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ladybird/Kernel/Net/NetworkTask.cpp
Liav A 3fd4997fc2 Kernel: Don't allocate memory for names of processes and threads 
Instead, use the FixedCharBuffer class to ensure we always use a static
buffer storage for these names. This ensures that if a Process or a
Thread were created, there's a guarantee that setting a new name will
never fail, as only copying of strings should be done to that static
storage.

The limits which are set are 32 characters for processes' names and 64
characters for thread names - this is because threads' names could be
more verbose than processes' names.
2023-08-09 21:06:54 -06:00

671 lines
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/*
* Copyright (c) 2018-2021, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <Kernel/Debug.h>
#include <Kernel/Locking/Mutex.h>
#include <Kernel/Locking/MutexProtected.h>
#include <Kernel/Net/ARP.h>
#include <Kernel/Net/EtherType.h>
#include <Kernel/Net/EthernetFrameHeader.h>
#include <Kernel/Net/ICMP.h>
#include <Kernel/Net/IPv4.h>
#include <Kernel/Net/IPv4Socket.h>
#include <Kernel/Net/LoopbackAdapter.h>
#include <Kernel/Net/NetworkTask.h>
#include <Kernel/Net/NetworkingManagement.h>
#include <Kernel/Net/Routing.h>
#include <Kernel/Net/TCP.h>
#include <Kernel/Net/TCPSocket.h>
#include <Kernel/Net/UDP.h>
#include <Kernel/Net/UDPSocket.h>
#include <Kernel/Tasks/Process.h>
namespace Kernel {
static void handle_arp(EthernetFrameHeader const&, size_t frame_size);
static void handle_ipv4(EthernetFrameHeader const&, size_t frame_size, UnixDateTime const& packet_timestamp);
static void handle_icmp(EthernetFrameHeader const&, IPv4Packet const&, UnixDateTime const& packet_timestamp);
static void handle_udp(IPv4Packet const&, UnixDateTime const& packet_timestamp);
static void handle_tcp(IPv4Packet const&, UnixDateTime const& packet_timestamp);
static void send_delayed_tcp_ack(TCPSocket& socket);
static void send_tcp_rst(IPv4Packet const& ipv4_packet, TCPPacket const& tcp_packet, RefPtr<NetworkAdapter> adapter);
static void flush_delayed_tcp_acks();
static void retransmit_tcp_packets();
static Thread* network_task = nullptr;
static HashTable<NonnullRefPtr<TCPSocket>>* delayed_ack_sockets;
[[noreturn]] static void NetworkTask_main(void*);
void NetworkTask::spawn()
{
auto [_, first_thread] = MUST(Process::create_kernel_process("Network Task"sv, NetworkTask_main, nullptr));
network_task = first_thread;
}
bool NetworkTask::is_current()
{
return Thread::current() == network_task;
}
void NetworkTask_main(void*)
{
delayed_ack_sockets = new HashTable<NonnullRefPtr<TCPSocket>>;
WaitQueue packet_wait_queue;
int pending_packets = 0;
NetworkingManagement::the().for_each([&](auto& adapter) {
dmesgln("NetworkTask: {} network adapter found: hw={}", adapter.class_name(), adapter.mac_address().to_string());
if (adapter.class_name() == "LoopbackAdapter"sv) {
adapter.set_ipv4_address({ 127, 0, 0, 1 });
adapter.set_ipv4_netmask({ 255, 0, 0, 0 });
}
adapter.on_receive = [&]() {
pending_packets++;
packet_wait_queue.wake_all();
};
});
auto dequeue_packet = [&pending_packets](u8* buffer, size_t buffer_size, UnixDateTime& packet_timestamp) -> size_t {
