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Kernel: Fix up the ICMP implementation to generate correct Echo replies.

Browse source 
Serenity now responds to ping. :^)
This commit is contained in:
Andreas Kling 2019-03-12 11:44:38 +01:00
parent 75e0ddd46a
commit 9858be636f
5 changed files with 66 additions and 28 deletions
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32
Kernel/NetworkTask.cpp
View file

@ -36,7 +36,7 @@ void NetworkTask_main()
sleep(100);
continue;
}
if (packet.size() < (int)(sizeof(EthernetFrameHeader) + sizeof(EthernetFrameCheckSequence))) {
if (packet.size() < (int)(sizeof(EthernetFrameHeader))) {
kprintf("NetworkTask: Packet is too small to be an Ethernet packet! (%d)\n", packet.size());
continue;
}
@ -63,7 +63,7 @@ void NetworkTask_main()
void handle_arp(const EthernetFrameHeader& eth, int frame_size)
{
constexpr int minimum_arp_frame_size = sizeof(EthernetFrameHeader) + sizeof(ARPPacket) + sizeof(EthernetFrameCheckSequence);
constexpr int minimum_arp_frame_size = sizeof(EthernetFrameHeader) + sizeof(ARPPacket);
if (frame_size < minimum_arp_frame_size) {
kprintf("handle_arp: Frame too small (%d, need %d)\n", frame_size, minimum_arp_frame_size);
return;
@ -131,7 +131,7 @@ void handle_arp(const EthernetFrameHeader& eth, int frame_size)
void handle_ipv4(const EthernetFrameHeader& eth, int frame_size)
{
constexpr int minimum_ipv4_frame_size = sizeof(EthernetFrameHeader) + sizeof(IPv4Packet) + sizeof(EthernetFrameCheckSequence);
constexpr int minimum_ipv4_frame_size = sizeof(EthernetFrameHeader) + sizeof(IPv4Packet);
if (frame_size < minimum_ipv4_frame_size) {
kprintf("handle_ipv4: Frame too small (%d, need %d)\n", frame_size, minimum_ipv4_frame_size);
return;
@ -159,14 +159,23 @@ void handle_icmp(const EthernetFrameHeader& eth, int frame_size)
(void)frame_size;
auto& ipv4_packet = *static_cast<const IPv4Packet*>(eth.payload());
auto& icmp_header = *static_cast<const ICMPHeader*>(ipv4_packet.payload());
kprintf("handle_icmp: type=%b, code=%b\n", icmp_header.type(), icmp_header.code());
#ifdef ICMP_DEBUG
kprintf("handle_icmp: source=%s, destination=%d type=%b, code=%b\n",
ipv4_packet.source().to_string().characters(),
ipv4_packet.destination().to_string().characters(),
icmp_header.type(),
icmp_header.code()
);
#endif
auto& e1000 = *E1000NetworkAdapter::the();
if (ipv4_packet.destination() == e1000.ipv4_address()) {
// It's for me!
if (icmp_header.type() == ICMPType::EchoRequest) {
auto& request = reinterpret_cast<const ICMPEchoPacket&>(icmp_header);
kprintf("ICMP echo request: id=%u, seq=%u, len=%u\n", (int)request.identifier, (int)request.sequence_number, ipv4_packet.length() - sizeof(ICMPEchoPacket));
kprintf("handle_icmp: EchoRequest from %s: id=%u, seq=%u\n",
ipv4_packet.source().to_string().characters(),
(word)request.identifier,
(word)request.sequence_number
);
byte* response_buffer = (byte*)kmalloc(ipv4_packet.length());
memset(response_buffer, 0, ipv4_packet.length());
struct [[gnu::packed]] EchoResponse {
@ -180,11 +189,18 @@ void handle_icmp(const EthernetFrameHeader& eth, int frame_size)
response.ipv4.set_destination(ipv4_packet.source());
response.ipv4.set_protocol(IPv4Protocol::ICMP);
response.ipv4.set_length(ipv4_packet.length());
response.ipv4.set_ident(1);
response.ipv4.set_ttl(64);
response.ipv4.set_checksum(response.ipv4.compute_checksum());
response.icmp_echo.header.set_type(ICMPType::EchoReply);
response.icmp_echo.header.set_code(0);
response.icmp_echo.identifier = request.identifier;
response.icmp_echo.sequence_number = request.sequence_number;
memcpy(response.icmp_echo.payload(), request.payload(), ipv4_packet.length() - sizeof(EchoResponse));
size_t icmp_packet_length = ipv4_packet.length() - sizeof(IPv4Packet);
size_t icmp_payload_length = ipv4_packet.length() - sizeof(EchoResponse);
memcpy(response.icmp_echo.payload(), request.payload(), icmp_payload_length);
response.icmp_echo.header.set_checksum(internet_checksum(&response.icmp_echo, icmp_packet_length));
e1000.send_ipv4(eth.source(), response_buffer, ipv4_packet.length());
kfree(response_buffer);
}