lib/libstand/udp.c

   1 /* Taken from $NetBSD: net.c,v 1.20 1997/12/26 22:41:30 scottr Exp $    */
   2
   3 /*
   4  * Copyright (c) 1992 Regents of the University of California.
   5  * All rights reserved.
   6  *
   7  * This software was developed by the Computer Systems Engineering group
   8  * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
   9  * contributed to Berkeley.
  10  *
  11  * Redistribution and use in source and binary forms, with or without
  12  * modification, are permitted provided that the following conditions
  13  * are met:
  14  * 1. Redistributions of source code must retain the above copyright
  15  *    notice, this list of conditions and the following disclaimer.
  16  * 2. Redistributions in binary form must reproduce the above copyright
  17  *    notice, this list of conditions and the following disclaimer in the
  18  *    documentation and/or other materials provided with the distribution.
  19  * 3. All advertising materials mentioning features or use of this software
  20  *    must display the following acknowledgement:
  21  *      This product includes software developed by the University of
  22  *      California, Lawrence Berkeley Laboratory and its contributors.
  23  * 4. Neither the name of the University nor the names of its contributors
  24  *    may be used to endorse or promote products derived from this software
  25  *    without specific prior written permission.
  26  *
  27  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  28  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  29  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  30  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  31  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  32  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  33  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  34  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  35  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  36  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  37  * SUCH DAMAGE.
  38  *
  39  * @(#) Header: net.c,v 1.9 93/08/06 19:32:15 leres Exp  (LBL)
  40  * $FreeBSD: src/lib/libstand/udp.c,v 1.1.2.1 2000/04/15 03:09:29 ps Exp $
  41  * $DragonFly: src/lib/libstand/udp.c,v 1.4 2005/12/11 02:27:26 swildner Exp $
  42  */
  43
  44 #include <sys/param.h>
  45 #include <sys/socket.h>
  46
  47 #include <string.h>
  48
  49 #include <net/if.h>
  50 #include <netinet/in.h>
  51 #include <netinet/if_ether.h>
  52 #include <netinet/in_systm.h>
  53
  54 #include <netinet/ip.h>
  55 #include <netinet/ip_var.h>
  56 #include <netinet/udp.h>
  57 #include <netinet/udp_var.h>
  58
  59 #include "stand.h"
  60 #include "net.h"
  61
  62 /* Caller must leave room for ethernet, ip and udp headers in front!! */
  63 ssize_t
  64 sendudp(struct iodesc *d, void *pkt, size_t len)
  65 {
  66         ssize_t cc;
  67         struct ip *ip;
  68         struct udphdr *uh;
  69         u_char *ea;
  70
  71 #ifdef NET_DEBUG
  72         if (debug) {
  73                 printf("sendudp: d=%lx called.\n", (long)d);
  74                 if (d) {
  75                         printf("saddr: %s:%d",
  76                             inet_ntoa(d->myip), ntohs(d->myport));
  77                         printf(" daddr: %s:%d\n",
  78                             inet_ntoa(d->destip), ntohs(d->destport));
  79                 }
  80         }
  81 #endif
  82
  83         uh = (struct udphdr *)pkt - 1;
  84         ip = (struct ip *)uh - 1;
  85         len += sizeof(*ip) + sizeof(*uh);
  86
  87         bzero(ip, sizeof(*ip) + sizeof(*uh));
  88
  89         ip->ip_v = IPVERSION;                   /* half-char */
  90         ip->ip_hl = sizeof(*ip) >> 2;           /* half-char */
  91         ip->ip_len = htons(len);
  92         ip->ip_p = IPPROTO_UDP;                 /* char */
  93         ip->ip_ttl = IP_TTL;                    /* char */
  94         ip->ip_src = d->myip;
  95         ip->ip_dst = d->destip;
  96         ip->ip_sum = in_cksum(ip, sizeof(*ip));  /* short, but special */
  97
  98         uh->uh_sport = d->myport;
  99         uh->uh_dport = d->destport;
 100         uh->uh_ulen = htons(len - sizeof(*ip));
 101
 102 #ifndef UDP_NO_CKSUM
 103         {
 104                 struct udpiphdr *ui;
 105                 struct ip tip;
 106
 107                 /* Calculate checksum (must save and restore ip header) */
 108                 tip = *ip;
 109                 ui = (struct udpiphdr *)ip;
 110                 bzero(&ui->ui_x1, sizeof(ui->ui_x1));
 111                 ui->ui_len = uh->uh_ulen;
 112                 uh->uh_sum = in_cksum(ui, len);
 113                 *ip = tip;
 114         }
 115 #endif
 116
 117         if (ip->ip_dst.s_addr == INADDR_BROADCAST || ip->ip_src.s_addr == 0 ||
 118             netmask == 0 || SAMENET(ip->ip_src, ip->ip_dst, netmask))
 119                 ea = arpwhohas(d, ip->ip_dst);
 120         else
 121                 ea = arpwhohas(d, gateip);
 122
 123         cc = sendether(d, ip, len, ea, ETHERTYPE_IP);
 124         if (cc == -1)
 125                 return (-1);
 126         if (cc != len)
 127                 panic("sendudp: bad write (%d != %d)", cc, len);
 128         return (cc - (sizeof(*ip) + sizeof(*uh)));
 129 }
 130
 131 /*
 132  * Receive a UDP packet and validate it is for us.
