Backend half

SerpentRace_Backend/node_modules/mariadb/lib/io/compression-input-stream.js

@@ -0,0 +1,142 @@
+//  SPDX-License-Identifier: LGPL-2.1-or-later
+//  Copyright (c) 2015-2024 MariaDB Corporation Ab
+
+'use strict';
+
+const ZLib = require('zlib');
+const Utils = require('../misc/utils');
+
+/**
+ * MySQL packet parser
+ * see : https://mariadb.com/kb/en/library/0-packet/
+ */
+class CompressionInputStream {
+  constructor(reader, receiveQueue, opts, info) {
+    this.reader = reader;
+    this.receiveQueue = receiveQueue;
+    this.info = info;
+    this.opts = opts;
+    this.header = Buffer.allocUnsafe(7);
+    this.headerLen = 0;
+    this.compressPacketLen = null;
+    this.packetLen = null;
+    this.remainingLen = null;
+
+    this.parts = null;
+    this.partsTotalLen = 0;
+  }
+
+  receivePacket(chunk) {
+    let cmd = this.currentCmd();
+    if (this.opts.debugCompress) {
+      this.opts.logger.network(
+        `<== conn:${this.info.threadId ? this.info.threadId : -1} ${
+          cmd
+            ? cmd.onPacketReceive
+              ? cmd.constructor.name + '.' + cmd.onPacketReceive.name
+              : cmd.constructor.name
+            : 'no command'
+        } (compress)\n${Utils.log(this.opts, chunk, 0, chunk.length, this.header)}`
+      );
+    }
+    if (cmd) cmd.compressSequenceNo = this.header[3];
+    const unCompressLen = this.header[4] | (this.header[5] << 8) | (this.header[6] << 16);
+    if (unCompressLen === 0) {
+      this.reader.onData(chunk);
+    } else {
+      //use synchronous inflating, to ensure FIFO packet order
+      const unCompressChunk = ZLib.inflateSync(chunk);
+      this.reader.onData(unCompressChunk);
+    }
+  }
+
+  currentCmd() {
+    let cmd;
+    while ((cmd = this.receiveQueue.peek())) {
+      if (cmd.onPacketReceive) return cmd;
+      this.receiveQueue.shift();
+    }
+    return null;
+  }
+
+  resetHeader() {
+    this.remainingLen = null;
+    this.headerLen = 0;
+  }
+
+  onData(chunk) {
+    let pos = 0;
+    let length;
+    const chunkLen = chunk.length;
+
+    do {
+      if (this.remainingLen) {
+        length = this.remainingLen;
+      } else if (this.headerLen === 0 && chunkLen - pos >= 7) {
+        this.header[0] = chunk[pos];
+        this.header[1] = chunk[pos + 1];
+        this.header[2] = chunk[pos + 2];
+        this.header[3] = chunk[pos + 3];
+        this.header[4] = chunk[pos + 4];
+        this.header[5] = chunk[pos + 5];
+        this.header[6] = chunk[pos + 6];
+        this.headerLen = 7;
+        pos += 7;
+        this.compressPacketLen = this.header[0] + (this.header[1] << 8) + (this.header[2] << 16);
+        this.packetLen = this.header[4] | (this.header[5] << 8) | (this.header[6] << 16);
+        if (this.packetLen === 0) this.packetLen = this.compressPacketLen;
+        length = this.compressPacketLen;
+      } else {
+        length = null;
+        while (chunkLen - pos > 0) {
+          this.header[this.headerLen++] = chunk[pos++];
+          if (this.headerLen === 7) {
+            this.compressPacketLen = this.header[0] + (this.header[1] << 8) + (this.header[2] << 16);
+            this.packetLen = this.header[4] | (this.header[5] << 8) | (this.header[6] << 16);
+            if (this.packetLen === 0) this.packetLen = this.compressPacketLen;
+            length = this.compressPacketLen;
+            break;
+          }
+        }
+      }
+
+      if (length) {
+        if (chunkLen - pos >= length) {
+          const buf = chunk.subarray(pos, pos + length);
+          pos += length;
+          if (this.parts) {
+            this.parts.push(buf);
+            this.partsTotalLen += length;
+
+            if (this.compressPacketLen < 0xffffff) {
+              let buf = Buffer.concat(this.parts, this.partsTotalLen);
+              this.parts = null;
+              this.receivePacket(buf);
+            }
+          } else {
+            if (this.compressPacketLen < 0xffffff) {
+              this.receivePacket(buf);
+            } else {
+              this.parts = [buf];
+              this.partsTotalLen = length;
+            }
+          }
+          this.resetHeader();
+        } else {
+          const buf = chunk.subarray(pos, chunkLen);
+          if (!this.parts) {
+            this.parts = [buf];
+            this.partsTotalLen = chunkLen - pos;
+          } else {
+            this.parts.push(buf);
+            this.partsTotalLen += chunkLen - pos;
+          }
+          this.remainingLen = length - (chunkLen - pos);
+          return;
+        }
+      }
+    } while (pos < chunkLen);
+  }
+}
+
+module.exports = CompressionInputStream;