Inside Bitcoin

1// Copyright (c) 2009-2010 Satoshi Nakamoto
2// Copyright (c) 2009-present The Bitcoin Core developers
3// Distributed under the MIT software license, see the accompanying
4// file COPYING or http://www.opensource.org/licenses/mit-license.php.
5
6#include <util/strencodings.h>
7
8#include <crypto/hex_base.h>
9#include <span.h>
10#include <util/check.h>
11#include <util/overflow.h>
12
13#include <limits>
14#include <optional>
15#include <sstream>
16#include <string>
17#include <vector>
18
19static const std::string CHARS_ALPHA_NUM = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
20
21static const std::string SAFE_CHARS[] =
22{
23    CHARS_ALPHA_NUM + " .,;-_/:?@()", // SAFE_CHARS_DEFAULT
24    CHARS_ALPHA_NUM + " .,;-_?@", // SAFE_CHARS_UA_COMMENT
25    CHARS_ALPHA_NUM + ".-_", // SAFE_CHARS_FILENAME
26    CHARS_ALPHA_NUM + "!*'();:@&=+$,/?#[]-_.~%", // SAFE_CHARS_URI
27};
28
29std::string SanitizeString(std::string_view str, int rule)
30{
31    std::string result;
32    for (char c : str) {
33        if (SAFE_CHARS[rule].find(c) != std::string::npos) {
34            result.push_back(c);
35        }
36    }
37    return result;
38}
39
40bool IsHex(std::string_view str)
41{
42    for (char c : str) {
43        if (HexDigit(c) < 0) return false;
44    }
45    return (str.size() > 0) && (str.size()%2 == 0);
46}
47
48template <typename Byte>
49std::optional<std::vector<Byte>> TryParseHex(std::string_view str)
50{
51    std::vector<Byte> vch;
52    vch.reserve(str.size() / 2); // two hex characters form a single byte
53
54    auto it = str.begin();
55    while (it != str.end()) {
56        if (IsSpace(*it)) {
57            ++it;
58            continue;
59        }
60        auto c1 = HexDigit(*(it++));
61        if (it == str.end()) return std::nullopt;
62        auto c2 = HexDigit(*(it++));
63        if (c1 < 0 || c2 < 0) return std::nullopt;
64        vch.push_back(Byte(c1 << 4) | Byte(c2));
65    }
66    return vch;
67}
68template std::optional<std::vector<std::byte>> TryParseHex(std::string_view);
69template std::optional<std::vector<uint8_t>> TryParseHex(std::string_view);
70
71bool SplitHostPort(std::string_view in, uint16_t& portOut, std::string& hostOut)
72{
73    bool valid = false;
74    size_t colon = in.find_last_of(':');
75    // if a : is found, and it either follows a [...], or no other : is in the string, treat it as port separator
76    bool fHaveColon = colon != in.npos;
77    bool fBracketed = fHaveColon && (in[0] == '[' && in[colon - 1] == ']'); // if there is a colon, and in[0]=='[', colon is not 0, so in[colon-1] is safe
78    bool fMultiColon{fHaveColon && colon != 0 && (in.find_last_of(':', colon - 1) != in.npos)};
79    if (fHaveColon && (colon == 0 || fBracketed || !fMultiColon)) {
80        if (const auto n{ToIntegral<uint16_t>(in.substr(colon + 1))}) {
81            in = in.substr(0, colon);
82            portOut = *n;
83            valid = (portOut != 0);
84        }
85    } else {
86        valid = true;
87    }
88    if (in.size() > 0 && in[0] == '[' && in[in.size() - 1] == ']') {
89        hostOut = in.substr(1, in.size() - 2);
90    } else {
91        hostOut = in;
92    }
93
94    return valid;
95}
96
97std::string EncodeBase64(std::span<const unsigned char> input)
98{
99    static const char *pbase64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
100
101    std::string str;
102    str.reserve(CeilDiv(input.size(), 3u) * 4);
103    ConvertBits<8, 6, true>([&](int v) { str += pbase64[v]; }, input.begin(), input.end());
104    while (str.size() % 4) str += '=';
105    return str;
106}
107
108std::optional<std::vector<unsigned char>> DecodeBase64(std::string_view str)
109{
110    static const int8_t decode64_table[256]{
111        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
112        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
113        -1, -1, -1, 62, -1, -1, -1, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1,
114        -1, -1, -1, -1, -1,  0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14,
115        15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1, -1, 26, 27, 28,
116        29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48,
117        49, 50, 51, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
118        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
119        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
120        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
121        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
122        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
123        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1
124    };
125
126    if (str.size() % 4 != 0) return {};
127    /* One or two = characters at the end are permitted. */
128    if (str.size() >= 1 && str.back() == '=') str.remove_suffix(1);
