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authorWladimir J. van der Laan <laanwj@gmail.com>2017-12-12 10:10:14 +0100
committerWladimir J. van der Laan <laanwj@gmail.com>2017-12-12 10:11:00 +0100
commitc0902624b0ec6f5fff29eb6e922c58816f395dc8 (patch)
tree55b0aeead40d1bc462db9b313948cb805abbfa3e /src/script/interpreter.h
parent0e722e8879a8e1eebe02fd14c70c39346c79f95d (diff)
parent01013f5d2fbe3fa86565c927bf7bb8ec0f525073 (diff)
Merge #10699: Make all script validation flags backward compatible
01013f5 Simplify tx validation tests (Pieter Wuille) 2dd6f80 Add a test that all flags are softforks (Pieter Wuille) 2851b77 Make all script verification flags softforks (Pieter Wuille) Pull request description: This change makes `SCRIPT_VERIFY_UPGRADABLE_NOPS` not apply to `OP_CHECKLOCKTIMEVERIFY` and `OP_CHECKSEQUENCEVERIFY`. This is a no-op as `UPGRADABLE_NOPS` is only set for mempool transactions, and those always have `SCRIPT_VERIFY_CHECKLOCKTIMEVERIFY` and `SCRIPT_VERIFY_CHECKSEQUENCEVERIFY` set as well. The advantage is that setting more flags now always results in a reduction in acceptable scripts (=softfork). This results in a nice and testable property for validation, for which a new test is added. This also means that the introduction of a new definition for a NOP or witness version will likely need the following procedure (example OP_NOP8 here) * Remove OP_NOP8 from being affected by `SCRIPT_VERIFY_DISCOURAGE_UPGRADABLE_NOPS`. * Add a `SCRIPT_VERIFY_DISCOURAGE_NOP8`, which only applies to `OP_NOP8`. * Add a `SCRIPT_VERIFY_NOP8` which implements the new consensus logic. * Before activation, add `SCRIPT_VERIFY_DISCOURAGE_NOP8` to the mempool flags. * After activation, add `SCRIPT_VERIFY_NOP8` to both the mempool and consensus flags. Tree-SHA512: d3b4538986ecf646aac9dba13a8d89318baf9e308e258547ca3b99e7c0509747f323edac6b1fea4e87e7d3c01b71193794b41679ae4f86f6e11ed6be3fd62c72
Diffstat (limited to 'src/script/interpreter.h')
-rw-r--r--src/script/interpreter.h23
1 files changed, 14 insertions, 9 deletions
diff --git a/src/script/interpreter.h b/src/script/interpreter.h
index 2eae68179e..83a96739b1 100644
--- a/src/script/interpreter.h
+++ b/src/script/interpreter.h
@@ -27,37 +27,40 @@ enum
SIGHASH_ANYONECANPAY = 0x80,
};
-/** Script verification flags */
+/** Script verification flags.
+ *
+ * All flags are intended to be soft forks: the set of acceptable scripts under
+ * flags (A | B) is a subset of the acceptable scripts under flag (A).
+ */
enum
{
SCRIPT_VERIFY_NONE = 0,
- // Evaluate P2SH subscripts (softfork safe, BIP16).
+ // Evaluate P2SH subscripts (BIP16).
SCRIPT_VERIFY_P2SH = (1U << 0),
// Passing a non-strict-DER signature or one with undefined hashtype to a checksig operation causes script failure.
// Evaluating a pubkey that is not (0x04 + 64 bytes) or (0x02 or 0x03 + 32 bytes) by checksig causes script failure.
- // (softfork safe, but not used or intended as a consensus rule).
+ // (not used or intended as a consensus rule).
SCRIPT_VERIFY_STRICTENC = (1U << 1),
- // Passing a non-strict-DER signature to a checksig operation causes script failure (softfork safe, BIP62 rule 1)
+ // Passing a non-strict-DER signature to a checksig operation causes script failure (BIP62 rule 1)
SCRIPT_VERIFY_DERSIG = (1U << 2),
// Passing a non-strict-DER signature or one with S > order/2 to a checksig operation causes script failure
- // (softfork safe, BIP62 rule 5).
+ // (BIP62 rule 5).
SCRIPT_VERIFY_LOW_S = (1U << 3),
- // verify dummy stack item consumed by CHECKMULTISIG is of zero-length (softfork safe, BIP62 rule 7).
+ // verify dummy stack item consumed by CHECKMULTISIG is of zero-length (BIP62 rule 7).
SCRIPT_VERIFY_NULLDUMMY = (1U << 4),
- // Using a non-push operator in the scriptSig causes script failure (softfork safe, BIP62 rule 2).
+ // Using a non-push operator in the scriptSig causes script failure (BIP62 rule 2).
SCRIPT_VERIFY_SIGPUSHONLY = (1U << 5),
// Require minimal encodings for all push operations (OP_0... OP_16, OP_1NEGATE where possible, direct
// pushes up to 75 bytes, OP_PUSHDATA up to 255 bytes, OP_PUSHDATA2 for anything larger). Evaluating
// any other push causes the script to fail (BIP62 rule 3).
// In addition, whenever a stack element is interpreted as a number, it must be of minimal length (BIP62 rule 4).
- // (softfork safe)
SCRIPT_VERIFY_MINIMALDATA = (1U << 6),
// Discourage use of NOPs reserved for upgrades (NOP1-10)
@@ -68,12 +71,14 @@ enum
// discouraged NOPs fails the script. This verification flag will never be
// a mandatory flag applied to scripts in a block. NOPs that are not
// executed, e.g. within an unexecuted IF ENDIF block, are *not* rejected.
+ // NOPs that have associated forks to give them new meaning (CLTV, CSV)
+ // are not subject to this rule.
SCRIPT_VERIFY_DISCOURAGE_UPGRADABLE_NOPS = (1U << 7),
// Require that only a single stack element remains after evaluation. This changes the success criterion from
// "At least one stack element must remain, and when interpreted as a boolean, it must be true" to
// "Exactly one stack element must remain, and when interpreted as a boolean, it must be true".
- // (softfork safe, BIP62 rule 6)
+ // (BIP62 rule 6)
// Note: CLEANSTACK should never be used without P2SH or WITNESS.
SCRIPT_VERIFY_CLEANSTACK = (1U << 8),