trezorlib: finalize BTC API changes

- drop set_tx_api method and its usage from trezorctl
- drop _prepare_sign_tx which is not used anymore
- adapt trezorctl to new signing API
- make trezorctl signing smarter, ahead of moving it elsewhere

trezorctl

@@ -21,6 +21,7 @@
 # along with this library.  If not, see <http://www.gnu.org/licenses/>.
 
 import base64
+import decimal
 import json
 import os
 import sys
@@ -766,6 +767,7 @@ def get_public_node(connect, coin, address, curve, script_type, show_display):
 def sign_tx(connect, coin):
     client = connect()
     if coin in coins.tx_api:
+        coin_data = coins.by_name[coin]
         txapi = coins.tx_api[coin]
     else:
         click.echo('Coin "%s" is not recognized.' % coin, err=True)
@@ -774,8 +776,6 @@ def sign_tx(connect, coin):
         )
         sys.exit(1)
 
-    client.set_tx_api(txapi)
-
     def default_script_type(address_n):
         script_type = "address"
 
@@ -791,6 +791,7 @@ def sign_tx(connect, coin):
         return bytes.fromhex(txid), int(vout)
 
     inputs = []
+    txes = {}
     while True:
         click.echo()
         prev = click.prompt(
@@ -800,7 +801,15 @@ def sign_tx(connect, coin):
             break
         prev_hash, prev_index = prev
         address_n = click.prompt("BIP-32 path to derive the key", type=tools.parse_path)
-        amount = click.prompt("Input amount (satoshis)", type=int, default=0)
+        try:
+            tx = txapi[prev_hash]
+            txes[prev_hash] = tx
+            amount = tx.bin_outputs[prev_index].amount
+            click.echo("Prefilling input amount: {}".format(amount))
+        except Exception as e:
+            print(e)
+            click.echo("Failed to fetch transation. This might bite you later.")
+            amount = click.prompt("Input amount (satoshis)", type=int, default=0)
         sequence = click.prompt(
             "Sequence Number to use (RBF opt-in enabled by default)",
             type=int,
@@ -825,14 +834,14 @@ def sign_tx(connect, coin):
             script_type=script_type,
             sequence=sequence,
         )
-        if txapi.bip115:
+        if coin_data["bip115"]:
             prev_output = txapi.get_tx(prev_hash.hex()).bin_outputs[prev_index]
             new_input.prev_block_hash_bip115 = prev_output.block_hash
             new_input.prev_block_height_bip115 = prev_output.block_height
 
         inputs.append(new_input)
 
-    if txapi.bip115:
+    if coin_data["bip115"]:
         current_block_height = txapi.current_height()
         # Zencash recommendation for the better protection
         block_height = current_block_height - 300
@@ -878,14 +887,14 @@ def sign_tx(connect, coin):
             )
         )
 
-    tx_version = click.prompt("Transaction version", type=int, default=2)
-    tx_locktime = click.prompt("Transaction locktime", type=int, default=0)
-    tx_timestamp = click.prompt(
-        "Transaction timestamp (Capricoin)", type=int, default=None
-    )
+    signtx = proto.SignTx()
+    signtx.version = click.prompt("Transaction version", type=int, default=2)
+    signtx.lock_time = click.prompt("Transaction locktime", type=int, default=0)
+    if coin == "Capricoin":
+        signtx.timestamp = click.prompt("Transaction timestamp", type=int)
 
     _, serialized_tx = btc.sign_tx(
-        client, coin, inputs, outputs, tx_version, tx_locktime, timestamp=tx_timestamp
+        client, coin, inputs, outputs, details=signtx, prev_txes=txes
     )
 
     client.close()

trezorlib/btc.py

@@ -72,7 +72,22 @@ def verify_message(client, coin_name, address, signature, message):
 
 @session
 def sign_tx(client, coin_name, inputs, outputs, details=None, prev_txes=None):
-    my_tx = messages.TransactionType(inputs=inputs, outputs=outputs)
+    # set up a transactions dict
+    txes = {None: messages.TransactionType(inputs=inputs, outputs=outputs)}
+    # preload all relevant transactions ahead of time
+    for inp in inputs:
+        if inp.script_type not in (
+            messages.InputScriptType.SPENDP2SHWITNESS,
+            messages.InputScriptType.SPENDWITNESS,
+            messages.InputScriptType.EXTERNAL,
+        ):
+            try:
+                prev_tx = prev_txes[inp.prev_hash]
+            except Exception as e:
+                raise ValueError("Could not retrieve prev_tx") from e
+            if not isinstance(prev_tx, messages.TransactionType):
+                raise ValueError("Invalid value for prev_tx") from None
+            txes[inp.prev_hash] = prev_tx
 
     if details is None:
         signtx = messages.SignTx()
@@ -120,10 +135,7 @@ def sign_tx(client, coin_name, inputs, outputs, details=None, prev_txes=None):
             break
 
         # Device asked for one more information, let's process it.
-        if not res.details.tx_hash:
-            current_tx = my_tx
-        else:
-            current_tx = prev_txes[res.details.tx_hash]
+        current_tx = txes[res.details.tx_hash]
 
         if res.request_type == R.TXMETA:
             msg = copy_tx_meta(current_tx)

trezorlib/client.py

@@ -169,10 +169,9 @@ class ProtocolMixin(object):
         super(ProtocolMixin, self).__init__(*args, **kwargs)
         self.state = state
         self.init_device()
-        self.tx_api = None
 
     def set_tx_api(self, tx_api):
-        self.tx_api = tx_api
+        warnings.warn("set_tx_api is deprecated, use new arguments to sign_tx")
 
     def init_device(self):
         resp = self.call(proto.Initialize(state=self.state))
@@ -211,31 +210,6 @@ class ProtocolMixin(object):
     def get_device_id(self):
         return self.features.device_id
 
-    def _prepare_sign_tx(self, inputs, outputs):
-        tx = proto.TransactionType()
-        tx.inputs = inputs
-        tx.outputs = outputs
-
-        txes = {None: tx}
-
-        for inp in inputs:
-            if inp.prev_hash in txes:
-                continue
-
-            if inp.script_type in (
-                proto.InputScriptType.SPENDP2SHWITNESS,
-                proto.InputScriptType.SPENDWITNESS,
-            ):
-                continue
-
-            if not self.tx_api:
-                raise RuntimeError("TX_API not defined")
-
-            prev_tx = self.tx_api.get_tx(inp.prev_hash.hex())
-            txes[inp.prev_hash] = prev_tx
-
-        return txes
-
     @tools.expect(proto.Success, field="message")
     def clear_session(self):
         return self.call(proto.ClearSession())