129    if (str.size() >= 1 && str.back() == '=') str.remove_suffix(1);
130
131    std::vector<unsigned char> ret;
132    ret.reserve((str.size() * 3) / 4);
133    bool valid = ConvertBits<6, 8, false>(
134        [&](unsigned char c) { ret.push_back(c); },
135        str.begin(), str.end(),
136        [](char c) { return decode64_table[uint8_t(c)]; }
137    );
138    if (!valid) return {};
139
140    return ret;
141}
142
143std::string EncodeBase32(std::span<const unsigned char> input, bool pad)
144{
145    static const char *pbase32 = "abcdefghijklmnopqrstuvwxyz234567";
146
147    std::string str;
148    str.reserve(CeilDiv(input.size(), 5u) * 8);
149    ConvertBits<8, 5, true>([&](int v) { str += pbase32[v]; }, input.begin(), input.end());
150    if (pad) {
151        while (str.size() % 8) {
152            str += '=';
153        }
154    }
155    return str;
156}
157
158std::string EncodeBase32(std::string_view str, bool pad)
159{
160    return EncodeBase32(MakeUCharSpan(str), pad);
161}
162
163std::optional<std::vector<unsigned char>> DecodeBase32(std::string_view str)
164{
165    static const int8_t decode32_table[256]{
166        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
167        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
168        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 26, 27, 28, 29, 30, 31, -1, -1, -1, -1,
169        -1, -1, -1, -1, -1,  0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14,
170        15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1, -1,  0,  1,  2,
171         3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22,
172        23, 24, 25, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
173        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
174        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
175        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
176        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
177        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
178        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1
179    };
180
181    if (str.size() % 8 != 0) return {};
182    /* 1, 3, 4, or 6 padding '=' suffix characters are permitted. */
183    if (str.size() >= 1 && str.back() == '=') str.remove_suffix(1);
184    if (str.size() >= 2 && str.substr(str.size() - 2) == "==") str.remove_suffix(2);
185    if (str.size() >= 1 && str.back() == '=') str.remove_suffix(1);
186    if (str.size() >= 2 && str.substr(str.size() - 2) == "==") str.remove_suffix(2);
187
188    std::vector<unsigned char> ret;
189    ret.reserve((str.size() * 5) / 8);
190    bool valid = ConvertBits<5, 8, false>(
191        [&](unsigned char c) { ret.push_back(c); },
192        str.begin(), str.end(),
193        [](char c) { return decode32_table[uint8_t(c)]; }
194    );
195
196    if (!valid) return {};
197
198    return ret;
199}
200
201std::string FormatParagraph(std::string_view in, size_t width, size_t indent)
202{
203    assert(width >= indent);
204    std::stringstream out;
205    size_t ptr = 0;
206    size_t indented = 0;
207    while (ptr < in.size())
208    {
209        size_t lineend = in.find_first_of('\n', ptr);
210        if (lineend == std::string::npos) {
211            lineend = in.size();
212        }
213        const size_t linelen = lineend - ptr;
214        const size_t rem_width = width - indented;
215        if (linelen <= rem_width) {
216            out << in.substr(ptr, linelen + 1);
217            ptr = lineend + 1;
218            indented = 0;
219        } else {
220            size_t finalspace = in.find_last_of(" \n", ptr + rem_width);
221            if (finalspace == std::string::npos || finalspace < ptr) {
222                // No place to break; just include the entire word and move on
223                finalspace = in.find_first_of("\n ", ptr);
224                if (finalspace == std::string::npos) {
225                    // End of the string, just add it and break
226                    out << in.substr(ptr);
227                    break;
228                }
229            }
230            out << in.substr(ptr, finalspace - ptr) << "\n";
231            if (in[finalspace] == '\n') {
232                indented = 0;
233            } else if (indent) {
234                out << std::string(indent, ' ');
235                indented = indent;
236            }
237            ptr = finalspace + 1;
238        }
239    }
240    return out.str();
241}
242
243/** Upper bound for mantissa.
244 * 10^18-1 is the largest arbitrary decimal that will fit in a signed 64-bit integer.
245 * Larger integers cannot consist of arbitrary combinations of 0-9:
246 *
247 *   999999999999999999  1^18-1
248 *  9223372036854775807  (1<<63)-1  (max int64_t)
249 *  9999999999999999999  1^19-1     (would overflow)
250 */