From 6bc061a549e3581a0bf8c7e113a0d7c961f1b17e Mon Sep 17 00:00:00 2001
From: Sun Yimin <emmansun@users.noreply.github.com>
Date: Wed, 13 Dec 2023 14:19:31 +0800
Subject: [PATCH] cipher: reduce duplicate code

---
 cipher/bc.go     | 22 +++-------------------
 cipher/ecb.go    |  9 +++++----
 cipher/ofbnlf.go | 23 +++--------------------
 3 files changed, 11 insertions(+), 43 deletions(-)

diff --git a/cipher/bc.go b/cipher/bc.go
index 629d466..86b85e1 100644
--- a/cipher/bc.go
+++ b/cipher/bc.go
@@ -5,7 +5,6 @@ package cipher
 import (
 	_cipher "crypto/cipher"
 
-	"github.com/emmansun/gmsm/internal/alias"
 	"github.com/emmansun/gmsm/internal/subtle"
 )
 
@@ -51,15 +50,7 @@ func NewBCEncrypter(b _cipher.Block, iv []byte) _cipher.BlockMode {
 func (x *bcEncrypter) BlockSize() int { return x.blockSize }
 
 func (x *bcEncrypter) CryptBlocks(dst, src []byte) {
-	if len(src)%x.blockSize != 0 {
-		panic("cipher: input not full blocks")
-	}
-	if len(dst) < len(src) {
-		panic("cipher: output smaller than input")
-	}
-	if alias.InexactOverlap(dst[:len(src)], src) {
-		panic("cipher: invalid buffer overlap")
-	}
+	validate(x.blockSize, dst, src)
 
 	iv := x.iv
 
@@ -110,15 +101,8 @@ func NewBCDecrypter(b _cipher.Block, iv []byte) _cipher.BlockMode {
 func (x *bcDecrypter) BlockSize() int { return x.blockSize }
 
 func (x *bcDecrypter) CryptBlocks(dst, src []byte) {
-	if len(src)%x.blockSize != 0 {
-		panic("cipher: input not full blocks")
-	}
-	if len(dst) < len(src) {
-		panic("cipher: output smaller than input")
-	}
-	if alias.InexactOverlap(dst[:len(src)], src) {
-		panic("cipher: invalid buffer overlap")
-	}
+	validate(x.blockSize, dst, src)
+
 	if len(src) == 0 {
 		return
 	}
diff --git a/cipher/ecb.go b/cipher/ecb.go
index 45c3b70..94acdb8 100644
--- a/cipher/ecb.go
+++ b/cipher/ecb.go
@@ -21,8 +21,8 @@ func newECB(b goCipher.Block) *ecb {
 	}
 }
 
-func (x *ecb) validate(dst, src []byte) {
-	if len(src)%x.blockSize != 0 {
+func validate(size int, dst, src []byte) {
+	if len(src)%size != 0 {
 		panic("cipher: input not full blocks")
 	}
 	if len(dst) < len(src) {
@@ -55,7 +55,7 @@ func NewECBEncrypter(b goCipher.Block) goCipher.BlockMode {
 func (x *ecbEncrypter) BlockSize() int { return x.blockSize }
 
 func (x *ecbEncrypter) CryptBlocks(dst, src []byte) {
-	(*ecb)(x).validate(dst, src)
+	validate(x.blockSize, dst, src)
 
 	for len(src) > 0 {
 		x.b.Encrypt(dst[:x.blockSize], src[:x.blockSize])
@@ -86,11 +86,12 @@ func NewECBDecrypter(b goCipher.Block) goCipher.BlockMode {
 func (x *ecbDecrypter) BlockSize() int { return x.blockSize }
 
 func (x *ecbDecrypter) CryptBlocks(dst, src []byte) {
-	(*ecb)(x).validate(dst, src)
+	validate(x.blockSize, dst, src)
 
 	if len(src) == 0 {
 		return
 	}
+
 	for len(src) > 0 {
 		x.b.Decrypt(dst[:x.blockSize], src[:x.blockSize])
 		src = src[x.blockSize:]
diff --git a/cipher/ofbnlf.go b/cipher/ofbnlf.go
index 9011be6..f571907 100644
--- a/cipher/ofbnlf.go
+++ b/cipher/ofbnlf.go
@@ -6,8 +6,6 @@ package cipher
 import (
 	_cipher "crypto/cipher"
 	"errors"
-
-	"github.com/emmansun/gmsm/internal/alias"
 )
 
 type ofbnlf struct {
@@ -51,15 +49,7 @@ func NewOFBNLFEncrypter(cipherFunc CipherCreator, key, iv []byte) (_cipher.Block
 func (x *ofbnlfEncrypter) BlockSize() int { return x.blockSize }
 
 func (x *ofbnlfEncrypter) CryptBlocks(dst, src []byte) {
-	if len(src)%x.blockSize != 0 {
-		panic("cipher: input not full blocks")
-	}
-	if len(dst) < len(src) {
-		panic("cipher: output smaller than input")
-	}
-	if alias.InexactOverlap(dst[:len(src)], src) {
-		panic("cipher: invalid buffer overlap")
-	}
+	validate(x.blockSize, dst, src)
 
 	iv := x.iv
 	k := make([]byte, x.blockSize)
@@ -104,15 +94,8 @@ func NewOFBNLFDecrypter(cipherFunc CipherCreator, key, iv []byte) (_cipher.Block
 func (x *ofbnlfDecrypter) BlockSize() int { return x.blockSize }
 
 func (x *ofbnlfDecrypter) CryptBlocks(dst, src []byte) {
-	if len(src)%x.blockSize != 0 {
-		panic("cipher: input not full blocks")
-	}
-	if len(dst) < len(src) {
-		panic("cipher: output smaller than input")
-	}
-	if alias.InexactOverlap(dst[:len(src)], src) {
-		panic("cipher: invalid buffer overlap")
-	}
+	validate(x.blockSize, dst, src)
+
 	if len(src) == 0 {
 		return
 	}