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ladybird/Kernel/Net/NetworkTask.cpp
sin-ack 3f3f45580a Everywhere: Add sv suffix to strings relying on StringView(char const*) 
Each of these strings would previously rely on StringView's char const*
constructor overload, which would call __builtin_strlen on the string.
Since we now have operator ""sv, we can replace these with much simpler
versions. This opens the door to being able to remove
StringView(char const*).

No functional changes.
2022-07-12 23:11:35 +02:00

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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/Process.h>
namespace Kernel {
static void handle_arp(EthernetFrameHeader const&, size_t frame_size);
static void handle_ipv4(EthernetFrameHeader const&, size_t frame_size, Time const& packet_timestamp);
static void handle_icmp(EthernetFrameHeader const&, IPv4Packet const&, Time const& packet_timestamp);
static void handle_udp(IPv4Packet const&, Time const& packet_timestamp);
static void handle_tcp(IPv4Packet const&, Time const& packet_timestamp);
static void send_delayed_tcp_ack(RefPtr<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<RefPtr<TCPSocket>>* delayed_ack_sockets;
[[noreturn]] static void NetworkTask_main(void*);
void NetworkTask::spawn()
{
RefPtr<Thread> thread;
auto name = KString::try_create("Network Task"sv);
if (name.is_error())
TODO();
(void)Process::create_kernel_process(thread, name.release_value(), NetworkTask_main, nullptr);
network_task = thread;
}
bool NetworkTask::is_current()
{
return Thread::current() == network_task;
}
void NetworkTask_main(void*)
{
delayed_ack_sockets = new HashTable<RefPtr<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, Time& 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();
Time packet_timestamp;
for (;;) {
flush_delayed_tcp_acks();
retransmit_tcp_packets();
size_t packet_size = dequeue_packet(buffer, buffer_size, packet_timestamp);
if (!packet_size) {
auto timeout_time = Time::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());
}
}
}
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, Time 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, Time 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());
{
NonnullRefPtrVector<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, Time 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(RefPtr<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<RefPtr<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, Time 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})", tcp_packet.flags());
// 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})", tcp_packet.flags());
(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.
NonnullRefPtrVector<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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