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Kernel: Avoid allocations when sending IP packets

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Previously we'd allocate buffers when sending packets. This patch
avoids these allocations by using the NetworkAdapter's packet queue.

At the same time this also avoids copying partially constructed
packets in order to prepend Ethernet and/or IPv4 headers. It also
properly truncates UDP and raw IP packets.
This commit is contained in:
Gunnar Beutner 2021-05-26 05:35:05 +02:00 • committed by Andreas Kling
parent f8310b7796
commit b436dd138b
7 changed files with 94 additions and 117 deletions
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20
Kernel/Net/UDPSocket.cpp
View file

@ -78,19 +78,23 @@ KResultOr<size_t> UDPSocket::protocol_send(const UserOrKernelBuffer& data, size_
auto routing_decision = route_to(peer_address(), local_address(), bound_interface());
if (routing_decision.is_zero())
return EHOSTUNREACH;
const size_t buffer_size = sizeof(UDPPacket) + data_length;
auto buffer = ByteBuffer::create_zeroed(buffer_size);
auto& udp_packet = *reinterpret_cast<UDPPacket*>(buffer.data());
auto ipv4_payload_offset = routing_decision.adapter->ipv4_payload_offset();
data_length = min(data_length, routing_decision.adapter->mtu() - ipv4_payload_offset - sizeof(UDPPacket));
const size_t udp_buffer_size = sizeof(UDPPacket) + data_length;
auto packet = routing_decision.adapter->acquire_packet_buffer(ipv4_payload_offset + udp_buffer_size);
if (!packet)
return ENOMEM;
memset(packet->buffer.data() + ipv4_payload_offset, 0, sizeof(UDPPacket));
auto& udp_packet = *reinterpret_cast<UDPPacket*>(packet->buffer.data() + ipv4_payload_offset);
udp_packet.set_source_port(local_port());
udp_packet.set_destination_port(peer_port());
udp_packet.set_length(buffer_size);
udp_packet.set_length(udp_buffer_size);
if (!data.read(udp_packet.payload(), data_length))
return EFAULT;
auto result = routing_decision.adapter->send_ipv4(local_address(), routing_decision.next_hop,
peer_address(), IPv4Protocol::UDP, UserOrKernelBuffer::for_kernel_buffer(buffer.data()), buffer_size, ttl());
if (result.is_error())
return result;
routing_decision.adapter->fill_in_ipv4_header(*packet, local_address(), routing_decision.next_hop,
peer_address(), IPv4Protocol::UDP, udp_buffer_size, ttl());
routing_decision.adapter->send_raw({ packet->buffer.data(), packet->buffer.size() });
return data_length;
}