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/*
* Copyright (C) 2020 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#pragma once
#include <iomanip>
#include <sstream>
#include <string>
#include <vector>
namespace android::mediametrics::stringutils {
/**
* fieldPrint is a helper method that logs to a stringstream a sequence of
* field names (in a fixed size array) together with a variable number of arg parameters.
*
* stringstream << field[0] << ":" << arg0 << " ";
* stringstream << field[1] << ":" << arg1 << " ";
* ...
* stringstream << field[N-1] << ":" << arg{N-1} << " ";
*
* The number of fields must exactly match the (variable) arguments.
*
* Example:
*
* const char * const fields[] = { "integer" };
* std::stringstream ss;
* fieldPrint(ss, fields, int(10));
*/
template <size_t N, typename... Targs>
void fieldPrint(std::stringstream& ss, const char * const (& fields)[N], Targs... args) {
static_assert(N == sizeof...(args)); // guarantee #fields == #args
auto fptr = fields; // get a pointer to the base of fields array
((ss << *fptr++ << ":" << args << " "), ...); // (fold expression), send to stringstream.
}
/**
* Return string tokens from iterator, separated by spaces and reserved chars.
*/
std::string tokenizer(std::string::const_iterator& it,
const std::string::const_iterator& end, const char *reserved);
/**
* Splits flags string based on delimeters (or, whitespace which is removed).
*/
std::vector<std::string> split(const std::string& flags, const char *delim);
/**
* Parse the devices string and return a vector of device address pairs.
*
* A failure to parse returns early with the contents that were able to be parsed.
*/
std::vector<std::pair<std::string, std::string>> getDeviceAddressPairs(const std::string &devices);
/**
* Replaces targetChars with replaceChar in string, returns number of chars replaced.
*/
size_t replace(std::string &str, const char *targetChars, const char replaceChar);
// RFC 1421, 2045, 2152, 4648(4), 4880
inline constexpr char Base64Table[] =
// 0000000000111111111122222222223333333333444444444455555555556666
// 0123456789012345678901234567890123456789012345678901234567890123
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
// RFC 4648(5) URL-safe Base64 encoding
inline constexpr char Base64UrlTable[] =
// 0000000000111111111122222222223333333333444444444455555555556666
// 0123456789012345678901234567890123456789012345678901234567890123
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_";
// An constexpr struct that transposes/inverts a string conversion table.
struct Transpose {
// constexpr bug, returning char still means -1 == 0xff, so we use unsigned char.
using base_char_t = unsigned char;
static inline constexpr base_char_t INVALID_CHAR = 0xff;
template <size_t N>
explicit constexpr Transpose(const char(&string)[N]) {
for (auto& e : mMap) {
e = INVALID_CHAR;
}
for (size_t i = 0; string[i] != 0; ++i) {
mMap[static_cast<size_t>(string[i]) & 0xff] = i;
}
}
constexpr base_char_t operator[] (size_t n) const {
return n < sizeof(mMap) ? mMap[n] : INVALID_CHAR;
}
constexpr const auto& get() const {
return mMap;
}
private:
base_char_t mMap[256]; // construct an inverse character mapping.
};
// This table is used to convert an input char to a 6 bit (0 - 63) value.
// If the input char is not in the Base64Url charset, Transpose::INVALID_CHAR is returned.
inline constexpr Transpose InverseBase64UrlTable(Base64UrlTable);
// Returns true if s consists of only valid Base64Url characters (no padding chars allowed).
inline constexpr bool isBase64Url(const char *s) {
for (; *s != 0; ++s) {
if (InverseBase64UrlTable[(unsigned char)*s] == Transpose::INVALID_CHAR) return false;
}
return true;
}
// Returns true if s is a valid log session id: exactly 16 Base64Url characters.
//
// logSessionIds are a web-safe Base64Url RFC 4648(5) encoded string of 16 characters
// (representing 96 unique bits 16 * 6).
//
// The string version is considered the reference representation. However, for ease of
// manipulation and comparison, it may be converted to an int128.
//
// For int128 conversion, some common interpretations exist - for example
// (1) the 16 Base64 chars can be converted 6 bits per char to a 96 bit value
// (with the most significant 32 bits as zero) as there are only 12 unique bytes worth of data
// or (2) the 16 Base64 chars can be used to directly fill the 128 bits of int128 assuming
// the 16 chars are 16 bytes, filling the layout of the int128 variable.
// Endianness of the data may follow whatever is convenient in the interpretation as long
// as it is applied to each such conversion of string to int128 identically.
//
inline constexpr bool isLogSessionId(const char *s) {
return std::char_traits<std::decay_t<decltype(*s)>>::length(s) == 16 && isBase64Url(s);
}
// Returns either the original string or an empty string if isLogSessionId check fails.
inline std::string sanitizeLogSessionId(const std::string& string) {
if (isLogSessionId(string.c_str())) return string;
return {}; // if not a logSessionId, return an empty string.
}
inline std::string bytesToString(const std::vector<uint8_t>& bytes, size_t maxSize = SIZE_MAX) {
if (bytes.size() == 0) {
return "{}";
}
std::stringstream ss;
ss << "{";
ss << std::hex << std::setfill('0');
maxSize = std::min(maxSize, bytes.size());
for (size_t i = 0; i < maxSize; ++i) {
ss << " " << std::setw(2) << (int)bytes[i];
}
if (maxSize != bytes.size()) {
ss << " ... }";
} else {
ss << " }";
}
return ss.str();
}
} // namespace android::mediametrics::stringutils