aboutsummaryrefslogtreecommitdiff
path: root/src/script
diff options
context:
space:
mode:
Diffstat (limited to 'src/script')
-rw-r--r--src/script/interpreter.cpp55
-rw-r--r--src/script/interpreter.h10
-rw-r--r--src/script/script.cpp31
-rw-r--r--src/script/script.h35
-rw-r--r--src/script/standard.h1
5 files changed, 84 insertions, 48 deletions
diff --git a/src/script/interpreter.cpp b/src/script/interpreter.cpp
index cd73b88210..11c909472a 100644
--- a/src/script/interpreter.cpp
+++ b/src/script/interpreter.cpp
@@ -157,6 +157,29 @@ bool static CheckPubKeyEncoding(const valtype &vchSig, unsigned int flags) {
return true;
}
+bool static CheckMinimalPush(const valtype& data, opcodetype opcode) {
+ if (data.size() == 0) {
+ // Could have used OP_0.
+ return opcode == OP_0;
+ } else if (data.size() == 1 && data[0] >= 1 && data[0] <= 16) {
+ // Could have used OP_1 .. OP_16.
+ return opcode == OP_1 + (data[0] - 1);
+ } else if (data.size() == 1 && data[0] == 0x81) {
+ // Could have used OP_1NEGATE.
+ return opcode == OP_1NEGATE;
+ } else if (data.size() <= 75) {
+ // Could have used a direct push (opcode indicating number of bytes pushed + those bytes).
+ return opcode == data.size();
+ } else if (data.size() <= 255) {
+ // Could have used OP_PUSHDATA.
+ return opcode == OP_PUSHDATA1;
+ } else if (data.size() <= 65535) {
+ // Could have used OP_PUSHDATA2.
+ return opcode == OP_PUSHDATA2;
+ }
+ return true;
+}
+
bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, unsigned int flags, const BaseSignatureChecker& checker)
{
CScript::const_iterator pc = script.begin();
@@ -169,6 +192,7 @@ bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, un
if (script.size() > 10000)
return false;
int nOpCount = 0;
+ bool fRequireMinimal = (flags & SCRIPT_VERIFY_MINIMALDATA) != 0;
try
{
@@ -205,9 +229,12 @@ bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, un
opcode == OP_RSHIFT)
return false; // Disabled opcodes.
- if (fExec && 0 <= opcode && opcode <= OP_PUSHDATA4)
+ if (fExec && 0 <= opcode && opcode <= OP_PUSHDATA4) {
+ if (fRequireMinimal && !CheckMinimalPush(vchPushValue, opcode)) {
+ return false;
+ }
stack.push_back(vchPushValue);
- else if (fExec || (OP_IF <= opcode && opcode <= OP_ENDIF))
+ } else if (fExec || (OP_IF <= opcode && opcode <= OP_ENDIF))
switch (opcode)
{
//
@@ -234,6 +261,8 @@ bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, un
// ( -- value)
CScriptNum bn((int)opcode - (int)(OP_1 - 1));
stack.push_back(bn.getvch());
+ // The result of these opcodes should always be the minimal way to push the data
+ // they push, so no need for a CheckMinimalPush here.
