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serenity/Kernel/Net/NetworkTask.cpp
Tom c8d9f1b9c9 Kernel: Make copy_to/from_user safe and remove unnecessary checks 
Since the CPU already does almost all necessary validation steps
for us, we don't really need to attempt to do this. Doing it
ourselves doesn't really work very reliably, because we'd have to
account for other processors modifying virtual memory, and we'd
have to account for e.g. pages not being able to be allocated
due to insufficient resources.

So change the copy_to/from_user (and associated helper functions)
to use the new safe_memcpy, which will return whether it succeeded
or not. The only manual validation step needed (which the CPU
can't perform for us) is making sure the pointers provided by user
mode aren't pointing to kernel mappings.

To make it easier to read/write from/to either kernel or user mode
data add the UserOrKernelBuffer helper class, which will internally
either use copy_from/to_user or directly memcpy, or pass the data
through directly using a temporary buffer on the stack.

Last but not least we need to keep syscall params trivial as we
need to copy them from/to user mode using copy_from/to_user.
2020-09-13 21:19:15 +02:00

574 lines
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/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <Kernel/Lock.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/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>
//#define NETWORK_TASK_DEBUG
//#define ETHERNET_DEBUG
//#define ETHERNET_VERY_DEBUG
//#define ARP_DEBUG
//#define IPV4_DEBUG
//#define ICMP_DEBUG
//#define UDP_DEBUG
//#define TCP_DEBUG
namespace Kernel {
static void handle_arp(const EthernetFrameHeader&, size_t frame_size);
static void handle_ipv4(const EthernetFrameHeader&, size_t frame_size);
static void handle_icmp(const EthernetFrameHeader&, const IPv4Packet&);
static void handle_udp(const IPv4Packet&);
static void handle_tcp(const IPv4Packet&);
[[noreturn]] static void NetworkTask_main();
void NetworkTask::spawn()
{
Thread* thread = nullptr;
Process::create_kernel_process(thread, "NetworkTask", NetworkTask_main);
}
void NetworkTask_main()
{
WaitQueue packet_wait_queue;
u8 octet = 15;
int pending_packets = 0;
NetworkAdapter::for_each([&](auto& adapter) {
if (String(adapter.class_name()) == "LoopbackAdapter") {
adapter.set_ipv4_address({ 127, 0, 0, 1 });
adapter.set_ipv4_netmask({ 255, 0, 0, 0 });
adapter.set_ipv4_gateway({ 0, 0, 0, 0 });
} else {
adapter.set_ipv4_address({ 10, 0, 2, octet++ });
adapter.set_ipv4_netmask({ 255, 255, 255, 0 });
adapter.set_ipv4_gateway({ 10, 0, 2, 2 });
}
klog() << "NetworkTask: " << adapter.class_name() << " network adapter found: hw=" << adapter.mac_address().to_string().characters() << " address=" << adapter.ipv4_address().to_string().characters() << " netmask=" << adapter.ipv4_netmask().to_string().characters() << " gateway=" << adapter.ipv4_gateway().to_string().characters();
adapter.on_receive = [&]() {
pending_packets++;
packet_wait_queue.wake_all();
};
});
auto dequeue_packet = [&pending_packets](u8* buffer, size_t buffer_size) -> size_t {
if (pending_packets == 0)
return 0;
size_t packet_size = 0;
NetworkAdapter::for_each([&](auto& adapter) {
if (packet_size || !adapter.has_queued_packets())
return;
packet_size = adapter.dequeue_packet(buffer, buffer_size);
pending_packets--;
#ifdef NETWORK_TASK_DEBUG
