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Better handling of variable IP header length

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This commit is contained in:
Baptiste Wicht 2016-09-19 19:59:48 +02:00
parent 26abd1fd6a
commit 4afeb82c4e
1 changed files with 16 additions and 14 deletions
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30
kernel/src/net/ip_layer.cpp
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@ -42,14 +42,16 @@ void compute_checksum(network::ip::header* header){
header->header_checksum = ~uint16_t(value);
}
constexpr size_t default_ip_header_len = 20;
void prepare_packet(network::ethernet::packet& packet, network::interface_descriptor& interface, size_t size, network::ip::address target_ip, size_t protocol){
packet.tag(1, packet.index);
auto* ip_header = reinterpret_cast<network::ip::header*>(packet.payload + packet.index);
ip_header->version_ihl = (4 << 4) + 5;
ip_header->version_ihl = (4 << 4) + default_ip_header_len / 4;
ip_header->dscp_ecn = 0;
ip_header->total_len = switch_endian_16(uint16_t(size) + sizeof(network::ip::header));
ip_header->total_len = switch_endian_16(uint16_t(size) + default_ip_header_len);
ip_header->identification = 0;
ip_header->flags_offset = 0;
ip_header->flags_offset = switch_endian_16(uint16_t(1) << 14);
@ -60,7 +62,7 @@ void prepare_packet(network::ethernet::packet& packet, network::interface_descri
compute_checksum(ip_header);
packet.index += sizeof(network::ip::header);
packet.index += default_ip_header_len;
}
std::expected<uint64_t> get_target_mac(network::interface_descriptor& interface, network::ip::address target_ip){
@ -122,9 +124,9 @@ void network::ip::decode(network::interface_descriptor& interface, network::ethe
return;
}
auto ihl = ip_header->version_ihl & 0xF;
auto length = switch_endian_16(ip_header->total_len);
auto data_length = length - ihl * 4;
const auto header_length = ip_header->version_ihl & 0xF;
auto length = switch_endian_16(ip_header->total_len);
auto data_length = length - header_length * 4;
logging::logf(logging::log_level::TRACE, "ip: Data Length: %u\n", size_t(data_length));
logging::logf(logging::log_level::TRACE, "ip: Time To Live: %u\n", size_t(ip_header->ttl));
@ -133,19 +135,19 @@ void network::ip::decode(network::interface_descriptor& interface, network::ethe
auto target = ip32_to_ip(ip_header->target_ip);
logging::logf(logging::log_level::TRACE, "ip: Source Protocol Address %u.%u.%u.%u \n",
uint64_t(source(0)), uint64_t(source(1)), uint64_t(source(2)), uint64_t(source(3)));
uint64_t(source(0)), uint64_t(source(1)), uint64_t(source(2)), uint64_t(source(3)));
logging::logf(logging::log_level::TRACE, "ip: Target Protocol Address %u.%u.%u.%u \n",
uint64_t(target(0)), uint64_t(target(1)), uint64_t(target(2)), uint64_t(target(3)));
uint64_t(target(0)), uint64_t(target(1)), uint64_t(target(2)), uint64_t(target(3)));
auto protocol = ip_header->protocol;
packet.index += sizeof(header);
packet.index += header_length;
if(protocol == 0x01){
if (protocol == 0x01) {
network::icmp::decode(interface, packet);
} else if(protocol == 0x06){
} else if (protocol == 0x06) {
network::tcp::decode(interface, packet);
} else if(protocol == 0x11){
} else if (protocol == 0x11) {
network::udp::decode(interface, packet);
} else {
logging::logf(logging::log_level::ERROR, "ip: Packet of unknown protocol detected (%h)\n", size_t(protocol));
@ -160,7 +162,7 @@ std::expected<network::ethernet::packet> network::ip::kernel_prepare_packet(netw
}
// Ask the ethernet layer to craft a packet
network::ethernet::packet_descriptor desc{descriptor.size + sizeof(header), *target_mac, ethernet::ether_type::IPV4};
network::ethernet::packet_descriptor desc{descriptor.size + default_ip_header_len, *target_mac, ethernet::ether_type::IPV4};
auto packet = network::ethernet::kernel_prepare_packet(interface, desc);
if(packet){
@ -178,7 +180,7 @@ std::expected<network::ethernet::packet> network::ip::user_prepare_packet(char*
}
// Ask the ethernet layer to craft a packet
network::ethernet::packet_descriptor desc{descriptor->size + sizeof(header), *target_mac, ethernet::ether_type::IPV4};
network::ethernet::packet_descriptor desc{descriptor->size + default_ip_header_len, *target_mac, ethernet::ether_type::IPV4};
auto packet = network::ethernet::user_prepare_packet(buffer, interface, &desc);
if(packet){