From c5c85925e2ebde0e0b3ac993ca6034536ea6ae79 Mon Sep 17 00:00:00 2001
From: rbrunner7 <rbrunner@dreamshare.ch>
Date: Mon, 4 May 2020 11:31:46 +0200
Subject: [PATCH] [release-v0.16] MMS: New 'config_checksum' subcommand

---
 src/simplewallet/simplewallet.cpp |  42 +++++++++++-
 src/simplewallet/simplewallet.h   |   2 +
 src/wallet/message_store.cpp      | 104 +++++++++++++++++++++++-------
 src/wallet/message_store.h        |   3 +-
 4 files changed, 124 insertions(+), 27 deletions(-)

diff --git a/src/simplewallet/simplewallet.cpp b/src/simplewallet/simplewallet.cpp
index 585d7f8a1..df5bae08d 100644
--- a/src/simplewallet/simplewallet.cpp
+++ b/src/simplewallet/simplewallet.cpp
@@ -250,6 +250,7 @@ namespace
   const char* USAGE_MMS_SET("mms set <option_name> [<option_value>]");
   const char* USAGE_MMS_SEND_SIGNER_CONFIG("mms send_signer_config");
   const char* USAGE_MMS_START_AUTO_CONFIG("mms start_auto_config [<label> <label> ...]");
+  const char* USAGE_MMS_CONFIG_CHECKSUM("mms config_checksum");
   const char* USAGE_MMS_STOP_AUTO_CONFIG("mms stop_auto_config");
   const char* USAGE_MMS_AUTO_CONFIG("mms auto_config <auto_config_token>");
   const char* USAGE_PRINT_RING("print_ring <key_image> | <txid>");
@@ -3435,7 +3436,7 @@ simple_wallet::simple_wallet()
                            tr("Interface with the MMS (Multisig Messaging System)\n"
                               "<subcommand> is one of:\n"
                               "  init, info, signer, list, next, sync, transfer, delete, send, receive, export, note, show, set, help\n"
-                              "  send_signer_config, start_auto_config, stop_auto_config, auto_config\n"
+                              "  send_signer_config, start_auto_config, stop_auto_config, auto_config, config_checksum\n"
                               "Get help about a subcommand with: help mms <subcommand>, or mms help <subcommand>"));
   m_cmd_binder.set_handler("mms init",
                            boost::bind(&simple_wallet::on_command, this, &simple_wallet::mms, _1),
@@ -3504,6 +3505,10 @@ simple_wallet::simple_wallet()
                            boost::bind(&simple_wallet::on_command, this, &simple_wallet::mms, _1),
                            tr(USAGE_MMS_START_AUTO_CONFIG),
                            tr("Start auto-config at the auto-config manager's wallet by issuing auto-config tokens and optionally set others' labels"));
+  m_cmd_binder.set_handler("mms config_checksum",
+                           boost::bind(&simple_wallet::on_command, this, &simple_wallet::mms, _1),
+                           tr(USAGE_MMS_CONFIG_CHECKSUM),
+                           tr("Get a checksum that allows signers to easily check for identical MMS configuration"));
   m_cmd_binder.set_handler("mms stop_auto_config",
                            boost::bind(&simple_wallet::on_command, this, &simple_wallet::mms, _1),
                            tr(USAGE_MMS_STOP_AUTO_CONFIG),
@@ -10330,6 +10335,14 @@ bool simple_wallet::user_confirms(const std::string &question)
    return !std::cin.eof() && command_line::is_yes(answer);
 }
 