klog() << "NetworkTask: Dequeued packet from " << adapter.name().characters() << " (" << packet_size << " bytes)";
#endif
});
return packet_size;
};
size_t buffer_size = 64 * KiB;
auto buffer_region = MM.allocate_kernel_region(buffer_size, "Kernel Packet Buffer", Region::Access::Read | Region::Access::Write, false, true);
auto buffer = (u8*)buffer_region->vaddr().get();
klog() << "NetworkTask: Enter main loop.";
for (;;) {
size_t packet_size = dequeue_packet(buffer, buffer_size);
if (!packet_size) {
Thread::current()->wait_on(packet_wait_queue, "NetworkTask");
continue;
}
if (packet_size < sizeof(EthernetFrameHeader)) {
klog() << "NetworkTask: Packet is too small to be an Ethernet packet! (" << packet_size << ")";
continue;
}
auto& eth = *(const EthernetFrameHeader*)buffer;
#ifdef ETHERNET_DEBUG
klog() << "NetworkTask: From " << eth.source().to_string().characters() << " to " << eth.destination().to_string().characters() << ", ether_type=" << String::format("%w", eth.ether_type()) << ", packet_length=" << packet_size;
#endif
#ifdef ETHERNET_VERY_DEBUG
for (size_t i = 0; i < packet_size; i++) {
klog() << String::format("%b", buffer[i]);
switch (i % 16) {
case 7:
klog() << " ";
break;
case 15:
klog() << "";
break;
default:
klog() << " ";
break;
}
}
klog() << "";
#endif
switch (eth.ether_type()) {
case EtherType::ARP:
handle_arp(eth, packet_size);
break;
case EtherType::IPv4:
handle_ipv4(eth, packet_size);
break;
case EtherType::IPv6:
// ignore
break;
default:
klog() << "NetworkTask: Unknown ethernet type 0x" << String::format("%x", eth.ether_type());
}
}
}
void handle_arp(const EthernetFrameHeader& eth, size_t frame_size)
{
constexpr size_t minimum_arp_frame_size = sizeof(EthernetFrameHeader) + sizeof(ARPPacket);
if (frame_size < minimum_arp_frame_size) {
klog() << "handle_arp: Frame too small (" << frame_size << ", need " << minimum_arp_frame_size << ")";
return;
}
auto& packet = *static_cast<const ARPPacket*>(eth.payload());
if (packet.hardware_type() != 1 || packet.hardware_address_length() != sizeof(MACAddress)) {
klog() << "handle_arp: Hardware type not ethernet (" << String::format("%w", packet.hardware_type()) << ", len=" << packet.hardware_address_length() << ")";
return;
}
if (packet.protocol_type() != EtherType::IPv4 || packet.protocol_address_length() != sizeof(IPv4Address)) {
klog() << "handle_arp: Protocol type not IPv4 (" << String::format("%w", packet.hardware_type()) << ", len=" << packet.protocol_address_length() << ")";
return;
}
#ifdef ARP_DEBUG
klog() << "handle_arp: operation=" << String::format("%w", packet.operation()) << ", sender=" << packet.sender_hardware_address().to_string().characters() << "/" << packet.sender_protocol_address().to_string().characters() << ", target=" << packet.target_hardware_address().to_string().characters() << "/" << packet.target_protocol_address().to_string().characters();
#endif
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.
// FIXME: Support static ARP table entries.
LOCKER(arp_table().lock());
arp_table().resource().set(packet.sender_protocol_address(), packet.sender_hardware_address());
klog() << "ARP table (" << arp_table().resource().size() << " entries):";
for (auto& it : arp_table().resource()) {
klog() << it.value.to_string().characters() << " :: " << it.key.to_string().characters();
}
}
if (packet.operation() == ARPOperation::Request) {
// Who has this IP address?
if (auto adapter = NetworkAdapter::from_ipv4_address(packet.target_protocol_address())) {
// We do!
