util.cc

Go to the documentation of this file.

#include "util.hh"
 
#include <array>
#include <cctype>
#include <chrono>
#include <iomanip>
#include <iostream>
#include <sstream>
#include <sys/socket.h>
 
using namespace std;
 
uint64_t timestamp_ms() {
    using time_point = std::chrono::steady_clock::time_point;
    static const time_point program_start = std::chrono::steady_clock::now();
    const time_point now = std::chrono::steady_clock::now();
    return std::chrono::duration_cast<std::chrono::milliseconds>(now - program_start).count();
}
 
int SystemCall(const char *attempt, const int return_value, const int errno_mask) {
    if (return_value >= 0 || errno == errno_mask) {
        return return_value;
    }
 
    throw unix_error(attempt);
}
 
int SystemCall(const string &attempt, const int return_value, const int errno_mask) {
    return SystemCall(attempt.c_str(), return_value, errno_mask);
}
 
mt19937 get_random_generator() {
    auto rd = random_device();
    array<uint32_t, mt19937::state_size> seed_data{};
    generate(seed_data.begin(), seed_data.end(), [&] { return rd(); });
    seed_seq seed(seed_data.begin(), seed_data.end());
    return mt19937(seed);
}
 
InternetChecksum::InternetChecksum(const uint32_t initial_sum) : _sum(initial_sum) {}
 
void InternetChecksum::add(std::string_view data) {
    for (size_t i = 0; i < data.size(); i++) {
        uint16_t val = uint8_t(data[i]);
        if (not _parity) {
            val <<= 8;
        }
        _sum += val;
        _parity = !_parity;
    }
}
 
uint16_t InternetChecksum::value() const {
    uint32_t ret = _sum;
 
    while (ret > 0xffff) {
        ret = (ret >> 16) + (ret & 0xffff);
    }
 
    return ~ret;
}
 
void hexdump(const uint8_t *data, const size_t len, const size_t indent) {
    const auto flags(cout.flags());
    const string indent_string(indent, ' ');
    int printed = 0;
    stringstream pchars(" ");
    cout << hex << setfill('0');
    for (unsigned i = 0; i < len; ++i) {
        if ((printed & 0xf) == 0) {
            if (printed != 0) {
                cout << "    " << pchars.str() << "\n";
                pchars.str(" ");
            }
            cout << indent_string << setw(8) << printed << ":    ";
        } else if ((printed & 1) == 0) {
            cout << ' ';
        }
        cout << setw(2) << +data[i];
        pchars << (static_cast<bool>(isprint(data[i])) ? static_cast<char>(data[i]) : '.');
        printed += 1;
    }
    const int print_rem = (16 - (printed & 0xf)) % 16;  // extra spacing before final chars
    cout << string(2 * print_rem + print_rem / 2 + 4, ' ') << pchars.str();
    cout << '\n' << endl;
    cout.flags(flags);
}
 
void hexdump(const char *data, const size_t len, const size_t indent) {
    hexdump(reinterpret_cast<const uint8_t *>(data), len, indent);
}