+bool simple_wallet::user_confirms_auto_config()
+{
+  message_writer(console_color_red, true) << tr("WARNING: Using MMS auto-config mechanisms is not trustless");
+  message_writer() << tr("A malicious auto-config manager could send you info about own wallets instead of other signers' info");
+  message_writer() << tr("If in doubt do not use auto-config or at least compare configs using the \"mms config_checksum\" command");
+  return user_confirms("Accept the risks and continue?");
+}
+
 bool simple_wallet::get_number_from_arg(const std::string &arg, uint32_t &number, const uint32_t lower_bound, const uint32_t upper_bound)
 {
   bool valid = false;
@@ -10482,7 +10495,7 @@ void simple_wallet::show_message(const mms::message &m)
   case mms::message_type::additional_key_set:
   case mms::message_type::note:
     display_content = true;
-    ms.get_sanitized_message_text(m, sanitized_text);
+    ms.get_sanitized_text(m.content, 1000, sanitized_text);
     break;
   default:
     display_content = false;
@@ -10831,6 +10844,11 @@ void simple_wallet::mms_next(const std::vector<std::string> &args)
         {
           break;
         }
+        if (!user_confirms_auto_config())
+        {
+          message_writer() << tr("You can use the \"mms delete\" command to delete any unwanted message");
+          break;
+        }
       }
       ms.process_signer_config(state, m.content);
       ms.stop_auto_config();
@@ -11157,6 +11175,18 @@ void simple_wallet::mms_start_auto_config(const std::vector<std::string> &args)
   list_signers(ms.get_all_signers());
 }
 
+void simple_wallet::mms_config_checksum(const std::vector<std::string> &args)
+{
+  if (args.size() != 0)
+  {
+    fail_msg_writer() << tr("Usage: mms config_checksum");
+    return;
+  }
+  mms::message_store& ms = m_wallet->get_message_store();
+  LOCK_IDLE_SCOPE();
+  message_writer() << ms.get_config_checksum();
+}
+
 void simple_wallet::mms_stop_auto_config(const std::vector<std::string> &args)
 {
   if (args.size() != 0)
@@ -11187,6 +11217,10 @@ void simple_wallet::mms_auto_config(const std::vector<std::string> &args)
     fail_msg_writer() << tr("Invalid auto-config token");
     return;
   }
+  if (!user_confirms_auto_config())
+  {
+    return;
+  }
   mms::authorized_signer me = ms.get_signer(0);
   if (me.auto_config_running)
   {
@@ -11299,6 +11333,10 @@ bool simple_wallet::mms(const std::vector<std::string> &args)
     {
       mms_start_auto_config(mms_args);
     }
+    else if (sub_command == "config_checksum")
+    {
+      mms_config_checksum(mms_args);
+    }
     else if (sub_command == "stop_auto_config")
     {
       mms_stop_auto_config(mms_args);
diff --git a/src/simplewallet/simplewallet.h b/src/simplewallet/simplewallet.h
index b1f77567e..8f9d6df92 100644
--- a/src/simplewallet/simplewallet.h
+++ b/src/simplewallet/simplewallet.h
@@ -477,6 +477,7 @@ namespace cryptonote
     void ask_send_all_ready_messages();
     void check_for_messages();
     bool user_confirms(const std::string &question);
+    bool user_confirms_auto_config();
     bool get_message_from_arg(const std::string &arg, mms::message &m);
     bool get_number_from_arg(const std::string &arg, uint32_t &number, const uint32_t lower_bound, const uint32_t upper_bound); 
 
@@ -497,6 +498,7 @@ namespace cryptonote
     void mms_help(const std::vector<std::string> &args);
     void mms_send_signer_config(const std::vector<std::string> &args);
     void mms_start_auto_config(const std::vector<std::string> &args);
+    void mms_config_checksum(const std::vector<std::string> &args);
     void mms_stop_auto_config(const std::vector<std::string> &args);
     void mms_auto_config(const std::vector<std::string> &args);
   };
diff --git a/src/wallet/message_store.cpp b/src/wallet/message_store.cpp
index 25a8bd4ef..699195d6d 100644
--- a/src/wallet/message_store.cpp
+++ b/src/wallet/message_store.cpp
@@ -39,6 +39,7 @@
 #include "serialization/binary_utils.h"
 #include "common/base58.h"
 #include "common/util.h"
+#include "common/utf8.h"
 #include "string_tools.h"
 
