fix: [http] Consume unread body and trailers before reading next requ…

…est (denoland/deno#3990)

- Added `ServerRequest.finalize()`:  consuming all unread body stream and trailers.
  - This is cleanup method for reading next request from same keep-alive connection.
  - Needed when handler didn't consume all body and trailers even after responding.
- refactor: `ServerRequest._bodyStream()`, `ServerRequestBody` are removed.
  - Now using `bodyReader()` and `chunkedBodyReader()` instead.
- fix: Trailers should only be read `transfer-encoding` is `chunked` and `trailer` header is set and its value is valid.
- fix: use `Headers.append()` on reading trailers.
- fix: delete `trailer` field from headers after reading trailers.
- reorg: Several functions related to IO are moved into `http/io.ts`

http/io.ts

@@ -0,0 +1,213 @@
+import { BufReader, UnexpectedEOFError, BufWriter } from "../io/bufio.ts";
+import { TextProtoReader } from "../textproto/mod.ts";
+import { assert } from "../testing/asserts.ts";
+import { encoder } from "../strings/mod.ts";
+
+export function emptyReader(): Deno.Reader {
+  return {
+    async read(_: Uint8Array): Promise<number | Deno.EOF> {
+      return Deno.EOF;
+    }
+  };
+}
+
+export function bodyReader(contentLength: number, r: BufReader): Deno.Reader {
+  let totalRead = 0;
+  let finished = false;
+  async function read(buf: Uint8Array): Promise<number | Deno.EOF> {
+    if (finished) return Deno.EOF;
+    let result: number | Deno.EOF;
+    const remaining = contentLength - totalRead;
+    if (remaining >= buf.byteLength) {
+      result = await r.read(buf);
+    } else {
+      const readBuf = buf.subarray(0, remaining);
+      result = await r.read(readBuf);
+    }
+    if (result !== Deno.EOF) {
+      totalRead += result;
+    }
+    finished = totalRead === contentLength;
+    return result;
+  }
+  return { read };
+}
+
+export function chunkedBodyReader(h: Headers, r: BufReader): Deno.Reader {
+  // Based on https://tools.ietf.org/html/rfc2616#section-19.4.6
+  const tp = new TextProtoReader(r);
+  let finished = false;
+  const chunks: Array<{
+    offset: number;
+    data: Uint8Array;
+  }> = [];
+  async function read(buf: Uint8Array): Promise<number | Deno.EOF> {
+    if (finished) return Deno.EOF;
+    const [chunk] = chunks;
+    if (chunk) {
+      const chunkRemaining = chunk.data.byteLength - chunk.offset;
+      const readLength = Math.min(chunkRemaining, buf.byteLength);
+      for (let i = 0; i < readLength; i++) {
+        buf[i] = chunk.data[chunk.offset + i];
+      }
+      chunk.offset += readLength;
+      if (chunk.offset === chunk.data.byteLength) {
+        chunks.shift();
+        // Consume \r\n;
+        if ((await tp.readLine()) === Deno.EOF) {
+          throw new UnexpectedEOFError();
+        }
+      }
+      return readLength;
+    }
+    const line = await tp.readLine();
+    if (line === Deno.EOF) throw new UnexpectedEOFError();
+    // TODO: handle chunk extension
+    const [chunkSizeString] = line.split(";");
+    const chunkSize = parseInt(chunkSizeString, 16);
+    if (Number.isNaN(chunkSize) || chunkSize < 0) {
+      throw new Error("Invalid chunk size");
+    }
+    if (chunkSize > 0) {
+      if (chunkSize > buf.byteLength) {
+        let eof = await r.readFull(buf);
+        if (eof === Deno.EOF) {
+          throw new UnexpectedEOFError();
+        }
+        const restChunk = new Uint8Array(chunkSize - buf.byteLength);
+        eof = await r.readFull(restChunk);
+        if (eof === Deno.EOF) {
+          throw new UnexpectedEOFError();
+        } else {
+          chunks.push({
+            offset: 0,
+            data: restChunk
+          });
+        }
+        return buf.byteLength;
+      } else {
+        const bufToFill = buf.subarray(0, chunkSize);
+        const eof = await r.readFull(bufToFill);
+        if (eof === Deno.EOF) {
+          throw new UnexpectedEOFError();
+        }
+        // Consume \r\n
+        if ((await tp.readLine()) === Deno.EOF) {
+          throw new UnexpectedEOFError();
+        }
+        return chunkSize;
+      }
+    } else {
+      assert(chunkSize === 0);
+      // Consume \r\n
+      if ((await r.readLine()) === Deno.EOF) {
+        throw new UnexpectedEOFError();
+      }
+      await readTrailers(h, r);
+      finished = true;
+      return Deno.EOF;
+    }
+  }
+  return { read };
+}
+
+const kProhibitedTrailerHeaders = [
+  "transfer-encoding",
+  "content-length",
+  "trailer"
+];
+
+/**
+ * Read trailer headers from reader and append values to headers.
+ * "trailer" field will be deleted.
+ * */
+export async function readTrailers(
+  headers: Headers,
+  r: BufReader
+): Promise<void> {
+  const keys = parseTrailer(headers.get("trailer"));
+  if (!keys) return;
+  const tp = new TextProtoReader(r);
+  const result = await tp.readMIMEHeader();
+  assert(result != Deno.EOF, "trailer must be set");
+  for (const [k, v] of result) {
+    if (!keys.has(k)) {
+      throw new Error("Undeclared trailer field");
+    }
+    keys.delete(k);
+    headers.append(k, v);
+  }
+  assert(keys.size === 0, "Missing trailers");
+  headers.delete("trailer");
+}
+
+function parseTrailer(field: string | null): Set<string> | undefined {
+  if (field == null) {
+    return undefined;
+  }
+  const keys = field.split(",").map(v => v.trim());
+  if (keys.length === 0) {
+    throw new Error("Empty trailer");
+  }
+  for (const invalid of kProhibitedTrailerHeaders) {
+    if (keys.includes(invalid)) {
+      throw new Error(`Prohibited field for trailer`);
+    }
+  }
+  return new Set(keys);
+}
+
+export async function writeChunkedBody(
+  w: Deno.Writer,
+  r: Deno.Reader
+): Promise<void> {
+  const writer = BufWriter.create(w);
+  for await (const chunk of Deno.toAsyncIterator(r)) {
+    if (chunk.byteLength <= 0) continue;
+    const start = encoder.encode(`${chunk.byteLength.toString(16)}\r\n`);
+    const end = encoder.encode("\r\n");
+    await writer.write(start);
+    await writer.write(chunk);
+    await writer.write(end);
+  }
+
+  const endChunk = encoder.encode("0\r\n\r\n");
+  await writer.write(endChunk);
+}
+
+/** write trailer headers to writer. it mostly should be called after writeResponse */
+export async function writeTrailers(
+  w: Deno.Writer,
+  headers: Headers,
+  trailers: Headers
+): Promise<void> {
+  const trailer = headers.get("trailer");
+  if (trailer === null) {
+    throw new Error('response headers must have "trailer" header field');
+  }
+  const transferEncoding = headers.get("transfer-encoding");
+  if (transferEncoding === null || !transferEncoding.match(/^chunked/)) {
+    throw new Error(
+      `trailer headers is only allowed for "transfer-encoding: chunked": got "${transferEncoding}"`
+    );
+  }
+  const writer = BufWriter.create(w);
+  const trailerHeaderFields = trailer
+    .split(",")
+    .map(s => s.trim().toLowerCase());
+  for (const f of trailerHeaderFields) {
+    assert(
+      !kProhibitedTrailerHeaders.includes(f),
+      `"${f}" is prohibited for trailer header`
+    );
+  }
+  for (const [key, value] of trailers) {
+    assert(
+      trailerHeaderFields.includes(key),
+      `Not trailer header field: ${key}`
+    );
+    await writer.write(encoder.encode(`${key}: ${value}\r\n`));
+  }
+  await writer.write(encoder.encode("\r\n"));
+  await writer.flush();
+}