if (pending_packets == 0)
return 0;
size_t packet_size = 0;
NetworkingManagement::the().for_each([&](auto& adapter) {
if (packet_size || !adapter.has_queued_packets())
return;
packet_size = adapter.dequeue_packet(buffer, buffer_size, packet_timestamp);
pending_packets--;
dbgln_if(NETWORK_TASK_DEBUG, "NetworkTask: Dequeued packet from {} ({} bytes)", adapter.name(), packet_size);
});
return packet_size;
};
size_t buffer_size = 64 * KiB;
auto region_or_error = MM.allocate_kernel_region(buffer_size, "Kernel Packet Buffer"sv, Memory::Region::Access::ReadWrite);
if (region_or_error.is_error())
TODO();
auto buffer_region = region_or_error.release_value();
auto buffer = (u8*)buffer_region->vaddr().get();
UnixDateTime packet_timestamp;
while (!Process::current().is_dying()) {
flush_delayed_tcp_acks();
retransmit_tcp_packets();
size_t packet_size = dequeue_packet(buffer, buffer_size, packet_timestamp);
if (!packet_size) {
auto timeout_time = Duration::from_milliseconds(500);
auto timeout = Thread::BlockTimeout { false, &timeout_time };
[[maybe_unused]] auto result = packet_wait_queue.wait_on(timeout, "NetworkTask"sv);
continue;
}
if (packet_size < sizeof(EthernetFrameHeader)) {
dbgln("NetworkTask: Packet is too small to be an Ethernet packet! ({})", packet_size);
continue;
}
auto& eth = *(EthernetFrameHeader const*)buffer;
dbgln_if(ETHERNET_DEBUG, "NetworkTask: From {} to {}, ether_type={:#04x}, packet_size={}", eth.source().to_string(), eth.destination().to_string(), eth.ether_type(), packet_size);
switch (eth.ether_type()) {
case EtherType::ARP:
handle_arp(eth, packet_size);
break;
case EtherType::IPv4:
handle_ipv4(eth, packet_size, packet_timestamp);
break;
case EtherType::IPv6:
// ignore
break;
default:
dbgln_if(ETHERNET_DEBUG, "NetworkTask: Unknown ethernet type {:#04x}", eth.ether_type());
}
}
Process::current().sys$exit(0);
VERIFY_NOT_REACHED();
}
void handle_arp(EthernetFrameHeader const& eth, size_t frame_size)
{
constexpr size_t minimum_arp_frame_size = sizeof(EthernetFrameHeader) + sizeof(ARPPacket);
if (frame_size < minimum_arp_frame_size) {
dbgln("handle_arp: Frame too small ({}, need {})", frame_size, minimum_arp_frame_size);
return;
}
auto& packet = *static_cast<ARPPacket const*>(eth.payload());
if (packet.hardware_type() != 1 || packet.hardware_address_length() != sizeof(MACAddress)) {
dbgln("handle_arp: Hardware type not ethernet ({:#04x}, len={})", packet.hardware_type(), packet.hardware_address_length());
return;
}
if (packet.protocol_type() != EtherType::IPv4 || packet.protocol_address_length() != sizeof(IPv4Address)) {
dbgln("handle_arp: Protocol type not IPv4 ({:#04x}, len={})", packet.protocol_type(), packet.protocol_address_length());
return;
}
dbgln_if(ARP_DEBUG, "handle_arp: operation={:#04x}, sender={}/{}, target={}/{}",
packet.operation(),
packet.sender_hardware_address().to_string(),
packet.sender_protocol_address().to_string(),
packet.target_hardware_address().to_string(),
packet.target_protocol_address().to_string());
if (!packet.sender_hardware_address().is_zero() && !packet.sender_protocol_address().is_zero()) {
// Someone has this IPv4 address. I guess we can try to remember that.
