/* * \brief User datagram protocol. * \author Stefan Kalkowski * \date 2010-08-19 */ /* * Copyright (C) 2010-2013 Genode Labs GmbH * * This file is part of the Genode OS framework, which is distributed * under the terms of the GNU General Public License version 2. */ #ifndef _UDP_H_ #define _UDP_H_ /* Genode */ #include #include #include #include #include namespace Net { class Udp_packet; } /** * Data layout of this class conforms to an UDP packet (RFC 768) * * UDP-header-format: * * ----------------------------------------------------------------------- * | source-port | destination-port | length | checksum | * | 2 bytes | 2 bytes | 2 bytes | 2 bytes | * ----------------------------------------------------------------------- */ class Net::Udp_packet { private: /*********************** ** UDP header fields ** ***********************/ Genode::uint16_t _src_port; Genode::uint16_t _dst_port; Genode::uint16_t _length; Genode::uint16_t _checksum; unsigned _data[0]; public: enum Protocol_id { IP_ID = 0x11 }; /** * Exception used to indicate protocol violation. */ class No_udp_packet : Genode::Exception {}; /***************** ** Constructor ** *****************/ Udp_packet(Genode::size_t size) { /* Udp header needs to fit in */ if (size < sizeof(Udp_packet)) throw No_udp_packet(); } /****************************** ** UDP field read-accessors ** ******************************/ Genode::uint16_t src_port() { return host_to_big_endian(_src_port); } Genode::uint16_t dst_port() { return host_to_big_endian(_dst_port); } Genode::uint16_t length() { return host_to_big_endian(_length); } Genode::uint16_t checksum() { return host_to_big_endian(_checksum); } template T * data() { return (T *)(_data); } template T const * data() const { return (T const *)(_data); } /*************** ** Operators ** ***************/ /** * Placement new. */ void * operator new(Genode::size_t size, void* addr) { return addr; } /*************************** ** Convenience functions ** ***************************/ /** * UDP checksum is calculated over the udp datagram + an IPv4 * pseudo header. * * IPv4 pseudo header: * * -------------------------------------------------------------- * | src-ipaddr | dst-ipaddr | zero-field | prot.-id | udp-length | * | 4 bytes | 4 bytes | 1 byte | 1 byte | 2 bytes | * -------------------------------------------------------------- */ void calc_checksum(Ipv4_packet::Ipv4_address src, Ipv4_packet::Ipv4_address dst) { /* have to reset the checksum field for calculation */ _checksum = 0; /* * sum up pseudo header */ Genode::uint32_t sum = 0; for (unsigned i = 0; i < Ipv4_packet::ADDR_LEN; i=i+2) { Genode::uint16_t s = src.addr[i] << 8 | src.addr[i + 1]; Genode::uint16_t d = dst.addr[i] << 8 | dst.addr[i + 1]; sum += s + d; } Genode::uint8_t prot[] = { 0, IP_ID }; sum += host_to_big_endian(*(Genode::uint16_t*)&prot) + length(); /* * sum up udp packet itself */ unsigned max = (length() & 1) ? (length() - 1) : length(); Genode::uint16_t *udp = (Genode::uint16_t*) this; for (unsigned i = 0; i < max; i=i+2) sum += host_to_big_endian(*udp++); /* if udp length is odd, append a zero byte */ if (length() & 1) { Genode::uint8_t last[] = { *((Genode::uint8_t*)this + (length()-1)), 0 }; sum += host_to_big_endian(*(Genode::uint16_t*)&last); } /* * keep only the last 16 bits of the 32 bit calculated sum * and add the carries */ while (sum >> 16) sum = (sum & 0xffff) + (sum >> 16); /* one's complement of sum */ _checksum = host_to_big_endian((Genode::uint16_t) ~sum); } } __attribute__((packed)); #endif /* _UDP_H_ */