url_canon_icu.cc revision 010d83a9304c5a91596085d917d248abff47903a 
1// Copyright 2013 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5// ICU integration functions.
6
7#include <stdlib.h>
8#include <string.h>
9
10#include "base/lazy_instance.h"
11#include "base/logging.h"
12#include "third_party/icu/source/common/unicode/ucnv.h"
13#include "third_party/icu/source/common/unicode/ucnv_cb.h"
14#include "third_party/icu/source/common/unicode/uidna.h"
15#include "url/url_canon_icu.h"
16#include "url/url_canon_internal.h"  // for _itoa_s
17
18namespace url {
19
20namespace {
21
22// Called when converting a character that can not be represented, this will
23// append an escaped version of the numerical character reference for that code
24// point. It is of the form "&#1234;" and we will escape the non-digits to
25// "%26%231234%3B". Why? This is what Netscape did back in the olden days.
26void appendURLEscapedChar(const void* context,
27                          UConverterFromUnicodeArgs* from_args,
28                          const UChar* code_units,
29                          int32_t length,
30                          UChar32 code_point,
31                          UConverterCallbackReason reason,
32                          UErrorCode* err) {
33  if (reason == UCNV_UNASSIGNED) {
34    *err = U_ZERO_ERROR;
35
36    const static int prefix_len = 6;
37    const static char prefix[prefix_len + 1] = "%26%23";  // "&#" percent-escaped
38    ucnv_cbFromUWriteBytes(from_args, prefix, prefix_len, 0, err);
39
40    DCHECK(code_point < 0x110000);
41    char number[8];  // Max Unicode code point is 7 digits.
42    _itoa_s(code_point, number, 10);
43    int number_len = static_cast<int>(strlen(number));
44    ucnv_cbFromUWriteBytes(from_args, number, number_len, 0, err);
45
46    const static int postfix_len = 3;
47    const static char postfix[postfix_len + 1] = "%3B";   // ";" percent-escaped
48    ucnv_cbFromUWriteBytes(from_args, postfix, postfix_len, 0, err);
49  }
50}
51
52// A class for scoping the installation of the invalid character callback.
53class AppendHandlerInstaller {
54 public:
55  // The owner of this object must ensure that the converter is alive for the
56  // duration of this object's lifetime.
57  AppendHandlerInstaller(UConverter* converter) : converter_(converter) {
58    UErrorCode err = U_ZERO_ERROR;
59    ucnv_setFromUCallBack(converter_, appendURLEscapedChar, 0,
60                          &old_callback_, &old_context_, &err);
61  }
62
63  ~AppendHandlerInstaller() {
64    UErrorCode err = U_ZERO_ERROR;
65    ucnv_setFromUCallBack(converter_, old_callback_, old_context_, 0, 0, &err);
66  }
67
68 private:
69  UConverter* converter_;
70
71  UConverterFromUCallback old_callback_;
72  const void* old_context_;
73};
74
75// A wrapper to use LazyInstance<>::Leaky with ICU's UIDNA, a C pointer to
76// a UTS46/IDNA 2008 handling object opened with uidna_openUTS46().
77//
78// We use UTS46 with BiDiCheck to migrate from IDNA 2003 (with unassigned
79// code points allowed) to IDNA 2008 with
80// the backward compatibility in mind. What it does:
81//
82// 1. Use the up-to-date Unicode data.
83// 2. Define a case folding/mapping with the up-to-date Unicode data as
84//    in IDNA 2003.
85// 3. Use transitional mechanism for 4 deviation characters (sharp-s,
86//    final sigma, ZWJ and ZWNJ) for now.
87// 4. Continue to allow symbols and punctuations.
88// 5. Apply new BiDi check rules more permissive than the IDNA 2003 BiDI rules.
89// 6. Do not apply STD3 rules
90// 7. Do not allow unassigned code points.
91//
92// It also closely matches what IE 10 does except for the BiDi check (
93// http://goo.gl/3XBhqw ).
94// See http://http://unicode.org/reports/tr46/ and references therein
95// for more details.
96struct UIDNAWrapper {
97  UIDNAWrapper() {
98    UErrorCode err = U_ZERO_ERROR;
99    // TODO(jungshik): Change options as different parties (browsers,
100    // registrars, search engines) converge toward a consensus.
101    value = uidna_openUTS46(UIDNA_CHECK_BIDI, &err);
102    if (U_FAILURE(err))
103      value = NULL;
104  }
105
106  UIDNA* value;
107};
108
109}  // namespace
110
111ICUCharsetConverter::ICUCharsetConverter(UConverter* converter)
112    : converter_(converter) {
113}
114
115ICUCharsetConverter::~ICUCharsetConverter() {
116}
117
118void ICUCharsetConverter::ConvertFromUTF16(const base::char16* input,
119                                           int input_len,
120                                           CanonOutput* output) {
121  // Install our error handler. It will be called for character that can not
122  // be represented in the destination character set.
123  AppendHandlerInstaller handler(converter_);
124
125  int begin_offset = output->length();
126  int dest_capacity = output->capacity() - begin_offset;
127  output->set_length(output->length());
128
129  do {
130    UErrorCode err = U_ZERO_ERROR;
131    char* dest = &output->data()[begin_offset];
132    int required_capacity = ucnv_fromUChars(converter_, dest, dest_capacity,
133                                            input, input_len, &err);
134    if (err != U_BUFFER_OVERFLOW_ERROR) {
135      output->set_length(begin_offset + required_capacity);
136      return;
137    }
138
139    // Output didn't fit, expand
140    dest_capacity = required_capacity;
141    output->Resize(begin_offset + dest_capacity);
142  } while (true);
143}
144
145static base::LazyInstance<UIDNAWrapper>::Leaky
146    g_uidna = LAZY_INSTANCE_INITIALIZER;
147
148// Converts the Unicode input representing a hostname to ASCII using IDN rules.
149// The output must be ASCII, but is represented as wide characters.
150//
151// On success, the output will be filled with the ASCII host name and it will
152// return true. Unlike most other canonicalization functions, this assumes that
153// the output is empty. The beginning of the host will be at offset 0, and
154// the length of the output will be set to the length of the new host name.
155//
156// On error, this will return false. The output in this case is undefined.
157// TODO(jungshik): use UTF-8/ASCII version of nameToASCII.
158// Change the function signature and callers accordingly to avoid unnecessary
159// conversions in our code. In addition, consider using icu::IDNA's UTF-8/ASCII
160// version with StringByteSink. That way, we can avoid C wrappers and additional
161// string conversion.
162bool IDNToASCII(const base::char16* src, int src_len, CanonOutputW* output) {
163  DCHECK(output->length() == 0);  // Output buffer is assumed empty.
164
165  UIDNA* uidna = g_uidna.Get().value;
166  DCHECK(uidna != NULL);
167  while (true) {
168    UErrorCode err = U_ZERO_ERROR;
169    UIDNAInfo info = UIDNA_INFO_INITIALIZER;
170    int output_length = uidna_nameToASCII(uidna, src, src_len, output->data(),
171                                          output->capacity(), &info, &err);
172    if (U_SUCCESS(err) && info.errors == 0) {
173      output->set_length(output_length);
174      return true;
175    }
176
177    // TODO(jungshik): Look at info.errors to handle them case-by-case basis
178    // if necessary.
179    if (err != U_BUFFER_OVERFLOW_ERROR || info.errors != 0)
180      return false;  // Unknown error, give up.
181
182    // Not enough room in our buffer, expand.
183    output->Resize(output_length);
184  }
185}
186
187}  // namespace url
188