTxWitness(tuple(0 for dummy in range(len(vin))))
             wit = wit.stream_deserialize(f)
             nLockTime = struct.unpack(b"<I", ser_read(f,4))[0]
-            return cls(vin, vout, nLockTime, nVersion, wit)
+            return cls(vin, vout, nLockTime, nVersion, wit, flagbyte)
         else:
+            try:
+                vin = VectorSerializer.stream_deserialize(CTxIn, f)
+                if(len(vin)>0 and markerbyte ==0 and flagbyte!=1):
+                    vout = VectorSerializer.stream_deserialize(CTxOut, f)
+                    wit = CTxWitness(tuple(0 for dummy in range(len(vin))))
+                    wit = wit.stream_deserialize(f)
+                    nLockTime = struct.unpack(b"<I", ser_read(f,4))[0]
+                    return cls(vin, vout, nLockTime, nVersion, wit, flagbyte)
+            except:
+                #failing here can mean we just need to deserialize a normal tx after setting the cursor in the right position
+                pass
             f.seek(pos) # put marker byte back, since we don't have peek
             vin = VectorSerializer.stream_deserialize(CTxIn, f)
             vout = VectorSerializer.stream_deserialize(CTxOut, f)
@@ -825,6 +837,12 @@ def CheckTransaction(tx):
             if txin.prevout.is_null():
                 raise CheckTransactionError("CheckTransaction() : prevout is null")
 
+    # Check for flagbyte segwit related errors:
+    if(tx.flagbyte!=0 and tx.flagbyte!=1):
+        raise CheckTransactionError("CheckTransaction() : Unknown optional flag")
+
+    if(tx.flagbyte==1 and tx.wit.is_null()):
+        raise CheckTransactionError("CheckTransaction() : Superfluous witnes records")
 
 
 
diff --git a/bitcoin/tests/data/tx_invalid.json b/bitcoin/tests/data/tx_invalid.json
index 2bfe7c7e..27277537 100644
--- a/bitcoin/tests/data/tx_invalid.json
+++ b/bitcoin/tests/data/tx_invalid.json
@@ -71,5 +71,12 @@
 [[["ad503f72c18df5801ee64d76090afe4c607fb2b822e9b7b63c5826c50e22fc3b", 0, "0x21 0x027c3a97665bf283a102a587a62a30a0c102d4d3b141015e2cae6f64e2543113e5 CHECKSIG NOT"]],
 "01000000013bfc220ec526583cb6b7e922b8b27f604cfe0a09764de61e80f58dc1723f50ad0000000000ffffffff0101000000000000002321027c3a97665bf283a102a587a62a30a0c102d4d3b141015e2cae6f64e2543113e5ac00000000", true],
 
+["Witness with SigHash Single|AnyoneCanPay (same signature as previous)"],
+[[["0000000000000000000000000000000000000000000000000000000000000100", 0, "0x51", 1000],
+["0000000000000000000000000000000000000000000000000000000000000100", 1, "0x00 0x14 0x4c9c3dfac4207d5d8cb89df5722cb3d712385e3f", 2000],
+["0000000000000000000000000000000000000000000000000000000000000100", 2, "0x51", 3000]],
+"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", "P2SH,WITNESS"],
+
+
 ["Make diffs cleaner by leaving a comment here without comma at the end"]
 ]
diff --git a/bitcoin/tests/test_transactions.py b/bitcoin/tests/test_transactions.py
index f96c5b32..6748dfa8 100644
--- a/bitcoin/tests/test_transactions.py
+++ b/bitcoin/tests/test_transactions.py
@@ -30,7 +30,7 @@ def load_test_vectors(name):
 
             prevouts = {}
             for json_prevout in test_case[0]:
-                assert len(json_prevout) == 3
+                assert len(json_prevout) >= 3
                 n = json_prevout[1]
                 if n == -1:
                     n = 0xffffffff

From 7b1061fc40edcf47b8948113cbe98648cbed5ebd Mon Sep 17 00:00:00 2001
From: Thomas <t.rossi@merkur.io>
Date: Wed, 18 Nov 2020 22:00:33 +0100
Subject: [PATCH 2/2] flagbyte errors, test data description

---
 bitcoin/tests/data/tx_invalid.json | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/bitcoin/tests/data/tx_invalid.json b/bitcoin/tests/data/tx_invalid.json
index 27277537..46e2e8d5 100644
--- a/bitcoin/tests/data/tx_invalid.json
+++ b/bitcoin/tests/data/tx_invalid.json
@@ -71,7 +71,7 @@
 [[["ad503f72c18df5801ee64d76090afe4c607fb2b822e9b7b63c5826c50e22fc3b", 0, "0x21 0x027c3a97665bf283a102a587a62a30a0c102d4d3b141015e2cae6f64e2543113e5 CHECKSIG NOT"]],
 "01000000013bfc220ec526583cb6b7e922b8b27f604cfe0a09764de61e80f58dc1723f50ad0000000000ffffffff0101000000000000002321027c3a97665bf283a102a587a62a30a0c102d4d3b141015e2cae6f64e2543113e5ac00000000", true],
 
-["Witness with SigHash Single|AnyoneCanPay (same signature as previous)"],
+["Witness with SigHash Single|AnyoneCanPay (same signature as previous), flagbyte set to 02"],
 [[["0000000000000000000000000000000000000000000000000000000000000100", 0, "0x51", 1000],
 ["0000000000000000000000000000000000000000000000000000000000000100", 1, "0x00 0x14 0x4c9c3dfac4207d5d8cb89df5722cb3d712385e3f", 2000],
 ["0000000000000000000000000000000000000000000000000000000000000100", 2, "0x51", 3000]],