// FIXME: Protect against ARP spamming.
update_arp_table(packet.sender_protocol_address(), packet.sender_hardware_address(), UpdateTable::Set);
}
if (packet.operation() == ARPOperation::Request) {
// Who has this IP address?
if (auto adapter = NetworkingManagement::the().from_ipv4_address(packet.target_protocol_address())) {
// We do!
dbgln("handle_arp: Responding to ARP request for my IPv4 address ({})", adapter->ipv4_address());
ARPPacket response;
response.set_operation(ARPOperation::Response);
response.set_target_hardware_address(packet.sender_hardware_address());
response.set_target_protocol_address(packet.sender_protocol_address());
response.set_sender_hardware_address(adapter->mac_address());
response.set_sender_protocol_address(adapter->ipv4_address());
adapter->send(packet.sender_hardware_address(), response);
}
return;
}
}
void handle_ipv4(EthernetFrameHeader const& eth, size_t frame_size, UnixDateTime const& packet_timestamp)
{
constexpr size_t minimum_ipv4_frame_size = sizeof(EthernetFrameHeader) + sizeof(IPv4Packet);
if (frame_size < minimum_ipv4_frame_size) {
dbgln("handle_ipv4: Frame too small ({}, need {})", frame_size, minimum_ipv4_frame_size);
return;
}
auto& packet = *static_cast<IPv4Packet const*>(eth.payload());
if (packet.length() < sizeof(IPv4Packet)) {
dbgln("handle_ipv4: IPv4 packet too short ({}, need {})", packet.length(), sizeof(IPv4Packet));
return;
}
size_t actual_ipv4_packet_length = frame_size - sizeof(EthernetFrameHeader);
if (packet.length() > actual_ipv4_packet_length) {
dbgln("handle_ipv4: IPv4 packet claims to be longer than it is ({}, actually {})", packet.length(), actual_ipv4_packet_length);
return;
}
dbgln_if(IPV4_DEBUG, "handle_ipv4: source={}, destination={}", packet.source(), packet.destination());
NetworkingManagement::the().for_each([&](auto& adapter) {
if (adapter.ipv4_address().is_zero() || !adapter.link_up())
return;
auto my_net = adapter.ipv4_address().to_u32() & adapter.ipv4_netmask().to_u32();
auto their_net = packet.source().to_u32() & adapter.ipv4_netmask().to_u32();
if (my_net == their_net)
update_arp_table(packet.source(), eth.source(), UpdateTable::Set);
});
switch ((IPv4Protocol)packet.protocol()) {
case IPv4Protocol::ICMP:
return handle_icmp(eth, packet, packet_timestamp);
case IPv4Protocol::UDP:
return handle_udp(packet, packet_timestamp);
case IPv4Protocol::TCP:
return handle_tcp(packet, packet_timestamp);
default:
dbgln_if(IPV4_DEBUG, "handle_ipv4: Unhandled protocol {:#02x}", packet.protocol());
break;
}
}
void handle_icmp(EthernetFrameHeader const& eth, IPv4Packet const& ipv4_packet, UnixDateTime const& packet_timestamp)
{
auto& icmp_header = *static_cast<ICMPHeader const*>(ipv4_packet.payload());
dbgln_if(ICMP_DEBUG, "handle_icmp: source={}, destination={}, type={:#02x}, code={:#02x}", ipv4_packet.source().to_string(), ipv4_packet.destination().to_string(), icmp_header.type(), icmp_header.code());
{
Vector<NonnullRefPtr<IPv4Socket>> icmp_sockets;
IPv4Socket::all_sockets().with_exclusive([&](auto& sockets) {
for (auto& socket : sockets) {
if (socket.protocol() == (unsigned)IPv4Protocol::ICMP)
icmp_sockets.append(socket);
}
});
for (auto& socket : icmp_sockets)
socket->did_receive(ipv4_packet.source(), 0, { &ipv4_packet, sizeof(IPv4Packet) + ipv4_packet.payload_size() }, packet_timestamp);
}
auto adapter = NetworkingManagement::the().from_ipv4_address(ipv4_packet.destination());