 
@@ -129,18 +130,18 @@ void message_store::set_signer(const multisig_wallet_state &state,
   authorized_signer &m = m_signers[index];
   if (label)
   {
-    m.label = label.get();
+    get_sanitized_text(label.get(), 50, m.label);
   }
   if (transport_address)
   {
-    m.transport_address = transport_address.get();
+    get_sanitized_text(transport_address.get(), 200, m.transport_address);
   }
   if (monero_address)
   {
     m.monero_address_known = true;
     m.monero_address = monero_address.get();
   }
-  // Save to minimize the chance to loose that info (at least while in beta)
+  // Save to minimize the chance to loose that info
   save(state);
 }
 
@@ -202,6 +203,17 @@ void message_store::unpack_signer_config(const multisig_wallet_state &state, con
   }
   uint32_t num_signers = (uint32_t)signers.size();
   THROW_WALLET_EXCEPTION_IF(num_signers != m_num_authorized_signers, tools::error::wallet_internal_error, "Wrong number of signers in config: " + std::to_string(num_signers));
+  for (uint32_t i = 0; i < num_signers; ++i)
+  {
+    authorized_signer &m = signers[i];
+    std::string temp;
+    get_sanitized_text(m.label, 50, temp);
+    m.label = temp;
+    get_sanitized_text(m.transport_address, 200, temp);
+    m.transport_address = temp;
+    get_sanitized_text(m.auto_config_token, 20, temp);
+    m.auto_config_token = temp;
+  }
 }
 
 void message_store::process_signer_config(const multisig_wallet_state &state, const std::string &signer_config)
@@ -242,10 +254,10 @@ void message_store::process_signer_config(const multisig_wallet_state &state, co
       }
     }
     authorized_signer &modify = m_signers[take_index];
-    modify.label = m.label;  // ALWAYS set label, see comments above
+    get_sanitized_text(m.label, 50, modify.label);  // ALWAYS set label, see comments above
     if (!modify.me)
     {
-      modify.transport_address = m.transport_address;
+      get_sanitized_text(m.transport_address, 200, modify.transport_address);
       modify.monero_address_known = m.monero_address_known;
       if (m.monero_address_known)
       {
@@ -392,6 +404,45 @@ void message_store::process_auto_config_data_message(uint32_t id)
   signer.auto_config_running = false;
 }
 
+void add_hash(crypto::hash &sum, const crypto::hash &summand)
+{
+  for (uint32_t i = 0; i < crypto::HASH_SIZE; ++i)
+  {
+    uint32_t x = (uint32_t)sum.data[i];
+    uint32_t y = (uint32_t)summand.data[i];
+    sum.data[i] = (char)((x + y) % 256);
+  }
+}
+
+// Calculate a checksum that allows signers to make sure they work with an identical signer config
+// by exchanging and comparing checksums out-of-band i.e. not using the MMS;
+// Because different signers have a different order of signers in the config work with "adding"
+// individual hashes because that operation is commutative
+std::string message_store::get_config_checksum() const
+{
+  crypto::hash sum = crypto::null_hash;
+  uint32_t num = SWAP32LE(m_num_authorized_signers);
+  add_hash(sum, crypto::cn_fast_hash(&num, sizeof(num)));
+  num = SWAP32LE(m_num_required_signers);
+  add_hash(sum, crypto::cn_fast_hash(&num, sizeof(num)));
+  for (uint32_t i = 0; i < m_num_authorized_signers; ++i)
+  {
+    const authorized_signer &m = m_signers[i];
+    add_hash(sum, crypto::cn_fast_hash(m.transport_address.data(), m.transport_address.size()));
+    if (m.monero_address_known)
+    {
+      add_hash(sum, crypto::cn_fast_hash(&m.monero_address.m_spend_public_key, sizeof(m.monero_address.m_spend_public_key)));
+      add_hash(sum, crypto::cn_fast_hash(&m.monero_address.m_view_public_key, sizeof(m.monero_address.m_view_public_key)));
+    }
+  }
+  std::string checksum_bytes;
+  checksum_bytes += sum.data[0];
+  checksum_bytes += sum.data[1];
+  checksum_bytes += sum.data[2];
+  checksum_bytes += sum.data[3];
+  return epee::string_tools::buff_to_hex_nodelimer(checksum_bytes);
+}
+
 void message_store::stop_auto_config()
 {
   for (uint32_t i = 0; i < m_num_authorized_signers; ++i)
@@ -661,31 +712,36 @@ void message_store::delete_all_messages()
   m_messages.clear();
 }
 
