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-rw-r--r--src/policy/policy.cpp39
1 files changed, 38 insertions, 1 deletions
diff --git a/src/policy/policy.cpp b/src/policy/policy.cpp
index 6f8b6c2953..2b19a6714b 100644
--- a/src/policy/policy.cpp
+++ b/src/policy/policy.cpp
@@ -15,6 +15,43 @@
#include <boost/foreach.hpp>
+CAmount GetDustThreshold(const CTxOut& txout, const CFeeRate& dustRelayFee)
+{
+ // "Dust" is defined in terms of dustRelayFee,
+ // which has units satoshis-per-kilobyte.
+ // If you'd pay more than 1/3 in fees
+ // to spend something, then we consider it dust.
+ // A typical spendable non-segwit txout is 34 bytes big, and will
+ // need a CTxIn of at least 148 bytes to spend:
+ // so dust is a spendable txout less than
+ // 546*dustRelayFee/1000 (in satoshis).
+ // A typical spendable segwit txout is 31 bytes big, and will
+ // need a CTxIn of at least 67 bytes to spend:
+ // so dust is a spendable txout less than
+ // 294*dustRelayFee/1000 (in satoshis).
+ if (txout.scriptPubKey.IsUnspendable())
+ return 0;
+
+ size_t nSize = GetSerializeSize(txout, SER_DISK, 0);
+ int witnessversion = 0;
+ std::vector<unsigned char> witnessprogram;
+
+ if (txout.scriptPubKey.IsWitnessProgram(witnessversion, witnessprogram)) {
+ // sum the sizes of the parts of a transaction input
+ // with 75% segwit discount applied to the script size.
+ nSize += (32 + 4 + 1 + (107 / WITNESS_SCALE_FACTOR) + 4);
+ } else {
+ nSize += (32 + 4 + 1 + 107 + 4); // the 148 mentioned above
+ }
+
+ return 3 * dustRelayFee.GetFee(nSize);
+}
+
+bool IsDust(const CTxOut& txout, const CFeeRate& dustRelayFee)
+{
+ return (txout.nValue < GetDustThreshold(txout, dustRelayFee));
+}
+
/**
* Check transaction inputs to mitigate two
* potential denial-of-service attacks:
@@ -106,7 +143,7 @@ bool IsStandardTx(const CTransaction& tx, std::string& reason, const bool witnes
else if ((whichType == TX_MULTISIG) && (!fIsBareMultisigStd)) {
reason = "bare-multisig";
return false;
- } else if (txout.IsDust(dustRelayFee)) {
+ } else if (IsDust(txout, ::dustRelayFee)) {
reason = "dust";
return false;
}