if (!adapter)
return;
if (icmp_header.type() == ICMPType::EchoRequest) {
auto& request = reinterpret_cast<ICMPEchoPacket const&>(icmp_header);
dbgln("handle_icmp: EchoRequest from {}: id={}, seq={}", ipv4_packet.source(), (u16)request.identifier, (u16)request.sequence_number);
size_t icmp_packet_size = ipv4_packet.payload_size();
if (icmp_packet_size < sizeof(ICMPEchoPacket)) {
dbgln("handle_icmp: EchoRequest packet is too small, ignoring.");
return;
}
auto ipv4_payload_offset = adapter->ipv4_payload_offset();
auto packet = adapter->acquire_packet_buffer(ipv4_payload_offset + icmp_packet_size);
if (!packet) {
dbgln("Could not allocate packet buffer while sending ICMP packet");
return;
}
adapter->fill_in_ipv4_header(*packet, adapter->ipv4_address(), eth.source(), ipv4_packet.source(), IPv4Protocol::ICMP, icmp_packet_size, 0, 64);
memset(packet->buffer->data() + ipv4_payload_offset, 0, sizeof(ICMPEchoPacket));
auto& response = *(ICMPEchoPacket*)(packet->buffer->data() + ipv4_payload_offset);
response.header.set_type(ICMPType::EchoReply);
response.header.set_code(0);
response.identifier = request.identifier;
response.sequence_number = request.sequence_number;
if (size_t icmp_payload_size = icmp_packet_size - sizeof(ICMPEchoPacket))
memcpy(response.payload(), request.payload(), icmp_payload_size);
response.header.set_checksum(internet_checksum(&response, icmp_packet_size));
// FIXME: What is the right TTL value here? Is 64 ok? Should we use the same TTL as the echo request?
adapter->send_packet(packet->bytes());
adapter->release_packet_buffer(*packet);
}
}
void handle_udp(IPv4Packet const& ipv4_packet, UnixDateTime const& packet_timestamp)
{
if (ipv4_packet.payload_size() < sizeof(UDPPacket)) {
dbgln("handle_udp: Packet too small ({}, need {})", ipv4_packet.payload_size(), sizeof(UDPPacket));
return;
}
auto& udp_packet = *static_cast<UDPPacket const*>(ipv4_packet.payload());
dbgln_if(UDP_DEBUG, "handle_udp: source={}:{}, destination={}:{}, length={}",
ipv4_packet.source(), udp_packet.source_port(),
ipv4_packet.destination(), udp_packet.destination_port(),
udp_packet.length());
auto socket = UDPSocket::from_port(udp_packet.destination_port());
if (!socket) {
dbgln_if(UDP_DEBUG, "handle_udp: No local UDP socket for {}:{}", ipv4_packet.destination(), udp_packet.destination_port());
return;
}
VERIFY(socket->type() == SOCK_DGRAM);
VERIFY(socket->local_port() == udp_packet.destination_port());
auto& destination = ipv4_packet.destination();
if (destination == IPv4Address(255, 255, 255, 255) || NetworkingManagement::the().from_ipv4_address(destination) || socket->multicast_memberships().contains_slow(destination))
socket->did_receive(ipv4_packet.source(), udp_packet.source_port(), { &ipv4_packet, sizeof(IPv4Packet) + ipv4_packet.payload_size() }, packet_timestamp);
}
void send_delayed_tcp_ack(TCPSocket& socket)
{
VERIFY(socket.mutex().is_locked());
if (!socket.should_delay_next_ack()) {
[[maybe_unused]] auto result = socket.send_ack();
return;
}
delayed_ack_sockets->set(move(socket));
}
void flush_delayed_tcp_acks()
{
Vector<NonnullRefPtr<TCPSocket>, 32> remaining_sockets;
for (auto& socket : *delayed_ack_sockets) {
MutexLocker locker(socket->mutex());
if (socket->should_delay_next_ack()) {
MUST(remaining_sockets.try_append(*socket));
continue;
}
[[maybe_unused]] auto result = socket->send_ack();
}
if (remaining_sockets.size() != delayed_ack_sockets->size()) {
