core/bitcoin: Add special confirmation screen for transactions with external inputs.

core/src/apps/bitcoin/sign_tx/__init__.py

@@ -55,6 +55,13 @@ async def sign_tx(
             res = await layout.confirm_total(ctx, req.spending, req.fee, req.coin)
             utils.unimport_end(mods)
             progress.report_init()
+        elif isinstance(req, helpers.UiConfirmJointTotal):
+            mods = utils.unimport_begin()
+            res = await layout.confirm_joint_total(
+                ctx, req.spending, req.total, req.coin
+            )
+            utils.unimport_end(mods)
+            progress.report_init()
         elif isinstance(req, helpers.UiConfirmFeeOverThreshold):
             mods = utils.unimport_begin()
             res = await layout.confirm_feeoverthreshold(ctx, req.fee, req.coin)

core/src/apps/bitcoin/sign_tx/bitcoin.py

@@ -148,14 +148,18 @@ class Bitcoin:
         if fee < 0:
             self.on_negative_fee()
 
+        total = self.total_in - self.change_out
+        spending = total - self.external_in
+
         # fee > (coin.maxfee per byte * tx size)
         if fee > (self.coin.maxfee_kb / 1000) * (self.weight.get_total() / 4):
             await helpers.confirm_feeoverthreshold(fee, self.coin)
         if self.tx.lock_time > 0:
             await helpers.confirm_nondefault_locktime(self.tx.lock_time)
-        await helpers.confirm_total(
-            self.total_in - self.external_in - self.change_out, fee, self.coin
-        )
+        if not self.external:
+            await helpers.confirm_total(total, fee, self.coin)
+        else:
+            await helpers.confirm_joint_total(spending, total, self.coin)
 
     async def step4_verify_external_inputs(self) -> None:
         # should come out the same as h_external, checked before continuing

core/src/apps/bitcoin/sign_tx/helpers.py

@@ -46,6 +46,15 @@ class UiConfirmTotal:
     __eq__ = utils.obj_eq
 
 
+class UiConfirmJointTotal:
+    def __init__(self, spending: int, total: int, coin: CoinInfo):
+        self.spending = spending
+        self.total = total
+        self.coin = coin
+
+    __eq__ = utils.obj_eq
+
+
 class UiConfirmFeeOverThreshold:
     def __init__(self, fee: int, coin: CoinInfo):
         self.fee = fee
@@ -76,6 +85,10 @@ def confirm_total(spending: int, fee: int, coin: CoinInfo) -> Awaitable[Any]:  #
     return (yield UiConfirmTotal(spending, fee, coin))
 
 
+def confirm_joint_total(spending: int, total: int, coin: CoinInfo) -> Awaitable[Any]:  # type: ignore
+    return (yield UiConfirmJointTotal(spending, total, coin))
+
+
 def confirm_feeoverthreshold(fee: int, coin: CoinInfo) -> Awaitable[Any]:  # type: ignore
     return (yield UiConfirmFeeOverThreshold(fee, coin))
 

core/src/apps/bitcoin/sign_tx/layout.py

@@ -58,6 +58,20 @@ async def confirm_output(
     await require_confirm(ctx, text, ButtonRequestType.ConfirmOutput)
 
 
+async def confirm_joint_total(
+    ctx: wire.Context, spending: int, total: int, coin: coininfo.CoinInfo
+) -> None:
+    from trezor.ui.text import Text
+    from apps.common.confirm import require_hold_to_confirm
+
+    text = Text("Joint transaction", ui.ICON_SEND, ui.GREEN)
+    text.normal("You are contributing:")
+    text.bold(format_coin_amount(spending, coin))
+    text.normal("to the total amount:")
+    text.bold(format_coin_amount(total, coin))
+    await require_hold_to_confirm(ctx, text, ButtonRequestType.SignTx)
+
+
 async def confirm_total(
     ctx: wire.Context, spending: int, fee: int, coin: coininfo.CoinInfo
 ) -> None: