1 files changed, 213 insertions, 0 deletions
diff --git a/std/http/io.ts b/std/http/io.ts
new file mode 100644
index 000000000..a51fada54
--- /dev/null
+++ b/std/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();
+}