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udp.c File Reference

UDP (User Datagram Protocol) layer. More...

#include <const.h>
#include <errno.h>
#include <kernel/console.h>
#include <net/ip.h>
#include <net/network.h>
#include <net/udp.h>

Go to the source code of this file.

Functions
uint16_t	udp_checksum (const void *buff, size_t len, in_addr_t src_addr, in_addr_t dest_addr)
	Calculate the UDP checksum (calculated with the whole packet). Parameters: buff  The UDP packet. len  The UDP packet length. src_addr  The IP source address (in network format). dest_addr  The IP destination address (in network format). Returns: The result of the checksum.
void	to_udp_layer (udp_t *packet, in_addr_t ip_src, in_addr_t ip_dst)
	Process an UDP packet received from the IP layer. Parameters: packet  The UDP packet. ip_src  The IP source address (in network format). ip_dst  The IP destination address (in network format).
int	recv_udp_packet (udp_t *buf, size_t len, int flags)
	Receive an UDP packet. Parameters: buf  The buffer where the received packet will be copied. len  The maximum size of the buffer. flags  Flags. Returns: The size of the packet received in bytes.

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Detailed Description

UDP (User Datagram Protocol) layer.

Author:

Andrea Righi <drizzt@inwind.it>

Date:

Last update:
2003-01-21 Andrea Righi: Suppressed deferencing type-punned pointer warning.

Note:

Copyright (©) 2003 Andrea Righi

Definition in file udp.c.

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Function Documentation

int recv_udp_packet (  udp_t *    buf, size_t    len, int    flags )

Receive an UDP packet. Parameters: buf  The buffer where the received packet will be copied. len  The maximum size of the buffer. flags  Flags. Returns: The size of the packet received in bytes. Todo: Routine not implemented! For now return protocol not available error. Definition at line 132 of file udp.c. { return( -ENOPROTOOPT ); }

void to_udp_layer (  udp_t *    packet, in_addr_t    ip_src, in_addr_t    ip_dst )

Process an UDP packet received from the IP layer. Parameters: packet  The UDP packet. ip_src  The IP source address (in network format). ip_dst  The IP destination address (in network format). Definition at line 73 of file udp.c. { int i; bool chk; uint16_t len = ntohs(packet->udp_len) - sizeof(udp_t); // For UDP packets the checksum is optional; a value of 0 in // // the checksum means the checksum is not used. A value of // // 0xFFFF means the checksum is used and its value is 0. // if ( packet->udp_chk != 0 ) { // The checksum is used // if ( packet->udp_chk == 0xFFFF ) packet->udp_chk = 0x0000; // Calculate the checksum // chk = udp_checksum( packet, ntohs(packet->udp_len), ip_src, ip_dst ); if ( chk ) { kprintf("\n\rUDP checksum error! %04X", chk); return; } } // Dump the UDP packet // kprintf( "\n\rUDP packet received (%u bytes of data)" "\n\rsender = %u.%u.%u.%u:%u" "\n\rreceiver= %u.%u.%u.%u:%u", len, IP_A(ntohl(ip_src)), IP_B(ntohl(ip_src)), IP_C(ntohl(ip_src)), IP_D(ntohl(ip_src)), ntohs(packet->udp_src), IP_A(ntohl(ip_dst)), IP_B(ntohl(ip_dst)), IP_C(ntohl(ip_dst)), IP_D(ntohl(ip_dst)), ntohs(packet->udp_dst) ); kprintf("\n\rData:\n\r"); for(i=0; i<len; i++) kputchar( (((uint8_t *)packet)+sizeof(udp_t))[i] ); }

uint16_t udp_checksum (  const void *    buff, size_t    len, in_addr_t    src_addr, in_addr_t    dest_addr )

Calculate the UDP checksum (calculated with the whole packet). Parameters: buff  The UDP packet. len  The UDP packet length. src_addr  The IP source address (in network format). dest_addr  The IP destination address (in network format). Returns: The result of the checksum. Definition at line 29 of file udp.c. { const uint16_t *buf=buff; uint16_t *ip_src=(void *)&src_addr, *ip_dst=(void *)&dest_addr; uint32_t sum; size_t length=len; // Calculate the sum // sum = 0; while (len > 1) { sum += *buf++; if (sum & 0x80000000) sum = (sum & 0xFFFF) + (sum >> 16); len -= 2; } if ( len & 1 ) // Add the padding if the packet lenght is odd // sum += *((uint8_t *)buf); // Add the pseudo-header // sum += *(ip_src++); sum += *ip_src; sum += *(ip_dst++); sum += *ip_dst; sum += htons(IPPROTO_UDP); sum += htons(length); // Add the carries // while (sum >> 16) sum = (sum & 0xFFFF) + (sum >> 16); // Return the one's complement of sum // return ( (uint16_t)(~sum) ); }

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