index.ts

// Copyright 2019-2023 Tauri Programme within The Commons Conservancy
// SPDX-License-Identifier: Apache-2.0
// SPDX-License-Identifier: MIT

/**
 * Make HTTP requests with the Rust backend.
 *
 * ## Security
 *
 * This API has a scope configuration that forces you to restrict the URLs that can be accessed using glob patterns.
 *
 * For instance, this scope configuration only allows making HTTP requests to all subdomains for `tauri.app` except for `https://private.tauri.app`:
 * ```json
 * {
 *   "permissions": [
 *     {
 *       "identifier": "http:default",
 *       "allow": [{ "url": "https://*.tauri.app" }],
 *       "deny": [{ "url": "https://private.tauri.app" }]
 *     }
 *   ]
 * }
 * ```
 * Trying to execute any API with a URL not configured on the scope results in a promise rejection due to denied access.
 *
 * @module
 */

import { Channel, invoke } from '@tauri-apps/api/core'

/**
 * Configuration of a proxy that a Client should pass requests to.
 *
 * @since 2.0.0
 */
export interface Proxy {
  /**
   * Proxy all traffic to the passed URL.
   */
  all?: string | ProxyConfig
  /**
   * Proxy all HTTP traffic to the passed URL.
   */
  http?: string | ProxyConfig
  /**
   * Proxy all HTTPS traffic to the passed URL.
   */
  https?: string | ProxyConfig
}

export interface ProxyConfig {
  /**
   * The URL of the proxy server.
   */
  url: string
  /**
   * Set the `Proxy-Authorization` header using Basic auth.
   */
  basicAuth?: {
    username: string
    password: string
  }
  /**
   * A configuration for filtering out requests that shouldn't be proxied.
   * Entries are expected to be comma-separated (whitespace between entries is ignored)
   */
  noProxy?: string
}

/**
 * Options to configure the Rust client used to make fetch requests
 *
 * @since 2.0.0
 */
export interface ClientOptions {
  /**
   * Defines the maximum number of redirects the client should follow.
   * If set to 0, no redirects will be followed.
   */
  maxRedirections?: number
  /** Timeout in milliseconds */
  connectTimeout?: number
  /**
   * Configuration of a proxy that a Client should pass requests to.
   */
  proxy?: Proxy
  /**
   * Configuration for dangerous settings on the client such as disabling SSL verification.
   */
  danger?: DangerousSettings
}

/**
 * Configuration for dangerous settings on the client such as disabling SSL verification.
 *
 * @since 2.3.0
 */
export interface DangerousSettings {
  /**
   * Disables SSL verification.
   */
  acceptInvalidCerts?: boolean
  /**
   * Disables hostname verification.
   */
  acceptInvalidHostnames?: boolean
}

const ERROR_REQUEST_CANCELLED = 'Request cancelled'

/**
 * Fetch a resource from the network. It returns a `Promise` that resolves to the
 * `Response` to that `Request`, whether it is successful or not.
 *
 * @example
 * ```typescript
 * const response = await fetch("http://my.json.host/data.json");
 * console.log(response.status);  // e.g. 200
 * console.log(response.statusText); // e.g. "OK"
 * const jsonData = await response.json();
 * ```
 *
 * @since 2.0.0
 */
export async function fetch(
  input: URL | Request | string,
  init?: RequestInit & ClientOptions
): Promise<Response> {
  // abort early here if needed
  const signal = init?.signal
  if (signal?.aborted) {
    throw new Error(ERROR_REQUEST_CANCELLED)
  }

  const maxRedirections = init?.maxRedirections
  const connectTimeout = init?.connectTimeout
  const proxy = init?.proxy
  const danger = init?.danger

  // Remove these fields before creating the request
  if (init) {
    delete init.maxRedirections
    delete init.connectTimeout
    delete init.proxy
    delete init.danger
  }

  const headers = init?.headers
    ? init.headers instanceof Headers
      ? init.headers
      : new Headers(init.headers)
    : new Headers()

  const req = new Request(input, init)
  const buffer = await req.arrayBuffer()
  const data =
    buffer.byteLength !== 0 ? Array.from(new Uint8Array(buffer)) : null

  // append new headers created by the browser `Request` implementation,
  // if not already declared by the caller of this function
  for (const [key, value] of req.headers) {
    if (!headers.get(key)) {
      headers.set(key, value)
    }
  }

  const headersArray =
    headers instanceof Headers
      ? Array.from(headers.entries())
      : Array.isArray(headers)
        ? headers
        : Object.entries(headers)

  // eslint-disable-next-line @typescript-eslint/no-unsafe-assignment
  const mappedHeaders: Array<[string, string]> = headersArray.map(
    ([name, val]) => [
      name,
      // we need to ensure we have all header values as strings
      // eslint-disable-next-line
      typeof val === 'string' ? val : (val as any).toString()
    ]
  )

  // abort early here if needed
  if (signal?.aborted) {
    throw new Error(ERROR_REQUEST_CANCELLED)
  }

  const rid = await invoke<number>('plugin:http|fetch', {
    clientConfig: {
      method: req.method,
      url: req.url,
      headers: mappedHeaders,
      data,
      maxRedirections,
      connectTimeout,
      proxy,
      danger
    }
  })

  const abort = () => invoke('plugin:http|fetch_cancel', { rid })

  // abort early here if needed
  if (signal?.aborted) {
    // we don't care about the result of this proimse
    // eslint-disable-next-line @typescript-eslint/no-floating-promises
    abort()
    throw new Error(ERROR_REQUEST_CANCELLED)
  }

  signal?.addEventListener('abort', () => void abort())

  interface FetchSendResponse {
    status: number
    statusText: string
    headers: [[string, string]]
    url: string
    rid: number
  }

  const {
    status,
    statusText,
    url,
    headers: responseHeaders,
    rid: responseRid
  } = await invoke<FetchSendResponse>('plugin:http|fetch_send', {
    rid
  })

  // no body for 204, 205 and 304
  // see https://searchfox.org/mozilla-central/source/dom/fetch/Response.cpp#258
  const body = [204, 205, 304].includes(status)
    ? null
    : new ReadableStream({
        start: (controller) => {
          const streamChannel = new Channel<ArrayBuffer | number[]>()
          streamChannel.onmessage = (res: ArrayBuffer | number[]) => {
            // close early if aborted
            if (signal?.aborted) {
              controller.error(ERROR_REQUEST_CANCELLED)
              return
            }

            const resUint8 = new Uint8Array(res)
            const lastByte = resUint8[resUint8.byteLength - 1]
            const actualRes = resUint8.slice(0, resUint8.byteLength - 1)

            // close when the signal to close (last byte is 1) is sent from the IPC.
            if (lastByte == 1) {
              controller.close()
              return
            }

            controller.enqueue(actualRes)
          }

          // run a non-blocking body stream fetch
          invoke('plugin:http|fetch_read_body', {
            rid: responseRid,
            streamChannel
          }).catch((e) => {
            controller.error(e)
          })
        }
      })

  const res = new Response(body, {
    status,
    statusText
  })

  // Set `Response` properties that are ignored by the
  // constructor, like url and some headers
  //
  // Since url and headers are read only properties
  // this is the only way to set them.
  Object.defineProperty(res, 'url', { value: url })
  Object.defineProperty(res, 'headers', {
    value: new Headers(responseHeaders)
  })

  return res
}