1/*
2 * Copyright (C) 2009 Michael Brown <mbrown@fensystems.co.uk>.
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License as
6 * published by the Free Software Foundation; either version 2 of the
7 * License, or any later version.
8 *
9 * This program is distributed in the hope that it will be useful, but
10 * WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
12 * General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
17 */
18
19FILE_LICENCE ( GPL2_OR_LATER );
20
21#include <string.h>
22#include <errno.h>
23#include <gpxe/iobuf.h>
24#include <gpxe/in.h>
25#include <gpxe/tcpip.h>
26#include <gpxe/icmp.h>
27
28/** @file
29 *
30 * ICMP protocol
31 *
32 */
33
34struct tcpip_protocol icmp_protocol __tcpip_protocol;
35
36/**
37 * Process a received packet
38 *
39 * @v iobuf		I/O buffer
40 * @v st_src		Partially-filled source address
41 * @v st_dest		Partially-filled destination address
42 * @v pshdr_csum	Pseudo-header checksum
43 * @ret rc		Return status code
44 */
45static int icmp_rx ( struct io_buffer *iobuf, struct sockaddr_tcpip *st_src,
46		     struct sockaddr_tcpip *st_dest,
47		     uint16_t pshdr_csum __unused ) {
48	struct icmp_header *icmp = iobuf->data;
49	size_t len = iob_len ( iobuf );
50	unsigned int csum;
51	int rc;
52
53	/* Sanity check */
54	if ( len < sizeof ( *icmp ) ) {
55		DBG ( "ICMP packet too short at %zd bytes (min %zd bytes)\n",
56		      len, sizeof ( *icmp ) );
57		rc = -EINVAL;
58		goto done;
59	}
60
61	/* Verify checksum */
62	csum = tcpip_chksum ( icmp, len );
63	if ( csum != 0 ) {
64		DBG ( "ICMP checksum incorrect (is %04x, should be 0000)\n",
65		      csum );
66		DBG_HD ( icmp, len );
67		rc = -EINVAL;
68		goto done;
69	}
70
71	/* We respond only to pings */
72	if ( icmp->type != ICMP_ECHO_REQUEST ) {
73		DBG ( "ICMP ignoring type %d\n", icmp->type );
74		rc = 0;
75		goto done;
76	}
77
78	DBG ( "ICMP responding to ping\n" );
79
80	/* Change type to response and recalculate checksum */
81	icmp->type = ICMP_ECHO_RESPONSE;
82	icmp->chksum = 0;
83	icmp->chksum = tcpip_chksum ( icmp, len );
84
85	/* Transmit the response */
86	if ( ( rc = tcpip_tx ( iob_disown ( iobuf ), &icmp_protocol, st_dest,
87			       st_src, NULL, NULL ) ) != 0 ) {
88		DBG ( "ICMP could not transmit ping response: %s\n",
89		      strerror ( rc ) );
90		goto done;
91	}
92
93 done:
94	free_iob ( iobuf );
95	return rc;
96}
97
98/** ICMP TCP/IP protocol */
99struct tcpip_protocol icmp_protocol __tcpip_protocol = {
100	.name = "ICMP",
101	.rx = icmp_rx,
102	.tcpip_proto = IP_ICMP,
103};
104