delayed_ack_sockets->clear();
if (remaining_sockets.size() > 0)
dbgln("flush_delayed_tcp_acks: {} sockets remaining", remaining_sockets.size());
for (auto&& socket : remaining_sockets)
delayed_ack_sockets->set(move(socket));
}
}
void send_tcp_rst(IPv4Packet const& ipv4_packet, TCPPacket const& tcp_packet, RefPtr<NetworkAdapter> adapter)
{
auto routing_decision = route_to(ipv4_packet.source(), ipv4_packet.destination(), adapter);
if (routing_decision.is_zero())
return;
auto ipv4_payload_offset = routing_decision.adapter->ipv4_payload_offset();
const size_t options_size = 0;
const size_t tcp_header_size = sizeof(TCPPacket) + options_size;
const size_t buffer_size = ipv4_payload_offset + tcp_header_size;
auto packet = routing_decision.adapter->acquire_packet_buffer(buffer_size);
if (!packet)
return;
routing_decision.adapter->fill_in_ipv4_header(*packet, ipv4_packet.destination(),
routing_decision.next_hop, ipv4_packet.source(), IPv4Protocol::TCP,
buffer_size - ipv4_payload_offset, 0, 64);
auto& rst_packet = *(TCPPacket*)(packet->buffer->data() + ipv4_payload_offset);
rst_packet = {};
rst_packet.set_source_port(tcp_packet.destination_port());
rst_packet.set_destination_port(tcp_packet.source_port());
rst_packet.set_window_size(0);
rst_packet.set_sequence_number(0);
rst_packet.set_ack_number(tcp_packet.sequence_number() + 1);
rst_packet.set_data_offset(tcp_header_size / sizeof(u32));
rst_packet.set_flags(TCPFlags::RST | TCPFlags::ACK);
rst_packet.set_checksum(TCPSocket::compute_tcp_checksum(ipv4_packet.source(), ipv4_packet.destination(), rst_packet, 0));
routing_decision.adapter->send_packet(packet->bytes());
routing_decision.adapter->release_packet_buffer(*packet);
}
void handle_tcp(IPv4Packet const& ipv4_packet, UnixDateTime const& packet_timestamp)
{
if (ipv4_packet.payload_size() < sizeof(TCPPacket)) {
dbgln("handle_tcp: IPv4 payload is too small to be a TCP packet ({}, need {})", ipv4_packet.payload_size(), sizeof(TCPPacket));
return;
}
auto& tcp_packet = *static_cast<TCPPacket const*>(ipv4_packet.payload());
size_t minimum_tcp_header_size = 5 * sizeof(u32);
size_t maximum_tcp_header_size = 15 * sizeof(u32);
if (tcp_packet.header_size() < minimum_tcp_header_size || tcp_packet.header_size() > maximum_tcp_header_size) {
dbgln("handle_tcp: TCP packet header has invalid size {}", tcp_packet.header_size());
}
if (ipv4_packet.payload_size() < tcp_packet.header_size()) {
dbgln("handle_tcp: IPv4 payload is smaller than TCP header claims ({}, supposedly {})", ipv4_packet.payload_size(), tcp_packet.header_size());
return;
}
size_t payload_size = ipv4_packet.payload_size() - tcp_packet.header_size();
dbgln_if(TCP_DEBUG, "handle_tcp: source={}:{}, destination={}:{}, seq_no={}, ack_no={}, flags={:#04x} ({}{}{}{}), window_size={}, payload_size={}",
ipv4_packet.source().to_string(),
tcp_packet.source_port(),
ipv4_packet.destination().to_string(),
tcp_packet.destination_port(),
tcp_packet.sequence_number(),
tcp_packet.ack_number(),
tcp_packet.flags(),
tcp_packet.has_syn() ? "SYN " : "",
tcp_packet.has_ack() ? "ACK " : "",
tcp_packet.has_fin() ? "FIN " : "",
tcp_packet.has_rst() ? "RST " : "",
tcp_packet.window_size(),
payload_size);
auto adapter = NetworkingManagement::the().from_ipv4_address(ipv4_packet.destination());
if (!adapter) {
dbgln("handle_tcp: this packet is not for me, it's for {}", ipv4_packet.destination());
return;
}
