1 /*
2 * Copyright 2021, The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #include "host/libs/confui/cbor.h"
18
19 #include "common/libs/confui/confui.h"
20
21 namespace cuttlefish {
22 namespace confui {
23 /**
24 * basically, this creates a map as follows:
25 * {"prompt" : prompt_text_in_UTF8,
26 * "extra" : extra_data_in_bytes}
27 */
Init()28 void Cbor::Init() {
29 cn_cbor_errback err;
30 cb_map_ = std::unique_ptr<cn_cbor, CborDeleter>(cn_cbor_map_create(&err));
31
32 buffer_status_ = CheckUTF8Copy(prompt_text_);
33 if (!IsOk()) {
34 return;
35 }
36
37 auto cb_prompt_as_value = cn_cbor_string_create(prompt_text_.data(), &err);
38 auto cb_extra_data_as_value =
39 cn_cbor_data_create(extra_data_.data(), extra_data_.size(), &err);
40 cn_cbor_mapput_string(cb_map_.get(), "prompt", cb_prompt_as_value, &err);
41 cn_cbor_mapput_string(cb_map_.get(), "extra", cb_extra_data_as_value, &err);
42
43 // cn_cbor_encoder_write wants buffer_ to have a trailing 0 at the end
44 auto n_chars =
45 cn_cbor_encoder_write(buffer_.data(), 0, buffer_.size(), cb_map_.get());
46 ConfUiLog(ERROR) << "Cn-cbor encoder wrote " << n_chars << " while "
47 << "kMax is " << kMax;
48 if (n_chars < 0) {
49 // it's either message being too long, or a potential cn_cbor bug
50 ConfUiLog(ERROR) << "Cn-cbor returns -1 which is likely message too long.";
51 buffer_status_ = Error::OUT_OF_DATA;
52 }
53 if (!IsOk()) {
54 return;
55 }
56 buffer_.resize(n_chars);
57 }
58
GetMessage()59 std::vector<std::uint8_t>&& Cbor::GetMessage() { return std::move(buffer_); }
60
CheckUTF8Copy(const std::string & text)61 Cbor::Error Cbor::CheckUTF8Copy(const std::string& text) {
62 auto begin = text.cbegin();
63 auto end = text.cend();
64
65 if (!IsOk()) {
66 return buffer_status_;
67 }
68
69 uint32_t multi_byte_length = 0;
70 Cbor::Error err_code = buffer_status_; // OK
71
72 while (begin != end) {
73 if (multi_byte_length) {
74 // parsing multi byte character - must start with 10xxxxxx
75 --multi_byte_length;
76 if ((*begin & 0xc0) != 0x80) {
77 return Cbor::Error::MALFORMED_UTF8;
78 }
79 } else if (!((*begin) & 0x80)) {
80 // 7bit character -> nothing to be done
81 } else {
82 // msb is set and we were not parsing a multi byte character
83 // so this must be a header byte
84 char c = *begin << 1;
85 while (c & 0x80) {
86 ++multi_byte_length;
87 c <<= 1;
88 }
89 // headers of the form 10xxxxxx are not allowed
90 if (multi_byte_length < 1) {
91 return Cbor::Error::MALFORMED_UTF8;
92 }
93 // chars longer than 4 bytes are not allowed (multi_byte_length does not
94 // count the header thus > 3
95 if (multi_byte_length > 3) {
96 return Cbor::Error::MALFORMED_UTF8;
97 }
98 }
99 ++begin;
100 }
101 // if the string ends in the middle of a multi byte char it is invalid
102 if (multi_byte_length) {
103 return Cbor::Error::MALFORMED_UTF8;
104 }
105 return err_code;
106 }
107 } // end of namespace confui
108 } // end of namespace cuttlefish
109