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Prepare DNS encoding

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This commit is contained in:
Baptiste Wicht 2016-09-11 11:21:32 +02:00
parent 3eef5e0699
commit f4e5c43bf9
2 changed files with 58 additions and 0 deletions
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4
kernel/include/net/dns_layer.hpp
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@ -42,6 +42,10 @@ struct header {
void decode(network::interface_descriptor& interface, network::ethernet::packet& packet); void decode(network::interface_descriptor& interface, network::ethernet::packet& packet);
std::expected<network::ethernet::packet> prepare_packet_query(network::interface_descriptor& interface, network::ip::address target_ip, uint16_t source_port, uint16_t identification, size_t payload_size);
std::expected<network::ethernet::packet> prepare_packet_query(char* buffer, network::interface_descriptor& interface, network::ip::address target_ip, uint16_t source_port, uint16_t identification, size_t payload_size);
void finalize_packet(network::interface_descriptor& interface, network::ethernet::packet& p);
} // end of dns namespace } // end of dns namespace
} // end of network namespace } // end of network namespace

54
kernel/src/net/dns_layer.cpp
View File

@ -6,11 +6,38 @@
//======================================================================= //=======================================================================
#include "net/dns_layer.hpp" #include "net/dns_layer.hpp"
#include "net/udp_layer.hpp"
#include "kernel_utils.hpp" #include "kernel_utils.hpp"
namespace { namespace {
void prepare_packet_query(network::ethernet::packet& packet, uint16_t identification){
// Set the DNS header
auto* dns_header = reinterpret_cast<network::dns::header*>(packet.payload + packet.index);
// Set the identification
dns_header->identification = switch_endian_16(identification);
// There is one question, nothing else
dns_header->questions = switch_endian_16(1);
dns_header->answers = switch_endian_16(0);
dns_header->authority_rrs = switch_endian_16(0);
dns_header->additional_rrs = switch_endian_16(0);
// Set all the flags
dns_header->flags.qr = 0; // This is a query
dns_header->flags.opcode = 0; // This is a standard query
dns_header->flags.aa = 0; // This is a query (field not used)
dns_header->flags.tc = 0; // The question is not truncated
dns_header->flags.rd = 0; // No need for recursion
dns_header->flags.ra = 0; // This is a query (field not used)
dns_header->flags.zeroes = 0; // Always zero
dns_header->flags.rcode = 0; // This is a query (field not used)
packet.index += sizeof(network::dns::header);
}
} //end of anonymous namespace } //end of anonymous namespace
@ -39,3 +66,30 @@ void network::dns::decode(network::interface_descriptor& /*interface*/, network:
//TODO //TODO
} }
std::expected<network::ethernet::packet> network::dns::prepare_packet_query(network::interface_descriptor& interface, network::ip::address target_ip, uint16_t source_port, uint16_t identification, size_t payload_size){
// Ask the UDP layer to craft a packet
auto packet = network::udp::prepare_packet(interface, target_ip, source_port, 53, sizeof(header) + payload_size);
if(packet){
::prepare_packet_query(*packet, identification);
}
return packet;
}
std::expected<network::ethernet::packet> network::dns::prepare_packet_query(char* buffer, network::interface_descriptor& interface, network::ip::address target_ip, uint16_t source_port, uint16_t identification, size_t payload_size){
// Ask the UDP layer to craft a packet
auto packet = network::udp::prepare_packet(buffer, interface, target_ip, source_port, 53, sizeof(header) + payload_size);
if(packet){
::prepare_packet_query(*packet, identification);
}
return packet;
}
void network::dns::finalize_packet(network::interface_descriptor& interface, network::ethernet::packet& p){
// Give the packet to the UDP layer for finalization
network::udp::finalize_packet(interface, p);
}