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Kernel: Send Fragmented IPv4 packets if payload size > mtu

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This adds IPv4 fragmentation, so now we can send huuuuuuge packets
properly.
This commit is contained in:
AnotherTest 2020-04-02 05:57:49 +04:30 • committed by Andreas Kling
parent 592f218151
commit b3d7c5d9de
3 changed files with 70 additions and 2 deletions
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43
Kernel/Net/NetworkAdapter.cpp
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@ -32,6 +32,7 @@
#include <Kernel/Net/EthernetFrameHeader.h>
#include <Kernel/Net/LoopbackAdapter.h>
#include <Kernel/Net/NetworkAdapter.h>
#include <Kernel/Random.h>
#include <LibBareMetal/StdLib.h>
namespace Kernel {
@ -103,8 +104,8 @@ void NetworkAdapter::send_ipv4(const MACAddress& destination_mac, const IPv4Addr
{
size_t ipv4_packet_size = sizeof(IPv4Packet) + payload_size;
if (ipv4_packet_size > mtu()) {
// FIXME: Implement IP fragmentation.
ASSERT_NOT_REACHED();
send_ipv4_fragmented(destination_mac, destination_ipv4, protocol, payload, payload_size, ttl);
return;
}
size_t ethernet_frame_size = sizeof(EthernetFrameHeader) + sizeof(IPv4Packet) + payload_size;
@ -129,6 +130,44 @@ void NetworkAdapter::send_ipv4(const MACAddress& destination_mac, const IPv4Addr
send_raw((const u8*)&eth, ethernet_frame_size);
}
void NetworkAdapter::send_ipv4_fragmented(const MACAddress& destination_mac, const IPv4Address& destination_ipv4, IPv4Protocol protocol, const u8* payload, size_t payload_size, u8 ttl)
{
// packets must be split on the 64-bit boundary
auto packet_boundary_size = (mtu() - sizeof(IPv4Packet) - sizeof(EthernetFrameHeader)) & 0xfffffff8;
auto fragment_block_count = (payload_size + packet_boundary_size) / packet_boundary_size;
auto last_block_size = payload_size - packet_boundary_size * (fragment_block_count - 1);
auto number_of_blocks_in_fragment = packet_boundary_size / 8;
auto identification = get_good_random<u16>();
size_t ethernet_frame_size = mtu();
for (size_t packet_index = 0; packet_index < fragment_block_count; ++packet_index) {
auto is_last_block = packet_index + 1 == fragment_block_count;
auto packet_payload_size = is_last_block ? last_block_size : packet_boundary_size;
auto buffer = ByteBuffer::create_zeroed(ethernet_frame_size);
auto& eth = *(EthernetFrameHeader*)buffer.data();
eth.set_source(mac_address());
eth.set_destination(destination_mac);
eth.set_ether_type(EtherType::IPv4);
auto& ipv4 = *(IPv4Packet*)eth.payload();
ipv4.set_version(4);
ipv4.set_internet_header_length(5);
ipv4.set_source(ipv4_address());
ipv4.set_destination(destination_ipv4);
ipv4.set_protocol((u8)protocol);
ipv4.set_length(sizeof(IPv4Packet) + packet_payload_size);
ipv4.set_has_more_fragments(!is_last_block);
ipv4.set_ident(identification);
ipv4.set_ttl(ttl);
ipv4.set_fragment_offset(packet_index * number_of_blocks_in_fragment);
ipv4.set_checksum(ipv4.compute_checksum());
m_packets_out++;
m_bytes_out += ethernet_frame_size;
memcpy(ipv4.payload(), payload + packet_index * packet_boundary_size, packet_payload_size);
send_raw((const u8*)&eth, ethernet_frame_size);
}
}
void NetworkAdapter::did_receive(const u8* data, size_t length)
{
InterruptDisabler disabler;