1 files changed, 174 insertions, 0 deletions
diff --git a/std/textproto/mod.ts b/std/textproto/mod.ts
new file mode 100644
index 000000000..22153d17c
--- /dev/null
+++ b/std/textproto/mod.ts
@@ -0,0 +1,174 @@
+// Based on https://github.com/golang/go/blob/891682/src/net/textproto/
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+import { BufReader, UnexpectedEOFError } from "../io/bufio.ts";
+import { charCode } from "../io/util.ts";
+
+const asciiDecoder = new TextDecoder();
+function str(buf: Uint8Array): string {
+  if (buf == null) {
+    return "";
+  } else {
+    return asciiDecoder.decode(buf);
+  }
+}
+
+export class ProtocolError extends Error {
+  constructor(msg: string) {
+    super(msg);
+    this.name = "ProtocolError";
+  }
+}
+
+export function append(a: Uint8Array, b: Uint8Array): Uint8Array {
+  if (a == null) {
+    return b;
+  } else {
+    const output = new Uint8Array(a.length + b.length);
+    output.set(a, 0);
+    output.set(b, a.length);
+    return output;
+  }
+}
+
+export class TextProtoReader {
+  constructor(readonly r: BufReader) {}
+
+  /** readLine() reads a single line from the TextProtoReader,
+   * eliding the final \n or \r\n from the returned string.
+   */
+  async readLine(): Promise<string | Deno.EOF> {
+    const s = await this.readLineSlice();
+    if (s === Deno.EOF) return Deno.EOF;
+    return str(s);
+  }
+
+  /** ReadMIMEHeader reads a MIME-style header from r.
+   * The header is a sequence of possibly continued Key: Value lines
+   * ending in a blank line.
+   * The returned map m maps CanonicalMIMEHeaderKey(key) to a
+   * sequence of values in the same order encountered in the input.
+   *
+   * For example, consider this input:
+   *
+   *	My-Key: Value 1
+   *	Long-Key: Even
+   *	       Longer Value
+   *	My-Key: Value 2
+   *
+   * Given that input, ReadMIMEHeader returns the map:
+   *
+   *	map[string][]string{
+   *		"My-Key": {"Value 1", "Value 2"},
+   *		"Long-Key": {"Even Longer Value"},
+   *	}
+   */
+  async readMIMEHeader(): Promise<Headers | Deno.EOF> {
+    const m = new Headers();
+    let line: Uint8Array;
+
+    // The first line cannot start with a leading space.
+    let buf = await this.r.peek(1);
+    if (buf === Deno.EOF) {
+      return Deno.EOF;
+    } else if (buf[0] == charCode(" ") || buf[0] == charCode("\t")) {
+      line = (await this.readLineSlice()) as Uint8Array;
+    }
+
+    buf = await this.r.peek(1);
+    if (buf === Deno.EOF) {
+      throw new UnexpectedEOFError();
+    } else if (buf[0] == charCode(" ") || buf[0] == charCode("\t")) {
+      throw new ProtocolError(
+        `malformed MIME header initial line: ${str(line!)}`
+      );
+    }
+
+    while (true) {
+      const kv = await this.readLineSlice(); // readContinuedLineSlice
+      if (kv === Deno.EOF) throw new UnexpectedEOFError();
+      if (kv.byteLength === 0) return m;
+
+      // Key ends at first colon; should not have trailing spaces
+      // but they appear in the wild, violating specs, so we remove
+      // them if present.
+      let i = kv.indexOf(charCode(":"));
+      if (i < 0) {
+        throw new ProtocolError(`malformed MIME header line: ${str(kv)}`);
+      }
+      let endKey = i;
+      while (endKey > 0 && kv[endKey - 1] == charCode(" ")) {
+        endKey--;
+      }
+
+      //let key = canonicalMIMEHeaderKey(kv.subarray(0, endKey));
+      const key = str(kv.subarray(0, endKey));
+
+      // As per RFC 7230 field-name is a token,
+      // tokens consist of one or more chars.
+      // We could return a ProtocolError here,
+      // but better to be liberal in what we
+      // accept, so if we get an empty key, skip it.
+      if (key == "") {
+        continue;
+      }
+
+      // Skip initial spaces in value.
+      i++; // skip colon
+      while (
+        i < kv.byteLength &&
+        (kv[i] == charCode(" ") || kv[i] == charCode("\t"))
+      ) {
+        i++;
+      }
+      const value = str(kv.subarray(i));
+
+      // In case of invalid header we swallow the error
+      // example: "Audio Mode" => invalid due to space in the key
+      try {
+        m.append(key, value);
+      } catch {}
+    }
+  }
+
+  async readLineSlice(): Promise<Uint8Array | Deno.EOF> {
+    // this.closeDot();
+    let line: Uint8Array;
+    while (true) {
+      const r = await this.r.readLine();
+      if (r === Deno.EOF) return Deno.EOF;
+      const { line: l, more } = r;
+
+      // Avoid the copy if the first call produced a full line.
+      if (!line! && !more) {
+        // TODO(ry):
+        // This skipSpace() is definitely misplaced, but I don't know where it
+        // comes from nor how to fix it.
+        if (this.skipSpace(l) === 0) {
+          return new Uint8Array(0);
+        }
+        return l;
+      }
+
+      // @ts-ignore
+      line = append(line, l);
+      if (!more) {
+        break;
+      }
+    }
+    return line;
+  }
+
+  skipSpace(l: Uint8Array): number {
+    let n = 0;
+    for (let i = 0; i < l.length; i++) {
+      if (l[i] === charCode(" ") || l[i] === charCode("\t")) {
+        continue;
+      }
+      n++;
+    }
+    return n;
+  }
+}