IPv4SocketTuple tuple(ipv4_packet.destination(), tcp_packet.destination_port(), ipv4_packet.source(), tcp_packet.source_port());
dbgln_if(TCP_DEBUG, "handle_tcp: looking for socket; tuple={}", tuple.to_string());
auto socket = TCPSocket::from_tuple(tuple);
if (!socket) {
if (!tcp_packet.has_rst()) {
dbgln("handle_tcp: No TCP socket for tuple {}. Sending RST.", tuple.to_string());
send_tcp_rst(ipv4_packet, tcp_packet, adapter);
}
return;
}
MutexLocker locker(socket->mutex());
VERIFY(socket->type() == SOCK_STREAM);
VERIFY(socket->local_port() == tcp_packet.destination_port());
dbgln_if(TCP_DEBUG, "handle_tcp: got socket {}; state={}", socket->tuple().to_string(), TCPSocket::to_string(socket->state()));
socket->receive_tcp_packet(tcp_packet, ipv4_packet.payload_size());
switch (socket->state()) {
case TCPSocket::State::Closed:
dbgln("handle_tcp: unexpected flags in Closed state ({:x}) for socket with tuple {}", tcp_packet.flags(), tuple.to_string());
// TODO: we may want to send an RST here, maybe as a configurable option
return;
case TCPSocket::State::TimeWait:
dbgln("handle_tcp: unexpected flags in TimeWait state ({:x}) for socket with tuple {}", tcp_packet.flags(), tuple.to_string());
(void)socket->send_tcp_packet(TCPFlags::RST);
socket->set_state(TCPSocket::State::Closed);
return;
case TCPSocket::State::Listen:
switch (tcp_packet.flags()) {
case TCPFlags::SYN: {
dbgln_if(TCP_DEBUG, "handle_tcp: incoming connection");
auto& local_address = ipv4_packet.destination();
auto& peer_address = ipv4_packet.source();
auto client_or_error = socket->try_create_client(local_address, tcp_packet.destination_port(), peer_address, tcp_packet.source_port());
if (client_or_error.is_error()) {
dmesgln("handle_tcp: couldn't create client socket: {}", client_or_error.error());
return;
}
auto client = client_or_error.release_value();
MutexLocker locker(client->mutex());
dbgln_if(TCP_DEBUG, "handle_tcp: created new client socket with tuple {}", client->tuple().to_string());
client->set_sequence_number(1000);
client->set_ack_number(tcp_packet.sequence_number() + payload_size + 1);
[[maybe_unused]] auto rc2 = client->send_tcp_packet(TCPFlags::SYN | TCPFlags::ACK);
client->set_state(TCPSocket::State::SynReceived);
return;
}
default:
dbgln("handle_tcp: unexpected flags in Listen state ({:x})", tcp_packet.flags());
// socket->send_tcp_packet(TCPFlags::RST);
return;
}
case TCPSocket::State::SynSent:
switch (tcp_packet.flags()) {
case TCPFlags::SYN:
socket->set_ack_number(tcp_packet.sequence_number() + payload_size + 1);
(void)socket->send_tcp_packet(TCPFlags::SYN | TCPFlags::ACK);
socket->set_state(TCPSocket::State::SynReceived);
return;
case TCPFlags::ACK | TCPFlags::SYN:
socket->set_ack_number(tcp_packet.sequence_number() + payload_size + 1);
(void)socket->send_ack(true);
socket->set_state(TCPSocket::State::Established);
socket->set_setup_state(Socket::SetupState::Completed);
socket->set_connected(true);
return;
case TCPFlags::ACK | TCPFlags::FIN:
socket->set_ack_number(tcp_packet.sequence_number() + payload_size + 1);
send_delayed_tcp_ack(*socket);
socket->set_state(TCPSocket::State::Closed);
socket->set_error(TCPSocket::Error::FINDuringConnect);
socket->set_setup_state(Socket::SetupState::Completed);
return;
case TCPFlags::ACK | TCPFlags::RST:
socket->set_state(TCPSocket::State::Closed);
socket->set_error(TCPSocket::Error::RSTDuringConnect);
socket->set_setup_state(Socket::SetupState::Completed);
