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Backport #5635

String#unpack("M") の不正データ時の振る舞い

Added by tommy (Masahiro Tomita) over 8 years ago. Updated almost 8 years ago.

Status:
Closed
Priority:
Normal
[ruby-dev:44875]

Description

String#unpack("M") で "=hoge" みたいな不正なデータがあった場合、現在は
そこで処理を中断してしまっていますが、それ以降のデータをすべて捨ててし
まうのはかわいそうなので、ポインタを一つ進めて処理を継続した方がいいん
じゃないかと思うのですがどうでしょうか。

RFC2045 には次のような記述があります。

(2)   An "=" followed by a character that is neither a
      hexadecimal digit (including "abcdef") nor the CR
      character of a CRLF pair is illegal.  This case can be
      the result of US-ASCII text having been included in a
      quoted-printable part of a message without itself
      having been subjected to quoted-printable encoding.  A
      reasonable approach by a robust implementation might be
      to include the "=" character and the following
      character in the decoded data without any
      transformation and, if possible, indicate to the user
      that proper decoding was not possible at this point in
      the data.

Index: pack.c

--- pack.c (リビジョン 33758)
+++ pack.c (作業コピー)
@@ -2008,20 +2008,23 @@

    while (s < send) {
        if (*s == '=') {
  • if (++s == send) break;
  • if (s+1 < send && *s == '\r' && *(s+1) == '\n')
  • s++;
  • if (*s != '\n') {
  • if ((c1 = hex2num(*s)) == -1) break;
  • if (++s == send) break;
  • if ((c2 = hex2num(*s)) == -1) break;
  • *ptr++ = c1 << 4 | c2;
  • if (s+1 < send && *(s+1) == '\n') {
  • s += 2;
  • continue;
  • }
  • if (s+2 < send) {
  • if (*(s+1) == '\r' && *(s+2) == '\n') {
  • s += 3;
  • continue;
  • }
  • if ((c1 = hex2num((s+1))) > -1 && (c2 = hex2num((s+2))) > -1) {
  • *ptr++ = c1 << 4 | c2;
  • s += 3;
  • continue;
  • } } }
  • else {
  • *ptr++ = *s;
  • }
  • s++;
  •       *ptr++ = *s++;
    }
    rb_str_set_len(buf, ptr - RSTRING_PTR(buf));
    ENCODING_CODERANGE_SET(buf, rb_ascii8bit_encindex(), ENC_CODERANGE_VALID);
    

    Index: test/ruby/test_pack.rb

    --- test/ruby/test_pack.rb (リビジョン 33758)
    +++ test/ruby/test_pack.rb (作業コピー)
    @@ -612,6 +612,17 @@
    assert_equal([0x100000000], "\220\200\200\200\000".unpack("w"), [0x100000000])
    end

  • def test_pack_unpack_M

  • assert_equal(["pre123after"], "pre=31=32=33after".unpack("M"))

  • assert_equal(["preafter"], "pre=\nafter".unpack("M"))

  • assert_equal(["preafter"], "pre=\r\nafter".unpack("M"))

  • assert_equal(["pre="], "pre=".unpack("M"))

  • assert_equal(["pre=\r"], "pre=\r".unpack("M"))

  • assert_equal(["pre=hoge"], "pre=hoge".unpack("M"))

  • assert_equal(["pre=1after"], "pre==31after".unpack("M"))

  • assert_equal(["pre==1after"], "pre===31after".unpack("M"))

  • end
    +
    def test_modify_under_safe4
    s = "foo"
    assert_raise(SecurityError) do

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