Handle "conflicted" transactions properly

Extend CMerkleTx::GetDepthInMainChain with the concept of
a "conflicted" transaction-- a transaction generated by the wallet
that is not in the main chain or in the mempool, and, therefore,
will likely never be confirmed.

GetDepthInMainChain() now returns -1 for conflicted transactions
(0 for unconfirmed-but-in-the-mempool, and >1 for confirmed).

This makes getbalance, getbalance '*', and listunspent all agree when there are
mutated transactions in the wallet.

Before:
 listunspent: one 49BTC output
 getbalance: 96 BTC (change counted twice)
 getbalance '*': 46 BTC (spends counted twice)

After: all agree, 49 BTC available to spend.

1 files changed, 144 insertions, 0 deletions

diff --git a/qa/rpc-tests/txnmall.sh b/qa/rpc-tests/txnmall.sh
new file mode 100755
index 0000000000..7aca5f36df
--- /dev/null
+++ b/qa/rpc-tests/txnmall.sh
@@ -0,0 +1,144 @@
+#!/usr/bin/env bash
+
+# Test block generation and basic wallet sending
+
+if [ $# -lt 1 ]; then
+        echo "Usage: $0 path_to_binaries"
+        echo "e.g. $0 ../../src"
+        exit 1
+fi
+
+BITCOIND=${1}/bitcoind
+CLI=${1}/bitcoin-cli
+
+DIR="${BASH_SOURCE%/*}"
+SENDANDWAIT="${DIR}/send.sh"
+if [[ ! -d "$DIR" ]]; then DIR="$PWD"; fi
+. "$DIR/util.sh"
+
+D=$(mktemp -d test.XXXXX)
+
+# Two nodes; one will play the part of merchant, the
+# other an evil transaction-mutating miner.
+
+D1=${D}/node1
+CreateDataDir $D1 port=11000 rpcport=11001
+B1ARGS="-datadir=$D1 -debug"
+$BITCOIND $B1ARGS &
+B1PID=$!
+
+D2=${D}/node2
+CreateDataDir $D2 port=11010 rpcport=11011
+B2ARGS="-datadir=$D2 -debug"
+$BITCOIND $B2ARGS &
+B2PID=$!
+
+trap "kill -9 $B1PID $B2PID; rm -rf $D" EXIT
+
+# Wait until all four nodes are at the same block number
+function WaitBlocks {
+    while :
+    do
+        sleep 1
+        BLOCKS1=$( GetBlocks $B1ARGS )
+        BLOCKS2=$( GetBlocks $B2ARGS )
+        if (( $BLOCKS1 == $BLOCKS2 ))
+        then
+            break
+        fi
+    done
+}
+
+# Wait until node has $N peers
+function WaitPeers {
+    while :
+    do
+        PEERS=$( $CLI $1 getconnectioncount )
+        if (( "$PEERS" == $2 ))
+        then
+            break
+        fi
+        sleep 1
+    done
+}
+
+# Start with B2 connected to B1:
+$CLI $B2ARGS addnode 127.0.0.1:11000 onetry
+WaitPeers "$B1ARGS" 1
+
+# 1 block, 50 XBT each == 50 XBT
+$CLI $B1ARGS setgenerate true 1
+
+WaitBlocks
+# 100 blocks, 0 mature == 0 XBT
+$CLI $B2ARGS setgenerate true 100
+WaitBlocks
+
+CheckBalance $B1ARGS 50
+CheckBalance $B2ARGS 0
+
+# restart B2 with no connection
+$CLI $B2ARGS stop > /dev/null 2>&1
+wait $B2PID
+$BITCOIND $B2ARGS &
+B2PID=$!
+
+B2ADDRESS=$( $CLI $B2ARGS getnewaddress )
+
+# Have B1 create two transactions; second will
+# spend change from first, since B1 starts with only a single
+# 50 bitcoin output:
+TXID1=$( $CLI $B1ARGS sendtoaddress $B2ADDRESS 1.0 )
+TXID2=$( $CLI $B1ARGS sendtoaddress $B2ADDRESS 2.0 )
+
+# Mutate TXID1 and add it to B2's memory pool:
+RAWTX1=$( $CLI $B1ARGS getrawtransaction $TXID1 )
+RAWTX2=$( $CLI $B1ARGS getrawtransaction $TXID2 )
+# ... mutate RAWTX1:
+# RAWTX1 is hex-encoded, serialized transaction. So each
+# byte is two characters; we'll prepend the first
+# "push" in the scriptsig with OP_PUSHDATA1 (0x4c),
+# and add one to the length of the signature.
+# Fields are fixed; from the beginning:
+# 4-byte version
+# 1-byte varint number-of inputs (one in this case)
+# 32-byte previous txid
+# 4-byte previous output
+# 1-byte varint length-of-scriptsig
+# 1-byte PUSH this many bytes onto stack
+#  ... etc
+# So: to mutate, we want to get byte 41 (hex characters 82-83),
+# increment it, and insert 0x4c after it.
+L=${RAWTX1:82:2}
+NEWLEN=$( printf "%x" $(( 16#$L + 1 )) )
+MUTATEDTX1=${RAWTX1:0:82}${NEWLEN}4c${RAWTX1:84}
+# ... give mutated tx1 to B2:
+MUTATEDTXID=$( $CLI $B2ARGS sendrawtransaction $MUTATEDTX1 )
+
+echo "TXID1: " $TXID1
+echo "Mutated: " $MUTATEDTXID
+
+# Re-connect nodes, and have B2 mine a block
+$CLI $B2ARGS addnode 127.0.0.1:11000 onetry
+WaitPeers "$B1ARGS" 1
+
+$CLI $B2ARGS setgenerate true 1
+WaitBlocks
+
+$CLI $B2ARGS stop > /dev/null 2>&1
+wait $B2PID
+$CLI $B1ARGS stop > /dev/null 2>&1
+wait $B1PID
+
+trap "" EXIT
+
+echo "Done, bitcoind's shut down. To rerun/poke around:"
+echo "${1}/bitcoind -datadir=$D1 -daemon"
+echo "${1}/bitcoind -datadir=$D2 -daemon -connect=127.0.0.1:11000"
+echo "To cleanup:"
+echo "killall bitcoind; rm -rf test.*"
+exit 0
+
+echo "Tests successful, cleaning up"
+rm -rf $D
+exit 0