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/* Starshatter: The Open Source Project
Copyright (c) 2021-2024, Starshatter: The Open Source Project Contributors
Copyright (c) 2011-2012, Starshatter OpenSource Distribution Contributors
Copyright (c) 1997-2006, Destroyer Studios LLC.
AUTHOR: John DiCamillo
OVERVIEW
========
Generic Network Packet (Datagram) Implementation
*/
#include "NetGram.h"
#include <atomic>
#include <cstdint>
#include <cstring>
#include "NetAddr.h"
#include "NetLayer.h"
static std::atomic<std::uint32_t> net_gram_sequence {1};
/**
* NetGram constructor for ACK packets
*/
NetGram::NetGram() :
retries(0),
packet_id(0),
send_time(0)
{
}
/**
* NetGram constructor for receiving packets from remote hosts
*/
NetGram::NetGram(const NetAddr& src, Text msg) :
addr(src),
retries(0),
send_time(0)
{
body = msg;
if (body.length() >= NET_GRAM_HEADER_SIZE) {
std::uint8_t* data = (std::uint8_t*) body.data();
packet_id =
(static_cast<std::uint32_t>(data[0]) << 24) +
(static_cast<std::uint32_t>(data[1]) << 16) +
(static_cast<std::uint32_t>(data[2]) << 8) +
(static_cast<std::uint32_t>(data[3]));
}
}
/**
* NetGram constructor for composing packets to send to remote hosts
*/
NetGram::NetGram(const NetAddr& dst, Text user_data, int r) :
addr(dst),
retries(r)
{
send_time = NetLayer::GetTime();
packet_id = net_gram_sequence++;
if (retries)
packet_id |= NET_GRAM_RELIABLE;
static std::uint8_t buf[NET_GRAM_MAX_SIZE];
buf[0] = static_cast<std::uint8_t>((packet_id >> 24) & 0xff);
buf[1] = static_cast<std::uint8_t>((packet_id >> 16) & 0xff);
buf[2] = static_cast<std::uint8_t>((packet_id >> 8) & 0xff);
buf[3] = static_cast<std::uint8_t>((packet_id) & 0xff);
int len = user_data.length();
if (len >= NET_GRAM_MAX_SIZE - NET_GRAM_HEADER_SIZE)
len = NET_GRAM_MAX_SIZE - NET_GRAM_HEADER_SIZE - 1;
std::memcpy(buf + NET_GRAM_HEADER_SIZE, user_data.data(), len);
body = Text((char*) buf, len+NET_GRAM_HEADER_SIZE);
}
void
NetGram::Retry()
{
if (retries > 0) {
retries--;
send_time = NetLayer::GetTime();
}
}
NetGram
NetGram::Ack()
{
NetGram ack;
ack.packet_id = packet_id | NET_GRAM_ACK;
ack.send_time = NetLayer::GetTime();
static std::uint8_t buf[NET_GRAM_HEADER_SIZE];
buf[0] = static_cast<std::uint8_t>((ack.packet_id >> 24) & 0xff);
buf[1] = static_cast<std::uint8_t>((ack.packet_id >> 16) & 0xff);
buf[2] = static_cast<std::uint8_t>((ack.packet_id >> 8) & 0xff);
buf[3] = static_cast<std::uint8_t>((ack.packet_id) & 0xff);
ack.body = Text((char*) buf, NET_GRAM_HEADER_SIZE);
return ack;
}
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