[Enhancement] Parse psbts with OP_RETURN data & display payload

src/seedsigner/gui/screens/psbt_screens.py

@@ -1,4 +1,5 @@
 from dataclasses import dataclass
+import math
 from PIL import Image, ImageDraw, ImageFilter
 from typing import List
 import time
@@ -21,6 +22,7 @@ class PSBTOverviewScreen(ButtonListScreen):
     num_self_transfer_outputs: int = 0
     num_change_outputs: int = 0
     destination_addresses: List[str] = None
+    has_op_return: bool = False
 
 
     def __post_init__(self):
@@ -143,6 +145,9 @@ def truncate_destination_addr(addr):
 
             destination_column.append(f"fee")
 
+            if self.has_op_return:
+                destination_column.append("OP_RETURN")
+
             if self.num_change_outputs > 0:
                 for i in range(0, self.num_change_outputs):
                     destination_column.append("change")
@@ -681,6 +686,57 @@ def __post_init__(self):
 
 
 
+@dataclass
+class PSBTOpReturnScreen(ButtonListScreen):
+    op_return_data: bytes = None
+
+    def __post_init__(self):
+        # Customize defaults
+        self.is_bottom_list = True
+
+        super().__post_init__()
+
+        try:
+            # Simple case: display human-readable text
+            self.components.append(TextArea(
+                text=self.op_return_data.decode(errors="strict"),  # "strict" is a good enough heuristic to decide if it's human readable
+                font_size=GUIConstants.TOP_NAV_TITLE_FONT_SIZE,
+                is_text_centered=True,
+                allow_text_overflow=True,
+                screen_y=self.top_nav.height + GUIConstants.COMPONENT_PADDING,
+                height=self.buttons[0].screen_y - self.top_nav.height - 2*GUIConstants.COMPONENT_PADDING,
+            ))
+            return
+        except UnicodeDecodeError:
+            # Contains data that can't be converted to UTF-8; probably encoded and not
+            # meant to be human readable.
+            font = Fonts.get_font(GUIConstants.FIXED_WIDTH_FONT_NAME, size=GUIConstants.BODY_FONT_SIZE)
+            (left, top, right, bottom) = font.getbbox("X", anchor="ls")
+            chars_per_line = int((self.canvas_width - 2*GUIConstants.EDGE_PADDING) / (right - left))
+            decoded_str = self.op_return_data.hex()
+            num_lines = math.ceil(len(decoded_str) / chars_per_line)
+            text = ""
+            for i in range(num_lines):
+                text += (decoded_str[i*chars_per_line:(i+1)*chars_per_line]) + "\n"
+            text = text[:-1]
+
+            label = TextArea(
+                text="raw hex data",
+                font_color=GUIConstants.LABEL_FONT_COLOR,
+                font_size=GUIConstants.LABEL_FONT_SIZE,
+                screen_y=self.top_nav.height,
+            )
+            self.components.append(label)
+
+            self.components.append(TextArea(
+                text=text,
+                font_name=GUIConstants.FIXED_WIDTH_FONT_NAME,
+                font_size=GUIConstants.BODY_FONT_SIZE,
+                screen_y=label.screen_y + label.height + GUIConstants.COMPONENT_PADDING,
+            ))
+
+
+
 @dataclass
 class PSBTFinalizeScreen(ButtonListScreen):
     def __post_init__(self):

src/seedsigner/gui/screens/seed_screens.py

@@ -1511,6 +1511,8 @@ def __post_init__(self):
         end_y = renderer.canvas_height - GUIConstants.EDGE_PADDING - GUIConstants.BUTTON_HEIGHT - GUIConstants.COMPONENT_PADDING
         message_height = end_y - start_y
 
+        # TODO: Pass the full message in from the View so that this Screen doesn't need to
+        # interact with the Controller here.
         self.sign_message_data = Controller.get_instance().sign_message_data
         if "paged_message" not in self.sign_message_data:
             paged = reflow_text_into_pages(

src/seedsigner/models/psbt_parser.py

@@ -10,6 +10,11 @@
 from seedsigner.models.settings import SettingsConstants
 
 
+class OPCODES:
+    OP_RETURN = 106
+    OP_PUSHDATA1 = 76
+
+
 
 class PSBTParser():
     def __init__(self, p: PSBT, seed: Seed, network: str = SettingsConstants.MAINNET):
@@ -26,6 +31,7 @@ def __init__(self, p: PSBT, seed: Seed, network: str = SettingsConstants.MAINNET
         self.num_inputs = 0
         self.destination_addresses = []
         self.destination_amounts = []
+        self.op_return_data: bytes = None
 
         self.root = None
 
@@ -169,7 +175,11 @@ def _parse_outputs(self):
                 if sc.data == self.psbt.tx.vout[i].script_pubkey.data:
                     is_change = True
 
