sys/lib/libsa/ip.c

   1 /* $NetBSD: ip.c,v 1.2 2011/05/13 23:35:09 nakayama Exp $ */
   2
   3 /*
   4  * Copyright (c) 1992 Regents of the University of California.
   5  * Copyright (c) 2010 Zoltan Arnold NAGY
   6  * All rights reserved.
   7  *
   8  * This software was developed by the Computer Systems Engineering group
   9  * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
  10  * contributed to Berkeley.
  11  *
  12  * Redistribution and use in source and binary forms, with or without
  13  * modification, are permitted provided that the following conditions
  14  * are met:
  15  * 1. Redistributions of source code must retain the above copyright
  16  *    notice, this list of conditions and the following disclaimer.
  17  * 2. Redistributions in binary form must reproduce the above copyright
  18  *    notice, this list of conditions and the following disclaimer in the
  19  *    documentation and/or other materials provided with the distribution.
  20  * 3. All advertising materials mentioning features or use of this software
  21  *    must display the following acknowledgement:
  22  *      This product includes software developed by the University of
  23  *      California, Lawrence Berkeley Laboratory and its contributors.
  24  * 4. Neither the name of the University nor the names of its contributors
  25  *    may be used to endorse or promote products derived from this software
  26  *    without specific prior written permission.
  27  *
  28  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  29  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  30  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  31  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  32  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  33  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  34  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  35  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  36  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  37  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  38  * SUCH DAMAGE.
  39  *
  40  */
  41
  42 #include <sys/param.h>
  43 #include <sys/socket.h>
  44 #include <net/if.h>
  45 #include <net/if_ether.h>
  46 #include <netinet/in.h>
  47 #include <netinet/in_systm.h>
  48 #include <netinet/ip.h>
  49 #include <netinet/ip_var.h>
  50 #include <netinet/udp.h>
  51 #include <netinet/udp_var.h>
  52
  53 #ifdef _STANDALONE
  54 #include <lib/libkern/libkern.h>
  55 #else
  56 #include <string.h>
  57 #endif
  58
  59 #include "stand.h"
  60 #include "net.h"
  61
  62 /*
  63  * sends an IP packet, if it's alredy constructed
  64 */
  65 static ssize_t
  66 _sendip(struct iodesc * d, struct ip * ip, size_t len)
  67 {
  68         u_char *ea;
  69
  70         if (ip->ip_dst.s_addr == INADDR_BROADCAST || ip->ip_src.s_addr == 0 ||
  71             netmask == 0 || SAMENET(ip->ip_src, ip->ip_dst, netmask)) {
  72                 ea = arpwhohas(d, ip->ip_dst);
  73         } else {
  74                 ea = arpwhohas(d, gateip);
  75         }
  76
  77         return sendether(d, ip, len, ea, ETHERTYPE_IP);
  78 }
  79
  80 /*
  81  * fills out the IP header
  82  * Caller must leave room for ethernet, ip and udp headers in front!
  83 */
  84 ssize_t
  85 sendip(struct iodesc * d, void *pkt, size_t len, u_int8_t proto)
  86 {
  87         ssize_t cc;
  88         struct ip *ip;
  89
  90         ip = (struct ip *) pkt - 1;
  91         len += sizeof(*ip);
  92
  93         (void) memset(ip, 0, sizeof(*ip));
  94
  95         ip->ip_v = IPVERSION;
  96         ip->ip_hl = sizeof(*ip) >> 2;
  97         ip->ip_len = htons(len);
  98         ip->ip_p = proto;
  99         ip->ip_ttl = IPDEFTTL;
 100         ip->ip_src = d->myip;
 101         ip->ip_dst = d->destip;
 102         ip->ip_sum = ip_cksum(ip, sizeof(*ip));
 103
 104         cc = _sendip(d, ip, len);
 105
 106         if (cc == -1)
 107                 return -1;
 108         if ((size_t) cc != len)
 109                 panic("sendip: bad write (%zd != %zu)", cc, len);
 110         return (cc - (sizeof(*ip)));
 111 }
 112
 113 /*
 114  * reads an IP packet
 115  * WARNING: the old version stripped the IP options, if there were
 116  * any. Because we have absolutely no idea if the upper layer needs
 117  * these or not, it's best to leave them there.
 118  *
 119  * The size returned is the size indicated in the header.
 120  */
 121 ssize_t
 122 readip(struct iodesc * d, void *pkt, size_t len, time_t tleft, u_int8_t proto)
 123 {
 124         ssize_t n;
 125         size_t hlen;
 126         struct ip *ip;
 127         u_int16_t etype;
 128
 129         ip = (struct ip *) pkt - 1;
 130
 131         n = readether(d, ip, len + sizeof(*ip), tleft, &etype);
 132         if (n == -1 || (size_t) n < sizeof(*ip))
 133                 return -1;
 134
 135         if (etype == ETHERTYPE_ARP) {
 136                 struct arphdr *ah = (void *) ip;
 137                 if (ah->ar_op == htons(ARPOP_REQUEST)) {
 138                         /* Send ARP reply */
 139                         arp_reply(d, ah);
 140                 }
 141                 return -1;
 142         }
 143
 144         if (etype != ETHERTYPE_IP) {
 145 #ifdef NET_DEBUG
 146                 if (debug)
 147                         printf("readip: not IP. ether_type=%x\n", etype);
 148 #endif
 149                 return -1;
 150         }
 151
 152         /* Check ip header */
 153         if (ip->ip_v != IPVERSION ||
 154             ip->ip_p != proto) { /* half char */
 155 #ifdef NET_DEBUG
 156                 if (debug) {
 157                         printf("readip: wrong IP version or wrong proto "
 158                                 "ip_v=%d ip_p=%d\n", ip->ip_v, ip->ip_p);
 159                 }
 160 #endif
 161                 return -1;
 162         }
 163
 164         hlen = ip->ip_hl << 2;
 165         if (hlen < sizeof(*ip) || ip_cksum(ip, hlen) != 0) {
 166 #ifdef NET_DEBUG
 167                 if (debug)
 168                         printf("readip: short hdr or bad cksum.\n");
 169 #endif
 170                 return -1;
 171         }
 172         if (n < ntohs(ip->ip_len)) {
 173 #ifdef NET_DEBUG
 174                 if (debug)
 175                         printf("readip: bad length %d < %d.\n",
 176                                (int) n, ntohs(ip->ip_len));
 177 #endif
 178                 return -1;
 179         }
 180         if (d->myip.s_addr && ip->ip_dst.s_addr != d->myip.s_addr) {
 181 #ifdef NET_DEBUG
 182                 if (debug) {
 183                         printf("readip: bad saddr %s != ", inet_ntoa(d->myip));
 184                         printf("%s\n", inet_ntoa(ip->ip_dst));
 185                 }
 186 #endif
 187                 return -1;
 188         }
 189         return (ntohs(ip->ip_len) - 20);
 190 }