}
break;
@@ -458,7 +487,7 @@ bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, un
// (xn ... x2 x1 x0 n - ... x2 x1 x0 xn)
if (stack.size() < 2)
return false;
- int n = CScriptNum(stacktop(-1)).getint();
+ int n = CScriptNum(stacktop(-1), fRequireMinimal).getint();
popstack(stack);
if (n < 0 || n >= (int)stack.size())
return false;
@@ -557,7 +586,7 @@ bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, un
// (in -- out)
if (stack.size() < 1)
return false;
- CScriptNum bn(stacktop(-1));
+ CScriptNum bn(stacktop(-1), fRequireMinimal);
switch (opcode)
{
case OP_1ADD: bn += bnOne; break;
@@ -590,8 +619,8 @@ bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, un
// (x1 x2 -- out)
if (stack.size() < 2)
return false;
- CScriptNum bn1(stacktop(-2));
- CScriptNum bn2(stacktop(-1));
+ CScriptNum bn1(stacktop(-2), fRequireMinimal);
+ CScriptNum bn2(stacktop(-1), fRequireMinimal);
CScriptNum bn(0);
switch (opcode)
{
@@ -635,9 +664,9 @@ bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, un
// (x min max -- out)
if (stack.size() < 3)
return false;
- CScriptNum bn1(stacktop(-3));
- CScriptNum bn2(stacktop(-2));
- CScriptNum bn3(stacktop(-1));
+ CScriptNum bn1(stacktop(-3), fRequireMinimal);
+ CScriptNum bn2(stacktop(-2), fRequireMinimal);
+ CScriptNum bn3(stacktop(-1), fRequireMinimal);
bool fValue = (bn2 <= bn1 && bn1 < bn3);
popstack(stack);
popstack(stack);
@@ -727,7 +756,7 @@ bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, un
if ((int)stack.size() < i)
return false;
- int nKeysCount = CScriptNum(stacktop(-i)).getint();
+ int nKeysCount = CScriptNum(stacktop(-i), fRequireMinimal).getint();
if (nKeysCount < 0 || nKeysCount > 20)
return false;
nOpCount += nKeysCount;
@@ -738,7 +767,7 @@ bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, un
if ((int)stack.size() < i)
return false;
- int nSigsCount = CScriptNum(stacktop(-i)).getint();
+ int nSigsCount = CScriptNum(stacktop(-i), fRequireMinimal).getint();
if (nSigsCount < 0 || nSigsCount > nKeysCount)
return false;
int isig = ++i;
@@ -980,6 +1009,10 @@ bool SignatureChecker::CheckSig(const vector<unsigned char>& vchSigIn, const vec
bool VerifyScript(const CScript& scriptSig, const CScript& scriptPubKey, unsigned int flags, const BaseSignatureChecker& checker)
{
+ if ((flags & SCRIPT_VERIFY_SIGPUSHONLY) != 0 && !scriptSig.IsPushOnly()) {
+ return false;
+ }
+
vector<vector<unsigned char> > stack, stackCopy;
if (!EvalScript(stack, scriptSig, flags, checker))
return false;
diff --git a/src/script/interpreter.h b/src/script/interpreter.h
index de5ce2ced1..5133c80aab 100644
--- a/src/script/interpreter.h
+++ b/src/script/interpreter.h
@@ -46,6 +46,16 @@ enum
// verify dummy stack item consumed by CHECKMULTISIG is of zero-length (softfork safe, BIP62 rule 7).
SCRIPT_VERIFY_NULLDUMMY = (1U << 4),
+
+ // Using a non-push operator in the scriptSig causes script failure (softfork safe, 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)
};
uint256 SignatureHash(const CScript &scriptCode, const CTransaction& txTo, unsigned int nIn, int nHashType);
diff --git a/src/script/script.cpp b/src/script/script.cpp
index 3e19d0c2bf..b879d72d6b 100644
--- a/src/script/script.cpp
+++ b/src/script/script.cpp
@@ -12,7 +12,7 @@ namespace {
inline std::string ValueString(const std::vector<unsigned char>& vch)
{
if (vch.size() <= 4)
- return strprintf("%d", CScriptNum(vch).getint());
+ return strprintf("%d", CScriptNum(vch, false).getint());
else
return HexStr(vch);
}
@@ -230,7 +230,7 @@ bool CScript::IsPushOnly() const
return false;
// Note that IsPushOnly() *does* consider OP_RESERVED to be a
// push-type opcode, however execution of OP_RESERVED fails, so
- // it's not relevant to P2SH as the scriptSig would fail prior to
+ // it's not relevant to P2SH/BIP62 as the scriptSig would fail prior to
// the P2SH special validation code being executed.
if (opcode > OP_16)
return false;
@@ -238,33 +238,6 @@ bool CScript::IsPushOnly() const
return true;
}
-bool CScript::HasCanonicalPushes() const
-{
- const_iterator pc = begin();
- while (pc < end())
- {
- opcodetype opcode;
- std::vector<unsigned char> data;
- if (!GetOp(pc, opcode, data))
- return false;
- if (opcode > OP_16)
- continue;
- if (opcode < OP_PUSHDATA1 && opcode > OP_0 && (data.size() == 1 && data[0] <= 16))
- // Could have used an OP_n code, rather than a 1-byte push.