-            if is_change:
+            if self.psbt.tx.vout[i].script_pubkey.data[0] == OPCODES.OP_RETURN:
+                # The data is written as: OP_RETURN + OP_PUSHDATA1 + len(payload) + payload
+                self.op_return_data = self.psbt.tx.vout[i].script_pubkey.data[3:]
+
+            elif is_change:
                 addr = self.psbt.tx.vout[i].script_pubkey.address(NETWORKS[SettingsConstants.map_network_to_embit(self.network)])
                 fingerprints = []
                 derivation_paths = []
@@ -252,21 +262,22 @@ def _get_policy(scope, scriptpubkey, xpubs):
 
         # expected multisig
         script = None
-        if "p2wsh" in script_type and scope.witness_script is not None:
-            script = scope.witness_script
-
-        elif "p2sh" in script_type and scope.redeem_script is not None:
-            script = scope.redeem_script
-
-        if script is not None:
-            m, n, pubkeys = PSBTParser._parse_multisig(script)
-
-            # check pubkeys are derived from cosigners
-            try:
-                cosigners = PSBTParser._get_cosigners(pubkeys, scope.bip32_derivations, xpubs)
-                policy.update({"m": m, "n": n, "cosigners": cosigners})
-            except:
-                policy.update({"m": m, "n": n})
+        if script_type:
+            if "p2wsh" in script_type and scope.witness_script is not None:
+                script = scope.witness_script
+
+            elif "p2sh" in script_type and scope.redeem_script is not None:
+                script = scope.redeem_script
+
+            if script is not None:
+                m, n, pubkeys = PSBTParser._parse_multisig(script)
+
+                # check pubkeys are derived from cosigners
+                try:
+                    cosigners = PSBTParser._get_cosigners(pubkeys, scope.bip32_derivations, xpubs)
+                    policy.update({"m": m, "n": n, "cosigners": cosigners})
+                except:
+                    policy.update({"m": m, "n": n})
 
         return policy
 

src/seedsigner/views/psbt_views.py

@@ -7,7 +7,7 @@
 from seedsigner.models.encode_qr import UrPsbtQrEncoder
 from seedsigner.models.psbt_parser import PSBTParser
 from seedsigner.models.settings import SettingsConstants
-from seedsigner.gui.screens.psbt_screens import PSBTOverviewScreen, PSBTMathScreen, PSBTAddressDetailsScreen, PSBTChangeDetailsScreen, PSBTFinalizeScreen
+from seedsigner.gui.screens.psbt_screens import PSBTOpReturnScreen, PSBTOverviewScreen, PSBTMathScreen, PSBTAddressDetailsScreen, PSBTChangeDetailsScreen, PSBTFinalizeScreen
 from seedsigner.gui.screens.screen import (RET_CODE__BACK_BUTTON, ButtonListScreen, WarningScreen, DireWarningScreen, QRDisplayScreen)
 from seedsigner.views.view import BackStackView, MainMenuView, NotYetImplementedView, View, Destination
 
@@ -137,7 +137,8 @@ def run(self):
             num_inputs=psbt_parser.num_inputs,
             num_self_transfer_outputs=num_self_transfer_outputs,
             num_change_outputs=num_change_outputs,
-            destination_addresses=psbt_parser.destination_addresses
+            destination_addresses=psbt_parser.destination_addresses,
+            has_op_return=psbt_parser.op_return_data is not None,
         )
 
         if selected_menu_num == RET_CODE__BACK_BUTTON:
@@ -276,12 +277,14 @@ def run(self):
             # Move on to display change
             return Destination(PSBTChangeDetailsView, view_args={"change_address_num": 0})
 
+        elif psbt_parser.op_return_data:
+            return Destination(PSBTOpReturnView)
+
         else:
             # There's no change output to verify. Move on to sign the PSBT.
             return Destination(PSBTFinalizeView)
 
 
-
 class PSBTChangeDetailsView(View):
     NEXT = "Next"
     SKIP_VERIFICATION = "Skip Verificiation"
@@ -417,6 +420,10 @@ def run(self):
 
             if self.change_address_num < psbt_parser.num_change_outputs - 1:
                 return Destination(PSBTChangeDetailsView, view_args={"change_address_num": self.change_address_num + 1})
+
+            elif psbt_parser.op_return_data:
+                return Destination(PSBTOpReturnView)
+
             else:
                 # There's no more change to verify. Move on to sign the PSBT.
                 return Destination(PSBTFinalizeView)
@@ -456,6 +463,33 @@ def run(self):
         return Destination(MainMenuView, clear_history=True)
 
