Merge pull request #7011

6531f17 Add mediantime field to getblock and getblockheader (Peter Todd)
7259769 Document new mediantime field in getblockchaininfo (Peter Todd)
c277a63 Clarify nLockTime-by-time comment in CheckFinalTx() (Peter Todd)
748321e Add mediantime field to getblockchaininfo RPC call (Peter Todd)

2 files changed, 11 insertions, 4 deletions

diff --git a/src/main.cpp b/src/main.cpp
index 8fb121c00d..439314f43b 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -670,10 +670,11 @@ bool CheckFinalTx(const CTransaction &tx, int flags)
     // IsFinalTx() with one more than chainActive.Height().
     const int nBlockHeight = chainActive.Height() + 1;
 
-    // Timestamps on the other hand don't get any special treatment,
-    // because we can't know what timestamp the next block will have,
-    // and there aren't timestamp applications where it matters.
-    // However this changes once median past time-locks are enforced:
+    // BIP113 will require that time-locked transactions have nLockTime set to
+    // less than the median time of the previous block they're contained in.
+    // When the next block is created its previous block will be the current
+    // chain tip, so we use that to calculate the median time passed to
+    // IsFinalTx() if LOCKTIME_MEDIAN_TIME_PAST is set.
     const int64_t nBlockTime = (flags & LOCKTIME_MEDIAN_TIME_PAST)
                              ? chainActive.Tip()->GetMedianTimePast()
                              : GetAdjustedTime();
diff --git a/src/rpcblockchain.cpp b/src/rpcblockchain.cpp
index 9c0e78f772..012370ed10 100644
--- a/src/rpcblockchain.cpp
+++ b/src/rpcblockchain.cpp
@@ -71,6 +71,7 @@ UniValue blockheaderToJSON(const CBlockIndex* blockindex)
     result.push_back(Pair("version", blockindex->nVersion));
     result.push_back(Pair("merkleroot", blockindex->hashMerkleRoot.GetHex()));
     result.push_back(Pair("time", (int64_t)blockindex->nTime));
+    result.push_back(Pair("mediantime", (int64_t)blockindex->GetMedianTimePast()));
     result.push_back(Pair("nonce", (uint64_t)blockindex->nNonce));
     result.push_back(Pair("bits", strprintf("%08x", blockindex->nBits)));
     result.push_back(Pair("difficulty", GetDifficulty(blockindex)));
@@ -111,6 +112,7 @@ UniValue blockToJSON(const CBlock& block, const CBlockIndex* blockindex, bool tx
     }
     result.push_back(Pair("tx", txs));
     result.push_back(Pair("time", block.GetBlockTime()));
+    result.push_back(Pair("mediantime", (int64_t)blockindex->GetMedianTimePast()));
     result.push_back(Pair("nonce", (uint64_t)block.nNonce));
     result.push_back(Pair("bits", strprintf("%08x", block.nBits)));
     result.push_back(Pair("difficulty", GetDifficulty(blockindex)));
@@ -313,6 +315,7 @@ UniValue getblockheader(const UniValue& params, bool fHelp)
             "  \"version\" : n,         (numeric) The block version\n"
             "  \"merkleroot\" : \"xxxx\", (string) The merkle root\n"
             "  \"time\" : ttt,          (numeric) The block time in seconds since epoch (Jan 1 1970 GMT)\n"
+            "  \"mediantime\" : ttt,    (numeric) The median block time in seconds since epoch (Jan 1 1970 GMT)\n"
             "  \"nonce\" : n,           (numeric) The nonce\n"
             "  \"bits\" : \"1d00ffff\", (string) The bits\n"
             "  \"difficulty\" : x.xxx,  (numeric) The difficulty\n"
@@ -374,6 +377,7 @@ UniValue getblock(const UniValue& params, bool fHelp)
             "     ,...\n"
             "  ],\n"
             "  \"time\" : ttt,          (numeric) The block time in seconds since epoch (Jan 1 1970 GMT)\n"
+            "  \"mediantime\" : ttt,    (numeric) The median block time in seconds since epoch (Jan 1 1970 GMT)\n"
             "  \"nonce\" : n,           (numeric) The nonce\n"
             "  \"bits\" : \"1d00ffff\", (string) The bits\n"
             "  \"difficulty\" : x.xxx,  (numeric) The difficulty\n"
@@ -608,6 +612,7 @@ UniValue getblockchaininfo(const UniValue& params, bool fHelp)
             "  \"headers\": xxxxxx,        (numeric) the current number of headers we have validated\n"
             "  \"bestblockhash\": \"...\", (string) the hash of the currently best block\n"
             "  \"difficulty\": xxxxxx,     (numeric) the current difficulty\n"
+            "  \"mediantime\": xxxxxx,     (numeric) median time for the current best block\n"
             "  \"verificationprogress\": xxxx, (numeric) estimate of verification progress [0..1]\n"
             "  \"chainwork\": \"xxxx\"     (string) total amount of work in active chain, in hexadecimal\n"
             "  \"pruned\": xx,             (boolean) if the blocks are subject to pruning\n"
@@ -639,6 +644,7 @@ UniValue getblockchaininfo(const UniValue& params, bool fHelp)
     obj.push_back(Pair("headers",               pindexBestHeader ? pindexBestHeader->nHeight : -1));
     obj.push_back(Pair("bestblockhash",         chainActive.Tip()->GetBlockHash().GetHex()));
     obj.push_back(Pair("difficulty",            (double)GetDifficulty()));
+    obj.push_back(Pair("mediantime",            (int64_t)chainActive.Tip()->GetMedianTimePast()));
     obj.push_back(Pair("verificationprogress",  Checkpoints::GuessVerificationProgress(Params().Checkpoints(), chainActive.Tip())));
     obj.push_back(Pair("chainwork",             chainActive.Tip()->nChainWork.GetHex()));
     obj.push_back(Pair("pruned",                fPruneMode));