 133  * Caller leaves room for the headers (Ether, IP, UDP)
 134  */
 135 ssize_t
 136 readudp(struct iodesc *d, void *pkt, size_t len, time_t tleft)
 137 {
 138         ssize_t n;
 139         size_t hlen;
 140         struct ip *ip;
 141         struct udphdr *uh;
 142         u_int16_t etype;        /* host order */
 143
 144 #ifdef NET_DEBUG
 145         if (debug)
 146                 printf("readudp: called\n");
 147 #endif
 148
 149         uh = (struct udphdr *)pkt - 1;
 150         ip = (struct ip *)uh - 1;
 151
 152         n = readether(d, ip, len + sizeof(*ip) + sizeof(*uh), tleft, &etype);
 153         if (n == -1 || n < sizeof(*ip) + sizeof(*uh))
 154                 return -1;
 155
 156         /* Ethernet address checks now in readether() */
 157
 158         /* Need to respond to ARP requests. */
 159         if (etype == ETHERTYPE_ARP) {
 160                 struct arphdr *ah = (void *)ip;
 161                 if (ah->ar_op == htons(ARPOP_REQUEST)) {
 162                         /* Send ARP reply */
 163                         arp_reply(d, ah);
 164                 }
 165                 return -1;
 166         }
 167
 168         if (etype != ETHERTYPE_IP) {
 169 #ifdef NET_DEBUG
 170                 if (debug)
 171                         printf("readudp: not IP. ether_type=%x\n", etype);
 172 #endif
 173                 return -1;
 174         }
 175
 176         /* Check ip header */
 177         if (ip->ip_v != IPVERSION ||
 178             ip->ip_p != IPPROTO_UDP) {  /* half char */
 179 #ifdef NET_DEBUG
 180                 if (debug)
 181                         printf("readudp: IP version or not UDP. ip_v=%d ip_p=%d\n", ip->ip_v, ip->ip_p);
 182 #endif
 183                 return -1;
 184         }
 185
 186         hlen = ip->ip_hl << 2;
 187         if (hlen < sizeof(*ip) ||
 188             in_cksum(ip, hlen) != 0) {
 189 #ifdef NET_DEBUG
 190                 if (debug)
 191                         printf("readudp: short hdr or bad cksum.\n");
 192 #endif
 193                 return -1;
 194         }
 195         if (n < ntohs(ip->ip_len)) {
 196 #ifdef NET_DEBUG
 197                 if (debug)
 198                         printf("readudp: bad length %d < %d.\n",
 199                                (int)n, ntohs(ip->ip_len));
 200 #endif
 201                 return -1;
 202         }
 203         if (d->myip.s_addr && ip->ip_dst.s_addr != d->myip.s_addr) {
 204 #ifdef NET_DEBUG
 205                 if (debug) {
 206                         printf("readudp: bad saddr %s != ", inet_ntoa(d->myip));
 207                         printf("%s\n", inet_ntoa(ip->ip_dst));
 208                 }
 209 #endif
 210                 return -1;
 211         }
 212
 213         /* If there were ip options, make them go away */
 214         if (hlen != sizeof(*ip)) {
 215                 bcopy(((u_char *)ip) + hlen, uh, len - hlen);
 216                 ip->ip_len = htons(sizeof(*ip));
 217                 n -= hlen - sizeof(*ip);
 218         }
 219         if (uh->uh_dport != d->myport) {
 220 #ifdef NET_DEBUG
 221                 if (debug)
 222                         printf("readudp: bad dport %d != %d\n",
 223                                 d->myport, ntohs(uh->uh_dport));
 224 #endif
 225                 return -1;
 226         }
 227
 228 #ifndef UDP_NO_CKSUM
 229         if (uh->uh_sum) {
 230                 struct udpiphdr *ui;
 231                 struct ip tip;
 232
 233                 n = ntohs(uh->uh_ulen) + sizeof(*ip);
 234                 if (n > RECV_SIZE - ETHER_SIZE) {
 235                         printf("readudp: huge packet, udp len %d\n", (int)n);
 236                         return -1;
 237                 }
 238
 239                 /* Check checksum (must save and restore ip header) */
 240                 tip = *ip;
 241                 ui = (struct udpiphdr *)ip;
 242                 bzero(&ui->ui_x1, sizeof(ui->ui_x1));
 243                 ui->ui_len = uh->uh_ulen;
 244                 if (in_cksum(ui, n) != 0) {
 245 #ifdef NET_DEBUG
 246                         if (debug)
 247                                 printf("readudp: bad cksum\n");
 248 #endif
 249                         *ip = tip;
 250                         return -1;
 251                 }
 252                 *ip = tip;
 253         }
 254 #endif
 255         if (ntohs(uh->uh_ulen) < sizeof(*uh)) {
 256 #ifdef NET_DEBUG
 257                 if (debug)
 258                         printf("readudp: bad udp len %d < %d\n",
 259                                 ntohs(uh->uh_ulen), (int)sizeof(*uh));
 260 #endif
 261                 return -1;
 262         }
 263
 264         n -= sizeof(*ip) + sizeof(*uh);
 265         return (n);
 266 }