From 29c9bc27c85d10d8ff048c08055404ef8cfbec24 Mon Sep 17 00:00:00 2001
From: Donald Adu-Poku <donald.adu@gmail.com>
Date: Wed, 20 Jun 2018 19:32:36 +0000
Subject: [PATCH] blockchain: remove impossible to hit ErrInvalidSSRtxInput.

ErrInvalidSSRtxInput's triggering condition is a subset of the checks IsSSRtx performs on a transaction. Since IsSSRtx is the first to evaluate a tx in CheckTransactionInputs that should be enough.
---
 blockchain/error.go      |  5 -----
 blockchain/error_test.go |  1 -
 blockchain/validate.go   | 21 ---------------------
 3 files changed, 27 deletions(-)

diff --git a/blockchain/error.go b/blockchain/error.go
index ff7d050697..b86d7ddd87 100644
--- a/blockchain/error.go
+++ b/blockchain/error.go
@@ -348,10 +348,6 @@ const (
 	// be OP_SS* tagged, but it must be P2PKH or P2SH.
 	ErrSStxInScrType
 
-	// ErrInvalidSSRtxInput indicates that the input for the SSRtx was not from
-	// an SStx.
-	ErrInvalidSSRtxInput
-
 	// ErrSSRtxPayeesMismatch means that the number of payees in an SSRtx was
 	// not the same as the number of payees in the outputs of the input SStx.
 	ErrSSRtxPayeesMismatch
@@ -532,7 +528,6 @@ var errorCodeStrings = map[ErrorCode]string{
 	ErrSSGenSubsidy:           "ErrSSGenSubsidy",
 	ErrSStxInImmature:         "ErrSStxInImmature",
 	ErrSStxInScrType:          "ErrSStxInScrType",
-	ErrInvalidSSRtxInput:      "ErrInvalidSSRtxInput",
 	ErrSSRtxPayeesMismatch:    "ErrSSRtxPayeesMismatch",
 	ErrSSRtxPayees:            "ErrSSRtxPayees",
 	ErrTxSStxOutSpend:         "ErrTxSStxOutSpend",
diff --git a/blockchain/error_test.go b/blockchain/error_test.go
index 266e52f29b..82953f5917 100644
--- a/blockchain/error_test.go
+++ b/blockchain/error_test.go
@@ -84,7 +84,6 @@ func TestErrorCodeStringer(t *testing.T) {
 		{ErrSSGenSubsidy, "ErrSSGenSubsidy"},
 		{ErrSStxInImmature, "ErrSStxInImmature"},
 		{ErrSStxInScrType, "ErrSStxInScrType"},
-		{ErrInvalidSSRtxInput, "ErrInvalidSSRtxInput"},
 		{ErrSSRtxPayeesMismatch, "ErrSSRtxPayeesMismatch"},
 		{ErrSSRtxPayees, "ErrSSRtxPayees"},
 		{ErrTxSStxOutSpend, "ErrTxSStxOutSpend"},
diff --git a/blockchain/validate.go b/blockchain/validate.go
index 6b80142cec..936a4ea19f 100644
--- a/blockchain/validate.go
+++ b/blockchain/validate.go
@@ -1529,15 +1529,6 @@ func CheckTransactionInputs(subsidyCache *SubsidyCache, tx *dcrutil.Tx, txHeight
 			return 0, ruleError(ErrMissingTxOut, str)
 		}
 
-		// While we're here, double check to make sure that the input
-		// is from an SStx.  By doing so, you also ensure the first
-		// output is OP_SSTX tagged.
-		if utxoEntrySstx.TransactionType() != stake.TxTypeSStx {
-			errStr := fmt.Sprintf("Input transaction %v for SSRtx"+
-				" %v was not an SStx tx", txHash, sstxHash)
-			return 0, ruleError(ErrInvalidSSRtxInput, errStr)
-		}
-
 		minOutsSStx := ConvertUtxosToMinimalOutputs(utxoEntrySstx)
 		sstxPayTypes, sstxPkhs, sstxAmts, _, sstxRules, sstxLimits :=
 			stake.SStxStakeOutputInfo(minOutsSStx)
@@ -1581,18 +1572,6 @@ func CheckTransactionInputs(subsidyCache *SubsidyCache, tx *dcrutil.Tx, txHeight
 			return 0, ruleError(ErrSSRtxPayees, errStr)
 		}
 
-		// 2. Check to make sure that the second input was an OP_SSTX
-		//    tagged output from the referenced SStx.
-		if txscript.GetScriptClass(utxoEntrySstx.ScriptVersionByIndex(0),
-			utxoEntrySstx.PkScriptByIndex(0)) !=
-			txscript.StakeSubmissionTy {
-			errStr := fmt.Sprintf("First SStx output in SStx %v "+
-				"referenced by SSGen %v should have been "+
-				"OP_SSTX tagged, but it was not", sstxHash,
-				txHash)
-			return 0, ruleError(ErrInvalidSSRtxInput, errStr)
-		}
-
 		// 3. Check to ensure that ticket maturity number of blocks
 		//    have passed between the block the SSRtx plans to go into
 		//    and the block in which the SStx was originally found in.