Merge #7543: [0.12] Backport BIP9, BIP68 and BIP112 with softfork

640666b [qa] rpc-tests: Properly use integers, floats (BtcDrak)
c270b62 Fix comments in tests (BtcDrak)
caf1381 Add bip68-sequence.py to extended rpc tests (BtcDrak)
26e9a05 Test of BIP9 fork activation of mtp, csv, sequence_lock (NicolasDorier)
3a99feb Add RPC test for BIP 68/112/113 soft fork. (Alex Morcos)
159ee3d Policy: allow transaction version 2 relay policy. (BtcDrak)
9713ed3 Soft fork logic for BIP68 (BtcDrak)
648be9b Soft fork logic for BIP113 (BtcDrak)
ee40924 Add CHECKSEQUENCEVERIFY softfork through BIP9 (Pieter Wuille)
6ff0b9f RPC test for BIP9 warning logic (Suhas Daftuar)
0710b30 Test versionbits deployments (Suhas Daftuar)
8ebc6f2 Add testing of ComputeBlockVersion (Suhas Daftuar)
0bdaacd Softfork status report in RPC (Pieter Wuille)
5f90d4e Versionbits tests (Pieter Wuille)
6f83cf2 BIP9 Implementation (Pieter Wuille)
ade85e1 Add LockPoints (Alex Morcos)
c8d309e Code style fix. (BtcDrak)
6170506 Separate CheckLockTime() and CheckSequence() logic (BtcDrak)
c0c5e09 BIP112: Implement CHECKSEQUENCEVERIFY (Mark Friedenbach)
197c376 fix sdaftuar's nits again (Alex Morcos)
0a79c04 Bug fix to RPC test (Alex Morcos)
0d09af7 Add RPC test exercising BIP68 (mempool only) (Suhas Daftuar)
15ba08c Implement SequenceLocks functions (Alex Morcos)

1 files changed, 37 insertions, 8 deletions

diff --git a/src/primitives/transaction.h b/src/primitives/transaction.h
index 8bd6d00e2e..9f7d6f3943 100644
--- a/src/primitives/transaction.h
+++ b/src/primitives/transaction.h
@@ -61,13 +61,40 @@ public:
     CScript scriptSig;
     uint32_t nSequence;
 
+    /* Setting nSequence to this value for every input in a transaction
+     * disables nLockTime. */
+    static const uint32_t SEQUENCE_FINAL = 0xffffffff;
+
+    /* Below flags apply in the context of BIP 68*/
+    /* If this flag set, CTxIn::nSequence is NOT interpreted as a
+     * relative lock-time. */
+    static const uint32_t SEQUENCE_LOCKTIME_DISABLE_FLAG = (1 << 31);
+
+    /* If CTxIn::nSequence encodes a relative lock-time and this flag
+     * is set, the relative lock-time has units of 512 seconds,
+     * otherwise it specifies blocks with a granularity of 1. */
+    static const uint32_t SEQUENCE_LOCKTIME_TYPE_FLAG = (1 << 22);
+
+    /* If CTxIn::nSequence encodes a relative lock-time, this mask is
+     * applied to extract that lock-time from the sequence field. */
+    static const uint32_t SEQUENCE_LOCKTIME_MASK = 0x0000ffff;
+
+    /* In order to use the same number of bits to encode roughly the
+     * same wall-clock duration, and because blocks are naturally
+     * limited to occur every 600s on average, the minimum granularity
+     * for time-based relative lock-time is fixed at 512 seconds.
+     * Converting from CTxIn::nSequence to seconds is performed by
+     * multiplying by 512 = 2^9, or equivalently shifting up by
+     * 9 bits. */
+    static const int SEQUENCE_LOCKTIME_GRANULARITY = 9;
+
     CTxIn()
     {
-        nSequence = std::numeric_limits<unsigned int>::max();
+        nSequence = SEQUENCE_FINAL;
     }
 
-    explicit CTxIn(COutPoint prevoutIn, CScript scriptSigIn=CScript(), uint32_t nSequenceIn=std::numeric_limits<unsigned int>::max());
-    CTxIn(uint256 hashPrevTx, uint32_t nOut, CScript scriptSigIn=CScript(), uint32_t nSequenceIn=std::numeric_limits<uint32_t>::max());
+    explicit CTxIn(COutPoint prevoutIn, CScript scriptSigIn=CScript(), uint32_t nSequenceIn=SEQUENCE_FINAL);
+    CTxIn(uint256 hashPrevTx, uint32_t nOut, CScript scriptSigIn=CScript(), uint32_t nSequenceIn=SEQUENCE_FINAL);
 
     ADD_SERIALIZE_METHODS;
 
@@ -78,11 +105,6 @@ public:
         READWRITE(nSequence);
     }
 
-    bool IsFinal() const
-    {
-        return (nSequence == std::numeric_limits<uint32_t>::max());
-    }
-
     friend bool operator==(const CTxIn& a, const CTxIn& b)
     {
         return (a.prevout   == b.prevout &&
@@ -184,8 +206,15 @@ private:
     void UpdateHash() const;
 
 public:
+    // Default transaction version.
     static const int32_t CURRENT_VERSION=1;
 
+    // Changing the default transaction version requires a two step process: first
+    // adapting relay policy by bumping MAX_STANDARD_VERSION, and then later date
+    // bumping the default CURRENT_VERSION at which point both CURRENT_VERSION and
+    // MAX_STANDARD_VERSION will be equal.
+    static const int32_t MAX_STANDARD_VERSION=2;
+
     // The local variables are made const to prevent unintended modification
     // without updating the cached hash value. However, CTransaction is not
     // actually immutable; deserialization and assignment are implemented,