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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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15
Kernel/Net/NetworkTask.cpp
View file

@ -246,8 +246,14 @@ void handle_icmp(const EthernetFrameHeader& eth, const IPv4Packet& ipv4_packet,
dbgln("handle_icmp: EchoRequest packet is too small, ignoring.");
return;
}
auto buffer = ByteBuffer::create_zeroed(icmp_packet_size);
auto& response = *(ICMPEchoPacket*)buffer.data();
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, 64);
auto& response = *(ICMPEchoPacket*)(packet->buffer.data() + ipv4_payload_offset);
response.header.set_type(ICMPType::EchoReply);
response.header.set_code(0);
response.identifier = request.identifier;
@ -256,9 +262,8 @@ void handle_icmp(const EthernetFrameHeader& eth, const IPv4Packet& ipv4_packet,
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);
[[maybe_unused]] auto result = adapter->send_ipv4(adapter->ipv4_address(), eth.source(),
ipv4_packet.source(), IPv4Protocol::ICMP, response_buffer, buffer.size(), 64);
adapter->send_raw({ packet->buffer.data(), packet->buffer.size() });
adapter->release_packet_buffer(*packet);
}
}