 
+class PSBTOpReturnView(View):
+    """
+        Shows the OP_RETURN data
+    """
+    def run(self):
+        psbt_parser: PSBTParser = self.controller.psbt_parser
+
+        if not psbt_parser:
+            # Should not be able to get here
+            raise Exception("Routing error")
+
+        title = "OP_RETURN"
+        button_data = ["Next"]
+
+        selected_menu_num = self.run_screen(
+            PSBTOpReturnScreen,
+            title=title,
+            button_data=button_data,
+            op_return_data=psbt_parser.op_return_data,
+        )
+
+        if selected_menu_num == RET_CODE__BACK_BUTTON:
+            return Destination(BackStackView)
+
+        return Destination(PSBTFinalizeView)
+
+
 
 class PSBTFinalizeView(View):
     """

tests/screenshot_generator/generator.py

@@ -1,11 +1,17 @@
 import embit
 import os
+import random
 import sys
 import time
 from unittest.mock import Mock, patch, MagicMock
 from seedsigner.helpers import embit_utils
 
-from seedsigner.models.settings import Settings
+from embit import compact
+from embit.psbt import PSBT, OutputScope
+from embit.script import Script
+
+from seedsigner.helpers import embit_utils
+from seedsigner.models.psbt_parser import OPCODES, PSBTParser
 
 
 # Prevent importing modules w/Raspi hardware dependencies.
@@ -22,8 +28,6 @@
 from seedsigner.controller import Controller
 from seedsigner.gui.renderer import Renderer
 from seedsigner.gui.toast import BaseToastOverlayManagerThread, RemoveSDCardToastManagerThread, SDCardStateChangeToastManagerThread
-from seedsigner.hardware.buttons import HardwareButtons
-from seedsigner.hardware.camera import Camera
 from seedsigner.hardware.microsd import MicroSD
 from seedsigner.models.decode_qr import DecodeQR
 from seedsigner.models.qr_type import QRType
@@ -86,6 +90,34 @@ def test_generate_screenshots(target_locale):
     controller.psbt = decoder.get_psbt()
     controller.psbt_seed = seed_12b
 
+    def add_op_return_to_psbt(psbt: PSBT, raw_payload_data: bytes):
+        data = (compact.to_bytes(OPCODES.OP_RETURN) + 
+            compact.to_bytes(OPCODES.OP_PUSHDATA1) + 
+            compact.to_bytes(len(raw_payload_data)) +
+            raw_payload_data)
+        script = Script(data)
+        output = OutputScope()
+        output.script_pubkey = script
+        output.value = 0
+        psbt.outputs.append(output)
+        return psbt.to_string()
+
+    # Prep a PSBT with a human-readable OP_RETURN
+    raw_payload_data = "Chancellor on the brink of third bailout for banks".encode()
+    psbt = PSBT.from_base64(BASE64_PSBT_1)
+
+    # Simplify the output side
+    output = psbt.outputs[-1]
+    psbt.outputs.clear()
+    psbt.outputs.append(output)
+    assert len(psbt.outputs) == 1
+    BASE64_PSBT_WITH_OP_RETURN_TEXT = add_op_return_to_psbt(psbt, raw_payload_data)
+
+    # Prep a PSBT with a (repeatably) random 80-byte OP_RETURN
+    random.seed(6102)
+    BASE64_PSBT_WITH_OP_RETURN_RAW_BYTES = add_op_return_to_psbt(PSBT.from_base64(BASE64_PSBT_1), random.randbytes(80))
+
+
     # Multisig wallet descriptor for the multisig in the above PSBT
     MULTISIG_WALLET_DESCRIPTOR = """wsh(sortedmulti(1,[22bde1a9/48h/1h/0h/2h]tpubDFfsBrmpj226ZYiRszYi2qK6iGvh2vkkghfGB2YiRUVY4rqqedHCFEgw12FwDkm7rUoVtq9wLTKc6BN2sxswvQeQgp7m8st4FP8WtP8go76/{0,1}/*,[73c5da0a/48h/1h/0h/2h]tpubDFH9dgzveyD8zTbPUFuLrGmCydNvxehyNdUXKJAQN8x4aZ4j6UZqGfnqFrD4NqyaTVGKbvEW54tsvPTK2UoSbCC1PJY8iCNiwTL3RWZEheQ/{0,1}/*))#3jhtf6yx"""
     controller.multisig_wallet_descriptor = embit.descriptor.Descriptor.from_string(MULTISIG_WALLET_DESCRIPTOR)
@@ -193,6 +225,11 @@ def test_generate_screenshots(target_locale):
 