klog() << "handle_arp: Responding to ARP request for my IPv4 address (" << adapter->ipv4_address().to_string().characters() << ")";
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(const EthernetFrameHeader& eth, size_t frame_size)
{
constexpr size_t minimum_ipv4_frame_size = sizeof(EthernetFrameHeader) + sizeof(IPv4Packet);
if (frame_size < minimum_ipv4_frame_size) {
klog() << "handle_ipv4: Frame too small (" << frame_size << ", need " << minimum_ipv4_frame_size << ")";
return;
}
auto& packet = *static_cast<const IPv4Packet*>(eth.payload());
if (packet.length() < sizeof(IPv4Packet)) {
klog() << "handle_ipv4: IPv4 packet too short (" << packet.length() << ", need " << sizeof(IPv4Packet) << ")";
return;
}
size_t actual_ipv4_packet_length = frame_size - sizeof(EthernetFrameHeader);
if (packet.length() > actual_ipv4_packet_length) {
klog() << "handle_ipv4: IPv4 packet claims to be longer than it is (" << packet.length() << ", actually " << actual_ipv4_packet_length << ")";
return;
}
#ifdef IPV4_DEBUG
klog() << "handle_ipv4: source=" << packet.source().to_string().characters() << ", target=" << packet.destination().to_string().characters();
#endif
switch ((IPv4Protocol)packet.protocol()) {
case IPv4Protocol::ICMP:
return handle_icmp(eth, packet);
case IPv4Protocol::UDP:
return handle_udp(packet);
case IPv4Protocol::TCP:
return handle_tcp(packet);
default:
klog() << "handle_ipv4: Unhandled protocol " << packet.protocol();
break;
}
}
void handle_icmp(const EthernetFrameHeader& eth, const IPv4Packet& ipv4_packet)
{
auto& icmp_header = *static_cast<const ICMPHeader*>(ipv4_packet.payload());
#ifdef ICMP_DEBUG
klog() << "handle_icmp: source=" << ipv4_packet.source().to_string().characters() << ", destination=" << ipv4_packet.destination().to_string().characters() << ", type=" << String::format("%b", icmp_header.type()) << ", code=" << String::format("%b", icmp_header.code());
#endif
{
LOCKER(IPv4Socket::all_sockets().lock());
for (RefPtr<IPv4Socket> socket : IPv4Socket::all_sockets().resource()) {
LOCKER(socket->lock());
if (socket->protocol() != (unsigned)IPv4Protocol::ICMP)
continue;
socket->did_receive(ipv4_packet.source(), 0, KBuffer::copy(&ipv4_packet, sizeof(IPv4Packet) + ipv4_packet.payload_size()));
}
}
auto adapter = NetworkAdapter::from_ipv4_address(ipv4_packet.destination());
if (!adapter)
return;
if (icmp_header.type() == ICMPType::EchoRequest) {
auto& request = reinterpret_cast<const ICMPEchoPacket&>(icmp_header);
klog() << "handle_icmp: EchoRequest from " << ipv4_packet.source().to_string().characters() << ": id=" << (u16)request.identifier << ", seq=" << (u16)request.sequence_number;
size_t icmp_packet_size = ipv4_packet.payload_size();
auto buffer = ByteBuffer::create_zeroed(icmp_packet_size);
auto& response = *(ICMPEchoPacket*)buffer.data();
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?
auto response_buffer = UserOrKernelBuffer::for_kernel_buffer((u8*)&response);
adapter->send_ipv4(eth.source(), ipv4_packet.source(), IPv4Protocol::ICMP, response_buffer, buffer.size(), 64);
}
}
void handle_udp(const IPv4Packet& ipv4_packet)
{
if (ipv4_packet.payload_size() < sizeof(UDPPacket)) {
klog() << "handle_udp: Packet too small (" << ipv4_packet.payload_size() << ", need " << sizeof(UDPPacket) << ")";
return;
}
auto adapter = NetworkAdapter::from_ipv4_address(ipv4_packet.destination());
if (!adapter && ipv4_packet.destination() != IPv4Address(255, 255, 255, 255)) {
klog() << "handle_udp: this packet is not for me, it's for " << ipv4_packet.destination().to_string().characters();
return;
}
auto& udp_packet = *static_cast<const UDPPacket*>(ipv4_packet.payload());
#ifdef UDP_DEBUG
klog() << "handle_udp: source=" << ipv4_packet.source().to_string().characters() << ":" << udp_packet.source_port() << ", destination=" << ipv4_packet.destination().to_string().characters() << ":" << udp_packet.destination_port() << " length=" << udp_packet.length();
