/* $NetBSD: ip.c,v 1.5 2022/07/08 07:02:47 skrll Exp $ */

/*
* Copyright (c) 1992 Regents of the University of California.
* Copyright (c) 2010 Zoltan Arnold NAGY
* All rights reserved.
*
* This software was developed by the Computer Systems Engineering group
* at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
* contributed to Berkeley.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
*    notice, this list of conditions and the following disclaimer in the
*    documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
*    must display the following acknowledgement:
*      This product includes software developed by the University of
*      California, Lawrence Berkeley Laboratory and its contributors.
* 4. Neither the name of the University nor the names of its contributors
*    may be used to endorse or promote products derived from this software
*    without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/

#include <sys/param.h>
#include <sys/socket.h>
#include <net/if.h>
#include <net/if_ether.h>
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <netinet/ip_var.h>
#include <netinet/udp.h>
#include <netinet/udp_var.h>

#ifdef _STANDALONE
#include <lib/libkern/libkern.h>
#else
#include <string.h>
#endif

#include "stand.h"
#include "net.h"

/*
* sends an IP packet, if it's already constructed
*/
static ssize_t
_sendip(struct iodesc *d, struct ip *ip, size_t len)
{
       u_char *ea;

       if (ip->ip_dst.s_addr == INADDR_BROADCAST || ip->ip_src.s_addr == 0 ||
           netmask == 0 || SAMENET(ip->ip_src, ip->ip_dst, netmask)) {
               ea = arpwhohas(d, ip->ip_dst);
       } else {
               ea = arpwhohas(d, gateip);
       }

       return sendether(d, ip, len, ea, ETHERTYPE_IP);
}

/*
* fills out the IP header
* Caller must leave room for ethernet, ip and udp headers in front!
*/
ssize_t
sendip(struct iodesc *d, void *pkt, size_t len, u_int8_t proto)
{
       ssize_t cc;
       struct ip *ip;

       ip = (struct ip *)pkt - 1;
       len += sizeof(*ip);

       memset(ip, 0, sizeof(*ip));

       ip->ip_v = IPVERSION;
       ip->ip_hl = sizeof(*ip) >> 2;
       ip->ip_len = htons(len);
       ip->ip_p = proto;
       ip->ip_ttl = IPDEFTTL;
       ip->ip_src = d->myip;
       ip->ip_dst = d->destip;
       ip->ip_sum = ip_cksum(ip, sizeof(*ip));

       cc = _sendip(d, ip, len);

       if (cc == -1)
               return -1;
       if ((size_t)cc != len)
               panic("%s: bad write (%zd != %zu)", __func__, cc, len);
       return (cc - (sizeof(*ip)));
}

/*
* reads an IP packet
* WARNING: the old version stripped the IP options, if there were
* any. Because we have absolutely no idea if the upper layer needs
* these or not, it's best to leave them there.
*
* The size returned is the size indicated in the header.
*/
ssize_t
readip(struct iodesc *d, void *pkt, size_t len, time_t tleft, u_int8_t proto)
{
       ssize_t n;
       size_t hlen;
       struct ip *ip;
       u_int16_t etype;

       ip = (struct ip *)pkt - 1;

       n = readether(d, ip, len + sizeof(*ip), tleft, &etype);
       if (n == -1 || (size_t)n < sizeof(*ip))
               return -1;

       if (etype == ETHERTYPE_ARP) {
               struct arphdr *ah = (void *)ip;
               if (n < (ssize_t)(sizeof(*ah) + 2 * (ah->ar_hln + ah->ar_pln))) {
                       return -1;
               }
               if (ah->ar_op == htons(ARPOP_REQUEST)) {
                       /* Send ARP reply */
                       arp_reply(d, ah);
               }
               return -1;
       }
       if (etype != ETHERTYPE_IP) {
               return -1;
       }

       if (ip->ip_v != IPVERSION || ip->ip_p != proto) {
               return -1;
       }

       hlen = ip->ip_hl << 2;
       if (hlen != sizeof(*ip) || ip_cksum(ip, hlen) != 0) {
               return -1;
       }
       if (ntohs(ip->ip_len) < hlen) {
               return -1;
       }
       if (n < ntohs(ip->ip_len)) {
               return -1;
       }
       if (d->myip.s_addr && ip->ip_dst.s_addr != d->myip.s_addr) {
               return -1;
       }

       return (ntohs(ip->ip_len) - hlen);
}