             (NotYetImplementedView, {}, "PSBTChangeDetailsView_multisig_unverified"),  # Must manually re-run this below
             (psbt_views.PSBTChangeDetailsView, dict(change_address_num=0), "PSBTChangeDetailsView_multisig_verified"),
+
+            (NotYetImplementedView, {}, "PSBTOverviewView_op_return"),  # Placeholder
+            (NotYetImplementedView, {}, "PSBTOpReturnView_text"),       # Placeholder
+            (NotYetImplementedView, {}, "PSBTOpReturnView_raw_hex_data"),  # Placeholder
+
             (psbt_views.PSBTAddressVerificationFailedView, dict(is_change=True, is_multisig=False), "PSBTAddressVerificationFailedView_singlesig_change"),
             (psbt_views.PSBTAddressVerificationFailedView, dict(is_change=False, is_multisig=False), "PSBTAddressVerificationFailedView_singlesig_selftransfer"),
             (psbt_views.PSBTAddressVerificationFailedView, dict(is_change=True, is_multisig=True), "PSBTAddressVerificationFailedView_multisig_change"),
@@ -241,7 +278,9 @@ def test_generate_screenshots(target_locale):
 
     readme = f"""# SeedSigner Screenshots\n"""
 
-    def screencap_view(view_cls: View, view_name: str, view_args: dict={}, toast_thread: BaseToastOverlayManagerThread = None):
+    def screencap_view(view_cls: View, view_args: dict = {}, view_name: str = None, toast_thread: BaseToastOverlayManagerThread = None):
+        if not view_name:
+            view_name = view_cls.__name__
         screenshot_renderer.set_screenshot_filename(f"{view_name}.png")
         try:
             print(f"Running {view_name}")
@@ -266,7 +305,6 @@ def screencap_view(view_cls: View, view_name: str, view_args: dict={}, toast_thr
             if toast_thread:
                 toast_thread.stop()
 
-
     for section_name, screenshot_list in screenshot_sections.items():
         subdir = section_name.lower().replace(" ", "_")
         screenshot_renderer.set_screenshot_path(os.path.join(screenshot_root, subdir))
@@ -289,25 +327,41 @@ def screencap_view(view_cls: View, view_name: str, view_args: dict={}, toast_thr
                 view_name = view_cls.__name__
                 toast_thread = None
 
-            screencap_view(view_cls, view_name, view_args, toast_thread=toast_thread)
+            screencap_view(view_cls, view_args=view_args, view_name=view_name, toast_thread=toast_thread)
             readme += """  <table align="left" style="border: 1px solid gray;">"""
             readme += f"""<tr><td align="center">{view_name}<br/><br/><img src="{subdir}/{view_name}.png"></td></tr>"""
             readme += """</table>\n"""
 
         readme += "</td></tr></table>"
 
-    # many screens don't work, leaving a missing image, re-run here for now
+    # Re-render some screens that require more manual intervention / setup than the above
+    # scripting can support.
     screenshot_renderer.set_screenshot_path(os.path.join(screenshot_root, "psbt_views"))
 
+    # Render the PSBTChangeDetailsView_multisig_unverified screenshot
     decoder = DecodeQR()
     decoder.add_data(BASE64_PSBT_1)
     controller.psbt = decoder.get_psbt()
     controller.psbt_seed = seed_12b
     controller.multisig_wallet_descriptor = None
-    screencap_view(psbt_views.PSBTChangeDetailsView, 'PSBTChangeDetailsView_multisig_unverified', dict(change_address_num=0))
+    screencap_view(psbt_views.PSBTChangeDetailsView, view_name='PSBTChangeDetailsView_multisig_unverified', view_args=dict(change_address_num=0))
 
     controller.psbt_seed = None
-    screencap_view(psbt_views.PSBTSelectSeedView, 'PSBTSelectSeedView', {})
+    screencap_view(psbt_views.PSBTSelectSeedView, view_name='PSBTSelectSeedView')
+
+    # Render OP_RETURN screens for real
+    controller.psbt_seed = seed_12b
+    decoder = DecodeQR()
+    decoder.add_data(BASE64_PSBT_WITH_OP_RETURN_TEXT)
+    controller.psbt = decoder.get_psbt()
+    controller.psbt_parser = PSBTParser(p=controller.psbt, seed=seed_12b)
+    screencap_view(psbt_views.PSBTOverviewView, view_name='PSBTOverviewView_op_return')
+    screencap_view(psbt_views.PSBTOpReturnView, view_name="PSBTOpReturnView_text")
+
+    decoder.add_data(BASE64_PSBT_WITH_OP_RETURN_RAW_BYTES)
+    controller.psbt = decoder.get_psbt()
+    controller.psbt_parser = PSBTParser(p=controller.psbt, seed=seed_12b)
+    screencap_view(psbt_views.PSBTOpReturnView, view_name="PSBTOpReturnView_raw_hex_data")
 
     with open(os.path.join(screenshot_root, "README.md"), 'w') as readme_file:
        readme_file.write(readme)