#endif
auto socket = UDPSocket::from_port(udp_packet.destination_port());
if (!socket) {
klog() << "handle_udp: No UDP socket for port " << udp_packet.destination_port();
return;
}
ASSERT(socket->type() == SOCK_DGRAM);
ASSERT(socket->local_port() == udp_packet.destination_port());
socket->did_receive(ipv4_packet.source(), udp_packet.source_port(), KBuffer::copy(&ipv4_packet, sizeof(IPv4Packet) + ipv4_packet.payload_size()));
}
void handle_tcp(const IPv4Packet& ipv4_packet)
{
if (ipv4_packet.payload_size() < sizeof(TCPPacket)) {
klog() << "handle_tcp: IPv4 payload is too small to be a TCP packet (" << ipv4_packet.payload_size() << ", need " << sizeof(TCPPacket) << ")";
return;
}
auto& tcp_packet = *static_cast<const TCPPacket*>(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) {
klog() << "handle_tcp: TCP packet header has invalid size " << tcp_packet.header_size();
}
if (ipv4_packet.payload_size() < tcp_packet.header_size()) {
klog() << "handle_tcp: IPv4 payload is smaller than TCP header claims (" << ipv4_packet.payload_size() << ", supposedly " << tcp_packet.header_size() << ")";
return;
}
size_t payload_size = ipv4_packet.payload_size() - tcp_packet.header_size();
#ifdef TCP_DEBUG
klog() << "handle_tcp: source=" << ipv4_packet.source().to_string().characters() << ":" << tcp_packet.source_port() << ", destination=" << ipv4_packet.destination().to_string().characters() << ":" << tcp_packet.destination_port() << " seq_no=" << tcp_packet.sequence_number() << ", ack_no=" << tcp_packet.ack_number() << ", flags=" << String::format("%w", tcp_packet.flags()) << " (" << (tcp_packet.has_syn() ? "SYN " : "") << (tcp_packet.has_ack() ? "ACK " : "") << (tcp_packet.has_fin() ? "FIN " : "") << (tcp_packet.has_rst() ? "RST " : "") << "), window_size=" << tcp_packet.window_size() << ", payload_size=" << payload_size;
#endif
auto adapter = NetworkAdapter::from_ipv4_address(ipv4_packet.destination());
if (!adapter) {
klog() << "handle_tcp: this packet is not for me, it's for " << ipv4_packet.destination().to_string().characters();
return;
}
IPv4SocketTuple tuple(ipv4_packet.destination(), tcp_packet.destination_port(), ipv4_packet.source(), tcp_packet.source_port());
#ifdef TCP_DEBUG
klog() << "handle_tcp: looking for socket; tuple=" << tuple.to_string().characters();
#endif
auto socket = TCPSocket::from_tuple(tuple);
if (!socket) {
klog() << "handle_tcp: No TCP socket for tuple " << tuple.to_string().characters();
klog() << "handle_tcp: source=" << ipv4_packet.source().to_string().characters() << ":" << tcp_packet.source_port() << ", destination=" << ipv4_packet.destination().to_string().characters() << ":" << tcp_packet.destination_port() << " seq_no=" << tcp_packet.sequence_number() << ", ack_no=" << tcp_packet.ack_number() << ", flags=" << String::format("%w", tcp_packet.flags()) << " (" << (tcp_packet.has_syn() ? "SYN " : "") << (tcp_packet.has_ack() ? "ACK " : "") << (tcp_packet.has_fin() ? "FIN " : "") << (tcp_packet.has_rst() ? "RST " : "") << "), window_size=" << tcp_packet.window_size() << ", payload_size=" << payload_size;
return;
}
ASSERT(socket->type() == SOCK_STREAM);
ASSERT(socket->local_port() == tcp_packet.destination_port());
#ifdef TCP_DEBUG
klog() << "handle_tcp: got socket; state=" << socket->tuple().to_string().characters() << " " << TCPSocket::to_string(socket->state());
#endif
socket->receive_tcp_packet(tcp_packet, ipv4_packet.payload_size());
switch (socket->state()) {
case TCPSocket::State::Closed:
klog() << "handle_tcp: unexpected flags in Closed state";
// TODO: we may want to send an RST here, maybe as a configurable option
return;
case TCPSocket::State::TimeWait:
