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Fix TCP header length handling

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This commit is contained in:
Baptiste Wicht 2016-09-19 20:14:44 +02:00
parent bb433ba9ba
commit eb98f9f472
1 changed files with 20 additions and 10 deletions
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30
kernel/src/net/tcp_layer.cpp
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@ -65,9 +65,9 @@ network::connection_handler<tcp_connection> connections;
void compute_checksum(network::ethernet::packet& packet) { void compute_checksum(network::ethernet::packet& packet) {
auto* ip_header = reinterpret_cast<network::ip::header*>(packet.payload + packet.tag(1)); auto* ip_header = reinterpret_cast<network::ip::header*>(packet.payload + packet.tag(1));
auto* tcp_header = reinterpret_cast<network::tcp::header*>(packet.payload + packet.index); auto* tcp_header = reinterpret_cast<network::tcp::header*>(packet.payload + packet.tag(2));
auto tcp_len = switch_endian_16(ip_header->total_len) - sizeof(network::ip::header); auto tcp_len = switch_endian_16(ip_header->total_len) - (ip_header->version_ihl & 0xF) * 4;
tcp_header->checksum = 0; tcp_header->checksum = 0;
@ -87,10 +87,12 @@ void compute_checksum(network::ethernet::packet& packet) {
tcp_header->checksum = switch_endian_16(network::checksum_finalize_nz(sum)); tcp_header->checksum = switch_endian_16(network::checksum_finalize_nz(sum));
} }
constexpr size_t default_tcp_header_length = 20;
uint16_t get_default_flags() { uint16_t get_default_flags() {
uint16_t flags = 0; // By default uint16_t flags = 0; // By default
(flag_data_offset(&flags)) = 5; // No options (flag_data_offset(&flags)) = default_tcp_header_length / 4; // No options
return flags; return flags;
} }
@ -106,7 +108,7 @@ void prepare_packet(network::ethernet::packet& packet, size_t source, size_t tar
tcp_header->target_port = switch_endian_16(target); tcp_header->target_port = switch_endian_16(target);
tcp_header->window_size = 1024; tcp_header->window_size = 1024;
packet.index += sizeof(network::tcp::header); packet.index += default_tcp_header_length;
} }
size_t tcp_payload_len(const network::ethernet::packet& packet){ size_t tcp_payload_len(const network::ethernet::packet& packet){
@ -126,7 +128,7 @@ size_t tcp_payload_len(const network::ethernet::packet& packet){
// This is used for raw answer // This is used for raw answer
std::expected<network::ethernet::packet> kernel_prepare_packet(network::interface_descriptor& interface, network::ip::address target_ip, size_t source, size_t target, size_t payload_size) { std::expected<network::ethernet::packet> kernel_prepare_packet(network::interface_descriptor& interface, network::ip::address target_ip, size_t source, size_t target, size_t payload_size) {
// Ask the IP layer to craft a packet // Ask the IP layer to craft a packet
network::ip::packet_descriptor desc{sizeof(network::tcp::header) + payload_size, target_ip, 0x06}; network::ip::packet_descriptor desc{payload_size + default_tcp_header_length, target_ip, 0x06};
auto packet = network::ip::kernel_prepare_packet(interface, desc); auto packet = network::ip::kernel_prepare_packet(interface, desc);
if (packet) { if (packet) {
@ -143,7 +145,7 @@ std::expected<network::ethernet::packet> kernel_prepare_packet(network::interfac
auto server_port = connection.server_port; auto server_port = connection.server_port;
// Ask the IP layer to craft a packet // Ask the IP layer to craft a packet
network::ip::packet_descriptor desc{sizeof(network::tcp::header) + payload_size, target_ip, 0x06}; network::ip::packet_descriptor desc{payload_size + default_tcp_header_length, target_ip, 0x06};
auto packet = network::ip::kernel_prepare_packet(interface, desc); auto packet = network::ip::kernel_prepare_packet(interface, desc);
if (packet) { if (packet) {
@ -160,7 +162,11 @@ std::expected<network::ethernet::packet> kernel_prepare_packet(network::interfac
// finalize without waiting for ACK // finalize without waiting for ACK
std::expected<void> finalize_packet_direct(network::interface_descriptor& interface, network::ethernet::packet& p) { std::expected<void> finalize_packet_direct(network::interface_descriptor& interface, network::ethernet::packet& p) {
p.index -= sizeof(network::tcp::header); auto* tcp_header = reinterpret_cast<network::tcp::header*>(p.payload + p.tag(2));
auto flags = switch_endian_16(tcp_header->flags);
p.index -= *flag_data_offset(&flags) * 4;
// Compute the checksum // Compute the checksum
compute_checksum(p); compute_checksum(p);
@ -224,7 +230,7 @@ void network::tcp::decode(network::interface_descriptor& interface, network::eth
if (*flag_psh(&flags) && connection.socket) { if (*flag_psh(&flags) && connection.socket) {
auto& socket = *connection.socket; auto& socket = *connection.socket;
packet.index += sizeof(header); packet.index += *flag_data_offset(&flags) * 4;
if (socket.listen) { if (socket.listen) {
auto copy = packet; auto copy = packet;
@ -364,7 +370,7 @@ std::expected<network::ethernet::packet> network::tcp::user_prepare_packet(char*
auto& interface = network::select_interface(target_ip); auto& interface = network::select_interface(target_ip);
// Ask the IP layer to craft a packet // Ask the IP layer to craft a packet
network::ip::packet_descriptor desc{sizeof(header) + descriptor->payload_size, target_ip, 0x06}; network::ip::packet_descriptor desc{descriptor->payload_size + default_tcp_header_length, target_ip, 0x06};
auto packet = network::ip::user_prepare_packet(buffer, interface, &desc); auto packet = network::ip::user_prepare_packet(buffer, interface, &desc);
if (packet) { if (packet) {
@ -388,7 +394,11 @@ std::expected<network::ethernet::packet> network::tcp::user_prepare_packet(char*
} }
std::expected<void> network::tcp::finalize_packet(network::interface_descriptor& interface, network::socket& socket, network::ethernet::packet& p) { std::expected<void> network::tcp::finalize_packet(network::interface_descriptor& interface, network::socket& socket, network::ethernet::packet& p) {
p.index -= sizeof(header); auto* tcp_header = reinterpret_cast<network::tcp::header*>(p.payload + p.tag(2));
auto flags = switch_endian_16(tcp_header->flags);
p.index -= *flag_data_offset(&flags) * 4;
// Compute the checksum // Compute the checksum
compute_checksum(p); compute_checksum(p);