From ecec6e5d33e3fd9da70945745e6e3e395d168fd0 Mon Sep 17 00:00:00 2001
From: Bronek Kozicki <brok@incorrekt.com>
Date: Tue, 17 Dec 2024 15:38:27 +0000
Subject: [PATCH] Fix failing MPToken payment test

---
 src/xrpld/app/tx/detail/VaultDeposit.cpp | 29 ++++++++++---------
 src/xrpld/ledger/View.h                  | 15 ++++++++++
 src/xrpld/ledger/detail/View.cpp         | 37 +++++++++++++++++++-----
 3 files changed, 61 insertions(+), 20 deletions(-)

diff --git a/src/xrpld/app/tx/detail/VaultDeposit.cpp b/src/xrpld/app/tx/detail/VaultDeposit.cpp
index 810d97d3f6..7d340d35b0 100644
--- a/src/xrpld/app/tx/detail/VaultDeposit.cpp
+++ b/src/xrpld/app/tx/detail/VaultDeposit.cpp
@@ -81,20 +81,23 @@ VaultDeposit::doApply()
 
     // Make sure the depositor can hold shares.
     auto share = (*vault)[sfMPTokenIssuanceID];
-    auto canHold = requireAuth(view(), MPTIssue(share), account_);
-    if (canHold == tecNO_LINE)
+    auto maybeToken = findToken(view(), MPTIssue(share), account_);
+    if (!maybeToken)
     {
-        if (auto ter = MPTokenAuthorize::authorize(
-            view(),
-            j_,
-            {.priorBalance = mPriorBalance,
-             .mptIssuanceID = share,
-             .accountID = account_}))
-            return ter;
-    }
-    else if (canHold != tesSUCCESS)
-    {
-        return canHold;
+        if (maybeToken.error() == tecNO_LINE)
+        {
+            if (auto ter = MPTokenAuthorize::authorize(
+                    view(),
+                    j_,
+                    {.priorBalance = mPriorBalance,
+                     .mptIssuanceID = share,
+                     .accountID = account_}))
+                return ter;
+        }
+        else if (maybeToken.error() != tesSUCCESS)
+        {
+            return maybeToken.error();
+        }
     }
 
     // Compute exchange before transferring any amounts.
diff --git a/src/xrpld/ledger/View.h b/src/xrpld/ledger/View.h
index 8680a4e64a..4e4899de62 100644
--- a/src/xrpld/ledger/View.h
+++ b/src/xrpld/ledger/View.h
@@ -561,6 +561,21 @@ transferXRP(
     STAmount const& amount,
     beast::Journal j);
 
+struct TokenDescriptor
+{
+    std::shared_ptr<SLE const> token;
+    std::shared_ptr<SLE const> issuance;
+};
+
+[[nodiscard]] Expected<TokenDescriptor, TER>
+findToken(
+    ReadView const& view,
+    MPTIssue const& mptIssue,
+    AccountID const& account);
+
+[[nodiscard]] TER
+requireAuth(ReadView const& view, Issue const& issue, AccountID const& account);
+
 /** Check if the account lacks required authorization.
  *   Return tecNO_AUTH or tecNO_LINE if it does
  *   and tesSUCCESS otherwise.
diff --git a/src/xrpld/ledger/detail/View.cpp b/src/xrpld/ledger/detail/View.cpp
index abc4669c9c..a70c036f54 100644
--- a/src/xrpld/ledger/detail/View.cpp
+++ b/src/xrpld/ledger/detail/View.cpp
@@ -2021,8 +2021,8 @@ requireAuth(ReadView const& view, Issue const& issue, AccountID const& account)
     return tesSUCCESS;
 }
 
-TER
-requireAuth(
+[[nodiscard]] Expected<TokenDescriptor, TER>
+findToken(
     ReadView const& view,
     MPTIssue const& mptIssue,
     AccountID const& account)
@@ -2031,20 +2031,43 @@ requireAuth(
     auto const sleIssuance = view.read(mptID);
 
     if (!sleIssuance)
-        return tecOBJECT_NOT_FOUND;
+        return Unexpected(tecOBJECT_NOT_FOUND);
 
     auto const mptIssuer = sleIssuance->getAccountID(sfIssuer);
-
-    // issuer is always "authorized"
+    // Issuer won't have mptoken, i.e. "the operation failed succcessfully"
     if (mptIssuer == account)
-        return tesSUCCESS;
+        return Unexpected(tesSUCCESS);
 
     auto const mptokenID = keylet::mptoken(mptID.key, account);
     auto const sleToken = view.read(mptokenID);
 
     // if account has no MPToken, fail
     if (!sleToken)
-        return tecNO_LINE;
+        return Unexpected(tecNO_LINE);
+
+    return {TokenDescriptor{.token = sleToken, .issuance = sleIssuance}};
+}
+
+TER
+requireAuth(
+    ReadView const& view,
+    MPTIssue const& mptIssue,
+    AccountID const& account)
+{
+    auto maybeToken = findToken(view, mptIssue, account);
+
+    // Whatever reason why we could not find
+    if (!maybeToken)
+    {
+        // Convert tecNO_LINE to useful error
+        if (maybeToken.error() == tecNO_LINE)
+            return tecNO_AUTH;
+        // Note, error() is tesSUCCESS if no authorization was needed
+        return maybeToken.error();
+    }
+
+    auto sleToken = maybeToken->token;
+    auto sleIssuance = maybeToken->issuance;
 
     // mptoken must be authorized if issuance enabled requireAuth
     if (sleIssuance->getFieldU32(sfFlags) & lsfMPTRequireAuth &&