ledger_request should confirm ledger is present (RIPD-1365):

The ledger_request RPC call, under some conditions, did not
actually check that the entire ledger was present in the
database, making it unsuitable for use in cases where the
database was believed to be incorrect or incomplete.
With this change, the full ledger will be checked for
integrity unless it has already recently been checked
(according to the InboundLedgers cache).

src/ripple/app/ledger/InboundLedger.h

@@ -65,7 +65,7 @@ class InboundLedger
     // Called when another attempt is made to fetch this same ledger
     void update (std::uint32_t seq);
 
-    std::shared_ptr<Ledger> const&
+    std::shared_ptr<Ledger const>
     getLedger() const
     {
         return mLedger;

src/ripple/app/ledger/InboundLedgers.h

@@ -41,7 +41,7 @@ class InboundLedgers
     // VFALCO TODO Should this be called findOrAdd ?
     //
     virtual
-    std::shared_ptr<Ledger>
+    std::shared_ptr<Ledger const>
     acquire (uint256 const& hash,
         std::uint32_t seq, InboundLedger::fcReason) = 0;
 

src/ripple/app/ledger/Ledger.cpp

@@ -705,7 +705,7 @@ bool Ledger::walkLedger (beast::Journal j) const
     return missingNodes1.empty () && missingNodes2.empty ();
 }
 
-bool Ledger::assertSane (beast::Journal ledgerJ)
+bool Ledger::assertSane (beast::Journal ledgerJ) const
 {
     if (info_.hash.isNonZero () &&
             info_.accountHash.isNonZero () &&

src/ripple/app/ledger/Ledger.h

@@ -303,7 +303,7 @@ class Ledger final
 
     bool walkLedger (beast::Journal j) const;
 
-    bool assertSane (beast::Journal ledgerJ);
+    bool assertSane (beast::Journal ledgerJ) const;
 
     void make_v2();
     void invariants() const;

src/ripple/app/ledger/impl/InboundLedgers.cpp

@@ -64,7 +64,7 @@ class InboundLedgersImp
     {
     }
 
-    std::shared_ptr<Ledger>
+    std::shared_ptr<Ledger const>
     acquire (
         uint256 const& hash,
         std::uint32_t seq,

src/ripple/app/main/Application.cpp

@@ -1543,7 +1543,7 @@ bool ApplicationImp::loadOldLedger (
 {
     try
     {
-        std::shared_ptr<Ledger> loadLedger, replayLedger;
+        std::shared_ptr<Ledger const> loadLedger, replayLedger;
 
         if (isFileName)
         {

src/ripple/rpc/handlers/LedgerRequest.cpp

@@ -23,6 +23,7 @@
 #include <ripple/app/ledger/LedgerMaster.h>
 #include <ripple/app/main/Application.h>
 #include <ripple/net/RPCErr.h>
+#include <ripple/resource/Fees.h>
 #include <ripple/rpc/Context.h>
 #include <ripple/protocol/ErrorCodes.h>
 #include <ripple/protocol/JsonFields.h>
@@ -38,6 +39,7 @@ Json::Value doLedgerRequest (RPC::Context& context)
 {
     auto const hasHash = context.params.isMember (jss::ledger_hash);
     auto const hasIndex = context.params.isMember (jss::ledger_index);
+    std::uint32_t ledgerIndex = 0;
 
     auto& ledgerMaster = context.app.getLedgerMaster();
     LedgerHash ledgerHash;
@@ -48,6 +50,8 @@ Json::Value doLedgerRequest (RPC::Context& context)
             "Exactly one of ledger_hash and ledger_index can be set.");
     }
 
+    context.loadType = Resource::feeHighBurdenRPC;
+
     if (hasHash)
     {
         auto const& jsonHash = context.params[jss::ledger_hash];
@@ -65,7 +69,7 @@ Json::Value doLedgerRequest (RPC::Context& context)
             RPC::Tuning::maxValidatedLedgerAge)
             return rpcError (rpcNO_CURRENT);
 
-        auto ledgerIndex = jsonIndex.asInt();
+        ledgerIndex = jsonIndex.asInt();
         auto ledger = ledgerMaster.getValidatedLedger();
 
         if (ledgerIndex >= ledger->info().seq)
@@ -118,28 +122,29 @@ Json::Value doLedgerRequest (RPC::Context& context)
         ledgerHash = neededHash ? *neededHash : zero; // kludge
     }
 
-    auto ledger = ledgerMaster.getLedgerByHash (ledgerHash);
+    // Try to get the desired ledger
+    // Verify all nodes even if we think we have it
+    auto ledger = context.app.getInboundLedgers().acquire (
+        ledgerHash, ledgerIndex, InboundLedger::fcGENERIC);
+
+    // In standalone mode, accept the ledger from the ledger cache
+    if (! ledger && context.app.config().standalone())
+        ledger = ledgerMaster.getLedgerByHash (ledgerHash);
+
     if (ledger)
     {
-        // We already have the ledger they want
+        // We already had the entire ledger verified/acquired
         Json::Value jvResult;
         jvResult[jss::ledger_index] = ledger->info().seq;
         addJson (jvResult, {*ledger, 0});
         return jvResult;
     }
-    else
-    {
-        // Try to get the desired ledger
-        if (auto il = context.app.getInboundLedgers ().acquire (
-                ledgerHash, 0, InboundLedger::fcGENERIC))
-            return getJson (LedgerFill (*il));
 
-        if (auto il = context.app.getInboundLedgers().find (ledgerHash))
-            return il->getJson (0);
+    if (auto il = context.app.getInboundLedgers().find (ledgerHash))
+        return il->getJson (0);
 
-        return RPC::make_error (
-            rpcNOT_READY, "findCreate failed to return an inbound ledger");
-    }
+    return RPC::make_error (
+        rpcNOT_READY, "findCreate failed to return an inbound ledger");
 }
 
 } // ripple