return;
default:
dbgln("handle_tcp: unexpected flags in SynSent state ({:x})", tcp_packet.flags());
(void)socket->send_tcp_packet(TCPFlags::RST);
socket->set_state(TCPSocket::State::Closed);
socket->set_error(TCPSocket::Error::UnexpectedFlagsDuringConnect);
socket->set_setup_state(Socket::SetupState::Completed);
return;
}
case TCPSocket::State::SynReceived:
switch (tcp_packet.flags()) {
case TCPFlags::ACK:
socket->set_ack_number(tcp_packet.sequence_number() + payload_size);
switch (socket->direction()) {
case TCPSocket::Direction::Incoming:
if (!socket->has_originator()) {
dbgln("handle_tcp: connection doesn't have an originating socket; maybe it went away?");
(void)socket->send_tcp_packet(TCPFlags::RST);
socket->set_state(TCPSocket::State::Closed);
return;
}
socket->set_state(TCPSocket::State::Established);
socket->set_setup_state(Socket::SetupState::Completed);
socket->release_to_originator();
return;
case TCPSocket::Direction::Outgoing:
socket->set_state(TCPSocket::State::Established);
socket->set_setup_state(Socket::SetupState::Completed);
socket->set_connected(true);
return;
default:
dbgln("handle_tcp: got ACK in SynReceived state but direction is invalid ({})", TCPSocket::to_string(socket->direction()));
(void)socket->send_tcp_packet(TCPFlags::RST);
socket->set_state(TCPSocket::State::Closed);
return;
}
VERIFY_NOT_REACHED();
case TCPFlags::SYN:
dbgln("handle_tcp: ignoring SYN for partially established connection");
return;
default:
dbgln("handle_tcp: unexpected flags in SynReceived state ({:x})", tcp_packet.flags());
(void)socket->send_tcp_packet(TCPFlags::RST);
socket->set_state(TCPSocket::State::Closed);
return;
}
case TCPSocket::State::CloseWait:
switch (tcp_packet.flags()) {
default:
dbgln("handle_tcp: unexpected flags in CloseWait state ({:x})", tcp_packet.flags());
(void)socket->send_tcp_packet(TCPFlags::RST);
socket->set_state(TCPSocket::State::Closed);
return;
}
case TCPSocket::State::LastAck:
switch (tcp_packet.flags()) {
case TCPFlags::ACK:
socket->set_ack_number(tcp_packet.sequence_number() + payload_size);
socket->set_state(TCPSocket::State::Closed);
return;
default:
dbgln("handle_tcp: unexpected flags in LastAck state ({:x})", tcp_packet.flags());
(void)socket->send_tcp_packet(TCPFlags::RST);
socket->set_state(TCPSocket::State::Closed);
return;
}
case TCPSocket::State::FinWait1:
switch (tcp_packet.flags()) {
case TCPFlags::ACK:
socket->set_ack_number(tcp_packet.sequence_number() + payload_size);
socket->set_state(TCPSocket::State::FinWait2);
return;
case TCPFlags::FIN:
socket->set_ack_number(tcp_packet.sequence_number() + payload_size + 1);
socket->set_state(TCPSocket::State::Closing);
(void)socket->send_ack(true);
return;
case TCPFlags::FIN | TCPFlags::ACK:
socket->set_ack_number(tcp_packet.sequence_number() + payload_size + 1);
socket->set_state(TCPSocket::State::TimeWait);
(void)socket->send_ack(true);
return;
default:
dbgln("handle_tcp: unexpected flags in FinWait1 state ({:x})", tcp_packet.flags());
(void)socket->send_tcp_packet(TCPFlags::RST);
socket->set_state(TCPSocket::State::Closed);
return;
}
case TCPSocket::State::FinWait2:
switch (tcp_packet.flags()) {
case TCPFlags::FIN:
socket->set_ack_number(tcp_packet.sequence_number() + payload_size + 1);
socket->set_state(TCPSocket::State::TimeWait);
(void)socket->send_ack(true);
return;
case TCPFlags::ACK | TCPFlags::RST:
// FIXME: Verify that this transition is legitimate.
