Add offset and length params

mirai-core/src/commonMain/kotlin/net.mamoe.mirai/utils/cryptor/Decrypters.kt

@@ -3,7 +3,10 @@ package net.mamoe.mirai.utils.cryptor
 import kotlinx.io.core.BytePacketBuilder
 import kotlinx.io.core.ByteReadPacket
 import kotlinx.io.core.IoBuffer
+import kotlinx.io.pool.useInstance
+import net.mamoe.mirai.utils.io.ByteArrayPool
 import net.mamoe.mirai.utils.io.encryptAndWrite
+import net.mamoe.mirai.utils.io.toReadPacket
 
 
 /**
@@ -11,7 +14,7 @@ import net.mamoe.mirai.utils.io.encryptAndWrite
  */
 interface DecrypterByteArray : Decrypter {
     val value: ByteArray
-    override fun decrypt(input: ByteReadPacket): ByteReadPacket = input.decryptBy(value)
+    override fun decrypt(input: ByteReadPacket, offset: Int, length: Int): ByteReadPacket = input.decryptBy(value, offset, length)
 }
 
 /**
@@ -19,33 +22,41 @@ interface DecrypterByteArray : Decrypter {
  */
 interface DecrypterIoBuffer : Decrypter {
     val value: IoBuffer
-    override fun decrypt(input: ByteReadPacket): ByteReadPacket = input.decryptBy(value)
+    override fun decrypt(input: ByteReadPacket, offset: Int, length: Int): ByteReadPacket = input.decryptBy(value, offset, length)
 }
 
 /**
  * 连接在一起的解密器
  */
-inline class LinkedDecrypter(inline val block: (ByteReadPacket) -> ByteReadPacket) : Decrypter {
-    override fun decrypt(input: ByteReadPacket): ByteReadPacket = block(input)
+inline class LinkedDecrypter(inline val block: (input: ByteReadPacket, offset: Int, length: Int) -> ByteReadPacket) : Decrypter {
+    override fun decrypt(input: ByteReadPacket, offset: Int, length: Int): ByteReadPacket = block(input, offset, length)
 }
 
-object NoDecrypter : Decrypter,
-    DecrypterType<NoDecrypter> {
-    override fun decrypt(input: ByteReadPacket): ByteReadPacket = input
+object NoDecrypter : Decrypter, DecrypterType<NoDecrypter> {
+    override fun decrypt(input: ByteReadPacket, offset: Int, length: Int): ByteReadPacket {
+        if (offset == 0 && length == input.remaining.toInt()) {
+            return input
+        }
+
+        ByteArrayPool.useInstance { buffer ->
+            input.readFully(buffer, offset, length)
+            return buffer.toReadPacket()
+        }
+    }
 }
 
 /**
  * 解密器
- */ 
+ */
 interface Decrypter {
-    fun decrypt(input: ByteReadPacket): ByteReadPacket
+    fun decrypt(input: ByteReadPacket, offset: Int = 0, length: Int = (input.remaining - offset).toInt()): ByteReadPacket
     /**
      * 连接后将会先用 this 解密, 再用 [another] 解密
      */
     operator fun plus(another: Decrypter): Decrypter =
-        LinkedDecrypter { another.decrypt(this.decrypt(it)) }
+        LinkedDecrypter { input: ByteReadPacket, offset: Int, length: Int -> another.decrypt(this.decrypt(input, offset, length)) }
 }
- 
+
 interface DecrypterType<D : Decrypter>
 
 inline fun BytePacketBuilder.encryptAndWrite(key: DecrypterByteArray, encoder: BytePacketBuilder.() -> Unit) =

mirai-core/src/commonMain/kotlin/net.mamoe.mirai/utils/cryptor/TEA.kt

@@ -94,9 +94,9 @@ fun IoBuffer.decryptBy(key: ByteArray, offset: Int = 0, length: Int = readRemain
 
 // region ByteReadPacket extension
 
-fun ByteReadPacket.decryptBy(key: ByteArray): ByteReadPacket = decryptAsByteArray(key) { data -> ByteReadPacket(data, 0) }
+fun ByteReadPacket.decryptBy(key: ByteArray, offset: Int = 0, length: Int = key.size - offset): ByteReadPacket = decryptAsByteArray(key) { data -> ByteReadPacket(data, offset, length) }
 
-fun ByteReadPacket.decryptBy(key: IoBuffer): ByteReadPacket = decryptAsByteArray(key) { data -> ByteReadPacket(data, 0) }
+fun ByteReadPacket.decryptBy(key: IoBuffer, offset: Int = 0, length: Int = key.readRemaining - offset): ByteReadPacket = decryptAsByteArray(key) { data -> ByteReadPacket(data,  offset, length) }
 
 inline fun <R> ByteReadPacket.decryptAsByteArray(key: ByteArray, consumer: (ByteArray) -> R): R =
     ByteArrayPool.useInstance {

mirai-core/src/commonMain/kotlin/net.mamoe.mirai/utils/io/InputUtils.kt

@@ -52,8 +52,6 @@ fun Input.readIP(): String = buildString(4 + 3) {
     }
 }
 
-fun Input.readPacket(length: Int): ByteReadPacket = this.readBytes(length).toReadPacket()
-
 fun Input.readQQ(): Long = this.readUInt().toLong()
 fun Input.readGroup(): Long = this.readUInt().toLong()
 fun Input.readGroupId(): GroupId = this.readUInt().toLong().groupId()