http/io_test.ts

@@ -0,0 +1,167 @@
+import {
+  AssertionError,
+  assertThrowsAsync,
+  assertEquals
+} from "../testing/asserts.ts";
+import { bodyReader, writeTrailers, readTrailers } from "./io.ts";
+import { encode, decode } from "../strings/mod.ts";
+import { BufReader } from "../io/bufio.ts";
+import { chunkedBodyReader } from "./io.ts";
+const { test, Buffer } = Deno;
+
+test("bodyReader", async () => {
+  const text = "Hello, Deno";
+  const r = bodyReader(text.length, new BufReader(new Buffer(encode(text))));
+  assertEquals(decode(await Deno.readAll(r)), text);
+});
+function chunkify(n: number, char: string): string {
+  const v = Array.from({ length: n })
+    .map(() => `${char}`)
+    .join("");
+  return `${n.toString(16)}\r\n${v}\r\n`;
+}
+test("chunkedBodyReader", async () => {
+  const body = [
+    chunkify(3, "a"),
+    chunkify(5, "b"),
+    chunkify(11, "c"),
+    chunkify(22, "d"),
+    chunkify(0, "")
+  ].join("");
+  const h = new Headers();
+  const r = chunkedBodyReader(h, new BufReader(new Buffer(encode(body))));
+  let result: number | Deno.EOF;
+  // Use small buffer as some chunks exceed buffer size
+  const buf = new Uint8Array(5);
+  const dest = new Buffer();
+  while ((result = await r.read(buf)) !== Deno.EOF) {
+    const len = Math.min(buf.byteLength, result);
+    await dest.write(buf.subarray(0, len));
+  }
+  const exp = "aaabbbbbcccccccccccdddddddddddddddddddddd";
+  assertEquals(dest.toString(), exp);
+});
+
+test("chunkedBodyReader with trailers", async () => {
+  const body = [
+    chunkify(3, "a"),
+    chunkify(5, "b"),
+    chunkify(11, "c"),
+    chunkify(22, "d"),
+    chunkify(0, ""),
+    "deno: land\r\n",
+    "node: js\r\n",
+    "\r\n"
+  ].join("");
+  const h = new Headers({
+    trailer: "deno,node"
+  });
+  const r = chunkedBodyReader(h, new BufReader(new Buffer(encode(body))));
+  assertEquals(h.has("trailer"), true);
+  assertEquals(h.has("deno"), false);
+  assertEquals(h.has("node"), false);
+  const act = decode(await Deno.readAll(r));
+  const exp = "aaabbbbbcccccccccccdddddddddddddddddddddd";
+  assertEquals(act, exp);
+  assertEquals(h.has("trailer"), false);
+  assertEquals(h.get("deno"), "land");
+  assertEquals(h.get("node"), "js");
+});
+
+test("readTrailers", async () => {
+  const h = new Headers({
+    trailer: "deno,node"
+  });
+  const trailer = ["deno: land", "node: js", "", ""].join("\r\n");
+  await readTrailers(h, new BufReader(new Buffer(encode(trailer))));
+  assertEquals(h.has("trailer"), false);
+  assertEquals(h.get("deno"), "land");
+  assertEquals(h.get("node"), "js");
+});
+
+test("readTrailer should throw if undeclared headers found in trailer", async () => {
+  const patterns = [
+    ["deno,node", "deno: land\r\nnode: js\r\ngo: lang\r\n\r\n"],
+    ["deno", "node: js\r\n\r\n"],
+    ["deno", "node:js\r\ngo: lang\r\n\r\n"]
+  ];
+  for (const [header, trailer] of patterns) {
+    const h = new Headers({
+      trailer: header
+    });
+    await assertThrowsAsync(
+      async () => {
+        await readTrailers(h, new BufReader(new Buffer(encode(trailer))));
+      },
+      Error,
+      "Undeclared trailer field"
+    );
+  }
+});
+
+test("readTrailer should throw if trailer contains prohibited fields", async () => {
+  for (const f of ["content-length", "trailer", "transfer-encoding"]) {
+    const h = new Headers({
+      trailer: f
+    });
+    await assertThrowsAsync(
+      async () => {
+        await readTrailers(h, new BufReader(new Buffer()));
+      },
+      Error,
+      "Prohibited field for trailer"
+    );
+  }
+});
+
+test("writeTrailer", async () => {
+  const w = new Buffer();
+  await writeTrailers(
+    w,
+    new Headers({ "transfer-encoding": "chunked", trailer: "deno,node" }),
+    new Headers({ deno: "land", node: "js" })
+  );
+  assertEquals(w.toString(), "deno: land\r\nnode: js\r\n\r\n");
+});
+
+test("writeTrailer should throw", async () => {
+  const w = new Buffer();
+  await assertThrowsAsync(
+    () => {
+      return writeTrailers(w, new Headers(), new Headers());
+    },
+    Error,
+    'must have "trailer"'
+  );
+  await assertThrowsAsync(
+    () => {
+      return writeTrailers(w, new Headers({ trailer: "deno" }), new Headers());
+    },
+    Error,
+    "only allowed"
+  );
+  for (const f of ["content-length", "trailer", "transfer-encoding"]) {
+    await assertThrowsAsync(
+      () => {
+        return writeTrailers(
+          w,
+          new Headers({ "transfer-encoding": "chunked", trailer: f }),
+          new Headers({ [f]: "1" })
+        );
+      },
+      AssertionError,
+      "prohibited"
+    );
+  }
+  await assertThrowsAsync(
+    () => {
+      return writeTrailers(
+        w,
+        new Headers({ "transfer-encoding": "chunked", trailer: "deno" }),
+        new Headers({ node: "js" })
+      );
+    },
+    AssertionError,
+    "Not trailer"
+  );
+});