socket->set_state(TCPSocket::State::Closed);
return;
default:
dbgln("handle_tcp: unexpected flags in FinWait2 state ({:x})", tcp_packet.flags());
(void)socket->send_tcp_packet(TCPFlags::RST);
socket->set_state(TCPSocket::State::Closed);
return;
}
case TCPSocket::State::Closing:
switch (tcp_packet.flags()) {
case TCPFlags::ACK:
socket->set_ack_number(tcp_packet.sequence_number() + payload_size);
socket->set_state(TCPSocket::State::TimeWait);
return;
default:
dbgln("handle_tcp: unexpected flags in Closing state ({:x})", tcp_packet.flags());
(void)socket->send_tcp_packet(TCPFlags::RST);
socket->set_state(TCPSocket::State::Closed);
return;
}
case TCPSocket::State::Established:
if (tcp_packet.has_rst()) {
socket->set_state(TCPSocket::State::Closed);
return;
}
if (tcp_packet.sequence_number() != socket->ack_number()) {
dbgln_if(TCP_DEBUG, "Discarding out of order packet: seq {} vs. ack {}", tcp_packet.sequence_number(), socket->ack_number());
if (socket->duplicate_acks() < TCPSocket::maximum_duplicate_acks) {
dbgln_if(TCP_DEBUG, "Sending ACK with same ack number to trigger fast retransmission");
socket->set_duplicate_acks(socket->duplicate_acks() + 1);
[[maybe_unused]] auto result = socket->send_ack(true);
}
return;
}
socket->set_duplicate_acks(0);
if (tcp_packet.has_fin()) {
if (payload_size != 0)
socket->did_receive(ipv4_packet.source(), tcp_packet.source_port(), { &ipv4_packet, sizeof(IPv4Packet) + ipv4_packet.payload_size() }, packet_timestamp);
socket->set_ack_number(tcp_packet.sequence_number() + payload_size + 1);
send_delayed_tcp_ack(*socket);
socket->set_state(TCPSocket::State::CloseWait);
socket->set_connected(false);
return;
}
if (payload_size) {
if (socket->did_receive(ipv4_packet.source(), tcp_packet.source_port(), { &ipv4_packet, sizeof(IPv4Packet) + ipv4_packet.payload_size() }, packet_timestamp)) {
socket->set_ack_number(tcp_packet.sequence_number() + payload_size);
dbgln_if(TCP_DEBUG, "Got packet with ack_no={}, seq_no={}, payload_size={}, acking it with new ack_no={}, seq_no={}",
tcp_packet.ack_number(), tcp_packet.sequence_number(), payload_size, socket->ack_number(), socket->sequence_number());
send_delayed_tcp_ack(*socket);
}
}
}
}
void retransmit_tcp_packets()
{
// We must keep the sockets alive until after we've unlocked the hash table
// in case retransmit_packets() realizes that it wants to close the socket.
Vector<NonnullRefPtr<TCPSocket>, 16> sockets;
TCPSocket::sockets_for_retransmit().for_each_shared([&](auto const& socket) {
// We ignore allocation failures above the first 16 guaranteed socket slots, as
// we will just retransmit their packets the next time around
(void)sockets.try_append(socket);
});
for (auto& socket : sockets) {
MutexLocker socket_locker(socket->mutex());
socket->retransmit_packets();
}
}
}
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