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[icmp] Add support for responding to pings
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Michael Brown committed Feb 17, 2009
1 parent dbbd81c commit 06b5132
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Showing 4 changed files with 128 additions and 0 deletions.
1 change: 1 addition & 0 deletions src/include/gpxe/errfile.h
Expand Up @@ -139,6 +139,7 @@
#define ERRFILE_slam ( ERRFILE_NET | 0x00160000 )
#define ERRFILE_ib_sma ( ERRFILE_NET | 0x00170000 )
#define ERRFILE_ib_packet ( ERRFILE_NET | 0x00180000 )
#define ERRFILE_icmp ( ERRFILE_NET | 0x00190000 )

#define ERRFILE_image ( ERRFILE_IMAGE | 0x00000000 )
#define ERRFILE_elf ( ERRFILE_IMAGE | 0x00010000 )
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23 changes: 23 additions & 0 deletions src/include/gpxe/icmp.h
@@ -0,0 +1,23 @@
#ifndef _GPXE_ICMP_H
#define _GPXE_ICMP_H

/** @file
*
* ICMP protocol
*
*/

/** An ICMP header */
struct icmp_header {
/** Type */
uint8_t type;
/** Code */
uint8_t code;
/** Checksum */
uint16_t chksum;
} __attribute__ (( packed ));

#define ICMP_ECHO_RESPONSE 0
#define ICMP_ECHO_REQUEST 8

#endif /* _GPXE_ICMP_H */
101 changes: 101 additions & 0 deletions src/net/icmp.c
@@ -0,0 +1,101 @@
/*
* Copyright (C) 2009 Michael Brown <mbrown@fensystems.co.uk>.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of the
* License, or any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#include <string.h>
#include <errno.h>
#include <gpxe/iobuf.h>
#include <gpxe/in.h>
#include <gpxe/tcpip.h>
#include <gpxe/icmp.h>

/** @file
*
* ICMP protocol
*
*/

struct tcpip_protocol icmp_protocol __tcpip_protocol;

/**
* Process a received packet
*
* @v iobuf I/O buffer
* @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
*/
static int icmp_rx ( struct io_buffer *iobuf, struct sockaddr_tcpip *st_src,
struct sockaddr_tcpip *st_dest,
uint16_t pshdr_csum __unused ) {
struct icmp_header *icmp = iobuf->data;
size_t len = iob_len ( iobuf );
unsigned int csum;
int rc;

/* Sanity check */
if ( len < sizeof ( *icmp ) ) {
DBG ( "ICMP packet too short at %zd bytes (min %zd bytes)\n",
len, sizeof ( *icmp ) );
rc = -EINVAL;
goto done;
}

/* Verify checksum */
csum = tcpip_chksum ( icmp, len );
if ( csum != 0 ) {
DBG ( "ICMP checksum incorrect (is %04x, should be 0000)\n",
csum );
DBG_HD ( icmp, len );
rc = -EINVAL;
goto done;
}

/* We respond only to pings */
if ( icmp->type != ICMP_ECHO_REQUEST ) {
DBG ( "ICMP ignoring type %d\n", icmp->type );
rc = 0;
goto done;
}

DBG ( "ICMP responding to ping\n" );

/* Change type to response and recalculate checksum */
icmp->type = ICMP_ECHO_RESPONSE;
icmp->chksum = 0;
icmp->chksum = tcpip_chksum ( icmp, len );

/* Transmit the response */
if ( ( rc = tcpip_tx ( iob_disown ( iobuf ), &icmp_protocol, st_dest,
st_src, NULL, NULL ) ) != 0 ) {
DBG ( "ICMP could not transmit ping response: %s\n",
strerror ( rc ) );
goto done;
}

done:
free_iob ( iobuf );
return rc;
}

/** ICMP TCP/IP protocol */
struct tcpip_protocol icmp_protocol __tcpip_protocol = {
.name = "ICMP",
.rx = icmp_rx,
.tcpip_proto = IP_ICMP,
};
3 changes: 3 additions & 0 deletions src/net/ipv4.c
Expand Up @@ -627,3 +627,6 @@ static int ipv4_create_routes ( void ) {
struct settings_applicator ipv4_settings_applicator __settings_applicator = {
.apply = ipv4_create_routes,
};

/* Drag in ICMP */
REQUIRE_OBJECT ( icmp );

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