connection.ts

/*!
 * Substantial parts adapted from https://github.com/brianc/node-postgres
 * which is licensed as follows:
 *
 * The MIT License (MIT)
 *
 * Copyright (c) 2010 - 2019 Brian Carlson
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * 'Software'), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
 * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

import { BufReader, BufWriter, Hash } from "./deps.ts";
import { PacketWriter } from "./packet_writer.ts";
import { hashMd5Password, readUInt32BE } from "./utils.ts";
import { PacketReader } from "./packet_reader.ts";
import { QueryConfig, QueryResult, Query } from "./query.ts";
import { parseError } from "./error.ts";
import { ConnectionParams } from "./connection_params.ts";

export enum Format {
  TEXT = 0,
  BINARY = 1,
}

enum TransactionStatus {
  Idle = "I",
  IdleInTransaction = "T",
  InFailedTransaction = "E",
}

export class Message {
  public reader: PacketReader;

  constructor(
    public type: string,
    public byteCount: number,
    public body: Uint8Array,
  ) {
    this.reader = new PacketReader(body);
  }
}

export class Column {
  constructor(
    public name: string,
    public tableOid: number,
    public index: number,
    public typeOid: number,
    public columnLength: number,
    public typeModifier: number,
    public format: Format,
  ) {}
}

export class RowDescription {
  constructor(public columnCount: number, public columns: Column[]) {}
}

export class Connection {
  private conn!: Deno.Conn;

  private bufReader!: BufReader;
  private bufWriter!: BufWriter;
  private packetWriter!: PacketWriter;
  private decoder: TextDecoder = new TextDecoder();
  private encoder: TextEncoder = new TextEncoder();

  private _transactionStatus?: TransactionStatus;
  private _pid?: number;
  private _secretKey?: number;
  private _parameters: { [key: string]: string } = {};

  constructor(private connParams: ConnectionParams) {}

  /** Read single message sent by backend */
  async readMessage(): Promise<Message> {
    // TODO: reuse buffer instead of allocating new ones each for each read
    const header = new Uint8Array(5);
    await this.bufReader.readFull(header);
    const msgType = this.decoder.decode(header.slice(0, 1));
    const msgLength = readUInt32BE(header, 1) - 4;
    const msgBody = new Uint8Array(msgLength);
    await this.bufReader.readFull(msgBody);

    return new Message(msgType, msgLength, msgBody);
  }

  private async _sendStartupMessage() {
    const writer = this.packetWriter;
    writer.clear();
    // protocol version - 3.0, written as
    writer.addInt16(3).addInt16(0);
    const connParams = this.connParams;
    // TODO: recognize other parameters
    writer.addCString("user").addCString(connParams.user);
    writer.addCString("database").addCString(connParams.database);
    writer.addCString("application_name").addCString(
      connParams.applicationName,
    );

    // eplicitly set utf-8 encoding
    writer.addCString("client_encoding").addCString("'utf-8'");
    // terminator after all parameters were writter
    writer.addCString("");

    const bodyBuffer = writer.flush();
    const bodyLength = bodyBuffer.length + 4;

    writer.clear();

    const finalBuffer = writer
      .addInt32(bodyLength)
      .add(bodyBuffer)
      .join();

    await this.bufWriter.write(finalBuffer);
  }

  async startup() {
    const { port, hostname } = this.connParams;
    this.conn = await Deno.connect({ port, hostname });

    this.bufReader = new BufReader(this.conn);
    this.bufWriter = new BufWriter(this.conn);
    this.packetWriter = new PacketWriter();

    await this._sendStartupMessage();
    await this.bufWriter.flush();

    let msg: Message;

    msg = await this.readMessage();
    await this.handleAuth(msg);

    while (true) {
      msg = await this.readMessage();
      switch (msg.type) {
        // backend key data
        case "K":
          this._processBackendKeyData(msg);
          break;
        // parameter status
        case "S":
          this._processParameterStatus(msg);
          break;
        // ready for query
        case "Z":
          this._processReadyForQuery(msg);
          return;
        default:
          throw new Error(`Unknown response for startup: ${msg.type}`);
      }
    }
  }

  async handleAuth(msg: Message) {
    const code = msg.reader.readInt32();
    switch (code) {
      case 0:
        // pass
        break;
      case 3:
        // cleartext password
        await this._authCleartext();
        await this._readAuthResponse();
        break;
      case 5:
        // md5 password
        const salt = msg.reader.readBytes(4);
        await this._authMd5(salt);
        await this._readAuthResponse();
        break;
      default:
        throw new Error(`Unknown auth message code ${code}`);
    }
  }

  private async _readAuthResponse() {
    const msg = await this.readMessage();

    if (msg.type === "E") {
      throw parseError(msg);
    } else if (msg.type !== "R") {
      throw new Error(`Unexpected auth response: ${msg.type}.`);
    }

    const responseCode = msg.reader.readInt32();
    if (responseCode !== 0) {
      throw new Error(`Unexpected auth response code: ${responseCode}.`);
    }
  }