- return false;
- if (opcode == OP_PUSHDATA1 && data.size() < OP_PUSHDATA1)
- // Could have used a normal n-byte push, rather than OP_PUSHDATA1.
- return false;
- if (opcode == OP_PUSHDATA2 && data.size() <= 0xFF)
- // Could have used an OP_PUSHDATA1.
- return false;
- if (opcode == OP_PUSHDATA4 && data.size() <= 0xFFFF)
- // Could have used an OP_PUSHDATA2.
- return false;
- }
- return true;
-}
-
std::string CScript::ToString() const
{
std::string str;
diff --git a/src/script/script.h b/src/script/script.h
index d450db5cad..05f2e7e3a9 100644
--- a/src/script/script.h
+++ b/src/script/script.h
@@ -192,10 +192,29 @@ public:
m_value = n;
}
- explicit CScriptNum(const std::vector<unsigned char>& vch)
+ explicit CScriptNum(const std::vector<unsigned char>& vch, bool fRequireMinimal)
{
- if (vch.size() > nMaxNumSize)
- throw scriptnum_error("CScriptNum(const std::vector<unsigned char>&) : overflow");
+ if (vch.size() > nMaxNumSize) {
+ throw scriptnum_error("script number overflow");
+ }
+ if (fRequireMinimal && vch.size() > 0) {
+ // Check that the number is encoded with the minimum possible
+ // number of bytes.
+ //
+ // If the most-significant-byte - excluding the sign bit - is zero
+ // then we're not minimal. Note how this test also rejects the
+ // negative-zero encoding, 0x80.
+ if ((vch.back() & 0x7f) == 0) {
+ // One exception: if there's more than one byte and the most
+ // significant bit of the second-most-significant-byte is set
+ // it would conflict with the sign bit. An example of this case
+ // is +-255, which encode to 0xff00 and 0xff80 respectively.
+ // (big-endian).
+ if (vch.size() <= 1 || (vch[vch.size() - 2] & 0x80) == 0) {
+ throw scriptnum_error("non-minimally encoded script number");
+ }
+ }
+ }
m_value = set_vch(vch);
}
@@ -319,7 +338,6 @@ private:
int64_t m_value;
};
-
/** Serialized script, used inside transaction inputs and outputs */
class CScript : public std::vector<unsigned char>
{
@@ -330,6 +348,10 @@ protected:
{
push_back(n + (OP_1 - 1));
}
+ else if (n == 0)
+ {
+ push_back(OP_0);
+ }
else
{
*this << CScriptNum::serialize(n);
@@ -551,12 +573,9 @@ public:
bool IsPayToScriptHash() const;
- // Called by IsStandardTx and P2SH VerifyScript (which makes it consensus-critical).
+ // Called by IsStandardTx and P2SH/BIP62 VerifyScript (which makes it consensus-critical).
bool IsPushOnly() const;
- // Called by IsStandardTx.
- bool HasCanonicalPushes() const;
-
// Returns whether the script is guaranteed to fail at execution,
// regardless of the initial stack. This allows outputs to be pruned
// instantly when entering the UTXO set.
diff --git a/src/script/standard.h b/src/script/standard.h
index 961b214c89..248b941a64 100644
--- a/src/script/standard.h
+++ b/src/script/standard.h
@@ -41,6 +41,7 @@ static const unsigned int MANDATORY_SCRIPT_VERIFY_FLAGS = SCRIPT_VERIFY_P2SH;
// blocks and we must accept those blocks.
static const unsigned int STANDARD_SCRIPT_VERIFY_FLAGS = MANDATORY_SCRIPT_VERIFY_FLAGS |
SCRIPT_VERIFY_STRICTENC |
+ SCRIPT_VERIFY_MINIMALDATA |
SCRIPT_VERIFY_NULLDUMMY;
// For convenience, standard but not mandatory verify flags.
generated by cgit v1.2.3 (git 2.26.2) at 2024-11-01 08:27:44 +0000