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#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <byteswap.h>
#include <ipxe/iobuf.h>
#include <ipxe/tables.h>
#include <ipxe/ipstat.h>
#include <ipxe/netdevice.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 netdev Network device
* @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
* @v stats IP statistics
* @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, struct net_device *netdev,
uint8_t tcpip_proto, struct sockaddr_tcpip *st_src,
struct sockaddr_tcpip *st_dest, uint16_t pshdr_csum,
struct ip_statistics *stats ) {
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 );
stats->in_delivers++;
return tcpip->rx ( iobuf, netdev, st_src, st_dest,
pshdr_csum );
}
}
DBG ( "Unrecognised TCP/IP protocol %d\n", tcpip_proto );
stats->in_unknown_protos++;
free_iob ( iobuf );
return -EPROTONOSUPPORT;
}
/**
* Find TCP/IP network-layer protocol
*
* @v st_dest Destination address
* @ret tcpip_net TCP/IP network-layer protocol, or NULL if not found
*/
static struct tcpip_net_protocol *
tcpip_net_protocol ( struct sockaddr_tcpip *st_dest ) {
struct tcpip_net_protocol *tcpip_net;
for_each_table_entry ( tcpip_net, TCPIP_NET_PROTOCOLS ) {
if ( tcpip_net->sa_family == st_dest->st_family )
return tcpip_net;
}
DBG ( "Unrecognised TCP/IP address family %d\n", st_dest->st_family );
return NULL;
}
/**
* 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 */
tcpip_net = tcpip_net_protocol ( st_dest );
if ( tcpip_net ) {
DBG ( "TCP/IP sending %s packet\n", tcpip_net->name );
return tcpip_net->tx ( iobuf, tcpip_protocol, st_src, st_dest,
netdev, trans_csum );
}
free_iob ( iobuf );
return -EAFNOSUPPORT;
}
/**
* Determine transmitting network device
*
* @v st_dest Destination address
* @ret netdev Network device, or NULL
*/
struct net_device * tcpip_netdev ( struct sockaddr_tcpip *st_dest ) {
struct tcpip_net_protocol *tcpip_net;
/* Hand off to the appropriate network-layer protocol */
tcpip_net = tcpip_net_protocol ( st_dest );
if ( tcpip_net )
return tcpip_net->netdev ( st_dest );
return NULL;
}
/**
* Determine maximum transmission unit
*
* @v st_dest Destination address
* @ret mtu Maximum transmission unit
*/
size_t tcpip_mtu ( struct sockaddr_tcpip *st_dest ) {
struct tcpip_net_protocol *tcpip_net;
struct net_device *netdev;
size_t mtu;
/* Find appropriate network-layer protocol */
tcpip_net = tcpip_net_protocol ( st_dest );
if ( ! tcpip_net )
return 0;
/* Find transmitting network device */
netdev = tcpip_net->netdev ( st_dest );
if ( ! netdev )
return 0;
/* Calculate MTU */
mtu = ( netdev->max_pkt_len - netdev->ll_protocol->ll_header_len -
tcpip_net->header_len );
return mtu;
}
/**
* 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 );
}
/**
* Bind to local TCP/IP port
*
* @v st_local Local TCP/IP socket address, or NULL
* @v available Function to check port availability
* @ret port Local port number, or negative error
*/
int tcpip_bind ( struct sockaddr_tcpip *st_local,
int ( * available ) ( int port ) ) {
uint16_t flags = 0;
uint16_t try_port = 0;
uint16_t min_port;
uint16_t max_port;
unsigned int offset;
unsigned int i;
/* Extract parameters from local socket address */
if ( st_local ) {
flags = st_local->st_flags;
try_port = ntohs ( st_local->st_port );
}
/* If an explicit port is specified, check its availability */
if ( try_port )
return available ( try_port );
/* Otherwise, find an available port in the range [1,1023] or
* [1025,65535] as appropriate.
*/
min_port = ( ( ( ! flags ) & TCPIP_BIND_PRIVILEGED ) + 1 );
max_port = ( ( flags & TCPIP_BIND_PRIVILEGED ) - 1 );
offset = random();
for ( i = 0 ; i <= max_port ; i++ ) {
try_port = ( ( i + offset ) & max_port );
if ( try_port < min_port )
continue;
if ( available ( try_port ) < 0 )
continue;
return try_port;
}
return -EADDRINUSE;
}
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