klog() << "handle_tcp: unexpected flags in TimeWait state";
(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: {
#ifdef TCP_DEBUG
klog() << "handle_tcp: incoming connection";
#endif
auto& local_address = ipv4_packet.destination();
auto& peer_address = ipv4_packet.source();
auto client = socket->create_client(local_address, tcp_packet.destination_port(), peer_address, tcp_packet.source_port());
if (!client) {
klog() << "handle_tcp: couldn't create client socket";
return;
}
#ifdef TCP_DEBUG
klog() << "handle_tcp: created new client socket with tuple " << client->tuple().to_string().characters();
#endif
client->set_sequence_number(1000);
client->set_ack_number(tcp_packet.sequence_number() + payload_size + 1);
(void)client->send_tcp_packet(TCPFlags::SYN | TCPFlags::ACK);
client->set_state(TCPSocket::State::SynReceived);
return;
}
default:
klog() << "handle_tcp: unexpected flags in Listen state";
// (void)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::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_tcp_packet(TCPFlags::ACK);
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);
(void)socket->send_tcp_packet(TCPFlags::ACK);
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_ack_number(tcp_packet.sequence_number() + payload_size);
(void)socket->send_tcp_packet(TCPFlags::ACK);
socket->set_state(TCPSocket::State::Closed);
socket->set_error(TCPSocket::Error::RSTDuringConnect);
socket->set_setup_state(Socket::SetupState::Completed);
return;
default:
klog() << "handle_tcp: unexpected flags in SynSent state";
(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()) {
klog() << "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:
klog() << "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;
}
return;
default:
klog() << "handle_tcp: unexpected flags in SynReceived state";
(void)socket->send_tcp_packet(TCPFlags::RST);
socket->set_state(TCPSocket::State::Closed);
return;
}
case TCPSocket::State::CloseWait:
switch (tcp_packet.flags()) {
default:
klog() << "handle_tcp: unexpected flags in CloseWait state";
(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:
klog() << "handle_tcp: unexpected flags in LastAck state";
(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);
return;
default:
klog() << "handle_tcp: unexpected flags in FinWait1 state";
(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);
return;
case TCPFlags::ACK | TCPFlags::RST:
socket->set_state(TCPSocket::State::Closed);
return;
default:
klog() << "handle_tcp: unexpected flags in FinWait2 state";
(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:
klog() << "handle_tcp: unexpected flags in Closing state";
(void)socket->send_tcp_packet(TCPFlags::RST);
socket->set_state(TCPSocket::State::Closed);
return;
}
case TCPSocket::State::Established:
if (tcp_packet.has_fin()) {
if (payload_size != 0)
socket->did_receive(ipv4_packet.source(), tcp_packet.source_port(), KBuffer::copy(&ipv4_packet, sizeof(IPv4Packet) + ipv4_packet.payload_size()));
socket->set_ack_number(tcp_packet.sequence_number() + payload_size + 1);
(void)socket->send_tcp_packet(TCPFlags::ACK);
socket->set_state(TCPSocket::State::CloseWait);
socket->set_connected(false);
return;
}
socket->set_ack_number(tcp_packet.sequence_number() + payload_size);
#ifdef TCP_DEBUG
klog() << "Got packet with ack_no=" << tcp_packet.ack_number() << ", seq_no=" << tcp_packet.sequence_number() << ", payload_size=" << payload_size << ", acking it with new ack_no=" << socket->ack_number() << ", seq_no=" << socket->sequence_number();
#endif
if (payload_size) {
if (socket->did_receive(ipv4_packet.source(), tcp_packet.source_port(), KBuffer::copy(&ipv4_packet, sizeof(IPv4Packet) + ipv4_packet.payload_size())))
(void)socket->send_tcp_packet(TCPFlags::ACK);
}
}
}
}
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