-// Make a message text, which is "attacker controlled data", reasonably safe to display
+// Make a text, which is "attacker controlled data", reasonably safe to display
 // This is mostly geared towards the safe display of notes sent by "mms note" with a "mms show" command
-void message_store::get_sanitized_message_text(const message &m, std::string &sanitized_text) const
+void message_store::get_sanitized_text(const std::string &text, size_t max_length, std::string &sanitized_text) const
 {
-  sanitized_text.clear();
-
   // Restrict the size to fend of DOS-style attacks with heaps of data
-  size_t length = std::min(m.content.length(), (size_t)1000);
+  size_t length = std::min(text.length(), max_length);
+  sanitized_text = text.substr(0, length);
 
-  for (size_t i = 0; i < length; ++i)
+  try
   {
-    char c = m.content[i];
-    if ((int)c < 32)
+    sanitized_text = tools::utf8canonical(sanitized_text, [](wint_t c)
     {
-      // Strip out any controls, especially ESC for getting rid of potentially dangerous
-      // ANSI escape sequences that a console window might interpret
-      c = ' ';
-    }
-    else if ((c == '<') || (c == '>'))
-    {
-      // Make XML or HTML impossible that e.g. might contain scripts that Qt might execute
-      // when displayed in the GUI wallet
-      c = ' ';
-    }
-    sanitized_text += c;
+      if ((c < 0x20) || (c == 0x7f) || (c >= 0x80 && c <= 0x9f))
+      {
+        // Strip out any controls, especially ESC for getting rid of potentially dangerous
+        // ANSI escape sequences that a console window might interpret
+        c = '?';
+      }
+      else if ((c == '<') || (c == '>'))
+      {
+        // Make XML or HTML impossible that e.g. might contain scripts that Qt might execute
+        // when displayed in the GUI wallet
+        c = '?';
+      }
+      return c;
+    });
+  }
+  catch (const std::exception &e)
+  {
+    sanitized_text = "(Illegal UTF-8 string)";
   }
 }
 
diff --git a/src/wallet/message_store.h b/src/wallet/message_store.h
index d40daf186..23dde5c3c 100644
--- a/src/wallet/message_store.h
+++ b/src/wallet/message_store.h
@@ -242,6 +242,7 @@ namespace mms
     size_t add_auto_config_data_message(const multisig_wallet_state &state,
                                         const std::string &auto_config_token);
     void process_auto_config_data_message(uint32_t id);
+    std::string get_config_checksum() const;
     void stop_auto_config();
 
     // Process data just created by "me" i.e. the own local wallet, e.g. as the result of a "prepare_multisig" command
@@ -275,7 +276,7 @@ namespace mms
     void set_message_processed_or_sent(uint32_t id);
     void delete_message(uint32_t id);
     void delete_all_messages();
-    void get_sanitized_message_text(const message &m, std::string &sanitized_text) const;
+    void get_sanitized_text(const std::string &text, size_t max_length, std::string &sanitized_text) const;
 
     void send_message(const multisig_wallet_state &state, uint32_t id);
     bool check_for_messages(const multisig_wallet_state &state, std::vector<message> &messages);