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/*
* Copyright 2022 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 <chrono>
#include <cstdint>
#include <limits>
#include <ostream>
namespace rootcanal::pcap {
using namespace std::literals;
static void WriteHeader(std::ostream& output, uint32_t linktype) {
// https://tools.ietf.org/id/draft-gharris-opsawg-pcap-00.html#name-file-header
uint32_t magic_number = 0xa1b2c3d4;
uint16_t major_version = 2;
uint16_t minor_version = 4;
uint32_t reserved1 = 0;
uint32_t reserved2 = 0;
uint32_t snaplen = std::numeric_limits<uint32_t>::max();
output.write((char*)&magic_number, 4);
output.write((char*)&major_version, 2);
output.write((char*)&minor_version, 2);
output.write((char*)&reserved1, 4);
output.write((char*)&reserved2, 4);
output.write((char*)&snaplen, 4);
output.write((char*)&linktype, 4);
}
static void WriteRecordHeader(std::ostream& output, uint32_t length) {
auto time = std::chrono::system_clock::now().time_since_epoch();
// https://tools.ietf.org/id/draft-gharris-opsawg-pcap-00.html#name-packet-record
uint32_t seconds = time / 1s;
uint32_t microseconds = (time % 1s) / 1ms;
uint32_t captured_packet_length = length;
uint32_t original_packet_length = length;
output.write((char*)&seconds, 4);
output.write((char*)µseconds, 4);
output.write((char*)&captured_packet_length, 4);
output.write((char*)&original_packet_length, 4);
}
} // namespace rootcanal::pcap
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