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#include <stdint.h>
#include <string.h>
#include <errno.h>
#include <byteswap.h>
#include <ipxe/iobuf.h>
#include <ipxe/tables.h>
#include <ipxe/tcpip.h>
/** @file
*
* Transport-network layer interface
*
* This file contains functions and utilities for the
* TCP/IP transport-network layer interface
*/
FILE_LICENCE ( GPL2_OR_LATER );
/** Process a received TCP/IP packet
*
* @v iobuf I/O buffer
* @v tcpip_proto Transport-layer protocol number
* @v st_src Partially-filled source address
* @v st_dest Partially-filled destination address
* @v pshdr_csum Pseudo-header checksum
* @ret rc Return status code
*
* This function expects a transport-layer segment from the network
* layer. The network layer should fill in as much as it can of the
* source and destination addresses (i.e. it should fill in the
* address family and the network-layer addresses, but leave the ports
* and the rest of the structures as zero).
*/
int tcpip_rx ( struct io_buffer *iobuf, uint8_t tcpip_proto,
struct sockaddr_tcpip *st_src,
struct sockaddr_tcpip *st_dest,
uint16_t pshdr_csum ) {
struct tcpip_protocol *tcpip;
/* Hand off packet to the appropriate transport-layer protocol */
for_each_table_entry ( tcpip, TCPIP_PROTOCOLS ) {
if ( tcpip->tcpip_proto == tcpip_proto ) {
DBG ( "TCP/IP received %s packet\n", tcpip->name );
return tcpip->rx ( iobuf, st_src, st_dest, pshdr_csum );
}
}
DBG ( "Unrecognised TCP/IP protocol %d\n", tcpip_proto );
free_iob ( iobuf );
return -EPROTONOSUPPORT;
}
/** Transmit a TCP/IP packet
*
* @v iobuf I/O buffer
* @v tcpip_protocol Transport-layer protocol
* @v st_src Source address, or NULL to use route default
* @v st_dest Destination address
* @v netdev Network device to use if no route found, or NULL
* @v trans_csum Transport-layer checksum to complete, or NULL
* @ret rc Return status code
*/
int tcpip_tx ( struct io_buffer *iobuf, struct tcpip_protocol *tcpip_protocol,
struct sockaddr_tcpip *st_src, struct sockaddr_tcpip *st_dest,
struct net_device *netdev, uint16_t *trans_csum ) {
struct tcpip_net_protocol *tcpip_net;
/* Hand off packet to the appropriate network-layer protocol */
for_each_table_entry ( tcpip_net, TCPIP_NET_PROTOCOLS ) {
if ( tcpip_net->sa_family == st_dest->st_family ) {
DBG ( "TCP/IP sending %s packet\n", tcpip_net->name );
return tcpip_net->tx ( iobuf, tcpip_protocol, st_src,
st_dest, netdev, trans_csum );
}
}
DBG ( "Unrecognised TCP/IP address family %d\n", st_dest->st_family );
free_iob ( iobuf );
return -EAFNOSUPPORT;
}
/**
* Calculate continued TCP/IP checkum
*
* @v partial Checksum of already-summed data, in network byte order
* @v data Data buffer
* @v len Length of data buffer
* @ret cksum Updated checksum, in network byte order
*
* Calculates a TCP/IP-style 16-bit checksum over the data block. The
* checksum is returned in network byte order.
*
* This function may be used to add new data to an existing checksum.
* The function assumes that both the old data and the new data start
* on even byte offsets; if this is not the case then you will need to
* byte-swap either the input partial checksum, the output checksum,
* or both. Deciding which to swap is left as an exercise for the
* interested reader.
*/
uint16_t generic_tcpip_continue_chksum ( uint16_t partial,
const void *data, size_t len ) {
unsigned int cksum = ( ( ~partial ) & 0xffff );
unsigned int value;
unsigned int i;
for ( i = 0 ; i < len ; i++ ) {
value = * ( ( uint8_t * ) data + i );
if ( i & 1 ) {
/* Odd bytes: swap on little-endian systems */
value = be16_to_cpu ( value );
} else {
/* Even bytes: swap on big-endian systems */
value = le16_to_cpu ( value );
}
cksum += value;
if ( cksum > 0xffff )
cksum -= 0xffff;
}
return ( ~cksum );
}
/**
* Calculate TCP/IP checkum
*
* @v data Data buffer
* @v len Length of data buffer
* @ret cksum Checksum, in network byte order
*
* Calculates a TCP/IP-style 16-bit checksum over the data block. The
* checksum is returned in network byte order.
*/
uint16_t tcpip_chksum ( const void *data, size_t len ) {
return tcpip_continue_chksum ( TCPIP_EMPTY_CSUM, data, len );
}
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