From d3b26f7077f58ebfcfccc5f0b16f8c29be5dc6b5 Mon Sep 17 00:00:00 2001
From: Matt Corallo <git@bluematt.me>
Date: Sat, 18 Aug 2012 23:38:28 -0400
Subject: [PATCH] Automatically add any matching outputs to a filter during
 matching.

---
 src/bloom.cpp | 20 ++++++++++++++++----
 src/bloom.h   |  3 ++-
 src/net.cpp   |  2 +-
 3 files changed, 19 insertions(+), 6 deletions(-)

diff --git a/src/bloom.cpp b/src/bloom.cpp
index 73b04aa3..e773bbbb 100644
--- a/src/bloom.cpp
+++ b/src/bloom.cpp
@@ -88,16 +88,21 @@ bool CBloomFilter::IsWithinSizeConstraints() const
     return vData.size() <= MAX_BLOOM_FILTER_SIZE && nHashFuncs <= MAX_HASH_FUNCS;
 }
 
-bool CBloomFilter::IsTransactionRelevantToFilter(const CTransaction& tx, const uint256& hash) const
+bool CBloomFilter::IsRelevantAndUpdate(const CTransaction& tx, const uint256& hash)
 {
+    bool fFound = false;
     // Match if the filter contains the hash of tx
     //  for finding tx when they appear in a block
     if (contains(hash))
-        return true;
+        fFound = true;
 
-    BOOST_FOREACH(const CTxOut& txout, tx.vout)
+    for (unsigned int i = 0; i < tx.vout.size(); i++)
     {
+        const CTxOut& txout = tx.vout[i];
         // Match if the filter contains any arbitrary script data element in any scriptPubKey in tx
+        // If this matches, also add the specific output that was matched.
+        // This means clients don't have to update the filter themselves when a new relevant tx 
+        // is discovered in order to find spending transactions, which avoids round-tripping and race conditions.
         CScript::const_iterator pc = txout.scriptPubKey.begin();
         vector<unsigned char> data;
         while (pc < txout.scriptPubKey.end())
@@ -106,10 +111,17 @@ bool CBloomFilter::IsTransactionRelevantToFilter(const CTransaction& tx, const u
             if (!txout.scriptPubKey.GetOp(pc, opcode, data))
                 break;
             if (data.size() != 0 && contains(data))
-                return true;
+            {
+                fFound = true;
+                insert(COutPoint(hash, i));
+                break;
+            }
         }
     }
 
+    if (fFound)
+        return true;
+
     BOOST_FOREACH(const CTxIn& txin, tx.vin)
     {
         // Match if the filter contains an outpoint tx spends
diff --git a/src/bloom.h b/src/bloom.h
index 335bb5e0..1a8a562d 100644
--- a/src/bloom.h
+++ b/src/bloom.h
@@ -64,7 +64,8 @@ public:
     // (catch a filter which was just deserialized which was too big)
     bool IsWithinSizeConstraints() const;
 
-    bool IsTransactionRelevantToFilter(const CTransaction& tx, const uint256& hash) const;
+    // Also adds any outputs which match the filter to the filter (to match their spending txes)
+    bool IsRelevantAndUpdate(const CTransaction& tx, const uint256& hash);
 };
 
 #endif /* BITCOIN_BLOOM_H */
diff --git a/src/net.cpp b/src/net.cpp
index aafc7206..e88efcd1 100644
--- a/src/net.cpp
+++ b/src/net.cpp
@@ -2034,7 +2034,7 @@ void RelayTransaction(const CTransaction& tx, const uint256& hash, const CDataSt
         LOCK(pnode->cs_filter);
         if (pnode->pfilter)
         {
-            if (pnode->pfilter->IsTransactionRelevantToFilter(tx, hash))
+            if (pnode->pfilter->IsRelevantAndUpdate(tx, hash))
                 pnode->PushInventory(inv);
         } else
             pnode->PushInventory(inv);