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import { BufferWriter } from "../../buffer.ts";import ServerCapabilities from "../../consttants/capabilities.ts";import { auth } from "../../auth/mysql_native_password.ts";import { HandshakeBody } from "../parsers/handshake.ts";import { Charset } from "../../consttants/charset.ts";
/** @ignore */export function buildAuth(  packet: HandshakeBody,  params: { username: string; password: string; db: string }): Uint8Array {  let clientParam: number =    (params.db ? ServerCapabilities.CLIENT_CONNECT_WITH_DB : 0) |    ServerCapabilities.CLIENT_PLUGIN_AUTH |    ServerCapabilities.CLIENT_LONG_PASSWORD |    ServerCapabilities.CLIENT_PROTOCOL_41 |    ServerCapabilities.CLIENT_TRANSACTIONS |    ServerCapabilities.CLIENT_MULTI_RESULTS |    ServerCapabilities.CLIENT_SECURE_CONNECTION;
  if (packet.serverCapabilities & ServerCapabilities.CLIENT_LONG_FLAG) {    clientParam |= ServerCapabilities.CLIENT_LONG_FLAG;  }  if (    packet.serverCapabilities &    ServerCapabilities.CLIENT_PLUGIN_AUTH_LENENC_CLIENT_DATA  ) {    clientParam |= ServerCapabilities.CLIENT_PLUGIN_AUTH_LENENC_CLIENT_DATA;  }  if (packet.serverCapabilities & ServerCapabilities.CLIENT_DEPRECATE_EOF) {    clientParam |= ServerCapabilities.CLIENT_DEPRECATE_EOF;  }  if (packet.serverCapabilities & ServerCapabilities.CLIENT_PLUGIN_AUTH) {    const writer = new BufferWriter(new Uint8Array(1000));    writer      .writeUint32(clientParam)      .writeUint32(265 * 256 * 256 - 1)      .write(Charset.UTF8_GENERAL_CI)      .skip(23)      .writeNullTerminatedString(params.username);    if (params.password) {      const authData = auth(params.password, packet.seed);      if (        clientParam &          ServerCapabilities.CLIENT_PLUGIN_AUTH_LENENC_CLIENT_DATA ||        clientParam & ServerCapabilities.CLIENT_SECURE_CONNECTION      ) {        // request lenenc-int length of auth-response and string[n] auth-response        writer.write(authData.length);        writer.writeBuffer(authData);      } else {        writer.writeBuffer(authData);        writer.write(0);      }    } else {      writer.write(0);    }    if (clientParam & ServerCapabilities.CLIENT_CONNECT_WITH_DB) {      writer.writeNullTerminatedString(params.db);    }    if (clientParam & ServerCapabilities.CLIENT_PLUGIN_AUTH) {      writer.writeNullTerminatedString(packet.authPluginName);    }    return writer.wroteData;  }}