From 79417ac59a037bc39a11a6a53512db02e9a1b858 Mon Sep 17 00:00:00 2001
From: JoelKatz <DavidJoelSchwartz@GMail.com>
Date: Tue, 3 Mar 2015 14:01:38 -0800
Subject: [PATCH] Limit passes in the payment engine to prevent endless
 looping:

This adds a limit of 1,000 passes to the payment engine. It protects against
possible cases where the execution of a pass fails to exhaust the liquidity
that made the pass possible or cases where two passes alternate providing
liquidity for each other.
---
 src/ripple/app/paths/RippleCalc.cpp | 14 +++++++++++++-
 src/ripple/app/paths/Tuning.h       |  1 +
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/src/ripple/app/paths/RippleCalc.cpp b/src/ripple/app/paths/RippleCalc.cpp
index 0c2e8e71d..446521539 100644
--- a/src/ripple/app/paths/RippleCalc.cpp
+++ b/src/ripple/app/paths/RippleCalc.cpp
@@ -18,6 +18,7 @@
 //==============================================================================
 
 #include <BeastConfig.h>
+#include <ripple/app/paths/Tuning.h>
 #include <ripple/app/paths/RippleCalc.h>
 #include <ripple/app/paths/cursor/PathCursor.h>
 #include <ripple/basics/Log.h>
@@ -295,11 +296,12 @@ TER RippleCalc::rippleCalculate ()
             }
         }
 
+        ++iPass;
         if (ShouldLog (lsDEBUG, RippleCalc))
         {
             WriteLog (lsDEBUG, RippleCalc)
                 << "rippleCalc: Summary:"
-                << " Pass: " << ++iPass
+                << " Pass: " << iPass
                 << " Dry: " << iDry
                 << " Paths: " << pathStateList_.size ();
             for (auto pathState: pathStateList_)
@@ -374,6 +376,16 @@ TER RippleCalc::rippleCalculate ()
                 mumSource_.insert (
                     pathState->reverse().begin (), pathState->reverse().end ());
 
+                if (iPass >= PAYMENT_MAX_LOOPS)
+                {
+                    // This payment is taking too many passes
+
+                    WriteLog (lsERROR, RippleCalc)
+                       << "rippleCalc: pass limit";
+
+                    resultCode = telFAILED_PROCESSING;
+                }
+
             }
             else if (!inputFlags.partialPaymentAllowed)
             {
diff --git a/src/ripple/app/paths/Tuning.h b/src/ripple/app/paths/Tuning.h
index d786502df..d498459ad 100644
--- a/src/ripple/app/paths/Tuning.h
+++ b/src/ripple/app/paths/Tuning.h
@@ -24,6 +24,7 @@ namespace ripple {
 
 int const CALC_NODE_DELIVER_MAX_LOOPS = 40;
 int const NODE_ADVANCE_MAX_LOOPS = 100;
+int const PAYMENT_MAX_LOOPS = 1000;
 int const PATHFINDER_HIGH_PRIORITY = 100000;
 int const PATHFINDER_MAX_PATHS = 50;
 int const PATHFINDER_MAX_COMPLETE_PATHS = 1000;