  private async _authCleartext() {
    this.packetWriter.clear();
    const password = this.connParams.password || "";
    const buffer = this.packetWriter.addCString(password).flush(0x70);

    await this.bufWriter.write(buffer);
    await this.bufWriter.flush();
  }

  private async _authMd5(salt: Uint8Array) {
    this.packetWriter.clear();

    if (!this.connParams.password) {
      throw new Error("Auth Error: attempting MD5 auth with password unset");
    }

    const password = hashMd5Password(
      this.connParams.password,
      this.connParams.user,
      salt,
    );
    const buffer = this.packetWriter.addCString(password).flush(0x70);

    await this.bufWriter.write(buffer);
    await this.bufWriter.flush();
  }

  private _processBackendKeyData(msg: Message) {
    this._pid = msg.reader.readInt32();
    this._secretKey = msg.reader.readInt32();
  }

  private _processParameterStatus(msg: Message) {
    // TODO: should we save all parameters?
    const key = msg.reader.readCString();
    const value = msg.reader.readCString();
    this._parameters[key] = value;
  }

  private _processReadyForQuery(msg: Message) {
    const txStatus = msg.reader.readByte();
    this._transactionStatus = String.fromCharCode(
      txStatus,
    ) as TransactionStatus;
  }

  private async _readReadyForQuery() {
    const msg = await this.readMessage();

    if (msg.type !== "Z") {
      throw new Error(
        `Unexpected message type: ${msg.type}, expected "Z" (ReadyForQuery)`,
      );
    }

    this._processReadyForQuery(msg);
  }

  private async _simpleQuery(query: Query): Promise<QueryResult> {
    this.packetWriter.clear();

    const buffer = this.packetWriter.addCString(query.text).flush(0x51);

    await this.bufWriter.write(buffer);
    await this.bufWriter.flush();

    const result = query.result;

    let msg: Message;

    msg = await this.readMessage();

    switch (msg.type) {
      // row description
      case "T":
        result.handleRowDescription(this._processRowDescription(msg));
        break;
      // no data
      case "n":
        break;
      // error response
      case "E":
        await this._processError(msg);
        break;
      // notice response
      case "N":
        // TODO:
        console.log("TODO: handle notice");
        break;
      // command complete
      // TODO: this is duplicated in next loop
      case "C":
        const commandTag = this._readCommandTag(msg);
        result.handleCommandComplete(commandTag);
        result.done();
        break;
      default:
        throw new Error(`Unexpected frame: ${msg.type}`);
    }

    while (true) {
      msg = await this.readMessage();
      switch (msg.type) {
        // data row
        case "D":
          // this is actually packet read
          const foo = this._readDataRow(msg);
          result.handleDataRow(foo);
          break;
        // command complete
        case "C":
          const commandTag = this._readCommandTag(msg);
          result.handleCommandComplete(commandTag);
          result.done();
          break;
        // ready for query
        case "Z":
          this._processReadyForQuery(msg);
          return result;
        // error response
        case "E":
          await this._processError(msg);
          break;
        default:
          throw new Error(`Unexpected frame: ${msg.type}`);
      }
    }
  }

  async _sendPrepareMessage(query: Query) {
    this.packetWriter.clear();

    const buffer = this.packetWriter
      .addCString("") // TODO: handle named queries (config.name)
      .addCString(query.text)
      .addInt16(0)
      .flush(0x50);
    await this.bufWriter.write(buffer);
  }

  async _sendBindMessage(query: Query) {
    this.packetWriter.clear();

    const hasBinaryArgs = query.args.reduce((prev, curr) => {
      return prev || curr instanceof Uint8Array;
    }, false);

    // bind statement
    this.packetWriter.clear();
    this.packetWriter
      .addCString("") // TODO: unnamed portal
      .addCString(""); // TODO: unnamed prepared statement

    if (hasBinaryArgs) {
      this.packetWriter.addInt16(query.args.length);

      query.args.forEach((arg) => {
        this.packetWriter.addInt16(arg instanceof Uint8Array ? 1 : 0);
      });
    } else {
      this.packetWriter.addInt16(0);
    }

    this.packetWriter.addInt16(query.args.length);

    query.args.forEach((arg) => {
      if (arg === null || typeof arg === "undefined") {
        this.packetWriter.addInt32(-1);
      } else if (arg instanceof Uint8Array) {
        this.packetWriter.addInt32(arg.length);
        this.packetWriter.add(arg);
      } else {
        const byteLength = this.encoder.encode(arg).length;
        this.packetWriter.addInt32(byteLength);
        this.packetWriter.addString(arg);
      }
    });

    this.packetWriter.addInt16(0);
    const buffer = this.packetWriter.flush(0x42);
    await this.bufWriter.write(buffer);
  }

  async _sendDescribeMessage() {
    this.packetWriter.clear();

