/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 1991-2003 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 *
 * icmp4.c, Code implementing the Internet Control Message Protocol (v4) ICMP.
 */

#pragma ident   "%Z%%M% %I%     %E% SMI"

#include <sys/types.h>
#include <socket_impl.h>
#include <socket_inet.h>
#include <sys/salib.h>
#include <sys/socket.h>
#include <netinet/in_systm.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <netinet/udp.h>
#include <netinet/ip_icmp.h>
#include <sys/bootconf.h>
#include <sys/fcntl.h>

#include "icmp4.h"
#include "ipv4.h"
#include "ipv4_impl.h"
#include "mac.h"
#include "v4_sum_impl.h"
#include <sys/bootdebug.h>

/*
 * Handle ICMP redirects, ICMP echo messages. We only deal with redirects to a
 * different default router by changing the default route to the specified
 * value.
 */
void
icmp4(struct inetgram *igp, struct ip *iphp, uint16_t iphlen,
struct in_addr ipsrc)
{
        int             icmp_len;
        struct in_addr  our_ip;
        struct icmp     *icmphp;

        icmp_len = ntohs(iphp->ip_len) - iphlen;
        if (icmp_len < ICMP_MINLEN) {
#ifdef  DEBUG
                printf("icmp4: ICMP message from %s is too short\n",
                    inet_ntoa(ipsrc));
#endif  /* DEBUG */
                return;
        }

        icmphp = (struct icmp *)(igp->igm_mp->b_rptr + iphlen);

        /* check alignment */
        if ((uintptr_t)icmphp % sizeof (uint16_t)) {
                dprintf("icmp4: ICMP header not aligned (from %s)\n",
                    inet_ntoa(ipsrc));
                return;
        }
        if (ipv4cksum((uint16_t *)icmphp, icmp_len) != 0) {
                dprintf("icmp4: Bad ICMP checksum (from %s)\n",
                    inet_ntoa(ipsrc));
                return;
        }
        switch (icmphp->icmp_type) {
        case ICMP_REDIRECT:
                if (icmphp->icmp_code != ICMP_REDIRECT_HOST)
                        break;
                dprintf("ICMP Redirect to gateway %s.\n",
                    inet_ntoa(icmphp->icmp_gwaddr));
                if (ipv4_route(IPV4_ADD_ROUTE, RT_HOST, &icmphp->icmp_ip.ip_dst,
                    &icmphp->icmp_gwaddr) != 0) {
                        dprintf("icmp4: Cannot add route %s, %d\n",
                            inet_ntoa(icmphp->icmp_ip.ip_dst), errno);
                }
                break;
        case ICMP_UNREACH:
                /*
                 * Need to highlight an error on the socket, and save the
                 * destination address so that we can ensure it is destined
                 * to this socket. We need the port number to be sure...
                 */
                dprintf("ICMP destination unreachable (%s)\n",
                    inet_ntoa(icmphp->icmp_ip.ip_dst));
                break;
        case ICMP_ECHO:
                /*
                 * swap the source and destination IP addresses
                 * and send a reply right out.
                 */
                ipv4_getipaddr(&our_ip);
                if (our_ip.s_addr != INADDR_ANY) {
                        int                     s;
                        struct sockaddr_in      dest;

                        if ((s = socket(AF_INET, SOCK_RAW, IPPROTO_ICMP)) < 0) {
                                dprintf("icmp4: socket: %d\n", errno);
                                break;
                        }
                        icmphp->icmp_type = ICMP_ECHOREPLY;
                        icmphp->icmp_cksum = 0;
                        icmphp->icmp_cksum = ipv4cksum((uint16_t *)icmphp,
                            icmp_len);
                        dest.sin_family = AF_INET;
                        dest.sin_addr.s_addr = ipsrc.s_addr;
                        dest.sin_port = htons(0);
                        (void) sendto(s, (caddr_t)icmphp, icmp_len, 0,
                            (const struct sockaddr *)&dest, sizeof (dest));
                        (void) socket_close(s);
                }
                break;
        default:
                dprintf("icmp4: Unsupported ICMP message type: 0x%x "
                    "received from %s\n", icmphp->icmp_type, inet_ntoa(ipsrc));
                break;
        }
}