From c3af143133a7447f7399c61bea67e60cd37d2e97 Mon Sep 17 00:00:00 2001
From: Pieter Wuille <pieter.wuille@gmail.com>
Date: Wed, 8 Jun 2016 14:48:03 +0200
Subject: [PATCH] Remove unreliable lookup-tx-by-utxo functionality

---
 doc/REST-interface.md      |  2 +-
 src/main.cpp               | 27 +--------------------------
 src/main.h                 |  4 ++--
 src/rest.cpp               |  2 +-
 src/rpc/rawtransaction.cpp |  6 +++---
 5 files changed, 8 insertions(+), 33 deletions(-)

diff --git a/doc/REST-interface.md b/doc/REST-interface.md
index bf669235e38a..9ec93fe4866d 100644
--- a/doc/REST-interface.md
+++ b/doc/REST-interface.md
@@ -11,7 +11,7 @@ Supported API
 
 Given a transaction hash: returns a transaction in binary, hex-encoded binary, or JSON formats.
 
-For full TX query capability, one must enable the transaction index via "txindex=1" command line / configuration option.
+This works only on unconfirmed transaction unless the transaction index is enabled via "txindex=1" command line / configuration option.
 
 ####Blocks
 `GET /rest/block/<BLOCK-HASH>.<bin|hex|json>`
diff --git a/src/main.cpp b/src/main.cpp
index bd028fefba80..61b898620042 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -1440,7 +1440,7 @@ bool AcceptToMemoryPool(CTxMemPool& pool, CValidationState &state, const CTransa
 }
 
 /** Return transaction in tx, and if it was found inside a block, its hash is placed in hashBlock */
-bool GetTransaction(const uint256 &hash, CTransaction &txOut, const Consensus::Params& consensusParams, uint256 &hashBlock, bool fAllowSlow)
+bool GetTransaction(const uint256 &hash, CTransaction &txOut, const Consensus::Params& consensusParams, uint256 &hashBlock)
 {
     CBlockIndex *pindexSlow = NULL;
 
@@ -1474,31 +1474,6 @@ bool GetTransaction(const uint256 &hash, CTransaction &txOut, const Consensus::P
         }
     }
 
-    if (fAllowSlow) { // use coin database to locate block that contains transaction, and scan it
-        int nHeight = -1;
-        {
-            const CCoinsViewCache& view = *pcoinsTip;
-            const CCoins* coins = view.AccessCoins(hash);
-            if (coins)
-                nHeight = coins->nHeight;
-        }
-        if (nHeight > 0)
-            pindexSlow = chainActive[nHeight];
-    }
-
-    if (pindexSlow) {
-        CBlock block;
-        if (ReadBlockFromDisk(block, pindexSlow, consensusParams)) {
-            BOOST_FOREACH(const CTransaction &tx, block.vtx) {
-                if (tx.GetHash() == hash) {
-                    txOut = tx;
-                    hashBlock = pindexSlow->GetBlockHash();
-                    return true;
-                }
-            }
-        }
-    }
-
     return false;
 }
 
diff --git a/src/main.h b/src/main.h
index 4e93c084f417..f5744aae7d44 100644
--- a/src/main.h
+++ b/src/main.h
@@ -254,8 +254,8 @@ bool IsInitialBlockDownload();
  * This function only returns the highest priority warning of the set selected by strFor.
  */
 std::string GetWarnings(const std::string& strFor);
-/** Retrieve a transaction (from memory pool, or from disk, if possible) */
-bool GetTransaction(const uint256 &hash, CTransaction &tx, const Consensus::Params& params, uint256 &hashBlock, bool fAllowSlow = false);
+/** Retrieve a transaction (from memory pool, or from txindex) */
+bool GetTransaction(const uint256 &hash, CTransaction &tx, const Consensus::Params& params, uint256 &hashBlock);
 /** Find the best known block, and make it the tip of the block chain */
 bool ActivateBestChain(CValidationState& state, const CChainParams& chainparams, const CBlock* pblock = NULL);
 CAmount GetBlockSubsidy(int nHeight, const Consensus::Params& consensusParams);
diff --git a/src/rest.cpp b/src/rest.cpp
index 2dff8d7daddf..1b14b081447d 100644
--- a/src/rest.cpp
+++ b/src/rest.cpp
@@ -364,7 +364,7 @@ static bool rest_tx(HTTPRequest* req, const std::string& strURIPart)
 
     CTransaction tx;
     uint256 hashBlock = uint256();
-    if (!GetTransaction(hash, tx, Params().GetConsensus(), hashBlock, true))
+    if (!GetTransaction(hash, tx, Params().GetConsensus(), hashBlock))
         return RESTERR(req, HTTP_NOT_FOUND, hashStr + " not found");
 
     CDataStream ssTx(SER_NETWORK, PROTOCOL_VERSION);
diff --git a/src/rpc/rawtransaction.cpp b/src/rpc/rawtransaction.cpp
index 4517ffcbbc5c..89498aa67733 100644
--- a/src/rpc/rawtransaction.cpp
+++ b/src/rpc/rawtransaction.cpp
@@ -188,8 +188,8 @@ UniValue getrawtransaction(const UniValue& params, bool fHelp)
 
     CTransaction tx;
     uint256 hashBlock;
-    if (!GetTransaction(hash, tx, Params().GetConsensus(), hashBlock, true))
-        throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "No information available about transaction");
+    if (!GetTransaction(hash, tx, Params().GetConsensus(), hashBlock))
+        throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "No information available about transaction. Use `gettransaction` for wallet transactions, or enable -txindex to use getrawtransaction on confirmed transactions.");
 
     string strHex = EncodeHexTx(tx);
 
@@ -258,7 +258,7 @@ UniValue gettxoutproof(const UniValue& params, bool fHelp)
     if (pblockindex == NULL)
     {
         CTransaction tx;
-        if (!GetTransaction(oneTxid, tx, Params().GetConsensus(), hashBlock, false) || hashBlock.IsNull())
+        if (!GetTransaction(oneTxid, tx, Params().GetConsensus(), hashBlock) || hashBlock.IsNull())
             throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Transaction not yet in block");
         if (!mapBlockIndex.count(hashBlock))
             throw JSONRPCError(RPC_INTERNAL_ERROR, "Transaction index corrupt");