    const buffer = this.packetWriter.addCString("P").flush(0x44);
    await this.bufWriter.write(buffer);
  }

  async _sendExecuteMessage() {
    this.packetWriter.clear();

    const buffer = this.packetWriter
      .addCString("") // unnamed portal
      .addInt32(0)
      .flush(0x45);
    await this.bufWriter.write(buffer);
  }

  async _sendFlushMessage() {
    this.packetWriter.clear();

    const buffer = this.packetWriter.flush(0x48);
    await this.bufWriter.write(buffer);
  }

  async _sendSyncMessage() {
    this.packetWriter.clear();

    const buffer = this.packetWriter.flush(0x53);
    await this.bufWriter.write(buffer);
  }

  async _processError(msg: Message) {
    const error = parseError(msg);
    await this._readReadyForQuery();
    throw error;
  }

  private async _readParseComplete() {
    const msg = await this.readMessage();

    switch (msg.type) {
      // parse completed
      case "1":
        // TODO: add to already parsed queries if
        // query has name, so it's not parsed again
        break;
      // error response
      case "E":
        await this._processError(msg);
        break;
      default:
        throw new Error(`Unexpected frame: ${msg.type}`);
    }
  }

  private async _readBindComplete() {
    const msg = await this.readMessage();

    switch (msg.type) {
      // bind completed
      case "2":
        // no-op
        break;
      // error response
      case "E":
        await this._processError(msg);
        break;
      default:
        throw new Error(`Unexpected frame: ${msg.type}`);
    }
  }

  // TODO: I believe error handling here is not correct, shouldn't 'sync' message be
  //  sent after error response is received in prepared statements?
  async _preparedQuery(query: Query): Promise<QueryResult> {
    await this._sendPrepareMessage(query);
    await this._sendBindMessage(query);
    await this._sendDescribeMessage();
    await this._sendExecuteMessage();
    await this._sendSyncMessage();
    // send all messages to backend
    await this.bufWriter.flush();

    await this._readParseComplete();
    await this._readBindComplete();

    const result = query.result;
    let msg: Message;
    msg = await this.readMessage();

    switch (msg.type) {
      // row description
      case "T":
        const rowDescription = this._processRowDescription(msg);
        result.handleRowDescription(rowDescription);
        break;
      // no data
      case "n":
        break;
      // error
      case "E":
        await this._processError(msg);
        break;
      default:
        throw new Error(`Unexpected frame: ${msg.type}`);
    }

    outerLoop:
    while (true) {
      msg = await this.readMessage();
      switch (msg.type) {
        // data row
        case "D":
          // this is actually packet read
          const rawDataRow = this._readDataRow(msg);
          result.handleDataRow(rawDataRow);
          break;
        // command complete
        case "C":
          const commandTag = this._readCommandTag(msg);
          result.handleCommandComplete(commandTag);
          result.done();
          break outerLoop;
        // error response
        case "E":
          await this._processError(msg);
          break;
        default:
          throw new Error(`Unexpected frame: ${msg.type}`);
      }
    }

    await this._readReadyForQuery();

    return result;
  }

  async query(query: Query): Promise<QueryResult> {
    if (query.args.length === 0) {
      return await this._simpleQuery(query);
    }
    return await this._preparedQuery(query);
  }

  private _processRowDescription(msg: Message): RowDescription {
    const columnCount = msg.reader.readInt16();
    const columns = [];

    for (let i = 0; i < columnCount; i++) {
      // TODO: if one of columns has 'format' == 'binary',
      //  all of them will be in same format?
      const column = new Column(
        msg.reader.readCString(), // name
        msg.reader.readInt32(), // tableOid
        msg.reader.readInt16(), // index
        msg.reader.readInt32(), // dataTypeOid
        msg.reader.readInt16(), // column
        msg.reader.readInt32(), // typeModifier
        msg.reader.readInt16(), // format
      );
      columns.push(column);
    }

    return new RowDescription(columnCount, columns);
  }

  _readDataRow(msg: Message): any[] {
    const fieldCount = msg.reader.readInt16();
    const row = [];

    for (let i = 0; i < fieldCount; i++) {
      const colLength = msg.reader.readInt32();

      if (colLength == -1) {
        row.push(null);
        continue;
      }

      // reading raw bytes here, they will be properly parsed later
      row.push(msg.reader.readBytes(colLength));
    }

    return row;
  }

  _readCommandTag(msg: Message) {
    return msg.reader.readString(msg.byteCount);
  }

  async initSQL(): Promise<void> {
    const config: QueryConfig = { text: "select 1;", args: [] };
    const query = new Query(config);
    await this.query(query);
  }

  async end(): Promise<void> {
    const terminationMessage = new Uint8Array([0x58, 0x00, 0x00, 0x00, 0x04]);
    await this.bufWriter.write(terminationMessage);
    await this.bufWriter.flush();
    this.conn.close();
    delete this.conn;
    delete this.bufReader;
    delete this.bufWriter;
    delete this.packetWriter;
  }
}